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http://paperity.org/p/79010827/inequalities-of-extended-beta-and-extended-hypergeometric-functions | # Inequalities of extended beta and extended hypergeometric functions
Journal of Inequalities and Applications, Jan 2017
We study the log-convexity of the extended beta functions. As a consequence, we establish Turán-type inequalities. The monotonicity, log-convexity, log-concavity of extended hypergeometric functions are deduced by using the inequalities on extended beta functions. The particular cases of those results also give the Turán-type inequalities for extended confluent and extended Gaussian hypergeometric functions. Some reverses of Turán-type inequalities are also derived. MSC: 33B15, 33B99.
This is a preview of a remote PDF: http://www.journalofinequalitiesandapplications.com/content/pdf/s13660-016-1276-9.pdf
Saiful Mondal. Inequalities of extended beta and extended hypergeometric functions, Journal of Inequalities and Applications, 2017, 10, DOI: 10.1186/s13660-016-1276-9 | {"extraction_info": {"found_math": false, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.9843825101852417, "perplexity": 1819.7368590478266}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2018-09/segments/1518891814079.59/warc/CC-MAIN-20180222081525-20180222101525-00376.warc.gz"} |
https://worldwidescience.org/topicpages/h/high-efficiency+multi-collector+thermal.html | #### Sample records for high-efficiency multi-collector thermal
1. Measurement of the delta34S value in methionine by double spike multi-collector thermal ionization mass spectrometry using Carius tube digestion.
Science.gov (United States)
Mann, Jacqueline L; Kelly, W Robert
2010-09-15
Methionine is an essential amino acid and is the primary source of sulfur for humans. Using the double spike ((33)S-(36)S) multi-collector thermal ionization mass spectrometry (MC-TIMS) technique, three sample bottles of a methionine material obtained from the Institute for Reference Materials and Measurements have been measured for delta(34)S and sulfur concentration. The mean delta(34)S value, relative to Vienna Canyon Diablo Troilite (VCDT), determined was 10.34 +/- 0.11 per thousand (n = 9) with the uncertainty reported as expanded uncertainties (U). These delta(34)S measurements include a correction for blank which has been previously ignored in studies of sulfur isotopic composition. The sulfur concentrations for the three bottles range from 56 to 88 microg/g. The isotope composition and concentration results demonstrate the high accuracy and precision of the DS-MC-TIMS technique for measuring sulfur in methionine.
2. High efficiency thermal energy storage system for utility applications
International Nuclear Information System (INIS)
1979-01-01
A concept of coupling a high efficiency base loaded coal or nuclear power plant with a thermal energy storage scheme for efficient and low-cost intermediate and peaking power is presented. A portion of the power plant's thermal output is used directly to generate superheated steam for continuous operation of a conventional turbine-generator to product base-load power. The remaining thermal output is used on a continuous basis to heat a conventional heat transfer salt (such as the eutectic composition of KaNO 3 /NaNO 3 /NaNO 2 ), which is stored in a high-temperature reservoir [538 0 C (1000 0 F)]. During peak demand periods, the salt is circulated from the high-temperature reservoir to a low-temperature reservoir through steam generators in order to provide peaking power from a conventional steam cycle plant. The period of operation can vary, but may typically be the equivalent of about 4 to 8 full-power hours each day. The system can be tailored to meet the utilities' load demand by varying the base-load level and the period of operation of the peak-load system
3. High Efficiency and Low Cost Thermal Energy Storage System
Energy Technology Data Exchange (ETDEWEB)
Sienicki, James J. [Argonne National Lab. (ANL), Argonne, IL (United States). Nuclear Engineering Division; Lv, Qiuping [Argonne National Lab. (ANL), Argonne, IL (United States). Nuclear Engineering Division; Moisseytsev, Anton [Argonne National Lab. (ANL), Argonne, IL (United States). Nuclear Engineering Division; Bucknor, Matthew [Argonne National Lab. (ANL), Argonne, IL (United States). Nuclear Engineering Division
2017-09-29
BgtL, LLC (BgtL) is focused on developing and commercializing its proprietary compact technology for processes in the energy sector. One such application is a compact high efficiency Thermal Energy Storage (TES) system that utilizes the heat of fusion through phase change between solid and liquid to store and release energy at high temperatures and incorporate state-of-the-art insulation to minimize heat dissipation. BgtL’s TES system would greatly improve the economics of existing nuclear and coal-fired power plants by allowing the power plant to store energy when power prices are low and sell power into the grid when prices are high. Compared to existing battery storage technology, BgtL’s novel thermal energy storage solution can be significantly less costly to acquire and maintain, does not have any waste or environmental emissions, and does not deteriorate over time; it can keep constant efficiency and operates cleanly and safely. BgtL’s engineers are experienced in this field and are able to design and engineer such a system to a specific power plant’s requirements. BgtL also has a strong manufacturing partner to fabricate the system such that it qualifies for an ASME code stamp. BgtL’s vision is to be the leading provider of compact systems for various applications including energy storage. BgtL requests that all technical information about the TES designs be protected as proprietary information. To honor that request, only non-proprietay summaries are included in this report.
4. High-efficiency thermal switch based on topological Josephson junctions
Science.gov (United States)
Sothmann, Björn; Giazotto, Francesco; Hankiewicz, Ewelina M.
2017-02-01
We propose theoretically a thermal switch operating by the magnetic-flux controlled diffraction of phase-coherent heat currents in a thermally biased Josephson junction based on a two-dimensional topological insulator. For short junctions, the system shows a sharp switching behavior while for long junctions the switching is smooth. Physically, the switching arises from the Doppler shift of the superconducting condensate due to screening currents induced by a magnetic flux. We suggest a possible experimental realization that exhibits a relative temperature change of 40% between the on and off state for realistic parameters. This is a factor of two larger than in recently realized thermal modulators based on conventional superconducting tunnel junctions.
5. Development of the ultra high efficiency thermal power generation facility
Energy Technology Data Exchange (ETDEWEB)
Sano, Toshihiro
2010-09-15
In order to prevent global warming, attention is focused on nuclear power generation and renewable energy such as wind and solar power generation. The electric power suppliers of Japan are aiming to increase the amount of nuclear and non-fossil fuel power generation over 50% of the total power generation by 2020. But this means that the remaining half will still be of thermal power generation using fossil fuel and will still play an important role. Under such circumstances, further efficiency improvement of the thermal power generation and its aggressive implementation is ongoing in Japan.
6. High-efficiency thermal ionization sources for mass spectrometry
International Nuclear Information System (INIS)
Olivares, Jose A.
1996-01-01
A version of the thermal ionization cavity (TIC) source developed specifically for use in mass spectrometry is presented. The performance of this ion source has been characterized extensively both with the use of an isotope separator and a quadrupole mass spectrometer. A detailed description of the TIC source for mass spectrometry is given along with the performance characteristics observed
7. A high efficiency thermal ionization source adapted to mass spectrometers
International Nuclear Information System (INIS)
Chamberlin, E.P.; Olivares, J.A.
1996-01-01
A tungsten crucible thermal ionization source mounted on a quadrupole mass spectrometer is described. The crucible is a disposable rod with a fine hole bored in one end; it is heated by electron bombardment. The schematic design of the assembly, including water cooling, is described and depicted. Historically, the design is derived from that of ion sources used on ion separators at Los Alamos and Dubna, but the crucible is made smaller and simplified. 10 refs., 4 figs
8. Functionalized Graphene Enables Highly Efficient Solar Thermal Steam Generation.
Science.gov (United States)
Yang, Junlong; Pang, Yunsong; Huang, Weixin; Shaw, Scott K; Schiffbauer, Jarrod; Pillers, Michelle Anne; Mu, Xin; Luo, Shirui; Zhang, Teng; Huang, Yajiang; Li, Guangxian; Ptasinska, Sylwia; Lieberman, Marya; Luo, Tengfei
2017-06-27
The ability to efficiently utilize solar thermal energy to enable liquid-to-vapor phase transition has great technological implications for a wide variety of applications, such as water treatment and chemical fractionation. Here, we demonstrate that functionalizing graphene using hydrophilic groups can greatly enhance the solar thermal steam generation efficiency. Our results show that specially functionalized graphene can improve the overall solar-to-vapor efficiency from 38% to 48% at one sun conditions compared to chemically reduced graphene oxide. Our experiments show that such an improvement is a surface effect mainly attributed to the more hydrophilic feature of functionalized graphene, which influences the water meniscus profile at the vapor-liquid interface due to capillary effect. This will lead to thinner water films close to the three-phase contact line, where the water surface temperature is higher since the resistance of thinner water film is smaller, leading to more efficient evaporation. This strategy of functionalizing graphene to make it more hydrophilic can be potentially integrated with the existing macroscopic heat isolation strategies to further improve the overall solar-to-vapor conversion efficiency.
9. Thermally Activated Delayed Fluorescence in Polymers: A New Route toward Highly Efficient Solution Processable OLEDs.
Science.gov (United States)
Nikolaenko, Andrey E; Cass, Michael; Bourcet, Florence; Mohamad, David; Roberts, Matthew
2015-11-25
Efficient intermonomer thermally activated delayed fluorescence is demonstrated for the first time, opening a new route to achieving high-efficiency solution processable polymer light-emitting device materials. External quantum efficiency (EQE) of up to 10% is achieved in a simple fully solution-processed device structure, and routes for further EQE improvement identified. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
10. High-efficiency white organic light-emitting diodes using thermally activated delayed fluorescence
International Nuclear Information System (INIS)
Nishide, Jun-ichi; Hiraga, Yasuhide; Nakanotani, Hajime; Adachi, Chihaya
2014-01-01
White organic light-emitting diodes (WOLEDs) have attracted much attention recently, aimed for next-generation lighting sources because of their high potential to realize high electroluminescence efficiency, flexibility, and low-cost manufacture. Here, we demonstrate high-efficiency WOLED using red, green, and blue thermally activated delayed fluorescence materials as emissive dopants to generate white electroluminescence. The WOLED has a maximum external quantum efficiency of over 17% with Commission Internationale de l'Eclairage coordinates of (0.30, 0.38).
11. Vertically Aligned Graphene Sheets Membrane for Highly Efficient Solar Thermal Generation of Clean Water.
Science.gov (United States)
Zhang, Panpan; Li, Jing; Lv, Lingxiao; Zhao, Yang; Qu, Liangti
2017-05-23
Efficient utilization of solar energy for clean water is an attractive, renewable, and environment friendly way to solve the long-standing water crisis. For this task, we prepared the long-range vertically aligned graphene sheets membrane (VA-GSM) as the highly efficient solar thermal converter for generation of clean water. The VA-GSM was prepared by the antifreeze-assisted freezing technique we developed, which possessed the run-through channels facilitating the water transport, high light absorption capacity for excellent photothermal transduction, and the extraordinary stability in rigorous conditions. As a result, VA-GSM has achieved average water evaporation rates of 1.62 and 6.25 kg m -2 h -1 under 1 and 4 sun illumination with a superb solar thermal conversion efficiency of up to 86.5% and 94.2%, respectively, better than that of most carbon materials reported previously, which can efficiently produce the clean water from seawater, common wastewater, and even concentrated acid and/or alkali solutions.
12. Highly Efficient PCDTBT:PC71 BM Based Photovoltaic Devices without Thermal Annealing Treatment
International Nuclear Information System (INIS)
Yang Shao-Peng; Kong Wei-Guang; Liu Bo-Ya; Fu Guang-Sheng; Zheng Wen-Yao; Li Bao-Min; Liu Xian-Hao
2011-01-01
We propose an effective method to fabricate highly efficient organic photovoltaic cells based on poly [N-9 - heptadecanyl-2, 7-carbazole-alt-5,5-(4'7'-di-2-thienyl-2'1'3-b-enzothiadiazole): [6,6]-phenyl C 71 -butyric acid methyl ester (PCDTBT:PC 71 BM). A power conversion efficiency of as high as 5.6% and a fill factor of 53.7% are achieved from the optimized cells. The influence of surface morphology of the active layer on the performance of the cells is also investigated. (cross-disciplinary physics and related areas of science and technology)
13. High efficiency thermal to electric energy conversion using selective emitters and spectrally tuned solar cells
Science.gov (United States)
Chubb, Donald L.; Flood, Dennis J.; Lowe, Roland A.
1992-01-01
Thermophotovoltaic (TPV) systems are attractive possibilities for direct thermal-to-electric energy conversion, but have typically required the use of black body radiators operating at high temperatures. Recent advances in both the understanding and performance of solid rare-earth oxide selective emitters make possible the use of TPV at temperatures as low as 1500 K. Depending on the nature of parasitic losses, overall thermal-to-electric conversion efficiencies greater than 20 percent are feasible.
14. Selectively coated high efficiency glazing for solar-thermal flat-plate collectors
International Nuclear Information System (INIS)
Ehrmann, N.; Reineke-Koch, R.
2012-01-01
In order to increase the efficiency of solar-thermal flat-plate collectors at temperatures above 100 °C or with low solar irradiation, we implement a double glazing with a low-emitting (low-e) coating on the inner pane to improve the insulation of the transparent cover. Since commercially available low-e glazing provides only insufficient solar transmittance for the application in thermal flat-plate collectors we are developing a sputter-deposited low e-coating system based on transparent conductive oxides which provides a high solar transmittance of 85% due to additional antireflective coatings and the use of low-iron glass substrates. Durability tests of the developed coating system show that our low e-coating system is well suitable even at high temperatures, humidity and condensation.
15. High efficiency direct thermal to electric energy conversion from radioisotope decay using selective emitters and spectrally tuned solar cells
Science.gov (United States)
Chubb, Donald L.; Flood, Dennis J.; Lowe, Roland A.
1993-01-01
Thermophotovoltaic (TPV) systems are attractive possibilities for direct thermal-to-electric energy conversion, but have typically required the use of black body radiators operating at high temperatures. Recent advances in both the understanding and performance of solid rare-earth oxide selective emitters make possible the use of TPV at temperatures as low as 1200K. Both selective emitter and filter system TPV systems are feasible. However, requirements on the filter system are severe in order to attain high efficiency. A thin-film of a rare-earth oxide is one method for producing an efficient, rugged selective emitter. An efficiency of 0.14 and power density of 9.2 W/KG at 1200K is calculated for a hypothetical thin-film neodymia (Nd2O3) selective emitter TPV system that uses radioisotope decay as the thermal energy source.
16. High efficiency direct thermal to electric energy conversion from radioisotope decay using selective emitters and spectrally tuned solar cells
International Nuclear Information System (INIS)
Chubb, D.L.; Flood, D.J.; Lowe, R.A.
1993-08-01
Thermophotovoltaic (TPV) systems are attractive possibilities for direct thermal-to-electric energy conversion, but have typically required the use of black body radiators operating at high temperatures. Recent advances in both the understanding and performance of solid rare-earth oxide selective emitters make possible the use of TPV at temperatures as low as 1200K. Both selective emitter and filter system TPV systems are feasible. However, requirements on the filter system are severe in order to attain high efficiency. A thin-film of a rare-earth oxide is one method for producing an efficient, rugged selective emitter. An efficiency of 0.14 and power density of 9.2 W/KG at 1200K is calculated for a hypothetical thin-film neodymia (Nd2O3) selective emitter TPV system that uses radioisotope decay as the thermal energy source
17. Intrinsic Flame-Retardant and Thermally Stable Epoxy Endowed by a Highly Efficient, Multifunctional Curing Agent
Directory of Open Access Journals (Sweden)
Chunlei Dong
2016-12-01
Full Text Available It is difficult to realize flame retardancy of epoxy without suffering much detriment in thermal stability. To solve the problem, a super-efficient phosphorus-nitrogen-containing reactive-type flame retardant, 10-(hydroxy(4-hydroxyphenylmethyl-5,10-dihydrophenophosphazinine-10-oxide (HB-DPPA is synthesized and characterized. When it is used as a co-curing agent of 4,4′-methylenedianiline (DDM for curing diglycidyl ether of bisphenol A (DGEBA, the cured epoxy achieves UL-94 V-0 rating with the limiting oxygen index of 29.3%. In this case, the phosphorus content in the system is exceptionally low (0.18 wt %. To the best of our knowledge, it currently has the highest efficiency among similar epoxy systems. Such excellent flame retardancy originates from the exclusive chemical structure of the phenophosphazine moiety, in which the phosphorus element is stabilized by the two adjacent aromatic rings. The action in the condensed phase is enhanced and followed by pressurization of the pyrolytic gases that induces the blowing-out effect during combustion. The cone calorimeter result reveals the formation of a unique intumescent char structure with five discernible layers. Owing to the super-efficient flame retardancy and the rigid molecular structure of HB-DPPA, the flame-retardant epoxy acquires high thermal stability and its initial decomposition temperature only decreases by 4.6 °C as compared with the unmodified one.
18. Highly efficient electroluminescence from a solution-processable thermally activated delayed fluorescence emitter
Energy Technology Data Exchange (ETDEWEB)
Wada, Yoshimasa; Kubo, Shosei; Suzuki, Katsuaki; Kaji, Hironori, E-mail: kaji@scl.kyoto-u.ac.jp [Institute for Chemical Research, Kyoto University, Uji, Kyoto 611-0011 (Japan); Shizu, Katsuyuki [Institute for Chemical Research, Kyoto University, Uji, Kyoto 611-0011 (Japan); Center for Organic Photonics and Electronics Research (OPERA), Kyushu University, 744 Motooka, Nishi, Fukuoka 819-0395 (Japan); Tanaka, Hiroyuki [Center for Organic Photonics and Electronics Research (OPERA), Kyushu University, 744 Motooka, Nishi, Fukuoka 819-0395 (Japan); Adachi, Chihaya [Center for Organic Photonics and Electronics Research (OPERA), Kyushu University, 744 Motooka, Nishi, Fukuoka 819-0395 (Japan); Japan Science and Technology Agency (JST), ERATO, Adachi Molecular Exciton Engineering Project, 744 Motooka, Nishi, Fukuoka 819-0395 (Japan)
2015-11-02
We developed a thermally activated delayed fluorescence (TADF) emitter, 2,4,6-tris(4-(9,9-dimethylacridan-10-yl)phenyl)-1,3,5-triazine (3ACR-TRZ), suitable for use in solution-processed organic light-emitting diodes (OLEDs). When doped into 4,4′-bis(carbazol-9-yl)biphenyl (CBP) host at 16 wt. %, 3ACR-TRZ showed a high photoluminescence quantum yield of 98%. Transient photoluminescence decay measurements of the 16 wt. % 3ACR-TRZ:CBP film confirmed that 3ACR-TRZ exhibits efficient TADF with a triplet-to-light conversion efficiency of 96%. This high conversion efficiency makes 3ACR-TRZ attractive as an emitting dopant in OLEDs. Using 3ACR-TRZ as an emitter, we fabricated a solution-processed OLED exhibiting a maximum external quantum efficiency of 18.6%.
19. Highly Efficient Organic UV Photodetectors Based on Polyfluorene and Naphthalenediimide Blends: Effect of Thermal Annealing
Directory of Open Access Journals (Sweden)
Gorkem Memisoglu
2012-01-01
Full Text Available A solution-processed organic ultraviolet photodetector (UV-PD is introduced. The active layer of the UV-PD consists of poly(9,9-dioctyl fluorenyl-2,7–yleneethynylene (PFE and N,N′-bis-n-butyl-1,4,5,8- naphthalenediimide (BNDI with a weight ratio of 3 : 1 in chloroform. The effect of thermal annealing on the device properties was investigated from room temperature to 80∘C. The full device structure of ITO/PEDOT:PSS/PFE:BNDI (3 : 1/Al gave responsivity of 410 mA/W at −4 V under 1 mW/cm2 UV light at 368 nm when 60∘C of annealing temperature was used during its preparation. The devices that were annealed over the crystallization temperature of PFE showed a charge transfer resistance increase and a mobility decrease.
20. Thermal Stability-Enhanced and High-Efficiency Planar Perovskite Solar Cells with Interface Passivation.
Science.gov (United States)
Zhang, Weihai; Xiong, Juan; Jiang, Li; Wang, Jianying; Mei, Tao; Wang, Xianbao; Gu, Haoshuang; Daoud, Walid A; Li, Jinhua
2017-11-08
As the electron transport layer (ETL) of perovskite solar cells, oxide semiconductor zinc oxide (ZnO) has been attracting great attention due to its relatively high mobility, optical transparency, low-temperature fabrication, and good environment stability. However, the nature of ZnO will react with the patron on methylamine, which would deteriorate the performance of cells. Although many methods, including high-temperature annealing, doping, and surface modification, have been studied to improve the efficiency and stability of perovskite solar cells with ZnO ETL, devices remain relatively low in efficiency and stability. Herein, we adopted a novel multistep annealing method to deposit a porous PbI 2 film and improved the quality and uniformity of perovskite films. The cells with ZnO ETL were fabricated at the temperature of perovskite film. Interestingly, the PCE of PCBM-passivated cells could reach nearly 19.1%. To our best knowledge, this is the highest PCE value of ZnO-based perovskite solar cells until now. More importantly, PCBM modification could effectively suppress the decomposition of MAPbI 3 and improve the thermal stability of cells. Therefore, the ZnO is a promising candidate of electron transport material for perovskite solar cells in future applications.
1. A functional form-stable phase change composite with high efficiency electro-to-thermal energy conversion
International Nuclear Information System (INIS)
Wu, Wenhao; Huang, Xinyu; Li, Kai; Yao, Ruimin; Chen, Renjie; Zou, Ruqiang
2017-01-01
Graphical abstract: The thermal conductivity of PU was enhanced to 43 times of the pristine value by encapsulation in a PGF, PU@PGF can be used for highly efficient electro-to-heat energy conversion and storage with the highest energy storage efficiency up to 85%. - Highlights: • The composite exhibits an in-situ solid-solid phase change behavior. • The enthalpy of polyurethane is enhanced within the matrix. • The thermal conductivity of the composite is 43 times as much as that of the polyurethane. • Supercooling of polyurethane is greatly reduced. • The composite is applied to cold protection as a wear layer. - Abstract: A novel solid-to-solid phase change composite brick was prepared by combination of polyurethane (PU) and pitch-based graphite foam (PGF). The carbonaceous support, which can be used for mass production, not only greatly improves the thermal conductivity but promote electro-to-heat conversion efficiency of organic phase change materials (PCMs). Our composite retained the enthalpy of PCM and exhibited a greatly reduced supercooling temperature. The novel composite was investigated by differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and scanning electron microscope (SEM). The enthalpy of polyurethane has increased about 8.6% after infiltrating into graphite foam. The composite was very stable during thermal cycle test, and the electro-to-heat conversion efficiency achieves to 85% at lower voltages (1.5–1.8 V), which can vastly reduce energy consumption. The as-prepared composite was used in a wear layer to test its performance comparing with normal fabric.
2. Highly efficient exciplex organic light-emitting diodes using thermally activated delayed fluorescent emitters as donor and acceptor materials
Science.gov (United States)
Jeon, Sang Kyu; Yook, Kyoung Soo; Lee, Jun Yeob
2016-06-01
Highly efficient exciplex type organic light-emitting diodes were developed using thermally activated delayed fluorescent emitters as donors and acceptors of an exciplex. Blue emitting bis[4-(9,9-dimethyl-9,10-dihydroacridine)phenyl]sulfone (DMAC-DPS) was a donor and 9,9‧-(5-(4,6-diphenyl-1,3,5-triazin-2-yl)-1,3-phenylene)bis(9H-carbazole) (DDCzTrz) and 9,9‧,9″-(5-(4,6-diphenyl-1,3,5-triazin-2-yl)benzene-1,2,3-triyl)tris(9H-carbazole) (TCzTrz) were acceptor materials. The exciplexes of DMAC-DPS:TCzTrz and DMAC-DPS:DDCzTrz resulted in high photoluminescence quantum yield and high quantum efficiency in the green exciplex organic light-emitting diodes. High quantum efficiencies of 13.4% and 15.3% were obtained in the DMAC-DPS:DDCzTrz and DMAC-DPS:TCzTrz exciplex devices.
3. Prediction and design of efficient exciplex emitters for high-efficiency, thermally activated delayed-fluorescence organic light-emitting diodes.
Science.gov (United States)
Liu, Xiao-Ke; Chen, Zhan; Zheng, Cai-Jun; Liu, Chuan-Lin; Lee, Chun-Sing; Li, Fan; Ou, Xue-Mei; Zhang, Xiao-Hong
2015-04-08
High-efficiency, thermally activated delayed-fluorescence organic light-emitting diodes based on exciplex emitters are demonstrated. The best device, based on a TAPC:DPTPCz emitter, shows a high external quantum efficiency of 15.4%. Strategies for predicting and designing efficient exciplex emitters are also provided. This approach allow prediction and design of efficient exciplex emitters for achieving high-efficiency organic light-emitting diodes, for future use in displays and lighting applications. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
4. A highly efficient silole-containing dithienylethene with excellent thermal stability and fatigue resistance: a promising candidate for optical memory storage materials.
Science.gov (United States)
Chan, Jacky Chi-Hung; Lam, Wai Han; Yam, Vivian Wing-Wah
2014-12-10
Diarylethene compounds are potential candidates for applications in optical memory storage systems and photoswitchable molecular devices; however, they usually show low photocycloreversion quantum yields, which result in ineffective erasure processes. Here, we present the first highly efficient photochromic silole-containing dithienylethene with excellent thermal stability and fatigue resistance. The photochemical quantum yields for photocyclization and photocycloreversion of the compound are found to be high and comparable to each other; the latter of which is rarely found in diarylethene compounds. These would give rise to highly efficient photoswitchable material with effective writing and erasure processes. Incorporation of the silole moiety as a photochromic dithienylethene backbone also was demonstrated to enhance the thermal stability of the closed form, in which the thermal backward reaction to the open form was found to be negligible even at 100 °C, which leads to a promising candidate for use as photoswitchable materials and optical memory storage.
5. Separation of uranium and plutonium isotopes for measurement by multi collector inductively coupled plasma mass spectroscopy
International Nuclear Information System (INIS)
Martinelli, R.E.; Hamilton, T.F.; Kehl, S.R.; Williams, R.W.
2009-01-01
Uranium (U) and plutonium (Pu) isotopes in coral soils, contaminated by nuclear weapons testing in the northern Marshall Islands, were isolated by ion-exchange chromatography and analyzed by mass spectrometry. The soil samples were spiked with 233 U and 242 Pu tracers, dissolved in minerals acids, and U and Pu isotopes isolated and purified on commercially available ion-exchange columns. The ion-exchange technique employed a TEVA R column coupled to a UTEVA R column. U and Pu isotope fractions were then further isolated using separate elution schemes, and the purified fractions containing U and Pu isotopes analyzed sequentially using multi-collector inductively coupled plasma mass spectrometer (MCICP-MS). High precision measurements of 234 U/ 235 U, 238 U/ 235 U, 236 U/ 235 U, and 240 Pu/ 239 Pu in soil samples were attained using the described methodology and instrumentation, and provide a basis for conducting more detailed assessments of the behavior and transfer of uranium and plutonium in the environment. (author)
6. A compact E × B filter: A multi-collector cycloidal focusing mass spectrometer
Energy Technology Data Exchange (ETDEWEB)
Blase, Ryan C., E-mail: rblase@swri.edu; Miller, Greg; Brockwell, Tim; Waite, J. Hunter [Southwest Research Institute, 6220 Culebra Road, San Antonio, Texas 78238 (United States); Westlake, Joseph [The Johns Hopkins University Applied Physics Laboratory LLC, 11100 Johns Hopkins Road, Laurel, Maryland 20723 (United States); Ostrom, Nathaniel; Ostrom, Peggy H. [Department of Integrative Biology, Michigan State University, 288 Farm Lane RM 203, East Lansing, Michigan 48824 (United States)
2015-10-15
A compact E × B mass spectrometer is presented. The mass spectrometer presented is termed a “perfect focus” mass spectrometer as the resolution of the device is independent of both the initial direction and energy of the ions (spatial and energy independent). The mass spectrometer is small in size (∼10.7 in.{sup 3}) and weight (∼2 kg), making it an attractive candidate for portability when using small, permanent magnets. A multi-collector Faraday cup design allows for the detection of multiple ion beams in discrete collectors simultaneously; providing the opportunity for isotope ratio monitoring. The mass resolution of the device is around 400 through narrow collector slits and the sensitivity of the device follows expected theoretical calculations of the ion current produced in the electron impact ion source. Example mass spectra obtained from the cycloidal focusing mass spectrometer are presented as well as information on mass discrimination based on instrumental parameters and isotope ratio monitoring of certain ion signals in separate Faraday cups.
7. High-efficiency electroluminescence and amplified spontaneous emission from a thermally activated delayed fluorescent near-infrared emitter
Science.gov (United States)
Kim, Dae-Hyeon; D'Aléo, Anthony; Chen, Xian-Kai; Sandanayaka, Atula D. S.; Yao, Dandan; Zhao, Li; Komino, Takeshi; Zaborova, Elena; Canard, Gabriel; Tsuchiya, Youichi; Choi, Eunyoung; Wu, Jeong Weon; Fages, Frédéric; Brédas, Jean-Luc; Ribierre, Jean-Charles; Adachi, Chihaya
2018-02-01
Near-infrared organic light-emitting diodes and semiconductor lasers could benefit a variety of applications including night-vision displays, sensors and information-secured displays. Organic dyes can generate electroluminescence efficiently at visible wavelengths, but organic light-emitting diodes are still underperforming in the near-infrared region. Here, we report thermally activated delayed fluorescent organic light-emitting diodes that operate at near-infrared wavelengths with a maximum external quantum efficiency of nearly 10% using a boron difluoride curcuminoid derivative. As well as an effective upconversion from triplet to singlet excited states due to the non-adiabatic coupling effect, this donor-acceptor-donor compound also exhibits efficient amplified spontaneous emission. By controlling the polarity of the active medium, the maximum emission wavelength of the electroluminescence spectrum can be tuned from 700 to 780 nm. This study represents an important advance in near-infrared organic light-emitting diodes and the design of alternative molecular architectures for photonic applications based on thermally activated delayed fluorescence.
8. Structurally Deformed MoS2 for Electrochemically Stable, Thermally Resistant, and Highly Efficient Hydrogen Evolution Reaction
KAUST Repository
Chen, Yen-Chang; Lu, Ang-Yu; Lu, Ping; Yang, Xiulin; Jiang, Chang-Ming; Mariano, Marina; Kaehr, Brian; Lin, Oliver; Taylor, André ; Sharp, Ian D.; Li, Lain-Jong; Chou, Stanley S.; Tung, Vincent
2017-01-01
The emerging molybdenum disulfide (MoS2) offers intriguing possibilities for realizing a transformative new catalyst for driving the hydrogen evolution reaction (HER). However, the trade-off between catalytic activity and long-term stability represents a formidable challenge and has not been extensively addressed. This study reports that metastable and temperature-sensitive chemically exfoliated MoS2 (ce-MoS2) can be made into electrochemically stable (5000 cycles), and thermally robust (300 °C) while maintaining synthetic scalability and excellent catalytic activity through physical-transformation into 3D structurally deformed nanostructures. The dimensional transition enabled by a high throughput electrohydrodynamic process provides highly accessible, and electrochemically active surface area and facilitates efficient transport across various interfaces. Meanwhile, the hierarchically strained morphology is found to improve electronic coupling between active sites and current collecting substrates without the need for selective engineering the electronically heterogeneous interfaces. Specifically, the synergistic combination of high strain load stemmed from capillarity-induced-self-crumpling and sulfur (S) vacancies intrinsic to chemical exfoliation enables simultaneous modulation of active site density and intrinsic HER activity regardless of continuous operation or elevated temperature. These results provide new insights into how catalytic activity, electrochemical-, and thermal stability can be concurrently enhanced through the physical transformation that is reminiscent of nature, in which properties of biological materials emerge from evolved dimensional transitions.
9. Structurally Deformed MoS2 for Electrochemically Stable, Thermally Resistant, and Highly Efficient Hydrogen Evolution Reaction
KAUST Repository
Chen, Yen-Chang
2017-10-12
The emerging molybdenum disulfide (MoS2) offers intriguing possibilities for realizing a transformative new catalyst for driving the hydrogen evolution reaction (HER). However, the trade-off between catalytic activity and long-term stability represents a formidable challenge and has not been extensively addressed. This study reports that metastable and temperature-sensitive chemically exfoliated MoS2 (ce-MoS2) can be made into electrochemically stable (5000 cycles), and thermally robust (300 °C) while maintaining synthetic scalability and excellent catalytic activity through physical-transformation into 3D structurally deformed nanostructures. The dimensional transition enabled by a high throughput electrohydrodynamic process provides highly accessible, and electrochemically active surface area and facilitates efficient transport across various interfaces. Meanwhile, the hierarchically strained morphology is found to improve electronic coupling between active sites and current collecting substrates without the need for selective engineering the electronically heterogeneous interfaces. Specifically, the synergistic combination of high strain load stemmed from capillarity-induced-self-crumpling and sulfur (S) vacancies intrinsic to chemical exfoliation enables simultaneous modulation of active site density and intrinsic HER activity regardless of continuous operation or elevated temperature. These results provide new insights into how catalytic activity, electrochemical-, and thermal stability can be concurrently enhanced through the physical transformation that is reminiscent of nature, in which properties of biological materials emerge from evolved dimensional transitions.
10. Design of ortho-Substituted Donor-Acceptor Molecules as Highly Efficient Green Thermally Activated Delayed Fluorescent Emitters
Science.gov (United States)
Cha, Jae-Ryung; Gong, Myoung-Seon; Lee, Tak Jae; Ha, Tae Hoon; Lee, Chil Won
2018-04-01
The ortho-substituted donor-acceptor molecules 2-(4,6-diphenyl-1, 3, 5-triazin-2-yl)- N,Ndiphenylaniline (DPA- o-Trz) and 2-(4,6-diphenyl-1, 3, 5-triazine-2-yl)- N,N-di- p-tolylaniline (MPA- o-Trz) were designed, synthesized, and found to exhibit green fluorescence characteristics. Notably, the singlet-triplet energy gap was less than 0.1 eV, indicating that reverse intersystem crossing gave rise to thermally activated delayed fluorescence (TADF). The organic light-emitting device performance of MPA- o-Trz showed a high external quantum efficiency of 16.3% and good color stability from 0.1 cd/m2 to 5000 cd/m2.
11. Characterisation of nuclear fuel samples by quadrupole and multi-collector inductively coupled plasma mass spectrometry
International Nuclear Information System (INIS)
Wernli, Beath; Guenther-Leopold, Ines; Kobler Waldis, Judith; Kopajtic, Zlatan
2003-01-01
The characterisation of nuclear fuel cycle materials for trace and minor metallic constituents is of great interest for the nuclear industry and safeguard officials. The main objective of various international programmes dealing with postirradiation examinations is to improve the knowledge of the inventories of actinides, fission and spallation products in spent nuclear fuels. The low detection limits for a large number of elements combined with the ability to analyse the isotopic composition of the elements have established inductively coupled plasma mass spectrometry (ICP-MS) as a powerful multi-element technique in diverse analytical applications for the characterisation of nuclear materials. Because numerous isobaric overlaps restrict the direct determination of many fission products by mass spectrometry, extensive chemical separations are required for these elements. In order to simplify this sample preparation procedure, a high performance liquid chromatography system (HPLC) was online coupled to the mass spectrometer. Since about 10 years a quadrupole based ICP-MS (Q-ICP-MS) combined with an HPLC is used within the Hot Laboratory of the Paul Scherrer Institut for different applications on nuclear fuel samples. Since May 2003 also a new multi-collector ICP-MS (MC-ICP-MS) is used for the mass spectrometric characterisation of nuclear fuel samples, especially for the precise determination of the isotopic vectors of fission products and actinides. Therefore, two complementary analytical systems are now available in the group of 'Isotope and Wet Analytical Chemistry'. A comparison of the analytical performance of both systems (with and without an online coupled HPLC system) for the determination of the isotopic composition and the elemental concentration of different nuclides in nuclear fuel samples, the advantages and limitations of both techniques, the accuracy and precision of the results and typical applications for both methods will be discussed in the
12. Manipulation of Thermally Activated Delayed Fluorescence of Blue Exciplex Emission: Fully Utilizing Exciton Energy for Highly Efficient Organic Light Emitting Diodes with Low Roll-Off.
Science.gov (United States)
Wang, Zixing; Wang, Hedan; Zhu, Jun; Wu, Peng; Shen, Bowen; Dou, Dehai; Wei, Bin
2017-06-28
The application of exciplex energy has become a unique way to achieve organic light-emitting diodes (OLEDs) with high efficiencies, low turn-on voltage, and low roll-off. Novel δ-carboline derivatives with high triplet energy (T 1 ≈ 2.92 eV) and high glass transition temperature (T g ≈ 153 °C) were employed to manipulate exciplex emissions in this paper. Deep blue (peak at 436 nm) and pure blue (peak at 468 nm) thermally activated delayed fluorescence (TADF) of exciplex OLEDs were demonstrated by utilizing them as emitters with the maximum current efficiency (CE) of 4.64 cd A -1 , power efficiency (PE) of 2.91 lm W -1 , and external quantum efficiency (EQE) of 2.36%. Highly efficient blue phosphorescent OLEDs doped with FIrpic showed a maximum CE of 55.6 cd A -1 , PE of 52.9 lm W -1 , and EQE of 24.6% respectively with very low turn on voltage at 2.7 V. The devices still remain high CE of 46.5 cd A -1 at 100 cd m -2 , 45.4 cd A -1 at 1000 cd m -2 and 42.3 cd A -1 at 5000 cd m -2 with EQE close to 20% indicating low roll-off. Manipulating blue exciplex emissions by chemical structure gives an ideal strategy to fully utilize all exciton energies for lighting of OLEDs.
13. Measurement of in situ sulfur isotopes by laser ablation multi-collector ICPMS: opening Pandora’s Box
Science.gov (United States)
Ridley, William I.; Pribil, Michael; Koenig, Alan E.; Slack, John F.
2015-01-01
Laser ablation multi-collector ICPMS is a modern tool for in situ measurement of S isotopes. Advantages of the technique are speed of analysis and relatively minor matrix effects combined with spatial resolution sufficient for many applications. The main disadvantage is a more destructive sampling mechanism relative to the ion microprobe technique. Recent advances in instrumentation allow precise measurement with spatial resolutions down to 25 microns. We describe specific examples from economic geology where increased spatial resolution has greatly expanded insights into the sources and evolution of fluids that cause mineralization and illuminated genetic relations between individual deposits in single mineral districts.
14. Coupling between chip based isotachophoresis and multi-collector inductively coupled plasma mass spectrometry for separation and measurement of lanthanides
International Nuclear Information System (INIS)
Vio, Laurent; Cretier, Gerard; Rocca, Jean-Louis; Chartier, Frederic; Geertsen, Valerie; Gourgiotis, Alkiviadis; Isnard, Helene; Morin, Pierre
2012-01-01
This paper presents the conception and fabrication of a micro-system for lanthanides separation and its coupling with a multi-collector inductively coupled plasma mass spectrometer for isotope ratio measurements. The lanthanides separation is based on the isotachophoresis technique and the micro-system conception has been adapted in order to fit with glove box limitations in view of future spent nuclear fuels analysis. The micro-device was tested by using a mixture of standard solutions of natural elements and the separation of 13 lanthanides was successfully performed. The micro-device was then coupled to a multi-collector inductively coupled plasma mass spectrometer for the on-line measurements of Nd and Sm isotope ratios. The isotopes of Nd and Sm were acquired online in multi-collection mode after separation of the two elements with an injection amount of 5 ng. Results obtained on the Nd and Sm isotope ratio measurements on transient signals are presented and discussed. (authors)
15. Reduction of determinate errors in mass bias-corrected isotope ratios measured using a multi-collector plasma mass spectrometer
International Nuclear Information System (INIS)
Doherty, W.
2015-01-01
A nebulizer-centric instrument response function model of the plasma mass spectrometer was combined with a signal drift model, and the result was used to identify the causes of the non-spectroscopic determinate errors remaining in mass bias-corrected Pb isotope ratios (Tl as internal standard) measured using a multi-collector plasma mass spectrometer. Model calculations, confirmed by measurement, show that the detectable time-dependent errors are a result of the combined effect of signal drift and differences in the coordinates of the Pb and Tl response function maxima (horizontal offset effect). If there are no horizontal offsets, then the mass bias-corrected isotope ratios are approximately constant in time. In the absence of signal drift, the response surface curvature and horizontal offset effects are responsible for proportional errors in the mass bias-corrected isotope ratios. The proportional errors will be different for different analyte isotope ratios and different at every instrument operating point. Consequently, mass bias coefficients calculated using different isotope ratios are not necessarily equal. The error analysis based on the combined model provides strong justification for recommending a three step correction procedure (mass bias correction, drift correction and a proportional error correction, in that order) for isotope ratio measurements using a multi-collector plasma mass spectrometer
16. Fiscal 1997 survey report. Preparatory survey for a manual on the introduction of high efficiency thermal utilization systems; 1997 nendo chosa hokokusho. Kokoritsu netsu riyo system donyu manual no sakusei choa
Energy Technology Data Exchange (ETDEWEB)
NONE
1998-03-01
To cope with the energy issue and global environmental issue, it is necessary to forcibly promote energy conservation. In the light of the present situation that in Japan only 1/3 of the primary energy consumed is effectively used, policies are being prepared for promotion of the introduction of high efficiency thermal utilization systems including a project for formation of the environmentally friendly type energy community promoted by NEDO. However, it is hard to say that the introduction is being actively promoted. The cause is that they do not fully understood the present status of high efficiency thermal utilization systems, procedures for introduction, subsidy system, etc. Therefore, a manual was made to present to self governments and enterprisers who are planning to introduce the system. To be concrete, there are the six systems: cogeneration use thermal supply system, unused energy use thermal supply system, heat storage use thermal supply system, waste use thermal supply system, plant surplus energy use thermal supply system, and cascade type thermal supply system. 28 refs., 38 figs., 42 tabs.
17. HIGH EFFICIENCY TURBINE
OpenAIRE
VARMA, VIJAYA KRUSHNA
2012-01-01
Varma designed ultra modern and high efficiency turbines which can use gas, steam or fuels as feed to produce electricity or mechanical work for wide range of usages and applications in industries or at work sites. Varma turbine engines can be used in all types of vehicles. These turbines can also be used in aircraft, ships, battle tanks, dredgers, mining equipment, earth moving machines etc, Salient features of Varma Turbines. 1. Varma turbines are simple in design, easy to manufac...
18. Ultra-trace determination of plutonium in marine samples using multi-collector inductively coupled plasma mass spectrometry.
Science.gov (United States)
Lindahl, Patric; Keith-Roach, Miranda; Worsfold, Paul; Choi, Min-Seok; Shin, Hyung-Seon; Lee, Sang-Hoon
2010-06-25
Sources of plutonium isotopes to the marine environment are well defined, both spatially and temporally, which makes Pu a potential tracer for oceanic processes. This paper presents the selection, optimisation and validation of a sample preparation method for the ultra-trace determination of Pu isotopes ((240)Pu and (239)Pu) in marine samples by multi-collector (MC) ICP-MS. The method was optimised for the removal of the interference from (238)U and the chemical recovery of Pu. Comparison of various separation strategies using AG1-X8, TEVA, TRU, and UTEVA resins to determine Pu in marine calcium carbonate samples is reported. A combination of anion-exchange (AG1-X8) and extraction chromatography (UTEVA/TRU) was the most suitable, with a radiochemical Pu yield of 87+/-5% and a U decontamination factor of 1.2 x 10(4). Validation of the method was accomplished by determining Pu in various IAEA certified marine reference materials. The estimated MC-ICP-MS instrumental limit of detection for (239)Pu and (240)Pu was 0.02 fg mL(-1), with an absolute limit of quantification of 0.11 fg. The proposed method allows the determination of ultra-trace Pu, at femtogram levels, in small size marine samples (e.g., 0.6-2.0 g coral or 15-20 L seawater). Finally, the analytical method was applied to determining historical records of the Pu signature in coral samples from the tropical Northwest Pacific and (239+240)Pu concentrations and (240)Pu/(239)Pu atom ratios in seawater samples as part of the 2008 GEOTRACES intercalibration exercise. Copyright 2010 Elsevier B.V. All rights reserved.
19. Ultra-trace determination of plutonium in marine samples using multi-collector inductively coupled plasma mass spectrometry
Energy Technology Data Exchange (ETDEWEB)
Lindahl, Patric, E-mail: patriclindahl@yahoo.com [Marine Environment Research Department, Korea Ocean Research and Development Institute, 1270 Sadong, Ansan 426-744 (Korea, Republic of); School of Geography, Earth and Environmental Sciences, University of Plymouth, Drake Circus, Plymouth PL48AA (United Kingdom); Keith-Roach, Miranda; Worsfold, Paul [School of Geography, Earth and Environmental Sciences, University of Plymouth, Drake Circus, Plymouth PL48AA (United Kingdom); Choi, Min-Seok; Shin, Hyung-Seon [Division of Earth and Environmental Science, Korea Basic Science Institute, 113 Gwahangno, Yusung-gu, Daejon 305-333 (Korea, Republic of); Lee, Sang-Hoon [Marine Geology and Geophysics Laboratory, Korea Ocean Research and Development Institute, 1270 Sadong, Ansan 426-744 (Korea, Republic of)
2010-06-25
Sources of plutonium isotopes to the marine environment are well defined, both spatially and temporally, which makes Pu a potential tracer for oceanic processes. This paper presents the selection, optimisation and validation of a sample preparation method for the ultra-trace determination of Pu isotopes ({sup 240}Pu and {sup 239}Pu) in marine samples by multi-collector (MC) ICP-MS. The method was optimised for the removal of the interference from {sup 238}U and the chemical recovery of Pu. Comparison of various separation strategies using AG1-X8, TEVA, TRU, and UTEVA resins to determine Pu in marine calcium carbonate samples is reported. A combination of anion-exchange (AG1-X8) and extraction chromatography (UTEVA/TRU) was the most suitable, with a radiochemical Pu yield of 87 {+-} 5% and a U decontamination factor of 1.2 x 10{sup 4}. Validation of the method was accomplished by determining Pu in various IAEA certified marine reference materials. The estimated MC-ICP-MS instrumental limit of detection for {sup 239}Pu and {sup 240}Pu was 0.02 fg mL{sup -1}, with an absolute limit of quantification of 0.11 fg. The proposed method allows the determination of ultra-trace Pu, at femtogram levels, in small size marine samples (e.g., 0.6-2.0 g coral or 15-20 L seawater). Finally, the analytical method was applied to determining historical records of the Pu signature in coral samples from the tropical Northwest Pacific and {sup 239+240}Pu concentrations and {sup 240}Pu/{sup 239}Pu atom ratios in seawater samples as part of the 2008 GEOTRACES intercalibration exercise.
20. Ultra-trace determination of plutonium in marine samples using multi-collector inductively coupled plasma mass spectrometry
International Nuclear Information System (INIS)
Lindahl, Patric; Keith-Roach, Miranda; Worsfold, Paul; Choi, Min-Seok; Shin, Hyung-Seon; Lee, Sang-Hoon
2010-01-01
Sources of plutonium isotopes to the marine environment are well defined, both spatially and temporally, which makes Pu a potential tracer for oceanic processes. This paper presents the selection, optimisation and validation of a sample preparation method for the ultra-trace determination of Pu isotopes ( 240 Pu and 239 Pu) in marine samples by multi-collector (MC) ICP-MS. The method was optimised for the removal of the interference from 238 U and the chemical recovery of Pu. Comparison of various separation strategies using AG1-X8, TEVA, TRU, and UTEVA resins to determine Pu in marine calcium carbonate samples is reported. A combination of anion-exchange (AG1-X8) and extraction chromatography (UTEVA/TRU) was the most suitable, with a radiochemical Pu yield of 87 ± 5% and a U decontamination factor of 1.2 x 10 4 . Validation of the method was accomplished by determining Pu in various IAEA certified marine reference materials. The estimated MC-ICP-MS instrumental limit of detection for 239 Pu and 240 Pu was 0.02 fg mL -1 , with an absolute limit of quantification of 0.11 fg. The proposed method allows the determination of ultra-trace Pu, at femtogram levels, in small size marine samples (e.g., 0.6-2.0 g coral or 15-20 L seawater). Finally, the analytical method was applied to determining historical records of the Pu signature in coral samples from the tropical Northwest Pacific and 239+240 Pu concentrations and 240 Pu/ 239 Pu atom ratios in seawater samples as part of the 2008 GEOTRACES intercalibration exercise.
1. High-efficiency CARM
Energy Technology Data Exchange (ETDEWEB)
Bratman, V.L.; Kolchugin, B.D.; Samsonov, S.V.; Volkov, A.B. [Institute of Applied Physics, Nizhny Novgorod (Russian Federation)
1995-12-31
The Cyclotron Autoresonance Maser (CARM) is a well-known variety of FEMs. Unlike the ubitron in which electrons move in a periodical undulator field, in the CARM the particles move along helical trajectories in a uniform magnetic field. Since it is much simpler to generate strong homogeneous magnetic fields than periodical ones for a relatively low electron energy ({Brit_pounds}{le}1-3 MeV) the period of particles trajectories in the CARM can be sufficiently smaller than in the undulator in which, moreover, the field decreases rapidly in the transverse direction. In spite of this evident advantage, the number of papers on CARM is an order less than on ubitron, which is apparently caused by the low (not more than 10 %) CARM efficiency in experiments. At the same time, ubitrons operating in two rather complicated regimes-trapping and adiabatic deceleration of particles and combined undulator and reversed guiding fields - yielded efficiencies of 34 % and 27 %, respectively. The aim of this work is to demonstrate that high efficiency can be reached even for a simplest version of the CARM. In order to reduce sensitivity to an axial velocity spread of particles, a short interaction length where electrons underwent only 4-5 cyclotron oscillations was used in this work. Like experiments, a narrow anode outlet of a field-emission electron gun cut out the {open_quotes}most rectilinear{close_quotes} near-axis part of the electron beam. Additionally, magnetic field of a small correcting coil compensated spurious electron oscillations pumped by the anode aperture. A kicker in the form of a sloping to the axis frame with current provided a control value of rotary velocity at a small additional velocity spread. A simple cavity consisting of a cylindrical waveguide section restricted by a cut-off waveguide on the cathode side and by a Bragg reflector on the collector side was used as the CARM-oscillator microwave system.
2. Scalable, "Dip-and-Dry" Fabrication of a Wide-Angle Plasmonic Selective Absorber for High-Efficiency Solar-Thermal Energy Conversion.
Science.gov (United States)
Mandal, Jyotirmoy; Wang, Derek; Overvig, Adam C; Shi, Norman N; Paley, Daniel; Zangiabadi, Amirali; Cheng, Qian; Barmak, Katayun; Yu, Nanfang; Yang, Yuan
2017-11-01
A galvanic-displacement-reaction-based, room-temperature "dip-and-dry" technique is demonstrated for fabricating selectively solar-absorbing plasmonic-nanoparticle-coated foils (PNFs). The technique, which allows for facile tuning of the PNFs' spectral reflectance to suit different radiative and thermal environments, yields PNFs which exhibit excellent, wide-angle solar absorptance (0.96 at 15°, to 0.97 at 35°, to 0.79 at 80°), and low hemispherical thermal emittance (0.10) without the aid of antireflection coatings. The thermal emittance is on par with those of notable selective solar absorbers (SSAs) in the literature, while the wide-angle solar absorptance surpasses those of previously reported SSAs with comparable optical selectivities. In addition, the PNFs show promising mechanical and thermal stabilities at temperatures of up to 200 °C. Along with the performance of the PNFs, the simplicity, inexpensiveness, and environmental friendliness of the "dip-and-dry" technique makes it an appealing alternative to current methods for fabricating selective solar absorbers. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
3. Thermal battery with CO2 compression heat pump: Techno-economic optimization of a high-efficiency Smart Grid option for buildings
DEFF Research Database (Denmark)
Blarke, Morten; Yazawa, Kazuaki; Shakouri, Ali
2012-01-01
Increasing penetration levels of wind and solar power in the energy system call for the development of Smart Grid enabling technologies. As an alternative to expensive electro-chemical and mechanical storage options, the thermal energy demand in buildings offers a cost-effective option for interm......Increasing penetration levels of wind and solar power in the energy system call for the development of Smart Grid enabling technologies. As an alternative to expensive electro-chemical and mechanical storage options, the thermal energy demand in buildings offers a cost-effective option....... In a proof-of-concept case study, the TB replaces an existing electric resistance heater used for hot water production and an electric compressor used for air refrigeration in a central air conditioning system. A mathematical model for least-cost unit dispatch is developed. Heat pump cycle components...
4. Realizing Highly Efficient Solution-Processed Homojunction-Like Sky-Blue OLEDs by Using Thermally Activated Delayed Fluorescent Emitters Featuring an Aggregation-Induced Emission Property.
Science.gov (United States)
Wu, Kailong; Wang, Zian; Zhan, Lisi; Zhong, Cheng; Gong, Shaolong; Xie, Guohua; Yang, Chuluo
2018-04-05
Two new blue emitters, i.e., bis-[2-(9,9-dimethyl-9,10-dihydroacridine)-phenyl]-sulfone ( o-ACSO2) and bis-[3-(9,9-dimethyl-9,10-dihydroacridine)-phenyl]-sulfone ( m-ACSO2), with reserved fine thermally activated delayed fluorescent (TADF) nature and simply tuned thermal and optoelectronic properties, were synthesized by isomer engineering. The meta-linking compound, i.e., m-ACSO2, obtains the highest photoluminescence quantum yield with a small singlet-triplet energy gap, a moderate delayed fluorescent lifetime, excellent solubility, and neat film homogeneity. Due to its unique aggregation-induced emission (AIE) character, neat film-based heterojunction-like organic light-emitting diodes (OLEDs) are achievable. By inserting an excitonic inert exciton-blocking layer, the PN heterojunction-like emission accompanied by intefacial exciplex was shifted to a homojunction-like channel mainly from the AIE emitter itself, providing a new tactic to generate efficient blue color from neat films. The solution-processed nondoped sky-blue OLED employing m-ACSO2 as emitter with homojunction-like emission achieved a maximum external quantum efficiency of 17.2%. The design strategies presented herein provide practical methods to construct efficient blue TADF dyes and realize high-performance blue TADF devices.
5. In-Space technology experiments program. A high efficiency thermal interface (using condensation heat transfer) between a 2-phase fluid loop and heatpipe radiator: Experiment definition phase
Science.gov (United States)
Pohner, John A.; Dempsey, Brian P.; Herold, Leroy M.
1990-01-01
Space Station elements and advanced military spacecraft will require rejection of tens of kilowatts of waste heat. Large space radiators and two-phase heat transport loops will be required. To minimize radiator size and weight, it is critical to minimize the temperature drop between the heat source and sink. Under an Air Force contract, a unique, high-performance heat exchanger is developed for coupling the radiator to the transport loop. Since fluid flow through the heat exchanger is driven by capillary forces which are easily dominated by gravity forces in ground testing, it is necessary to perform microgravity thermal testing to verify the design. This contract consists of an experiment definition phase leading to a preliminary design and cost estimate for a shuttle-based flight experiment of this heat exchanger design. This program will utilize modified hardware from a ground test program for the heat exchanger.
6. Commissioning and operating experiences with high-efficiency, environmentally acceptable brown coal thermal power units; Inbetriebsetzung und Betriebserfahrungen mit hoch effizienten und umweltfreundlichen Braunkohlebloecken
Energy Technology Data Exchange (ETDEWEB)
Kehr, M.; Mandel, H.; Kather, A.
1998-12-31
The generation system of VEAG had a power output 15,000 MW, of which 82%, or 12,700 MW, came from brown coal power plants that had no flue gas desulphurisation and insufficient flue gas dedusting facilities. One of the major goals of the companys programme for enhancing the economic efficiency and public acceptance of the conversion of brown coal to electricity was to achieve a net power plant efficiency of 40%. In the case of the KW Schwarze Pumpe project this was achieved by the use of supercritical steam parameters, installation of a flue gas heat recovery system, and the optimisation of the cold end of the turbine by allowing for a condenser pressure of 40 mbar and by connecting condensers in series. Further effects were achieved by fine adjustments to the thermal circuitry. [Deutsch] Der Kraftwerkspark der VEAG umfasste 15.400 MW und bestand mit 12.700 MW zu 82% aus Braunkohlekraftwerken, die ueber keine Rauchgasentschwefelung und unzureichende Entstaubungsanlagen im Rauchgas verfuegten. Als wesentliche Forderung zur Erhoehung der Wirtschaftlichkeit und Akzeptanz der Braunkohleverstromung wurde die Forderung nach Erreichen eines Netto-Kraftwerkswirkungsgrades von 40% gestellt. Fuer das Projekt KW Schwarze Pumpe wurde neben der Anwendung der ueberkritschen Dampfparameter zur Sicherung der Zielstellung eines Wirkungsgrades von mindestens 40% der Einbau einer Rauchgaswaermenutzung und die Optimierung des kalten Endes der Turbine mit Auslegung fuer einen Kondensatordruck von 40 mbar sowie Reihenschaltung der Kondensatoren festgelegt. Weitere Effekte wurden durch Feinoptimierung des Waermeschaltbildes erreicht. (orig.)
7. Precise Monitoring of Depleted Uranium in human and environment of South Iraq using Multi-collector ICP-MS
Energy Technology Data Exchange (ETDEWEB)
Gerdes, A.; Weyer, S.; Brey, G. [Frankfurt Univ., Dept. of Mineralogy (Germany); Zimmermann, I.; Durakovic, A. [Uranium Medical Research Centre, Toronto (Italy)
2004-07-01
Multi-collector Inductive Coupled Plasma Mass Spectrometry (MC-ICPMS) becomes increasingly important in monitoring environmental contamination, because it allows detection of long-lived radionuclides at ultra trace levels. High sample throughout combined with high precision and accuracy, low detection limits for most elements and simultaneous detection of up to 9 isotopes makes it prior to most other techniques. For homogeneous samples concentration and isotope composition can be determined with a precision and uncertainty of usually better than 0.5 % using the isotope dilution method, e.g. isotope measurements relative to a well characterized {sup 233}U tracer. Exposure to low-level radioactive dust released into the environment accidentally or by the use of Depleted Uranium (DU) munitions in the military theatre demands precise screening of humans and local environment. Sensitive methods are also needed for monitoring and understanding the pathway of radionuclides in the biosphere and the human body. Using a method recently developed at our department it is for instance possible to detect urinary excretion of DU in the low fg/ml range or at fractions below 0.2% of the total urinary uranium concentration. This allows monitoring the inhalation of up to a few micrograms of insoluble non-natural uranium particles in the lung several months or even years later. As example we will show and discuss results from our study of the uranium isotope composition and concentration of surface water, topsoil and dust from different sites of Baghdad, Basra, and the Suweirah farming area. We also analyzed urine from people living in these areas or stayed their for a relative short time. The samples, also including highly contaminated ones, such as wipes of tank top debris and penetrator channels, were collected from the Uranium Medical Research Centre field team after coalition operation Iraqi Freedom in early October 2003. Total soil samples, separated soil fine-fractions (< 100
8. Precise Monitoring of Depleted Uranium in human and environment of South Iraq using Multi-collector ICP-MS
International Nuclear Information System (INIS)
Gerdes, A.; Weyer, S.; Brey, G.; Zimmermann, I.; Durakovic, A.
2004-01-01
Multi-collector Inductive Coupled Plasma Mass Spectrometry (MC-ICPMS) becomes increasingly important in monitoring environmental contamination, because it allows detection of long-lived radionuclides at ultra trace levels. High sample throughout combined with high precision and accuracy, low detection limits for most elements and simultaneous detection of up to 9 isotopes makes it prior to most other techniques. For homogeneous samples concentration and isotope composition can be determined with a precision and uncertainty of usually better than 0.5 % using the isotope dilution method, e.g. isotope measurements relative to a well characterized 233 U tracer. Exposure to low-level radioactive dust released into the environment accidentally or by the use of Depleted Uranium (DU) munitions in the military theatre demands precise screening of humans and local environment. Sensitive methods are also needed for monitoring and understanding the pathway of radionuclides in the biosphere and the human body. Using a method recently developed at our department it is for instance possible to detect urinary excretion of DU in the low fg/ml range or at fractions below 0.2% of the total urinary uranium concentration. This allows monitoring the inhalation of up to a few micrograms of insoluble non-natural uranium particles in the lung several months or even years later. As example we will show and discuss results from our study of the uranium isotope composition and concentration of surface water, topsoil and dust from different sites of Baghdad, Basra, and the Suweirah farming area. We also analyzed urine from people living in these areas or stayed their for a relative short time. The samples, also including highly contaminated ones, such as wipes of tank top debris and penetrator channels, were collected from the Uranium Medical Research Centre field team after coalition operation Iraqi Freedom in early October 2003. Total soil samples, separated soil fine-fractions ( 233 U
9. Evaluating the accuracy of uranium isotope amount ratio measurements performed by a quadrupole and a multi-collector magnetic sector inductively coupled plasma mass spectrometers for nuclear safeguards
International Nuclear Information System (INIS)
Pereira de Oliveira, O. Jr.; Sarkis, J.E.S.; Ponzevera, E.; Alonso, A.; De Bolle, W.; Quetel, C.
2008-01-01
The n(U 235 )/n(U 238 ) isotope amount ratio in a set of samples was measured using two modern analytical techniques: quadrupole inductively coupled plasma mass spectrometry (ICP-QMS) and multi-collector magnetic sector inductively coupled plasma mass spectrometry (MC-ICPMS). The measured ratios were compared to the certified ratios provided by the high accuracy gas source mass spectrometry (GSMS). The components of the uncertainty were identified and their contribution to the combined standard uncertainty was estimated using the recommendations of the ISO-GUM guide. The values of the measurement uncertainty and bias were determined and then compared to the International Target Values for Measurement Uncertainties in Safeguarding Nuclear Materials. It appears that only the measurements performed by MC-ICPMS can meet the stringent requirements of international nuclear safeguards. (authors)
10. New highly efficient piezoceramic materials
International Nuclear Information System (INIS)
Dantsiger, A.Ya.; Razumovskaya, O.N.; Reznichenko, L.A.; Grineva, L.D.; Devlikanova, R.U.; Dudkina, S.I.; Gavrilyachenko, S.V.; Dergunova, N.V.
1993-01-01
New high efficient piezoceramic materials with various combination of parameters inclusing high Curie point for high-temperature transducers using in atomic power engineering are worked. They can be used in systems for heated matters nondestructive testing, controllers for varied industrial power plants and other high-temperature equipment
11. Unconventional, High-Efficiency Propulsors
DEFF Research Database (Denmark)
Andersen, Poul
1996-01-01
The development of ship propellers has generally been characterized by search for propellers with as high efficiency as possible and at the same time low noise and vibration levels and little or no cavitation. This search has lead to unconventional propulsors, like vane-wheel propulsors, contra-r...
12. Overview of Ecological Agriculture with High Efficiency
OpenAIRE
Huang, Guo-qin; Zhao, Qi-guo; Gong, Shao-lin; Shi, Qing-hua
2012-01-01
From the presentation, connotation, characteristics, principles, pattern, and technologies of ecological agriculture with high efficiency, we conduct comprehensive and systematic analysis and discussion of the theoretical and practical progress of ecological agriculture with high efficiency. (i) Ecological agriculture with high efficiency was first advanced in China in 1991. (ii) Ecological agriculture with high efficiency highlights "high efficiency", "ecology", and "combination". (iii) Ecol...
13. Non-linear signal response functions and their effects on the statistical and noise cancellation properties of isotope ratio measurements by multi-collector plasma mass spectrometry
International Nuclear Information System (INIS)
Doherty, W.
2013-01-01
A nebulizer-centric response function model of the analytical inductively coupled argon plasma ion source was used to investigate the statistical frequency distributions and noise reduction factors of simultaneously measured flicker noise limited isotope ion signals and their ratios. The response function model was extended by assuming i) a single gaussian distributed random noise source (nebulizer gas pressure fluctuations) and ii) the isotope ion signal response is a parabolic function of the nebulizer gas pressure. Model calculations of ion signal and signal ratio histograms were obtained by applying the statistical method of translation to the non-linear response function model of the plasma. Histograms of Ni, Cu, Pr, Tl and Pb isotope ion signals measured using a multi-collector plasma mass spectrometer were, without exception, negative skew. Histograms of the corresponding isotope ratios of Ni, Cu, Tl and Pb were either positive or negative skew. There was a complete agreement between the measured and model calculated histogram skew properties. The nebulizer-centric response function model was also used to investigate the effect of non-linear response functions on the effectiveness of noise cancellation by signal division. An alternative noise correction procedure suitable for parabolic signal response functions was derived and applied to measurements of isotope ratios of Cu, Ni, Pb and Tl. The largest noise reduction factors were always obtained when the non-linearity of the response functions was taken into account by the isotope ratio calculation. Possible applications of the nebulizer-centric response function model to other types of analytical instrumentation, large amplitude signal noise sources (e.g., lasers, pumped nebulizers) and analytical error in isotope ratio measurements by multi-collector plasma mass spectrometry are discussed. - Highlights: ► Isotope ion signal noise is modelled as a parabolic transform of a gaussian variable. ► Flicker
14. High Efficiency Room Air Conditioner
Energy Technology Data Exchange (ETDEWEB)
Bansal, Pradeep [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
2015-01-01
This project was undertaken as a CRADA project between UT-Battelle and Geberal Electric Company and was funded by Department of Energy to design and develop of a high efficiency room air conditioner. A number of novel elements were investigated to improve the energy efficiency of a state-of-the-art WAC with base capacity of 10,000 BTU/h. One of the major modifications was made by downgrading its capacity from 10,000 BTU/hr to 8,000 BTU/hr by replacing the original compressor with a lower capacity (8,000 BTU/hr) but high efficiency compressor having an EER of 9.7 as compared with 9.3 of the original compressor. However, all heat exchangers from the original unit were retained to provide higher EER. The other subsequent major modifications included- (i) the AC fan motor was replaced by a brushless high efficiency ECM motor along with its fan housing, (ii) the capillary tube was replaced with a needle valve to better control the refrigerant flow and refrigerant set points, and (iii) the unit was tested with a drop-in environmentally friendly binary mixture of R32 (90% molar concentration)/R125 (10% molar concentration). The WAC was tested in the environmental chambers at ORNL as per the design rating conditions of AHAM/ASHRAE (Outdoor- 95F and 40%RH, Indoor- 80F, 51.5%RH). All these modifications resulted in enhancing the EER of the WAC by up to 25%.
15. High-efficient electron linacs
International Nuclear Information System (INIS)
Glavatskikh, K.V.; Zverev, B.V.; Kalyuzhnyj, V.E.; Morozov, V.L.; Nikolaev, S.V.; Plotnikov, S.N.; Sobenin, N.P.; Vovna, V.A.; Gryzlov, A.V.
1993-01-01
Comparison analysis of ELA on running and still waves designed for 10 MeV energy and with high efficiency is carried out. It is shown, that from the point of view of dimensions ELA with a still wave or that of a combined type is more preferable. From the point of view of impedance characteristics in any variant with application of magnetron as HF-generator it is necessary to implement special requirements to the accelerating structure if no ferrite isolation is provided in HF-channel. 3 refs., 4 figs., 1 tab
16. Separation of Platinum from Palladium and Iridium in Iron Meteorites and Accurate High-Precision Determination of Platinum Isotopes by Multi-Collector ICP-MS.
Science.gov (United States)
Hunt, Alison C; Ek, Mattias; Schönbächler, Maria
2017-12-01
This study presents a new measurement procedure for the isolation of Pt from iron meteorite samples. The method also allows for the separation of Pd from the same sample aliquot. The separation entails a two-stage anion-exchange procedure. In the first stage, Pt and Pd are separated from each other and from major matrix constituents including Fe and Ni. In the second stage, Ir is reduced with ascorbic acid and eluted from the column before Pt collection. Platinum yields for the total procedure were typically 50-70%. After purification, high-precision Pt isotope determinations were performed by multi-collector ICP-MS. The precision of the new method was assessed using the IIAB iron meteorite North Chile. Replicate analyses of multiple digestions of this material yielded an intermediate precision for the measurement results of 0.73 for ε 192 Pt, 0.15 for ε 194 Pt and 0.09 for ε 196 Pt (2 standard deviations). The NIST SRM 3140 Pt solution reference material was passed through the measurement procedure and yielded an isotopic composition that is identical to the unprocessed Pt reference material. This indicates that the new technique is unbiased within the limit of the estimated uncertainties. Data for three iron meteorites support that Pt isotope variations in these samples are due to exposure to galactic cosmic rays in space.
17. High efficiency turbine blade coatings
Energy Technology Data Exchange (ETDEWEB)
Youchison, Dennis L. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Gallis, Michail A. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
2014-06-01
18. High-efficiency photovoltaic cells
Science.gov (United States)
Yang, H.T.; Zehr, S.W.
1982-06-21
High efficiency solar converters comprised of a two cell, non-lattice matched, monolithic stacked semiconductor configuration using optimum pairs of cells having bandgaps in the range 1.6 to 1.7 eV and 0.95 to 1.1 eV, and a method of fabrication thereof, are disclosed. The high band gap subcells are fabricated using metal organic chemical vapor deposition (MOCVD), liquid phase epitaxy (LPE) or molecular beam epitaxy (MBE) to produce the required AlGaAs layers of optimized composition, thickness and doping to produce high performance, heteroface homojunction devices. The low bandgap subcells are similarly fabricated from AlGa(As)Sb compositions by LPE, MBE or MOCVD. These subcells are then coupled to form a monolithic structure by an appropriate bonding technique which also forms the required transparent intercell ohmic contact (IOC) between the two subcells. Improved ohmic contacts to the high bandgap semiconductor structure can be formed by vacuum evaporating to suitable metal or semiconductor materials which react during laser annealing to form a low bandgap semiconductor which provides a low contact resistance structure.
19. Fit for purpose validated method for the determination of the strontium isotopic signature in mineral water samples by multi-collector inductively coupled plasma mass spectrometry
Energy Technology Data Exchange (ETDEWEB)
Brach-Papa, Christophe; Van Bocxstaele, Marleen; Ponzevera, Emmanuel [European Commission - Joint Research Centre - Institute for Reference Materials and Measurements, Retieseweg 111 - 2440 Geel (Belgium); Quetel, Christophe R. [European Commission - Joint Research Centre - Institute for Reference Materials and Measurements, Retieseweg 111 - 2440 Geel (Belgium)], E-mail: christophe.quetel@ec.europa.eu
2009-03-15
A robust method allowing the routine determination of n({sup 87}Sr)/n({sup 86}Sr) with at least five significant decimal digits for large sets of mineral water samples is described. It is based on 2 consecutive chromatographic separations of Sr associated to multi-collector inductively coupled plasma mass spectrometry (MC-ICPMS) measurements. Separations are performed using commercial pre-packed columns filled with 'Sr resin' to overcome isobaric interferences affecting the determination of strontium isotope ratios. The careful method validation scheme applied is described. It included investigations on all parameters influencing both chromatographic separations and MC-ICPMS measurements, and also the test on a synthetic sample made of an aliquot of the NIST SRM 987 certified reference material dispersed in a saline matrix to mimic complex samples. Correction for mass discrimination was done internally using the n({sup 88}Sr)/n({sup 86}Sr) ratio. For comparing mineral waters originating from different geological backgrounds or identifying counterfeits, calculations involved the well known consensus value (1/0.1194) {+-} 0 as reference. The typical uncertainty budget estimated for these results was 40 'ppm' relative (k = 2). It increased to 150 'ppm' (k = 2) for the establishment of stand alone results, taking into account a relative difference of about 126 'ppm' systematically observed between measured and certified values of the NIST SRM 987. In case there was suspicion of a deviation of the n({sup 88}Sr)/n({sup 86}Sr) ratio (worst case scenario) our proposal was to use the NIST SRM 987 value 8.37861 {+-} 0.00325 (k = 2) as reference, and assign a typical relative uncertainty budget of 300 'ppm' (k = 2). This method is thus fit for purpose and was applied to eleven French samples.
20. Validation of the determination of the B isotopic composition in Roman glasses with laser ablation multi-collector inductively coupled plasma-mass spectrometry
International Nuclear Information System (INIS)
Devulder, Veerle; Gerdes, Axel; Vanhaecke, Frank; Degryse, Patrick
2015-01-01
The applicability of laser ablation multi-collector inductively coupled plasma-mass spectrometry (LA-MC-ICP-MS) for the determination of the B isotopic composition in Roman glasses was investigated. The δ 11 B values thus obtained provide information on the natron flux used during the glass-making process. The glass samples used for this purpose were previously characterized using pneumatic nebulization (PN) MC-ICP-MS. Unfortunately, this method is time-consuming and labor-intensive and consumes some 100 mg of sample, which is a rather high amount for ancient materials. Therefore, the use of the less invasive and faster LA-MC-ICP-MS approach was explored. In this work, the results for 29 Roman glasses and 4 home-made glasses obtained using both techniques were compared to assess the suitability of LA-MC-ICP-MS in this context. The results are in excellent agreement within experimental uncertainty. No difference in overall mass discrimination was observed between the Roman glasses, NIST SRM 610 reference glass and B6 obsidian. The expanded uncertainty of the LA-MC-ICP-MS approach was estimated to be < 2‰, which is similar to that obtained upon sample digestion and PN-MC-ICP-MS measurement. - Highlights: • First use of LA-MC-ICP-MS for B isotopic analysis of ancient glass • Careful validation of LA-MC-ICP-MS approach • Similar precision & accuracy via solution MC-ICP-MS after isolation of B • Enhancement of sample throughput & reduction of sample consumption • Improved conditions for archeometric research on (pre-)Roman glass
1. Validation of the determination of the B isotopic composition in Roman glasses with laser ablation multi-collector inductively coupled plasma-mass spectrometry
Energy Technology Data Exchange (ETDEWEB)
Devulder, Veerle [Department of Analytical Chemistry, Ghent University, Krijgslaan 281-S12, 9000 Ghent (Belgium); Department of Earth and Environmental Sciences, Katholieke Universiteit Leuven, Celestijnenlaan 200 E-box 2408, 3001 Leuven (Belgium); Gerdes, Axel [Institute of Geoscience, Goethe Universität, Altenhoeferallee 1, 60438 Frankfurt am Main (Germany); Vanhaecke, Frank, E-mail: Frank.Vanhaecke@UGent.be [Department of Analytical Chemistry, Ghent University, Krijgslaan 281-S12, 9000 Ghent (Belgium); Degryse, Patrick [Department of Earth and Environmental Sciences, Katholieke Universiteit Leuven, Celestijnenlaan 200 E-box 2408, 3001 Leuven (Belgium)
2015-03-01
The applicability of laser ablation multi-collector inductively coupled plasma-mass spectrometry (LA-MC-ICP-MS) for the determination of the B isotopic composition in Roman glasses was investigated. The δ{sup 11}B values thus obtained provide information on the natron flux used during the glass-making process. The glass samples used for this purpose were previously characterized using pneumatic nebulization (PN) MC-ICP-MS. Unfortunately, this method is time-consuming and labor-intensive and consumes some 100 mg of sample, which is a rather high amount for ancient materials. Therefore, the use of the less invasive and faster LA-MC-ICP-MS approach was explored. In this work, the results for 29 Roman glasses and 4 home-made glasses obtained using both techniques were compared to assess the suitability of LA-MC-ICP-MS in this context. The results are in excellent agreement within experimental uncertainty. No difference in overall mass discrimination was observed between the Roman glasses, NIST SRM 610 reference glass and B6 obsidian. The expanded uncertainty of the LA-MC-ICP-MS approach was estimated to be < 2‰, which is similar to that obtained upon sample digestion and PN-MC-ICP-MS measurement. - Highlights: • First use of LA-MC-ICP-MS for B isotopic analysis of ancient glass • Careful validation of LA-MC-ICP-MS approach • Similar precision & accuracy via solution MC-ICP-MS after isolation of B • Enhancement of sample throughput & reduction of sample consumption • Improved conditions for archeometric research on (pre-)Roman glass.
2. Highly efficient high temperature electrolysis
DEFF Research Database (Denmark)
Hauch, Anne; Ebbesen, Sune; Jensen, Søren Højgaard
2008-01-01
High temperature electrolysis of water and steam may provide an efficient, cost effective and environmentally friendly production of H-2 Using electricity produced from sustainable, non-fossil energy sources. To achieve cost competitive electrolysis cells that are both high performing i.e. minimum...... internal resistance of the cell, and long-term stable, it is critical to develop electrode materials that are optimal for steam electrolysis. In this article electrolysis cells for electrolysis of water or steam at temperatures above 200 degrees C for production of H-2 are reviewed. High temperature...... electrolysis is favourable from a thermodynamic point of view, because a part of the required energy can be supplied as thermal heat, and the activation barrier is lowered increasing the H-2 production rate. Only two types of cells operating at high temperature (above 200 degrees C) have been described...
3. High-precision measurement of mercury isotope ratios in sediments using cold-vapor generation multi-collector inductively coupled plasma mass spectrometry
International Nuclear Information System (INIS)
Foucher, Delphine; Hintelmann, Holger
2006-01-01
An on-line Hg reduction technique using stannous chloride as the reductant was applied for accurate and precise mercury isotope ratio determinations by multi-collector (MC)-ICP/MS. Special attention has been paid to ensure optimal conditions (such as acquisition time and mercury concentration) allowing precision measurements good enough to be able to significantly detect the anticipated small differences in Hg isotope ratios in nature. Typically, internal precision was better than 0.002% (1 RSE) on all Hg ratios investigated as long as approximately 20 ng of Hg was measured with a 10-min acquisition time. Introducing higher amounts of mercury (50 ng Hg) improved the internal precision to 205 Tl/ 203 Tl correction coupled to a standard-sample bracketing approach. The large number of data acquired allowed us to validate the consistency of our measurements over a one-year period. On average, the short-term uncertainty determined by repeated runs of NIST SRM 1641d Hg standard during a single day was 202 Hg/ 198 Hg, 202 Hg/ 199 Hg, 202 Hg/ 200 Hg, and 202 Hg/ 201 Hg). The precision fell to 202 Hg/ 198 Hg expressed as δ values (per mil deviations relative to NIST SRM 1641d Hg standard solution) displayed differences from +0.74 to -4.00 permille. The magnitude of the Hg fractionation per amu was constant within one type of sample and did not exceed 1.00 permille. Considering all results (the reproducibility of Hg standard solutions, reference sediment samples, and the examination of natural samples), the analytical error of our δ values for the overall method was within ±0.28 permille (1 SD), which was an order of magnitude lower than the extent of fractionation (4.74 permille) observed in sediments. This study confirmed that analytical techniques have reached a level of long-term precision and accuracy that is sufficiently sensitive to detect even small differences in Hg isotope ratios that occur within one type of samples (e.g., between different sediments) and so
4. High efficiency, long life terrestrial solar panel
Science.gov (United States)
Chao, T.; Khemthong, S.; Ling, R.; Olah, S.
1977-01-01
The design of a high efficiency, long life terrestrial module was completed. It utilized 256 rectangular, high efficiency solar cells to achieve high packing density and electrical output. Tooling for the fabrication of solar cells was in house and evaluation of the cell performance was begun. Based on the power output analysis, the goal of a 13% efficiency module was achievable.
5. High-precision measurements of uranium and thorium isotopic ratios by multi-collector inductively coupled plasma mass spectrometry (MC-ICPMS)
Science.gov (United States)
Wang, Lisheng; Ma, Zhibang; Duan, Wuhui
2015-04-01
Isotopic compositions of U-Th and 230Th dating have been widely used in earth sciences, such as chronology, geochemistry, oceanography and hydrology. In this study, five ages of different carbonate samples were measured using 230Th dating technique with U-Th high-precision isotopic measurements by multi-collector inductively coupled plasma mass spectrometry, in Uranium-series Chronology Laboratory, Institute of Geology and Geophysics, Chinese Academy of Sciences.In this study, the precision and accuracy of uranium isotopic composition were estimated by measuring the uranium ratios of NBS-CRM 112A, NBS-CRM U500 and HU-1. The mean measured ratios, 234U/238U = 52.86 (±0.04) × 10-6 and δ234U = -38.36 (±0.77) × 10-3 for NBS-CRM 112A, 234U/238U = 10.4184 (±0.0001) × 10-3, 236U/238U = 15.43 (±0.01) × 10-4 and 238U/235U = 1.00021 (±0.00002) for NBS-CRM U500, 234U/238U = 54.911 (±0.007) and δ234U = -1.04 (±0.13) × 10-3 for HU-1 (95% confidence levels). The U isotope data for standard reference materials are in excellent agreement with previous studies, further highlighting the reliability and analytical capabilities of our technique. We measured the thorium isotopic ratios of three different thorium standards by MC-ICPMS. The three standards (Th-1, Th-2 and Th-3) were mixed by HU-1 and NBS 232Th standard, with the 230Th/232Th ratios from 10-4 to 10-6. The mean measured atomic ratios, 230Th/232Th = 2.1227 (±0.0024) × 10-6, 2.7246 (±0.0026) × 10-5, and 2.8358 (±0.0007) × 10-4 for Th-1, Th-2 and Th-3 (95% confidence levels), respectively. Using this technique, the following standard samples were dated by MC-ICPMS. Sample RKM-4, collected from Babardos Kendal Hill terrace, was used during the first stage of the Uranium-Series Intercomparison Project (USIP-I). Samples 76001, RKM-5 and RKM-6 were studied during the second stage of the USIP program (USIP-II). Sample 76001 is a laminated flowstone, collected from Sumidero Terejapa, Chiapas, Mexico, and samples
6. Highly Efficient Green-Emitting Phosphors Ba2Y5B5O17 with Low Thermal Quenching Due to Fast Energy Transfer from Ce3+ to Tb3.
Science.gov (United States)
Xiao, Yu; Hao, Zhendong; Zhang, Liangliang; Xiao, Wenge; Wu, Dan; Zhang, Xia; Pan, Guo-Hui; Luo, Yongshi; Zhang, Jiahua
2017-04-17
This paper demonstrates a highly thermally stable and efficient green-emitting Ba 2 Y 5 B 5 O 17 :Ce 3+ , Tb 3+ phosphor prepared by high-temperature solid-state reaction. The phosphor exhibits a blue emission band of Ce 3+ and green emission lines of Tb 3+ upon Ce 3+ excitation in the near-UV spectral region. The effect of Ce 3+ to Tb 3+ energy transfer on blue to green emission color tuning and on luminescence thermal stability is studied in the samples codoped with 1% Ce 3+ and various concentrations (0-40%) of Tb 3+ . The green emission of Tb 3+ upon Ce 3+ excitation at 150 °C can keep, on average, 92% of its intensity at room temperature, with the best one showing no intensity decreasing up to 210 °C for 30% Tb 3+ . Meanwhile, Ce 3+ emission intensity only keeps 42% on average at 150 °C. The high thermal stability of the green emission is attributed to suppression of Ce 3+ thermal de-excitation through fast energy transfer to Tb 3+ , which in the green-emitting excited states is highly thermally stable such that no lifetime shortening is observed with raising temperature to 210 °C. The predominant green emission is observed for Tb 3+ concentration of at least 10% due to efficient energy transfer with the transfer efficiency approaching 100% for 40% Tb 3+ . The internal and external quantum yield of the sample with Tb 3+ concentration of 20% can be as high as 76% and 55%, respectively. The green phosphor, thus, shows attractive performance for near-UV-based white-light-emitting diodes applications.
7. Tailored Materials for High Efficiency CIDI Engines
Energy Technology Data Exchange (ETDEWEB)
Grant, G.J.; Jana, S.
2012-03-30
The overall goal of the project, Tailored Materials for High Efficiency Compression Ignition Direct Injection (CIDI) Engines, is to enable the implementation of new combustion strategies, such as homogeneous charge compression ignition (HCCI), that have the potential to significantly increase the energy efficiency of current diesel engines and decrease fuel consumption and environmental emissions. These strategies, however, are increasing the demands on conventional engine materials, either from increases in peak cylinder pressure (PCP) or from increases in the temperature of operation. The specific objective of this project is to investigate the application of a new material processing technology, friction stir processing (FSP), to improve the thermal and mechanical properties of engine components. The concept is to modify the surfaces of conventional, low-cost engine materials. The project focused primarily on FSP in aluminum materials that are compositional analogs to the typical piston and head alloys seen in small- to mid-sized CIDI engines. Investigations have been primarily of two types over the duration of this project: (1) FSP of a cast hypoeutectic Al-Si-Mg (A356/357) alloy with no introduction of any new components, and (2) FSP of Al-Cu-Ni alloys (Alloy 339) by physically stirring-in various quantities of carbon nanotubes/nanofibers or carbon fibers. Experimental work to date on aluminum systems has shown significant increases in fatigue lifetime and stress-level performance in aluminum-silicon alloys using friction processing alone, but work to demonstrate the addition of carbon nanotubes and fibers into aluminum substrates has shown mixed results due primarily to the difficulty in achieving porosity-free, homogeneous distributions of the particulate. A limited effort to understand the effects of FSP on steel materials was also undertaken during the course of this project. Processed regions were created in high-strength, low-alloyed steels up to 0.5 in
8. Measure Guideline. High Efficiency Natural Gas Furnaces
Energy Technology Data Exchange (ETDEWEB)
Brand, L. [Partnership for Advanced Residential Retrofit (PARR), Des Plaines, IL (United States); Rose, W. [Partnership for Advanced Residential Retrofit (PARR), Des Plaines, IL (United States)
2012-10-01
This measure guideline covers installation of high-efficiency gas furnaces, including: when to install a high-efficiency gas furnace as a retrofit measure; how to identify and address risks; and the steps to be used in the selection and installation process. The guideline is written for Building America practitioners and HVAC contractors and installers. It includes a compilation of information provided by manufacturers, researchers, and the Department of Energy as well as recent research results from the Partnership for Advanced Residential Retrofit (PARR) Building America team.
9. Measure Guideline: High Efficiency Natural Gas Furnaces
Energy Technology Data Exchange (ETDEWEB)
Brand, L.; Rose, W.
2012-10-01
This Measure Guideline covers installation of high-efficiency gas furnaces. Topics covered include when to install a high-efficiency gas furnace as a retrofit measure, how to identify and address risks, and the steps to be used in the selection and installation process. The guideline is written for Building America practitioners and HVAC contractors and installers. It includes a compilation of information provided by manufacturers, researchers, and the Department of Energy as well as recent research results from the Partnership for Advanced Residential Retrofit (PARR) Building America team.
10. Saving energy via high-efficiency fans.
Science.gov (United States)
Heine, Thomas
2016-08-01
Thomas Heine, sales and market manager for EC Upgrades, the retrofit arm of global provider of air movement solutions, ebm-papst A&NZ, discusses the retrofitting of high-efficiency fans to existing HVAC equipment to 'drastically reduce energy consumption'.
11. High efficiency lithium-thionyl chloride cell
Science.gov (United States)
Doddapaneni, N.
1982-08-01
The polarization characteristics and the specific cathode capacity of Teflon bonded carbon electrodes in the Li/SOCl2 system have been evaluated. Doping of electrocatalysts such as cobalt and iron phthalocyanine complexes improved both cell voltage and cell rate capability. High efficiency Li/SOCl2 cells were thus achieved with catalyzed cathodes. The electrochemical reduction of SOCl2 seems to undergo modification at catalyzed cathode. For example, the reduction of SOCl2 at FePc catalyzed cathode involves 2-1/2 e-/mole of SOCl2. Furthermore, the reduction mechanism is simplified and unwanted chemical species are eliminated by the catalyst. Thus a potentially safer high efficiency Li/SOCl2 can be anticipated.
12. High Efficiency Centrifugal Compressor for Rotorcraft Applications
Science.gov (United States)
Medic, Gorazd; Sharma, Om P.; Jongwook, Joo; Hardin, Larry W.; McCormick, Duane C.; Cousins, William T.; Lurie, Elizabeth A.; Shabbir, Aamir; Holley, Brian M.; Van Slooten, Paul R.
2017-01-01
A centrifugal compressor research effort conducted by United Technologies Research Center under NASA Research Announcement NNC08CB03C is documented. The objectives were to identify key technical barriers to advancing the aerodynamic performance of high-efficiency, high work factor, compact centrifugal compressor aft-stages for turboshaft engines; to acquire measurements needed to overcome the technical barriers and inform future designs; to design, fabricate, and test a new research compressor in which to acquire the requisite flow field data. A new High-Efficiency Centrifugal Compressor stage -- splittered impeller, splittered diffuser, 90 degree bend, and exit guide vanes -- with aerodynamically aggressive performance and configuration (compactness) goals were designed, fabricated, and subquently tested at the NASA Glenn Research Center.
13. High-power, high-efficiency FELs
International Nuclear Information System (INIS)
Sessler, A.M.
1989-04-01
High power, high efficiency FELs require tapering, as the particles loose energy, so as to maintain resonance between the electromagnetic wave and the particles. They also require focusing of the particles (usually done with curved pole faces) and focusing of the electromagnetic wave (i.e. optical guiding). In addition, one must avoid transverse beam instabilities (primarily resistive wall) and longitudinal instabilities (i.e sidebands). 18 refs., 7 figs., 3 tabs
14. Critical study of high efficiency deep grinding
OpenAIRE
Johnstone, lain
2002-01-01
The recent years, the aerospace industry in particular has embraced and actively pursued the development of stronger high performance materials, namely nickel based superalloys and hardwearing steels. This has resulted in a need for a more efficient method of machining, and this need was answered with the advent of High Efficiency Deep Grinding (HEDG). This relatively new process using Cubic Boron Nitride (CBN) electroplated grinding wheels has been investigated through experim...
15. Mass-spectrometric mining of Hadean zircons by automated SHRIMP multi-collector and single-collector U/Pb zircon age dating: The first 100,000 grains
Science.gov (United States)
Holden, Peter; Lanc, Peter; Ireland, Trevor R.; Harrison, T. Mark; Foster, John J.; Bruce, Zane
2009-09-01
The identification and retrieval of a large population of ancient zircons (>4 Ga; Hadean) is of utmost priority if models of the early evolution of Earth are to be rigorously tested. We have developed a rapid and accurate U-Pb zircon age determination protocol utilizing a fully automated multi-collector ion microprobe, the ANU SHRIMP II, to screen and date these zircons. Unattended data acquisition relies on the calibration of a digitized sample map to the Sensitive High Resolution Ion MicroProbe (SHRIMP) sample-stage co-ordinate system. High precision positioning of individual grains can be produced through optical image processing of a specified mount location. The focal position of the mount can be optimized through a correlation between secondary-ion steering and the spot position on the target. For the Hadean zircon project, sample mounts are photographed and sample locations (normally grain centers) are determined off-line. The sample is loaded, reference points calibrated, and the target positions are then visited sequentially. In SHRIMP II multiple-collector mode, zircons are initially screened (ca. 5 s data acquisition) through their 204Pb corrected 207Pb/206Pb ratio; suitable candidates are then analyzed in a longer routine to obtain better measurement statistics, U/Pb, and concentration data. In SHRIMP I and SHRIMP RG, we have incorporated the automated analysis protocol to single-collector measurements. These routines have been used to analyze over 100,000 zircons from the Jack Hills quartzite. Of these, ca. 7%, have an age greater than 3.8 Ga, the oldest grain being 4372 +/- 6 Ma (2[sigma]), and this age is part of a group of analyses around 4350 Ma which we interpret as the age when continental crust first began to coalesce in this region. In multi-collector mode, the analytical time taken for a single mount with 400 zircons is approximately 6 h; whereas in single-collector mode, the analytical time is ca. 17 h. With this productivity, we can produce
16. High Efficiency Reversible Fuel Cell Power Converter
DEFF Research Database (Denmark)
Pittini, Riccardo
as well as different dc-ac and dc-dc converter topologies are presented and analyzed. A new ac-dc topology for high efficiency data center applications is proposed and an efficiency characterization based on the fuel cell stack I-V characteristic curve is presented. The second part discusses the main...... converter components. Wide bandgap power semiconductors are introduced due to their superior performance in comparison to traditional silicon power devices. The analysis presents a study based on switching loss measurements performed on Si IGBTs, SiC JFETs, SiC MOSFETs and their respective gate drivers...
17. High efficiency inverter and ballast circuits
International Nuclear Information System (INIS)
Nilssen, O.K.
1984-01-01
A high efficiency push-pull inverter circuit employing a pair of relatively high power switching transistors is described. The switching on and off of the transistors is precisely controlled to minimize power losses due to common-mode conduction or due to transient conditions that occur in the process of turning a transistor on or off. Two current feed-back transformers are employed in the transistor base drives; one being saturable for providing a positive feedback, and the other being non-saturable for providing a subtractive feedback
18. CFD application to advanced design for high efficiency spacer grid
Energy Technology Data Exchange (ETDEWEB)
Ikeda, Kazuo, E-mail: kazuo3_ikeda@ndc.mhi.co.jp
2014-11-15
Highlights: • A new LDV was developed to investigate the local velocity in a rod bundle and inside a spacer grid. • The design information that utilizes for high efficiency spacer grid has been obtained. • CFD methodology that predicts flow field in a PWR fuel has been developed. • The high efficiency spacer grid was designed using the CFD methodology. - Abstract: Pressurized water reactor (PWR) fuels have been developed to meet the needs of the market. A spacer grid is a key component to improve thermal hydraulic performance of a PWR fuel assembly. Mixing structures (vanes) of a spacer grid promote coolant mixing and enhance heat removal from fuel rods. A larger mixing vane would improve mixing effect, which would increase the departure from nucleate boiling (DNB) benefit for fuel. However, the increased pressure loss at large mixing vanes would reduce the coolant flow at the mixed fuel core, which would reduce the DNB margin. The solution is to develop a spacer grid whose pressure loss is equal to or less than the current spacer grid and that has higher critical heat flux (CHF) performance. For this reason, a requirement of design tool for predicting the pressure loss and CHF performance of spacer grids has been increased. The author and co-workers have been worked for development of high efficiency spacer grid using Computational Fluid Dynamics (CFD) for nearly 20 years. A new laser Doppler velocimetry (LDV), which is miniaturized with fiber optics embedded in a fuel cladding, was developed to investigate the local velocity profile in a rod bundle and inside a spacer grid. The rod-embedded fiber LDV (rod LDV) can be inserted in an arbitrary grid cell instead of a fuel rod, and has the advantage of not disturbing the flow field since it is the same shape as a fuel rod. The probe volume of the rod LDV is small enough to measure spatial velocity profile in a rod gap and inside a spacer grid. According to benchmark experiments such as flow velocity
19. CFD application to advanced design for high efficiency spacer grid
International Nuclear Information System (INIS)
Ikeda, Kazuo
2014-01-01
Highlights: • A new LDV was developed to investigate the local velocity in a rod bundle and inside a spacer grid. • The design information that utilizes for high efficiency spacer grid has been obtained. • CFD methodology that predicts flow field in a PWR fuel has been developed. • The high efficiency spacer grid was designed using the CFD methodology. - Abstract: Pressurized water reactor (PWR) fuels have been developed to meet the needs of the market. A spacer grid is a key component to improve thermal hydraulic performance of a PWR fuel assembly. Mixing structures (vanes) of a spacer grid promote coolant mixing and enhance heat removal from fuel rods. A larger mixing vane would improve mixing effect, which would increase the departure from nucleate boiling (DNB) benefit for fuel. However, the increased pressure loss at large mixing vanes would reduce the coolant flow at the mixed fuel core, which would reduce the DNB margin. The solution is to develop a spacer grid whose pressure loss is equal to or less than the current spacer grid and that has higher critical heat flux (CHF) performance. For this reason, a requirement of design tool for predicting the pressure loss and CHF performance of spacer grids has been increased. The author and co-workers have been worked for development of high efficiency spacer grid using Computational Fluid Dynamics (CFD) for nearly 20 years. A new laser Doppler velocimetry (LDV), which is miniaturized with fiber optics embedded in a fuel cladding, was developed to investigate the local velocity profile in a rod bundle and inside a spacer grid. The rod-embedded fiber LDV (rod LDV) can be inserted in an arbitrary grid cell instead of a fuel rod, and has the advantage of not disturbing the flow field since it is the same shape as a fuel rod. The probe volume of the rod LDV is small enough to measure spatial velocity profile in a rod gap and inside a spacer grid. According to benchmark experiments such as flow velocity
20. High efficiency and broadband acoustic diodes
Science.gov (United States)
Fu, Congyi; Wang, Bohan; Zhao, Tianfei; Chen, C. Q.
2018-01-01
Energy transmission efficiency and working bandwidth are the two major factors limiting the application of current acoustic diodes (ADs). This letter presents a design of high efficiency and broadband acoustic diodes composed of a nonlinear frequency converter and a linear wave filter. The converter consists of two masses connected by a bilinear spring with asymmetric tension and compression stiffness. The wave filter is a linear mass-spring lattice (sonic crystal). Both numerical simulation and experiment show that the energy transmission efficiency of the acoustic diode can be improved by as much as two orders of magnitude, reaching about 61%. Moreover, the primary working band width of the AD is about two times of the cut-off frequency of the sonic crystal filter. The cut-off frequency dependent working band of the AD implies that the developed AD can be scaled up or down from macro-scale to micro- and nano-scale.
1. Experiments on high efficiency aerosol filtration
International Nuclear Information System (INIS)
Mazzini, M.; Cuccuru, A.; Kunz, P.
1977-01-01
Research on high efficiency aerosol filtration by the Nuclear Engineering Institute of Pisa University and by CAMEN in collaboration with CNEN is outlined. HEPA filter efficiency was studied as a function of the type and size of the test aerosol, and as a function of flowrate (+-50% of the nominal value), air temperature (up to 70 0 C), relative humidity (up to 100%), and durability in a corrosive atmosphere (up to 140 hours in NaCl mist). In the selected experimental conditions these influences were appreciable but are not sufficient to be significant in industrial HEPA filter applications. Planned future research is outlined: measurement of the efficiency of two HEPA filters in series using a fixed particle size; dependence of the efficiency on air, temperatures up to 300-500 0 C; performance when subject to smoke from burning organic materials (natural rubber, neoprene, miscellaneous plastics). Such studies are relevant to possible accidental fires in a plutonium laboratory
2. High efficiency motors; Motores de alta eficiencia
Energy Technology Data Exchange (ETDEWEB)
Uranga Favela, Ivan Jaime [Energia Controlada de Mexico, S. A. de C. V., Mexico, D. F. (Mexico)
1993-12-31
This paper is a technical-financial study of the high efficiency and super-premium motors. As it is widely known, more than 60% of the electrical energy generated in the country is used for the operation of motors, in industry as well as in commerce. Therefore the importance that the motors have in the efficient energy use. [Espanol] El presente trabajo es un estudio tecnico-financiero de los motores de alta eficiencia y los motores super premium. Como es ampliamente conocido, mas del 60% de la energia electrica generada en el pais, es utilizada para accionar motores, dentro de la industria y el comercio. De alli la importancia que los motores tienen en el uso eficiente de la energia.
3. High efficiency thin-film solar cells
Energy Technology Data Exchange (ETDEWEB)
Schock, Hans-Werner [Helmholtz Zentrum Berlin (Germany). Solar Energy
2012-11-01
Production of photovoltaics is growing worldwide on a gigawatt scale. Among the thin film technologies, Cu(In,Ga)S,Se{sub 2} (CIS or CIGS) based solar cells have been the focus of more and more attention. This paper aims to analyze the success of CIGS based solar cells and the potential of this technology for future photovoltaics large-scale production. Specific material properties make CIS unique and allow the preparation of the material with a wide range of processing options. The huge potential lies in the possibility to take advantage of modern thin film processing equipment and combine it with very high efficiencies beyond 20% already achieved on the laboratory scale. A sustainable development of this technology could be realized by modifying the materials and replacing indium by abundant elements. (orig.)
4. Complexity-aware high efficiency video coding
CERN Document Server
Correa, Guilherme; Agostini, Luciano; Cruz, Luis A da Silva
2016-01-01
This book discusses computational complexity of High Efficiency Video Coding (HEVC) encoders with coverage extending from the analysis of HEVC compression efficiency and computational complexity to the reduction and scaling of its encoding complexity. After an introduction to the topic and a review of the state-of-the-art research in the field, the authors provide a detailed analysis of the HEVC encoding tools compression efficiency and computational complexity. Readers will benefit from a set of algorithms for scaling the computational complexity of HEVC encoders, all of which take advantage from the flexibility of the frame partitioning structures allowed by the standard. The authors also provide a set of early termination methods based on data mining and machine learning techniques, which are able to reduce the computational complexity required to find the best frame partitioning structures. The applicability of the proposed methods is finally exemplified with an encoding time control system that emplo...
5. Design of High Efficient MPPT Solar Inverter
Directory of Open Access Journals (Sweden)
Sunitha K. A.
2017-01-01
Full Text Available This work aims to design a High Efficient Maximum Power Point Tracking (MPPT Solar Inverter. A boost converter is designed in the system to boost the power from the photovoltaic panel. By this experimental setup a room consisting of 500 Watts load (eight fluorescent tubes is completely controlled. It is aimed to decrease the maintenance cost. A microcontroller is introduced for tracking the P&O (Perturb and Observe algorithm used for tracking the maximum power point. The duty cycle for the operation of the boost convertor is optimally adjusted by using MPPT controller. There is a MPPT charge controller to charge the battery as well as fed to inverter which runs the load. Both the P&O scheme with the fixed variation for the reference current and the intelligent MPPT algorithm were able to identify the global Maximum power point, however the performance of the MPPT algorithm was better.
6. High Efficiency Ka-Band Spatial Combiner
Directory of Open Access Journals (Sweden)
D. Passi
2014-12-01
Full Text Available A Ka-Band, High Efficiency, Small Size Spatial Combiner (SPC is proposed in this paper, which uses an innovatively matched quadruple Fin Lines to microstrip (FLuS transitions. At the date of this paper and at the Author's best knowledge no such FLuS innovative transitions have been reported in literature before. These transitions are inserted into a WR28 waveguide T-junction, in order to allow the integration of 16 Monolithic Microwave Integrated Circuit (MMIC Solid State Power Amplifiers (SSPA's. A computational electromagnetic model using the finite elements method has been implemented. A mean insertion loss of 2 dB is achieved with a return loss better the 10 dB in the 31-37 GHz bandwidth.
7. High efficiency motors; Motores de alta eficiencia
Energy Technology Data Exchange (ETDEWEB)
Uranga Favela, Ivan Jaime [Energia Controlada de Mexico, S. A. de C. V., Mexico, D. F. (Mexico)
1992-12-31
This paper is a technical-financial study of the high efficiency and super-premium motors. As it is widely known, more than 60% of the electrical energy generated in the country is used for the operation of motors, in industry as well as in commerce. Therefore the importance that the motors have in the efficient energy use. [Espanol] El presente trabajo es un estudio tecnico-financiero de los motores de alta eficiencia y los motores super premium. Como es ampliamente conocido, mas del 60% de la energia electrica generada en el pais, es utilizada para accionar motores, dentro de la industria y el comercio. De alli la importancia que los motores tienen en el uso eficiente de la energia.
8. Multi-petascale highly efficient parallel supercomputer
Science.gov (United States)
Asaad, Sameh; Bellofatto, Ralph E.; Blocksome, Michael A.; Blumrich, Matthias A.; Boyle, Peter; Brunheroto, Jose R.; Chen, Dong; Cher, Chen-Yong; Chiu, George L.; Christ, Norman; Coteus, Paul W.; Davis, Kristan D.; Dozsa, Gabor J.; Eichenberger, Alexandre E.; Eisley, Noel A.; Ellavsky, Matthew R.; Evans, Kahn C.; Fleischer, Bruce M.; Fox, Thomas W.; Gara, Alan; Giampapa, Mark E.; Gooding, Thomas M.; Gschwind, Michael K.; Gunnels, John A.; Hall, Shawn A.; Haring, Rudolf A.; Heidelberger, Philip; Inglett, Todd A.; Knudson, Brant L.; Kopcsay, Gerard V.; Kumar, Sameer; Mamidala, Amith R.; Marcella, James A.; Megerian, Mark G.; Miller, Douglas R.; Miller, Samuel J.; Muff, Adam J.; Mundy, Michael B.; O'Brien, John K.; O'Brien, Kathryn M.; Ohmacht, Martin; Parker, Jeffrey J.; Poole, Ruth J.; Ratterman, Joseph D.; Salapura, Valentina; Satterfield, David L.; Senger, Robert M.; Steinmacher-Burow, Burkhard; Stockdell, William M.; Stunkel, Craig B.; Sugavanam, Krishnan; Sugawara, Yutaka; Takken, Todd E.; Trager, Barry M.; Van Oosten, James L.; Wait, Charles D.; Walkup, Robert E.; Watson, Alfred T.; Wisniewski, Robert W.; Wu, Peng
2018-05-15
A Multi-Petascale Highly Efficient Parallel Supercomputer of 100 petaflop-scale includes node architectures based upon System-On-a-Chip technology, where each processing node comprises a single Application Specific Integrated Circuit (ASIC). The ASIC nodes are interconnected by a five dimensional torus network that optimally maximize the throughput of packet communications between nodes and minimize latency. The network implements collective network and a global asynchronous network that provides global barrier and notification functions. Integrated in the node design include a list-based prefetcher. The memory system implements transaction memory, thread level speculation, and multiversioning cache that improves soft error rate at the same time and supports DMA functionality allowing for parallel processing message-passing.
9. High efficiency beam splitting for H- accelerators
International Nuclear Information System (INIS)
Kramer, S.L.; Stipp, V.; Krieger, C.; Madsen, J.
1985-01-01
Beam splitting for high energy accelerators has typically involved a significant loss of beam and radiation. This paper reports on a new method of splitting beams for H - accelerators. This technique uses a high intensity flash of light to strip a fraction of the H - beam to H 0 which are then easily separated by a small bending magnet. A system using a 900-watt (average electrical power) flashlamp and a highly efficient collector will provide 10 -3 to 10 -2 splitting of a 50 MeV H - beam. Results on the operation and comparisons with stripping cross sections are presented. Also discussed is the possibility for developing this system to yield a higher stripping fraction
10. The CRRES high efficiency solar panel
International Nuclear Information System (INIS)
Trumble, T.M.
1991-01-01
This paper reports on the High Efficiency Solar Panel (HESP) experiments which is to provide both engineering and scientific information concerning the effects of space radiation on advanced gallium arsenide (GaAs) solar cells. The HESP experiment consists of an ambient panel, and annealing panel and a programmable load. This experiment, in conjunction with the radiation measurement experiments abroad the CREES, provides the first opportunity to simultaneously measure the trapped radiation belts and the results of radiation damage to solar cells. The engineering information will result in a design guide for selecting the optimum solar array characteristics for different orbits and different lifetimes. The scientific information will provide both correlation of laboratory damage effects to space damage effects and a better model for predicting effective solar cell panel lifetimes
11. High Efficiency, Low Emission Refrigeration System
Energy Technology Data Exchange (ETDEWEB)
Fricke, Brian A [ORNL; Sharma, Vishaldeep [ORNL
2016-08-01
Supermarket refrigeration systems account for approximately 50% of supermarket energy use, placing this class of equipment among the highest energy consumers in the commercial building domain. In addition, the commonly used refrigeration system in supermarket applications is the multiplex direct expansion (DX) system, which is prone to refrigerant leaks due to its long lengths of refrigerant piping. This leakage reduces the efficiency of the system and increases the impact of the system on the environment. The high Global Warming Potential (GWP) of the hydrofluorocarbon (HFC) refrigerants commonly used in these systems, coupled with the large refrigerant charge and the high refrigerant leakage rates leads to significant direct emissions of greenhouse gases into the atmosphere. Methods for reducing refrigerant leakage and energy consumption are available, but underutilized. Further work needs to be done to reduce costs of advanced system designs to improve market utilization. In addition, refrigeration system retrofits that result in reduced energy consumption are needed since the majority of applications address retrofits rather than new stores. The retrofit market is also of most concern since it involves large-volume refrigerant systems with high leak rates. Finally, alternative refrigerants for new and retrofit applications are needed to reduce emissions and reduce the impact on the environment. The objective of this Collaborative Research and Development Agreement (CRADA) between the Oak Ridge National Laboratory and Hill Phoenix is to develop a supermarket refrigeration system that reduces greenhouse gas emissions and has 25 to 30 percent lower energy consumption than existing systems. The outcomes of this project will include the design of a low emission, high efficiency commercial refrigeration system suitable for use in current U.S. supermarkets. In addition, a prototype low emission, high efficiency supermarket refrigeration system will be produced for
12. High-Temperature High-Efficiency Solar Thermoelectric Generators
Energy Technology Data Exchange (ETDEWEB)
Baranowski, LL; Warren, EL; Toberer, ES
2014-03-01
Inspired by recent high-efficiency thermoelectric modules, we consider thermoelectrics for terrestrial applications in concentrated solar thermoelectric generators (STEGs). The STEG is modeled as two subsystems: a TEG, and a solar absorber that efficiently captures the concentrated sunlight and limits radiative losses from the system. The TEG subsystem is modeled using thermoelectric compatibility theory; this model does not constrain the material properties to be constant with temperature. Considering a three-stage TEG based on current record modules, this model suggests that 18% efficiency could be experimentally expected with a temperature gradient of 1000A degrees C to 100A degrees C. Achieving 15% overall STEG efficiency thus requires an absorber efficiency above 85%, and we consider two methods to achieve this: solar-selective absorbers and thermally insulating cavities. When the TEG and absorber subsystem models are combined, we expect that the STEG modeled here could achieve 15% efficiency with optical concentration between 250 and 300 suns.
13. High efficiency graphene coated copper based thermocells connected in series
Science.gov (United States)
Sindhuja, Mani; Indubala, Emayavaramban; Sudha, Venkatachalam; Harinipriya, Seshadri
2018-04-01
Conversion of low-grade waste heat into electricity had been studied employing single thermocell or flowcells so far. Graphene coated copper electrodes based thermocells connected in series displayed relatively high efficiency of thermal energy harvesting. The maximum power output of 49.2W/m2 for normalized cross sectional electrode area is obtained at 60ºC of inter electrode temperature difference. The relative carnot efficiency of 20.2% is obtained from the device. The importance of reducing the mass transfer and ion transfer resistance to improve the efficiency of the device is demonstrated. Degradation studies confirmed mild oxidation of copper foil due to corrosion caused by the electrolyte.
14. High Efficiency Graphene Coated Copper Based Thermocells Connected in Series
Directory of Open Access Journals (Sweden)
Mani Sindhuja
2018-04-01
Full Text Available Conversion of low-grade waste heat into electricity had been studied employing single thermocell or flowcells so far. Graphene coated copper electrodes based thermocells connected in series displayed relatively high efficiency of thermal energy harvesting. The maximum power output of 49.2 W/m2 for normalized cross sectional electrode area is obtained at 60°C of inter electrode temperature difference. The relative carnot efficiency of 20.2% is obtained from the device. The importance of reducing the mass transfer and ion transfer resistance to improve the efficiency of the device is demonstrated. Degradation studies confirmed mild oxidation of copper foil due to corrosion caused by the electrolyte.
15. Bioblendstocks that Enable High Efficiency Engine Designs
Energy Technology Data Exchange (ETDEWEB)
McCormick, Robert L.; Fioroni, Gina M.; Ratcliff, Matthew A.; Zigler, Bradley T.; Farrell, John
2016-11-03
The past decade has seen a high level of innovation in production of biofuels from sugar, lipid, and lignocellulose feedstocks. As discussed in several talks at this workshop, ethanol blends in the E25 to E50 range could enable more highly efficient spark-ignited (SI) engines. This is because of their knock resistance properties that include not only high research octane number (RON), but also charge cooling from high heat of vaporization, and high flame speed. Emerging alcohol fuels such as isobutanol or mixed alcohols have desirable properties such as reduced gasoline blend vapor pressure, but also have lower RON than ethanol. These fuels may be able to achieve the same knock resistance benefits, but likely will require higher blend levels or higher RON hydrocarbon blendstocks. A group of very high RON (>150) oxygenates such as dimethyl furan, methyl anisole, and related compounds are also produced from biomass. While providing no increase in charge cooling, their very high octane numbers may provide adequate knock resistance for future highly efficient SI engines. Given this range of options for highly knock resistant fuels there appears to be a critical need for a fuel knock resistance metric that includes effects of octane number, heat of vaporization, and potentially flame speed. Emerging diesel fuels include highly branched long-chain alkanes from hydroprocessing of fats and oils, as well as sugar-derived terpenoids. These have relatively high cetane number (CN), which may have some benefits in designing more efficient CI engines. Fast pyrolysis of biomass can produce diesel boiling range streams that are high in aromatic, oxygen and acid contents. Hydroprocessing can be applied to remove oxygen and consequently reduce acidity, however there are strong economic incentives to leave up to 2 wt% oxygen in the product. This oxygen will primarily be present as low CN alkyl phenols and aryl ethers. While these have high heating value, their presence in diesel fuel
16. High efficiency novel window air conditioner
International Nuclear Information System (INIS)
2015-01-01
Highlights: • Use of novel refrigerant mixture of R32/R125 (85/15% molar conc.) to reduce global warming and improve energy efficiency. • Use of novel features such as electronically commuted motor (ECM) fan motor, slinger and sub-merged sub-cooler. • Energy savings of up to 0.1 Quads per year in USA and much more in Asia/Middle East where WACs are used in large numbers. • Payback period of only 1.4 years of the novel efficient WAC. - Abstract: This paper presents the results of an experimental and analytical evaluation of measures to raise the efficiency of window air conditioners (WAC). In order to achieve a higher energy efficiency ratio (EER), the original capacity of a baseline R410A unit was reduced by replacing the original compressor with a lower capacity but higher EER compressor, while all heat exchangers and the chassis from the original unit were retained. Subsequent major modifications included – replacing the alternating current fan motor with a brushless high efficiency electronically commutated motor (ECM) motor, replacing the capillary tube with a needle valve to better control the refrigerant flow and refrigerant set points, and replacing R410A with a ‘drop-in’ lower global warming potential (GWP) binary mixture of R32/R125 (85/15% molar concentration). All these modifications resulted in significant enhancement in the EER of the baseline WAC. Further, an economic analysis of the new WAC revealed an encouraging payback period
17. High efficiency diffusion molecular retention tumor targeting.
Directory of Open Access Journals (Sweden)
Yanyan Guo
Full Text Available Here we introduce diffusion molecular retention (DMR tumor targeting, a technique that employs PEG-fluorochrome shielded probes that, after a peritumoral (PT injection, undergo slow vascular uptake and extensive interstitial diffusion, with tumor retention only through integrin molecular recognition. To demonstrate DMR, RGD (integrin binding and RAD (control probes were synthesized bearing DOTA (for (111 In(3+, a NIR fluorochrome, and 5 kDa PEG that endows probes with a protein-like volume of 25 kDa and decreases non-specific interactions. With a GFP-BT-20 breast carcinoma model, tumor targeting by the DMR or i.v. methods was assessed by surface fluorescence, biodistribution of [(111In] RGD and [(111In] RAD probes, and whole animal SPECT. After a PT injection, both probes rapidly diffused through the normal and tumor interstitium, with retention of the RGD probe due to integrin interactions. With PT injection and the [(111In] RGD probe, SPECT indicated a highly tumor specific uptake at 24 h post injection, with 352%ID/g tumor obtained by DMR (vs 4.14%ID/g by i.v.. The high efficiency molecular targeting of DMR employed low probe doses (e.g. 25 ng as RGD peptide, which minimizes toxicity risks and facilitates clinical translation. DMR applications include the delivery of fluorochromes for intraoperative tumor margin delineation, the delivery of radioisotopes (e.g. toxic, short range alpha emitters for radiotherapy, or the delivery of photosensitizers to tumors accessible to light.
18. High-efficiency concentrator silicon solar cells
Energy Technology Data Exchange (ETDEWEB)
Sinton, R.A.; Cuevas, A.; King, R.R.; Swanson, R.M. (Stanford Univ., CA (USA). Solid-State Electronics Lab.)
1990-11-01
This report presents results from extensive process development in high-efficiency Si solar cells. An advanced design for a 1.56-cm{sup 2} cell with front grids achieved 26% efficiency at 90 suns. This is especially significant since this cell does not require a prismatic cover glass. New designs for simplified backside-contact solar cells were advanced from a status of near-nonfunctionality to demonstrated 21--22% for one-sun cells in sizes up to 37.5 cm{sup 2}. An efficiency of 26% was achieved for similar 0.64-cm{sup 2} concentrator cells at 150 suns. More fundamental work on dopant-diffused regions is also presented here. The recombination vs. various process and physical parameters was studied in detail for boron and phosphorous diffusions. Emitter-design studies based solidly upon these new data indicate the performance vs design parameters for a variety of the cases of most interest to solar cell designers. Extractions of p-type bandgap narrowing and the surface recombination for p- and n-type regions from these studies have a generality that extends beyond solar cells into basic device modeling. 68 refs., 50 figs.
19. High efficiency, variable geometry, centrifugal cryogenic pump
International Nuclear Information System (INIS)
Forsha, M.D.; Nichols, K.E.; Beale, C.A.
1994-01-01
20. Multi-petascale highly efficient parallel supercomputer
Science.gov (United States)
Asaad, Sameh; Bellofatto, Ralph E.; Blocksome, Michael A.; Blumrich, Matthias A.; Boyle, Peter; Brunheroto, Jose R.; Chen, Dong; Cher, Chen -Yong; Chiu, George L.; Christ, Norman; Coteus, Paul W.; Davis, Kristan D.; Dozsa, Gabor J.; Eichenberger, Alexandre E.; Eisley, Noel A.; Ellavsky, Matthew R.; Evans, Kahn C.; Fleischer, Bruce M.; Fox, Thomas W.; Gara, Alan; Giampapa, Mark E.; Gooding, Thomas M.; Gschwind, Michael K.; Gunnels, John A.; Hall, Shawn A.; Haring, Rudolf A.; Heidelberger, Philip; Inglett, Todd A.; Knudson, Brant L.; Kopcsay, Gerard V.; Kumar, Sameer; Mamidala, Amith R.; Marcella, James A.; Megerian, Mark G.; Miller, Douglas R.; Miller, Samuel J.; Muff, Adam J.; Mundy, Michael B.; O'Brien, John K.; O'Brien, Kathryn M.; Ohmacht, Martin; Parker, Jeffrey J.; Poole, Ruth J.; Ratterman, Joseph D.; Salapura, Valentina; Satterfield, David L.; Senger, Robert M.; Smith, Brian; Steinmacher-Burow, Burkhard; Stockdell, William M.; Stunkel, Craig B.; Sugavanam, Krishnan; Sugawara, Yutaka; Takken, Todd E.; Trager, Barry M.; Van Oosten, James L.; Wait, Charles D.; Walkup, Robert E.; Watson, Alfred T.; Wisniewski, Robert W.; Wu, Peng
2015-07-14
A Multi-Petascale Highly Efficient Parallel Supercomputer of 100 petaOPS-scale computing, at decreased cost, power and footprint, and that allows for a maximum packaging density of processing nodes from an interconnect point of view. The Supercomputer exploits technological advances in VLSI that enables a computing model where many processors can be integrated into a single Application Specific Integrated Circuit (ASIC). Each ASIC computing node comprises a system-on-chip ASIC utilizing four or more processors integrated into one die, with each having full access to all system resources and enabling adaptive partitioning of the processors to functions such as compute or messaging I/O on an application by application basis, and preferably, enable adaptive partitioning of functions in accordance with various algorithmic phases within an application, or if I/O or other processors are underutilized, then can participate in computation or communication nodes are interconnected by a five dimensional torus network with DMA that optimally maximize the throughput of packet communications between nodes and minimize latency.
1. The thermodynamic characteristics of high efficiency, internal-combustion engines
International Nuclear Information System (INIS)
Caton, Jerald A.
2012-01-01
Highlights: ► The thermodynamics of an automotive engine are determined using a cycle simulation. ► The net indicated thermal efficiency increased from 37.0% to 53.9%. ► High compression ratio, lean mixtures and high EGR were the important features. ► Efficiency increased due to lower heat losses, and increased work conversion. ► The nitric oxides were essentially zero due to the low combustion temperatures. - Abstract: Recent advancements have demonstrated new combustion modes for internal combustion engines that exhibit low nitric oxide emissions and high thermal efficiencies. These new combustion modes involve various combinations of stratification, lean mixtures, high levels of EGR, multiple injections, variable valve timings, two fuels, and other such features. Although the exact combination of these features that provides the best design is not yet clear, the results (low emissions with high efficiencies) are of major interest. The current work is directed at determining some of the fundamental thermodynamic reasons for the relatively high efficiencies and to quantify these factors. Both the first and second laws are used in this assessment. An automotive engine (5.7 l) which included some of the features mentioned above (e.g., high compression ratios, lean mixtures, and high EGR) was evaluated using a thermodynamic cycle simulation. These features were examined for a moderate load (bmep = 900 kPa), moderate speed (2000 rpm) condition. By the use of lean operation, high EGR levels, high compression ratio and other features, the net indicated thermal efficiency increased from 37.0% to 53.9%. These increases are explained in a step-by-step fashion. The major reasons for these improvements include the higher compression ratio and the dilute charge (lean mixture, high EGR). The dilute charge resulted in lower temperatures which in turn resulted in lower heat loss. In addition, the lower temperatures resulted in higher ratios of the specific heats which
2. Fusion blankets for high efficiency power cycles
International Nuclear Information System (INIS)
Powell, J.R.; Fillo, J.A.; Horn, F.L.; Lazareth, O.W.; Usher, J.L.
1980-04-01
Definitions are given of 10 generic blanket types and the specific blanket chosen to be analyzed in detail from each of the 10 types. Dimensions, compositions, energy depositions and breeding ratios (where applicable) are presented for each of the 10 designs. Ultimately, based largely on neutronics and thermal hyraulics results, breeding an nonbreeding blanket options are selected for further design analysis and integration with a suitable power conversion subsystem
3. High efficiency double sided solar cells
International Nuclear Information System (INIS)
Seddik, M.M.
1990-06-01
Silicon technology state of the art for single crystalline was given to be limited to less than 20% efficiency. A proposed new form of photovoltaic solar cell of high current high efficiency with double sided structures has been given. The new forms could be n ++ pn ++ or p ++ np ++ double side junctions. The idea of double sided devices could be understood as two solar cells connected back-to-back in parallel electrical connection, in which the current is doubled if the cell is illuminated from both sides by a V-shaped reflector. The cell is mounted to the reflector such that each face is inclined at an angle of 45 deg. C to each side of the reflector. The advantages of the new structure are: a) High power devices. b) Easy to fabricate. c) The cells are used vertically instead of horizontal use of regular solar cell which require large area to install. This is very important in power stations and especially for satellite installation. If the proposal is made real and proved to be experimentally feasible, it would be a new era for photovoltaic solar cells since the proposal has already been extended to even higher currents. The suggested structures could be stated as: n ++ pn ++ Vp ++ np ++ ;n ++ pn ++ Vn ++ pn ++ ORp ++ np ++ Vp ++ np ++ . These types of structures are formed in wedged shape to employ indirect illumination by either parabolic; conic or V-shaped reflectors. The advantages of these new forms are low cost; high power; less in size and space; self concentrating; ... etc. These proposals if it happens to find their ways to be achieved experimentally, I think they will offer a short path to commercial market and would have an incredible impact on solar cell technology and applications. (author). 12 refs, 5 figs
4. Multiscale approaches to high efficiency photovoltaics
Directory of Open Access Journals (Sweden)
Connolly James Patrick
2016-01-01
Full Text Available While renewable energies are achieving parity around the globe, efforts to reach higher solar cell efficiencies becomes ever more difficult as they approach the limiting efficiency. The so-called third generation concepts attempt to break this limit through a combination of novel physical processes and new materials and concepts in organic and inorganic systems. Some examples of semi-empirical modelling in the field are reviewed, in particular for multispectral solar cells on silicon (French ANR project MultiSolSi. Their achievements are outlined, and the limits of these approaches shown. This introduces the main topic of this contribution, which is the use of multiscale experimental and theoretical techniques to go beyond the semi-empirical understanding of these systems. This approach has already led to great advances at modelling which have led to modelling software, which is widely known. Yet, a survey of the topic reveals a fragmentation of efforts across disciplines, firstly, such as organic and inorganic fields, but also between the high efficiency concepts such as hot carrier cells and intermediate band concepts. We show how this obstacle to the resolution of practical research obstacles may be lifted by inter-disciplinary cooperation across length scales, and across experimental and theoretical fields, and finally across materials systems. We present a European COST Action “MultiscaleSolar” kicking off in early 2015, which brings together experimental and theoretical partners in order to develop multiscale research in organic and inorganic materials. The goal of this defragmentation and interdisciplinary collaboration is to develop understanding across length scales, which will enable the full potential of third generation concepts to be evaluated in practise, for societal and industrial applications.
5. Radiation hardened high efficiency silicon space solar cell
International Nuclear Information System (INIS)
Garboushian, V.; Yoon, S.; Turner, J.
1993-01-01
A silicon solar cell with AMO 19% Beginning of Life (BOL) efficiency is reported. The cell has demonstrated equal or better radiation resistance when compared to conventional silicon space solar cells. Conventional silicon space solar cell performance is generally ∼ 14% at BOL. The Radiation Hardened High Efficiency Silicon (RHHES) cell is thinned for high specific power (watts/kilogram). The RHHES space cell provides compatibility with automatic surface mounting technology. The cells can be easily combined to provide desired power levels and voltages. The RHHES space cell is more resistant to mechanical damage due to micrometeorites. Micro-meteorites which impinge upon conventional cells can crack the cell which, in turn, may cause string failure. The RHHES, operating in the same environment, can continue to function with a similar crack. The RHHES cell allows for very efficient thermal management which is essential for space cells generating higher specific power levels. The cell eliminates the need for electrical insulation layers which would otherwise increase the thermal resistance for conventional space panels. The RHHES cell can be applied to a space concentrator panel system without abandoning any of the attributes discussed. The power handling capability of the RHHES cell is approximately five times more than conventional space concentrator solar cells
6. Recent Advances in High Efficiency Solar Cells
Institute of Scientific and Technical Information of China (English)
Yoshio; Ohshita; Hidetoshi; Suzuki; Kenichi; Nishimura; Masafumi; Yamaguchi
2007-01-01
1 Results The conversion efficiency of sunlight to electricity is limited around 25%,when we use single junction solar cells. In the single junction cells,the major energy losses arise from the spectrum mismatching. When the photons excite carriers with energy well in excess of the bandgap,these excess energies were converted to heat by the rapid thermalization. On the other hand,the light with lower energy than that of the bandgap cannot be absorbed by the semiconductor,resulting in the losses. One way...
7. Evaluating performance of high efficiency mist eliminators
Energy Technology Data Exchange (ETDEWEB)
Waggoner, Charles A.; Parsons, Michael S.; Giffin, Paxton K. [Mississippi State University, Institute for Clean Energy Technology, 205 Research Blvd, Starkville, MS (United States)
2013-07-01
Processing liquid wastes frequently generates off gas streams with high humidity and liquid aerosols. Droplet laden air streams can be produced from tank mixing or sparging and processes such as reforming or evaporative volume reduction. Unfortunately these wet air streams represent a genuine threat to HEPA filters. High efficiency mist eliminators (HEME) are one option for removal of liquid aerosols with high dissolved or suspended solids content. HEMEs have been used extensively in industrial applications, however they have not seen widespread use in the nuclear industry. Filtering efficiency data along with loading curves are not readily available for these units and data that exist are not easily translated to operational parameters in liquid waste treatment plants. A specialized test stand has been developed to evaluate the performance of HEME elements under use conditions of a US DOE facility. HEME elements were tested at three volumetric flow rates using aerosols produced from an iron-rich waste surrogate. The challenge aerosol included submicron particles produced from Laskin nozzles and super micron particles produced from a hollow cone spray nozzle. Test conditions included ambient temperature and relative humidities greater than 95%. Data collected during testing HEME elements from three different manufacturers included volumetric flow rate, differential temperature across the filter housing, downstream relative humidity, and differential pressure (dP) across the filter element. Filter challenge was discontinued at three intermediate dPs and the filter to allow determining filter efficiency using dioctyl phthalate and then with dry surrogate aerosols. Filtering efficiencies of the clean HEME, the clean HEME loaded with water, and the HEME at maximum dP were also collected using the two test aerosols. Results of the testing included differential pressure vs. time loading curves for the nine elements tested along with the mass of moisture and solid
8. Highly Efficient Thermostable DSM Cellulases: Why & How?
Energy Technology Data Exchange (ETDEWEB)
Kumar, Manoj [DSM Innovation, Inc., San Francisco, CA (United States)
2011-04-26
These are the slides from this presentation. Lignocellulosic biomass is the most abundant, least expensive renewable natural biological resource for the production of biobased products and bioenergy is important for the sustainable development of human civilization in 21st century. For making the fermentable sugars from lignocellulosic biomass, a reduction in cellulase production cost, an improvement in cellulase performance, and an increase in sugar yields are all vital to reduce the processing costs of biorefineries. Improvements in specific cellulase activities for non-complexed cellulase mixtures can be implemented through cellulase engineering based on rational design or directed evolution for each cellulase component enzyme, as well as on the reconstitution of cellulase components. In this paper, we will provide DSM's efforts in cellulase research and developments and focus on limitations. Cellulase improvement strategies based on directed evolution using screening on relevant substrates, screening for higher thermal tolerance based on activity screening approaches such as continuous culture using insoluble cellulosic substrates as a powerful selection tool for enriching beneficial cellulase mutants from the large library. We will illustrate why and how thermostable cellulases are vital for economic delivery of bioproducts from cellulosic biomass using biochemical conversion approach.
9. High Efficiency, Illumination Quality OLEDs for Lighting
Energy Technology Data Exchange (ETDEWEB)
Joseph Shiang; James Cella; Kelly Chichak; Anil Duggal; Kevin Janora; Chris Heller; Gautam Parthasarathy; Jeffery Youmans; Joseph Shiang
2008-03-31
. In 2003, a large area, OLED based illumination source was demonstrated that could provide light with a quality, quantity, and efficiency on par with what can be achieved with traditional light sources. The demonstration source was made by tiling together 16 separate 6-inch x 6-inch blue-emitting OLEDs. The efficiency, total lumen output, and lifetime of the OLED based illumination source were the same as what would be achieved with an 80 watt incandescent bulb. The devices had an average efficacy of 15 LPW and used solution-processed OLEDs. The individual 6-inch x 6-inch devices incorporated three technology strategies developed specifically for OLED lighting -- downconversion for white light generation, scattering for outcoupling efficiency enhancement, and a scalable monolithic series architecture to enable large area devices. The downconversion approach consists of optically coupling a blue-emitting OLED to a set of luminescent layers. The layers are chosen to absorb the blue OLED emission and then luminescence with high efficiency at longer wavelengths. The composition and number of layers are chosen so that the unabsorbed blue emission and the longer wavelength re-emission combine to make white light. A downconversion approach has the advantage of allowing a wide variety of colors to be made from a limited set of blue emitters. In addition, one does not have to carefully tune the emission wavelength of the individual electro-luminescent species within the OLED device in order to achieve white light. The downconversion architecture used to develop the 15LPW large area light source consisted of a polymer-based blue-emitting OLED and three downconversion layers. Two of the layers utilized perylene based dyes from BASF AG of Germany with high quantum efficiency (>98%) and one of the layers consisted of inorganic phosphor particles (Y(Gd)AG:Ce) with a quantum efficiency of {approx}85%. By independently varying the optical density of the downconversion layers, the
10. High-efficiency target-ion sources for RIB generation
International Nuclear Information System (INIS)
Alton, G.D.
1993-01-01
A brief review is given of high-efficiency ion sources which have been developed or are under development at ISOL facilities which show particular promise for use at existing, future, or radioactive ion beam (RIB) facilities now under construction. Emphasis will be placed on those sources which have demonstrated high ionization efficiency, species versatility, and operational reliability and which have been carefully designed for safe handling in the high level radioactivity radiation fields incumbent at such facilities. Brief discussions will also be made of the fundamental processes which affect the realizable beam intensities in target-ion sources. Among the sources which will be reviewed will be selected examples of state-of-the-art electron-beam plasma-type ion sources, thermal-ionization, surface-ionization, ECR, and selectively chosen ion source concepts which show promise for radioactive ion beam generation. A few advanced, chemically selective target-ion sources will be described, such as sources based on the use of laser-resonance ionization, which, in principle, offer a more satisfactory solution to isobaric contamination problems than conventional electromagnetic techniques. Particular attention will be given to the sources which have been selected for initial or future use at the Holifield Radioactive Ion Beam Facility now under construction at the Oak Ridge National Laboratory
11. Highly Efficient, Durable Regenerative Solid Oxide Stack, Phase I
Data.gov (United States)
National Aeronautics and Space Administration — Precision Combustion, Inc. (PCI) proposes to develop a highly efficient regenerative solid oxide stack design. Novel structural elements allow direct internal...
12. Hot nuclei studied with high efficiency neutron detectors
International Nuclear Information System (INIS)
Galin, J.
1990-01-01
We have shown the invaluable benefit that a high efficiency 4π neutron detector can bring to the study of reaction mechanisms following collisions of heavy nuclei at intermediate energy. Analysis requires Monte-Carlo simulations for comparison between experimental data and any emission model. In systematic measurements with projectiles of velocity corresponding to energies between 27 and 77 MeV/u, where both the influence of beam velocity and mass have been investigated separately, it has been shown that the projectile-target mass asymmetry, much more than velocity, has a decisive influence on energy dissipation. The closer the projectile mass to the target mass, the more energy is dissipated per unit mass of the considered projectile plus target system. The latter presents all the characteristics of a thermalized system, evaporating a copious number of light particles: up to about 40 neutrons (after efficiency correction) and 11 light charged particles in the most dissipative collisions between Kr+Au, and 90 neutrons for Pb+U with a yet unknown number of l.c.p. In the Kr experiment, these particles are isotropically emitted in the frame of a fused system, excited with 1.2 GeV. Moreover, l.c.p. exhibit Maxwellian energy distributions as in any standard evaporation process. We are now eager to better characterize the properties of the Pb+Au (U) systems for which about 1/3 of the neutrons are freed in a rather large fraction of all collisions. The thermalized energy should then approach very closely the total binding energy of the two interacting nuclei
13. HIGH EFFICIENCY DESULFURIZATION OF SYNTHESIS GAS
Energy Technology Data Exchange (ETDEWEB)
Kwang-Bok Yi; Anirban Mukherjee; Elizabeth J. Podlaha; Douglas P. Harrison
2004-03-01
Mixed metal oxides containing ceria and zirconia have been studied as high temperature desulfurization sorbents with the objective of achieving the DOE Vision 21 target of 1 ppmv or less H{sub 2}S in the product gas. The research was justified by recent results in this laboratory that showed that reduced CeO{sub 2}, designated CeOn (1.5 < n < 2.0), is capable of achieving the 1 ppmv target in highly reducing gas atmospheres. The addition of ZrO{sub 2} has improved the performance of oxidation catalysts and three-way automotive catalysts containing CeO{sub 2}, and was postulated to have similar beneficial effects on CeO{sub 2} desulfurization sorbents. An electrochemical method for synthesizing CeO{sub 2}-ZrO{sub 2} mixtures was developed and the products were characterized by XRD and TEM during year 01. Nanocrystalline particles having a diameter of about 5 nm and containing from approximately 10 mol% to 80 mol% ZrO{sub 2} were prepared. XRD analysis showed the product to be a solid solution at low ZrO{sub 2} contents with a separate ZrO{sub 2} phase emerging at higher ZrO{sub 2} levels. Unfortunately, the quantity of CeO{sub 2}-ZrO{sub 2} that could be prepared electrochemically was too small to permit desulfurization testing. Also during year 01 a laboratory-scale fixed-bed reactor was constructed for desulfurization testing. All components of the reactor and analytical systems that were exposed to low concentrations of H{sub 2}S were constructed of quartz, Teflon, or silcosteel. Reactor product gas composition as a function of time was determined using a Varian 3800 gas chromatograph equipped with a pulsed flame photometric detector (PFPD) for measuring low H{sub 2}S concentrations from approximately 0.1 to 10 ppmv, and a thermal conductivity detector (TCD) for higher concentrations of H{sub 2}S. Larger quantities of CeO{sub 2}-ZrO{sub 2} mixtures from other sources, including mixtures prepared in this laboratory using a coprecipitation procedure, were obtained
14. Series-Tuned High Efficiency RF-Power Amplifiers
DEFF Research Database (Denmark)
Vidkjær, Jens
2008-01-01
An approach to high efficiency RF-power amplifier design is presented. It addresses simultaneously efficiency optimization and peak voltage limitations when transistors are pushed towards their power limits.......An approach to high efficiency RF-power amplifier design is presented. It addresses simultaneously efficiency optimization and peak voltage limitations when transistors are pushed towards their power limits....
15. 40 CFR 761.71 - High efficiency boilers.
Science.gov (United States)
2010-07-01
... 40 Protection of Environment 30 2010-07-01 2010-07-01 false High efficiency boilers. 761.71... PROHIBITIONS Storage and Disposal § 761.71 High efficiency boilers. (a) To burn mineral oil dielectric fluid containing a PCB concentration of ≥50 ppm, but boiler shall comply with the following...
16. High efficiency nebulization for helium inductively coupled plasma mass spectrometry
International Nuclear Information System (INIS)
Jorabchi, Kaveh; McCormick, Ryan; Levine, Jonathan A.; Liu Huiying; Nam, S.-H.; Montaser, Akbar
2006-01-01
A pneumatically-driven, high efficiency nebulizer is explored for helium inductively coupled plasma mass spectrometry. The aerosol characteristics and analyte transport efficiencies of the high efficiency nebulizer for nebulization with helium are measured and compared to the results obtained with argon. Analytical performance indices of the helium inductively coupled plasma mass spectrometry are evaluated in terms of detection limits and precision. The helium inductively coupled plasma mass spectrometry detection limits obtained with the high efficiency nebulizer at 200 μL/min are higher than those achieved with the ultrasonic nebulizer consuming 2 mL/min solution, however, precision is generally better with high efficiency nebulizer (1-4% vs. 3-8% with ultrasonic nebulizer). Detection limits with the high efficiency nebulizer at 200 μL/min solution uptake rate approach those using ultrasonic nebulizer upon efficient desolvation with a heated spray chamber followed by a Peltier-cooled multipass condenser
17. A critical study of high efficiency deep grinding
International Nuclear Information System (INIS)
Johnstone, Iain
2002-01-01
The recent years, the aerospace industry in particular has embraced and actively pursued the development of stronger high performance materials, namely nickel based superalloys and hardwearing steels. This has resulted in a need for a more efficient method of machining, and this need was answered with the advent of High Efficiency Deep Grinding (HEDG). This relatively new process using Cubic Boron Nitride (CBN) electroplated grinding wheels has been investigated through experimental and theoretical means applied to two widely used materials, M50 bearing steel and IN718 nickel based superalloy. It has been shown that this grinding method using a stiff grinding centre such as the Edgetek 5-axis machine is a viable process. Using a number of experimental designs, produced results which were analysed using a variety of methods including visual assessment, sub-surface microscopy and surface analysis using a Scanning Electron Microscope (SEM), residual stress measurement using X-Ray Diffraction (XRD) techniques, Barkhausen Noise Amplitude (BNA) measurements, surface roughness and Vickers micro-hardness appraisal. It has been shown that the fundamentals of the HEDG process have been understood through experimental as well as theoretical means and that through the various thermal models used, grinding temperatures can be predicted to give more control over this dynamic process. The main contributions to knowledge are made up of a number of elements within the grinding environment, the most important being the demonstration of the HEDG effect, explanation of the phenomenon and the ability to model the process. It has also been shown that grinding is a dynamic process and factors such as wheel wear will result in a continuous change in the optimum grinding conditions for a given material and wheel combination. With the significance of these factors recognised, they can be accounted for within an industrial adaptive control scenario with the process engineer confident of a
18. High Efficiency Lighting with Integrated Adaptive Control (HELIAC), Phase II
Data.gov (United States)
National Aeronautics and Space Administration — The proposed project is the continued development of the High Efficiency Lighting with Integrated Adaptive Control (HELIAC) system. Solar radiation is not a viable...
19. High Efficiency Lighting with Integrated Adaptive Control (HELIAC), Phase I
Data.gov (United States)
National Aeronautics and Space Administration — The innovation of the proposed project is the development of High Efficiency Lighting with Integrated Adaptive Control (HELIAC) systems to drive plant growth. Solar...
20. High Efficiency S-Band 20 Watt Amplifier
Data.gov (United States)
National Aeronautics and Space Administration — This project includes the design and build of a prototype 20 W, high efficiency, S-Band amplifier. The design will incorporate the latest semiconductor technology,...
1. Process development for high-efficiency silicon solar cells
Energy Technology Data Exchange (ETDEWEB)
Gee, J.M.; Basore, P.A.; Buck, M.E.; Ruby, D.S.; Schubert, W.K.; Silva, B.L.; Tingley, J.W.
1991-12-31
Fabrication of high-efficiency silicon solar cells in an industrial environment requires a different optimization than in a laboratory environment. Strategies are presented for process development of high-efficiency silicon solar cells, with a goal of simplifying technology transfer into an industrial setting. The strategies emphasize the use of statistical experimental design for process optimization, and the use of baseline processes and cells for process monitoring and quality control. 8 refs.
2. The photonic nanowire: A highly efficient single-photon source
DEFF Research Database (Denmark)
Gregersen, Niels
2014-01-01
The photonic nanowire represents an attractive platform for a quantum light emitter. However, careful optical engineering using the modal method, which elegantly allows access to all relevant physical parameters, is crucial to ensure high efficiency.......The photonic nanowire represents an attractive platform for a quantum light emitter. However, careful optical engineering using the modal method, which elegantly allows access to all relevant physical parameters, is crucial to ensure high efficiency....
3. High-efficiency airfoil rudders applied to submarines
Directory of Open Access Journals (Sweden)
ZHOU Yimei
2017-03-01
Full Text Available Modern submarine design puts forward higher and higher requirements for control surfaces, and this creates a requirement for designers to constantly innovate new types of rudder so as to improve the efficiency of control surfaces. Adopting the high-efficiency airfoil rudder is one of the most effective measures for improving the efficiency of control surfaces. In this paper, we put forward an optimization method for a high-efficiency airfoil rudder on the basis of a comparative analysis of the various strengths and weaknesses of the airfoil, and the numerical calculation method is adopted to analyze the influence rule of the hydrodynamic characteristics and wake field by using the high-efficiency airfoil rudder and the conventional NACA rudder comparatively; at the same time, a model load test in a towing tank was carried out, and the test results and simulation calculation obtained good consistency:the error between them was less than 10%. The experimental results show that the steerage of a high-efficiency airfoil rudder is increased by more than 40% when compared with the conventional rudder, but the total resistance is close:the error is no more than 4%. Adopting a high-efficiency airfoil rudder brings much greater lifting efficiency than the total resistance of the boat. The results show that high-efficiency airfoil rudder has obvious advantages for improving the efficiency of control, giving it good application prospects.
4. HIGH EFFICIENCY GENERATION OF HYDROGEN FUELS USING NUCLEAR POWER
Energy Technology Data Exchange (ETDEWEB)
BROWN,LC; BESENBRUCH,GE; LENTSCH,RD; SCHULTZ,KR; FUNK,JF; PICKARD,PS; MARSHALL,AC; SHOWALTER,SK
2003-06-01
fossil fuels has trace contaminants (primarily carbon monoxide) that are detrimental to precious metal catalyzed fuel cells, as is now recognized by many of the world's largest automobile companies. Thermochemical hydrogen will not contain carbon monoxide as an impurity at any level. Electrolysis, the alternative process for producing hydrogen using nuclear energy, suffers from thermodynamic inefficiencies in both the production of electricity and in electrolytic parts of the process. The efficiency of electrolysis (electricity to hydrogen) is currently about 80%. Electric power generation efficiency would have to exceed 65% (thermal to electrical) for the combined efficiency to exceed the 52% (thermal to hydrogen) calculated for one thermochemical cycle. Thermochemical water-splitting cycles have been studied, at various levels of effort, for the past 35 years. They were extensively studied in the late 70s and early 80s but have received little attention in the past 10 years, particularly in the U.S. While there is no question about the technical feasibility and the potential for high efficiency, cycles with proven low cost and high efficiency have yet to be developed commercially. Over 100 cycles have been proposed, but substantial research has been executed on only a few. This report describes work accomplished during a three-year project whose objective is to ''define an economically feasible concept for production of hydrogen, by nuclear means, using an advanced high temperature nuclear reactor as the energy source.'' The emphasis of the first phase was to evaluate thermochemical processes which offer the potential for efficient, cost-effective, large-scale production of hydrogen from water in which the primary energy input is high temperature heat from an advanced nuclear reactor and to select one (or, at most three) for further detailed consideration. During Phase 1, an exhaustive literature search was performed to locate all cycles
5. Perovskite Solar Cells for High-Efficiency Tandems
Energy Technology Data Exchange (ETDEWEB)
McGehee, Michael [Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States); Buonassisi, Tonio [Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States)
2017-09-30
organic cation evolution and moisture penetration to overcome the often-reported thermal and environmental instability of metal halide perovskites. Previous perovskite-containing tandems utilized molybdenum oxide (MoOx) as a sputter buffer layer, but this has raised concerns over long-term stability, as the iodide in the perovskite can chemically react with MoOx. Mixed-cation perovskite solar cells have consistently outperformed their single-cation counterparts. The first perovskite device to exceed 20% PCE was fabricated with a mixture of methylammonium (MA) and formamidinium (FA). Recent reports have shown promising results with the introduction of cesium mixtures, enabling high efficiencies with improved photo-, moisture, and thermal stability. The increased moisture and thermal stability are especially important as they broaden the parameter space for processing on top of the perovskite, enabling the deposition of metal oxide contacts through atomic layer deposition (ALD) or chemical vapor deposition (CVD) that may require elevated temperatures or water as a counter reagent. Both titanium dioxide (TiO2) and tin oxide (SnO2) have consistently proven to be effective electron-selective contacts for perovskite solar cells and both can be deposited via ALD at temperatures below 150 °C. We introduced a bilayer of SnO2 and zinc tin oxide (ZTO) that can be deposited by either low-temperature ALD or pulsed-CVD as a window layer with minimal parasitic absorption, efficient electron extraction, and sufficient buffer properties to prevent the organic and perovskite layers from damage during the subsequent sputter deposition of a transparent ITO electrode. We explored pulsed-CVD as a modified ALD process with a continual, rather than purely step-wise, growth component in order to considerably reduce the process time of the SnO2 deposition process and minimize potential perovskite degradation. These layers, when
6. Highly Efficient Fumed Silica Nanoparticles for Peptide Bond Formation: Converting Alanine to Alanine Anhydride.
Science.gov (United States)
Guo, Chengchen; Jordan, Jacob S; Yarger, Jeffery L; Holland, Gregory P
2017-05-24
In this work, thermal condensation of alanine adsorbed on fumed silica nanoparticles is investigated using thermal analysis and multiple spectroscopic techniques, including infrared (IR), Raman, and nuclear magnetic resonance (NMR) spectroscopies. Thermal analysis shows that adsorbed alanine can undergo thermal condensation, forming peptide bonds within a short time period and at a lower temperature (∼170 °C) on fumed silica nanoparticle surfaces than that in bulk (∼210 °C). Spectroscopic results further show that alanine is converted to alanine anhydride with a yield of 98.8% during thermal condensation. After comparing peptide formation on solution-derived colloidal silica nanoparticles, it is found that fumed silica nanoparticles show much better efficiency and selectivity than solution-derived colloidal silica nanoparticles for synthesizing alanine anhydride. Furthermore, Raman spectroscopy provides evidence that the high efficiency for fumed silica nanoparticles is likely related to their unique surface features: the intrinsic high population of strained ring structures present at the surface. This work indicates the great potential of fumed silica nanoparticles in synthesizing peptides with high efficiency and selectivity.
7. Low Temperature Combustion Demonstrator for High Efficiency Clean Combustion
Energy Technology Data Exchange (ETDEWEB)
Ojeda, William de
2010-07-31
The project which extended from November 2005 to May of 2010 demonstrated the application of Low Temperature Combustion (LTC) with engine out NOx levels of 0.2 g/bhp-hr throughout the program target load of 12.6bar BMEP. The project showed that the range of loads could be extended to 16.5bar BMEP, therefore matching the reference lug line of the base 2007 MY Navistar 6.4L V8 engine. Results showed that the application of LTC provided a dramatic improvement over engine out emissions when compared to the base engine. Furthermore LTC improved thermal efficiency by over 5% from the base production engine when using the steady state 13 mode composite test as a benchmark. The key enablers included improvements in the air, fuel injection, and cooling systems made in Phases I and II. The outcome was the product of a careful integration of each component under an intelligent control system. The engine hardware provided the conditions to support LTC and the controller provided the necessary robustness for a stable combustion. Phase III provided a detailed account on the injection strategy used to meet the high load requirements. During this phase, the control strategy was implemented in a production automotive grade ECU to perform cycle-by-cycle combustion feedback on each of the engine cylinders. The control interacted on a cycle base with the injection system and with the Turbo-EGR systems according to their respective time constants. The result was a unique system that could, first, help optimize the combustion system and maintain high efficiency, and secondly, extend the steady state results to the transient mode of operation. The engine was upgraded in Phase IV with a Variable Valve Actuation system and a hybrid EGR loop. The impact of the more versatile EGR loop did not provide significant advantages, however the application of VVA proved to be an enabler to further extend the operation of LTC and gain considerable benefits in fuel economy and soot reduction. Finally
8. Charge transport in highly efficient iridium cored electrophosphorescent dendrimers
Science.gov (United States)
Markham, Jonathan P. J.; Samuel, Ifor D. W.; Lo, Shih-Chun; Burn, Paul L.; Weiter, Martin; Bässler, Heinz
2004-01-01
Electrophosphorescent dendrimers are promising materials for highly efficient light-emitting diodes. They consist of a phosphorescent core onto which dendritic groups are attached. Here, we present an investigation into the optical and electronic properties of highly efficient phosphorescent dendrimers. The effect of dendrimer structure on charge transport and optical properties is studied using temperature-dependent charge-generation-layer time-of-flight measurements and current voltage (I-V) analysis. A model is used to explain trends seen in the I-V characteristics. We demonstrate that fine tuning the mobility by chemical structure is possible in these dendrimers and show that this can lead to highly efficient bilayer dendrimer light-emitting diodes with neat emissive layers. Power efficiencies of 20 lm/W were measured for devices containing a second-generation (G2) Ir(ppy)3 dendrimer with a 1,3,5-tris(2-N-phenylbenzimidazolyl)benzene electron transport layer.
9. Progress of OLED devices with high efficiency at high luminance
Science.gov (United States)
Nguyen, Carmen; Ingram, Grayson; Lu, Zhenghong
2014-03-01
Organic light emitting diodes (OLEDs) have progressed significantly over the last two decades. For years, OLEDs have been promoted as the next generation technology for flat panel displays and solid-state lighting due to their potential for high energy efficiency and dynamic range of colors. Although high efficiency can readily be obtained at low brightness levels, a significant decline at high brightness is commonly observed. In this report, we will review various strategies for achieving highly efficient phosphorescent OLED devices at high luminance. Specifically, we will provide details regarding the performance and general working principles behind each strategy. We will conclude by looking at how some of these strategies can be combined to produce high efficiency white OLEDs at high brightness.
10. A nuclear standard high-efficiency adsorber for iodine
International Nuclear Information System (INIS)
Wang Jianmin; Qian Yinge
1988-08-01
The structure of a nuclear standard high-efficiency adsorber, adsorbent and its performance are introduced. The performance and structure were compared with the same kind product of other firms. The results show that the leakage rate is less than 0.005%
11. High Efficiency Power Converter for Low Voltage High Power Applications
DEFF Research Database (Denmark)
Nymand, Morten
The topic of this thesis is the design of high efficiency power electronic dc-to-dc converters for high-power, low-input-voltage to high-output-voltage applications. These converters are increasingly required for emerging sustainable energy systems such as fuel cell, battery or photo voltaic based...
12. Optimization of high-efficiency components; Optimieren auf hohem Niveau
Energy Technology Data Exchange (ETDEWEB)
Neumann, Eva
2009-07-01
High efficiency is a common feature of modern current inverters and is not a unique selling proposition. Other factors that influence the buyer's decision are cost reduction, reliability and service, optimum grid integration, and the challenges of the competitive thin film technology. (orig.)
13. Orion, a high efficiency 4π neutron detector
International Nuclear Information System (INIS)
Crema, E.; Piasecki, E.; Wang, X.M.; Doubre, H.; Galin, J.; Guerreau, D.; Pouthas, J.; Saint-Laurent, F.
1990-01-01
In intermediate energy heavy ion collisions the multiplicity of emitted neutrons is strongly connected to energy dissipation and to impact parameter. We present the 4π detector ORION, a high efficiency liquid scintillator detector which permits to get information on the multiplicity of neutrons measured event-wise and on the spatial distribution of these neutrons [fr
14. High-Efficiency Klystron Design for the CLIC Project
CERN Document Server
Mollard, Antoine; Peauger, Franck; Plouin, Juliette; Beunas, Armel; Marchesin, Rodolphe
2017-01-01
The CLIC project requests new type of RF sources for the high power conditioning of the accelerating cavities. We are working on the development of a new kind of high-efficiency klystron to fulfill this need. This work is performed under the EuCARD-2 European program and involves theoretical and experimental study of a brand new klystron concept.
15. High efficiency hydrodynamic DNA fragmentation in a bubbling system
NARCIS (Netherlands)
Li, Lanhui; Jin, Mingliang; Sun, Chenglong; Wang, Xiaoxue; Xie, Shuting; Zhou, Guofu; Van Den Berg, Albert; Eijkel, Jan C.T.; Shui, Lingling
2017-01-01
DNA fragmentation down to a precise fragment size is important for biomedical applications, disease determination, gene therapy and shotgun sequencing. In this work, a cheap, easy to operate and high efficiency DNA fragmentation method is demonstrated based on hydrodynamic shearing in a bubbling
16. High efficiency confinement mode by electron cyclotron heating
International Nuclear Information System (INIS)
Funahashi, Akimasa
1987-01-01
In the medium size nuclear fusion experiment facility JFT-2M in the Japan Atomic Energy Research Institute, the research on the high efficiency plasma confinement mode has been advanced, and in the experiment in June, 1987, the formation of a high efficiency confinement mode was successfully controlled by electron cyclotron heating, for the first time in the world. This result further advanced the control of the formation of a high efficiency plasma confinement mode and the elucidation of the physical mechanism of that mode, and promoted the research and development of the plasma heating by electron cyclotron heating. In this paper, the recent results of the research on a high efficiency confinement mode at the JFT-2M are reported, and the role of the JFT-2M and the experiment on the improvement of core plasma performance are outlined. Now the plasma temperature exceeding 100 million deg C has been attained in large tokamaks, and in medium size facilities, the various measures for improving confinement performance are to be brought forth and their scientific basis is elucidated to assist large facilities. The JFT-2M started the operation in April, 1983, and has accumulated the results smoothly since then. (Kako, I.)
17. Super Boiler: First Generation, Ultra-High Efficiency Firetube Boiler
Energy Technology Data Exchange (ETDEWEB)
None
2006-06-01
This factsheet describes a research project whose goal is to develop and demonstrate a first-generation ultra-high-efficiency, ultra-low emissions, compact gas-fired package boiler (Super Boiler), and formulate a long-range RD&D plan for advanced boiler technology out to the year 2020.
18. High-efficient solar cells with porous silicon
International Nuclear Information System (INIS)
Migunova, A.A.
2002-01-01
It has been shown that the porous silicon is multifunctional high-efficient coating on silicon solar cells, modifies its surface and combines in it self antireflection and passivation properties., The different optoelectronic effects in solar cells with porous silicon were considered. The comparative parameters of uncovered photodetectors also solar cells with porous silicon and other coatings were resulted. (author)
19. Nuclear Forensics: Measurements of Uranium Oxides Using Time-of-Flight Secondary Ion Mass Spectrometry (TOF-SIMS)
Science.gov (United States)
2010-03-01
Isotope Ratio Analysis of Actinides , Fission Products, and Geolocators by High- efficiency Multi-collector Thermal Ionization Mass Spectrometry...Information, 1999. Hou, Xiaolin, and Per Roos. “ Critical Comparison of radiometric and Mass Spectrometric Methods for the Determination of...NUCLEAR FORENSICS: MEASUREMENTS OF URANIUM OXIDES USING TIME-OF-FLIGHT SECONDARY ION MASS
20. 3rd symposium on high-efficiency boiler technology: potential, performance, shortcomings of natural gas fuelled high-efficiency boilers
International Nuclear Information System (INIS)
1993-01-01
The brochure contains abstracts of the papers presented at the symposium. The potential, performance and marketing problems of natural gas high-efficiency boiler systems are outlined, and new ideas are presented for gas utilities, producers of appliances, fitters, and chimneysweeps. 13 papers are available as separate regards in this database. (HW) [de
1. The high efficiency steel filters for nuclear air cleaning
International Nuclear Information System (INIS)
Bergman, W.; Larsen, G.; Lopez, R.; Williams, K.; Violet, C.
1990-08-01
We have, in cooperation with industry, developed high-efficiency filters made from sintered stainless-steel fibers for use in several air-cleaning applications in the nuclear industry. These filters were developed to overcome the failure modes in present high-efficiency particulate air (HEPA) filters. HEPA filters are made from glass paper and glue, and they may fail when they get hot or wet and when they are overpressured. In developing our steel filters, we first evaluated the commercially available stainless-steel filter media made from sintered powder and sintered fiber. The sintered-fiber media performed much better than sintered-powder media, and the best media had the smallest fiber diameter. Using the best media, we then built prototype filters for venting compressed gases and evaluated them in our automated filter tester. 12 refs., 20 figs
2. High efficiency steel filters for nuclear air cleaning
International Nuclear Information System (INIS)
Bergman, W.; Conner, J.; Larsen, G.; Lopez, R.; Turner, C.; Vahla, G.; Violet, C.; Williams, K.
1991-01-01
The authors have, in cooperation with industry, developed high-efficiency filters made from sintered stainless-steel fibers for use in several air-cleaning applications in the nuclear industry. These filters were developed to overcome the failure modes in present high-efficiently particulate air (HEPA) filters. HEPA filters are made from glass paper and glue, and they may fail when they get hot or wet and when they are overpressured. In developing steel filters, they first evaluated the commercially available stainless-steel filter media made from sintered powder and sintered fiber. The sintered-fiber media performed much better than sintered-powder media, and the best media had the smallest fiber diameter. Using the best media, prototype filters were then built for venting compressed gases and evaluated in their automated filter tester
3. Development of high-efficiency solar cells on silicon web
Science.gov (United States)
Meier, D. L.; Greggi, J.; Okeeffe, T. W.; Rai-Choudhury, P.
1986-01-01
Work was performed to improve web base material with a goal of obtaining solar cell efficiencies in excess of 18% (AM1). Efforts in this program are directed toward identifying carrier loss mechanisms in web silicon, eliminating or reducing these mechanisms, designing a high efficiency cell structure with the aid of numerical models, and fabricating high efficiency web solar cells. Fabrication techniques must preserve or enhance carrier lifetime in the bulk of the cell and minimize recombination of carriers at the external surfaces. Three completed cells were viewed by cross-sectional transmission electron microscopy (TEM) in order to investigate further the relation between structural defects and electrical performance of web cells. Consistent with past TEM examinations, the cell with the highest efficiency (15.0%) had no dislocations but did have 11 twin planes.
4. Potential high efficiency solar cells: Applications from space photovoltaic research
Science.gov (United States)
Flood, D. J.
1986-01-01
NASA involvement in photovoltaic energy conversion research development and applications spans over two decades of continuous progress. Solar cell research and development programs conducted by the Lewis Research Center's Photovoltaic Branch have produced a sound technology base not only for the space program, but for terrestrial applications as well. The fundamental goals which have guided the NASA photovoltaic program are to improve the efficiency and lifetime, and to reduce the mass and cost of photovoltaic energy conversion devices and arrays for use in space. The major efforts in the current Lewis program are on high efficiency, single crystal GaAs planar and concentrator cells, radiation hard InP cells, and superlattice solar cells. A brief historical perspective of accomplishments in high efficiency space solar cells will be given, and current work in all of the above categories will be described. The applicability of space cell research and technology to terrestrial photovoltaics will be discussed.
5. Irradiation effects on high efficiency Si solar cells
International Nuclear Information System (INIS)
Nguyen Duy, T.; Amingual, D.; Colardelle, P.; Bernard, J.
1974-01-01
By optimizing the diffusion parameters, high efficiency cells are obtained with 2ohmsxcm (13.5% AMO) and 10ohmsxcm (12.5% AMO) silicon material. These new cells have been submitted to radiation tests under 1MeV, 2MeV electrons and 2.5MeV protons. Their behavior under irradiation is found to be dependent only on the bulk material. By using the same resistivity silicon, the rate of degradation is exactly the same than those of conventional cells. The power increase, due to a better superficial response of the cell, is maintained after irradiation. These results show that new high efficiency cells offer an E.O.L. power higher than conventional cells [fr
6. Highly efficient electron vortex beams generated by nanofabricated phase holograms
Energy Technology Data Exchange (ETDEWEB)
Grillo, Vincenzo, E-mail: vincenzo.grillo@nano.cnr.it [CNR-Istituto Nanoscienze, Centro S3, Via G Campi 213/a, I-41125 Modena (Italy); CNR-IMEM Parco Area delle Scienze 37/A, I-43124 Parma (Italy); Carlo Gazzadi, Gian [CNR-Istituto Nanoscienze, Centro S3, Via G Campi 213/a, I-41125 Modena (Italy); Karimi, Ebrahim [CNR-Istituto Nanoscienze, Centro S3, Via G Campi 213/a, I-41125 Modena (Italy); Department of Physics, University of Ottawa, 150 Louis Pasteur, Ottawa, Ontario K1N 6N5 (Canada); Mafakheri, Erfan [Dipartimento di Fisica Informatica e Matematica, Università di Modena e Reggio Emilia, via G Campi 213/a, I-41125 Modena (Italy); Boyd, Robert W. [Department of Physics, University of Ottawa, 150 Louis Pasteur, Ottawa, Ontario K1N 6N5 (Canada); Frabboni, Stefano [CNR-Istituto Nanoscienze, Centro S3, Via G Campi 213/a, I-41125 Modena (Italy); Dipartimento di Fisica Informatica e Matematica, Università di Modena e Reggio Emilia, via G Campi 213/a, I-41125 Modena (Italy)
2014-01-27
We propose an improved type of holographic-plate suitable for the shaping of electron beams. The plate is fabricated by a focused ion beam on a silicon nitride membrane and introduces a controllable phase shift to the electron wavefunction. We adopted the optimal blazed-profile design for the phase hologram, which results in the generation of highly efficient (25%) electron vortex beams. This approach paves the route towards applications in nano-scale imaging and materials science.
7. Holography as a highly efficient RG flow I: Rephrasing gravity
OpenAIRE
Behr, Nicolas; Kuperstein, Stanislav; Mukhopadhyay, Ayan
2015-01-01
We investigate how the holographic correspondence can be reformulated as a generalisation of Wilsonian RG flow in a strongly interacting large $N$ quantum field theory. We firstly define a \\textit{highly efficient RG flow} as one in which the Ward identities related to local conservation of energy, momentum and charges preserve the same form at each scale -- to achieve this it is necessary to redefine the background metric and external sources at each scale as functionals of the effective sin...
8. Sm , Bi phosphors with high efficiency white-light-emittin
2017-08-29
Aug 29, 2017 ... Therefore, researches on high efficiency red phos- phors are very important. So far ..... ing concentration and reached a maximum at y = 8 mol%. A .... [10] Xue L P, Wang Y J, Lv P W, Chen D G, Lin Z, Liang J K et al. 2009 Crystal ... [28] Liu J, Xu B, Song C, Luo H, Zou X, Han L et al 2012 Cryst-. EngComm.
9. High-Efficient Low-Cost Photovoltaics Recent Developments
CERN Document Server
2009-01-01
A bird's-eye view of the development and problems of recent photovoltaic cells and systems and prospects for Si feedstock is presented. High-efficient low-cost PV modules, making use of novel efficient solar cells (based on c-Si or III-V materials), and low cost solar concentrators are in the focus of this book. Recent developments of organic photovoltaics, which is expected to overcome its difficulties and to enter the market soon, are also included.
10. Highly efficient procedure for the transesterification of vegetable oil
Energy Technology Data Exchange (ETDEWEB)
Liang, Xuezheng; Gao, Shan; He, Mingyuan [Shanghai Key Laboratory of Green Chemistry and Chemical Process, Department of Chemistry, East China Normal University, Shanghai 200062 (China); Yang, Jianguo [Shanghai Key Laboratory of Green Chemistry and Chemical Process, Department of Chemistry, East China Normal University, Shanghai 200062 (China); Energy Institute, Department of Materials Science and Engineering, Pennsylvania State University, University Park, PA 16802 (United States)
2009-10-15
The highly efficient procedure has been developed for the synthesis of biodiesel from vegetable oil and methanol. The KF/MgO has been selected as the most efficient catalyst for the reactions with the yield of 99.3%. Operational simplicity, without need of the purification of raw vegetable oil, low cost of the catalyst used, high activities, no saponification and reusability are the key features of this methodology. (author)
11. Stabilization void-fill encapsulation high-efficiency particulate filters
International Nuclear Information System (INIS)
Alexander, R.G.; Stewart, W.E.; Phillips, S.J.; Serkowski, M.M.; England, J.L.; Boynton, H.C.
1994-05-01
This report discusses high-efficiency particulate air (HEPA) filter systems that which are contaminated with radionuclides are part of the nuclear fuel processing systems conducted by the US Department of Energy (DOE) and require replacement and safe and efficient disposal for plant safety. Two K-3 HEPA filters were removed from service, placed burial boxes, buried, and safely and efficiently stabilized remotely which reduced radiation exposure to personnel and the environment
12. Global climate change: Mitigation opportunities high efficiency large chiller technology
Energy Technology Data Exchange (ETDEWEB)
Stanga, M.V.
1997-12-31
This paper, comprised of presentation viewgraphs, examines the impact of high efficiency large chiller technology on world electricity consumption and carbon dioxide emissions. Background data are summarized, and sample calculations are presented. Calculations show that presently available high energy efficiency chiller technology has the ability to substantially reduce energy consumption from large chillers. If this technology is widely implemented on a global basis, it could reduce carbon dioxide emissions by 65 million tons by 2010.
13. Design of High Efficiency Illumination for LED Lighting
OpenAIRE
Chang, Yong-Nong; Cheng, Hung-Liang; Kuo, Chih-Ming
2013-01-01
A high efficiency illumination for LED street lighting is proposed. For energy saving, this paper uses Class-E resonant inverter as main electric circuit to improve efficiency. In addition, single dimming control has the best efficiency, simplest control scheme and lowest circuit cost among other types of dimming techniques. Multiple serial-connected transformers used to drive the LED strings as they can provide galvanic isolation and have the advantage of good current distribution against de...
14. High-efficiency pumps drastically reduce energy consumption
Energy Technology Data Exchange (ETDEWEB)
Anon
2002-05-01
Wilo's Stratos pumps for air conditioning and other domestic heating applications combine the advantages of wet runner technology with an innovative electronic commutator motor. The energy consumption of these high-efficiency pumps is halved compared with similar wet runner designs. With vast numbers of pumps used in buildings across Europe alone, the adoption of this technology potentially offers significant energy sayings. (Author)
15. The emerging High Efficiency Video Coding standard (HEVC)
International Nuclear Information System (INIS)
Raja, Gulistan; Khan, Awais
2013-01-01
High definition video (HDV) is becoming popular day by day. This paper describes the performance analysis of latest upcoming video standard known as High Efficiency Video Coding (HEVC). HEVC is designed to fulfil all the requirements for future high definition videos. In this paper, three configurations (intra only, low delay and random access) of HEVC are analyzed using various 480p, 720p and 1080p high definition test video sequences. Simulation results show the superior objective and subjective quality of HEVC
16. Highly efficient electron vortex beams generated by nanofabricated phase holograms
International Nuclear Information System (INIS)
Grillo, Vincenzo; Carlo Gazzadi, Gian; Karimi, Ebrahim; Mafakheri, Erfan; Boyd, Robert W.; Frabboni, Stefano
2014-01-01
We propose an improved type of holographic-plate suitable for the shaping of electron beams. The plate is fabricated by a focused ion beam on a silicon nitride membrane and introduces a controllable phase shift to the electron wavefunction. We adopted the optimal blazed-profile design for the phase hologram, which results in the generation of highly efficient (25%) electron vortex beams. This approach paves the route towards applications in nano-scale imaging and materials science
17. 3D-Printed, All-in-One Evaporator for High-Efficiency Solar Steam Generation under 1 Sun Illumination.
Science.gov (United States)
Li, Yiju; Gao, Tingting; Yang, Zhi; Chen, Chaoji; Luo, Wei; Song, Jianwei; Hitz, Emily; Jia, Chao; Zhou, Yubing; Liu, Boyang; Yang, Bao; Hu, Liangbing
2017-07-01
Using solar energy to generate steam is a clean and sustainable approach to addressing the issue of water shortage. The current challenge for solar steam generation is to develop easy-to-manufacture and scalable methods which can convert solar irradiation into exploitable thermal energy with high efficiency. Although various material and structure designs have been reported, high efficiency in solar steam generation usually can be achieved only at concentrated solar illumination. For the first time, 3D printing to construct an all-in-one evaporator with a concave structure for high-efficiency solar steam generation under 1 sun illumination is used. The solar-steam-generation device has a high porosity (97.3%) and efficient broadband solar absorption (>97%). The 3D-printed porous evaporator with intrinsic low thermal conductivity enables heat localization and effectively alleviates thermal dissipation to the bulk water. As a result, the 3D-printed evaporator has a high solar steam efficiency of 85.6% under 1 sun illumination (1 kW m -2 ), which is among the best compared with other reported evaporators. The all-in-one structure design using the advanced 3D printing fabrication technique offers a new approach to solar energy harvesting for high-efficiency steam generation. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
18. High-efficiency white OLEDs based on small molecules
Science.gov (United States)
Hatwar, Tukaram K.; Spindler, Jeffrey P.; Ricks, M. L.; Young, Ralph H.; Hamada, Yuuhiko; Saito, N.; Mameno, Kazunobu; Nishikawa, Ryuji; Takahashi, Hisakazu; Rajeswaran, G.
2004-02-01
Eastman Kodak Company and SANYO Electric Co., Ltd. recently demonstrated a 15" full-color, organic light-emitting diode display (OLED) using a high-efficiency white emitter combined with a color-filter array. Although useful for display applications, white emission from organic structures is also under consideration for other applications, such as solid-state lighting, where high efficiency and good color rendition are important. By incorporating adjacent blue and orange emitting layers in a multi-layer structure, highly efficient, stable white emission has been attained. With suitable host and dopant combinations, a luminance yield of 20 cd/A and efficiency of 8 lm/W have been achieved at a drive voltage of less than 8 volts and luminance level of 1000 cd/m2. The estimated external efficiency of this device is 6.3% and a high level of operational stability is observed. To our knowledge, this is the highest performance reported so far for white organic electroluminescent devices. We will review white OLED technology and discuss the fabrication and operating characteristics of these devices.
19. High Efficiency, Low Cost Parabolic Dish System for Cogeneration of Electricity and Heat
Science.gov (United States)
Chayet, Haim; Lozovsky, Ilan; Kost, Ori; Loeckenhoff, Ruediger; Rasch, Klaus-Dieter
2010-10-01
Highly efficient combined heat and power generating system based on CPV technology using unique dish design consisting of multiple simple flat mirrors mounted on a plastic parabolic surface. The dish of total aperture area of 11 m2 focuses 10.3 kWp onto a heat and electricity generating receiver. The receiver comprises a water cooled, dense triple junction cell array of 176 cm2 aperture area. A unique arrangement of the cells compensates for the non-uniformity of the reflected flux. Depending on the flow rate, the temperature of the hot water can be adjusted to suit from temperatures for domestic use, to temperatures suited for process heat. The output of 2.3 kWp electrical and 5.5 kWp thermal power from one dish system represent 20 to 21% electrical and 50% thermal conversion efficiency adding to 70% overall system efficiency.
20. Combustion Mode Design with High Efficiency and Low Emissions Controlled by Mixtures Stratification and Fuel Reactivity
Directory of Open Access Journals (Sweden)
Hu eWang
2015-08-01
Full Text Available This paper presents a review on the combustion mode design with high efficiency and low emissions controlled by fuel reactivity and mixture stratification that have been conducted in the authors’ group, including the charge reactivity controlled homogeneous charge compression ignition (HCCI combustion, stratification controlled premixed charge compression ignition (PCCI combustion, and dual-fuel combustion concepts controlled by both fuel reactivity and mixture stratification. The review starts with the charge reactivity controlled HCCI combustion, and the works on HCCI fuelled with both high cetane number fuels, such as DME and n-heptane, and high octane number fuels, such as methanol, natural gas, gasoline and mixtures of gasoline/alcohols, are reviewed and discussed. Since single fuel cannot meet the reactivity requirements under different loads to control the combustion process, the studies related to concentration stratification and dual-fuel charge reactivity controlled HCCI combustion are then presented, which have been shown to have the potential to achieve effective combustion control. The efforts of using both mixture and thermal stratifications to achieve the auto-ignition and combustion control are also discussed. Thereafter, both charge reactivity and mixture stratification are then applied to control the combustion process. The potential and capability of thermal-atmosphere controlled compound combustion mode and dual-fuel reactivity controlled compression ignition (RCCI/highly premixed charge combustion (HPCC mode to achieve clean and high efficiency combustion are then presented and discussed. Based on these results and discussions, combustion mode design with high efficiency and low emissions controlled by fuel reactivity and mixtures stratification in the whole operating range is proposed.
1. Polyphenols attached graphene nanosheets for high efficiency NIR mediated photodestruction of cancer cells
International Nuclear Information System (INIS)
2013-01-01
Green tea-reduced graphene oxide (GT-rGO) sheets have been exploited for high efficiency near infrared (NIR) photothermal therapy of HT29 and SW48 colon cancer cells. The biocompatibility of GT-rGO sheets was investigated by means of MTT assays. The polyphenol constituents of GT-rGO act as effective targeting ligands for the attachment of rGO to the surface of cancer cells, as confirmed by the cell granularity test in flow cytometry assays and also by scanning electron microscopy. The photo-thermal destruction of higher metastatic cancer cells (SW48) is found to be more than 20% higher than that of the lower metastatic one (HT29). The photo-destruction efficiency factor of the GT-rGO is found to be at least two orders of magnitude higher than other carbon-based nano-materials. Such excellent cancer cell destruction efficiency provided application of a low concentration of rGO (3 mg/L) and NIR laser power density (0.25 W/cm 2 ) in our photo-thermal therapy of cancer cells. Highlights: ► Attachment of polyphenol groups to graphene nano-sheets during reduction process by green tea. ► Selective attachment of polyphenols to cancer cell membrane. ► High efficiency photothermal therapy of colon cancer cells with green-tea reduced graphene oxide
2. Towards a utilisation of transient processing in the technology of high efficiency silicon solar cells
International Nuclear Information System (INIS)
Eichhammer, W.
1989-01-01
The utilization of transient processing in the technology of high efficient silicon solar cells is investigated. An ultraviolet laser (an ArF pulsed excimer laser working at 193 nm) is applied. Laser processing induces only a short superficial melting of the material and does not modify the transport properties in the base of the material. This mode of processing associated to ion implantation to form the junction as well as an oxide layer in an atmosphere of oxygen. The volume was left entirely cold in this process. The results of the investigation show: that an entirely cold process of solar cell fabrication needs a thermal treatment at a temperature around 600 C; that the oxides obtained are not satisfying as passivating layers; and that the Rapid Thermal Processing (RTP) induced recombination centers are not directly related to the quenching step but a consequence of the presence of metal impurities. The utilisation of transient processing in the adiabatic regime (laser) and in the rapid isothermal regime (RTP) are possible as two complementary techniques for the realization of high efficiency solar cells
3. Macroporous Double-Network Hydrogel for High-Efficiency Solar Steam Generation Under 1 sun Illumination.
Science.gov (United States)
Yin, Xiangyu; Zhang, Yue; Guo, Qiuquan; Cai, Xiaobing; Xiao, Junfeng; Ding, Zhifeng; Yang, Jun
2018-04-04
Solar steam generation is one of the most promising solar-energy-harvesting technologies to address the issue of water shortage. Despite intensive efforts to develop high-efficiency solar steam generation devices, challenges remain in terms of the relatively low solar thermal efficiency, complicated fabrications, high cost, and difficulty in scaling up. Herein, a double-network hydrogel with a porous structure (p-PEGDA-PANi) is demonstrated for the first time as a flexible, recyclable, and efficient photothermal platform for low-cost and scalable solar steam generation. As a novel photothermal platform, the p-PEGDA-PANi involves all necessary properties of efficient broadband solar absorption, exceptional hydrophilicity, low heat conductivity, and porous structure for high-efficiency solar steam generation. As a result, the hydrogel-based solar steam generator exhibits a maximum solar thermal efficiency of 91.5% with an evaporation rate of 1.40 kg m -2 h -1 under 1 sun illumination, which is comparable to state-of-the-art solar steam generation devices. Furthermore, the good durability and environmental stability of the p-PEGDA-PANi hydrogel enables a convenient recycling and reusing process toward real-life applications. The present research not only provides a novel photothermal platform for solar energy harvest but also opens a new avenue for the application of the hydrogel materials in solar steam generation.
4. Manipulation of radicals and ions in LFICP-aided fabrication of high efficiency solar cells
International Nuclear Information System (INIS)
Xu, S.
2013-01-01
In this talk, we report on the development and diagnostics of low frequency inductively coupled plasma (LFICP) reactor for fabrication of high efficiency silicon solar cells. Chemically active, thermally non-equilibrium plasma possess unique advantages for manipulation of plasma-generated radicals/ions and overall control of growth and self-organization processes that are crucial for fabrication of photovoltaic materials and solar cells. In low frequency inductively coupled plasmas, generation, selection and control of densities and fluxes of the radicals and ions can easily be controlled by the electron energy distributions and other plasma parameters. The electric field and thermal forces guide selective delivery of the radicals to the surface. Specific substrate activation and temperature determine the ion/heat fluxes from the gas phase to the charged surfaces. Detailed discussion includes the inter-connection between in-situ plasma diagnostics (Optical Emission Spectroscopy, Langmuir Probe diagnostics, and Quadruple Mass Spectrometry) and ex-situ material characterization (XRD, Raman, FTIR EDX, UV/Vis, SEM, Hall-effect and others). Special emphasis is paid to the identification and control strategies of the plasma-generated radicals/ions existed in both the ionized gas phase and on the deposition surfaces. We will show how radicals and ions can be manipulated to meet the structural, optical and electronic requirements for high efficiency photovoltaic cells. Solar cell fabricated by the LFICP plasma exhibits an extraordinarily photovoltaic performance with energy conversion efficiency exceeding 18%. (author)
5. Lightweight High Efficiency Electric Motors for Space Applications
Science.gov (United States)
Robertson, Glen A.; Tyler, Tony R.; Piper, P. J.
2011-01-01
Lightweight high efficiency electric motors are needed across a wide range of space applications from - thrust vector actuator control for launch and flight applications to - general vehicle, base camp habitat and experiment control for various mechanisms to - robotics for various stationary and mobile space exploration missions. QM Power?s Parallel Path Magnetic Technology Motors have slowly proven themselves to be a leading motor technology in this area; winning a NASA Phase II for "Lightweight High Efficiency Electric Motors and Actuators for Low Temperature Mobility and Robotics Applications" a US Army Phase II SBIR for "Improved Robot Actuator Motors for Medical Applications", an NSF Phase II SBIR for "Novel Low-Cost Electric Motors for Variable Speed Applications" and a DOE SBIR Phase I for "High Efficiency Commercial Refrigeration Motors" Parallel Path Magnetic Technology obtains the benefits of using permanent magnets while minimizing the historical trade-offs/limitations found in conventional permanent magnet designs. The resulting devices are smaller, lower weight, lower cost and have higher efficiency than competitive permanent magnet and non-permanent magnet designs. QM Power?s motors have been extensively tested and successfully validated by multiple commercial and aerospace customers and partners as Boeing Research and Technology. Prototypes have been made between 0.1 and 10 HP. They are also in the process of scaling motors to over 100kW with their development partners. In this paper, Parallel Path Magnetic Technology Motors will be discussed; specifically addressing their higher efficiency, higher power density, lighter weight, smaller physical size, higher low end torque, wider power zone, cooler temperatures, and greater reliability with lower cost and significant environment benefit for the same peak output power compared to typically motors. A further discussion on the inherent redundancy of these motors for space applications will be provided.
6. Heat pumps; Synergy of high efficiency and low carbon electricity
Energy Technology Data Exchange (ETDEWEB)
Koike, Akio
2010-09-15
Heat pump is attracting wide attention for its high efficiency to utilize inexhaustible and renewable ambient heat in the environment. With its rapid innovation and efficiency improvement, this technology has a huge potential to reduce CO2 emissions by replacing currently widespread fossil fuel combustion systems to meet various heat demands from the residential, commercial and industrial sectors. Barriers to deployment such as low public awareness and a relatively long pay-back period do exist, so it is strongly recommended that each country implement policies to promote heat pumps as a renewable energy option and an effective method to combat global warming.
7. Development of large area, high efficiency amorphous silicon solar cell
Energy Technology Data Exchange (ETDEWEB)
Yoon, K.S.; Kim, S.; Kim, D.W. [Yu Kong Taedok Institute of Technology (Korea, Republic of)
1996-02-01
The objective of the research is to develop the mass-production technologies of high efficiency amorphous silicon solar cells in order to reduce the costs of solar cells and dissemination of solar cells. Amorphous silicon solar cell is the most promising option of thin film solar cells which are relatively easy to reduce the costs. The final goal of the research is to develop amorphous silicon solar cells having the efficiency of 10%, the ratio of light-induced degradation 15% in the area of 1200 cm{sup 2} and test the cells in the form of 2 Kw grid-connected photovoltaic system. (author) 35 refs., 8 tabs., 67 figs.
8. All passive architecture for high efficiency cascaded Raman conversion
Science.gov (United States)
Balaswamy, V.; Arun, S.; Chayran, G.; Supradeepa, V. R.
2018-02-01
Cascaded Raman fiber lasers have offered a convenient method to obtain scalable, high-power sources at various wavelength regions inaccessible with rare-earth doped fiber lasers. A limitation previously was the reduced efficiency of these lasers. Recently, new architectures have been proposed to enhance efficiency, but this came at the cost of enhanced complexity, requiring an additional low-power, cascaded Raman laser. In this work, we overcome this with a new, all-passive architecture for high-efficiency cascaded Raman conversion. We demonstrate our architecture with a fifth-order cascaded Raman converter from 1117nm to 1480nm with output power of ~64W and efficiency of 60%.
9. High efficiency USC power plant - present status and future potential
Energy Technology Data Exchange (ETDEWEB)
Blum, R. [Faelleskemikerne I/S Fynsvaerket (Denmark); Hald, J. [Elsam/Elkraft/TU Denmark (Denmark)
1998-12-31
Increasing demand for energy production with low impact on the environment and minimised fuel consumption can be met with high efficient coal fired power plants with advanced steam parameters. An important key to this improvement is the development of high temperature materials with optimised mechanical strength. Based on the results of more than ten years of development a coal fired power plant with an efficiency above 50 % can now be realised. Future developments focus on materials which enable an efficiency of 52-55 %. (orig.) 25 refs.
10. High-efficiency ventilated metamaterial absorber at low frequency
Science.gov (United States)
Wu, Xiaoxiao; Au-Yeung, Ka Yan; Li, Xin; Roberts, Robert Christopher; Tian, Jingxuan; Hu, Chuandeng; Huang, Yingzhou; Wang, Shuxia; Yang, Zhiyu; Wen, Weijia
2018-03-01
We demonstrate a ventilated metamaterial absorber operating at low frequency (90%) has been achieved in both simulations and experiments. This high-efficiency absorption under the ventilation condition originates from the weak coupling of two identical split tube resonators constituting the absorber, which leads to the hybridization of the degenerate eigenmodes and breaks the absorption upper limit of 50% for conventional transmissive symmetric acoustic absorbers. The absorber can also be extended to an array and work in free space. The absorber should have potential applications in acoustic engineering where both noise reduction and ventilation are required.
11. Polarization holograms allow highly efficient generation of complex light beams.
Science.gov (United States)
Ruiz, U; Pagliusi, P; Provenzano, C; Volke-Sepúlveda, K; Cipparrone, Gabriella
2013-03-25
We report a viable method to generate complex beams, such as the non-diffracting Bessel and Weber beams, which relies on the encoding of amplitude information, in addition to phase and polarization, using polarization holography. The holograms are recorded in polarization sensitive films by the interference of a reference plane wave with a tailored complex beam, having orthogonal circular polarizations. The high efficiency, the intrinsic achromaticity and the simplicity of use of the polarization holograms make them competitive with respect to existing methods and attractive for several applications. Theoretical analysis, based on the Jones formalism, and experimental results are shown.
12. High bandgap III-V alloys for high efficiency optoelectronics
Energy Technology Data Exchange (ETDEWEB)
Alberi, Kirstin; Mascarenhas, Angelo; Wanlass, Mark
2017-01-10
High bandgap alloys for high efficiency optoelectronics are disclosed. An exemplary optoelectronic device may include a substrate, at least one Al.sub.1-xIn.sub.xP layer, and a step-grade buffer between the substrate and at least one Al.sub.1-xIn.sub.xP layer. The buffer may begin with a layer that is substantially lattice matched to GaAs, and may then incrementally increase the lattice constant in each sequential layer until a predetermined lattice constant of Al.sub.1-xIn.sub.xP is reached.
13. High efficiency USC power plant - present status and future potential
Energy Technology Data Exchange (ETDEWEB)
Blum, R [Faelleskemikerne I/S Fynsvaerket (Denmark); Hald, J [Elsam/Elkraft/TU Denmark (Denmark)
1999-12-31
Increasing demand for energy production with low impact on the environment and minimised fuel consumption can be met with high efficient coal fired power plants with advanced steam parameters. An important key to this improvement is the development of high temperature materials with optimised mechanical strength. Based on the results of more than ten years of development a coal fired power plant with an efficiency above 50 % can now be realised. Future developments focus on materials which enable an efficiency of 52-55 %. (orig.) 25 refs.
14. High Efficient Bidirectional Battery Converter for residential PV Systems
DEFF Research Database (Denmark)
Pham, Cam; Kerekes, Tamas; Teodorescu, Remus
2012-01-01
Photovoltaic (PV) installation is suited for the residential environment and the generation pattern follows the distribution of residential power consumption in daylight hours. In the cases of unbalance between generation and demand, the Smart PV with its battery storage can absorb or inject...... the power to balance it. High efficient bidirectional converter for the battery storage is required due high system cost and because the power is processed twice. A 1.5kW prototype is designed and built with CoolMOS and SiC diodes, >;95% efficiency has been obtained with 200 kHz hard switching....
15. High Efficiency Power Converter for Low Voltage High Power Applications
DEFF Research Database (Denmark)
Nymand, Morten
The topic of this thesis is the design of high efficiency power electronic dc-to-dc converters for high-power, low-input-voltage to high-output-voltage applications. These converters are increasingly required for emerging sustainable energy systems such as fuel cell, battery or photo voltaic based......, and remote power generation for light towers, camper vans, boats, beacons, and buoys etc. A review of current state-of-the-art is presented. The best performing converters achieve moderately high peak efficiencies at high input voltage and medium power level. However, system dimensioning and cost are often...
16. Iodine laser of high efficiency and fast repetition rate
Energy Technology Data Exchange (ETDEWEB)
Hohla, K; Witte, K J
1976-07-01
The scaling laws of an iodine laser of high efficiency and fast repetition rate are reported. The laser is pumped with a new kind of low pressure Hg-UV-lamps which convert 32% of the electrical input in UV-light in the absorption band of the iodine laser and which can be fired up to 100 Hz. Details of a 10 kJ/1 nsec system as dimensions, energy density, repetition rate, flow velocity, gas composition and gas pressure and the overall efficiency are given which is expected to be about 2%.
17. The problems of high efficient extraction from the isochronous cyclotron
International Nuclear Information System (INIS)
Schwabe, J.
1994-06-01
The problem of high efficient extraction (η ≥ 50%) from isochronous cyclotrons (with the exception of the stripping method) is not completely solved up to this day. This problem is specifically important, because these cyclotrons are being also applied in the production of medical radioisotopes, labeled pharmaceuticals as well as in neutron therapy (oncology), machine industry, agriculture (plant mutagenesis), etc. The aim of the proposed topic is to solve this problem on the AIC-144 isochronous cyclotron in the INP (Institute of Nuclear Physics). Lately, a beam of 20 MeV deuterons with an efficiency of ca. 15% was extracted from this cyclotron. (author). 25 refs, 14 figs
18. Design of High Efficiency Illumination for LED Lighting
Directory of Open Access Journals (Sweden)
Yong-Nong Chang
2013-01-01
Full Text Available A high efficiency illumination for LED street lighting is proposed. For energy saving, this paper uses Class-E resonant inverter as main electric circuit to improve efficiency. In addition, single dimming control has the best efficiency, simplest control scheme and lowest circuit cost among other types of dimming techniques. Multiple serial-connected transformers used to drive the LED strings as they can provide galvanic isolation and have the advantage of good current distribution against device difference. Finally, a prototype circuit for driving 112 W LEDs in total was built and tested to verify the theoretical analysis.
19. High efficiency inductive output tubes with intense annular electron beams
Science.gov (United States)
Appanam Karakkad, J.; Matthew, D.; Ray, R.; Beaudoin, B. L.; Narayan, A.; Nusinovich, G. S.; Ting, A.; Antonsen, T. M.
2017-10-01
For mobile ionospheric heaters, it is necessary to develop highly efficient RF sources capable of delivering radiation in the frequency range from 3 to 10 MHz with an average power at a megawatt level. A promising source, which is capable of offering these parameters, is a grid-less version of the inductive output tube (IOT), also known as a klystrode. In this paper, studies analyzing the efficiency of grid-less IOTs are described. The basic trade-offs needed to reach high efficiency are investigated. In particular, the trade-off between the peak current and the duration of the current micro-pulse is analyzed. A particle in the cell code is used to self-consistently calculate the distribution in axial and transverse momentum and in total electron energy from the cathode to the collector. The efficiency of IOTs with collectors of various configurations is examined. It is shown that the efficiency of IOTs can be in the 90% range even without using depressed collectors.
20. High efficiency video coding coding tools and specification
CERN Document Server
Wien, Mathias
2015-01-01
The video coding standard High Efficiency Video Coding (HEVC) targets at improved compression performance for video resolutions of HD and beyond, providing Ultra HD video at similar compressed bit rates as for HD video encoded with the well-established video coding standard H.264 | AVC. Based on known concepts, new coding structures and improved coding tools have been developed and specified in HEVC. The standard is expected to be taken up easily by established industry as well as new endeavors, answering the needs of todays connected and ever-evolving online world. This book presents the High Efficiency Video Coding standard and explains it in a clear and coherent language. It provides a comprehensive and consistently written description, all of a piece. The book targets at both, newbies to video coding as well as experts in the field. While providing sections with introductory text for the beginner, it suits as a well-arranged reference book for the expert. The book provides a comprehensive reference for th...
1. Detecting Android Malwares with High-Efficient Hybrid Analyzing Methods
Directory of Open Access Journals (Sweden)
Yu Liu
2018-01-01
Full Text Available In order to tackle the security issues caused by malwares of Android OS, we proposed a high-efficient hybrid-detecting scheme for Android malwares. Our scheme employed different analyzing methods (static and dynamic methods to construct a flexible detecting scheme. In this paper, we proposed some detecting techniques such as Com+ feature based on traditional Permission and API call features to improve the performance of static detection. The collapsing issue of traditional function call graph-based malware detection was also avoided, as we adopted feature selection and clustering method to unify function call graph features of various dimensions into same dimension. In order to verify the performance of our scheme, we built an open-access malware dataset in our experiments. The experimental results showed that the suggested scheme achieved high malware-detecting accuracy, and the scheme could be used to establish Android malware-detecting cloud services, which can automatically adopt high-efficiency analyzing methods according to the properties of the Android applications.
2. Highly Efficient Thermoresponsive Nanocomposite for Controlled Release Applications
KAUST Repository
Yassine, Omar
2016-06-23
Highly efficient magnetic release from nanocomposite microparticles is shown, which are made of Poly (N-isopropylacrylamide) hydrogel with embedded iron nanowires. A simple microfluidic technique was adopted to fabricate the microparticles with a high control of the nanowire concentration and in a relatively short time compared to chemical synthesis methods. The thermoresponsive microparticles were used for the remotely triggered release of Rhodamine (B). With a magnetic field of only 1 mT and 20 kHz a drug release of 6.5% and 70% was achieved in the continuous and pulsatile modes, respectively. Those release values are similar to the ones commonly obtained using superparamagnetic beads but accomplished with a magnetic field of five orders of magnitude lower power. The high efficiency is a result of the high remanent magnetization of the nanowires, which produce a large torque when exposed to a magnetic field. This causes the nanowires to vibrate, resulting in friction losses and heating. For comparison, microparticles with superparamagnetic beads were also fabricated and tested; while those worked at 73 mT and 600 kHz, no release was observed at the low field conditions. Cytotoxicity assays showed similar and high cell viability for microparticles with nanowires and beads.
3. Highly Efficient Thermoresponsive Nanocomposite for Controlled Release Applications
KAUST Repository
Yassine, Omar; Zaher, Amir; Li, Erqiang; Alfadhel, Ahmed; Perez, Jose E.; Kavaldzhiev, Mincho; Contreras, Maria F.; Thoroddsen, Sigurdur T; Khashab, Niveen M.; Kosel, Jü rgen
2016-01-01
Highly efficient magnetic release from nanocomposite microparticles is shown, which are made of Poly (N-isopropylacrylamide) hydrogel with embedded iron nanowires. A simple microfluidic technique was adopted to fabricate the microparticles with a high control of the nanowire concentration and in a relatively short time compared to chemical synthesis methods. The thermoresponsive microparticles were used for the remotely triggered release of Rhodamine (B). With a magnetic field of only 1 mT and 20 kHz a drug release of 6.5% and 70% was achieved in the continuous and pulsatile modes, respectively. Those release values are similar to the ones commonly obtained using superparamagnetic beads but accomplished with a magnetic field of five orders of magnitude lower power. The high efficiency is a result of the high remanent magnetization of the nanowires, which produce a large torque when exposed to a magnetic field. This causes the nanowires to vibrate, resulting in friction losses and heating. For comparison, microparticles with superparamagnetic beads were also fabricated and tested; while those worked at 73 mT and 600 kHz, no release was observed at the low field conditions. Cytotoxicity assays showed similar and high cell viability for microparticles with nanowires and beads.
4. Large-area high-efficiency flexible PHOLED lighting panels
Science.gov (United States)
Pang, Huiqing; Mandlik, Prashant; Levermore, Peter A.; Silvernail, Jeff; Ma, Ruiqing; Brown, Julie J.
2012-09-01
Organic Light Emitting Diodes (OLEDs) provide various attractive features for next generation illumination systems, including high efficiency, low power, thin and flexible form factor. In this work, we incorporated phosphorescent emitters and demonstrated highly efficient white phosphorescent OLED (PHOLED) devices on flexible plastic substrates. The 0.94 cm2 small-area device has total thickness of approximately 0.25 mm and achieved 63 lm/W at 1,000 cd/m2 with CRI = 85 and CCT = 2920 K. We further designed and fabricated a 15 cm x 15 cm large-area flexible white OLED lighting panels, finished with a hybrid single-layer ultra-low permeability single layer barrier (SLB) encapsulation film. The flexible panel has an active area of 116.4 cm2, and achieved a power efficacy of 47 lm/W at 1,000 cd/m2 with CRI = 83 and CCT = 3470 K. The efficacy of the panel at 3,000 cd/m2 is 43 lm/W. The large-area flexible PHOLED lighting panel is to bring out enormous possibilities to the future general lighting applications.
5. Advanced Passivation Technology and Loss Factor Minimization for High Efficiency Solar Cells.
Science.gov (United States)
Park, Cheolmin; Balaji, Nagarajan; Jung, Sungwook; Choi, Jaewoo; Ju, Minkyu; Lee, Seunghwan; Kim, Jungmo; Bong, Sungjae; Chung, Sungyoun; Lee, Youn-Jung; Yi, Junsin
2015-10-01
High-efficiency Si solar cells have attracted great attention from researchers, scientists, photovoltaic (PV) industry engineers for the past few decades. With thin wafers, surface passivation becomes necessary to increase the solar cells efficiency by overcoming several induced effects due to associated crystal defects and impurities of c-Si. This paper discusses suitable passivation schemes and optimization techniques to achieve high efficiency at low cost. SiNx film was optimized with higher transmittance and reduced recombination for using as an effective antireflection and passivation layer to attain higher solar cell efficiencies. The higher band gap increased the transmittance with reduced defect states that persisted at 1.68 and 1.80 eV in SiNx films. The thermal stability of SiN (Si-rich)/SiN (N-rich) stacks was also studied. Si-rich SiN with a refractive index of 2.7 was used as a passivation layer and N-rich SiN with a refractive index of 2.1 was used for thermal stability. An implied Voc of 720 mV with a stable lifetime of 1.5 ms was obtained for the stack layer after firing. Si-N and Si-H bonding concentration was analyzed by FTIR for the correlation of thermally stable passivation mechanism. The passivation property of spin coated Al2O3 films was also investigated. An effective surface recombination velocity of 55 cm/s with a high density of negative fixed charges (Qf) on the order of 9 x 10(11) cm(-2) was detected in Al2O3 films.
6. Microbial electrolytic disinfection process for highly efficient Escherichia coli inactivation
DEFF Research Database (Denmark)
Zhou, Shaofeng; Huang, Shaobin; Li, Xiaohu
2018-01-01
extensively studied for recalcitrant organics removal, its application potential towards water disinfection (e.g., inactivation of pathogens) is still unknown. This study investigated the inactivation of Escherichia coli in a microbial electrolysis cell based bio-electro-Fenton system (renamed as microbial......Water quality deterioration caused by a wide variety of recalcitrant organics and pathogenic microorganisms has become a serious concern worldwide. Bio-electro-Fenton systems have been considered as cost-effective and highly efficient water treatment platform technology. While it has been......]OH was identified as one potential mechanism for disinfection. This study successfully demonstrated the feasibility of bio-electro-Fenton process for pathogens inactivation, which offers insight for the future development of sustainable, efficient, and cost-effective biological water treatment technology....
7. Highly efficient light management for perovskite solar cells.
Science.gov (United States)
Wang, Dong-Lin; Cui, Hui-Juan; Hou, Guo-Jiao; Zhu, Zhen-Gang; Yan, Qing-Bo; Su, Gang
2016-01-06
Organic-inorganic halide perovskite solar cells have enormous potential to impact the existing photovoltaic industry. As realizing a higher conversion efficiency of the solar cell is still the most crucial task, a great number of schemes were proposed to minimize the carrier loss by optimizing the electrical properties of the perovskite solar cells. Here, we focus on another significant aspect that is to minimize the light loss by optimizing the light management to gain a high efficiency for perovskite solar cells. In our scheme, the slotted and inverted prism structured SiO2 layers are adopted to trap more light into the solar cells, and a better transparent conducting oxide layer is employed to reduce the parasitic absorption. For such an implementation, the efficiency and the serviceable angle of the perovskite solar cell can be promoted impressively. This proposal would shed new light on developing the high-performance perovskite solar cells.
8. High efficiency heat transport and power conversion system for cascade
International Nuclear Information System (INIS)
Maya, I.; Bourque, R.F.; Creedon, R.L.; Schultz, K.R.
1985-02-01
The Cascade ICF reactor features a flowing blanket of solid BeO and LiAlO 2 granules with very high temperature capability (up to approx. 2300 K). The authors present here the design of a high temperature granule transport and heat exchange system, and two options for high efficiency power conversion. The centrifugal-throw transport system uses the peripheral speed imparted to the granules by the rotating chamber to effect granule transport and requires no additional equipment. The heat exchanger design is a vacuum heat transfer concept utilizing gravity-induced flow of the granules over ceramic heat exchange surfaces. A reference Brayton power cycle is presented which achieves 55% net efficiency with 1300 K peak helium temperature. A modified Field steam cycle (a hybrid Rankine/Brayton cycle) is presented as an alternate which achieves 56% net efficiency
9. Improved entropy encoding for high efficient video coding standard
Directory of Open Access Journals (Sweden)
B.S. Sunil Kumar
2018-03-01
Full Text Available The High Efficiency Video Coding (HEVC has better coding efficiency, but the encoding performance has to be improved to meet the growing multimedia applications. This paper improves the standard entropy encoding by introducing the optimized weighing parameters, so that higher rate of compression can be accomplished over the standard entropy encoding. The optimization is performed using the recently introduced firefly algorithm. The experimentation is carried out using eight benchmark video sequences and the PSNR for varying rate of data transmission is investigated. Comparative analysis based on the performance statistics is made with the standard entropy encoding. From the obtained results, it is clear that the originality of the decoded video sequence is preserved far better than the proposed method, though the compression rate is increased. Keywords: Entropy, Encoding, HEVC, PSNR, Compression
10. Simple processing of high efficiency silicon solar cells
International Nuclear Information System (INIS)
Hamammu, I.M.; Ibrahim, K.
2006-01-01
Cost effective photovoltaic devices have been an area research since the development of the first solar cells, as cost is the major factor in their usage. Silicon solar cells have the biggest share in the photovoltaic market, though silicon os not the optimal material for solar cells. This work introduces a simplified approach for high efficiency silicon solar cell processing, by minimizing the processing steps and thereby reducing cost. The suggested procedure might also allow for the usage of lower quality materials compared to the one used today. The main features of the present work fall into: simplifying the diffusion process, edge shunt isolation and using acidic texturing instead of the standard alkaline processing. Solar cells of 17% efficiency have been produced using this procedure. Investigations on the possibility of improving the efficiency and using less quality material are still underway
11. Highly Efficient Coherent Optical Memory Based on Electromagnetically Induced Transparency
Science.gov (United States)
Hsiao, Ya-Fen; Tsai, Pin-Ju; Chen, Hung-Shiue; Lin, Sheng-Xiang; Hung, Chih-Chiao; Lee, Chih-Hsi; Chen, Yi-Hsin; Chen, Yong-Fan; Yu, Ite A.; Chen, Ying-Cheng
2018-05-01
Quantum memory is an important component in the long-distance quantum communication based on the quantum repeater protocol. To outperform the direct transmission of photons with quantum repeaters, it is crucial to develop quantum memories with high fidelity, high efficiency and a long storage time. Here, we achieve a storage efficiency of 92.0 (1.5)% for a coherent optical memory based on the electromagnetically induced transparency scheme in optically dense cold atomic media. We also obtain a useful time-bandwidth product of 1200, considering only storage where the retrieval efficiency remains above 50%. Both are the best record to date in all kinds of schemes for the realization of optical memory. Our work significantly advances the pursuit of a high-performance optical memory and should have important applications in quantum information science.
12. A Low VSWR and High Efficiency Waveguide Feed Antenna Array
Directory of Open Access Journals (Sweden)
Zhao Xiao-Fang
2018-01-01
Full Text Available A low VSWR and high efficiency antenna array operating in the Ku band for satellite communications is presented in this paper. To achieve high radiation efficiency and broad enough bandwidth, all-metal radiation elements and full-corporate waveguide feeding network are employed. As the general milling method is used in the multilayer antenna array fabrication, the E-plane waveguide feeding network is adopted here to suppress the wave leakage caused by the imperfect connectivity between adjacent layers. A 4 × 8 elements array prototype was fabricated and tested for verification. The measured results of proposed antenna array show bandwidth of 6.9% (13.9–14.8 GHz for VSWR < 1.5. Furthermore, antenna gain and efficiency of higher than 22.2 dBi and 80% are also exhibited, respectively.
13. Rigid-beam model of a high-efficiency magnicon
International Nuclear Information System (INIS)
Rees, D.E.; Tallerico, P.J.; Humphries, S.J. Jr.
1993-01-01
The magnicon is a new type of high-efficiency deflection-modulated amplifier developed at the Institute of Nuclear Physics in Novosibirsk, Russia. The prototype pulsed magnicon achieved an output power of 2.4 MW and an efficiency of 73% at 915 MHz. This paper presents the results of a rigid-beam model for a 700-MHz, 2.5-MW 82%-efficient magnicon. The rigid-beam model allows for characterization of the beam dynamics by tracking only a single electron. The magnicon design presented consists of a drive cavity; passive cavities; a pi-mode, coupled-deflection cavity; and an output cavity. It represents an optimized design. The model is fully self-consistent, and this paper presents the details of the model and calculated performance of a 2.5-MW magnicon
14. Disposal of aqueous condensate from high efficiency gas boilers
Energy Technology Data Exchange (ETDEWEB)
Hardwick, G J; Pattison, J R
1984-01-01
If highly efficient gas-fired condensing heating appliances are installed in Britain, the aqueous condensate produced can be conveniently run into existing sewage drains. The part of the drainage system that is most vulnerable to corrosion from the mildly acid condensate is that portion adjacent to the domestic premises. The tests described indicate that this is not at risk and the only precaution that might be considered necessary is to avoid running the condensate over galvanized drain covers in order to prevent unsightly staining. Water authorities in Britain and detailed studies in the US and Holland confirm that the condensate - after dilution by domestic waste, sewage, and rainwater - would be harmless to municipal sewage systems and would not, either in volume or chemical composition, affect the working of existing sewage treatment plants.
15. Study on a Novel High-Efficiency Bridgeless PFC Converter
Directory of Open Access Journals (Sweden)
Cao Taiqiang
2014-01-01
Full Text Available In order to implement a high-efficiency bridgeless power factor correction converter, a new topology and operation principles of continuous conduction mode (CCM and DC steady-state character of the converter are analyzed, which show that the converter not only has bipolar-gain characteristic but also has the same characteristic as the traditional Boost converter, while the voltage transfer ratio is not related with the resonant branch parameters and switching frequency. Based on the above topology, a novel bridgeless Bipolar-Gain Pseudo-Boost PFC converter is proposed. With this converter, the diode rectifier bridge of traditional AC-DC converter is eliminated, and zero-current switching of fast recovery diode is achieved. Thus, the efficiency is improved. Next, we also propose the one-cycle control policy of this converter. Finally, experiments are provided to verify the accuracy and feasibility of the proposed converter.
16. High efficiency particulate removal with sintered metal filters
International Nuclear Information System (INIS)
Kirstein, B.E.; Paplawsky, W.J.; Pence, D.T.; Hedahl, T.G.
1981-01-01
Because of their particle removal efficiencies and durability, sintered metal filters have been chosen for high efficiency particulate air (HEPA) filter protection in the off-gas treatment system for the proposed Idaho National Engineering Laboratory Transuranic Waste Treatment Facility. Process evaluation of sintered metal filters indicated a lack of sufficient process design data to ensure trouble-free operation. Subsequence pilot scale testing was performed with flyash as the test particulate. The test results showed that the sintered metal filters can have an efficiency greater than 0.9999999 for the specific test conditions used. Stable pressure drop characteristics were observed in pulsed and reversed flow blowback modes of operation. Over 4900 hours of operation were obtained with operating conditions ranging up to approximately 90 0 C and 24 vol % water vapor in the gas stream
17. Highly Efficient Catalytic Cyclic Carbonate Formation by Pyridyl Salicylimines.
Science.gov (United States)
Subramanian, Saravanan; Park, Joonho; Byun, Jeehye; Jung, Yousung; Yavuz, Cafer T
2018-03-21
Cyclic carbonates as industrial commodities offer a viable nonredox carbon dioxide fixation, and suitable heterogeneous catalysts are vital for their widespread implementation. Here, we report a highly efficient heterogeneous catalyst for CO 2 addition to epoxides based on a newly identified active catalytic pocket consisting of pyridine, imine, and phenol moieties. The polymeric, metal-free catalyst derived from this active site converts less-reactive styrene oxide under atmospheric pressure in quantitative yield and selectivity to the corresponding carbonate. The catalyst does not need additives, solvents, metals, or co-catalysts, can be reused at least 10 cycles without the loss of activity, and scaled up easily to a kilogram scale. Density functional theory calculations reveal that the nucleophilicity of pyridine base gets stronger due to the conjugated imines and H-bonding from phenol accelerates the reaction forward by stabilizing the intermediate.
18. Development and evaluation of a cleanable high efficiency steel filter
International Nuclear Information System (INIS)
Bergman, W.; Larsen, G.; Weber, F.; Wilson, P.; Lopez, R.; Valha, G.; Conner, J.; Garr, J.; Williams, K.; Biermann, A.; Wilson, K.; Moore, P.; Gellner, C.; Rapchun, D.; Simon, K.; Turley, J.; Frye, L.; Monroe, D.
1993-01-01
We have developed a high efficiency steel filter that can be cleaned in-situ by reverse air pulses. The filter consists of 64 pleated cylindrical filter elements packaged into a 6l0 x 6l0 x 292 mm aluminum frame and has 13.5 m 2 of filter area. The filter media consists of a sintered steel fiber mat using 2 μm diameter fibers. We conducted an optimization study for filter efficiency and pressure drop to determine the filter design parameters of pleat width, pleat depth, outside diameter of the cylinder, and the total number of cylinders. Several prototype cylinders were then built and evaluated in terms of filter cleaning by reverse air pulses. The results of these studies were used to build the high efficiency steel filter. We evaluated the prototype filter for efficiency and cleanability. The DOP filter certification test showed the filter has a passing efficiency of 99.99% but a failing pressure drop of 0.80 kPa at 1,700 m 3 /hr. Since we were not able to achieve a pressure drop less than 0.25 kPa, the steel filter does not meet all the criteria for a HEPA filter. Filter loading and cleaning tests using AC Fine dust showed the filter could be repeatedly cleaned by reverse air pulses. The next phase of the prototype evaluation consisted of installing the unit and support housing in the exhaust duct work of a uranium grit blaster for a field evaluation at the Y-12 Plant in Oak Ridge, TN. The grit blaster is used to clean the surface of uranium parts and generates a cloud of UO 2 aerosols. We used a 1,700 m 3 /hr slip stream from the 10,200 m 3 /hr exhaust system
19. Comparison of high efficiency particulate filter testing methods
International Nuclear Information System (INIS)
1985-01-01
High Efficiency Particulate Air (HEPA) filters are used for the removal of submicron size particulates from air streams. In nuclear industry they are used as an important engineering safeguard to prevent the release of air borne radioactive particulates to the environment. HEPA filters used in the nuclear industry should therefore be manufactured and operated under strict quality control. There are three levels of testing HEPA filters: i) testing of the filter media; ii) testing of the assembled filter including filter media and filter housing; and iii) on site testing of the complete filter installation before putting into operation and later for the purpose of periodic control. A co-ordinated research programme on particulate filter testing methods was taken up by the Agency and contracts were awarded to the Member Countries, Belgium, German Democratic Republic, India and Hungary. The investigations carried out by the participants of the present co-ordinated research programme include the results of the nowadays most frequently used HEPA filter testing methods both for filter medium test, rig test and in-situ test purposes. Most of the experiments were carried out at ambient temperature and humidity, but indications were given to extend the investigations to elevated temperature and humidity in the future for the purpose of testing the performance of HEPA filter under severe conditions. A major conclusion of the co-ordinated research programme was that it was not possible to recommend one method as a reference method for in situ testing of high efficiency particulate air filters. Most of the present conventional methods are adequate for current requirements. The reasons why no method is to be recommended were multiple, ranging from economical aspects, through incompatibility of materials to national regulations
20. Preliminary field evaluation of high efficiency steel filters
Energy Technology Data Exchange (ETDEWEB)
Bergman, W.; Larsen, G.; Lopez, R. [Lawrence Livermore National Laboratory, CA (United States)] [and others
1995-02-01
We have conducted an evaluation of two high efficiency steel filters in the exhaust of an uranium oxide grit blaster at the Y-12 Plant in Oak Ridge Tennessee. The filters were installed in a specially designed filter housing with a reverse air-pulse cleaning system for automatically cleaning the filters in-place. Previous tests conducted on the same filters and housing at LLNL under controlled conditions using Arizona road dust showed good cleanability with reverse air pulses. Two high efficiency steel filters, containing 64 pleated cartridge elements housed in the standard 2 x 2 x 1 HEPA frame, were evaluated in the filter test housing using a 1,000 cfm slip stream containing a high concentration of depleted uranium oxide dust. One filter had the pleated cartridges manufactured to our specifications by the Pall Corporation and the other by Memtec Corporation. Test results showed both filters had a rapid increase in pressure drop with time, and reverse air pulses could not decrease the pressure drop. We suspected moisture accumulation in the filters was the problem since there were heavy rains during the evaluations, and the pressure drop of the Memtec filter decreased dramatically after passing clean, dry air through the filter and after the filter sat idle for one week. Subsequent laboratory tests on a single filter cartridge confirmed that water accumulation in the filter was responsible for the increase in filter pressure drop and the inability to lower the pressure drop by reverse air pulses. No effort was made to identify the source of the water accumulation and correct the problem because the available funds were exhausted.
1. A new approach to a high efficiency inductive store
International Nuclear Information System (INIS)
Zowarka, R.C. Jr.; Kajs, J.P.; Price, J.H.; Weldon, W.F.
1991-01-01
In the Spring of 1989, Parker Kinetic Design, Inc. (PKD) and the Center for Electromechanics at The University of Texas at Austin (CEM-UT) conducted a study to examine the basic technologies to be used in the construction and operation of a feasible and reliable electromagnetic (EM) gun system. This work was performed for Brown and Root Vickers, Ltd. (BRV) in response to a feasibility analysis requirement of the Royal Armament and Development Establishment (RARDE), Ministry of Defence (MD) of the United Kingdom. This paper summarizes that this study focused on the analysis and evaluation of the suitability and applicability of various pulsed power supply options for the performance goals of the RARDE EM gun program. The existing technologies considered included batteries, compulsators, capacitors, and homopolar generators (HPGs). Primary performance specifications for the electrical energy radius system were that it be capable of providing 12 MJ of muzzle energy; velocities between 2.0 and 3.5 km/s; and a repetitive shot rate of up to 10 shots per day, with no more than a 30-min interval between shots. In addition, the recommended system needed to be reliable, easily maintainable, and capable of routinely firing large numbers of shots. Strict adherence to the goal of designing a system based only on demonstrated technology results in power supplies that are prohibitively expensive and large. As a consequence, candidate system designs represent a modest extrapolation from demonstrated technology well within an acceptable design envelope. A new topology has been developed for a highly efficient inductive store suitable for pulsed-power applications. The new design features high L/R ratios without having to cryogenically cool the conductors. This allows for high efficiency charging of the inductor from low impedance dc sources such as batteries of HPGs
2. Behavior and monitoring of air filters of high efficiency during fire
International Nuclear Information System (INIS)
Chappellier, Andre; Chappellier, Simonne.
1980-07-01
High efficiency filters were submitted to dynamic tests at graduated temperatures. As compared to the case of fire taking place in a high activity building equiped with such purifying system, these tests can be considered as significant. The tested filters were found out to resist to three ranges of temperatures: (1) 130 0 C during one hour, (ii) 250 0 C during one hour, (iii) 400 0 C during at least two hours. Some observed phenomenons, as for instance, the smoke emission due to glues, or building materials pyrolysis will progress the conception doctrine of fire detection network in ventilation sheath. Moreover these tests demonstrated that thermal fire detectors well chosen and correctly put into operation can be useful in these sheaths [fr
3. Fused Methoxynaphthyl Phenanthrimidazole Semiconductors as Functional Layer in High Efficient OLEDs.
Science.gov (United States)
Jayabharathi, Jayaraman; Ramanathan, Periyasamy; Karunakaran, Chockalingam; Thanikachalam, Venugopal
2016-01-01
Efficient hole transport materials based on novel fused methoxynaphthyl phenanthrimidazole core structure were synthesised and characterized. Their device performances in phosphorescent organic light emitting diodes were investigated. The high thermal stability in combination with the reversible oxidation process made promising candidates as hole-transporting materials for organic light-emitting devices. Highly efficient Alq3-based organic light emitting devices have been developed using phenanthrimidazoles as functional layers between NPB [4,4-bis(N-(1-naphthyl)-N-phenylamino)biphenyl] and Alq3 [tris(8-hydroxyquinoline)aluminium] layers. Using the device of ITO/NPB/4/Alq3/LiF/Al, a maximum luminous efficiency of 5.99 cd A(-1) was obtained with a maximum brightness of 40,623 cd m(-2) and a power efficiency of 5.25 lm W(-1).
4. Photo-degradation of high efficiency fullerene-free polymer solar cells.
Science.gov (United States)
Upama, Mushfika Baishakhi; Wright, Matthew; Mahmud, Md Arafat; Elumalai, Naveen Kumar; Mahboubi Soufiani, Arman; Wang, Dian; Xu, Cheng; Uddin, Ashraf
2017-12-07
Polymer solar cells are a promising technology for the commercialization of low cost, large scale organic solar cells. With the evolution of high efficiency (>13%) non-fullerene polymer solar cells, the stability of the cells has become a crucial parameter to be considered. Among the several degradation mechanisms of polymer solar cells, burn-in photo-degradation is relatively less studied. Herein, we present the first systematic study of photo-degradation of novel PBDB-T:ITIC fullerene-free polymer solar cells. The thermally treated and as-prepared PBDB-T:ITIC solar cells were exposed to continuous 1 sun illumination for 5 hours. The aged devices exhibited rapid losses in the short-circuit current density and fill factor. The severe short-circuit current and fill factor burn in losses were attributed to trap mediated charge recombination, as evidenced by an increase in Urbach energy for aged devices.
5. Numerical quantification and minimization of perimeter losses in high-efficiency silicon solar cells
Energy Technology Data Exchange (ETDEWEB)
Altermatt, P.P.; Heiser, Gernot; Green, M.A. [New South Wales Univ., Kensington, NSW (Australia)
1996-09-01
This paper presents a quantitative analysis of perimeter losses in high-efficiency silicon solar cells. A new method of numerical modelling is used, which provides the means to simulate a full-sized solar cell, including its perimeter region. We analyse the reduction in efficiency due to perimeter losses as a function of the distance between the active cell area and the cut edge. It is shown how the optimum distance depends on whether the cells in the panel are shingled or not. The simulations also indicate that passivating the cut-face with a thermal oxide does not increase cell efficiency substantially. Therefore, doping schemes for the perimeter domain are suggested in order to increase efficiency levels above present standards. Finally, perimeter effects in cells that remain embedded in the wafer during the efficiency measurement are outlined. (author)
6. Highly efficient transparent Zn2SiO4:Mn2+ phosphor film on quartz glass
International Nuclear Information System (INIS)
Seo, K.I.; Park, J.H.; Kim, J.S.; Kim, G.C.; Yoo, J.H.
2009-01-01
Highly efficient transparent Zn 2 SiO 4 :Mn 2+ film phosphors on quartz substrates were deposited by the thermal diffusion of sputtered ZnO:Mn film. They show a textured structure with some preferred orientations. Our film phosphor shows, for the best photoluminescence (PL) brightness, a green PL brightness of about 20% of a commercial Zn 2 SiO 4 :Mn 2+ powder phosphor screen. The film shows a high transmittance of more than 10% at the red-color region. The excellence in PL brightness and transmittance can be explained in terms of the textured crystal growth with a continuous gradient of Zn 2 SiO 4 : Mn 2+ crystals.
7. Industrial PVD metallization for high efficiency crystalline silicon solar cells
OpenAIRE
Nekarda, J.; Reinwand, D.; Grohe, A.; Hartmann, P.; Preu, R.; Trassl, R.; Wieder, S.
2009-01-01
In this paper we present first results concerning different thermal evaporation processes for thin aluminum layers, which are carried out on a pilot system with a throughput of up to 540 wafers/h (156x156 mm2). To qualify the processes the deposited aluminum layers were evaluated with respect to homogeneity and conductivity. Additionally the effect of the different processes on the passivation quality of a thermally grown 100 nm thick SiO 2 was analyzed by means of lifetime measurements, indi...
8. Second Generation Advanced Reburning for High Efficiency NOx Control
International Nuclear Information System (INIS)
Zamansky, Vladimir M.; Maly, Peter M.; Sheldon, Mark; Seeker, W. Randall; Folsom, Blair A.
1997-01-01
Energy and Environmental Research Corporation is developing a family of high efficiency and low cost NO x control technologies for coal fired utility boilers based on Advanced Reburning (AR), a synergistic integration of basic reburning with injection of an N-agent. In conventional AR, injection of the reburn fuel is followed by simultaneous N-agent and overfire air injection. The second generation AR systems incorporate several components which can be used in different combinations. These components include: (1) Reburning Injection of the reburn fuel and overfire air. (2) N-agent Injection The N-agent (ammonia or urea) can be injected at different locations: into the reburning zone, along with the overfire air, and downstream of the overfire air injection. (3) N-agent Promotion Several sodium compounds can considerably enhance the NO x control from N-agent injection. These ''promoters'' can be added to aqueous N-agents. (4) Two Stages of N-agent Injection and Promotion Two N-agents with or without promoters can be injected at different locations for deeper NO x control. AR systems are intended for post-RACT applications in ozone non-attainment areas where NO x control in excess of 80% is required. AR will provide flexible installations that allow NO x levels to be lowered when regulations become more stringent. The total cost of NO x control for AR systems is approximately half of that for SCR. Experimental and kinetic modeling results for development of these novel AR systems are presented. Tests have been conducted in a 1.0 MMBtu/hr Boiler Simulator Facility with coal as the main fuel and natural gas as the reburning fuel. The results show that high efficiency NO x control, in the range 84-95%, can be achieved with various elements of AR. A comparative byproduct emission study was performed to compare the emissions from different variants of AR with commercial technologies (reburning and SNCR). For each technology sampling included: CO, SO 2 , N 2 O, total
9. In-situ high efficiency filter testing at AEE Winfrith
International Nuclear Information System (INIS)
Fraser, D.C.
1977-01-01
This paper discusses experience in the testing of high efficiency filters in a variety of reactor and plant installations at AEE Winfrith. There is rarely any concern about the effectiveness of the filter as supplied by any reputable manufacturer. Experience has shown there is a need to check for defects in the installation of filters which could lead to by-passing of aerosols and it is desirable to perform periodical re-tests to ensure that no subsequent deterioration occurs. It is important to use simple, portable apparatus for such tests; methods based on the use of sodium chloride aerosols, although suitable for the testing of filters prior to installation, involve apparatus which is too bulky for in-situ testing. At Winfrith a double automatic Pollak counter has been developed and used routinely since 1970. The aerosol involved has a particle size far smaller than the size most likely to penetrate intact filters, but this is irrelevant when one is primarily interested in particles which by-pass the filter. Comparisons with other methods of testing filters will be described. There is remarkably good agreement between the efficiency of the filter installation as measured by a Pollak counter compared with techniques involving aerosols of sodium chloride and Dioctyl Phthalate (DOP), presumably because the leakage around the filter is independent of particle size
10. Highly Efficient and Reproducible Nonfullerene Solar Cells from Hydrocarbon Solvents
KAUST Repository
Wadsworth, Andrew; Ashraf, Raja; Abdelsamie, Maged; Pont, Sebastian; Little, Mark; Moser, Maximilian; Hamid, Zeinab; Neophytou, Marios; Zhang, Weimin; Amassian, Aram; Durrant, James R.; Baran, Derya; McCulloch, Iain
2017-01-01
With chlorinated solvents unlikely to be permitted for use in solution-processed organic solar cells in industry, there must be a focus on developing nonchlorinated solvent systems. Here we report high-efficiency devices utilizing a low-bandgap donor polymer (PffBT4T-2DT) and a nonfullerene acceptor (EH-IDTBR) from hydrocarbon solvents and without using additives. When mesitylene was used as the solvent, rather than chlorobenzene, an improved power conversion efficiency (11.1%) was achieved without the need for pre- or post-treatments. Despite altering the processing conditions to environmentally friendly solvents and room-temperature coating, grazing incident X-ray measurements confirmed that active layers processed from hydrocarbon solvents retained the robust nanomorphology obtained with hot-processed chlorinated solvents. The main advantages of hydrocarbon solvent-processed devices, besides the improved efficiencies, were the reproducibility and storage lifetime of devices. Mesitylene devices showed better reproducibility and shelf life up to 4000 h with PCE dropping by only 8% of its initial value.
11. A high efficiency hybrid stirling-pulse tube cryocooler
Directory of Open Access Journals (Sweden)
Xiaotao Wang
2015-03-01
Full Text Available This article presented a hybrid cryocooler which combines the room temperature displacers and the pulse tube in one system. Compared with a traditional pulse tube cryocooler, the system uses the rod-less ambient displacer to recover the expansion work from the pulse tube cold end to improve the efficiency while still keeps the advantage of the pulse tube cryocooler with no moving parts at the cold region. In the meantime, dual-opposed configurations for both the compression pistons and displacers reduce the cooler vibration to a very low level. In the experiments, a lowest no-load temperature of 38.5 K has been obtained and the cooling power at 80K was 26.4 W with an input electric power of 290 W. This leads to an efficiency of 24.2% of Carnot, marginally higher than that of an ordinary pulse tube cryocooler. The hybrid configuration herein provides a very competitive option when a high efficiency, high-reliability and robust cryocooler is desired.
12. MXene molecular sieving membranes for highly efficient gas separation.
Science.gov (United States)
Ding, Li; Wei, Yanying; Li, Libo; Zhang, Tao; Wang, Haihui; Xue, Jian; Ding, Liang-Xin; Wang, Suqing; Caro, Jürgen; Gogotsi, Yury
2018-01-11
Molecular sieving membranes with sufficient and uniform nanochannels that break the permeability-selectivity trade-off are desirable for energy-efficient gas separation, and the arising two-dimensional (2D) materials provide new routes for membrane development. However, for 2D lamellar membranes, disordered interlayer nanochannels for mass transport are usually formed between randomly stacked neighboring nanosheets, which is obstructive for highly efficient separation. Therefore, manufacturing lamellar membranes with highly ordered nanochannel structures for fast and precise molecular sieving is still challenging. Here, we report on lamellar stacked MXene membranes with aligned and regular subnanometer channels, taking advantage of the abundant surface-terminating groups on the MXene nanosheets, which exhibit excellent gas separation performance with H 2 permeability >2200 Barrer and H 2 /CO 2 selectivity >160, superior to the state-of-the-art membranes. The results of molecular dynamics simulations quantitatively support the experiments, confirming the subnanometer interlayer spacing between the neighboring MXene nanosheets as molecular sieving channels for gas separation.
13. High-Efficient Parallel CAVLC Encoders on Heterogeneous Multicore Architectures
Directory of Open Access Journals (Sweden)
H. Y. Su
2012-04-01
Full Text Available This article presents two high-efficient parallel realizations of the context-based adaptive variable length coding (CAVLC based on heterogeneous multicore processors. By optimizing the architecture of the CAVLC encoder, three kinds of dependences are eliminated or weaken, including the context-based data dependence, the memory accessing dependence and the control dependence. The CAVLC pipeline is divided into three stages: two scans, coding, and lag packing, and be implemented on two typical heterogeneous multicore architectures. One is a block-based SIMD parallel CAVLC encoder on multicore stream processor STORM. The other is a component-oriented SIMT parallel encoder on massively parallel architecture GPU. Both of them exploited rich data-level parallelism. Experiments results show that compared with the CPU version, more than 70 times of speedup can be obtained for STORM and over 50 times for GPU. The implementation of encoder on STORM can make a real-time processing for 1080p @30fps and GPU-based version can satisfy the requirements for 720p real-time encoding. The throughput of the presented CAVLC encoders is more than 10 times higher than that of published software encoders on DSP and multicore platforms.
14. Novel Intermode Prediction Algorithm for High Efficiency Video Coding Encoder
Directory of Open Access Journals (Sweden)
Chan-seob Park
2014-01-01
Full Text Available The joint collaborative team on video coding (JCT-VC is developing the next-generation video coding standard which is called high efficiency video coding (HEVC. In the HEVC, there are three units in block structure: coding unit (CU, prediction unit (PU, and transform unit (TU. The CU is the basic unit of region splitting like macroblock (MB. Each CU performs recursive splitting into four blocks with equal size, starting from the tree block. In this paper, we propose a fast CU depth decision algorithm for HEVC technology to reduce its computational complexity. In 2N×2N PU, the proposed method compares the rate-distortion (RD cost and determines the depth using the compared information. Moreover, in order to speed up the encoding time, the efficient merge SKIP detection method is developed additionally based on the contextual mode information of neighboring CUs. Experimental result shows that the proposed algorithm achieves the average time-saving factor of 44.84% in the random access (RA at Main profile configuration with the HEVC test model (HM 10.0 reference software. Compared to HM 10.0 encoder, a small BD-bitrate loss of 0.17% is also observed without significant loss of image quality.
15. EUROGAM: A high efficiency escape suppressed spectrometer array
Energy Technology Data Exchange (ETDEWEB)
Nolan, P J [Liverpool Univ. (United Kingdom). Oliver Lodge Lab.
1992-08-01
EUROGAM is a UK-France collaboration to develop and build a high efficiency escape suppressed spectrometer array. The project has involved the development of both germanium (Ge) and bismuth germanate (BGO) detectors to produce crystals which are both bigger and have a more complex geometry. As a major investment for the future, the collaboration has developed a new electronics and data acquisition system based on the VXI and VME standards. The array will start its experimental programme in mid 1992 at the Nuclear Structure Facility at Daresbury, U.K. At this stage it will have a total photopeak efficiency (for 1.33 MeV gamma-rays) of {approx} 4.5%. This will give an improvement in sensitivity (relative to presently operating arrays) of a factor of about 10. When EUROGAM moves to France in mid 1993 its photopeak efficiency will have increased to about 8.5% which will result in an increase in sensitivity of a further factor of about 10. In this article I will concentrate on the array which will operate at Daresbury in 1992 and only briefly cover the developments which will take place for the full array before it is used in France in 1993. (author). 13 refs., 2 tabs., 10 figs.
16. High Power High Efficiency Diode Laser Stack for Processing
Science.gov (United States)
Gu, Yuanyuan; Lu, Hui; Fu, Yueming; Cui, Yan
2018-03-01
High-power diode lasers based on GaAs semiconductor bars are well established as reliable and highly efficient laser sources. As diode laser is simple in structure, small size, longer life expectancy with the advantages of low prices, it is widely used in the industry processing, such as heat treating, welding, hardening, cladding and so on. Respectively, diode laser could make it possible to establish the practical application because of rectangular beam patterns which are suitable to make fine bead with less power. At this power level, it can have many important applications, such as surgery, welding of polymers, soldering, coatings and surface treatment of metals. But there are some applications, which require much higher power and brightness, e.g. hardening, key hole welding, cutting and metal welding. In addition, High power diode lasers in the military field also have important applications. So all developed countries have attached great importance to high-power diode laser system and its applications. This is mainly due their low performance. In this paper we will introduce the structure and the principle of the high power diode stack.
17. High-efficiency ballistic electrostatic generator using microdroplets
Science.gov (United States)
Xie, Yanbo; Bos, Diederik; de Vreede, Lennart J.; de Boer, Hans L.; van der Meulen, Mark-Jan; Versluis, Michel; Sprenkels, Ad J.; van den Berg, Albert; Eijkel, Jan C. T.
2014-04-01
The strong demand for renewable energy promotes research on novel methods and technologies for energy conversion. Microfluidic systems for energy conversion by streaming current are less known to the public, and the relatively low efficiencies previously obtained seemed to limit the further applications of such systems. Here we report a microdroplet-based electrostatic generator operating by an acceleration-deceleration cycle (‘ballistic’ conversion), and show that this principle enables both high efficiency and compact simple design. Water is accelerated by pumping it through a micropore to form a microjet breaking up into fast-moving charged droplets. Droplet kinetic energy is converted to electrical energy when the charged droplets decelerate in the electrical field that forms between membrane and target. We demonstrate conversion efficiencies of up to 48%, a power density of 160 kW m-2 and both high- (20 kV) and low- (500 V) voltage operation. Besides offering striking new insights, the device potentially opens up new perspectives for low-cost and robust renewable energy conversion.
18. High Efficiency Hydrodynamic DNA Fragmentation in a Bubbling System.
Science.gov (United States)
Li, Lanhui; Jin, Mingliang; Sun, Chenglong; Wang, Xiaoxue; Xie, Shuting; Zhou, Guofu; van den Berg, Albert; Eijkel, Jan C T; Shui, Lingling
2017-01-18
DNA fragmentation down to a precise fragment size is important for biomedical applications, disease determination, gene therapy and shotgun sequencing. In this work, a cheap, easy to operate and high efficiency DNA fragmentation method is demonstrated based on hydrodynamic shearing in a bubbling system. We expect that hydrodynamic forces generated during the bubbling process shear the DNA molecules, extending and breaking them at the points where shearing forces are larger than the strength of the phosphate backbone. Factors of applied pressure, bubbling time and temperature have been investigated. Genomic DNA could be fragmented down to controllable 1-10 Kbp fragment lengths with a yield of 75.30-91.60%. We demonstrate that the ends of the genomic DNAs generated from hydrodynamic shearing can be ligated by T4 ligase and the fragmented DNAs can be used as templates for polymerase chain reaction. Therefore, in the bubbling system, DNAs could be hydrodynamically sheared to achieve smaller pieces in dsDNAs available for further processes. It could potentially serve as a DNA sample pretreatment technique in the future.
19. Highly Efficient and Reproducible Nonfullerene Solar Cells from Hydrocarbon Solvents
KAUST Repository
2017-06-01
With chlorinated solvents unlikely to be permitted for use in solution-processed organic solar cells in industry, there must be a focus on developing nonchlorinated solvent systems. Here we report high-efficiency devices utilizing a low-bandgap donor polymer (PffBT4T-2DT) and a nonfullerene acceptor (EH-IDTBR) from hydrocarbon solvents and without using additives. When mesitylene was used as the solvent, rather than chlorobenzene, an improved power conversion efficiency (11.1%) was achieved without the need for pre- or post-treatments. Despite altering the processing conditions to environmentally friendly solvents and room-temperature coating, grazing incident X-ray measurements confirmed that active layers processed from hydrocarbon solvents retained the robust nanomorphology obtained with hot-processed chlorinated solvents. The main advantages of hydrocarbon solvent-processed devices, besides the improved efficiencies, were the reproducibility and storage lifetime of devices. Mesitylene devices showed better reproducibility and shelf life up to 4000 h with PCE dropping by only 8% of its initial value.
20. A Novel High Efficiency Fractal Multiview Video Codec
Directory of Open Access Journals (Sweden)
Shiping Zhu
2015-01-01
Full Text Available Multiview video which is one of the main types of three-dimensional (3D video signals, captured by a set of video cameras from various viewpoints, has attracted much interest recently. Data compression for multiview video has become a major issue. In this paper, a novel high efficiency fractal multiview video codec is proposed. Firstly, intraframe algorithm based on the H.264/AVC intraprediction modes and combining fractal and motion compensation (CFMC algorithm in which range blocks are predicted by domain blocks in the previously decoded frame using translational motion with gray value transformation is proposed for compressing the anchor viewpoint video. Then temporal-spatial prediction structure and fast disparity estimation algorithm exploiting parallax distribution constraints are designed to compress the multiview video data. The proposed fractal multiview video codec can exploit temporal and spatial correlations adequately. Experimental results show that it can obtain about 0.36 dB increase in the decoding quality and 36.21% decrease in encoding bitrate compared with JMVC8.5, and the encoding time is saved by 95.71%. The rate-distortion comparisons with other multiview video coding methods also demonstrate the superiority of the proposed scheme.
1. High efficiency video coding (HEVC) algorithms and architectures
CERN Document Server
2014-01-01
This book provides developers, engineers, researchers and students with detailed knowledge about the High Efficiency Video Coding (HEVC) standard. HEVC is the successor to the widely successful H.264/AVC video compression standard, and it provides around twice as much compression as H.264/AVC for the same level of quality. The applications for HEVC will not only cover the space of the well-known current uses and capabilities of digital video – they will also include the deployment of new services and the delivery of enhanced video quality, such as ultra-high-definition television (UHDTV) and video with higher dynamic range, wider range of representable color, and greater representation precision than what is typically found today. HEVC is the next major generation of video coding design – a flexible, reliable and robust solution that will support the next decade of video applications and ease the burden of video on world-wide network traffic. This book provides a detailed explanation of the various parts ...
2. A High Efficiency PSOFC/ATS-Gas Turbine Power System
Energy Technology Data Exchange (ETDEWEB)
W.L. Lundberg; G.A. Israelson; M.D. Moeckel; S.E. Veyo; R.A. Holmes; P.R. Zafred; J.E. King; R.E. Kothmann
2001-02-01
A study is described in which the conceptual design of a hybrid power system integrating a pressurized Siemens Westinghouse solid oxide fuel cell generator and the Mercury{trademark} 50 gas turbine was developed. The Mercury{trademark} 50 was designed by Solar Turbines as part of the US. Department of Energy Advanced Turbine Systems program. The focus of the study was to develop the hybrid power system concept that principally would exhibit an attractively-low cost of electricity (COE). The inherently-high efficiency of the hybrid cycle contributes directly to achieving this objective, and by employing the efficient, power-intensive Mercury{trademark} 50, with its relatively-low installed cost, the higher-cost SOFC generator can be optimally sized such that the minimum-COE objective is achieved. The system cycle is described, major system components are specified, the system installed cost and COE are estimated, and the physical arrangement of the major system components is discussed. Estimates of system power output, efficiency, and emissions at the system design point are also presented. In addition, two bottoming cycle options are described, and estimates of their effects on overall-system performance, cost, and COE are provided.
3. EUROGAM: A high efficiency escape suppressed spectrometer array
International Nuclear Information System (INIS)
Nolan, P.J.
1992-01-01
EUROGAM is a UK-France collaboration to develop and build a high efficiency escape suppressed spectrometer array. The project has involved the development of both germanium (Ge) and bismuth germanate (BGO) detectors to produce crystals which are both bigger and have a more complex geometry. As a major investment for the future, the collaboration has developed a new electronics and data acquisition system based on the VXI and VME standards. The array will start its experimental programme in mid 1992 at the Nuclear Structure Facility at Daresbury, U.K. At this stage it will have a total photopeak efficiency (for 1.33 MeV gamma-rays) of ∼ 4.5%. This will give an improvement in sensitivity (relative to presently operating arrays) of a factor of about 10. When EUROGAM moves to France in mid 1993 its photopeak efficiency will have increased to about 8.5% which will result in an increase in sensitivity of a further factor of about 10. In this article I will concentrate on the array which will operate at Daresbury in 1992 and only briefly cover the developments which will take place for the full array before it is used in France in 1993. (author). 13 refs., 2 tabs., 10 figs
4. Characterization of three high efficiency and blue sensitive silicon photomultipliers
Energy Technology Data Exchange (ETDEWEB)
Otte, Adam Nepomuk, E-mail: otte@gatech.edu; Garcia, Distefano; Nguyen, Thanh; Purushotham, Dhruv
2017-02-21
We report about the optical and electrical characterization of three high efficiency and blue sensitive Silicon photomultipliers from FBK, Hamamatsu, and SensL. Key features of the tested devices when operated at 90% breakdown probability are peak photon detection efficiencies between 40% and 55%, temperature dependencies of gain and PDE that are less than 1%/°C, dark rates of ∼50 kHz/mm{sup 2} at room temperature, afterpulsing of about 2%, and direct optical crosstalk between 6% and 20%. The characteristics of all three devices impressively demonstrate how the Silicon-photomultiplier technology has improved over the past ten years. It is further demonstrated how the voltage and temperature characteristics of a number of quantities can be parameterized on the basis of physical models. The models provide a deeper understanding of the device characteristics over a wide bias and temperature range. They also serve as examples how producers could provide the characteristics of their SiPMs to users. A standardized parameterization of SiPMs would enable users to find the optimal SiPM for their application and the operating point of SiPMs without having to perform measurements thus significantly reducing design and development cycles.
5. Thin Film Packaging Solutions for High Efficiency OLED Lighting Products
Energy Technology Data Exchange (ETDEWEB)
None
2008-06-30
The objective of the 'Thin Film Packaging Solutions for High Efficiency OLED Lighting Products' project is to demonstrate thin film packaging solutions based on SiC hermetic coatings that, when applied to glass and plastic substrates, support OLED lighting devices by providing longer life with greater efficiency at lower cost than is currently available. Phase I Objective: Demonstrate thin film encapsulated working phosphorescent OLED devices on optical glass with lifetime of 1,000 hour life, CRI greater than 75, and 15 lm/W. Phase II Objective: Demonstrate thin film encapsulated working phosphorescent OLED devices on plastic or glass composite with 25 lm/W, 5,000 hours life, and CRI greater than 80. Phase III Objective: Demonstrate 2 x 2 ft{sup 2} thin film encapsulated working phosphorescent OLED with 40 lm/W, 10,000 hour life, and CRI greater than 85. This report details the efforts of Phase III (Budget Period Three), a fourteen month collaborative effort that focused on optimization of high-efficiency phosphorescent OLED devices and thin-film encapsulation of said devices. The report further details the conclusions and recommendations of the project team that have foundation in all three budget periods for the program. During the conduct of the Thin Film Packaging Solutions for High Efficiency OLED Lighting Products program, including budget period three, the project team completed and delivered the following achievements: (1) a three-year marketing effort that characterized the near-term and longer-term OLED market, identified customer and consumer lighting needs, and suggested prototype product concepts and niche OLED applications lighting that will give rise to broader market acceptance as a source for wide area illumination and energy conservation; (2) a thin film encapsulation technology with a lifetime of nearly 15,000 hours, tested by calcium coupons, while stored at 16 C and 40% relative humidity ('RH'). This encapsulation technology
6. Highly Efficient Spectrally Stable Red Perovskite Light-Emitting Diodes.
Science.gov (United States)
Tian, Yu; Zhou, Chenkun; Worku, Michael; Wang, Xi; Ling, Yichuan; Gao, Hanwei; Zhou, Yan; Miao, Yu; Guan, Jingjiao; Ma, Biwu
2018-05-01
Perovskite light-emitting diodes (LEDs) have recently attracted great research interest for their narrow emissions and solution processability. Remarkable progress has been achieved in green perovskite LEDs in recent years, but not blue or red ones. Here, highly efficient and spectrally stable red perovskite LEDs with quasi-2D perovskite/poly(ethylene oxide) (PEO) composite thin films as the light-emitting layer are reported. By controlling the molar ratios of organic salt (benzylammonium iodide) to inorganic salts (cesium iodide and lead iodide), luminescent quasi-2D perovskite thin films are obtained with tunable emission colors from red to deep red. The perovskite/polymer composite approach enables quasi-2D perovskite/PEO composite thin films to possess much higher photoluminescence quantum efficiencies and smoothness than their neat quasi-2D perovskite counterparts. Electrically driven LEDs with emissions peaked at 638, 664, 680, and 690 nm have been fabricated to exhibit high brightness and external quantum efficiencies (EQEs). For instance, the perovskite LED with an emission peaked at 680 nm exhibits a brightness of 1392 cd m -2 and an EQE of 6.23%. Moreover, exceptional electroluminescence spectral stability under continuous device operation has been achieved for these red perovskite LEDs. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
7. Metamaterial Receivers for High Efficiency Concentrated Solar Energy Conversion
Energy Technology Data Exchange (ETDEWEB)
Yellowhair, Julius E. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Concentrating Solar Technologies Dept.; Kwon, Hoyeong [Univ. of Texas, Austin, TX (United States). Dept. of Electrical and Computer Engineering; Alu, Andrea [Univ. of Texas, Austin, TX (United States). Dept. of Electrical and Computer Engineering; Jarecki, Robert L. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Concentrating Solar Technologies Dept.; Shinde, Subhash L. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Concentrating Solar Technologies Dept.
2016-09-01
Operation of concentrated solar power receivers at higher temperatures (>700°C) would enable supercritical carbon dioxide (sCO2) power cycles for improved power cycle efficiencies (>50%) and cost-effective solar thermal power. Unfortunately, radiative losses at higher temperatures in conventional receivers can negatively impact the system efficiency gains. One approach to improve receiver thermal efficiency is to utilize selective coatings that enhance absorption across the visible solar spectrum while minimizing emission in the infrared to reduce radiative losses. Existing coatings, however, tend to degrade rapidly at elevated temperatures. In this report, we report on the initial designs and fabrication of spectrally selective metamaterial-based absorbers for high-temperature, high-thermal flux environments important for solarized sCO2 power cycles. Metamaterials are structured media whose optical properties are determined by sub-wavelength structural features instead of bulk material properties, providing unique solutions by decoupling the optical absorption spectrum from thermal stability requirements. The key enabling innovative concept proposed is the use of structured surfaces with spectral responses that can be tailored to optimize the absorption and retention of solar energy for a given temperature range. In this initial study through the Academic Alliance partnership with University of Texas at Austin, we use Tungsten for its stability in expected harsh environments, compatibility with microfabrication techniques, and required optical performance. Our goal is to tailor the optical properties for high (near unity) absorptivity across the majority of the solar spectrum and over a broad range of incidence angles, and at the same time achieve negligible absorptivity in the near infrared to optimize the energy absorbed and retained. To this goal, we apply the recently developed concept of plasmonic Brewster angle to suitably designed
8. High efficiency semimetal/semiconductor nanocomposite thermoelectric materials
International Nuclear Information System (INIS)
Zide, J. M. O.; Bahk, J.-H.; Zeng, G.; Bowers, J. E.; Singh, R.; Zebarjadi, M.; Bian, Z. X.; Shakouri, A.; Lu, H.; Gossard, A. C.; Feser, J. P.; Xu, D.; Singer, S. L.; Majumdar, A.
2010-01-01
Rare-earth impurities in III-V semiconductors are known to self-assemble into semimetallic nanoparticles which have been shown to reduce lattice thermal conductivity without harming electronic properties. Here, we show that adjusting the band alignment between ErAs and In 0.53 Ga 0.47-X Al X As allows energy-dependent scattering of carriers that can be used to increase thermoelectric power factor. Films of various Al concentrations were grown by molecular beam epitaxy, and thermoelectric properties were characterized. We observe concurrent increases in electrical conductivity and Seebeck coefficient with increasing temperatures, demonstrating energy-dependent scattering. We report the first simultaneous power factor enhancement and thermal conductivity reduction in a nanoparticle-based system, resulting in a high figure of merit, ZT=1.33 at 800 K.
9. High efficiency power production from biomass and waste
Energy Technology Data Exchange (ETDEWEB)
Rabou, L.P.L.M.; Van Leijenhorst, R.J.C.; Hazewinkel, J.H.O. [ECN Biomass, Coal and Environment, Petten (Netherlands)
2008-11-15
Two-stage gasification allows power production from biomass and waste with high efficiency. The process involves pyrolysis at about 550C followed by heating of the pyrolysis gas to about 1300C in order to crack hydrocarbons and obtain syngas, a mixture of H2, CO, H2O and CO2. The second stage produces soot as unwanted by-product. Experimental results are reported on the suppression of soot formation in the second stage for two different fuels: beech wood pellets and Rofire pellets, made from rejects of paper recycling. Syngas obtained from these two fuels and from an industrial waste fuel has been cleaned and fed to a commercial SOFC stack for 250 hours in total. The SOFC stack showed comparable performance on real and synthetic syngas and no signs of accelerated degradation in performance over these tests. The experimental results have been used for the design and analysis of a future 25 MWth demonstration plant. As an alternative, a 2.6 MWth system was considered which uses the Green MoDem approach to convert waste fuel into bio-oil and syngas. The 25 MWth system can reach high efficiency only if char produced in the pyrolysis step is converted into additional syngas by steam gasification, and if SOFC off-gas and system waste heat are used in a steam bottoming cycle for additional power production. A net electrical efficiency of 38% is predicted. In addition, heat can be delivered with 37% efficiency. The 2.6 MWth system with only a dual fuel engine to burn bio-oil and syngas promises nearly 40% electrical efficiency plus 41% efficiency for heat production. If syngas is fed to an SOFC system and off-gas and bio-oil to a dual fuel engine, the electrical efficiency can rise to 45%. However, the efficiency for heat production drops to 15%, as waste heat from the SOFC system cannot be used effectively. The economic analysis makes clear that at -20 euro/tonne fuel, 70 euro/MWh for electricity and 7 euro/GJ for heat the 25 MWth system is not economically viable at the
10. [Tobacco--a highly efficient producer of vaccines].
Science.gov (United States)
Budzianowski, Jaromir
2010-01-01
Along with the depreciation of tobacco as a source of nicotine-containing commercial products, the increase of its appreciation as a potential producer of recombinant therapeutical proteins can be observed. Two species of tobacco--Nicotiana tabacum L. and N. benthamiana are easily grown by well established methods of field or green-house cultivation or cell culture, yield high biomass and soluble protein content, can be easily transformed by several methods and are not food for humans or feed for animals. Expression of foreign proteins, including vaccines, can be achieved in those plants either through stable transformation of nuclear or plastid (chloroplast) genomes or by transient transformation using infection with plant virus or bacteria--Agrobacterium tumefaciens (agroinfiltration). The most advanced mode of agrofiltration termed magnifection, which combines benefits of virus and Agrobacterium and depends on using Agrobacterium with viral pro-vectors, enables high-yield and rapid expression of therapeutical proteins, even in a few days, and can be employed on an industrial scale. Expression of many antigenic proteins, which may serve as antiviral, antibacterial, antiprotozoan and anticancer vaccines, and additionally a few autoantigens designed for the treatment of autoimunogenic diseases, like diabetes, have been achieved in tobacco. To date, a vaccine against Newcastle virus disease in poultry produced by tobacco cell culture has been approved for commercial application and several other vaccines are in advanced stage of development. The possibility of a high-level production of vaccines in tobacco against pandemic influenza or anthrax and plague due to a bioterroristic attack, as well as of individualised anticancer vaccines against non-Hodgkin's lymphoma (NHL) in a much shorter period of time than by traditional methods became realistic and hence caused increased interest in tobacco as a high-efficient producer of vaccines not only of specialistic
11. High efficiency, multiterawatt x-ray free electron lasers
Directory of Open Access Journals (Sweden)
C. Emma
2016-02-01
Full Text Available In this paper we present undulator magnet tapering methods for obtaining high efficiency and multiterawatt peak powers in x-ray free electron lasers (XFELs, a key requirement for enabling 3D atomic resolution single molecule imaging and nonlinear x-ray science. The peak power and efficiency of tapered XFELs is sensitive to time dependent effects, like synchrotron sideband growth. To analyze this dependence in detail we perform a comparative numerical optimization for the undulator magnetic field tapering profile including and intentionally disabling these effects. We show that the solution for the magnetic field taper profile obtained from time independent optimization does not yield the highest extraction efficiency when time dependent effects are included. Our comparative optimization is performed for a novel undulator designed specifically to obtain TW power x-ray pulses in the shortest distance: superconducting, helical, with short period and built-in strong focusing. This design reduces the length of the breaks between modules, decreasing diffraction effects, and allows using a stronger transverse electron focusing. Both effects reduce the gain length and the overall undulator length. We determine that after a fully time dependent optimization of a 100 m long Linac coherent light source-like XFEL we can obtain a maximum efficiency of 7%, corresponding to 3.7 TW peak radiation power. Possible methods to suppress the synchrotron sidebands, and further enhance the FEL peak power, up to about 6 TW by increasing the seed power and reducing the electron beam energy spread, are also discussed.
12. Progress of High Efficiency Centrifugal Compressor Simulations Using TURBO
Science.gov (United States)
Kulkarni, Sameer; Beach, Timothy A.
2017-01-01
Three-dimensional, time-accurate, and phase-lagged computational fluid dynamics (CFD) simulations of the High Efficiency Centrifugal Compressor (HECC) stage were generated using the TURBO solver. Changes to the TURBO Parallel Version 4 source code were made in order to properly model the no-slip boundary condition along the spinning hub region for centrifugal impellers. A startup procedure was developed to generate a converged flow field in TURBO. This procedure initialized computations on a coarsened mesh generated by the Turbomachinery Gridding System (TGS) and relied on a method of systematically increasing wheel speed and backpressure. Baseline design-speed TURBO results generally overpredicted total pressure ratio, adiabatic efficiency, and the choking flow rate of the HECC stage as compared with the design-intent CFD results of Code Leo. Including diffuser fillet geometry in the TURBO computation resulted in a 0.6 percent reduction in the choking flow rate and led to a better match with design-intent CFD. Diffuser fillets reduced annulus cross-sectional area but also reduced corner separation, and thus blockage, in the diffuser passage. It was found that the TURBO computations are somewhat insensitive to inlet total pressure changing from the TURBO default inlet pressure of 14.7 pounds per square inch (101.35 kilopascals) down to 11.0 pounds per square inch (75.83 kilopascals), the inlet pressure of the component test. Off-design tip clearance was modeled in TURBO in two computations: one in which the blade tip geometry was trimmed by 12 mils (0.3048 millimeters), and another in which the hub flow path was moved to reflect a 12-mil axial shift in the impeller hub, creating a step at the hub. The one-dimensional results of these two computations indicate non-negligible differences between the two modeling approaches.
13. Thermal Catalytic Syngas Cleanup for High-Efficiency Waste-to-Energy Converters
Science.gov (United States)
2015-12-01
recuperator used was an off-the-shelf item that is used for high-temperature (1150°C) heat recovery in industrial furnaces. It was a shell -and-tube...design and was installed such that the raw syngas passed within the tubes and the reformed gas passed through the shell side. Figure 11...R.Q.; Monfort, S.M.; Arkenberg, G.B.; Matter, P.H.; Swartz, S.L. Sulfur Tolerant Magnesium Nickel Silicate Catalyst for Reforming of Biomass
14. Large-Scale Nanophotonic Solar Selective Absorbers for High-Efficiency Solar Thermal Energy Conversion.
Science.gov (United States)
Li, Pengfei; Liu, Baoan; Ni, Yizhou; Liew, Kaiyang Kevin; Sze, Jeff; Chen, Shuo; Shen, Sheng
2015-08-19
An omnidirectional nanophotonic solar selective absorber is fabricated on a large scale using a template-stripping method. The nanopyramid nickel structure achieves an average absorptance of 95% at a wavelength range below 1.3 μm and a low emittance less than 10% at wavelength >2.5 μm. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
15. Graphene-based vdW heterostructure Induced High-efficiency Thermoelectric Devices
Science.gov (United States)
Liang, Shijun; Ang, Lay Kee
Thermoelectric material (TE) can convert the heat into electricity to provide green energy source and its performance is characterized by a figure of merit (ZT) parameter. Traditional TE materials only give ZT equal to around 1 at room temperature. But, it is believed that materials with ZT >3 will find wide applications at this low temperature range. Prior studies have implied that the interrelation between electric conductivity and lattice thermal conductivity renders the goal of engineering ZT of bulk materials to reach ZT >3. In this work, we propose a high-efficiency van del Waals (vdW) heterostructure-based thermionic device with graphene electrodes, which is able to harvest wasted heat (around 400K) based on the newly established thermionic emission law of graphene electrodes instead of Seebeck effect, to boost the efficiency of power generation over 10% around room temperature. The efficiency can be above 20% if the Schottky barrier height and cross-plane lattice thermal conductivity of transition metal dichacogenides (TMD) materials can be fine-engineered. As a refrigerator at 260 K, the efficiency is 50% to 80% of Carnot efficiency. Finally, we identify two TMD materials as the ideal candidates of graphene/TMD/graphene devices based on the state-of-art technology.
16. Investigation on the Potential of High Efficiency for Internal Combustion Engines
Directory of Open Access Journals (Sweden)
Haifeng Liu
2018-02-01
Full Text Available The current brake thermal efficiency of advanced internal combustion engines is limited to 50%, and how to further improve the efficiency is a challenge. In this study, a theoretical investigation on engine thermal efficiency was carried out using one-dimension simulations based on the first law of thermodynamics. The energy balance was evaluated by varying parameters such as compression ratio (CR; heat transfer coefficient; intake charge properties; and combustion phasing etc.—their influences on the efficiency limits were demonstrated. Results show that for a given heat transfer coefficient, an optimal CR exists to obtain the peak efficiency. The optimal CR decreases with the increase of heat transfer coefficient, and high CR with a low heat-transfer coefficient can achieve a significantly high efficiency. A higher density and specific heat ratio of intake charge, as well as a shorter combustion duration with a proper CA50 (crank angle at 50% of total heat release, can increase efficiency significantly. Methanol shows an excellent ability in decreasing the peak in-cylinder temperature; and the peak indicated efficiency is relatively higher than other tested fuels. The displacement has few effects on the indicated efficiency, while it shows a strong effect on the energy distribution between heat transfer and exhaust energy. All these strategies with high CR result in high in-cylinder pressure and temperature; which means a breakthrough of material is needed in the future.
17. Highly efficient DNA extraction method from skeletal remains
Directory of Open Access Journals (Sweden)
Irena Zupanič Pajnič
2011-03-01
Full Text Available Background: This paper precisely describes the method of DNA extraction developed to acquire high quality DNA from the Second World War skeletal remains. The same method is also used for molecular genetic identification of unknown decomposed bodies in routine forensic casework where only bones and teeth are suitable for DNA typing. We analysed 109 bones and two teeth from WWII mass graves in Slovenia. Methods: We cleaned the bones and teeth, removed surface contaminants and ground the bones into powder, using liquid nitrogen . Prior to isolating the DNA in parallel using the BioRobot EZ1 (Qiagen, the powder was decalcified for three days. The nuclear DNA of the samples were quantified by real-time PCR method. We acquired autosomal genetic profiles and Y-chromosome haplotypes of the bones and teeth with PCR amplification of microsatellites, and mtDNA haplotypes 99. For the purpose of traceability in the event of contamination, we prepared elimination data bases including genetic profiles of the nuclear and mtDNA of all persons who have been in touch with the skeletal remains in any way. Results: We extracted up to 55 ng DNA/g of the teeth, up to 100 ng DNA/g of the femurs, up to 30 ng DNA/g of the tibias and up to 0.5 ng DNA/g of the humerus. The typing of autosomal and YSTR loci was successful in all of the teeth, in 98 % dekalof the femurs, and in 75 % to 81 % of the tibias and humerus. The typing of mtDNA was successful in all of the teeth, and in 96 % to 98 % of the bones. Conclusions: We managed to obtain nuclear DNA for successful STR typing from skeletal remains that were over 60 years old . The method of DNA extraction described here has proved to be highly efficient. We obtained 0.8 to 100 ng DNA/g of teeth or bones and complete genetic profiles of autosomal DNA, Y-STR haplotypes, and mtDNA haplotypes from only 0.5g bone and teeth samples.
18. High efficiency combined heat and power facilities - benefits and barriers
International Nuclear Information System (INIS)
Klein, M.
2001-01-01
There are important linkages between the economy, energy production, the environment and our health. Where thermal energy is needed, distributed Combined Heat and Power facilities, using gas turbines, reciprocating engines and future fuel cells can provide significant improvements to our long term mix of energy production. Local generation can also have benefits in security of energy supply and economic savings. This paper is intended to discuss the relevant air pollution and greenhouse gas emissions from modem CHP plants, the emission prevention and reduction methods available, and their operating experience and cost-effectiveness. Mention is made of recently constructed industrial and commercial plants, and institutional barriers to further development. Solutions described for these barriers include the need for more awareness of opportunities, improved access to the electricity grid, the proper design balance between thermal and electric for CHP systems rather than large combined cycles, improved corporate taxation incentives, and the assessment of all environmental and economic benefits when considering such cleaner sources in a restructured energy market. (author)
19. Simulation of a high efficiency multi-bed adsorption heat pump
International Nuclear Information System (INIS)
TeGrotenhuis, W.E.; Humble, P.H.; Sweeney, J.B.
2012-01-01
Attaining high energy efficiency with adsorption heat pumps is challenging due to thermodynamic losses that occur when the sorbent beds are thermally cycled without effective heat recuperation. The multi-bed concept described here enables high efficiency by effectively transferring heat from beds being cooled to beds being heated. A simplified lumped-parameter model and detailed finite element analysis are used to simulate a sorption compressor, which is used to project the overall heat pump coefficient of performance. Results are presented for ammonia refrigerant and a nano-structured monolithic carbon sorbent specifically modified for the application. The effects of bed geometry and number of beds on system performance are explored, and the majority of the performance benefit is obtained with four beds. Results indicate that a COP of 1.24 based on heat input is feasible at AHRI standard test conditions for residential HVAC equipment. When compared on a basis of primary energy input, performance equivalent to SEER 13 or 14 are theoretically attainable with this system. - Highlights: ► A multi-bed concept for adsorption heat pumps is capable of high efficiency. ► Modeling is used to simulate sorption compressor and overall heat pump performance. ► Results are presented for ammonia refrigerant and a nano-structured monolithic carbon sorbent. ► The majority of the efficiency benefit is obtained with four beds. ► Predicted COP as high as 1.24 for cooling is comparable to SEER 13 or 14 for electric heat pumps.
20. Technology Roadmap: High-Efficiency, Low-Emissions Coal-Fired Power Generation
Energy Technology Data Exchange (ETDEWEB)
NONE
2012-07-01
Coal is the largest source of power globally and, given its wide availability and relatively low cost, it is likely to remain so for the foreseeable future. The High-Efficiency, Low-Emissions Coal-Fired Power Generation Roadmap describes the steps necessary to adopt and further develop technologies to improve the efficiency of the global fleet of coal. To generate the same amount of electricity, a more efficient coal-fired unit will burn less fuel, emit less carbon, release less local air pollutants, consume less water and have a smaller footprint. High-efficiency, low emissions (HELE) technologies in operation already reach a thermal efficiency of 45%, and technologies in development promise even higher values. This compares with a global average efficiency for today’s fleet of coal-fired plants of 33%, where three-quarters of operating units use less efficient technologies and more than half is over 25 years old. A successful outcome to ongoing RD&D could see units with efficiencies approaching 50% or even higher demonstrated within the next decade. Generation from older, less efficient technology must gradually be phased out. Technologies exist to make coal-fired power generation much more effective and cleaner burning. Of course, while increased efficiency has a major role to play in reducing emissions, particularly over the next 10 years, carbon capture and storage (CCS) will be essential in the longer term to make the deep cuts in carbon emissions required for a low-carbon future. Combined with CCS, HELE technologies can cut CO2 emissions from coal-fired power generation plants by as much as 90%, to less than 100 grams per kilowatt-hour. HELE technologies will be an influential factor in the deployment of CCS. For the same power output, a higher efficiency coal plant will require less CO2 to be captured; this means a smaller, less costly capture plant; lower operating costs; and less CO2 to be transported and stored.
1. Combustion phasing for maximum efficiency for conventional and high efficiency engines
International Nuclear Information System (INIS)
Caton, Jerald A.
2014-01-01
Highlights: • Combustion phasing for max efficiency is a function of engine parameters. • Combustion phasing is most affected by heat transfer, compression ratio, burn duration. • Combustion phasing is less affected by speed, load, equivalence ratio and EGR. • Combustion phasing for a high efficiency engine was more advanced. • Exergy destruction during combustion as functions of combustion phasing is reported. - Abstract: The importance of the phasing of the combustion event for internal-combustion engines is well appreciated, but quantitative details are sparse. The objective of the current work was to examine the optimum combustion phasing (based on maximum bmep) as functions of engine design and operating variables. A thermodynamic, engine cycle simulation was used to complete this assessment. As metrics for the combustion phasing, both the crank angle for 50% fuel mass burned (CA 50 ) and the crank angle for peak pressure (CA pp ) are reported as functions of the engine variables. In contrast to common statements in the literature, the optimum CA 50 and CA pp vary depending on the design and operating variables. Optimum, as used in this paper, refers to the combustion timing that provides the maximum bmep and brake thermal efficiency (MBT timing). For this work, the variables with the greatest influence on the optimum CA 50 and CA pp were the heat transfer level, the burn duration and the compression ratio. Other variables such as equivalence ratio, EGR level, engine speed and engine load had a much smaller impact on the optimum CA 50 and CA pp . For the conventional engine, for the conditions examined, the optimum CA 50 varied between about 5 and 11°aTDC, and the optimum CA pp varied between about 9 and 16°aTDC. For a high efficiency engine (high dilution, high compression ratio), the optimum CA 50 was 2.5°aTDC, and the optimum CA pp was 7.8°aTDC. These more advanced values for the optimum CA 50 and CA pp for the high efficiency engine were
2. High efficiency targets for high gain inertial confinement fusion
International Nuclear Information System (INIS)
Gardner, J.H.; Bodner, S.E.
1986-01-01
Rocket efficiencies as high as 15% are possible using short wavelength lasers and moderately high aspect ratio pellet designs. These designs are made possible by two recent breakthroughs in physics constraints. First is the development of the Induced Spatial Incoherence (ISI) technique which allows uniform illumination of the pellet and relaxes the constraint of thermal smoothing, permitting the use of short wavelength laser light. Second is the discovery that the Rayleigh-Taylor growth rate is considerably reduced at the short laser wavelengths. By taking advantage of the reduced constraints imposed by nonuniform laser illumination and Rayleigh-Taylor instability, pellets using 1/4 micron laser light and initial aspect ratios of about 10 (with in flight aspect ratios of about 150 to 200) may produce energy gains as high as 200 to 250
3. Blanket options for high-efficiency fusion power
International Nuclear Information System (INIS)
Usher, J.L.; Lazareth, O.W.; Fillo, J.A.; Horn, F.L.; Powell, J.R.
1980-01-01
The efficiencies of blankets for fusion reactors are usually in the range of 30 to 40%, limited by the operating temperatures (500 0 C) of conventional structural materials such as stainless steels. In this project two-zone blankets are proposed; these blankets consist of a low-temperature shell surrounding a high-temperature interior zone. A survey of nucleonics and thermal hydraulic parameters has led to a reference blanket design consisting of a water-cooled stainless steel shell around a BeO, ZrO 2 interior (cooled by argon) utilizing Li 2 O for tritium breeding. In this design, approximately 60% of the fusion energy is deposited in the high-temperature interior. The maximum argon temperature is 2230 0 C leading to an overall efficiency estimate of 55 to 60% for this reference case
4. Fusion blankets for high-efficiency power cycles
International Nuclear Information System (INIS)
Usher, J.L.; Lazareth, O.W.; Fillo, J.A.; Horn, F.L.; Powell, J.R.
1980-01-01
The efficiencies of blankets for fusion reactors are usually in the range of 30 to 40%, limited by the operating temperatures (500 0 C) of conventional structural materials such as stainless steels. In this project two-zone blankets are proposed; these blankets consist of a low-temperature shell surrounding a high-temperature interior zone. A survey of nucleonics and thermal hydraulic parameters has led to a reference blanket design consisting of a water-cooled stainless steel shell around a BeO, ZrO 2 interior (cooled by argon) utilizing Li 2 O for tritium breeding. In this design, approximately 60% of the fusion energy is deposited in the high-temperature interior. The maximum argon temperature is 2230 0 C leading to an overall efficiency estimate of 55 to 60% for this reference case
5. Fusion blanket for high-efficiency power cycles
International Nuclear Information System (INIS)
Usher, J.L.; Powell, J.R.; Fillo, J.A.; Horn, F.L.; Lazareth, O.W.; Taussig, R.
1980-01-01
The efficiencies of blankets for fusion reactors are usually in the range of 30 to 40%, limited by the operating temperature (500 0 C) of conventional structural materials such as stainless steels. In this project two-zone blankets are proposed; these blankets consist of a low-temperature shell surrounding a high-temperature interior zone. A survey of nucleonics and thermal hydraulic parameters has led to a reference blanket design consisting of a water-cooled stainless steel shell around a BeO, ZrO 2 interior (cooled by Ar) utilizing Li 2 O for tritium breeding. In this design, approx. 60% of the fusion energy is deposited in the high-temperature interior. The maximum Ar temperature is 2230 0 C leading to an overall efficiency estimate of 55 to 60% for this reference case
6. Fusion blankets for high-efficiency power cycles
International Nuclear Information System (INIS)
Usher, J.L.; Lazareth, O.W.; Fillo, J.A.; Horn, F.L.; Powell, J.R.
1981-01-01
The efficiencies of blankets for fusion reactors are usually in the range of 30 to 40%, limited by the operating temperatures (500 deg C) of conventional structural materials such as stainless steels. In this project 'two-zone' blankets are proposed; these blankets consist of a low-temperature shell surrounding a high-temperature interior zone. A survey of nucleonics and thermal hydraulic parameters has led to a reference blanket design consisting of a water-cooled stainless steel shell around a BeO, ZrO 2 interior (cooled by argon) utilizing Li 2 O for tritium breeding. In this design, approximately 60% of the fusion energy is deposited in the high-temperature interior. The maximum argon temperature is 2230 deg C leading to an overall efficiency estimate of 55 to 60% for this reference case. (author)
7. High efficiency polymer solar cells with vertically modulated nanoscale morphology
International Nuclear Information System (INIS)
Kumar, Ankit; Hong Ziruo; Yang Yang; Li Gang
2009-01-01
Nanoscale morphology has been shown to be a critical parameter governing charge transport properties of polymer bulk heterojunction (BHJ) solar cells. Recent results on vertical phase separation have intensified the research on 3D morphology control. In this paper, we intend to modify the distribution of donors and acceptors in a classical BHJ polymer solar cell by making the active layer richer in donors and acceptors near the anode and cathode respectively. Here, we chose [6,6]-phenyl- C 61 -butyric acid methyl ester (PCBM) to be the acceptor material to be thermally deposited on top of [poly(3-hexylthiophene)] P3HT: the PCBM active layer to achieve a vertical composition gradient in the BHJ structure. Here we report on a solar cell with enhanced power conversion efficiency of 4.5% which can be directly correlated with the decrease in series resistance of the device.
8. Highly efficient capture of iodine by Cu/MIL-101
Science.gov (United States)
Qi, Bingbing; Liu, Ying; Zheng, Tao; Gao, Qianhong; Yan, Xuewu; Jiao, Yan; Yang, Yi
2018-02-01
In order to improve the uptake capacity of MIL-101 for iodine, Cu nanoparticles doped MIL-101 were successfully synthesized through a facile method. The obtained Cu/MIL-101 was characterized by SEM, XRD, EDS, TEM, IR, TGA and BET to examine the chemical and thermal stabilities. The capture experiments for the adsorbents showed that the capture capacity of Cu/MIL-101 for volatile iodine is 342 wt%, which is higher than that of pure MIL-101. An I2 uptake of 342 wt% is the highest value reported among metal-organic frameworks. Furthermore, Cu/MIL-101 has a cycle ratio of 95% after three cycles and exhibits a better cyclicity than pure MIL-101. Meanwhile, Cu/MIL-101 shows an excellent reversible adsorption of iodine in solution.
9. High-Efficiency Nitride-Based Solid-State Lighting
Energy Technology Data Exchange (ETDEWEB)
Paul T. Fini; Shuji Nakamura
2005-07-30
In this final technical progress report we summarize research accomplished during Department of Energy contract DE-FC26-01NT41203, entitled ''High-Efficiency Nitride-Based Solid-State Lighting''. Two teams, from the University of California at Santa Barbara (Principle Investigator: Dr. Shuji Nakamura) and the Lighting Research Center at Rensselaer Polytechnic Institute (led by Dr. N. Narendran), pursued the goals of this contract from thin film growth, characterization, and packaging/luminaire design standpoints. The UCSB team initially pursued the development of blue gallium nitride (GaN)-based vertical-cavity surface-emitting lasers, as well as ultraviolet GaN-based light emitting diodes (LEDs). In Year 2, the emphasis shifted to resonant-cavity light emitting diodes, also known as micro-cavity LEDs when extremely thin device cavities are fabricated. These devices have very directional emission and higher light extraction efficiency than conventional LEDs. Via the optimization of thin-film growth and refinement of device processing, we decreased the total cavity thickness to less than 1 {micro}m, such that micro-cavity effects were clearly observed and a light extraction efficiency of over 10% was reached. We also began the development of photonic crystals for increased light extraction, in particular for so-called ''guided modes'' which would otherwise propagate laterally in the device and be re-absorbed. Finally, we pursued the growth of smooth, high-quality nonpolar a-plane and m-plane GaN films, as well as blue light emitting diodes on these novel films. Initial nonpolar LEDs showed the expected behavior of negligible peak wavelength shift with increasing drive current. M-plane LEDs in particular show promise, as unpackaged devices had unsaturated optical output power of {approx} 3 mW at 200 mA drive current. The LRC's tasks were aimed at developing the subcomponents necessary for packaging UCSB's light
10. EVALUATION OF A LOW FRICTION - HIGH EFFICIENCY ROLLER BEARING ENGINE
Energy Technology Data Exchange (ETDEWEB)
Kolarik, Robert V. II; Shattuck, Charles W.; Copper, Anthony P.
2009-06-30
This Low Friction (High Efficiency Roller Bearing) Engine (LFE) report presents the work done by The Timken Company to conduct a technology demonstration of the benefits of replacing hydrodynamic bearings with roller bearings in the crankshaft and camshaft assemblies of an internal combustion engine for the purpose of collecting data sufficient to prove merit. The engines in the present study have been more extensively converted to roller bearings than any previous studies (40 needle roller bearings per engine) to gain understanding of the full potential of application of bearing technology. The project plan called for comparative testing of a production vehicle which was already respected for having demonstrated low engine friction levels with a rollerized version of that engine. Testing was to include industry standard tests for friction, emissions and fuel efficiency conducted on instrumented dynamometers. Additional tests for fuel efficiency, cold start resistance and other measures of performance were to be made in the actual vehicle. Comparative measurements of noise, vibration and harshness (NVH), were planned, although any work to mitigate the suspected higher NVH level in the rollerized engine was beyond the scope of this project. Timken selected the Toyota Avalon with a 3.5L V-6 engine as the test vehicle. In an attempt to minimize cost and fabrication time, a ‘made-from’ approach was proposed in which as many parts as possible would be used or modified from production parts to create the rollerized engine. Timken commissioned its test partner, FEV Engine Technology, to do a feasibility study in which they confirmed that using such an approach was possible to meet the required dimensional restrictions and tolerances. In designing the roller bearing systems for the crank and cam trains, Timken utilized as many production engine parts as possible. The crankshafts were produced from production line forgings, which use Timken steel, modified with special
11. Design Strategies for Ultra-high Efficiency Photovoltaics
Science.gov (United States)
Warmann, Emily Cathryn
While concentrator photovoltaic cells have shown significant improvements in efficiency in the past ten years, once these cells are integrated into concentrating optics, connected to a power conditioning system and deployed in the field, the overall module efficiency drops to only 34 to 36%. This efficiency is impressive compared to conventional flat plate modules, but it is far short of the theoretical limits for solar energy conversion. Designing a system capable of achieving ultra high efficiency of 50% or greater cannot be achieved by refinement and iteration of current design approaches. This thesis takes a systems approach to designing a photovoltaic system capable of 50% efficient performance using conventional diode-based solar cells. The effort began with an exploration of the limiting efficiency of spectrum splitting ensembles with 2 to 20 sub cells in different electrical configurations. Incorporating realistic non-ideal performance with the computationally simple detailed balance approach resulted in practical limits that are useful to identify specific cell performance requirements. This effort quantified the relative benefit of additional cells and concentration for system efficiency, which will help in designing practical optical systems. Efforts to improve the quality of the solar cells themselves focused on the development of tunable lattice constant epitaxial templates. Initially intended to enable lattice matched multijunction solar cells, these templates would enable increased flexibility in band gap selection for spectrum splitting ensembles and enhanced radiative quality relative to metamorphic growth. The III-V material family is commonly used for multijunction solar cells both for its high radiative quality and for the ease of integrating multiple band gaps into one monolithic growth. The band gap flexibility is limited by the lattice constant of available growth templates. The virtual substrate consists of a thin III-V film with the desired
12. Heat: A Highly Efficient Skin Enhancer for Transdermal Drug Delivery
Directory of Open Access Journals (Sweden)
Sabine Szunerits
2018-02-01
Full Text Available Advances in materials science and bionanotechnology have allowed the refinements of current drug delivery systems, expected to facilitate the development of personalized medicine. While dermatological topical pharmaceutical formulations such as foams, creams, lotions, gels, etc., have been proposed for decades, these systems target mainly skin-based diseases. To treat systemic medical conditions as well as localized problems such as joint or muscle concerns, transdermal delivery systems (TDDSs, which use the skin as the main route of drug delivery, are very appealing. Over the years, these systems have shown to offer important advantages over oral as well as intravenous drug delivery routes. Besides being non-invasive and painless, TDDSs are able to deliver drugs with a short-half-life time more easily and are well adapted to eliminate frequent administrations to maintain constant drug delivery. The possibility of self-administration of a predetermined drug dose at defined time intervals makes it also the most convenient personalized point-of-care approach. The transdermal market still remains limited to a narrow range of drugs. While small and lipophilic drugs have been successfully delivered using TDDSs, this approach fails to deliver therapeutic macromolecules due to size-limited transport across the stratum corneum, the outermost layer of the epidermis. The low permeability of the stratum corneum to water-soluble drugs as well as macromolecules poses important challenges to transdermal administration. To widen the scope of drugs for transdermal delivery, new procedures to enhance skin permeation to hydrophilic drugs and macromolecules are under development. Next to iontophoresis and microneedle-based concepts, thermal-based approaches have shown great promise to enhance transdermal drug delivery of different therapeutics. In this inaugural article for the section “Frontiers in Bioengineering and Biotechnology,” the advances in this field
13. Heat: A Highly Efficient Skin Enhancer for Transdermal Drug Delivery.
Science.gov (United States)
Szunerits, Sabine; Boukherroub, Rabah
2018-01-01
Advances in materials science and bionanotechnology have allowed the refinements of current drug delivery systems, expected to facilitate the development of personalized medicine. While dermatological topical pharmaceutical formulations such as foams, creams, lotions, gels, etc., have been proposed for decades, these systems target mainly skin-based diseases. To treat systemic medical conditions as well as localized problems such as joint or muscle concerns, transdermal delivery systems (TDDSs), which use the skin as the main route of drug delivery, are very appealing. Over the years, these systems have shown to offer important advantages over oral as well as intravenous drug delivery routes. Besides being non-invasive and painless, TDDSs are able to deliver drugs with a short-half-life time more easily and are well adapted to eliminate frequent administrations to maintain constant drug delivery. The possibility of self-administration of a predetermined drug dose at defined time intervals makes it also the most convenient personalized point-of-care approach. The transdermal market still remains limited to a narrow range of drugs. While small and lipophilic drugs have been successfully delivered using TDDSs, this approach fails to deliver therapeutic macromolecules due to size-limited transport across the stratum corneum , the outermost layer of the epidermis. The low permeability of the stratum corneum to water-soluble drugs as well as macromolecules poses important challenges to transdermal administration. To widen the scope of drugs for transdermal delivery, new procedures to enhance skin permeation to hydrophilic drugs and macromolecules are under development. Next to iontophoresis and microneedle-based concepts, thermal-based approaches have shown great promise to enhance transdermal drug delivery of different therapeutics. In this inaugural article for the section "Frontiers in Bioengineering and Biotechnology," the advances in this field and the handful of
14. Heat: A Highly Efficient Skin Enhancer for Transdermal Drug Delivery
Science.gov (United States)
Szunerits, Sabine; Boukherroub, Rabah
2018-01-01
Advances in materials science and bionanotechnology have allowed the refinements of current drug delivery systems, expected to facilitate the development of personalized medicine. While dermatological topical pharmaceutical formulations such as foams, creams, lotions, gels, etc., have been proposed for decades, these systems target mainly skin-based diseases. To treat systemic medical conditions as well as localized problems such as joint or muscle concerns, transdermal delivery systems (TDDSs), which use the skin as the main route of drug delivery, are very appealing. Over the years, these systems have shown to offer important advantages over oral as well as intravenous drug delivery routes. Besides being non-invasive and painless, TDDSs are able to deliver drugs with a short-half-life time more easily and are well adapted to eliminate frequent administrations to maintain constant drug delivery. The possibility of self-administration of a predetermined drug dose at defined time intervals makes it also the most convenient personalized point-of-care approach. The transdermal market still remains limited to a narrow range of drugs. While small and lipophilic drugs have been successfully delivered using TDDSs, this approach fails to deliver therapeutic macromolecules due to size-limited transport across the stratum corneum, the outermost layer of the epidermis. The low permeability of the stratum corneum to water-soluble drugs as well as macromolecules poses important challenges to transdermal administration. To widen the scope of drugs for transdermal delivery, new procedures to enhance skin permeation to hydrophilic drugs and macromolecules are under development. Next to iontophoresis and microneedle-based concepts, thermal-based approaches have shown great promise to enhance transdermal drug delivery of different therapeutics. In this inaugural article for the section “Frontiers in Bioengineering and Biotechnology,” the advances in this field and the handful of
15. Highly efficient and durable TiN nanofiber electrocatalyst supports.
Science.gov (United States)
Kim, Hyun; Cho, Min Kyung; Kwon, Jeong An; Jeong, Yeon Hun; Lee, Kyung Jin; Kim, Na Young; Kim, Min Jung; Yoo, Sung Jong; Jang, Jong Hyun; Kim, Hyoung-Juhn; Nam, Suk Woo; Lim, Dong-Hee; Cho, EunAe; Lee, Kwan-Young; Kim, Jin Young
2015-11-28
To date, carbon-based materials including various carbon nanostructured materials have been extensively used as an electrocatalyst support for proton exchange membrane fuel cell (PEMFC) applications due to their practical nature. However, carbon dissolution or corrosion caused by high electrode potential in the presence of O2 and/or water has been identified as one of the main failure modes for the device operation. Here, we report the first TiN nanofiber (TNF)-based nonwoven structured materials to be constructed via electrospinning and subsequent two-step thermal treatment processes as a support for the PEMFC catalyst. Pt catalyst nanoparticles (NPs) deposited on the TNFs (Pt/TNFs) were electrochemically characterized with respect to oxygen reduction reaction (ORR) activity and durability in an acidic medium. From the electrochemical tests, the TNF-supported Pt catalyst was better and more stable in terms of its catalytic performance compared to a commercially available carbon-supported Pt catalyst. For example, the initial oxygen reduction performance was comparable for both cases, while the Pt/TNF showed much higher durability from an accelerated degradation test (ADT) configuration. It is understood that the improved catalytic roles of TNFs on the supported Pt NPs for ORR are due to the high electrical conductivity arising from the extended connectivity, high inertness to the electrochemical environment and strong catalyst-support interactions.
16. High efficiency fluorescent white OLEDs based on DOPPP
Science.gov (United States)
Zhang, Gang; Chen, Chen; Lang, Jihui; Zhao, Lina; Jiang, Wenlong
2017-08-01
The white organic light-emitting devices (WOLED) with the structures of ITO/m-MTDATA (10 nm)/NPB (30 nm)/Rubrene (0.2 nm)/DOPPP (x nm)/TAz (10 nm)/Alq3 (30 nm)/LiF (0.5 nm)/Al and ITO/NPB (30 nm)/DPAVBi:Rubrene (2 wt.%, 20 nm)/ DOPPP (x nm)/TAZ (10 nm)/Alq3 (30 nm)/LiF (0.5 nm)/Al (100 nm) have been fabricated by the vacuum thermal evaporation method. The results show that the chroma of the non-doped device is the best and the color coordinates are in the range of white light. The maximum luminance is 12,750 cd/m2 and the maximum current efficiency is 8.55 cd/A. The doped device A has the maximum luminance (16,570 cd/m2), when the thickness of blue layer DOPPP is 25 nm, and the doped device B achieves the highest efficiency (10.47 cd/A), when the thickness of DOPPP is 15 nm. All the performances of the doped devices are better than the non-doped one. The results demonstrate that the doped structures can realize the energy transfer and then improve the performance of the device effectively.
17. Next generation of high-efficient waste incinerators. Final report
Energy Technology Data Exchange (ETDEWEB)
Jappe Frandsen, F.
2010-11-15
Modern society produces increasing amounts of combustible waste which may be utilized for heat and power production, at a lower emission of CO{sub 2}, e.g. by substituting a certain fraction of energy from fossil fuel-fired power stations. In 2007, 20.4 % of the district heating and 4.5 % of the power produced in Denmark came from thermal conversion of waste, and waste is a very important part of a future sustainable, and independent, Danish energy supply [Frandsen et al., 2009; Groen Energi, 2010]. In Denmark, approx 3.3 Mtons of waste was produced in 2005, an amount predicted to increase to 4.4 Mtons by the year 2030. According to Affald Danmark, 25 % of the current WtE plant capacity in Denmark is older than 20 years, which is usually considered as the technical and economical lifetime of WtE plants. Thus, there is a need for installation of a significant fraction of new waste incineration capacity, preferentially with an increased electrical efficiency, within the next few years. Compared to fossil fuels, waste is difficult to handle in terms of pre-treatment, combustion, and generation of reusable solid residues. In particular, the content of inorganic species (S, Cl, K, Na, etc.) is problematic, due to enhanced deposition and corrosion - especially at higher temperatures. This puts severe constraints on the electrical efficiency of grate-fired units utilizing waste, which seldom exceeds 26-27%, campared to 46-48 % for coal combustion in suspension. The key parameters when targeting higher electrical efficiency are the pressure and temperature in the steam cycle, which are limited by high-temperature corrosion, boiler- and combustion-technology. This report reviews some of the means that can be applied in order to increase the electrical efficiency in plants firing waste on a grate. (Author)
18. High-efficiency silicon solar cells for low-illumination applications
OpenAIRE
Glunz, S.W.; Dicker, J.; Esterle, M.; Hermle, M.; Isenberg, J.; Kamerewerd, F.; Knobloch, J.; Kray, D.; Leimenstoll, A.; Lutz, F.; Oßwald, D.; Preu, R.; Rein, S.; Schäffer, E.; Schetter, C.
2002-01-01
At Fraunhofer ISE the fabrication of high-efficiency solar cells was extended from a laboratory scale to a small pilot-line production. Primarily, the fabricated cells are used in small high-efficiency modules integrated in prototypes of solar-powered portable electronic devices such as cellular phones, handheld computers etc. Compared to other applications of high-efficiency cells such as solar cars and planes, the illumination densities found in these mainly indoor applications are signific...
19. A novel power source for high-precision, highly efficient micro w-EDM
International Nuclear Information System (INIS)
Chen, Shun-Tong; Chen, Chi-Hung
2015-01-01
The study presents the development of a novel power source for high-precision, highly efficient machining of micropart microstructures using micro wire electrical discharge machining (w-EDM). A novel power source based on a pluri resistance–capacitance (pRC) circuit that can generate a high-frequency, high-peak current with a short pulse train is proposed and designed to enhance the performance of micro w-EDM processes. Switching between transistors is precisely controlled in the designed power source to create a high-frequency short-pulse train current. Various microslot cutting tests in both aluminum and copper alloys are conducted. Experimental results demonstrate that the pRC power source creates instant spark erosion resulting in markedly less material for removal, diminishing discharge crater size, and consequently an improved surface finish. A new evaluation approach for spark erosion ability (SEA) to assess the merits of micro EDM power sources is also proposed. In addition to increasing the speed of micro w-EDM by increasing wire feed rates by 1.6 times the original feed rate, the power source is more appropriate for machining micropart microstructures since there is less thermal breaking. Satisfactory cutting of an elaborate miniature hook-shaped structure and a high-aspect ratio microstructure with a squared-pillar array also reveal that the developed pRC power source is effective, and should be very useful in the manufacture of intricate microparts. (paper)
20. Powerful highly efficient KrF lamps excited by surface and barrier discharges
International Nuclear Information System (INIS)
Borisov, V M; Vodchits, V A; El'tsov, A V; Khristoforov, O B
1998-01-01
An investigation was made of the characteristics of KrF lamps with different types of excitation by surface and barrier discharges in which the dielectric material was sapphire. The conditions were determined for the attainment of an extremely high yield of the KrF* fluorescence with the internal efficiency η in ∼30 % and 22% for pulsed surface and barrier discharges, respectively. A homogeneous surface discharge was maintained without gas circulation when the pulse repetition rate was 5 x 10 4 Hz. Quasicontinuous excitation of a surface discharge at near-atmospheric pressure made it possible to reach a KrF* fluorescence power density of about 80 W cm -3 , which was close to the limit set by the kinetics of the gaseous medium. Under prolonged excitation conditions the intensity of the UV output radiation was limited by the permissible heating of the gas to a temperature above which the operating life of the gaseous mixture containing fluorine fell steeply. This was the reason for the advantage of surface over barrier discharges: the former were characterised by a high thermal conductivity of a thin (∼0.2 mm) plasma layer on the surface of the cooled dielectric, which made it possible to construct powerful highly efficient KrF and ArF lamps emitting UV radiation of up to 1 W cm -2 intensity. (laser system components)
1. Completion of high-efficiency BWR turbine plant 'Hamaoka unit No. 4'
International Nuclear Information System (INIS)
Tsuji, Kunio; Hamaura, Norikazu; Shibashita, Naoaki; Kazama, Seiichi
1995-01-01
Accompanying the increase of capacity of nuclear power plants in Japan, the plants having heightened economical efficiency, which are supported by the improvement of thermal efficiency and the reduction of dose, are demanded. Hitachi Ltd. has completed No. 4 turbine unit of 1137 MW output in Hamaoka Nuclear Power Station, Chubu Electric Power Co., Inc., which is the largest capacity machine in Japanese BWR plants. In this unit, the moisture separator heater, the steam turbine with high efficiency, and the hollow thread film condensate filter which treats the total flow rate of condensate are used as the reheating type BWR plant for the first time in Japan, and the plan of heightened economy and operation was adopted. It was confirmed by the trial for about 10 months that the planned performance was sufficiently satisfied, and the commercial operation was started in September, 1993. The features of the 1137 MW turbine unit are explained. The turbine is of tandem six-flow exhaust condensation type. Diffuser type low pressure turbine exhaust chambers, butterfly type combination intermediate valve are adopted. The stages with the blades having moisture-separating grooves were corrected. The reliability of the shaft system was improved. The adoption of the moisture separator heater and the application of the hollow thread film type condensate filter are explained. (K.I.)
2. New results of development on high efficiency high gradient superconducting rf cavities
Energy Technology Data Exchange (ETDEWEB)
Geng, Rongli [Thomas Jefferson National Accelerator Facility, Newport News, VA (United States); Li, Z. K. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Hao, Z. K. [Peking Univ., Beijing (China); Liu, K. X. [Peking Univ., Beijing (China); Zhao, H. Y. [OTIC, Ningxia (China); Adolphsen, C. [SLAC National Accelerator Lab., Menlo Park, CA (United States)
2015-09-01
We report on the latest results of development on high-efficiency high-gradient superconducting radio frequency (SRF) cavities. Several 1-cell cavities made of large-grain niobium (Nb) were built, processed and tested. Two of these cavities are of the Low Surface Field (LSF) shape. Series of tests were carried out following controlled thermal cycling. Experiments toward zero-field cooling were carried out. The best experimentally achieved results are Eacc = 41 MV/m at Q0 = 6.5×1010 at 1.4 K by a 1-cell 1.3 GHz large-grain Nb TTF shape cavity and Eacc = 49 MV/m at Q0 = 1.5×1010 at 1.8 K by a 1-cell 1.5 GHz large-grain Nb CEBAF upgrade low-loss shape cavity.
3. Design and development of a high efficiency tank for crude oil dehydration (i)
International Nuclear Information System (INIS)
Forero, Jorge Enrique; Ortiz Olga Patricia; Narino, Fredy Abelardo
2008-01-01
This paper introduces a new tank design for dehydrating and desalting large volumes of crude oils previously degasified, crude oil dehydration efficiency is reduced by gas presence in the emulsion interphase. The design presented in this paper is versatile (it is adaptable to any classical dehydration process), highly efficient in terms of separation (values usually greater than 90% and/or treated crude oil BSW less than 0,5% are ensured), low installation and operation costs, less consumption of additives. These are some of the advantages found in pilot tests plants and proven in industrial systems at the ECOPETROL S.A. production fields with treatment capacities from 14 to 50 KBD. Although this process also can be applied to other ranks of flow, maintaining the design critical conditions of each case in particular. This system does not exhibit the typical limitations shown by treatment traditional systems (FWKO, Gun Barrel, thermal and electrostatic separators, etc.) (Al-Ghamdi, 2007) since it can be easily adapted to system treatments for light, intermediate, and heavy crude oils and to treatments with BSW content ranging from a very low levels of ≤ 1% to very high levels ≥ 95%, values that are not unusual in production fields nowadays, especially where accelerated production methods are used
4. Progress in target materials for high-efficiency X-ray backlight
International Nuclear Information System (INIS)
Du Ai; Zhou Bin; Li Longxiang; Zhu Xiurong; Li Yu'nong; Shen Jun; Gao Guohua; Zhang Zhihua; Wu Guangming
2012-01-01
The composition, microstructure and density of the target materials are the key parameters to determinate the photon energy and intensity of the laser-induced X-ray backlight. Thus the classification of backlight targets, the preparation of target materials and the interaction between targets and high power laser were introduced in this paper. Underdense targets were more competitive than traditional dense targets among the backlight targets. Nano-structured foam targets, which could be classified into nanofiber targets and aerogel targets, were regarded as novel high-efficiency underdense targets. Nanofiber, which was commonly prepared via electro spinning and thermal treatment, exhibited good formability and high concentration of emission atoms; while aerogel, which was prepared via sol-gel processes and supercritical fluid drying, possesses the advantages of homogeneous microstructure and theoretically high conversion efficiency, but accompanied with the disadvantages of complex synthetic processes and low concentration of emission atoms. To prepare monolithic aerogels with low density and high concentration of emission atoms via combined sol-gel theories may be the better design for the development of the laser-induced X-ray backlight. (authors)
5. Completion of a high efficiency ultralarge capacity three-phase transformer
International Nuclear Information System (INIS)
Maejima, Masaaki; Maruyama, Katsuya; Fukuda, Teruo.
1986-01-01
As for the boosting transformers for thermal and nuclear power stations, at present the ultralarge capacity transformers of 1000 - 1200 MVA class are the main, and particularly in nuclear power, accompanying the development of improved type BWRs and the rise of system stability, there is the tendency toward further large capacity and large size. Consequently, reflecting the recent rise of energy cost, the demand of energy conservation and the reduction of required sites heightened largely as well as the high reliability. In order to meet these demands, Hitachi Ltd. has established the technology of changing to iron machines such as ultralarge iron cores and ultralarge capacity undivided disk windings using the latest design and manufacture techniques were applied to the 525 kV, 1200 MVA transformer for No.4 plant in Fukushima No.2 Nuclear Power Station, Tokyo Electric Power Co., Inc., thus a three-phase transformer of the highest level, high efficiency and ultralarge capacity was completed. In this paper, the outline of this transformer and the test for verifying its reliability are described. The technical change of large capacity three-phase transformers, the specifications, construction, manufacture, reliability test and the effect of modification of this transformer, and the expansion of application to the next generation ultralarge capacity transformers are reported. (Kako, I.)
6. Thermal ionization mass spectrometry (TIMS) of actinides: Pushing the limits of accuracy and detection
Energy Technology Data Exchange (ETDEWEB)
Buerger, Stefan; Boulyga, Sergei; Cunningham, Alan; Klose, Dilani; Koepf, Andreas; Poths, Jane [Safeguards Analytical Laboratory, International Atomic Energy Agency, Vienna (Austria); Richter, Stephan [Institute for Reference Materials and Measurements, JRC-EU, Geel (Belgium)
2010-07-01
New method developments in multi-collector thermal ionization mass spectrometry (MC-TIMS) for actinide isotope ratio analysis to improve accuracy and limits of detection will be presented. With respect to limits of detection, results on improving work function using various carbon additives will be reviewed and presented as well as developments in cavity ion source (as compared to standard flat ribbon filament ion source) for femto- and attogram levels of uranium, plutonium, and americium. With respect to accuracy, results on isotope ratio measurements of isotopes of uranium (relative accuracy of 0.3% to 0.01%) are presented with an example being U-234-Th-230 age-dating (NBL CRM 112-A). In this context, the importance of traceability (to the S.I. units) and the use of (certified) reference materials are emphasized. The focus of this presentation is on applications to nuclear safeguards / forensics.
7. Second Generation Advanced Reburning for High Efficiency NOx Control
Energy Technology Data Exchange (ETDEWEB)
Vladimir M. Zamansky; Peter M. Maly; Vitali V. Lissianski; Mark S. Sheldon; David Moyeda; Roy Payne
2001-06-30
viability of the AR technology. The performance goals of the project to reduce NO{sub x} by up to 95% with net emissions less than 0.06 lb/10{sup 6} Btu and to minimize other pollutants (N{sub 2}O and NH{sub 3}) to levels lower than reburning and SNCR have been met. Experimental data demonstrated that AR-Lean + SNCR and Reburning + SNCR are the most effective AR configurations, followed by AR-Lean and AR-Rich. Promoters can increase AR NO{sub x} reduction efficiency. Promoters are the most effective at small amounts of the reburning fuel (6-10% of the total fuel heat input). Promoters provide the means to improve NO{sub x} reduction and simultaneously decrease the amount of reburning fuel. Tests also showed that alkali-containing compounds are effective promoters of the AR process. When co-injected with N-agent, they provide up to 25 % improvement in NO{sub x} reduction. A detailed reaction mechanism and simplified representation of mixing were used in modeling of AR processes. Modeling results demonstrated that the model correctly described a wide range of experimental data. Mixing and thermal parameters in the model can be adjusted depending on characteristics of the combustion facility. Application of the model to the optimization of AR-Lean has been demonstrated. Economic analysis demonstrated a considerable economic advantage of AR technologies in comparison with existing commercial NO{sub x} control techniques, such as basic reburning, SNCR, and SCR. Particularly for deep NO{sub x} control, coal-based AR technologies are 50% less expansive than SCR for the same level of NO{sub x} control. The market for AR technologies is estimated to be above $110 million. 8. High Efficiency Nanostructured III-V Photovoltaics for Solar Concentrator Application Energy Technology Data Exchange (ETDEWEB) Hubbard, Seth 2012-09-12 The High Efficiency Nanostructured III-V Photovoltaics for Solar Concentrators project seeks to provide new photovoltaic cells for Concentrator Photovoltaics (CPV) Systems with higher cell efficiency, more favorable temperature coefficients and less sensitivity to changes in spectral distribution. The main objective of this project is to provide high efficiency III-V solar cells that will reduce the overall cost per Watt for power generation using CPV systems.This work is focused both on a potential near term application, namely the use of indium arsenide (InAs) QDs to spectrally "tune" the middle (GaAs) cell of a SOA triple junction device to a more favorable effective bandgap, as well as the long term goal of demonstrating intermediate band solar cell effects. The QDs are confined within a high electric field i-region of a standard GaAs solar cell. The extended absorption spectrum (and thus enhanced short circuit current) of the QD solar cell results from the increase in the sub GaAs bandgap spectral response that is achievable as quantum dot layers are introduced into the i-region. We have grown InAs quantum dots by OMVPE technique and optimized the QD growth conditions. Arrays of up to 40 layers of strain balanced quantum dots have been experimentally demonstrated with good material quality, low residual stain and high PL intensity. Quantum dot enhanced solar cells were grown and tested under simulated one sun AM1.5 conditions. Concentrator solar cells have been grown and fabricated with 5-40 layers of QDs. Testing of these devices show the QD cells have improved efficiency compared to baseline devices without QDs. Device modeling and measurement of thermal properties were performed using Crosslight APSYS. Improvements in a triple junction solar cell with the insertion of QDs into the middle current limiting junction was shown to be as high as 29% under one sun illumination for a 10 layer stack QD enhanced triple junction solar cell. QD devices have strong 9. Standardization on the specification, test and evaluation of high efficiency motors and inverters Energy Technology Data Exchange (ETDEWEB) Kim, Kil Yong [Korea Electric Power Corp. (KEPCO), Taejon (Korea, Republic of). Research Center; Hyun, Chang Soon [Korea Academy of Industrial Technology, Incheon (Korea, Republic of) 1995-12-31 Most of the power systems energy is consumed by electrical motors. This report proposes a method for the standardization on the specification, test and evaluation of the high efficiency motors and related inverters. The results of this report can be referred to the rebate program for promoting the use of high efficiency motors and inverters (author). 26 refs., 102 figs. 10. Highly efficient red phosphorescent organic light-emitting diodes based on solution processed emissive layer International Nuclear Information System (INIS) Liu, Baiquan; Xu, Miao; Tao, Hong; Ying, Lei; Zou, Jianhua; Wu, Hongbin; Peng, Junbiao 2013-01-01 Highly efficient red phosphorescent organic polymer light-emitting diodes (PhOLEDs) were fabricated based on a solution-processed small-molecule host 4,4′-bis(N-carbazolyl)-1,1′-biphenyl (CBP) by doping an iridium complex, tris(1-(2,6-dimethylphenoxy)-4-(4-chlorophenyl)phthalazine)iridium (III) (Ir(MPCPPZ) 3 ). A hole blocking layer 1,3,5-tri(1-phenyl-1H-benzo[d]imidazol-2-yl)phenyl (TPBI) with a function of electron transport was thermally deposited onto the top of CBP layer. The diode with the structure of ITO/PEDOT:PSS (50 nm)/CBP:Ir(MPCPPZ) 3 (55 nm)/TPBI (30 nm)/Ba (4 nm)/Al (120 nm) showed an external quantum efficiency (QE ext ) of 19.3% and luminous efficiency (LE) of 18.3 cd/A at a current density of 0.16 mA/cm 2 , and Commission International de I'Eclairage (CIE) coordinates of (0.607, 0.375). It was suggested that the diodes using TPBI layer exhibited nearly 100% internal quantum efficiency and one order magnitude enhanced LE or QE ext efficiencies. -- Highlights: • Efficient red PhOLEDs based on a solution-processed small-molecule host were fabricated. • By altering volume ratio of chloroform/chlorobenzene solvent, we got best film quality of CBP. • EQE of the diode was 19.3%, indicating nearly 100% internal quantum yield was achieved 11. High Efficiency Thermionics (HET-IV) and Converter Advancement (CAP) programs. Final reports Energy Technology Data Exchange (ETDEWEB) Geller, C.B.; Murray, C.S.; Riley, D.R. [Bettis Atomic Power Lab., West Mifflin, PA (United States); Desplat, J.L.; Hansen, L.K.; Hatch, G.L.; McVey, J.B.; Rasor, N.S. [Rasor Associates, Inc., Sunnyvale, CA (United States) 1996-04-01 This report contains the final report of the High Efficiency Thermionics (HET-IV) Program, Attachment A, performed at Rasor Associates, Inc. (RAI); and the final report of the Converter Advancement Program (CAP), performed at the Bettis Atomic Power Laboratory, Attachment B. The phenomenology of cesium-oxygen thermionic converters was elucidated in these programs, and the factors that had prevented the achievement of stable, enhanced cesium-oxygen converter performance for the previous thirty years were identified. Based on these discoveries, cesium-oxygen vapor sources were developed that achieved stable performance with factor-of-two improvements in power density and thermal efficiency, relative to conventional, cesium-only ignited mode thermionic converters. Key achievements of the HET-IV/CAP programs are as follows: a new technique for measuring minute traces of oxygen in cesium atmospheres; the determination of the proper range of oxygen partial pressures for optimum converter performance--10{sup {minus}7} to 10{sup {minus}9} torr; the discovery, and analysis of the cesium-oxygen liquid migration and compositional segregation phenomena; the successful use of capillary forces to contain the migration phenomenon; the use of differential heating to control compositional segregation, and induce vapor circulation; the development of mechanically and chemically stable, porous reservoir structures; the development of precise, in situ oxygen charging methods; stable improvements in emitter performance, up to effective emitter bare work functions of 5.4 eV; stable improvements in barrier index, to value below 1.8 Volts; the development of detailed microscopic models for cesium-oxygen reservoir dynamics and collector work function behavior; and the discovery of new relationships between electrode geometry and Schock Instability. 12. High-efficiency cavity-dumped micro-chip Yb:YAG laser Science.gov (United States) Nishio, M.; Maruko, A.; Inoue, M.; Takama, M.; Matsubara, S.; Okunishi, H.; Kato, K.; Kyomoto, K.; Yoshida, T.; Shimabayashi, K.; Morioka, M.; Inayoshi, S.; Yamagata, S.; Kawato, S. 2014-09-01 High-efficiency cavity-dumped ytterbium-doped yttrium aluminum garnet (Yb:YAG) laser was developed. Although the high quantum efficiency of ytterbium-doped laser materials is appropriate for high-efficiency laser oscillation, the efficiency is decreased by their quasi-three/four laser natures. High gain operation by high intensity pumping is suitable for high efficiency oscillation on the quasi-three/four lasers without extremely low temperature cooling. In our group, highest efficiency oscillations for continuous wave, nanosecond to picosecond pulse lasers were achieved at room temperature by the high gain operation in which pump intensities were beyond 100 kW/cm2. 13. Innovative Ultra-High Efficiency Cryogenic Actuators for Rocket Test Facilities, Phase I Data.gov (United States) National Aeronautics and Space Administration — The SBIR Phase I project will develop advanced ultra-high efficiency cryogenic actuators for NASA cryogenic fluid transfer application. The actuator will have low... 14. Ultra-Lightweight High Efficiency Nanostructured Materials and Coatings for Deep Space Mission Environments, Phase II Data.gov (United States) National Aeronautics and Space Administration — NanoSonic has developed a nanostructured spray self-assembly manufacturing method that has resulted in ultra-lightweight ( 1000%), and multi-layer, high efficiency... 15. Qualitative and quantitative determination of ubiquinones by the method of high-efficiency liquid chromatography International Nuclear Information System (INIS) Yanotovskii, M.T.; Mogilevskaya, M.P.; Obol'nikova, E.A.; Kogan, L.M.; Samokhvalov, G.I. 1986-01-01 A method has been developed for the qualitative and quantitative determination of ubiquinones CoQ 6 -CoQ 10 , using high-efficiency reversed-phase liquid chromatography. Tocopherol acetate was used as the internal standard 16. Development of a Robust, Highly Efficient Oxygen-Carbon Monoxide Cogeneration System, Phase I Data.gov (United States) National Aeronautics and Space Administration — This small business innovation research is intended to develop a long-life, highly efficient O2-CO cogeneration system to support NASA's endeavors to pursue... 17. Ultra-Lightweight, High Efficiency Silicon-Carbide (SIC) Based Power Electronic Converters, Phase I Data.gov (United States) National Aeronautics and Space Administration — This Small Business of Innovation Research Phase I proposal seeks to investigate and prove the feasibility of developing highly efficient, ultra-lightweight SiC... 18. Highly Efficient Closed-Loop CO2 Removal System for Deep-Space ECLSS, Phase I Data.gov (United States) National Aeronautics and Space Administration — TDA Research Inc.(TDA) in collaboration with University of Puerto Rico ? Mayaguez (UPRM is proposing to develop a highly efficient CO2 removal system based on UPRM... 19. MMIC for High-Efficiency Ka-BAnd GaN Power Amplifiers (2007043), Phase I Data.gov (United States) National Aeronautics and Space Administration — This proposal addresses the need for high-efficiency, high-output power amplifiers operating in the Ka-band frequencies. For space communications, the power... 20. High Efficiency Advanced Lightweight Fuel Cell (HEAL-FC), Phase I Data.gov (United States) National Aeronautics and Space Administration — Infinity's High Efficiency Advanced Lightweight Fuel Cell (HEAL FC) is an improved version of its current fuel cell technology developed for space applications. The... 1. High Efficiency Quantum Dot III-V Multijunction Solar Cell for Space Power, Phase II Data.gov (United States) National Aeronautics and Space Administration — We are proposing to utilize quantum dots to develop a super high-efficiency multijunction III-V solar cell for space. In metamorphic triple junction space solar... 2. High Efficiency, High Temperature Foam Core Heat Exchanger for Fission Surface Power Systems, Phase II Data.gov (United States) National Aeronautics and Space Administration — Fission-based power systems with power levels of 30 to ≥100 kWe will be needed for planetary surface bases. Development of high temperature, high efficiency heat... 3. A 380 V High Efficiency and High Power Density Switched-Capacitor Power Converter using Wide Band Gap Semiconductors DEFF Research Database (Denmark) Fan, Lin; Knott, Arnold; Jørgensen, Ivan Harald Holger 2018-01-01 . This paper presents such a high voltage low power switched-capacitor DC-DC converter with an input voltage upto 380 V (compatible with rectified European mains) and an output power experimentally validated up to 21.3 W. The wideband gap semiconductor devices of GaN switches and SiC diodes are combined...... to compose the proposed power stage. Their switching and loss characteristics are analyzed with transient waveforms and thermal images. Different isolated driving circuits are compared and a compact isolated halfbridge driving circuit is proposed. The full-load efficiencies of 98.3% and 97.6% are achieved......State-of-the-art switched-capacitor DC-DC power converters mainly focus on low voltage and/or high power applications. However, at high voltage and low power levels, new designs are anticipated to emerge and a power converter that has both high efficiency and high power density is highly desirable... 4. Study on highly efficient seismic data acquisition and processing methods based on sparsity constraint Science.gov (United States) Wang, H.; Chen, S.; Tao, C.; Qiu, L. 2017-12-01 High-density, high-fold and wide-azimuth seismic data acquisition methods are widely used to overcome the increasingly sophisticated exploration targets. The acquisition period is longer and longer and the acquisition cost is higher and higher. We carry out the study of highly efficient seismic data acquisition and processing methods based on sparse representation theory (or compressed sensing theory), and achieve some innovative results. The theoretical principles of highly efficient acquisition and processing is studied. We firstly reveal sparse representation theory based on wave equation. Then we study the highly efficient seismic sampling methods and present an optimized piecewise-random sampling method based on sparsity prior information. At last, a reconstruction strategy with the sparsity constraint is developed; A two-step recovery approach by combining sparsity-promoting method and hyperbolic Radon transform is also put forward. The above three aspects constitute the enhanced theory of highly efficient seismic data acquisition. The specific implementation strategies of highly efficient acquisition and processing are studied according to the highly efficient acquisition theory expounded in paragraph 2. Firstly, we propose the highly efficient acquisition network designing method by the help of optimized piecewise-random sampling method. Secondly, we propose two types of highly efficient seismic data acquisition methods based on (1) single sources and (2) blended (or simultaneous) sources. Thirdly, the reconstruction procedures corresponding to the above two types of highly efficient seismic data acquisition methods are proposed to obtain the seismic data on the regular acquisition network. A discussion of the impact on the imaging result of blended shooting is discussed. In the end, we implement the numerical tests based on Marmousi model. The achieved results show: (1) the theoretical framework of highly efficient seismic data acquisition and processing 5. High Efficiency Heat Exchanger for High Temperature and High Pressure Applications Energy Technology Data Exchange (ETDEWEB) Sienicki, James J. [Argonne National Lab. (ANL), Argonne, IL (United States). Nuclear Engineering Division; Lv, Qiuping [Argonne National Lab. (ANL), Argonne, IL (United States). Nuclear Engineering Division; Moisseytsev, Anton [Argonne National Lab. (ANL), Argonne, IL (United States). Nuclear Engineering Division 2017-09-29 CompRex, LLC (CompRex) specializes in the design and manufacture of compact heat exchangers and heat exchange reactors for high temperature and high pressure applications. CompRex’s proprietary compact technology not only increases heat exchange efficiency by at least 25 % but also reduces footprint by at least a factor of ten compared to traditional shell-and-tube solutions of the same capacity and by 15 to 20 % compared to other currently available Printed Circuit Heat Exchanger (PCHE) solutions. As a result, CompRex’s solution is especially suitable for Brayton cycle supercritical carbon dioxide (sCO2) systems given its high efficiency and significantly lower capital and operating expenses. CompRex has already successfully demonstrated its technology and ability to deliver with a pilot-scale compact heat exchanger that was under contract by the Naval Nuclear Laboratory for sCO2 power cycle development. The performance tested unit met or exceeded the thermal and hydraulic specifications with measured heat transfer between 95 to 98 % of maximum heat transfer and temperature and pressure drop values all consistent with the modeled values. CompRex’s vision is to commercialize its compact technology and become the leading provider for compact heat exchangers and heat exchange reactors for various applications including Brayton cycle sCO2 systems. One of the limitations of the sCO2 Brayton power cycle is the design and manufacturing of efficient heat exchangers at extreme operating conditions. Current diffusion-bonded heat exchangers have limitations on the channel size through which the fluid travels, resulting in excessive solid material per heat exchanger volume. CompRex’s design allows for more open area and shorter fluid proximity for increased heat transfer efficiency while sustaining the structural integrity needed for the application. CompRex is developing a novel improvement to its current heat exchanger design where fluids are directed to alternating 6. Streptavidin-functionalized capillary immune microreactor for highly efficient chemiluminescent immunoassay Energy Technology Data Exchange (ETDEWEB) Yang Zhanjun [State Key Laboratory of Analytical Chemistry for Life Science, Department of Chemistry, Nanjing University, Nanjing 210093 (China); College of Chemistry and Engineering, Yangzhou University, 88 South University Avenue, Yangzhou 225002 (China); Zong Chen [State Key Laboratory of Analytical Chemistry for Life Science, Department of Chemistry, Nanjing University, Nanjing 210093 (China); Ju Huangxian, E-mail: hxju@nju.edu.cn [State Key Laboratory of Analytical Chemistry for Life Science, Department of Chemistry, Nanjing University, Nanjing 210093 (China); Yan Feng, E-mail: yanfeng2007@sohu.com [Jiangsu Institute of Cancer Prevention and Cure, Nanjing 210009 (China) 2011-11-07 Highlights: {yields} A novel capillary immune microreactor was proposed for highly efficient flow-through chemiluminescent immunoassay. {yields} The microreactor was prepared by functionalizing capillary inner wall with streptavidin for capture of biotinylated antibody. {yields} The proposed immunoassay method showed wide dynamic range, good reproducibility, stability and practicality. {yields} The microreactor was low-cost and disposable, and possessed several advantages over the conventional immunoreactors. - Abstract: A streptavidin functionalized capillary immune microreactor was designed for highly efficient flow-through chemiluminescent (CL) immunoassay. The functionalized capillary could be used as both a support for highly efficient immobilization of antibody and a flow cell for flow-through immunoassay. The functionalized inner wall and the capture process were characterized using scanning electron microscopy. Compared to conventional packed tube or thin-layer cell immunoreactor, the proposed microreactor showed remarkable properties such as lower cost, simpler fabrication, better practicality and wider dynamic range for fast CL immunoassay with good reproducibility and stability. Using {alpha}-fetoprotein as model analyte, the highly efficient CL flow-through immunoassay system showed a linear range of 3 orders of magnitude from 0.5 to 200 ng mL{sup -1} and a low detection limit of 0.1 ng mL{sup -1}. The capillary immune microreactor could make up the shortcoming of conventional CL immunoreactors and provided a promising alternative for highly efficient flow-injection immunoassay. 7. Ultra-high Efficiency DC-DC Converter using GaN Devices DEFF Research Database (Denmark) Ramachandran, Rakesh 2016-01-01 properties of GaN devices can be utilized in power converters to make them more compact and highly efficient. This thesis entitled “Ultra-high Efficiency DC-DC Converter using GaN devices” focuses on achieving ultra-high conversion efficiency in an isolated dc-dc converter by the optimal utilization of Ga...... for many decades. However, the rate of improvement slowed as the silicon power materials asymptotically approached its theoretical bounds. Compared to Si, wideband gap materials such as Silicon Carbide (SiC) and Gallium Nitride (GaN) are promising semiconductors for power devices due to their superior...... in this thesis. Efficiency measurements from the hardware prototype of both the topologies are also presented in this thesis. Finally, the bidirectional operation of an optimized isolated dc-dc converter is presented. The optimized converter has achieved an ultra-high efficiency of 98.8% in both directions... 8. High voltage generator circuit with low power and high efficiency applied in EEPROM International Nuclear Information System (INIS) Liu Yan; Zhang Shilin; Zhao Yiqiang 2012-01-01 This paper presents a low power and high efficiency high voltage generator circuit embedded in electrically erasable programmable read-only memory (EEPROM). The low power is minimized by a capacitance divider circuit and a regulator circuit using the controlling clock switch technique. The high efficiency is dependent on the zero threshold voltage (V th ) MOSFET and the charge transfer switch (CTS) charge pump. The proposed high voltage generator circuit has been implemented in a 0.35 μm EEPROM CMOS process. Measured results show that the proposed high voltage generator circuit has a low power consumption of about 150.48 μW and a higher pumping efficiency (83.3%) than previously reported circuits. This high voltage generator circuit can also be widely used in low-power flash devices due to its high efficiency and low power dissipation. (semiconductor integrated circuits) 9. Broadband and high-efficiency vortex beam generator based on a hybrid helix array. Science.gov (United States) Fang, Chaoqun; Wu, Chao; Gong, Zhijie; Zhao, Song; Sun, Anqi; Wei, Zeyong; Li, Hongqiang 2018-04-01 The vortex beam which carries the orbital angular momentum has versatile applications, such as high-resolution imaging, optical communications, and particle manipulation. Generating vortex beams with the Pancharatnam-Berry (PB) phase has drawn considerable attention for its unique spin-to-orbital conversion features. Despite the PB phase being frequency independent, an optical element with broadband high-efficiency circular polarization conversion feature is still needed for the broadband high-efficiency vortex beam generation. In this work, a broadband and high-efficiency vortex beam generator based on the PB phase is built with a hybrid helix array. Such devices can generate vortex beams with arbitrary topological charge. Moreover, vortex beams with opposite topological charge can be generated with an opposite handedness incident beam that propagates backward. The measured efficiency of our device is above 65% for a wide frequency range, with the relative bandwidth of 46.5%. 10. High quality ceramic coatings sprayed by high efficiency hypersonic plasma spraying gun International Nuclear Information System (INIS) Zhu Sheng; Xu Binshi; Yao JiuKun 2005-01-01 This paper introduced the structure of the high efficiency hypersonic plasma spraying gun and the effects of hypersonic plasma jet on the sprayed particles. The optimised spraying process parameters for several ceramic powders such as Al 2 O 3 , Cr 2 O 3 , ZrO 2 , Cr 3 C 2 and Co-WC were listed. The properties and microstructure of the sprayed ceramic coatings were investigated. Nano Al 2 O 3 -TiO 2 ceramic coating sprayed by using the high efficiency hypersonic plasma spraying was also studied. Compared with the conventional air plasma spraying, high efficiency hypersonic plasma spraying improves greatly the ceramic coatings quality but at low cost. (orig.) 11. Review of status developments of high-efficiency crystalline silicon solar cells Science.gov (United States) Liu, Jingjing; Yao, Yao; Xiao, Shaoqing; Gu, Xiaofeng 2018-03-01 In order to further improve cell efficiency and reduce cost in achieving grid parity, a large number of PV manufacturing companies, universities and research institutes have been devoted to a variety of low-cost and high-efficiency crystalline Si solar cells. In this article, the cell structures, characteristics and efficiency progresses of several types of high-efficiency crystalline Si solar cells that have been in small scale production or are promising in mass production are presented, including passivated emitter rear cell, tunnel oxide passivated contact solar cell, interdigitated back contact cell, heterojunction with intrinsic thin-layer cell, and heterojunction solar cells with interdigitated back contacts. Both the industrialization status and future development trend of high-efficiency crystalline silicon solar cells are also pinpointed. 12. Fundamental understanding and development of low-cost, high-efficiency silicon solar cells Energy Technology Data Exchange (ETDEWEB) ROHATGI,A.; NARASIMHA,S.; MOSCHER,J.; EBONG,A.; KAMRA,S.; KRYGOWSKI,T.; DOSHI,P.; RISTOW,A.; YELUNDUR,V.; RUBY,DOUGLAS S. 2000-05-01 The overall objectives of this program are (1) to develop rapid and low-cost processes for manufacturing that can improve yield, throughput, and performance of silicon photovoltaic devices, (2) to design and fabricate high-efficiency solar cells on promising low-cost materials, and (3) to improve the fundamental understanding of advanced photovoltaic devices. Several rapid and potentially low-cost technologies are described in this report that were developed and applied toward the fabrication of high-efficiency silicon solar cells. 13. A High Efficiency Li-Ion Battery LDO-Based Charger for Portable Application Directory of Open Access Journals (Sweden) Youssef Ziadi 2015-01-01 Full Text Available This paper presents a high efficiency Li-ion battery LDO-based charger IC which adopted a three-mode control: trickle constant current, fast constant current, and constant voltage modes. The criteria of the proposed Li-ion battery charger, including high accuracy, high efficiency, and low size area, are of high importance. The simulation results provide the trickle current of 116 mA, maximum charging current of 448 mA, and charging voltage of 4.21 V at the power supply of 4.8–5 V, using 0.18 μm CMOS technology. 14. High-efficiency FEL with Bragg resonator driven by linear induction accelerator Energy Technology Data Exchange (ETDEWEB) Ginzburg, N S; Kaminskij, A A; Kaminskij, A K; Peskov, N Yu; Sedykh, S N; Sergeev, A P; Sergeev, A S [Russian Academy of Sciences, Nizhny Novgorod (Russian Federation). Inst. of Applied Physics 1997-12-31 A narrow-band high-efficiency FEL-oscillator with a Bragg resonator was constructed based on a linear induction accelerator which formed a 1 MeV, 200 A, 200 ns electron beam. At the frequency of 31 GHz, radiation with a power of 31 MW and efficiency of 25% was measured. A high efficiency and a narrow width of the spectrum were achieved owing to the selective properties of the Bragg resonator in combination with the high quality of the helical electron beam formed in the reversed guide field regime. (author). 3 figs., 3 refs. 15. A novel highly efficient grating coupler with large filling factor used for optoelectronic integration International Nuclear Information System (INIS) Zhou Liang; Li Zhi-Yong; Zhu Yu; Li Yun-Tao; Yu Yu-De; Yu Jin-Zhong; Fan Zhong-Cao; Han Wei-Hua 2010-01-01 A novel highly efficient grating coupler with large filling factor and deep etching is proposed in silicon-on-insulator for near vertical coupling between the rib waveguide and optical fibre. The deep slots acting as high efficient scattering centres are analysed and optimized. As high as 60% coupling efficiency at telecom wavelength of 1550-nm and 3-dB bandwidth of 61 nm are predicted by simulation. A peak coupling efficiency of 42.1% at wavelength 1546-nm and 3-dB bandwidth of 37.6 nm are obtained experimentally. (classical areas of phenomenology) 16. A facile strategy for the fabrication of a bioinspired hydrophilic-superhydrophobic patterned surface for highly efficient fog-harvesting KAUST Repository Wang, Yuchao 2015-08-10 Fog water collection represents a meaningful effort in the places where regular water sources, including surface water and ground water, are scarce. Inspired by the amazing fog water collection capability of Stenocara beetles in the Namib Desert and based on the recent work in biomimetic water collection, this work reported a facile, easy-to-operate, and low-cost method for the fabrication of hydrophilic-superhydrophobic patterned hybrid surface toward highly efficient fog water collection. The essence of the method is incorporating a (super)hydrophobically modified metal-based gauze onto the surface of a hydrophilic polystyrene (PS) flat sheet by a simple lab oven-based thermal pressing procedure. The produced hybrid patterned surfaces consisted of PS patches sitting within the holes of the metal gauzes. The method allows for an easy control over the pattern dimension (e.g., patch size) by varying gauze mesh size and thermal pressing temperature, which is then translated to an easy optimization of the ultimate fog water collection efficiency. Given the low-cost and wide availability of both PS and metal gauze, this method has a great potential for scaling-up. The results showed that the hydrophilic-superhydrophobic patterned hybrid surfaces with a similar pattern size to Stenocara beetles’s back pattern produced significantly higher fog collection efficiency than the uniformly (super)hydrophilic or (super)hydrophobic surfaces. This work contributes to general effort in fabricating wettability patterned surfaces and to atmospheric water collection for direct portal use. 17. Development of a highly efficient indigo dyeing method using indican with an immobilized beta-glucosidase from Aspergillus niger. Science.gov (United States) Song, Jingyuan; Imanaka, Hiroyuki; Imamura, Koreyoshi; Kajitani, Kouichi; Nakanishi, Kazuhiro 2010-09-01 A highly efficient method for dyeing textiles with indigo is described. In this method, the substrate, indican is first hydrolyzed at an acidic pH of 3 using an immobilized beta-glucosidase to produce indoxyl, under which conditions indigo formation is substantially repressed. The textile sample is then dipped in the prepared indoxyl solution and the textile is finally exposed to ammonia vapor for a short time, resulting in rapid indigo dyeing. As an enzyme, we selected a beta-glucosidase from Aspergillus niger, which shows a high hydrolytic activity towards indican and was thermally stable at temperatures up to 50-60 degrees C, in an acidic pH region. The A. niger beta-glucosidase, when immobilized on Chitopearl BCW-3001 by treatment with glutaraldehyde, showed an optimum reaction pH similar to that of the free enzyme with a slightly higher thermal stability. The kinetics for the hydrolysis of indican at pH 3, using the purified free and immobilized enzymes was found to follow Michaelis-Menten type kinetics with weak competitive inhibition by glucose. Using the immobilized enzyme, we successfully carried out repeated-batch and continuous hydrolyses of indican at pH 3 when nitrogen gas was continuously supplied to the substrate solution. Various types of model textiles were dyed using the proposed method although the color yield varied, depending on the type of textile used. Copyright 2010 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved. 18. A highly efficient pricing method for European-style options based on Shannon wavelets NARCIS (Netherlands) L. Ortiz Gracia (Luis); C.W. Oosterlee (Cornelis) 2017-01-01 textabstractIn the search for robust, accurate and highly efficient financial option valuation techniques, we present here the SWIFT method (Shannon Wavelets Inverse Fourier Technique), based on Shannon wavelets. SWIFT comes with control over approximation errors made by means of sharp quantitative 19. A Highly Efficient Shannon Wavelet Inverse Fourier Technique for Pricing European Options NARCIS (Netherlands) Ortiz-Gracia, Luis; Oosterlee, C.W. 2016-01-01 In the search for robust, accurate, and highly efficient financial option valuation techniques, we here present the SWIFT method (Shannon wavelets inverse Fourier technique), based on Shannon wavelets. SWIFT comes with control over approximation errors made by means of sharp quantitative error 20. A highly efficient Shannon wavelet inverse Fourier technique for pricing European options NARCIS (Netherlands) L. Ortiz Gracia (Luis); C.W. Oosterlee (Cornelis) 2016-01-01 htmlabstractIn the search for robust, accurate, and highly efficient financial option valuation techniques, we here present the SWIFT method (Shannon wavelets inverse Fourier technique), based on Shannon wavelets. SWIFT comes with control over approximation errors made by means of 1. High Efficiency Non-isolated Three Port DC-DC Converter for PV-Battery Systems DEFF Research Database (Denmark) Tomas Manez, Kevin; Anthon, Alexander; Zhang, Zhe 2016-01-01 This paper presents a nonisolated Three Port Converter (TPC) with a unidirectional port for photovoltaic (PV) panels and a bidirectional port for energy storage. With the proposed topology single power conversion is performed between each port, so high efficiencies are obtained. A theoretical... 2. Atomic layer deposition for high-efficiency crystalline silicon solar cells NARCIS (Netherlands) Macco, B.; van de Loo, B.W.H.; Kessels, W.M.M.; Bachmann, J. 2017-01-01 This chapter illustrates that Atomic Layer Deposition (ALD) is in fact an enabler of novel high-efficiency Si solar cells, owing to its merits such as a high material quality, precise thickness control, and the ability to prepare film stacks in a well-controlled way. It gives an overview of the 3. ETV REPORT: EVALUATION OF HYDROMETRICS, INC., HIGH EFFICIENCY REVERSE OSMOSIS (HERO™) INDUSTRIAL WASTEWATER TREATMENT SYSTEM Science.gov (United States) Hydrometrics, founded in 1979 and located in Helena, MT, manufactures a commercial-ready High Efficiency Reverse Osmosis (HERO™) industrial wastewater treatment system. The system uses a three-stage reverse osmosis process to remove and concentrate metals for recovery while prod... 4. High efficiency thin-film solar cells for space applications: challenges and opportunities NARCIS (Netherlands) Leest, R.H. van 2017-01-01 In theory high efficiency thin-film III-V solar cells obtained by the epitaxial lift-off (ELO) technique offer excellent characteristics for application in space solar panels. The thesis describes several studies that investigate the space compatibility of the thin-film solar cell design developed 5. Ultra-high efficiency, fast graphene micro-heater on silicon DEFF Research Database (Denmark) Yan, Siqi; Zhu, Xiaolong; Frandsen, Lars Hagedorn 2017-01-01 We demonstrate an ultra-high efficiency and fast graphene microheater on silicon photonic crystal waveguide. By taking advantage of slow-light effect, a tuning efficiency of 1.07 nm/mW and power consumption per free spectral range of 3.99 mW. A fast rise and decay times (10% to 90%) of only 750 ns... 6. Compact high-efficiency vortex beam emitter based on a silicon photonics micro-ring DEFF Research Database (Denmark) Li, Shimao; Ding, Yunhong; Guan, Xiaowei 2018-01-01 Photonic integrated devices that emit vortex beam carrying orbital angular momentum are becoming key components for multiple applications. Here we propose and demonstrate a high-efficiency vortex beam emitter based on a silicon micro-ring resonator integrated with a metal mirror. Such a compact... 7. Standard specification for high efficiency particulate air filters. Revision No. 2 International Nuclear Information System (INIS) Porter, F.E. 1976-01-01 This specification covers the requirements for four types and four sizes of high efficiency particulate air filters, assembled with or without separators and gaskets. Types include Fire Resistant and Moisture Resistant; Hydrogen Fluoride Fume (HF) Resistant; Fire Resistant and Moisture Resistant and Chemical Resistant; and Fire Resistant and Moisture Resistant, High Temperature and High Humidity 8. SiC-based High Efficiency Bidirectional Battery Converter for Smart PV Residential Systems DEFF Research Database (Denmark) Pham, Cam; Biris, Valeriu-Ciprian; Teodorescu, Remus 2013-01-01 Smart PV inverters are essential components of future grids. Beside conventional functionalities they can communicate with the grid, supports the grid with reactive power and with active power from internal battery storage. To maximize internal consumption, a high efficiency bidirectional DC-DC c... 9. High-efficiency electric motors: An analysis of a feasible tariff policy for Brazil International Nuclear Information System (INIS) Paiva Delgado, M.A. de; Tolmasquim, M.T. 1997-01-01 The main objective is to calculate an average value for an electricity tariff which will facilitate the introduction of high-efficiency electric motors in the production sector. Two computational models will be developed for technical-economic evaluation to assess economic attractiveness by calculating feasible average electricity tariffs in order to create a market for substitution of standard motors by new high-efficiency models (Purchase Decision Model) as well as to determine if retrofitting of standard installed motors by others with high-efficiency characteristics is viable, and, if so, to specify the optimum timing for such substitution (Substitution Decision Model). It should be noted that the Purchase Decision Model takes into account power factor adjustment and the Substitution Decision Model incorporates considerations as to reduction in the electromechanical performance of operating motors. Results indicate that even where average electricity tariffs are low, as in Brazil, high-efficiency motors are economically attractive compared to standard motors. There is an obvious need for complementary instruments to assist massive market penetration 10. High efficiency three-phase power factor correction rectifier using SiC switches DEFF Research Database (Denmark) Kouchaki, Alireza; Nymand, Morten 2017-01-01 This paper presents designing procedure of a high efficiency 5 kW silicon-carbide (SiC) based threephase power factor correction (PFC). SiC switches present low capacitive switching loss compared to the alternative Si switches. Therefore, the switching frequency can be increased and hence the siz... 11. High efficiency battery converter with SiC devices for residential PV systems DEFF Research Database (Denmark) Pham, Cam; Teodorescu, Remus; Kerekes, Tamas 2013-01-01 The demand for high efficiency and higher power density is a challenge for Si-based semiconductors due to the physical characteristics of material. These can be overcome by employing wide-band-gap materials like SiC. This paper compares a second generator SiC MOSFETs against a normally-on Trench... 12. Highly efficient exciplex organic light-emitting diodes incorporating a heptazine derivative as an electron acceptor. Science.gov (United States) Li, Jie; Nomura, Hiroko; Miyazaki, Hiroshi; Adachi, Chihaya 2014-06-11 Highly efficient exciplex systems incorporating a heptazine derivative () as an electron acceptor and 1,3-di(9H-carbazol-9-yl)benzene () as an electron donor are developed. An organic light-emitting diode containing 8 wt% : as an emitting layer exhibits a maximum external quantum efficiency of 11.3%. 13. Silica nanoparticles as a highly efficient catalyst for the one-pot ... African Journals Online (AJOL) Silica nanoparticles as a highly efficient catalyst for the one-pot synthesis of sterically congested ... Bulletin of the Chemical Society of Ethiopia ... 42 nm) as a catalyst under solvent free conditions at room temperature is described. The ease of ... 14. Highly efficient tandem polymer solar cells with a photovoltaic response in the visible light range. Science.gov (United States) Zheng, Zhong; Zhang, Shaoqing; Zhang, Maojie; Zhao, Kang; Ye, Long; Chen, Yu; Yang, Bei; Hou, Jianhui 2015-02-18 Highly efficient polymer solar cells with a tandem structure are fabricated by using two excellent photovoltaic polymers and a highly transparent intermediate recombination layer. Power conversion -efficiencies over 10% can be realized with a photovoltaic response within 800 nm. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. 15. Metallic metasurfaces for high efficient polarization conversion control in transmission mode. Science.gov (United States) Li, Tong; Hu, Xiaobin; Chen, Huamin; Zhao, Chen; Xu, Yun; Wei, Xin; Song, Guofeng 2017-10-02 A high efficient broadband polarization converter is an important component in integrated miniaturized optical systems, but its performances is often restricted by the material structures, metallic metasurfaces for polarization control in transmission mode never achieved efficiency above 0.5. Herein, we theoretically demonstrate that metallic metasurfaces constructed by thick cross-shaped particles can realize a high efficient polarization transformation over a broadband. We investigated the resonant properties of designed matesurfaces and found that the interaction between double FP cavity resonances and double bulk magnetic resonances is the main reason to generate a high transmissivity over a broadband. In addition, through using four resonances effect and tuning the anisotropic optical response, we realized a high efficient (> 0.85) quarter-wave plate at the wavelength range from 1175nm to 1310nm and a high efficient (> 0.9) half-wave plate at the wavelength range from 1130nm to 1230nm. The proposed polarization converters may have many potential applications in integrated polarization conversion devices and optical data storage systems. 16. Modeling and experimental performance of an intermediate temperature reversible solid oxide cell for high-efficiency, distributed-scale electrical energy storage Science.gov (United States) Wendel, Christopher H.; Gao, Zhan; Barnett, Scott A.; Braun, Robert J. 2015-06-01 Electrical energy storage is expected to be a critical component of the future world energy system, performing load-leveling operations to enable increased penetration of renewable and distributed generation. Reversible solid oxide cells, operating sequentially between power-producing fuel cell mode and fuel-producing electrolysis mode, have the capability to provide highly efficient, scalable electricity storage. However, challenges ranging from cell performance and durability to system integration must be addressed before widespread adoption. One central challenge of the system design is establishing effective thermal management in the two distinct operating modes. This work leverages an operating strategy to use carbonaceous reactant species and operate at intermediate stack temperature (650 °C) to promote exothermic fuel-synthesis reactions that thermally self-sustain the electrolysis process. We present performance of a doped lanthanum-gallate (LSGM) electrolyte solid oxide cell that shows high efficiency in both operating modes at 650 °C. A physically based electrochemical model is calibrated to represent the cell performance and used to simulate roundtrip operation for conditions unique to these reversible systems. Design decisions related to system operation are evaluated using the cell model including current density, fuel and oxidant reactant compositions, and flow configuration. The analysis reveals tradeoffs between electrical efficiency, thermal management, energy density, and durability. 17. Development of High Efficiency Four-Terminal Perovskite-Silicon Tandems Science.gov (United States) Duong, The Duc This thesis is concerned with the development of high efficiency four-terminal perovskite-silicon tandem solar cells with the potential to reduce the cost of solar energy. The work focuses on perovskite top cells and can be divided into three main parts: developing low parasitic absorption and efficient semi-transparent perovskite cells, doping perovskite materials with rubidium, and optimizing perovskite material's bandgap with quadruple-cation and mixed-halide. A further section investigates the light stability of optimized bandgap perovskite cells. In a four-terminal mechanically stacked tandem, the perovskite top cell requires two transparent contacts at both the front and rear sides. Through detailed optical and electrical power loss analysis of the tandem efficiency due to non-ideal properties of the two transparent contacts, optimal contact parameters in term of sheet resistance and transparency are identified. Indium doped tin oxide by sputtering is used for both two transparent contacts and their deposition parameters are optimized separately. The semi-transparent perovskite cell using MAPbI3 has an efficiency of more than 12% with less than 12% parasitic absorption and up to 80% transparency in the long wavelength region. Using a textured foil as anti-reflection coating, an outstanding average transparency of 84% in the long wavelength is obtained. The low parasitic absorption allows an opaque version of the semi-transparent perovskite cell to operate efficiently in a filterless spectrum splitting perovskite-silicon tandem configuration. To further enhance the performance of perovskite cells, it is essential to improve the quality of perovskite films. This can be achieved with mixed-perovskite FAPbI3/MAPbBr3. However, mixed-perovskite films normally contain small a small amount of a non-perovskite phase, which is detrimental for the cell performance. Rb-doping is found to eliminate the formation of the non-perovskite phase and enhance the crystallinity of 18. Firetube boiler with high efficiency for producing saturated or superheated steam Energy Technology Data Exchange (ETDEWEB) Carosso, V J; Carosso, J Y 1976-10-07 This boiler for producing saturated or super-heated steam is to be manufactured in one piece or in units which can be assembled at site without skilled workers, at the factory. It is to have a high efficiency and dimensions which permit the transport of the completely assembled boiler by road transport. The relatively small water-steam vessel lies across the longitudinal axis of the boiler in the rear boiler space over a battery of preheater tubes. By these measures and by a very detailed and appropriately described rational arrangement of other parts, such as convection bundles, primary and secondary superheater, evaporation tubes, which form an 'evaporation shield', upper and lower longitudinal chambers with vertical connecting pipes of different crossections, the above mentioned condition for space requirement is fulfilled and a high efficiency should be achieved, but with considerable expense. 19. In silico evaluation of highly efficient organic light-emitting materials Science.gov (United States) Kwak, H. Shaun; Giesen, David J.; Hughes, Thomas F.; Goldberg, Alexander; Cao, Yixiang; Gavartin, Jacob; Dixon, Steve; Halls, Mathew D. 2016-09-01 Design and development of highly efficient organic and organometallic dopants is one of the central challenges in the organic light-emitting diodes (OLEDs) technology. Recent advances in the computational materials science have made it possible to apply computer-aided evaluation and screening framework directly to the design space of organic lightemitting diodes (OLEDs). In this work, we will showcase two major components of the latest in silico framework for development of organometallic phosphorescent dopants - (1) rapid screening of dopants by machine-learned quantum mechanical models and (2) phosphorescence lifetime predictions with spin-orbit coupled calculations (SOC-TDDFT). The combined work of virtual screening and evaluation would significantly widen the design space for highly efficient phosphorescent dopants with unbiased measures to evaluate performance of the materials from first principles. 20. A highly efficient electric additive for enhancing photovoltaic performance of dye-sensitized solar cells Institute of Scientific and Technical Information of China (English) 2010-01-01 N-cetylpyridinium iodide (N-CPI) as a new electric additive for enhancing photovoltaic performance of the dye-sensitized solar cell (DSSC) was studied.It showed high efficiency for enhancing both the open-circuit voltage and the short-circuit current density of DSSC when the suitable amount of N-CPI as 0.02 M was added in liquid electrolyte.The energy conversion effi- ciency of DSSC increased from 4.429% to 6.535%,with 47.55% enhancement.Therefore,it is a highly efficient electric addi- tive for DSSC.The intrinsic reason is owing to the special molecular structure of N-CPI,which contains two different polarity groups.As a surfactant,N-CPI could form ordered arrangement in liquid electrolyte,which affects the diffusing ability and the redox reaction of I-/I3-,and further affects the photovoltaic performance of DSSC. 1. Light-induced lattice expansion leads to high-efficiency perovskite solar cells Science.gov (United States) Tsai, Hsinhan; Asadpour, Reza; Blancon, Jean-Christophe; Stoumpos, Constantinos C.; Durand, Olivier; Strzalka, Joseph W.; Chen, Bo; Verduzco, Rafael; Ajayan, Pulickel M.; Tretiak, Sergei; Even, Jacky; Alam, Muhammad Ashraf; Kanatzidis, Mercouri G.; Nie, Wanyi; Mohite, Aditya D. 2018-04-01 Light-induced structural dynamics plays a vital role in the physical properties, device performance, and stability of hybrid perovskite–based optoelectronic devices. We report that continuous light illumination leads to a uniform lattice expansion in hybrid perovskite thin films, which is critical for obtaining high-efficiency photovoltaic devices. Correlated, in situ structural and device characterizations reveal that light-induced lattice expansion benefits the performances of a mixed-cation pure-halide planar device, boosting the power conversion efficiency from 18.5 to 20.5%. The lattice expansion leads to the relaxation of local lattice strain, which lowers the energetic barriers at the perovskite-contact interfaces, thus improving the open circuit voltage and fill factor. The light-induced lattice expansion did not compromise the stability of these high-efficiency photovoltaic devices under continuous operation at full-spectrum 1-sun (100 milliwatts per square centimeter) illumination for more than 1500 hours. 2. A Short Progress Report on High-Efficiency Perovskite Solar Cells. Science.gov (United States) Tang, He; He, Shengsheng; Peng, Chuangwei 2017-12-01 Faced with the increasingly serious energy and environmental crisis in the world nowadays, the development of renewable energy has attracted increasingly more attention of all countries. Solar energy as an abundant and cheap energy is one of the most promising renewable energy sources. While high-performance solar cells have been well developed in the last couple of decades, the high module cost largely hinders wide deployment of photovoltaic devices. In the last 10 years, this urgent demand for cost-effective solar cells greatly facilitates the research of solar cells. This paper reviews the recent development of cost-effective and high-efficient solar cell technologies. This report paper covers low-cost and high-efficiency perovskite solar cells. The development and the state-of-the-art results of perovskite solar cell technologies are also introduced. 3. Highly efficient Cu(In,Ga)Se2 solar cells grown on flexible polymer films. Science.gov (United States) Chirilă, Adrian; Buecheler, Stephan; Pianezzi, Fabian; Bloesch, Patrick; Gretener, Christina; Uhl, Alexander R; Fella, Carolin; Kranz, Lukas; Perrenoud, Julian; Seyrling, Sieghard; Verma, Rajneesh; Nishiwaki, Shiro; Romanyuk, Yaroslav E; Bilger, Gerhard; Tiwari, Ayodhya N 2011-09-18 Solar cells based on polycrystalline Cu(In,Ga)Se(2) absorber layers have yielded the highest conversion efficiency among all thin-film technologies, and the use of flexible polymer films as substrates offers several advantages in lowering manufacturing costs. However, given that conversion efficiency is crucial for cost-competitiveness, it is necessary to develop devices on flexible substrates that perform as well as those obtained on rigid substrates. Such comparable performance has not previously been achieved, primarily because polymer films require much lower substrate temperatures during absorber deposition, generally resulting in much lower efficiencies. Here we identify a strong composition gradient in the absorber layer as the main reason for inferior performance and show that, by adjusting it appropriately, very high efficiencies can be obtained. This implies that future manufacturing of highly efficient flexible solar cells could lower the cost of solar electricity and thus become a significant branch of the photovoltaic industry. 4. Highly Efficient Synthesis of 2-Aryl-3-methoxyacrylates via Suzuki-Miyaura Coupling Reaction Energy Technology Data Exchange (ETDEWEB) Kim, Hyung Ho; Lee, Chun Ho; Song, Young Seob; Park, No Kyun; Kim, Bum Tae; Heo, Jung Nyoung [Korea Research Institute of Chemical Technology, Daejeon (Korea, Republic of) 2006-02-15 We have developed a highly efficient and convergent synthesis of 2-aryl-3-methoxyacrylates via the Suzuki-Miyaura coupling reaction of α-iodo-β-methoxy-acrylate with arylboronic acids. The biological activities of 2-aryl-3-methoxyacrylate derivatives will be reported in due course. The Suzuki-Miyaura coupling reaction provides a convenient access to the carbon-carbon bond formation with high efficiency. Recently, a number of 2-aryl-3-methoxy-acrylates served as a key scaffold for the development of biologically active pharmaceuticals and agrochemicals. Especially, the discovery of the naturally-occurring fungicides, such as strobilurin A and oudemansin A, possessing a β-methoxyacrylate moiety was immediately seized great attention by industrial research groups to open a new era of the strobilurin family including azoxy-strobin and picoxystrobin. 5. A broadband high-efficiency Doherty power amplifier using symmetrical devices Science.gov (United States) Cheng, Zhiqun; Zhang, Ming; Li, Jiangzhou; Liu, Guohua 2018-04-01 This paper proposes a method for broadband and high-efficiency amplification of Doherty power amplifier (DPA) using symmetric devices. In order to achieve the perfect load modulation, the carrier amplifier output circuit total power length is designed to odd multiple of 90°, and the peak amplifier output total power length is designed to even multiple of 180°. The proposed method is demonstrated by designing a broadband high-efficiency DPA using identical 10-W packaged GaN HEMT devices. Measurement results show that over 51% drain efficiency is achieved at 6-dB back-off power, over the frequency band of 1.9–2.4 GHz. Project supported by the National Natural Science Foundation of China (No. 60123456), the Zhejiang Provincial Natural Science Foundation of China (No. LZ16F010001), and the Zhejiang Provincial Public Technology Research Project (No. 2016C31070). 6. Highly efficient single-layer dendrimer light-emitting diodes with balanced charge transport Science.gov (United States) Anthopoulos, Thomas D.; Markham, Jonathan P. J.; Namdas, Ebinazar B.; Samuel, Ifor D. W.; Lo, Shih-Chun; Burn, Paul L. 2003-06-01 High-efficiency single-layer-solution-processed green light-emitting diodes based on a phosphorescent dendrimer are demonstrated. A peak external quantum efficiency of 10.4% (35 cd/A) was measured for a first generation fac-tris(2-phenylpyridine) iridium cored dendrimer when blended with 4,4'-bis(N-carbazolyl)biphenyl and electron transporting 1,3,5-tris(2-N-phenylbenzimidazolyl)benzene at 8.1 V. A maximum power efficiency of 12.8 lm/W was measured also at 8.1 V and 550 cd/m2. These results indicate that, by simple blending of bipolar and electron-transporting molecules, highly efficient light-emitting diodes can be made employing a very simple device structure. 7. State Support for Promotion of Electrical Energy Produced in High Efficiency Cogeneration in Romania Directory of Open Access Journals (Sweden) Mushatescu V. 2016-12-01 Full Text Available Romania accumulated a useful experience in supporting high efficient cogeneration through a bonus type scheme. Spreading this experience to other countries that can choose a similar support scheme could lead to important savings and better results in developing this efficient tool. This state aid is operational, targeted to new investments stimulation for cogeneration technologies and replacement or existing plants rehabilitation. Present paper focuses on the results of support scheme after five years of its application: increase of number of producers who benefit of this aid, raising of general efficiency of high efficient cogeneration, important savings of primary energy and CO2 emissions avoided. On the other hand, use of this scheme showed a number of problems (to which this paper proposes adequate solutions on institutional/administrative, investition, technical, economical-financial and social frameworks that influences beneficiaries and/or financiers of state aid. 8. Compact and high-efficiency device for Raman scattering measurement using optical fibers. Science.gov (United States) Mitsui, Tadashi 2014-11-01 We describe the design and development of a high-efficiency optical measurement device for operation within the small bore of a high-power magnet at low temperature. For the high-efficiency measurement of light emitted from this small region, we designed a compact confocal optics with lens focusing and tilting systems, and used a piezodriven translation stage that allows micron-scale focus control of the sample position. We designed a measurement device that uses 10 m-long optical fibers in order to avoid the influence of mechanical vibration and magnetic field leakage of high-power magnets, and we also describe a technique for minimizing the fluorescence signal of optical fibers. The operation of the device was confirmed by Raman scattering measurements of monolayer graphene on quartz glass with a high signal-to-noise ratio. 9. Seawater splitting for high-efficiency hydrogen evolution by alloyed PtNix electrocatalysts Science.gov (United States) Zheng, Jingjing 2017-08-01 Robust electrocatalyst is a prerequisite to realize high-efficiency hydrogen evolution by water splitting. Expensive platinum (Pt) is a preferred electrode catalyst for state-of-the-art hydrogen evolution reaction (HER). We present here a category of alloyed PtNix electrocatalysts by a facile green chemical reduction method, which are used to catalyze HER during seawater splitting. The catalytic performances are optimized by tuning stoichiometric Pt/Ni ratio, yielding a maximized catalytic behavior for PtNi5 electrode. The minimized onset potential is as low as -0.38 V and the corresponding Tafel slope is 119 mV dec-1. Moreover, the launched alloy electrodes have remarkable stability at -1.2 V over 12 h. The high efficiency as well as good durability demonstrates the PtNix electrocatalysts to be promising in practical applications. 10. Highly efficient red OLEDs using DCJTB as the dopant and delayed fluorescent exciplex as the host. Science.gov (United States) Zhao, Bo; Zhang, Tianyou; Chu, Bei; Li, Wenlian; Su, Zisheng; Wu, Hairuo; Yan, Xingwu; Jin, Fangming; Gao, Yuan; Liu, Chengyuan 2015-05-29 In this manuscript, we demonstrated a highly efficient DCJTB emission with delayed fluorescent exciplex TCTA:3P-T2T as the host. For the 1.0% DCJTB doped concentration, a maximum luminance, current efficiency, power efficiency and EQE of 22,767 cd m(-2), 22.7 cd A(-1), 21.5 lm W(-1) and 10.15% were achieved, respectively. The device performance is the best compared to either red OLEDs with traditional fluorescent emitter or traditional red phosphor of Ir(piq)3 doped into CBP host. The extraction of so high efficiency can be explained as the efficient triplet excitons up-conversion of TCTA:3P-T2T and the energy transfer from exciplex host singlet state to DCJTB singlet state. 11. Highly efficient deep-blue organic light emitting diode with a carbazole based fluorescent emitter Science.gov (United States) Sahoo, Snehasis; Dubey, Deepak Kumar; Singh, Meenu; Joseph, Vellaichamy; Thomas, K. R. Justin; Jou, Jwo-Huei 2018-04-01 High efficiency deep-blue emission is essential to realize energy-saving, high-quality display and lighting applications. We demonstrate here a deep-blue organic light emitting diode using a novel carbazole based fluorescent emitter 7-[4-(diphenylamino)phenyl]-9-(2-ethylhexyl)-9H-carbazole-2-carbonitrile (JV234). The solution processed resultant device shows a maximum luminance above 1,750 cd m-2 and CIE coordinates (0.15,0.06) with a 1.3 lm W-1 power efficiency, 2.0 cd A-1 current efficiency, and 4.1% external quantum efficiency at 100 cd m-2. The resulting deep-blue emission enables a greater than 100% color saturation. The high efficiency may be attributed to the effective host-to-guest energy transfer, suitable device architecture facilitating balanced carrier injection and low doping concentration preventing efficiency roll-off caused by concentration quenching. 12. High-efficiency one-dimensional atom localization via two parallel standing-wave fields International Nuclear Information System (INIS) Wang, Zhiping; Wu, Xuqiang; Lu, Liang; Yu, Benli 2014-01-01 We present a new scheme of high-efficiency one-dimensional (1D) atom localization via measurement of upper state population or the probe absorption in a four-level N-type atomic system. By applying two classical standing-wave fields, the localization peak position and number, as well as the conditional position probability, can be easily controlled by the system parameters, and the sub-half-wavelength atom localization is also observed. More importantly, there is 100% detecting probability of the atom in the subwavelength domain when the corresponding conditions are satisfied. The proposed scheme may open up a promising way to achieve high-precision and high-efficiency 1D atom localization. (paper) 13. Broadband and high efficiency all-dielectric metasurfaces for wavefront steering with easily obtained phase shift Science.gov (United States) Yang, Hui; Deng, Yan 2017-12-01 All-dielectric metasurfaces for wavefront deflecting and optical vortex generating with broadband and high efficiency are demonstrated. The unit cell of the metasurfaces is optimized to function as a half wave-plate with high polarization conversion efficiency (94%) and transmittance (94.5%) at the telecommunication wavelength. Under such a condition, we can get rid of the complicated parameter sweep process for phase shift selecting. Hence, a phase coverage ranges from 0 to 2 π can be easily obtained by introducing the Pancharatnam-Berry phase. Metasurfaces composed of the two pre-designed super cells are demonstrated for optical beam deflecting and vortex beam generating. It is found that the metasurfaces with more phase shift sampling points (small phase shift increment) exhibit better performance. Moreover, optical vortex beams can be generated by the designed metasurfaces within a wavelength range of 200 nm. These results will provide a viable route for designing broadband and high efficiency devices related to phase modulation. 14. High efficiency diffractive grating coupler based on transferred silicon nanomembrane overlay on photonic waveguide Energy Technology Data Exchange (ETDEWEB) Saha, Tapas Kumar; Zhou Weidong [University of Texas at Arlington, Department of Electrical Engineering, NanoFAB Center, Arlington, TX 76019-0072 (United States) 2009-04-21 We report here the design of a new type of high efficiency grating coupler, based on single crystalline Si nanomembrane overlay and stacking. Such high efficiency diffractive grating couplers are designed for the purpose of coupling light between single mode fibres and nanophotonic waveguides, and for the coupling between multiple photonic interconnect layers for compact three-dimensional vertical integration. Two-dimensional model simulation based on eigenmode expansion shows a diffractive power-up efficiency of 81% and a fibre coupling efficiency of 64%. With nanomembrane stacking, it is feasible to integrate the side-distributed Bragg reflector and bottom reflector, which can lead to the diffractive power-up efficiency and the fibre coupling efficiency of 97% and 73.5%, respectively. For a negatively detuned coupler, the bottom reflector is not needed, and the diffractive power-up efficiency can reach 98% over a large spectral range. The device is extremely tolerant to fabrication errors. 15. Holography as a highly efficient renormalization group flow. I. Rephrasing gravity Science.gov (United States) Behr, Nicolas; Kuperstein, Stanislav; Mukhopadhyay, Ayan 2016-07-01 We investigate how the holographic correspondence can be reformulated as a generalization of Wilsonian renormalization group (RG) flow in a strongly interacting large-N quantum field theory. We first define a highly efficient RG flow as one in which the Ward identities related to local conservation of energy, momentum and charges preserve the same form at each scale. To achieve this, it is necessary to redefine the background metric and external sources at each scale as functionals of the effective single-trace operators. These redefinitions also absorb the contributions of the multitrace operators to these effective Ward identities. Thus, the background metric and external sources become effectively dynamical, reproducing the dual classical gravity equations in one higher dimension. Here, we focus on reconstructing the pure gravity sector as a highly efficient RG flow of the energy-momentum tensor operator, leaving the explicit constructive field theory approach for generating such RG flows to the second part of the work. We show that special symmetries of the highly efficient RG flows carry information through which we can decode the gauge fixing of bulk diffeomorphisms in the corresponding gravity equations. We also show that the highly efficient RG flow which reproduces a given classical gravity theory in a given gauge is unique provided the endpoint can be transformed to a nonrelativistic fixed point with a finite number of parameters under a universal rescaling. The results obtained here are used in the second part of this work, where we do an explicit field-theoretic construction of the RG flow and obtain the dual classical gravity theory. 16. Highly-Efficient Thermoelectronic Conversion of Heat and Solar Radiation to Electric Power OpenAIRE Meir, Stefan 2013-01-01 Thermionic energy conversion has long been a candidate to convert solar radiation and the combustion heat of fossil fuels into electricity at high efficiencies. However, the formation of electron space charges has prevented the widespread use of the principle since its was first suggested in 1915. In this work, a novel mechanism to suppress the effects of the space charge was investigated: the acceleration of electrons in a special configuration of electric and magnetic fields. This work d... 17. Analysis of Valve Requirements for High-Efficiency Digital Displacement Fluid Power Motors DEFF Research Database (Denmark) Rømer, Daniel; Johansen, Per; Pedersen, Henrik C. 2013-01-01 Digital displacement fluid power motors have been shown to enable high-efficiency operation in a wide operation range, including the part load range where conventional fluid power motors suffers from poor efficiencies. The use of these digital displacement motors set new requirements for the valve...... transition time and flow-pressure coefficient are normalized, leading to a presentation of the general efficiency map of the digital displacement motor. Finally the performance of existing commercial valves with respect to digital motors is commented.... 18. Simple Retrofit High-Efficiency Natural Gas Water Heater Field Test Energy Technology Data Exchange (ETDEWEB) Schoenbauer, Ben [NorthernSTAR, St. Paul, MN (United States) 2017-03-01 High-performance water heaters are typically more time consuming and costly to install in retrofit applications, making high performance water heaters difficult to justify economically. However, recent advancements in high performance water heaters have targeted the retrofit market, simplifying installations and reducing costs. Four high efficiency natural gas water heaters designed specifically for retrofit applications were installed in single-family homes along with detailed monitoring systems to characterize their savings potential, their installed efficiencies, and their ability to meet household demands. The water heaters tested for this project were designed to improve the cost-effectiveness and increase market penetration of high efficiency water heaters in the residential retrofit market. The retrofit high efficiency water heaters achieved their goal of reducing costs, maintaining savings potential and installed efficiency of other high efficiency water heaters, and meeting the necessary capacity in order to improve cost-effectiveness. However, the improvements were not sufficient to achieve simple paybacks of less than ten years for the incremental cost compared to a minimum efficiency heater. Significant changes would be necessary to reduce the simple payback to six years or less. Annual energy savings in the range of$200 would also reduce paybacks to less than six years. These energy savings would require either significantly higher fuel costs (greater than $1.50 per therm) or very high usage (around 120 gallons per day). For current incremental costs, the water heater efficiency would need to be similar to that of a heat pump water heater to deliver a six year payback. 19. High-efficiency diode-pumped femtosecond Yb:YAG ceramic laser DEFF Research Database (Denmark) Zhou, Binbin; Wei, Z.Y.; Zou, Y.W. 2010-01-01 A highly efficient diode-end-pumped femtosecond Yb:yttrium aluminum garnet (YAG) ceramic laser was demonstrated. Pumped by a 968 nm fiber-coupled diode laser, 1.9 W mode-locked output power at a repetition rate of 64.27 MHz was obtained with 3.5 W absorbed pump power, corresponding to a slope...... efficiency of 76%. Our measurement showed that the pulse duration was 418 fs with the central wavelength of 1048 nm.... 20. Synergistic effect of fluorination on molecular energy level modulation in highly efficient photovoltaic polymers. Science.gov (United States) Zhang, Maojie; Guo, Xia; Zhang, Shaoqing; Hou, Jianhui 2014-02-01 The synergistic effect of fluorination on molecular energy level modulation is realized by introducing fluorine atoms onto both the donor and the acceptor moieties in a D-A polymer, and as a result, the polymer solar cell device based on the trifluorinated polymer, PBT-3F, shows a high efficiency of 8.6%, under illumination of AM 1.5G, 100 mW cm(-) (2) . © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. 1. The Mechanism of Burn-in Loss in a High Efficiency Polymer Solar Cell KAUST Repository Peters, Craig H. 2011-10-11 Degradation in a high efficiency polymer solar cell is caused by the formation of states in the bandgap. These states increase the energetic disorder in the system. The power conversion efficiency loss does not occur when current is run through the device in the dark but occurs when the active layer is photo-excited. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. 2. High Efficiency Non-isolated Three Port DC-DC Converter for PV-Battery Systems OpenAIRE Tomas Manez, Kevin; Anthon, Alexander; Zhang, Zhe; Ouyang, Ziwei; Franke, Toke 2016-01-01 This paper presents a nonisolated Three Port Converter (TPC) with a unidirectional port for photovoltaic (PV) panels and a bidirectional port for energy storage. With the proposed topology single power conversion is performed between each port, so high efficiencies are obtained. A theoretical analysis is carried out to analyze all operating modes and design considerations with the main equations are given. A 4kW laboratory prototype is developed and tested under all operatingconditions. Resul... 3. High Efficiency Large-Angle Pancharatnam Phase Deflector Based on Dual Twist Design Science.gov (United States) 2016-12-16 construction and characterization of a ±40° beam steering device with 90% diffraction efficiency based on our dual-twist design at 633nm wavelength...N. & Escuti, M. J. Achromatic Wollaston prism beam splitter using polarization gratings. Opt. Lett. 41, 4461–4463 (2016). 13. Slussarenko, S., et...High-efficiency large-angle Pancharatnam phase deflector based on dual-twist design Kun Gao1, Colin McGinty1, Harold Payson2, Shaun Berry2, Joseph 4. Highly-efficient, flexible piezoelectric PZT thin film nanogenerator on plastic substrates. Science.gov (United States) Park, Kwi-Il; Son, Jung Hwan; Hwang, Geon-Tae; Jeong, Chang Kyu; Ryu, Jungho; Koo, Min; Choi, Insung; Lee, Seung Hyun; Byun, Myunghwan; Wang, Zhong Lin; Lee, Keon Jae 2014-04-23 A highly-efficient, flexible piezoelectric PZT thin film nanogenerator is demonstrated using a laser lift-off (LLO) process. The PZT thin film nanogenerator harvests the highest output performance of ∼200 V and ∼150 μA·cm(-2) from regular bending motions. Furthermore, power sources generated from a PZT thin film nanogenerator, driven by slight human finger bending motions, successfully operate over 100 LEDs. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. 5. Mild and Highly Efficient Copper(I Inspired Acylation of Alcohols and Polyols Directory of Open Access Journals (Sweden) Enoch A. Mensah 2017-01-01 Full Text Available A new and highly efficient method mediated by tetrakis(acetonitrilecopper(I triflate for activating both simple and highly hindered anhydrides in the acylation of alcohols and polyols is described. This new acylation method is mild and mostly proceeds at room temperature with low catalyst loading. The method is versatile and has been extended to a wide variety of different alcohol substrates to afford the corresponding ester products in good to excellent yields. 6. Results from the high efficiency solar panel experiment flown on CRRES International Nuclear Information System (INIS) Ray, K.P.; Mullen, E.G.; Trumble, T.M. 1993-01-01 This paper presents results from the High Efficiency Solar Panel Experiment (HESP) flown on the Combined Release and Radiation Effects Satellite (CRRES). The on-orbit solar cell degradation is correlated with the proton and electron environments. Comparisons between gallium arsenide germanium (GaAs/Ge) and silicon (Si) solar cells are presented, and results from three different annealing methods of like GaAs solar cells are compared 7. High Efficiency Power Converter for a Doubly-fed SOEC/SOFC System DEFF Research Database (Denmark) Tomas Manez, Kevin; Anthon, Alexander; Zhang, Zhe 2016-01-01 Regenerative fuel cells (RFC) have become an attractive technology for energy storage systems due to their high energy density and lower end-of-life disposal concerns. However, high efficiency design of power conditioning unit (PCU) for RFC becomes challenging due to their asymmetrical currentpow...... operating range of the RFC as well as the utilization of the same control strategy design for the two RFC operating modes.... 8. Simple Retrofit High-Efficiency Natural Gas Water Heater Field Test Energy Technology Data Exchange (ETDEWEB) Schoenbauer, Ben [NorthernSTAR, St. Paul, MN (United States) 2017-03-28 High performance water heaters are typically more time consuming and costly to install in retrofit applications, making high performance water heaters difficult to justify economically. However, recent advancements in high performance water heaters have targeted the retrofit market, simplifying installations and reducing costs. Four high efficiency natural gas water heaters designed specifically for retrofit applications were installed in single-family homes along with detailed monitoring systems to characterize their savings potential, their installed efficiencies, and their ability to meet household demands. The water heaters tested for this project were designed to improve the cost-effectiveness and increase market penetration of high efficiency water heaters in the residential retrofit market. The retrofit high efficiency water heaters achieved their goal of reducing costs, maintaining savings potential and installed efficiency of other high efficiency water heaters, and meeting the necessary capacity in order to improve cost-effectiveness. However, the improvements were not sufficient to achieve simple paybacks of less than ten years for the incremental cost compared to a minimum efficiency heater. Significant changes would be necessary to reduce the simple payback to six years or less. Annual energy savings in the range of$200 would also reduce paybacks to less than six years. These energy savings would require either significantly higher fuel costs (greater than 1.50 per therm) or very high usage (around 120 gallons per day). For current incremental costs, the water heater efficiency would need to be similar to that of a heat pump water heater to deliver a six year payback. 9. Research & Implementation of AC - DC Converter with High Power Factor & High Efficiency Directory of Open Access Journals (Sweden) Hsiou-Hsian Nien 2014-05-01 Full Text Available In this paper, we design and develop a high power factor, high efficiency two-stage AC - DC power converter. This paper proposes a two-stage AC - DC power converter. The first stage is boost active power factor correction circuit. The latter stage is near constant frequency LLC resonant converter. In addition to traditional LLC high efficiency advantages, light-load conversion efficiency of this power converter can be improved. And it possesses high power factor and near constant frequency operating characteristics, can significantly reduce the electromagnetic interference. This paper first discusses the main structure and control manner of power factor correction circuit. And then by the LLC resonant converter equivalent model proceed to circuit analysis to determine the important parameters of the converter circuit elements. Then design a variable frequency resonant tank. The resonant frequency can change automatically on the basis of the load to reach near constant frequency operation and a purpose of high efficiency. Finally, actually design and produce an AC – DC power converter with output of 190W to verify the characteristics and feasibility of this converter. The experimental results show that in a very light load (9.5 W the efficiency is as high as 81%, the highest efficiency of 88% (90 W. Full load efficiency is 87%. At 19 W ~ 190 W power changes, the operating frequency change is only 0.4 kHz (AC 110 V and 0.3 kHz (AC 220 V. 10. The Design of High Efficiency Crossflow Hydro Turbines: A Review and Extension Directory of Open Access Journals (Sweden) Ram Adhikari 2018-01-01 Full Text Available Efficiency is a critical consideration in the design of hydro turbines. The crossflow turbine is the cheapest and easiest hydro turbine to manufacture and so is commonly used in remote power systems for developing countries. A longstanding problem for practical crossflow turbines is their lower maximum efficiency compared to their more advanced counterparts, such as Pelton and Francis turbines. This paper reviews the experimental and computational studies relevant to the design of high efficiency crossflow turbines. We concentrate on the studies that have contributed to designs with efficiencies in the range of 88–90%. Many recent studies have been conducted on turbines of low maximum efficiency, which we believe is due to misunderstanding of design principles for achieving high efficiencies. We synthesize the key results of experimental and computational fluid dynamics studies to highlight the key fundamental design principles for achieving efficiencies of about 90%, as well as future research and development areas to further improve the maximum efficiency. The main finding of this review is that the total conversion of head into kinetic energy in the nozzle and the matching of nozzle and runner designs are the two main design requirements for the design of high efficiency turbines. 11. High Current Planar Transformer for Very High Efficiency Isolated Boost DC-DC Converters DEFF Research Database (Denmark) Pittini, Riccardo; Zhang, Zhe; Andersen, Michael A. E. 2014-01-01 This paper presents a design and optimization of a high current planar transformer for very high efficiency dc-dc isolated boost converters. The analysis considers different winding arrangements, including very high copper thickness windings. The analysis is focused on the winding ac-resistance a......This paper presents a design and optimization of a high current planar transformer for very high efficiency dc-dc isolated boost converters. The analysis considers different winding arrangements, including very high copper thickness windings. The analysis is focused on the winding ac......-resistance and transformer leakage inductance. Design and optimization procedures are validated based on an experimental prototype of a 6 kW dcdc isolated full bridge boost converter developed on fully planar magnetics. The prototype is rated at 30-80 V 0-80 A on the low voltage side and 700-800 V on the high voltage side...... with a peak efficiency of 97.8% at 80 V 3.5 kW. Results highlights that thick copper windings can provide good performance at low switching frequencies due to the high transformer filling factor. PCB windings can also provide very high efficiency if stacked in parallel utilizing the transformer winding window... 12. Highly efficient white top-emitting organic light-emitting diodes with forward directed light emission Energy Technology Data Exchange (ETDEWEB) Freitag, Patricia; Reineke, Sebastian; Furno, Mauro; Luessem, Bjoern; Leo, Karl [Institut fuer Angewandte Photophysik, TU Dresden (Germany) 2010-07-01 The demand for highly efficient and energy saving illumination has increased considerably during the last decades. Organic light emitting diodes (OLEDs) are promising candidates for future lighting technologies. They offer high efficiency along with excellent color quality, allowing substantially lower power consumption than traditional illuminants. Recently, especially top-emitting devices have attracted high interest due to their compatibility with opaque substrates like metal sheets. In this contribution, we demonstrate top-emitting OLEDs with white emission spectra employing a multilayer hybrid cavity structure with two highly efficient phosphorescent emitter materials for orange-red (Ir(MDQ)2(acac)) and green (Ir(ppy)3) emission as well as the stable fluorescent blue emitter TBPe. To improve the OLED performance and modify the color quality, two different electron blocking layers and anode material combinations are tested. Compared to Lambertian emission, our devices show considerably enhanced forward emission, which is preferred for most lighting applications. Besides broadband emission and angle independent emission maxima, power efficiencies of 13.3 lm/W at 3 V and external quantum efficiencies of 5.3% are achieved. The emission shows excellent CIE coordinates of (0.420,0.407) at approx. 1000 cd/m{sup 2} and color rendering indices up to 77. 13. Highly efficient CRISPR/HDR-mediated knock-in for mouse embryonic stem cells and zygotes. Science.gov (United States) Wang, Bangmei; Li, Kunyu; Wang, Amy; Reiser, Michelle; Saunders, Thom; Lockey, Richard F; Wang, Jia-Wang 2015-10-01 The clustered regularly interspaced short palindromic repeat (CRISPR) gene editing technique, based on the non-homologous end-joining (NHEJ) repair pathway, has been used to generate gene knock-outs with variable sizes of small insertion/deletions with high efficiency. More precise genome editing, either the insertion or deletion of a desired fragment, can be done by combining the homology-directed-repair (HDR) pathway with CRISPR cleavage. However, HDR-mediated gene knock-in experiments are typically inefficient, and there have been no reports of successful gene knock-in with DNA fragments larger than 4 kb. Here, we describe the targeted insertion of large DNA fragments (7.4 and 5.8 kb) into the genomes of mouse embryonic stem (ES) cells and zygotes, respectively, using the CRISPR/HDR technique without NHEJ inhibitors. Our data show that CRISPR/HDR without NHEJ inhibitors can result in highly efficient gene knock-in, equivalent to CRISPR/HDR with NHEJ inhibitors. Although NHEJ is the dominant repair pathway associated with CRISPR-mediated double-strand breaks (DSBs), and biallelic gene knock-ins are common, NHEJ and biallelic gene knock-ins were not detected. Our results demonstrate that efficient targeted insertion of large DNA fragments without NHEJ inhibitors is possible, a result that should stimulate interest in understanding the mechanisms of high efficiency CRISPR targeting in general. 14. Cu2O/CuO Bilayered Composite as a High-Efficiency Photocathode for Photoelectrochemical Hydrogen Evolution Reaction Science.gov (United States) Yang, Yang; Xu, Di; Wu, Qingyong; Diao, Peng 2016-10-01 Solar powered hydrogen evolution reaction (HER) is one of the key reactions in solar-to-chemical energy conversion. It is desirable to develop photocathodic materials that exhibit high activity toward photoelectrochemical (PEC) HER at more positive potentials because a higher potential means a lower overpotential for HER. In this work, the Cu2O/CuO bilayered composites were prepared by a facile method that involved an electrodeposition and a subsequent thermal oxidation. The resulting Cu2O/CuO bilayered composites exhibited a surprisingly high activity and good stability toward PEC HER, expecially at high potentials in alkaline solution. The photocurrent density for HER was 3.15 mA·cm-2 at the potential of 0.40 V vs. RHE, which was one of the two highest reported at the same potential on copper-oxide-based photocathode. The high photoactivity of the bilayered composite was ascribed to the following three advantages of the Cu2O/CuO heterojunction: (1) the broadened light absorption band that made more efficient use of solar energy, (2) the large space-charge-region potential that enabled a high efficiency for electron-hole separation, and (3) the high majority carrier density that ensured a faster charge transportation rate. This work reveals the potential of the Cu2O/CuO bilayered composite as a promising photocathodic material for solar water splitting. 15. Highly efficient nonprecious metal catalyst prepared with metal–organic framework in a continuous carbon nanofibrous network Science.gov (United States) Shui, Jianglan; Chen, Chen; Grabstanowicz, Lauren; Zhao, Dan; Liu, Di-Jia 2015-01-01 Fuel cell vehicles, the only all-electric technology with a demonstrated >300 miles per fill travel range, use Pt as the electrode catalyst. The high price of Pt creates a major cost barrier for large-scale implementation of polymer electrolyte membrane fuel cells. Nonprecious metal catalysts (NPMCs) represent attractive low-cost alternatives. However, a significantly lower turnover frequency at the individual catalytic site renders the traditional carbon-supported NPMCs inadequate in reaching the desired performance afforded by Pt. Unconventional catalyst design aiming at maximizing the active site density at much improved mass and charge transports is essential for the next-generation NPMC. We report here a method of preparing highly efficient, nanofibrous NPMC for cathodic oxygen reduction reaction by electrospinning a polymer solution containing ferrous organometallics and zeolitic imidazolate framework followed by thermal activation. The catalyst offers a carbon nanonetwork architecture made of microporous nanofibers decorated by uniformly distributed high-density active sites. In a single-cell test, the membrane electrode containing such a catalyst delivered unprecedented volumetric activities of 3.3 A⋅cm−3 at 0.9 V or 450 A⋅cm−3 extrapolated at 0.8 V, representing the highest reported value in the literature. Improved fuel cell durability was also observed. PMID:26261338 16. Giant energy density and high efficiency achieved in bismuth ferrite-based film capacitors via domain engineering. Science.gov (United States) Pan, Hao; Ma, Jing; Ma, Ji; Zhang, Qinghua; Liu, Xiaozhi; Guan, Bo; Gu, Lin; Zhang, Xin; Zhang, Yu-Jun; Li, Liangliang; Shen, Yang; Lin, Yuan-Hua; Nan, Ce-Wen 2018-05-08 Developing high-performance film dielectrics for capacitive energy storage has been a great challenge for modern electrical devices. Despite good results obtained in lead titanate-based dielectrics, lead-free alternatives are strongly desirable due to environmental concerns. Here we demonstrate that giant energy densities of ~70 J cm -3 , together with high efficiency as well as excellent cycling and thermal stability, can be achieved in lead-free bismuth ferrite-strontium titanate solid-solution films through domain engineering. It is revealed that the incorporation of strontium titanate transforms the ferroelectric micro-domains of bismuth ferrite into highly-dynamic polar nano-regions, resulting in a ferroelectric to relaxor-ferroelectric transition with concurrently improved energy density and efficiency. Additionally, the introduction of strontium titanate greatly improves the electrical insulation and breakdown strength of the films by suppressing the formation of oxygen vacancies. This work opens up a feasible and propagable route, i.e., domain engineering, to systematically develop new lead-free dielectrics for energy storage. 17. Tunneling effects in the current-voltage characteristics of high-efficiency GaAs solar cells Science.gov (United States) Kachare, R.; Anspaugh, B. E.; Garlick, G. F. J. 1988-01-01 Evidence is that tunneling via states in the forbidden gap is the dominant source of excess current in the dark current-voltage (I-V) characteristics of high-efficiency DMCVD grown Al(x)Ga(1-x)As/GaAs(x is equal to or greater than 0.85) solar cells. The dark forward and reverse I-V measurements were made on several solar cells, for the first time, at temperatures between 193 and 301 K. Low-voltage reverse-bias I-V data of a number of cells give a thermal activation energy for excess current of 0.026 + or - 0.005 eV, which corresponds to the carbon impurity in GaAs. However, other energy levels between 0.02 eV and 0.04 eV were observed in some cells which may correspond to impurity levels introduced by Cu, Si, Ge, or Cd. The forward-bias excess current is mainly due to carrier tunneling between localized levels created in the space-charge layer by impurities such as carbon, which are incorporated during the solar cell growth process. A model is suggested to explain the results. 18. Highly Efficient and Stable Organic Solar Cells via Interface Engineering with a Nanostructured ITR-GO/PFN Bilayer Cathode Interlayer Directory of Open Access Journals (Sweden) Ding Zheng 2017-08-01 Full Text Available An innovative bilayer cathode interlayer (CIL with a nanostructure consisting of in situ thermal reduced graphene oxide (ITR-GO and poly[(9,9-bis(3′-(N,N-dimethylamionpropyl-2,7-fluorene-alt-2,7-(9,9-dioctyl fluorene] (PFN has been fabricated for inverted organic solar cells (OSCs. An approach to prepare a CIL of high electronic quality by using ITR-GO as a template to modulate the morphology of the interface between the active layer and electrode and to further reduce the work function of the electrode has also been realized. This bilayer ITR-GO/PFN CIL is processed by a spray-coating method with facile in situ thermal reduction. Meanwhile, the CIL shows a good charge transport efficiency and less charge recombination, which leads to a significant enhancement of the power conversion efficiency from 6.47% to 8.34% for Poly({4,8-bis[(2-ethylhexyloxy]benzo[1,2-b:4,5-b′]dithiophene-2,6-diyl}{3-fluoro-2-[(2-ethylhexylcarbonyl]thieno[3,4-b]thiophenediyl} (PTB7:[6,6]-phenyl-C71-butyric acid methyl ester (PC71BM-based OSCs. In addition, the long-term stability of the OSC is improved by using the ITR-GO/PFN CIL when compared with the pristine device. These results indicate that the bilayer ITR-GO/PFN CIL is a promising way to realize high-efficiency and stable OSCs by using water-soluble conjugated polymer electrolytes such as PFN. 19. Self-cleaning threaded rod spinneret for high-efficiency needleless electrospinning Science.gov (United States) Zheng, Gaofeng; Jiang, Jiaxin; Wang, Xiang; Li, Wenwang; Zhong, Weizheng; Guo, Shumin 2018-07-01 High-efficiency production of nanofibers is the key to the application of electrospinning technology. This work focuses on multi-jet electrospinning, in which a threaded rod electrode is utilized as the needless spinneret to achieve high-efficiency production of nanofibers. A slipper block, which fits into and moves through the threaded rod, is designed to transfer polymer solution evenly to the surface of the rod spinneret. The relative motion between the slipper block and the threaded rod electrode promotes the instable fluctuation of the solution surface, thus the rotation of threaded rod electrode decreases the critical voltage for the initial multi-jet ejection and the diameter of nanofibers. The residual solution on the surface of threaded rod is cleaned up by the moving slipper block, showing a great self-cleaning ability, which ensures the stable multi-jet ejection and increases the productivity of nanofibers. Each thread of the threaded rod electrode serves as an independent spinneret, which enhances the electric field strength and constrains the position of the Taylor cone, resulting in high productivity of uniform nanofibers. The diameter of nanofibers decreases with the increase of threaded rod rotation speed, and the productivity increases with the solution flow rate. The rotation of electrode provides an excess force for the ejection of charged jets, which also contributes to the high-efficiency production of nanofibers. The maximum productivity of nanofibers from the threaded rod spinneret is 5-6 g/h, about 250-300 times as high as that from the single-needle spinneret. The self-cleaning threaded rod spinneret is an effective way to realize continuous multi-jet electrospinning, which promotes industrial applications of uniform nanofibrous membrane. 20. Fractal-Like Materials Design with Optimized Radiative Properties for High-Efficiency Solar Energy Conversion Energy Technology Data Exchange (ETDEWEB) Ho, Clifford K. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Concentrating Solar Technologies Dept.; Ortega, Jesus D. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Concentrating Solar Technologies Dept.; Christian, Joshua Mark [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Concentrating Solar Technologies Dept.; Yellowhair, Julius E. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Concentrating Solar Technologies Dept.; Ray, Daniel A. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Concentrating Solar Technologies Dept.; Kelton, John W. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Concentrating Solar Technologies Dept.; Peacock, Gregory [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Concentrating Solar Technologies Dept.; Andraka, Charles E. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Concentrating Solar Technologies Dept.; Shinde, Subhash [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Concentrating Solar Technologies Dept. 2016-09-01 Novel designs to increase light trapping and thermal efficiency of concentrating solar receivers at multiple length scales have been conceived, designed, and tested. The fractal-like geometries and features are introduced at both macro (meters) and meso (millimeters to centimeters) scales. Advantages include increased solar absorptance, reduced thermal emittance, and increased thermal efficiency. Radial and linear structures at the meso (tube shape and geometry) and macro (total receiver geometry and configuration) scales redirect reflected solar radiation toward the interior of the receiver for increased absorptance. Hotter regions within the interior of the receiver can reduce thermal emittance due to reduced local view factors to the environment, and higher concentration ratios can be employed with similar surface irradiances to reduce the effective optical aperture, footprint, and thermal losses. Coupled optical/fluid/thermal models have been developed to evaluate the performance of these designs relative to conventional designs. Modeling results showed that fractal-like structures and geometries can increase the effective solar absorptance by 5 – 20% and the thermal efficiency by several percentage points at both the meso and macro scales, depending on factors such as intrinsic absorptance. Meso-scale prototypes were fabricated using additive manufacturing techniques, and a macro-scale bladed receiver design was fabricated using Inconel 625 tubes. On-sun tests were performed using the solar furnace and solar tower at the National Solar Thermal Test facility. The test results demonstrated enhanced solar absorptance and thermal efficiency of the fractal-like designs. 1. Empirical Analysis of High Efficient Remote Cloud Data Center Backup Using HBase and Cassandra OpenAIRE Chang, Bao Rong; Tsai, Hsiu-Fen; Chen, Chia-Yen; Guo, Cin-Long 2015-01-01 HBase, a master-slave framework, and Cassandra, a peer-to-peer (P2P) framework, are the two most commonly used large-scale distributed NoSQL databases, especially applicable to the cloud computing with high flexibility and scalability and the ease of big data processing. Regarding storage structure, different structure adopts distinct backup strategy to reduce the risks of data loss. This paper aims to realize high efficient remote cloud data center backup using HBase and Cassandra, and in or... 2. Efficient Four-Parametric with-and-without-Memory Iterative Methods Possessing High Efficiency Indices Directory of Open Access Journals (Sweden) Alicia Cordero 2018-01-01 Full Text Available We construct a family of derivative-free optimal iterative methods without memory to approximate a simple zero of a nonlinear function. Error analysis demonstrates that the without-memory class has eighth-order convergence and is extendable to with-memory class. The extension of new family to the with-memory one is also presented which attains the convergence order 15.5156 and a very high efficiency index 15.51561/4≈1.9847. Some particular schemes of the with-memory family are also described. Numerical examples and some dynamical aspects of the new schemes are given to support theoretical results. 3. Impedance Matching Antenna-Integrated High-Efficiency Energy Harvesting Circuit Science.gov (United States) Shinki, Yuharu; Shibata, Kyohei; Mansour, Mohamed 2017-01-01 This paper describes the design of a high-efficiency energy harvesting circuit with an integrated antenna. The circuit is composed of series resonance and boost rectifier circuits for converting radio frequency power into boosted direct current (DC) voltage. The measured output DC voltage is 5.67 V for an input of 100 mV at 900 MHz. Antenna input impedance matching is optimized for greater efficiency and miniaturization. The measured efficiency of this antenna-integrated energy harvester is 60% for −4.85 dBm input power and a load resistance equal to 20 kΩ at 905 MHz. PMID:28763043 4. High Efficiency of Two Efficient QSDC with Authentication Is at the Cost of Their Security International Nuclear Information System (INIS) Su-Juan, Qin; Qiao-Yan, Wen; Luo-Ming, Meng; Fu-Chen, Zhu 2009-01-01 Two efficient protocols of quantum secure direct communication with authentication [Chin. Phys. Lett. 25 (2008) 2354] were recently proposed by Liu et al. to improve the efficiency of two protocols presented in [Phys. Rev. A 75 (2007) 026301] by four Pauli operations. We show that the high efficiency of the two protocols is at the expense of their security. The authenticator Trent can reach half the secret by a particular attack strategy in the first protocol. In the second protocol, not only Trent but also an eavesdropper outside can elicit half-information about the secret from the public declaration 5. Plutonium Finishing Plant (PFP) Waste Composition and High Efficiency Particulate Air Filter Loading Energy Technology Data Exchange (ETDEWEB) ZIMMERMAN, B.D. 2000-12-11 This analysis evaluates the effect of the Plutonium Finishing Plant (PFP) waste isotopic composition on Tank Farms Final Safety Analysis Report (FSAR) accidents involving high-efficiency particulate air (HEPA) filter failure in Double-Contained Receiver Tanks (DCRTs). The HEPA Filter Failure--Exposure to High Temperature or Pressure, and Steam Intrusion From Interfacing Systems accidents are considered. The analysis concludes that dose consequences based on the PFP waste isotopic composition are bounded by previous FSAR analyses. This supports USQD TF-00-0768. 6. A highly efficient graphene oxide absorber for Q-switched Nd:GdVO4 lasers International Nuclear Information System (INIS) Wang Yonggang; Wen Xiaoming; Tang Jau; Chen, Hou Ren; Hsieh, Wen Feng 2011-01-01 We demonstrated that graphene oxide material could be used as a highly efficient saturable absorber for the Q-switched Nd:GdVO 4 laser. A novel and low-cost graphene oxide (GO) absorber was fabricated by a vertical evaporation technique and high viscosity of polyvinyl alcohol (PVA) aqueous solution. A piece of GO/PVA absorber, a piece of round quartz, and an output coupler mirror were combined to be a sandwich structure passive component. Using such a structure, 104 ns pulses and 1.22 W average output power were obtained with the maximum pulse energy at 2 µJ and a slope efficiency of 17%. 7. Highly Efficient Reproducible Perovskite Solar Cells Prepared by Low-Temperature Processing Directory of Open Access Journals (Sweden) Hao Hu 2016-04-01 Full Text Available In this work, we describe the role of the different layers in perovskite solar cells to achieve reproducible, ~16% efficient perovskite solar cells. We used a planar device architecture with PEDOT:PSS on the bottom, followed by the perovskite layer and an evaporated C60 layer before deposition of the top electrode. No high temperature annealing step is needed, which also allows processing on flexible plastic substrates. Only the optimization of all of these layers leads to highly efficient and reproducible results. In this work, we describe the effects of different processing conditions, especially the influence of the C60 top layer on the device performance. 8. Gamma-ray spectrometer system with high efficiency and high resolution International Nuclear Information System (INIS) Moss, C.E.; Bernard, W.; Dowdy, E.J.; Garcia, C.; Lucas, M.C.; Pratt, J.C. 1983-01-01 Our gamma-ray spectrometer system, designed for field use, offers high efficiency and high resolution for safeguards applications. The system consists of three 40% high-purity germanium detectors and a LeCroy 3500 data acquisition system that calculates a composite spectrum for the three detectors. The LeCroy 3500 mainframe can be operated remotely from the detector array with control exercised through modems and the telephone system. System performance with a mixed source of 125 Sb, 154 Eu, and 155 Eu confirms the expected efficiency of 120% with the overall resolution showing little degradation over that of the worst detector 9. High Efficient Nanocomposite for Removal of Heavy Metals (Hg2+ and Pb2+ from Aqueous Solution Directory of Open Access Journals (Sweden) M. Ebadi 2016-01-01 Full Text Available In current work, CdS/black carbon nanocomposites were successfully synthesized with the aid of chestnut and cadmium nitrate as the starting reagents. Besides, the effects of preparation parameters such as reaction time, and precursor concentration on the morphology of products and removal of heavy metals (Hg+2, Pb+2 were studied by scanning electron microscopy images and batch adsorption mode. CdS/black carbon nanocomposite introduced as new and high efficient system for removal of heavy metal ions. The as-synthesized products were characterized by powder X-ray diffraction, scanning electron microscopy, and spectra energy dispersive analysis of X-ray. 10. Game-Theoretic Rate-Distortion-Complexity Optimization of High Efficiency Video Coding DEFF Research Database (Denmark) Ukhanova, Ann; Milani, Simone; Forchhammer, Søren 2013-01-01 profiles in order to tailor the computational load to the different hardware and power-supply resources of devices. In this work, we focus on optimizing the quantization parameter and partition depth in HEVC via a game-theoretic approach. The proposed rate control strategy alone provides 0.2 dB improvement......This paper presents an algorithm for rate-distortioncomplexity optimization for the emerging High Efficiency Video Coding (HEVC) standard, whose high computational requirements urge the need for low-complexity optimization algorithms. Optimization approaches need to specify different complexity... 11. High Efficiency Three-phase Power Factor Correction Rectifier using Wide Band-Gap Devices DEFF Research Database (Denmark) Kouchaki, Alireza Improving the conversion efficiency of power factor correction (PFC) rectifiers has become compelling due to their wide applications such as adjustable speed drives, uninterruptible power supplies (UPS), and battery chargers for electric vehicles (EVs). The attention to PFCs has increased even more....... Therefore, current controllers are also important to be investigated in this project. In this PhD research work, a comprehensive design of a two-level three-phase PFC rectifier using silicon-carbide (SiC) switches to achieve high efficiency is presented. The work is divided into two main parts: 1) Optimum... 12. Impedance Matching Antenna-Integrated High-Efficiency Energy Harvesting Circuit Directory of Open Access Journals (Sweden) Yuharu Shinki 2017-08-01 Full Text Available This paper describes the design of a high-efficiency energy harvesting circuit with an integrated antenna. The circuit is composed of series resonance and boost rectifier circuits for converting radio frequency power into boosted direct current (DC voltage. The measured output DC voltage is 5.67 V for an input of 100 mV at 900 MHz. Antenna input impedance matching is optimized for greater efficiency and miniaturization. The measured efficiency of this antenna-integrated energy harvester is 60% for −4.85 dBm input power and a load resistance equal to 20 kΩ at 905 MHz. 13. Impedance Matching Antenna-Integrated High-Efficiency Energy Harvesting Circuit. Science.gov (United States) Shinki, Yuharu; Shibata, Kyohei; Mansour, Mohamed; Kanaya, Haruichi 2017-08-01 This paper describes the design of a high-efficiency energy harvesting circuit with an integrated antenna. The circuit is composed of series resonance and boost rectifier circuits for converting radio frequency power into boosted direct current (DC) voltage. The measured output DC voltage is 5.67 V for an input of 100 mV at 900 MHz. Antenna input impedance matching is optimized for greater efficiency and miniaturization. The measured efficiency of this antenna-integrated energy harvester is 60% for -4.85 dBm input power and a load resistance equal to 20 kΩ at 905 MHz. 14. High-efficiency condenser of steam from a steam-gas mixture Science.gov (United States) Milman, O. O.; Krylov, V. S.; Ptakhin, A. V.; Kondratev, A. V.; Yankov, G. G. 2017-12-01 The design of a module for a high-efficiency condenser of steam with a high content (up to 15%) of noncondensable gases (NCGs) with a nearly constant steam-gas mixture (SGM) velocity during the condensation of steam has been developed. This module provides the possibility to estimate the operational efficiency of six condenser zones during the motion of steam from the inlet to the SGM suction point. Some results of the experimental tests of the pilot high-efficiency condenser module are presented. The dependence of the average heat transfer coefficient k¯ on the volumetric NCG concentration v¯ has been derived. It is shown that the high-efficiency condenser module can provide a moderate decrease in k¯ from 4400-4600 to 2600-2800 W/(m2 K) at v¯ ≈ 0.5-9.0%. The heat transfer coefficient distribution over different module zones at a heat duty close to its nominal value has been obtained. From this distribution, it can be seen that the average heat transfer coefficient decreases to 2600 W/(m2 K) at an NCG concentration v¯ = 7.5%, but the first condenser sections ( 1- 3) retain high values of k¯ at a level of no lower than 3200 W/(m2 K), and the last sections operate less well, having k¯ at a level of 1700 W/(m2 K). The dependence of the average heat transfer coefficient on the water velocity in condenser tubes has been obtained at a nearly nominal duty such that the extrapolation of this dependence to the water velocity of 2 m/s may be expected to give k¯ = 5000 W/(m2 K) for relatively pure steam, but an increase in k¯ at v¯ = 8% will be smaller. The effect of the gas removal device characteristic on the operation of the high-efficiency condenser module is described. The design developed for the steam condenser of a gas-turbine plant with a power of 25 MW, a steam flow rate of 40.2 t/h, and a CO2 concentration of up to 12% with consideration for the results of performed studies is presented. 15. Design, fabrication, and characterization of high-efficiency extreme ultraviolet diffusers Energy Technology Data Exchange (ETDEWEB) Naulleau, Patrick P.; Liddle, J. Alexander; Salmassi, Farhad; Anderson, Erik H.; Gullikson, Eric M. 2004-02-19 As the development of extreme ultraviolet (EUV) lithography progresses, interest grows in the extension of traditional optical components to the EUV regime. The strong absorption of EUV by most materials and its extremely short wavelength, however, makes it very difficult to implement many components that are commonplace in the longer wavelength regimes. One such example is the diffuser often implemented with ordinary ground glass in the visible light regime. Here we demonstrate the fabrication of reflective EUV diffusers with high efficiency within a controllable bandwidth. Using these techniques we have fabricated diffusers with efficiencies exceeding 10% within a moderate angular single-sided bandwidth of approximately 0.06 radians. 16. High efficiency and broad bandwidth grating coupler between nanophotonic waveguide and fibre International Nuclear Information System (INIS) Yu, Zhu; Xue-Jun, Xu; Zhi-Yong, Li; Liang, Zhou; Yu-De, Yu; Jin-Zhong, Yu; Wei-Hua, Han; Zhong-Chao, Fan 2010-01-01 A high efficiency and broad bandwidth grating coupler between a silicon-on-insulator (SOI) nanophotonic waveguide and fibre is designed and fabricated. Coupling efficiencies of 46% and 25% at a wavelength of 1.55 μm are achieved by simulation and experiment, respectively. An optical 3 dB bandwidth of 45 nm from 1530 nm to 1575 nm is also obtained in experiment. Numerical calculation shows that a tolerance to fabrication error of 10 nm in etch depth is achievable. The measurement results indicate that the alignment error of ±2 μm results in less than 1 dB additional coupling loss. (classical areas of phenomenology) 17. Highly Efficient Procedure for the Synthesis of Fructone Fragrance Using a Novel Carbon based Acid Directory of Open Access Journals (Sweden) Xuezheng Liang 2010-08-01 Full Text Available The novel carbon based acid has been synthesized via one-step hydrothermal carbonization of furaldehyde and hydroxyethylsulfonic acid. A highly efficient procedure for the synthesis of fructone has been developed using the novel carbon based acid. The results showed that the catalyst possessed high activity for the reaction, giving a yield of over 95%. The advantages of high activity, stability, reusability and low cost for a simple synthesis procedure and wide applicability to various diols and β-keto esters make this novel carbon based acid one of the best choices for the reaction. 18. Highly efficient holograms based on c-Si metasurfaces in the visible range. Science.gov (United States) Martins, Augusto; Li, Juntao; da Mota, Achiles F; Wang, Yin; Neto, Luiz G; do Carmo, João P; Teixeira, Fernando L; Martins, Emiliano R; Borges, Ben-Hur V 2018-04-16 This paper reports on the first hologram in transmission mode based on a c-Si metasurface in the visible range. The hologram shows high fidelity and high efficiency, with measured transmission and diffraction efficiencies of ~65% and ~40%, respectively. Although originally designed to achieve full phase control in the range [0-2π] at 532 nm, these holograms have also performed well at 444.9 nm and 635 nm. The high tolerance to both fabrication and wavelength variations demonstrate that holograms based on c-Si metasurfaces are quite attractive for diffractive optics applications, and particularly for full-color holograms. 19. Possibility of high efficient beam extraction from the CERN SPS with a bent crystal. Simulation results Energy Technology Data Exchange (ETDEWEB) Scandale, W. [CERN, European Organization for Nuclear Research, CH-1211 Geneva 23 (Switzerland); Laboratoire de l' AccelerateurLineaire (LAL), Universite Paris SudOrsay, Orsay (France); INFN Sezione di Roma, Piazzale Aldo Moro 2, 00185 Rome (Italy); Kovalenko, A.D.; Taratin, A.M. [Joint Institute for Nuclear Research, 141980 Dubna, Moscow Region (Russian Federation) 2017-03-11 The extraction of the SPS beam of 270 GeV/c protons assisted by a bent crystal was studied by simulation. Two methods for delivering the SPS beam onto a crystal were considered: transverse diffusion and orbit bump of the beam. It was shown that the main condition for high efficient beam extraction with a bent crystal, which is a small divergence of the incident beam, can be fulfilled. Extraction efficiency up to 99% can be reached for both methods of the beam delivering. The irradiation of the electrostatic septum wires during the beam extraction can be considerably reduced. 20. Generating power at high efficiency combined cycle technology for sustainable energy production CERN Document Server Jeffs, E 2008-01-01 Combined cycle technology is used to generate power at one of the highest levels of efficiency of conventional power plants. It does this through primary generation from a gas turbine coupled with secondary generation from a steam turbine powered by primary exhaust heat. Generating power at high efficiency thoroughly charts the development and implementation of this technology in power plants and looks to the future of the technology, noting the advantages of the most important technical features - including gas turbines, steam generator, combined heat and power and integrated gasification com 1. 2 W high efficiency PbS mid-infrared surface emitting laser Science.gov (United States) Ishida, A.; Sugiyama, Y.; Isaji, Y.; Kodama, K.; Takano, Y.; Sakata, H.; Rahim, M.; Khiar, A.; Fill, M.; Felder, F.; Zogg, H. 2011-09-01 High efficiency laser operation with output power exceeding 2 W was obtained for vertical external-cavity PbS based IV-VI compound surface emitting quantum-well structures. The laser showed external quantum efficiency as high as 16%. Generally, mid-infrared III-V or II-VI semiconductor laser operation utilizing interband electron transitions are restricted by Auger recombination and free carrier absorption. Auger recombination is much lower in the IV-VI semiconductors, and the free-carrier absorption is significantly reduced by an optically pumped laser structure including multi-step optical excitation layers. 2. High-Efficiency Low-Cost Solar Receiver for Use Ina a Supercritical CO2 Recompression Cycle Energy Technology Data Exchange (ETDEWEB) Sullivan, Shaun D. [Brayton Energy, LLC, Portsmouth, NH (United States); Kesseli, James [Brayton Energy, LLC, Portsmouth, NH (United States); Nash, James [Brayton Energy, LLC, Portsmouth, NH (United States); Farias, Jason [Brayton Energy, LLC, Portsmouth, NH (United States); Kesseli, Devon [Brayton Energy, LLC, Portsmouth, NH (United States); Caruso, William [Brayton Energy, LLC, Portsmouth, NH (United States) 2016-04-06 This project has performed solar receiver designs for two supercritical carbon dioxide (sCO2) power cycles. The first half of the program focused on a nominally 2 MWe power cycle, with a receiver designed for test at the Sandia Solar Thermal Test Facility. This led to an economical cavity-type receiver. The second half of the program focused on a 10 MWe power cycle, incorporating a surround open receiver. Rigorous component life and performance testing was performed in support of both receiver designs. The receiver performance objectives are set to conform to the US DOE goals of 6¢/kWh by 2020 . Key findings for both cavity-type and direct open receiver are highlighted below: A tube-based absorber design is impractical at specified temperatures, pressures and heat fluxes for the application; a plate-fin architecture however has been shown to meet performance and life targets; the148/kWth cost of the design is significantly less than the SunShot cost target with a margin of 30%; the proposed receiver design is scalable, and may be applied to both modular cavity-type installations as well as large utility-scale open receiver installations; the design may be integrated with thermal storage systems, allowing for continuous high-efficiency electrical production during off-sun hours; costs associated with a direct sCO2 receiver for a sCO2 Brayton power cycle are comparable to those of a typical molten salt receiver; lifetimes in excess of the 90,000 hour goal are achievable with an optimal cell geometry; the thermal performance of the Brayton receiver is significantly higher than the industry standard, and enables at least a 30% efficiency improvement over the performance of the baseline steam-Rankine boiler/cycle system; brayton’s patent-pending quartz tube window provides a greater than five-percent efficiency benefit to the receiver by reducing both convection and radiation losses.
3. Indocyanine green loaded graphene oxide for high-efficient photoacoustic tumor therapy
Directory of Open Access Journals (Sweden)
Baoyun Yan
2016-07-01
Full Text Available Photoacoustic therapy, using the photoacoustic effect of agents for selectively killing tumor cells, has shown promising for treating tumor. Utilization of high optical absorption probes can help to effectively improve the photoacoustic therapy efficiency. Herein, we report a novel high-absorption photoacoustic probe that is composed of indocyanine green (ICG and graphene oxide (GO, entitled GO-ICG, for photoacoustic therapy. The attached ICG with narrow absorption spectral profile has strong optical absorption in the infrared region. The absorption spectrum of the GO-ICG solution reveals that the GO-ICG particles exhibited a 10-fold higher absorbance at 780nm (its peak absorbance as compared with GO. Importantly, ICG’s fluorescence is quenched by GO via fluorescence resonance energy transfer. As a result, GO-ICG can high-efficiently convert the absorbed light energy to acoustic wave under pulsed laser irradiation. We further demonstrate that GO-ICG can produce stronger photoacoustic wave than the GO and ICG alone. Moreover, we conjugate this contrast agent with integrin αvβ3 mono-clonal antibody to molecularly target the U87-MG human glioblastoma cells for selective tumor cell killing. Finally, our results testify that the photoacoustic therapy efficiency of GO-ICG is higher than the existing photoacoustic therapy agent. Our work demonstrates that GO-ICG is a high-efficiency photoacoustic therapy agent. This novel photoacoustic probe is likely to be an available candidate for tumor therapy.
4. Bio-inspired multistructured conical copper wires for highly efficient liquid manipulation.
Science.gov (United States)
Wang, Qianbin; Meng, Qingan; Chen, Ming; Liu, Huan; Jiang, Lei
2014-09-23
Animal hairs are typical structured conical fibers ubiquitous in natural system that enable the manipulation of low viscosity liquid in a well-controlled manner, which serves as the fundamental structure in Chinese brush for ink delivery in a controllable manner. Here, drawing inspiration from these structure, we developed a dynamic electrochemical method that enables fabricating the anisotropic multiscale structured conical copper wire (SCCW) with controllable conicity and surface morphology. The as-prepared SCCW exhibits a unique ability for manipulating liquid with significantly high efficiency, and over 428 times greater than its own volume of liquid could be therefore operated. We propose that the boundary condition of the dynamic liquid balance behavior on conical fibers, namely, steady holding of liquid droplet at the tip region of the SCCW, makes it an excellent fibrous medium to manipulate liquid. Moreover, we demonstrate that the titling angle of the SCCW can also affect its efficiency of liquid manipulation by virtue of its mechanical rigidity, which is hardly realized by flexible natural hairs. We envision that the bio-inspired SCCW could give inspiration in designing materials and devices to manipulate liquid in a more controllable way and with high efficiency.
5. Empirical Analysis of High Efficient Remote Cloud Data Center Backup Using HBase and Cassandra
Directory of Open Access Journals (Sweden)
Bao Rong Chang
2015-01-01
Full Text Available HBase, a master-slave framework, and Cassandra, a peer-to-peer (P2P framework, are the two most commonly used large-scale distributed NoSQL databases, especially applicable to the cloud computing with high flexibility and scalability and the ease of big data processing. Regarding storage structure, different structure adopts distinct backup strategy to reduce the risks of data loss. This paper aims to realize high efficient remote cloud data center backup using HBase and Cassandra, and in order to verify the high efficiency backup they have applied Thrift Java for cloud data center to take a stress test by performing strictly data read/write and remote database backup in the large amounts of data. Finally, in terms of the effectiveness-cost evaluation to assess the remote datacenter backup, a cost-performance ratio has been evaluated for several benchmark databases and the proposed ones. As a result, the proposed HBase approach outperforms the other databases.
6. Novel concepts for high-efficiency white organic light-emitting diodes
Energy Technology Data Exchange (ETDEWEB)
Schwartz, Gregor
2007-07-01
This work deals with novel concepts to realize high efficiency white OLEDs by combining fluorescent blue and phosphorescent green and orange emitters. A key point determining the maximum efficiency possible, as well as the device structure to be chosen to reach high efficiency, is the triplet exciton energy of the fluorescent blue emitter. If its triplet state is lower than that of the phosphorescent emitters, mutual exciton quenching can occur. This problem is solved by the first concept with spatial separation of the fluorescent blue from the phosphorescent emitters by a large-gap exciton blocking layer. To still realize exciton generation on both sides, the interlayer has to be ambipolar. On the other hand, if the triplet exciton energy of the fluorescent blue is higher than that of at least one of the phosphorescent emitters, appropriate arrangement of the emission layers makes a separation layer obsolete, since phosphorescence quenching does not occur anymore. Moreover, the intrinsically non-radiative triplet excitons of the fluorescent blue emitter may be harvested by the phosphor for light emission, which means that even 100% internal quantum efficiency is possible. The last chapter 6 deals with this second concept, where the main issue is to simultaneously achieve exciton harvesting as complete as possible and a balanced white emission spectrum by appropriately distributing singlet and triplet excitons to the used emitters. All emitters used in this work are commercially available and their molecular structure is disclosed in order to make the results transparent. (orig.)
7. Highly efficient construction of oriented sandwich structures for surface-enhanced Raman scattering
International Nuclear Information System (INIS)
Guo Hongyun; Xu Weiqing; Xu Shuping; Zhou Ji; Lombardi, John R
2013-01-01
The purpose of this study is to solve the problem of low achievement in fabricating sandwich surface-enhanced Raman scattering (SERS) substrates. We demonstrated a highly efficient sandwich structure by the oriented assembly of metal nanoparticles (NPs) on a periodic hexagonal array of metal nanoprisms with 1,4-benzenedithiol (1,4-BDT) as linkers. The metal nanoprism array was prepared by vacuum deposition of metal on a close-packed polystyrene nanosphere pre-patterned substrate. The metal nanoprism array presents different surface properties from the pits left from the removal of polystyrene nanospheres, which causes linkers to selectively adsorb on the metal nanoprism array and sequentially leads to the oriented immobilization of the second-layer metal NPs, avoiding mismatched orientation. These sandwich SERS substrates were characterized by extinction spectroscopy and atomic force microscopy and their enhancement activity was evaluated under different excitation wavelengths. The sandwich structure greatly increases the achievement of ‘hot spots’ to almost 100% of all the metal nanoprisms and enables a large amplification of SERS signals by a factor of ten. This method has the advantages of simplicity, high efficiency, high throughput, controllability and high reproducibility. It has significance in both the study of SERS substrates and the development of plasmonic devices. (paper)
8. Long-duration heat load measurement approach by novel apparatus design and highly efficient algorithm
Science.gov (United States)
Zhu, Yanwei; Yi, Fajun; Meng, Songhe; Zhuo, Lijun; Pan, Weizhen
2017-11-01
Improving the surface heat load measurement technique for vehicles in aerodynamic heating environments is imperative, regarding aspects of both the apparatus design and identification efficiency. A simple novel apparatus is designed for heat load identification, taking into account the lessons learned from several aerodynamic heating measurement devices. An inverse finite difference scheme (invFDM) for the apparatus is studied to identify its surface heat flux from the interior temperature measurements with high efficiency. A weighted piecewise regression filter is also proposed for temperature measurement prefiltering. Preliminary verification of the invFDM scheme and the filter is accomplished via numerical simulation experiments. Three specific pieces of apparatus have been concretely designed and fabricated using different sensing materials. The aerodynamic heating process is simulated by an inductively coupled plasma wind tunnel facility. The identification of surface temperature and heat flux from the temperature measurements is performed by invFDM. The results validate the high efficiency, reliability and feasibility of heat load measurements with different heat flux levels utilizing the designed apparatus and proposed method.
9. A highly efficient approach to protein interactome mapping based on collaborative filtering framework.
Science.gov (United States)
Luo, Xin; You, Zhuhong; Zhou, Mengchu; Li, Shuai; Leung, Hareton; Xia, Yunni; Zhu, Qingsheng
2015-01-09
The comprehensive mapping of protein-protein interactions (PPIs) is highly desired for one to gain deep insights into both fundamental cell biology processes and the pathology of diseases. Finely-set small-scale experiments are not only very expensive but also inefficient to identify numerous interactomes despite their high accuracy. High-throughput screening techniques enable efficient identification of PPIs; yet the desire to further extract useful knowledge from these data leads to the problem of binary interactome mapping. Network topology-based approaches prove to be highly efficient in addressing this problem; however, their performance deteriorates significantly on sparse putative PPI networks. Motivated by the success of collaborative filtering (CF)-based approaches to the problem of personalized-recommendation on large, sparse rating matrices, this work aims at implementing a highly efficient CF-based approach to binary interactome mapping. To achieve this, we first propose a CF framework for it. Under this framework, we model the given data into an interactome weight matrix, where the feature-vectors of involved proteins are extracted. With them, we design the rescaled cosine coefficient to model the inter-neighborhood similarity among involved proteins, for taking the mapping process. Experimental results on three large, sparse datasets demonstrate that the proposed approach outperforms several sophisticated topology-based approaches significantly.
10. Highly Efficient Intracellular Protein Delivery by Cationic Polyethyleneimine-Modified Gelatin Nanoparticles
Directory of Open Access Journals (Sweden)
Ming-Ju Chou
2018-02-01
Full Text Available Intracellular protein delivery may provide a safe and non-genome integrated strategy for targeting abnormal or specific cells for applications in cell reprogramming therapy. Thus, highly efficient intracellular functional protein delivery would be beneficial for protein drug discovery. In this study, we generated a cationic polyethyleneimine (PEI-modified gelatin nanoparticle and evaluated its intracellular protein delivery ability in vitro and in vivo. The experimental results showed that the PEI-modified gelatin nanoparticle had a zeta potential of approximately +60 mV and the particle size was approximately 135 nm. The particle was stable at different biological pH values and temperatures and high protein loading efficiency was observed. The fluorescent image results revealed that large numbers of particles were taken up into the mammalian cells and escaped from the endosomes into the cytoplasm. In a mouse C26 cell-xenograft cancer model, particles accumulated in cancer cells. In conclusion, the PEI-modified gelatin particle may provide a biodegradable and highly efficient protein delivery system for use in regenerative medicine and cancer therapy.
11. Ultra-high efficiency photovoltaic cells for large scale solar power generation.
Science.gov (United States)
Nakano, Yoshiaki
2012-01-01
The primary targets of our project are to drastically improve the photovoltaic conversion efficiency and to develop new energy storage and delivery technologies. Our approach to obtain an efficiency over 40% starts from the improvement of III-V multi-junction solar cells by introducing a novel material for each cell realizing an ideal combination of bandgaps and lattice-matching. Further improvement incorporates quantum structures such as stacked quantum wells and quantum dots, which allow higher degree of freedom in the design of the bandgap and the lattice strain. Highly controlled arrangement of either quantum dots or quantum wells permits the coupling of the wavefunctions, and thus forms intermediate bands in the bandgap of a host material, which allows multiple photon absorption theoretically leading to a conversion efficiency exceeding 50%. In addition to such improvements, microfabrication technology for the integrated high-efficiency cells and the development of novel material systems that realizes high efficiency and low cost at the same time are investigated.
12. Light-induced lattice expansion leads to high-efficiency perovskite solar cells
Energy Technology Data Exchange (ETDEWEB)
Tsai, Hsinhan; Asadpour, Reza; Blancon, Jean-Christophe; Stoumpos, Constantinos C.; Durand, Olivier; Strzalka, Joseph W.; Chen, Bo; Verduzco, Rafael; Ajayan, Pulickel M.; Tretiak, Sergei; Even, Jacky; Alam, Muhammad Ashraf; Kanatzidis, Mercouri G.; Nie, Wanyi; Mohite, Aditya D.
2018-04-05
Hybrid-perovskite based high-performance optoelectronic devices and clues from their operation has led to the realization that light-induced structural dynamics play a vital role on their physical properties, device performance and stability. Here, we report that continuous light illumination leads to a uniform lattice expansion in hybrid perovskite thin-films, which is critical for obtaining high-efficiency photovoltaic devices. Correlated, in-situ structural and device characterizations reveal that light-induced lattice expansion significantly benefits the performances of a mixed-cation pure-halide planar device, boosting the power conversion efficiency from 18.5% to 20.5%. This is a direct consequence of the relaxation of local lattice strains during lattice expansion, which results in the reduction of the energetic barriers at the perovskite/contact interfaces in devices, thus improving the open circuit voltage and fill factor. The light-induced lattice expansion stabilizes these high-efficiency photovoltaic devices under continuous operation of full-spectrum 1-Sun illumination for over 1500 hours. One Sentence Summary: Light-induced lattice expansion improves crystallinity, relaxes lattice strain, which enhances photovoltaic performance in hybrid perovskite device.
13. Facile and high-efficient immobilization of histidine-tagged multimeric protein G on magnetic nanoparticles
Science.gov (United States)
Lee, Jiho; Chang, Jeong Ho
2014-12-01
This work reports the high-efficient and one-step immobilization of multimeric protein G on magnetic nanoparticles. The histidine-tagged (His-tag) recombinant multimeric protein G was overexpressed in Escherichia coli BL21 by the repeated linking of protein G monomers with a flexible linker. High-efficient immobilization on magnetic nanoparticles was demonstrated by two different preparation methods through the amino-silane and chloro-silane functionalization on silica-coated magnetic nanoparticles. Three kinds of multimeric protein G such as His-tag monomer, dimer, and trimer were tested for immobilization efficiency. For these tests, bicinchoninic acid (BCA) assay was employed to determine the amount of immobilized His-tag multimeric protein G. The result showed that the immobilization efficiency of the His-tag multimeric protein G of the monomer, dimer, and trimer was increased with the use of chloro-silane-functionalized magnetic nanoparticles in the range of 98% to 99%, rather than the use of amino-silane-functionalized magnetic nanoparticles in the range of 55% to 77%, respectively.
14. A High-Efficiency Wind Energy Harvester for Autonomous Embedded Systems.
Science.gov (United States)
Brunelli, Davide
2016-03-04
Energy harvesting is currently a hot research topic, mainly as a consequence of the increasing attractiveness of computing and sensing solutions based on small, low-power distributed embedded systems. Harvesting may enable systems to operate in a deploy-and-forget mode, particularly when power grid is absent and the use of rechargeable batteries is unattractive due to their limited lifetime and maintenance requirements. This paper focuses on wind flow as an energy source feasible to meet the energy needs of a small autonomous embedded system. In particular the contribution is on the electrical converter and system integration. We characterize the micro-wind turbine, we define a detailed model of its behaviour, and then we focused on a highly efficient circuit to convert wind energy into electrical energy. The optimized design features an overall volume smaller than 64 cm³. The core of the harvester is a high efficiency buck-boost converter which performs an optimal power point tracking. Experimental results show that the wind generator boosts efficiency over a wide range of operating conditions.
15. Long-duration heat load measurement approach by novel apparatus design and highly efficient algorithm
International Nuclear Information System (INIS)
Zhu, Yanwei; Yi, Fajun; Meng, Songhe; Zhuo, Lijun; Pan, Weizhen
2017-01-01
Improving the surface heat load measurement technique for vehicles in aerodynamic heating environments is imperative, regarding aspects of both the apparatus design and identification efficiency. A simple novel apparatus is designed for heat load identification, taking into account the lessons learned from several aerodynamic heating measurement devices. An inverse finite difference scheme (invFDM) for the apparatus is studied to identify its surface heat flux from the interior temperature measurements with high efficiency. A weighted piecewise regression filter is also proposed for temperature measurement prefiltering. Preliminary verification of the invFDM scheme and the filter is accomplished via numerical simulation experiments. Three specific pieces of apparatus have been concretely designed and fabricated using different sensing materials. The aerodynamic heating process is simulated by an inductively coupled plasma wind tunnel facility. The identification of surface temperature and heat flux from the temperature measurements is performed by invFDM. The results validate the high efficiency, reliability and feasibility of heat load measurements with different heat flux levels utilizing the designed apparatus and proposed method. (paper)
16. Dynamical Origin of Highly Efficient Energy Dissipation in Soft Magnetic Nanoparticles for Magnetic Hyperthermia Applications
Science.gov (United States)
Kim, Min-Kwan; Sim, Jaegun; Lee, Jae-Hyeok; Kim, Miyoung; Kim, Sang-Koog
2018-05-01
We explore robust magnetization-dynamic behaviors in soft magnetic nanoparticles in single-domain states and find their related high-efficiency energy-dissipation mechanism using finite-element micromagnetic simulations. We also make analytical derivations that provide deeper physical insights into the magnetization dynamics associated with Gilbert damping parameters under applications of time-varying rotating magnetic fields of different strengths and frequencies and static magnetic fields. Furthermore, we find that the mass-specific energy-dissipation rate at resonance in the steady-state regime changes remarkably with the strength of rotating fields and static fields for given damping constants. The associated magnetization dynamics are well interpreted with the help of the numerical calculation of analytically derived explicit forms. The high-efficiency energy-loss power can be obtained using soft magnetic nanoparticles in the single-domain state by tuning the frequency of rotating fields to the resonance frequency; what is more, it is controllable via the rotating and static field strengths for a given intrinsic damping constant. We provide a better and more efficient means of achieving specific loss power that can be implemented in magnetic hyperthermia applications.
17. High-efficiency and low-loss gallium nitride dielectric metasurfaces for nanophotonics at visible wavelengths
Science.gov (United States)
Emani, Naresh Kumar; Khaidarov, Egor; Paniagua-Domínguez, Ramón; Fu, Yuan Hsing; Valuckas, Vytautas; Lu, Shunpeng; Zhang, Xueliang; Tan, Swee Tiam; Demir, Hilmi Volkan; Kuznetsov, Arseniy I.
2017-11-01
The dielectric nanophotonics research community is currently exploring transparent material platforms (e.g., TiO2, Si3N4, and GaP) to realize compact high efficiency optical devices at visible wavelengths. Efficient visible-light operation is key to integrating atomic quantum systems for future quantum computing. Gallium nitride (GaN), a III-V semiconductor which is highly transparent at visible wavelengths, is a promising material choice for active, nonlinear, and quantum nanophotonic applications. Here, we present the design and experimental realization of high efficiency beam deflecting and polarization beam splitting metasurfaces consisting of GaN nanostructures etched on the GaN epitaxial substrate itself. We demonstrate a polarization insensitive beam deflecting metasurface with 64% and 90% absolute and relative efficiencies. Further, a polarization beam splitter with an extinction ratio of 8.6/1 (6.2/1) and a transmission of 73% (67%) for p-polarization (s-polarization) is implemented to demonstrate the broad functionality that can be realized on this platform. The metasurfaces in our work exhibit a broadband response in the blue wavelength range of 430-470 nm. This nanophotonic platform of GaN shows the way to off- and on-chip nonlinear and quantum photonic devices working efficiently at blue emission wavelengths common to many atomic quantum emitters such as Ca+ and Sr+ ions.
18. Industrially feasible, dopant-free, carrier-selective contacts for high-efficiency silicon solar cells
KAUST Repository
Yang, Xinbo
2017-05-31
Dopant-free, carrier-selective contacts (CSCs) on high efficiency silicon solar cells combine ease of deposition with potential optical benefits. Electron-selective titanium dioxide (TiO) contacts, one of the most promising dopant-free CSC technologies, have been successfully implemented into silicon solar cells with an efficiency over 21%. Here, we report further progress of TiO contacts for silicon solar cells and present an assessment of their industrial feasibility. With improved TiO contact quality and cell processing, a remarkable efficiency of 22.1% has been achieved using an n-type silicon solar cell featuring a full-area TiO contact. Next, we demonstrate the compatibility of TiO contacts with an industrial contact-firing process, its low performance sensitivity to the wafer resistivity, its applicability to ultrathin substrates as well as its long-term stability. Our findings underscore the great appeal of TiO contacts for industrial implementation with their combination of high efficiency with robust fabrication at low cost.
19. A High-Efficiency Wind Energy Harvester for Autonomous Embedded Systems
Science.gov (United States)
Brunelli, Davide
2016-01-01
Energy harvesting is currently a hot research topic, mainly as a consequence of the increasing attractiveness of computing and sensing solutions based on small, low-power distributed embedded systems. Harvesting may enable systems to operate in a deploy-and-forget mode, particularly when power grid is absent and the use of rechargeable batteries is unattractive due to their limited lifetime and maintenance requirements. This paper focuses on wind flow as an energy source feasible to meet the energy needs of a small autonomous embedded system. In particular the contribution is on the electrical converter and system integration. We characterize the micro-wind turbine, we define a detailed model of its behaviour, and then we focused on a highly efficient circuit to convert wind energy into electrical energy. The optimized design features an overall volume smaller than 64 cm3. The core of the harvester is a high efficiency buck-boost converter which performs an optimal power point tracking. Experimental results show that the wind generator boosts efficiency over a wide range of operating conditions. PMID:26959018
20. Highly efficient and selective pressure-assisted photon-induced polymerization of styrene
Energy Technology Data Exchange (ETDEWEB)
Guan, Jiwen [Department of Physics and Astronomy, University of Western Ontario, London, Ontario N6A 3K7 (Canada); Song, Yang, E-mail: yang.song@uwo.ca [Department of Physics and Astronomy, University of Western Ontario, London, Ontario N6A 3K7 (Canada); Department of Chemistry, University of Western Ontario, London, Ontario N6A 5B7 (Canada)
2016-06-07
The polymerization process of condensed styrene to produce polystyrene as an industrially important polymeric material was investigated using a novel approach by combining external compression with ultraviolet radiation. The reaction evolution was monitored as a function of time and the reaction products were characterized by in situ Fourier transform infrared spectroscopy. By optimizing the loading pressures, we observed highly efficient and selective production of polystyrene of different tacticities. Specifically, at relatively low loading pressures, infrared spectra suggest that styrene monomers transform to amorphous atactic polystyrene (APS) with minor crystalline isotactic polystyrene. In contrast, APS was found to be the sole product when polymerization occurs at relatively higher loading pressures. The time-dependent reaction profiles allow the examination of the polymerization kinetics by analyzing the rate constant and activation volume as a function of pressure. As a result, an optimized pressure condition, which allows a barrierless reaction to proceed, was identified and attributed to the very desirable reaction yield and kinetics. Finally, the photoinitiated reaction mechanism and the growth geometry of the polymer chains were investigated from the energy diagram of styrene and by the topology analysis of the crystal styrene. This study shows strong promise to produce functional polymeric materials in a highly efficient and controlled manner.
1. High-efficiency optical pumping of nuclear polarization in a GaAs quantum well
Science.gov (United States)
Mocek, R. W.; Korenev, V. L.; Bayer, M.; Kotur, M.; Dzhioev, R. I.; Tolmachev, D. O.; Cascio, G.; Kavokin, K. V.; Suter, D.
2017-11-01
The dynamic polarization of nuclear spins by photoexcited electrons is studied in a high quality GaAs/AlGaAs quantum well. We find a surprisingly high efficiency of the spin transfer from the electrons to the nuclei as reflected by a maximum nuclear field of 0.9 T in a tilted external magnetic field of 1 T strength only. This high efficiency is due to a low leakage of spin out of the polarized nuclear system, because mechanisms of spin relaxation other than the hyperfine interaction are strongly suppressed, leading to a long nuclear relaxation time of up to 1000 s. A key ingredient to that end is the low impurity concentration inside the heterostructure, while the electrostatic potential from charged impurities in the surrounding barriers becomes screened through illumination by which the spin relaxation time is increased compared to keeping the system in the dark. This finding indicates a strategy for obtaining high nuclear spin polarization as required for long-lasting carrier spin coherence.
2. High efficiency class-I audio power amplifier using a single adaptive supply
International Nuclear Information System (INIS)
Peng Zhenfei; Yang Shanshand; Feng Yong; Hong Zhiliang; Liu Yang
2012-01-01
A high efficiency class-I linear audio power amplifier (PA) with an adaptive supply is presented. Its efficiency is improved by a dynamic supply to reduce the power transistors' voltage drop. A gain compression technique is adopted to make the amplifier accommodate a single positive supply. Circuit complicity and chip area are reduced because no charge pump is necessary for the negative supply. A common shared mode voltage and a symmetric layout pattern are used to minimize the non-linearity. A peak efficiency of 80% is reached at peak output power. The measured THD+N before and after the supply switching point are 0.01% and 0.05%, respectively. The maximum output power is 410 mW for an 8 Ω speaker load. Unlike switching amplifiers, the class-I amplifier operates as a linear amplifier and hence has a low EMI. The advantage of a high efficiency and low EMI makes the class-I amplifier suitable for portable and RF sensitive applications. (semiconductor integrated circuits)
3. Research on High-efficient Remanufacturing Technologies and Application of Electric Motor
Science.gov (United States)
Liu, Ren; Zhao, Yuejin; Yang, Xu; Wang, Gen
2017-09-01
The energy conservation of electric motor system is the key of industrial energy conservation. With the implementation and acceleration of electric motor energy efficiency improvement plan, more and more electric motors are knocked out. High-efficient remanufacturing of electric motor refers to improving the efficiency of electric motor and recycling the resources by replacing the winding, iron core and other components of electric motor on the basis of the low-efficient/outdated electric motors, which conforms to China’s policy of circular economy and resource recovery. The remanufacturing of electric motor not only maximizes the use of resources, but also reduces the energy consumption generated by reprocessing of cast iron, silicon steel sheet and other materials in dismantling of electric motor. However, structures and iron core materials used in design and manufacture of electric motors are different, and the degrees of wear of electric motors are also different under different operating conditions, which further result in diversified design schemes, increased remanufacturing cost and reduced remanufacturing efficiency. This paper analyzes the key process technologies for remanufacturing of electric motors are researched by analyzing the remanufacturing technologies of electric motors, and presents the feasibility to replace the cast-aluminum rotor with cast-copper rotor in high-efficient remanufacturing process of electric motor.
4. Efficiency and Loading Evaluation of High Efficiency Mist Eliminators (HEME) - 12003
Energy Technology Data Exchange (ETDEWEB)
Giffin, Paxton K.; Parsons, Michael S.; Waggoner, Charles A. [Institute for Clean Energy Technology, Mississippi State University, 205 Research Blvd Starkville, MS 39759 (United States)
2012-07-01
High efficiency mist eliminators (HEME) are filters primarily used to remove moisture and/or liquid aerosols from an air stream. HEME elements are designed to reduce aerosol and particulate load on primary High Efficiency Particulate Air (HEPA) filters and to have a liquid particle removal efficiency of approximately 99.5% for aerosols down to sub-micron size particulates. The investigation presented here evaluates the loading capacity of the element in the absence of a water spray cleaning system. The theory is that without the cleaning system, the HEME element will suffer rapid buildup of solid aerosols, greatly reducing the particle loading capacity. Evaluation consists of challenging the element with a waste surrogate dry aerosol and di-octyl phthalate (DOP) at varying intervals of differential pressure to examine the filtering efficiency of three different element designs at three different media velocities. Also, the elements are challenged with a liquid waste surrogate using Laskin nozzles and large dispersion nozzles. These tests allow the loading capacity of the unit to be determined and the effectiveness of washing down the interior of the elements to be evaluated. (authors)
5. Innovative-Simplified Nuclear Power Plant Efficiency Evaluation with High-Efficiency Steam Injector System
International Nuclear Information System (INIS)
Shoji, Goto; Shuichi, Ohmori; Michitsugu, Mori
2006-01-01
It is possible to establish simplified system with reduced space and total equipment weight using high-efficiency Steam Injectors (SI) instead of low-pressure feedwater heaters in Nuclear Power Plant (NPP). The SI works as a heat exchanger through direct contact between feedwater from condensers and extracted steam from turbines. It can get higher pressure than supplied steam pressure. The maintenance and reliability are still higher than the feedwater ones because SI has no movable parts. This paper describes the analysis of the heat balance, plant efficiency and the operation of this Innovative-Simplified NPP with high-efficiency SI. The plant efficiency and operation are compared with the electric power of 1100 MWe-class BWR system and the Innovative-Simplified BWR system with SI. The SI model is adapted into the heat balance simulator with a simplified model. The results show that plant efficiencies of the Innovated-Simplified BWR system are almost equal to original BWR ones. The present research is one of the projects that are carried out by Tokyo Electric Power Company, Toshiba Corporation, and six Universities in Japan, funded from the Institute of Applied Energy (IAE) of Japan as the national public research-funded program. (authors)
6. Highly efficient star formation in NGC 5253 possibly from stream-fed accretion.
Science.gov (United States)
Turner, J L; Beck, S C; Benford, D J; Consiglio, S M; Ho, P T P; Kovács, A; Meier, D S; Zhao, J-H
2015-03-19
Gas clouds in present-day galaxies are inefficient at forming stars. Low star-formation efficiency is a critical parameter in galaxy evolution: it is why stars are still forming nearly 14 billion years after the Big Bang and why star clusters generally do not survive their births, instead dispersing to form galactic disks or bulges. Yet the existence of ancient massive bound star clusters (globular clusters) in the Milky Way suggests that efficiencies were higher when they formed ten billion years ago. A local dwarf galaxy, NGC 5253, has a young star cluster that provides an example of highly efficient star formation. Here we report the detection of the J = 3→2 rotational transition of CO at the location of the massive cluster. The gas cloud is hot, dense, quiescent and extremely dusty. Its gas-to-dust ratio is lower than the Galactic value, which we attribute to dust enrichment by the embedded star cluster. Its star-formation efficiency exceeds 50 per cent, tenfold that of clouds in the Milky Way. We suggest that high efficiency results from the force-feeding of star formation by a streamer of gas falling into the galaxy.
7. A High-Efficiency Wind Energy Harvester for Autonomous Embedded Systems
Directory of Open Access Journals (Sweden)
Davide Brunelli
2016-03-01
Full Text Available Energy harvesting is currently a hot research topic, mainly as a consequence of the increasing attractiveness of computing and sensing solutions based on small, low-power distributed embedded systems. Harvesting may enable systems to operate in a deploy-and-forget mode, particularly when power grid is absent and the use of rechargeable batteries is unattractive due to their limited lifetime and maintenance requirements. This paper focuses on wind flow as an energy source feasible to meet the energy needs of a small autonomous embedded system. In particular the contribution is on the electrical converter and system integration. We characterize the micro-wind turbine, we define a detailed model of its behaviour, and then we focused on a highly efficient circuit to convert wind energy into electrical energy. The optimized design features an overall volume smaller than 64 cm3. The core of the harvester is a high efficiency buck-boost converter which performs an optimal power point tracking. Experimental results show that the wind generator boosts efficiency over a wide range of operating conditions.
8. High-efficiency combinatorial approach as an effective tool for accelerating metallic biomaterials research and discovery
Energy Technology Data Exchange (ETDEWEB)
Zhang, X.D. [School of Material Science and Engineering, Central South University, Changsha, Hunan, 410083 (China); Liu, L.B., E-mail: lbliu.csu@gmail.com [School of Material Science and Engineering, Central South University, Changsha, Hunan, 410083 (China); State Key Laboratory for Powder Metallurgy, Changsha, Hunan, 410083 (China); Zhao, J.-C. [State Key Laboratory for Powder Metallurgy, Changsha, Hunan, 410083 (China); Department of Materials Science and Engineering, The Ohio State University, 2041 College Road, Columbus, OH 43210 (United States); Wang, J.L.; Zheng, F.; Jin, Z.P. [School of Material Science and Engineering, Central South University, Changsha, Hunan, 410083 (China)
2014-06-01
A high-efficiency combinatorial approach has been applied to rapidly build the database of composition-dependent elastic modulus and hardness of the Ti–Ta and Ti–Zr–Ta systems. A diffusion multiple of the Ti–Zr–Ta system was manufactured, then annealed at 1173 K for 1800 h, and water quenched to room temperature. Extensive interdiffusion among Ti, Zr and Ta has taken place. Combining nanoindentation and electron probe micro-analysis (EPMA), the elastic modulus, hardness as well as composition across the diffusion multiple were determined. The composition/elastic modulus/hardness relationship of the Ti–Ta and Ti–Zr–Ta alloys has been obtained. It was found that the elastic modulus and hardness depend strongly on the Ta and Zr content. The result can be used to accelerate the discovery/development of bio-titanium alloys for different components in implant prosthesis. - Highlights: • High-efficiency diffusion multiple of Ti–Zr–Ta was manufactured. • Composition-dependent elastic modulus and hardness of the Ti–Ta and Ti–Zr–Ta systems have been obtained effectively, • The methodology and the information can be used to accelerate the discovery/development of bio-titanium alloys.
9. High-Efficiency Multiscale Modeling of Cell Deformations in Confined Microenvironments in Microcirculation and Microfluidic Devices
Science.gov (United States)
Lu, Huijie; Peng, Zhangli
2017-11-01
Our goal is to develop a high-efficiency multiscale modeling method to predict the stress and deformation of cells during the interactions with their microenvironments in microcirculation and microfluidic devices, including red blood cells (RBCs) and circulating tumor cells (CTCs). There are more than 1 billion people in the world suffering from RBC diseases, e.g. anemia, sickle cell diseases, and malaria. The mechanical properties of RBCs are changed in these diseases due to molecular structure alternations, which is not only important for understanding the disease pathology but also provides an opportunity for diagnostics. On the other hand, the mechanical properties of cancer cells are also altered compared to healthy cells. This can lead to acquired ability to cross the narrow capillary networks and endothelial gaps, which is crucial for metastasis, the leading cause of cancer mortality. Therefore, it is important to predict the deformation and stress of RBCs and CTCs in microcirculations. We are developing a high-efficiency multiscale model of cell-fluid interaction to study these two topics.
10. Dual-band and high-efficiency polarization converter based on metasurfaces at microwave frequencies
Science.gov (United States)
Liu, Yajun; Xia, Song; Shi, Hongyu; Zhang, Anxue; Xu, Zhuo
2016-06-01
We present a dual-band and high-efficiency polarization converter in microwave regime. The proposed converter can convert a linearly polarized wave to its cross-polarized wave for two distinct bands: Ku (11.5-20.0 GHz) and Ka (28.8-34.0 GHz). It can also convert the linearly polarized wave to a circularly polarized wave at four other frequencies. The experimental results are in good agreement with simulation results for both frequency bands. The polarization conversion ratio is above 0.94 for the Ku-band and 0.90 for the Ka-band. Furthermore, the converter can achieve dual-band and high-efficiency polarization conversion over angles of incidence up to 45°. The converter is also polarization-selective in that only the x- and y-polarized waves can be converted. The physical mechanism of the dual-band polarization conversion effect is interpreted via decomposed electric field components that couple with different plasmon resonance modes of the structure.
11. Highly efficient white organic light-emitting devices consisting of undoped ultrathin yellow phosphorescent layer
Energy Technology Data Exchange (ETDEWEB)
Liu, Shengqiang [State Key Laboratory of Electronic Thin Films and Integrated Devices, School of Optoelectronic Information, University of Electronic Science and Technology of China (UESTC), Chengdu 610054 (China); Yu, Junsheng, E-mail: jsyu@uestc.edu.cn [State Key Laboratory of Electronic Thin Films and Integrated Devices, School of Optoelectronic Information, University of Electronic Science and Technology of China (UESTC), Chengdu 610054 (China); Ma, Zhu; Zhao, Juan [State Key Laboratory of Electronic Thin Films and Integrated Devices, School of Optoelectronic Information, University of Electronic Science and Technology of China (UESTC), Chengdu 610054 (China)
2013-02-15
High-efficiency white organic light-emitting devices (WOLEDs) based on an undoped ultrathin yellow light-emitting layer and a doped blue light-emitting layer were demonstrated. While the thickness of blue light-emitting layer, formed by doping a charge-trapping phosphor, iridium(III) bis(4 Prime ,6 Prime -difluorophenylpyridinato)tetrakis(1-pyrazolyl)borate (FIr6) in a wide bandgap host, was kept constant, the thickness of neat yellow emissive layer of novel phosphorescent material, bis[2-(4-tertbutylphenyl)benzothiazolato-N,C{sup 2 Prime }]iridium (acetylacetonate) [(t-bt){sub 2}Ir(acac)] was varied to optimize the device performance. The optimized device exhibited maximum luminance, current efficiency and power efficiency of 24,000 cd/m{sup 2} (at 15.2 V), 79.0 cd/A (at 1550 cd/m{sup 2}) and 40.5 lm/W (at 1000 cd/m{sup 2}), respectively. Besides, the white-light emission covered a wide range of visible spectrum, and the Commission Internationale de l'Eclairage coordinates were (0.32, 0.38) with a color temperature of 5800 K at 8 V. Moreover, high external quantum efficiency was also obtained in the high-efficiency WOLEDs. The performance enhancement was attributed to the proper thickness of (t-bt){sub 2}Ir(acac) layer that enabled adequate current density and enough phosphorescent dye to trap electrons. - Highlights: Black-Right-Pointing-Pointer Highly efficient WOLEDs based on two complementary layers were fabricated. Black-Right-Pointing-Pointer The yellow emissive layer was formed by utilizing undoping system. Black-Right-Pointing-Pointer The blue emissive layer was made by host-guest doping system. Black-Right-Pointing-Pointer The thickness of the yellow emissive layer was varied to make device optimization. Black-Right-Pointing-Pointer The optimized device achieved high power efficiency of 40.5 lm/W.
12. Molecular design toward highly efficient photovoltaic polymers based on two-dimensional conjugated benzodithiophene.
Science.gov (United States)
Ye, Long; Zhang, Shaoqing; Huo, Lijun; Zhang, Maojie; Hou, Jianhui
2014-05-20
As researchers continue to develop new organic materials for solar cells, benzo[1,2-b:4,5-b']dithiophene (BDT)-based polymers have come to the fore. To improve the photovoltaic properties of BDT-based polymers, researchers have developed and applied various strategies leading to the successful molecular design of highly efficient photovoltaic polymers. Novel polymer materials composed of two-dimensional conjugated BDT (2D-conjugated BDT) have boosted the power conversion efficiency of polymer solar cells (PSCs) to levels that exceed 9%. In this Account, we summarize recent progress related to the design and synthesis of 2D-conjugated BDT-based polymers and discuss their applications in highly efficient photovoltaic devices. We introduce the basic considerations for the construction of 2D-conjugated BDT-based polymers and systematic molecular design guidelines. For example, simply modifying an alkoxyl-substituted BDT to form an alkylthienyl-substituted BDT can improve the polymer hole mobilities substantially with little effect on their molecular energy level. Secondly, the addition of a variety of chemical moieties to the polymer can produce a 2D-conjugated BDT unit with more functions. For example, the introduction of a conjugated side chain with electron deficient groups (such as para-alkyl-phenyl, meta-alkoxyl-phenyl, and 2-alkyl-3-fluoro-thienyl) allowed us to modulate the molecular energy levels of 2D-conjugated BDT-based polymers. Through the rational design of BDT analogues such as dithienobenzodithiophene (DTBDT) or the insertion of larger π bridges, we can tune the backbone conformations of these polymers and modulate their photovoltaic properties. We also discuss the influence of 2D-conjugated BDT on polymer morphology and the blends of these polymers with phenyl-C61 (or C71)-butyric acid methyl ester (PCBM). Finally, we summarize the various applications of the 2D-conjugated BDT-based polymers in highly efficient PSC devices. Overall, this Account
13. Thermoeconomic analysis of a novel zero-CO{sub 2}-emission high-efficiency power cycle using LNG coldness
Energy Technology Data Exchange (ETDEWEB)
Liu, Meng [China National Institute of Standardization, Beijing 100088 (China); Lior, Noam [Department of Mechanical Engineering and Applied Mechanics, University of Pennsylvania, Philadelphia, PA 19104-6315 (United States); Zhang, Na; Han, Wei [Institute of Engineering Thermophysics, Chinese Academy of Sciences, P.O. Box 2706, Beijing 100190 (China)
2009-11-15
This paper presents a thermoeconomic analysis aimed at the optimization of a novel zero-CO{sub 2} and other emissions and high-efficiency power and refrigeration cogeneration system, COOLCEP-S (Patent pending), which uses the liquefied natural gas (LNG) coldness during its revaporization. It was predicted that at the turbine inlet temperature (TIT) of 900 C, the energy efficiency of the COOLCEP-S system reaches 59%. The thermoeconomic analysis determines the specific cost, the cost of electricity, the system payback period and the total net revenue. The optimization started by performing a thermodynamic sensitivity analysis, which has shown that for a fixed TIT and pressure ratio, the pinch point temperature difference in the recuperator, {delta}T{sub p1}, and that in the condenser, {delta}T{sub p2} are the most significant unconstrained variables to have a significant effect on the thermal performance of novel cycle. The payback period of this novel cycle (with fixed net power output of 20 MW and plant life of 40 years) was {proportional_to}5.9 years at most, and would be reduced to {proportional_to}3.1 years at most when there is a market for the refrigeration byproduct. The capital investment cost of the economically optimized plant is estimated to be about 1000 /kWe, and the cost of electricity is estimated to be 0.34-0.37 CNY/kWh ({proportional_to}0.04 USD/kWh). These values are much lower than those of conventional coal power plants being installed at this time in China, which, in contrast to COOLCEP-S, do produce CO{sub 2} emissions at that. (author)
14. Thermoeconomic analysis of a novel zero-CO{sub 2}-emission high-efficiency power cycle using LNG coldness
Energy Technology Data Exchange (ETDEWEB)
Liu Meng [China National Institute of Standardization, Beijing 100088 (China)], E-mail: liumeng@cnis.gov.cn; Lior, Noam [Department of Mechanical Engineering and Applied Mechanics, University of Pennsylvania, Philadelphia, PA 19104-6315 (United States)], E-mail: lior@seas.upenn.edu; Zhang Na; Han Wei [Institute of Engineering Thermophysics, Chinese Academy of Sciences, P.O. Box 2706, Beijing 100190 (China)
2009-11-15
This paper presents a thermoeconomic analysis aimed at the optimization of a novel zero-CO{sub 2} and other emissions and high-efficiency power and refrigeration cogeneration system, COOLCEP-S (Patent pending), which uses the liquefied natural gas (LNG) coldness during its revaporization. It was predicted that at the turbine inlet temperature (TIT) of 900 deg. C, the energy efficiency of the COOLCEP-S system reaches 59%. The thermoeconomic analysis determines the specific cost, the cost of electricity, the system payback period and the total net revenue. The optimization started by performing a thermodynamic sensitivity analysis, which has shown that for a fixed TIT and pressure ratio, the pinch point temperature difference in the recuperator, {delta}T{sub p1}, and that in the condenser, {delta}T{sub p2} are the most significant unconstrained variables to have a significant effect on the thermal performance of novel cycle. The payback period of this novel cycle (with fixed net power output of 20 MW and plant life of 40 years) was {approx}5.9 years at most, and would be reduced to {approx}3.1 years at most when there is a market for the refrigeration byproduct. The capital investment cost of the economically optimized plant is estimated to be about 1000 $/kWe, and the cost of electricity is estimated to be 0.34-0.37 CNY/kWh ({approx}0.04$/kWh). These values are much lower than those of conventional coal power plants being installed at this time in China, which, in contrast to COOLCEP-S, do produce CO{sub 2} emissions at that.
15. Non-Doped Sky-Blue OLEDs Based on Simple Structured AIE Emitters with High Efficiencies at Low Driven Voltages.
Science.gov (United States)
Islam, Amjad; Zhang, Dongdong; Peng, Ruixiang; Yang, Rongjuan; Hong, Ling; Song, Wei; Wei, Qiang; Duan, Lian; Ge, Ziyi
2017-09-05
Blue organic light-emitting diodes (OLEDs) are necessary for flat-panel display technologies and lighting applications. To make more energy-saving, low-cost and long-lasting OLEDs, efficient materials as well as simple structured devices are in high demand. However, a very limited number of blue OLEDs achieving high stability and color purity have been reported. Herein, three new sky-blue emitters, 1,4,5-triphenyl-2-(4-(1,2,2-triphenylvinyl)phenyl)-1H-imidazole (TPEI), 1-(4-methoxyphenyl)-4,5-diphenyl-2-(4-(1,2,2-triphenylvinyl)phenyl)-1H-imidazole (TPEMeOPhI) and 1-phenyl-2,4,5-tris(4-(1,2,2-triphenylvinyl)phenyl)-1H-imidazole (3TPEI), with a combination of imidazole and tetraphenylethene groups, have been developed. High photoluminescence quantum yields are obtained for these materials. All derivatives have demonstrated aggregation-induced emission (AIE) behavior, excellent thermal stability with high decomposition and glass transition temperatures. Non-doped sky-blue OLEDs with simple structure have been fabricated employing these materials as emitters and realized high efficiencies of 2.41 % (4.92 cd A -1 , 2.70 lm W -1 ), 2.16 (4.33 cd A -1 , 2.59 lm W -1 ) and 3.13 % (6.97 cd A -1 , 4.74 lm W -1 ) for TPEI, TPEMeOPhI and 3TPEI, with small efficiency roll-off. These are among excellent results for molecules constructed from the combination of imidazole and TPE reported so far. The high performance of a 3TPEI-based device shows the promising potential of the combination of imidazole and AIEgen for synthesizing efficient electroluminescent materials for OLED devices. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.
16. Development of a Highly Efficient Hybrid White Organic-Light-Emitting Diode with a Single Emission Layer by Solution Processing.
Science.gov (United States)
Wu, Jun-Yi; Chen, Show-An
2018-02-07
We use a mixed host, 2,6-bis[3-(carbazol-9-yl)phenyl]pyridine blended with 20 wt % tris(4-carbazoyl-9-ylphenyl)amine, to lower the hole-injection barrier, along with the bipolar and high-photoluminescence-quantum-yield (Φ p = 84%), blue thermally activated delay fluorescence (TADF) material of 9,9-dimethyl-9,10-dihydroacridine-2,4,6-triphenyl-1,3,5-triazine (DMAC-TRZ) as a blue dopant to compose the emission layer for the fabrication of a TADF blue organic-light-emitting diode (BOLED). The device is highly efficient with the following performance parameters: maximum brightness (B max ) = 57586 cd/m 2 , maximum current efficiency (CE max ) = 35.3 cd/A, maximum power efficiency (PE max ) = 21.4 lm/W, maximum external quantum efficiency (EQE max ) = 14.1%, and CIE coordinates (0.18, 0.42). This device has the best performance recorded among the reported solution-processed TADF BOLEDs and has a low efficiency roll-off: at brightness values of 1000 and 5000 cd/m 2 , its CEs are close, being 35.1 and 30.1 cd/A, respectively. Upon further doping of the red phosphor Ir(dpm)PQ 2 (emission peak λ max = 595 nm) into the blue emission layer, we obtained a TADF-phosphor hybrid white organic-light-emitting diode (T-P hybrid WOLED) with high performance: B max = 43594 cd/m 2 , CE max = 28.8 cd/A, PE max = 18.1 lm/W, and CIE coordinates (0.38, 0.44). This B max = 43594 cd/m 2 is better than that of the vacuum-deposited WOLED with a blue TADF emitter, 10000 cd/m 2 . This is also the first report on a T-P hybrid WOLED with a solution-processed emitting layer.
17. Thermoeconomic analysis of a novel zero-CO2-emission high-efficiency power cycle using LNG coldness
International Nuclear Information System (INIS)
Liu, Meng; Lior, Noam; Zhang, Na; Han, Wei
2009-01-01
This paper presents a thermoeconomic analysis aimed at the optimization of a novel zero-CO 2 and other emissions and high-efficiency power and refrigeration cogeneration system, COOLCEP-S (Patent pending), which uses the liquefied natural gas (LNG) coldness during its revaporization. It was predicted that at the turbine inlet temperature (TIT) of 900 C, the energy efficiency of the COOLCEP-S system reaches 59%. The thermoeconomic analysis determines the specific cost, the cost of electricity, the system payback period and the total net revenue. The optimization started by performing a thermodynamic sensitivity analysis, which has shown that for a fixed TIT and pressure ratio, the pinch point temperature difference in the recuperator, (delta)T p1 , and that in the condenser, (delta)T p2 are the most significant unconstrained variables to have a significant effect on the thermal performance of novel cycle. The payback period of this novel cycle (with fixed net power output of 20 MW and plant life of 40 years) was ∝5.9 years at most, and would be reduced to ∝3.1 years at most when there is a market for the refrigeration byproduct. The capital investment cost of the economically optimized plant is estimated to be about 1000 /kWe, and the cost of electricity is estimated to be 0.34-0.37 CNY/kWh (∝0.04 USD/kWh). These values are much lower than those of conventional coal power plants being installed at this time in China, which, in contrast to COOLCEP-S, do produce CO 2 emissions at that. (author)
18. High-efficiency, thin-film- and concentrator solar cells from GaAs. Final report; High-efficiency, Duennschicht- und Konzentrator-Solarzellen aus Galliumarsenid. Abschlussbericht
Energy Technology Data Exchange (ETDEWEB)
Wettling, W [Fraunhofer-Institut fuer Solare Energiesysteme (ISE), Freiburg im Breisgau (Germany); Bett, A W [Fraunhofer-Institut fuer Solare Energiesysteme (ISE), Freiburg im Breisgau (Germany); Pilkuhn, M [Stuttgart Univ. (Germany). Physikalisches Teilinstitut 4; Scholz, F [Stuttgart Univ. (Germany). Physikalisches Teilinstitut 4; Baldus, A [Fraunhofer-Institut fuer Solare Energiesysteme (ISE), Freiburg im Breisgau (Germany); Blieske, U [Fraunhofer-Institut fuer Solare Energiesysteme (ISE), Freiburg im Breisgau (Germany); Blug, A [Fraunhofer-Institut fuer Solare Energiesysteme (ISE), Freiburg im Breisgau (Germany); Duong, T [Fraunhofer-Institut fuer Solare Energiesysteme (ISE), Freiburg im Breisgau (Germany); Schetter, C [Fraunhofer-Institut fuer Solare Energiesysteme (ISE), Freiburg im Breisgau (Germany); Stollwerck, G [Fraunhofer-Institut fuer Solare Energiesysteme (ISE), Freiburg im Breisgau (Germany); Sulima, O [Fraunhofer-Institut fuer Solare Energiesysteme (ISE), Freiburg im Breisgau (Germany); Wegener, A [Fraunhofer-Institut fuer Solare Energiesysteme (ISE), Freiburg im Breisgau (Germany); Doernen, A [Stuttgart Univ. (Germany). Physikalisches Teilinstitut 4; Frankowsky, G [Stuttgart Univ. (Germany). Physikalisches Teilinstitut 4; Haase, D [Stuttgart Univ. (Germany). Physikalisches Teilinstitut 4; Hahn, G [Stuttgart Univ. (Germany). Physikalisches Teilinstitut 4; Hangleiter, A [Stuttgart Univ. (Germany). Physikalisches Teilinstitut 4; Stauss, P [Stuttgart Univ. (Germany). Physikalisches Teilinstitut 4; Tsai, C Y [Stuttgart Univ. (Germany). Physikalisches Teilinstitut 4; Zieger, K [Stuttgart Univ. (Germany). Physikalisches Teilinstitut 4
1996-10-01
Main topic of the project was the manufacturing of highly efficient GaAs-solar cells and the fabrication of concentrator cells. During this process significant progress was made with the material preparation, the solar cell technology and the material and process characterisation. This succeeded in the following efficiencies: - GaAs solar cell made by MOVPE technology: 22.9% on 4 cm{sup 2} (AM1.5g) - GaAs solar cell made by LPE-ER process: 22.8% on 4 cm{sup 2} (AM1.5g) - GaAs concentrator solar cell made by LPE-ER process: 24.9% at C=100xAM1.5d - GaAs concentrator module with fresnel lenses: Module efficiency 20.1% (under irradiation of 793 W/m{sup 2}). Another main focus was the epitaxy of GaAs on Si substrate. Two different approaches were investigated. Together with the cooperation partner ASE, Heilbronn a selective growth technology was developed that led to a decreased crack formation. By a simultanous optimization of the other epitaxy and process parameters, the efficiency was increased up to 16.6% AM0 on 1 cm{sup 2} solar cells. Furthermore a hybrid epitaxy was investigated. A GaAs layer was deposited onto a Si substrate using MOVPE. The solar cell structure was grown with a low temperature LPE. Unexpected difficulties appeared with this process, so that fundamental experiments needed to be done with the LPE technology. So far, no solar cells could be manufactured with this method. In addition, work was performed on GaInP solar cells on GaAs substrate. An efficiency of 15.7% (AM0) was acchieved. (orig.) [Deutsch] Gegenstand des Projekts war die Herstellung hocheffizienter GaAs-Solarzellen und die Fertigung von Konzentratorsolarzellen. Dazu wurden wesentliche Fortschritte bei der Materialpraeparation, der Solarzellentechnologie und der Material- and Prozesscharakterisierung erzielt. Diese Erfolge druecken sich in den erzielten Wirkungsgraden aus: - GaAs-Solarzelle hergestellt mit MOVPE-Technologie: 22.9% auf 4 cm{sup 2} (AM1.5g) - GaAs-Solarzelle hergestellt
19. Highly Efficient p-i-n Type Organic Light-emitting Diodes Using ...
African Journals Online (AJOL)
operating voltage of 3.0 V. In addition, impressive characteristics of white .... low voltage drops in the transport layers due to their ... thermal evaporation in high vacuum or organic vapor ... the calibrated silicon photodiode above the OLEDs.
20. Double Compression Expansion Engine: A Parametric Study on a High-Efficiency Engine Concept
KAUST Repository
Bhavani Shankar, Vijai Shankar; Johansson, Bengt; Andersson, Arne
2018-01-01
The Double compression expansion engine (DCEE) concept has exhibited a potential for achieving high brake thermal efficiencies (BTE). The effect of different engine components on system efficiency was evaluated in this work using GT Power
1. A high-efficiency acoustic chamber and the anomalous sample rotation
Science.gov (United States)
Wang, Taylor G.; Allen, J. L.
1992-01-01
A high efficiency acoustic chamber for the levitation and manipulation of liquid or molten samples in a microgravity environment has been developed. The chamber uses two acoustic drivers that are mounted at opposite corners of the chamber; by driving these at the same frequency, with 18-deg phase shifts, an increase in force of a factor of 3-4 is obtainable relative to the force of a single-driver system that is operated at the same power level. This enhancement is due to the increased coupling between the sound driver and the chamber. An anomalous rotation is noted to be associated with the chamber; this is found to be eliminated by a physically as-yet inexplicable empirical solution.
2. Computational design of high efficiency release targets for use at ISOL facilities
CERN Document Server
Liu, Y
1999-01-01
This report describes efforts made at the Oak Ridge National Laboratory to design high-efficiency-release targets that simultaneously incorporate the short diffusion lengths, high permeabilities, controllable temperatures, and heat-removal properties required for the generation of useful radioactive ion beam (RIB) intensities for nuclear physics and astrophysics research using the isotope separation on-line (ISOL) technique. Short diffusion lengths are achieved either by using thin fibrous target materials or by coating thin layers of selected target material onto low-density carbon fibers such as reticulated-vitreous-carbon fiber (RVCF) or carbon-bonded-carbon fiber (CBCF) to form highly permeable composite target matrices. Computational studies that simulate the generation and removal of primary beam deposited heat from target materials have been conducted to optimize the design of target/heat-sink systems for generating RIBs. The results derived from diffusion release-rate simulation studies for selected t...
3. High-efficiency Gas Cogeneration – an Assessment of the Support Mechanism
Directory of Open Access Journals (Sweden)
Maciej Sołtysik
2015-09-01
Full Text Available The development of a single European energy market implies the need to harmonise national laws and the directions of the sector’s growth to EU determinants. One of these elements was the introduction of a system to support the development of high-efficiency cogeneration, including gas cogeneration. Several years of the mechanisms’ performance allows for analysis of the advisability and correctness of the support model format, and assessment of its impact on the sub-sector’s development and the cost of its operation. Against the background of the support system introduction origins, the paper presents results of volumetric and price analyses, trends, and assessment of the balance of property rights and of the mechanism’s effectiveness.
4. Residual stress evaluation by Barkhausen signals with a magnetic field sensor for high efficiency electrical motors
Science.gov (United States)
Tsuchida, Yuji; Enokizono, Masato
2018-04-01
The iron loss of industrial motors increases by residual stress during manufacturing processes. It is very important to make clear the distribution of the residual stress in the motor cores to reduce the iron loss in the motors. Barkhausen signals which occur on electrical steel sheets can be used for the evaluation of the residual stress because they are very sensitive to the material properties. Generally, a B-sensor is used to measure Barkhausen signals, however, we developed a new H-sensor to measure them and applied it into the stress evaluation. It is supposed that the Barkhausen signals by using a H-sensor can be much effective to the residual stress on the electrical steel sheets by referring our results regarding to the stress evaluations. We evaluated the tensile stress of the electrical steel sheets by measuring Barkhausen signals by using our developed H-sensor for high efficiency electrical motors.
5. Data on electrical energy conservation using high efficiency motors for the confidence bounds using statistical techniques.
Science.gov (United States)
Shaikh, Muhammad Mujtaba; Memon, Abdul Jabbar; Hussain, Manzoor
2016-09-01
In this article, we describe details of the data used in the research paper "Confidence bounds for energy conservation in electric motors: An economical solution using statistical techniques" [1]. The data presented in this paper is intended to show benefits of high efficiency electric motors over the standard efficiency motors of similar rating in the industrial sector of Pakistan. We explain how the data was collected and then processed by means of formulas to show cost effectiveness of energy efficient motors in terms of three important parameters: annual energy saving, cost saving and payback periods. This data can be further used to construct confidence bounds for the parameters using statistical techniques as described in [1].
6. Phase I aging assessment of nuclear air-treatment system high efficiency particulate air and adsorbers
International Nuclear Information System (INIS)
Winegardner, W.K.
1996-01-01
A phase I aging assessment of high efficiency particulate air filters and activated carbon gas adsorption units was performed by the Pacific Northwest Laboratory as part of the US Nuclear Regulatory Commission's Nuclear Plant Aging Research Program. Information was compiled concerning design features, failure experience, aging mechanisms, effects, and stressors, and monitoring methods. Over 1100 failures, or 12% of the filter installations, were reported as part of a US Department of energy survey. Investigators from other laboratories have suggested that aging could have contributed to over 80% of these failures. Several instances of impaired performance as the result of the premature aging of carbon were reported. Filter aging mechanisms range from those associated with particle loading to reactions that alter the properties of gaskets. Mechanisms that can lead to impaired adsorber performance include the loss of potentially available active sites as a result of the adsorption of moisture or pollutants. Stressors include heat, moisture, radiation, and airborne particles and contaminants. (orig.)
7. Highly efficient 400 W near-fundamental-mode green thin-disk laser.
Science.gov (United States)
Piehler, Stefan; Dietrich, Tom; Rumpel, Martin; Graf, Thomas; Ahmed, Marwan Abdou
2016-01-01
We report on the efficient generation of continuous-wave, high-brightness green laser radiation. Green lasers are particularly interesting for reliable and reproducible deep-penetration welding of copper or for pumping Ti:Sa oscillators. By intracavity second-harmonic generation in a thin-disk laser resonator designed for fundamental-mode operation, an output power of up to 403 W is demonstrated at a wavelength of 515 nm with almost diffraction-limited beam quality. The unprecedented optical efficiency of 40.7% of green output power with respect to the pump power of the thin-disk laser is enabled by the intracavity use of a highly efficient grating waveguide mirror, which combines the functions of wavelength stabilization and spectral narrowing, as well as polarization selection in a single element.
8. High-Efficiency Dielectric Metasurfaces for Polarization-Dependent Terahertz Wavefront Manipulation
KAUST Repository
Zhang, Huifang
2017-11-30
Recently, metasurfaces made up of dielectric structures have drawn enormous attentions in the optical and infrared regimes due to their high efficiency and designing freedom in manipulating light propagation. Such advantages can also be introduced to terahertz frequencies where efficient functional devices are still lacking. Here, polarization-dependent all-silicon terahertz dielectric metasurfaces are proposed and experimentally demonstrated. The metasurfaces are composed of anisotropic rectangular-shaped silicon pillars on silicon substrate. Each metasurface holds dual different functions depending on the incident polarizations. Furthermore, to suppress the reflection loss and multireflection effect in practical applications, a high-performance polarization-independent antireflection silicon pillar array is also proposed, which can be patterned at the other side of the silicon substrate. Such all-silicon dielectric metasurfaces are easy to fabricate and can be very promising in developing next-generation efficient, compact, and low-cost terahertz functional devices.
9. Investigating the structure preserving encryption of high efficiency video coding (HEVC)
Science.gov (United States)
Shahid, Zafar; Puech, William
2013-02-01
This paper presents a novel method for the real-time protection of new emerging High Efficiency Video Coding (HEVC) standard. Structure preserving selective encryption is being performed in CABAC entropy coding module of HEVC, which is significantly different from CABAC entropy coding of H.264/AVC. In CABAC of HEVC, exponential Golomb coding is replaced by truncated Rice (TR) up to a specific value for binarization of transform coefficients. Selective encryption is performed using AES cipher in cipher feedback mode on a plaintext of binstrings in a context aware manner. The encrypted bitstream has exactly the same bit-rate and is format complaint. Experimental evaluation and security analysis of the proposed algorithm is performed on several benchmark video sequences containing different combinations of motion, texture and objects.
10. High efficiency particulate air filter technology from 1980 to 1985 in the Central Electricity Generating Board
International Nuclear Information System (INIS)
Skledon, R.; Taylor, S.; Fern, C.; Stead, M.
1986-01-01
This paper examines at the Central Electricity Generating Board's methods of High Efficiency Particulate Air (1,700 m 3 /hr) filter testing from conception to the present day. The choice of the test and the early results are looked at followed by the development using new test equipment for checking ladderframe systems. The need for the drawing up of the Central Electricity Generating Board 743401 Standard for filter manufacture and its effect on full implementation is looked into. The advantages and disadvantages of our test procedures are reflected upon and the future developments in test methods and filters for use by the C.E.G.B. in their power stations are discussed. (author)
11. The waffle: a new photovoltaic diode geometry having high efficiency and backside contacts
DEFF Research Database (Denmark)
Leistiko, Otto
1994-01-01
By employing anisotropic etching techniques and advanced device processing it is possible to micromachine new types of mechanical, electronic, and optical devices of silicon, which have unique properties. In this paper the characteristics of a new type of photovoltaic diode fabricated employing...... these processing techniques are described. This novel device has not only high efficiency, but also has both contacts placed on the backside of the cell. The first devices which are only 50 mm in diameter are of relatively good quality with low leakage currents (nA), high breakdown voltages (80 V), and low series...... resistance (mohms). The measured efficiencies at AM 1.5 lie between 12 to 15% with short circuit currents of 25-30 mA/cm2, and open circuit voltages of 0.58-0.6 V...
12. The High-efficiency LED Driver for Visible Light Communication Applications.
Science.gov (United States)
Gong, Cihun-Siyong Alex; Lee, Yu-Chen; Lai, Jyun-Liang; Yu, Chueh-Hao; Huang, Li Ren; Yang, Chia-Yen
2016-08-08
This paper presents a LED driver for VLC. The main purpose is to solve the low data rate problem used to be in switching type LED driver. The GaN power device is proposed to replace the traditional silicon power device of switching LED driver for the purpose of increasing switching frequency of converter, thereby increasing the bandwidth of data transmission. To achieve high efficiency, the diode-connected GaN power transistor is utilized to replace the traditional ultrafast recovery diode used to be in switching type LED driver. This work has been experimentally evaluated on 350-mA output current. The results demonstrate that it supports the data of PWM dimming level encoded in the PPM scheme for VLC application. The experimental results also show that system's efficiency of 80.8% can be achieved at 1-Mb/s data rate.
13. Very High Efficiency Reactor (VHER) Concepts for Electrical Power Generation and Hydrogen Production
International Nuclear Information System (INIS)
PARMA JR, EDWARD J.; PICKARD, PAUL S.; SUO-ANTTILA, AHTI JORMA
2003-01-01
The goal of the Very High Efficiency Reactor study was to develop and analyze concepts for the next generation of nuclear power reactors. The next generation power reactor should be cost effective compared to current power generation plant, passively safe, and proliferation-resistant. High-temperature reactor systems allow higher electrical generating efficiencies and high-temperature process heat applications, such as thermo-chemical hydrogen production. The study focused on three concepts; one using molten salt coolant with a prismatic fuel-element geometry, the other two using high-pressure helium coolant with a prismatic fuel-element geometry and a fuel-pebble element design. Peak operating temperatures, passive-safety, decay heat removal, criticality, burnup, reactivity coefficients, and material issues were analyzed to determine the technical feasibility of each concept
14. High efficiency nanocomposite sorbents for CO2 capture based on amine-functionalized mesoporous capsules
KAUST Repository
Qi, Genggeng; Wang, Yanbing; Estevez, Luis; Duan, Xiaonan; Anako, Nkechi; Park, Ah-Hyung Alissa; Li, Wen; Jones, Christopher W.; Giannelis, Emmanuel P.
2011-01-01
A novel high efficiency nanocomposite sorbent for CO2 capture has been developed based on oligomeric amine (polyethylenimine, PEI, and tetraethylenepentamine, TEPA) functionalized mesoporous silica capsules. The newly synthesized sorbents exhibit extraordinary capture capacity up to 7.9 mmol g-1 under simulated flue gas conditions (pre-humidified 10% CO 2). The CO2 capture kinetics were found to be fast and reached 90% of the total capacities within the first few minutes. The effects of the mesoporous capsule features such as particle size and shell thickness on CO2 capture capacity were investigated. Larger particle size, higher interior void volume and thinner mesoporous shell thickness all improved the CO2 capacity of the sorbents. PEI impregnated sorbents showed good reversibility and stability during cyclic adsorption-regeneration tests (50 cycles). © 2011 The Royal Society of Chemistry.
15. High efficiency and long life of a three-phase power conditioner via interleave control
Directory of Open Access Journals (Sweden)
Kenji Amei
2016-01-01
Full Text Available This study describes the high efficiency and long life of three-phase power conditioners of a photovoltaic (PV system. The current PV system, which is widely spread, has two problems. The first problem is the lifetime of a power conditioner, whereas the other problem is the drop in the efficiency of the conversion because of the characteristics of the solar cell. For those problems, the solar panel and boost chopper circuit were divided into a plurality to configure a power conditioner, and an electrolytic capacitor-less driver with interleave control was realized. The drop in the current generated by the solar cell was suppressed, and an improvement in power generation efficiency was expected. The configuration and principle of a proposed circuit were explained, and results of simulation and experiment were reported.
16. Transition-Metal-Free Highly Efficient Aerobic Oxidation of Sulfides to Sulfoxides under Mild Conditions
Directory of Open Access Journals (Sweden)
Hua Zhang
2009-12-01
Full Text Available A highly efficient transition-metal-free catalytic system Br2/NaNO2/H2O has been developed for a robust and economic acid-free aerobic oxidation of sulfides. It is noteworthy that the sulfide function reacts under mild conditions without over-oxidation to sulfone. The role of NaNO2as an efficient NO equivalent for the activation of molecular oxygen was identified. Under the optimal conditions, a broad range of sulfide substrates were converted into their corresponding sulfoxides in high yields by molecular oxygen. The present catalytic system utilizes cheap and readily available agents as the catalysts, exhibits high selectivity for sulfoxide products and releases only innocuous water as the by-products.
17. RFID Cryptographic Protocol Based on Cyclic Redundancy Check for High Efficiency
Directory of Open Access Journals (Sweden)
Nian Liu
2014-04-01
Full Text Available In this paper, RFID encryption protocol is proposed based on the security problems in wireless signal channel. In order to solve the privacy issues of electronic tags, the most commonly way is to improve algorithms based on Hash function. However, there are some problems that can only play roles in some specific domains. Due to the limitations in various kinds of algorithms, in this paper we put forward a new kind of agreement. When it is required to locate target labels accurately and rapidly in a movement environment, using this agreement can achieve high efficiency through combining the Hash function, the two division search algorithm and CRC check. The results show that this algorithm can accurately identify the tags with merits of low cost, execution rate and anti-attack ability etc.
18. Noise-free high-efficiency photon-number-resolving detectors
International Nuclear Information System (INIS)
Rosenberg, Danna; Lita, Adriana E.; Miller, Aaron J.; Nam, Sae Woo
2005-01-01
High-efficiency optical detectors that can determine the number of photons in a pulse of monochromatic light have applications in a variety of physics studies, including post-selection-based entanglement protocols for linear optics quantum computing and experiments that simultaneously close the detection and communication loopholes of Bell's inequalities. Here we report on our demonstration of fiber-coupled, noise-free, photon-number-resolving transition-edge sensors with 88% efficiency at 1550 nm. The efficiency of these sensors could be made even higher at any wavelength in the visible and near-infrared spectrum without resulting in a higher dark-count rate or degraded photon-number resolution
19. UV and air stability of high-efficiency photoluminescent silicon nanocrystals
Energy Technology Data Exchange (ETDEWEB)
Yang, Jihua, E-mail: yangj@umn.edu [Department of Mechanical Engineering, University of Minnesota, Minneapolis, MN 55455 (United States); Liptak, Richard [Department of Electrical and Computer Engineering, University of Minnesota, Minneapolis, MN 55455 (United States); Department of Physics and Optical Engineering, Rose-Hulman Institute of Technology, 5500 Wabash Ave, Terre Haute, IN 47803 (United States); Rowe, David; Wu, Jeslin [Department of Mechanical Engineering, University of Minnesota, Minneapolis, MN 55455 (United States); Casey, James; Witker, David [Dow Corning Corporation, 2200 W. Salzburg Road, Midland, MI 48686 (United States); Campbell, Stephen A. [Department of Electrical and Computer Engineering, University of Minnesota, Minneapolis, MN 55455 (United States); Kortshagen, Uwe, E-mail: kortshagen@umn.edu [Department of Mechanical Engineering, University of Minnesota, Minneapolis, MN 55455 (United States)
2014-12-30
The effects of UV light and air exposure on the photoluminescent properties of nonthermal plasma-synthesized silicon nanocrystals (Si NCs) were investigated. Si NCs with high-efficiency photoluminescence (PL) have been achieved via a post-synthesis hydrosilylation process. Photobleaching is observed within the first few hours of ultra-violet (UV) irradiation. Equilibrium is reached after ∼4 h of UV exposure wherein the Si NCs are able to retain 52% of the initially measured PL quantum yield (PLQY). UV-treated Si NCs showed recovery of PL with time. Gas-phase passivation of Si NCs by hydrogen afterglow injection improves PLQY and PL stability against UV and air exposure. Additionally, phosphorous doping can also improve UV stability of photoluminescent Si NCs.
20. Highly efficient and enzymatic regioselective undecylenoylation of gastrodin in 2-methyltetrahydrofuran-containing systems.
Directory of Open Access Journals (Sweden)
Rongling Yang
Full Text Available Highly efficient and regioselective acylation of pharmacologically interesting gastrodin with vinyl undecylenic acid has been firstly performed through an enzymatic approach. The highest catalytic activity and regioselectivity towards the acylation of 7'-hydroxyl of gastrodin was obtained with Pseudomonas cepacia lipase. In addition, it was observed the lipase displayed higher activity in the eco-friendly solvent 2-methyltetrahydrofuran-containing systems than in other organic solvents. In the co-solvent mixture of tetrahydrofuran and 2-methyltetrahydrofuran (3/1, v/v, the reaction rate was 60.6 mM/h, substrate conversion exceeded 99%, and 7'-regioselectivity was 93%. It was also interesting that the lipase-catalyzed acylation couldn't be influenced by the benzylic alcohol in gastrodin. However, pseudomonas cepacia lipase displayed different regioselectivity towards gastrodin and arbutin.
1. High efficient ammonia heat pump system for industrial process water using the ISEC concept. Part 1
DEFF Research Database (Denmark)
Rothuizen, Erasmus Damgaard; Madsen, C.; Elmegaard, Brian
2014-01-01
The purpose of the Isolated System Energy Charging (ISEC) is to provide a high-efficient ammonia heat pump system for hot water production. The ISEC concept uses two storage tanks for the water, one discharged and one charged. The charged tank is used for the industrial process while the discharged...... tank, is charging. Charging is done by circulating the water in the tank through the condenser several times and thereby gradually heats the water. This result in a lower condensing temperature than if the water was heated in one step. A dynamic model of the system, implemented in Dymola, is used...... to investigate the performance of the ISEC system. The ISEC concept approaches the efficiency of a number of heat pumps in series and the COP of the system may reach 6.8, which is up to 25 % higher than a conventional heat pump heating water in one step....
2. High efficient ammonia heat pump system for industrial process water using the ISEC concept. Part 2
DEFF Research Database (Denmark)
Olesen, Martin F.; Madsen, Claus; Olsen, Lars
2014-01-01
The Isolated System Energy Charging (ISEC) concept allows for a high efficiency of a heat pump system for hot water production. The ISEC concept consists of two water storage tanks, one charged and one discharged. The charged tank is used for the industrial process, while the discharged tank...... is charging. The charging of the tank is done by recirculating water through the condenser and thereby gradually heating the water. The modelling of the system is described in Part I [1]. In this part, Part II, an experimental test setup of the tank system is reported, the results are presented and further...... modelling of the heat pump and tank system is performed (in continuation of Part I). The modelling is extended to include the system performance with different natural refrigerants and the influence of different types of compressors....
3. New III-V cell design approaches for very high efficiency
Energy Technology Data Exchange (ETDEWEB)
Lundstrom, M.S.; Melloch, M.R.; Lush, G.B.; Patkar, M.P.; Young, M.P. (Purdue Univ., Lafayette, IN (United States))
1993-04-01
This report describes to examine new solar cell desip approaches for achieving very high conversion efficiencies. The program consists of two elements. The first centers on exploring new thin-film approaches specifically designed for M-III semiconductors. Substantial efficiency gains may be possible by employing light trapping techniques to confine the incident photons, as well as the photons emitted by radiative recombination. The thin-film approach is a promising route for achieving substantial performance improvements in the already high-efficiency, single-junction, III-V cell. The second element of the research involves exploring desip approaches for achieving high conversion efficiencies without requiring extremely high-quality material. This work has applications to multiple-junction cells, for which the selection of a component cell often involves a compromise between optimum band pp and optimum material quality. It could also be a benefit manufacturing environment by making the cell's efficiency less dependent on materialquality.
4. A simple and highly efficient Agrobacterium-mediated transformation protocol for Setaria viridis
Directory of Open Access Journals (Sweden)
Polyana Kelly Martins
2015-06-01
Full Text Available The production and use of sugarcane in Brazil is very important for bioenergy production and is recognized as one of the most efficient in the world. In our laboratory, Setaria viridis is being tested as a model plant for sugarcane. S. viridis has biological attributes (rapid life cycle, small genome, diploid, short stature and simple growth requirements that make it suitable for use as a model system. We report a highly efficient protocol for Agrobacterium-mediated genetic transformation of S. viridis. The optimization of several steps in tissue culture allowed the rapid regeneration of plants and increased the rate of transformation up to 29%. This protocol could become a powerful tool for functional genomics in sugarcane.
5. High efficiency transfer of quantum information and multiparticle entanglement generation in translation-invariant quantum chains
International Nuclear Information System (INIS)
Plenio, Martin B; Semiao, Fernando L
2005-01-01
We demonstrate that a translation-invariant chain of interacting quantum systems can be used for high efficiency transfer of quantum entanglement and the generation of multiparticle entanglement over large distances and between arbitrary sites without the requirement of precise spatial or temporal control. The scheme is largely insensitive to disorder and random coupling strengths in the chain. We discuss harmonic oscillator systems both in the case of arbitrary Gaussian states and in situations when at most one excitation is in the system. The latter case, which we prove to be equivalent to an xy-spin chain, may be used to generate genuine multiparticle entanglement. Such a 'quantum data bus' may prove useful in future solid state architectures for quantum information processing
6. Highly efficient full-length hepatitis C virus genotype 1 (strain TN) infectious culture system
DEFF Research Database (Denmark)
Li, Yi-Ping; Ramirez, Santseharay; Jensen, Sanne B
2012-01-01
Chronic infection with hepatitis C virus (HCV) is an important cause of end stage liver disease worldwide. In the United States, most HCV-related disease is associated with genotype 1 infection, which remains difficult to treat. Drug and vaccine development was hampered by inability to culture...... full-length TN infection dose-dependently. Given the unique importance of genotype 1 for pathogenesis, this infectious 1a culture system represents an important advance in HCV research. The approach used and the mutations identified might permit culture development for other HCV isolates, thus......) culture systems in Huh7.5 cells. Here, we developed a highly efficient genotype 1a (strain TN) full-length culture system. We initially found that the LSG substitutions conferred viability to an intergenotypic recombinant composed of TN 5' untranslated region (5'UTR)-NS5A and JFH1 NS5B-3'UTR; recovered...
7. Development of a high-count-rate neutron detector with position sensitivity and high efficiency
International Nuclear Information System (INIS)
Nelson, R.; Sandoval, J.
1996-01-01
While the neutron scattering community is bombarded with hints of new technologies that may deliver detectors with high-count-rate capability, high efficiency, gamma-ray insensitivity, and high resolution across large areas, only the time-tested, gas-filled 3 He and scintillation detectors are in widespread use. Future spallation sources with higher fluxes simply must exploit some of the advanced detector schemes that are as yet unproved as production systems. Technologies indicating promise as neutron detectors include pixel arrays of amorphous silicon, silicon microstrips, microstrips with gas, and new scintillation materials. This project sought to study the competing neutron detector technologies and determine which or what combination will lead to a production detector system well suited for use at a high-intensity neutron scattering source
8. Highly efficient hydrogen storage system based on ammonium bicarbonate/formate redox equilibrium over palladium nanocatalysts.
Science.gov (United States)
Su, Ji; Yang, Lisha; Lu, Mi; Lin, Hongfei
2015-03-01
A highly efficient, reversible hydrogen storage-evolution process has been developed based on the ammonium bicarbonate/formate redox equilibrium over the same carbon-supported palladium nanocatalyst. This heterogeneously catalyzed hydrogen storage system is comparable to the counterpart homogeneous systems and has shown fast reaction kinetics of both the hydrogenation of ammonium bicarbonate and the dehydrogenation of ammonium formate under mild operating conditions. By adjusting temperature and pressure, the extent of hydrogen storage and evolution can be well controlled in the same catalytic system. Moreover, the hydrogen storage system based on aqueous-phase ammonium formate is advantageous owing to its high volumetric energy density. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
9. Field test of radioactive high efficiency filter and filter exchange techniques of fuel cycle examination facility
International Nuclear Information System (INIS)
Hwang, Yong Hwa; Lee, Hyung Kwon; Chun, Young Bum; Park, Dae Gyu; Ahn, Sang Bok; Chu, Yong Sun; Kim, Eun Ka.
1997-12-01
The development of high efficiency filter was started to protect human beings from the contamination of radioactive particles, toxic gases and bacillus, and its gradual performance increment led to the fabrication of Ultra Low Penetration Air Filter (ULPA) today. The application field of ULPA has been spread not only to the air conditioning of nuclear power facilities, semiconductor industries, life science, optics, medical care and general facilities but also to the core of ultra-precision facilities. Periodic performance test on the filters is essential to extend its life-time through effective maintenance. Especially, the bank test on HEPA filter of nuclear facilities handling radioactive materials is required for environmental safety. Nowadays, the bank test technology has been reached to the utilization of a minimized portable detecting instruments and the evaluation techniques can provide high confidence in the area of particle distribution and leakage test efficiency. (author). 16 refs., 13 tabs., 14 figs
10. High-efficiency dielectric barrier Xe discharge lamp: theoretical and experimental investigations
International Nuclear Information System (INIS)
Beleznai, Sz; Mihajlik, G; Agod, A; Maros, I; Juhasz, R; Nemeth, Zs; Jakab, L; Richter, P
2006-01-01
A dielectric barrier Xe discharge lamp producing vacuum-ultraviolet radiation with high efficiency was investigated theoretically and experimentally. The cylindrical glass body of the lamp is equipped with thin strips of metal electrodes applied to diametrically opposite sides of the outer surface. We performed a simulation of discharge plasma properties based on one-dimensional fluid dynamics and also assessed the lamp characteristics experimentally. Simulation and experimental results are analysed and compared in terms of voltage and current characteristics, power input and discharge efficiency. Using the proposed lamp geometry and fast rise-time short square pulses of the driving voltage, an intrinsic discharge efficiency around 56% was predicted by simulation, and more than 60 lm W -1 lamp efficacy (for radiation converted into visible green light by phosphor coating) was demonstrated experimentally
11. High-efficiency supercapacitor electrodes of CVD-grown graphenes hybridized with multiwalled carbon nanotubes
Energy Technology Data Exchange (ETDEWEB)
Kalam, Amir Abul; Bae, Joon Ho [Dept. of Nano-physics, Gachon University, Seongnam (Korea, Republic of); Park, Soo Bin; Seo, Yong Ho [Nanotechnology and Advanced Material Engineering, HMC, and GRI, Sejong University, Seoul (Korea, Republic of)
2015-08-15
We demonstrate, for the first time, high-efficiency supercapacitors by utilizing chemical vapor deposition (CVD)-grown graphenes hybridized with multiwalled carbon nanotubes (CNTs). A single-layer graphene was grown by simple CVD growth method, and transferred to polyethylene terephthalate substrates. The bare graphenes were further hybridized with multiwalled CNTs by drop-coating CNTs on graphenes. The supercapacitors using bare graphenes and graphenes with CNTs revealed that graphenes with CNTs resulted in enhanced supercapacitor performances of 2.2- (the mass-specific capacitance) and 4.4-fold (the area-specific capacitance) of those of bare graphenes. Our strategy to improve electrochemical performance of CVD-grown graphenes is advantageous for large-scale graphene electrodes due to high electrical conductivity of CVD-grown graphenes and cost-effectiveness of using multiwalled CNTs as compared to conventional employment of single-walled CNTs.
12. High-efficiency Gaussian key reconciliation in continuous variable quantum key distribution
Science.gov (United States)
Bai, ZengLiang; Wang, XuYang; Yang, ShenShen; Li, YongMin
2016-01-01
Efficient reconciliation is a crucial step in continuous variable quantum key distribution. The progressive-edge-growth (PEG) algorithm is an efficient method to construct relatively short block length low-density parity-check (LDPC) codes. The qua-sicyclic construction method can extend short block length codes and further eliminate the shortest cycle. In this paper, by combining the PEG algorithm and qua-si-cyclic construction method, we design long block length irregular LDPC codes with high error-correcting capacity. Based on these LDPC codes, we achieve high-efficiency Gaussian key reconciliation with slice recon-ciliation based on multilevel coding/multistage decoding with an efficiency of 93.7%.
13. Novel Low Cost Organic Vapor Jet Printing of Striped High Efficiency Phosphorescent OLEDs for White Lighting
Energy Technology Data Exchange (ETDEWEB)
Mike Hack
2008-12-31
In this program, Universal Display Corporation and University of Michigan proposed to integrate three innovative concepts to meet the DOE's Solid State Lighting (SSL) goals: (1) high-efficiency phosphorescent organic light emitting device (PHOLED{trademark}) technology, (2) a white lighting design that is based on a series of red, green and blue OLED stripes, and (3) the use of a novel cost-effective, high rate, mask-less deposition process called organic vapor jet printing (OVJP). Our PHOLED technology offers up to four-times higher power efficiency than other OLED approaches for general lighting. We believe that one of the most promising approaches to maximizing the efficiency of OLED lighting sources is to produce stripes of the three primary colors at such a pitch (200-500 {mu}m) that they appear as a uniform white light to an observer greater than 1 meter (m) away from the illumination source. Earlier work from a SBIR Phase 1 entitled 'White Illumination Sources Using Striped Phosphorescent OLEDs' suggests that stripe widths of less than 500 {mu}m appear uniform from a distance of 1m without the need for an external diffuser. In this program, we intend to combine continued advances in this PHOLED technology with the striped RGB lighting design to demonstrate a high-efficiency, white lighting source. Using this background technology, the team has focused on developing and demonstrating the novel cost-effective OVJP process to fabricate these high-efficiency white PHOLED light sources. Because this groundbreaking OVJP process is a direct printing approach that enables the OLED stripes to be printed without a shadow mask, OVJP offers very high material utilization and high throughput without the costs and wastage associated with a shadow mask (i.e. the waste of material that deposits on the shadow mask itself). As a direct printing technique, OVJP also has the potential to offer ultra-high deposition rates (> 1,000 Angstroms/second) for any size or
14. High-efficiency genome editing and allele replacement in prototrophic and wild strains of Saccharomyces.
Science.gov (United States)
Alexander, William G; Doering, Drew T; Hittinger, Chris Todd
2014-11-01
Current genome editing techniques available for Saccharomyces yeast species rely on auxotrophic markers, limiting their use in wild and industrial strains and species. Taking advantage of the ancient loss of thymidine kinase in the fungal kingdom, we have developed the herpes simplex virus thymidine kinase gene as a selectable and counterselectable marker that forms the core of novel genome engineering tools called the H: aploid E: ngineering and R: eplacement P: rotocol (HERP) cassettes. Here we show that these cassettes allow a researcher to rapidly generate heterogeneous populations of cells with thousands of independent chromosomal allele replacements using mixed PCR products. We further show that the high efficiency of this approach enables the simultaneous replacement of both alleles in diploid cells. Using these new techniques, many of the most powerful yeast genetic manipulation strategies are now available in wild, industrial, and other prototrophic strains from across the diverse Saccharomyces genus. Copyright © 2014 by the Genetics Society of America.
15. Crystal growth for high-efficiency silicon solar cells workshop: Summary
Science.gov (United States)
Dumas, K. A.
1985-01-01
The state of the art in the growth of silicon crystals for high-efficiency solar cells are reviewed, sheet requirements are defined, and furture areas of research are identified. Silicon sheet material characteristics that limit cell efficiencies and yields were described as well as the criteria for the ideal sheet-growth method. The device engineers wish list to the material engineer included: silicon sheet with long minority carrier lifetime that is uniform throughout the sheet, and which doesn't change during processing; and sheet material that stays flat throughout device processing, has uniform good mechanical strength, and is low cost. Impurities in silicon solar cells depreciate cell performance by reducing diffusion length and degrading junctions. The impurity behavior, degradation mechanisms, and variations in degradation threshold with diffusion length for silicon solar cells were described.
16. Ultracompact high-efficiency polarising beam splitter based on silicon nanobrick arrays.
Science.gov (United States)
Zheng, Guoxing; Liu, Guogen; Kenney, Mitchell Guy; Li, Zile; He, Ping'an; Li, Song; Ren, Zhi; Deng, Qiling
2016-03-21
Since the transmission of anisotropic nano-structures is sensitive to the polarisation of an incident beam, a novel polarising beam splitter (PBS) based on silicon nanobrick arrays is proposed. With careful design of such structures, an incident beam with polarisation direction aligned with the long axis of the nanobrick is almost totally reflected (~98.5%), whilst that along the short axis is nearly totally transmitted (~94.3%). More importantly, by simply changing the width of the nanobrick we can shift the peak response wavelength from 1460 nm to 1625 nm, covering S, C and L bands of the fiber telecommunications windows. The silicon nanobrick-based PBS can find applications in many fields which require ultracompactness, high efficiency, and compatibility with semiconductor industry technologies.
17. High-Order Dielectric Metasurfaces for High-Efficiency Polarization Beam Splitters and Optical Vortex Generators
Science.gov (United States)
Guo, Zhongyi; Zhu, Lie; Guo, Kai; Shen, Fei; Yin, Zhiping
2017-08-01
In this paper, a high-order dielectric metasurface based on silicon nanobrick array is proposed and investigated. By controlling the length and width of the nanobricks, the metasurfaces could supply two different incremental transmission phases for the X-linear-polarized (XLP) and Y-linear-polarized (YLP) light with extremely high efficiency over 88%. Based on the designed metasurface, two polarization beam splitters working in high-order diffraction modes have been designed successfully, which demonstrated a high transmitted efficiency. In addition, we have also designed two vortex-beam generators working in high-order diffraction modes to create vortex beams with the topological charges of 2 and 3. The employment of dielectric metasurfaces operating in high-order diffraction modes could pave the way for a variety of new ultra-efficient optical devices.
18. High-efficiency terahertz polarization devices based on the dielectric metasurface
Science.gov (United States)
Zhou, Jian; Wang, JingJing; Guo, Kai; Shen, Fei; Zhou, Qingfeng; Zhiping yin; Guo, Zhongyi
2018-02-01
Metasurfaces are composed of the subwavelength structures, which can be used to manipulate the amplitude, phase, and polarization of incident electromagnetic waves efficiently. Here, we propose a novel type of dielectric metasurface based on crystal Si for realizing to manipulate the terahertz wave, in which by varying the geometric sizes of the Si micro-bricks, the transmitting phase of the terahertz wave can almost span over the entire 2π range for both of the x-polarization and y-polarization simultaneously, while keeping the similarly high-transmission amplitudes (over 90%). At the frequency of 1.0 THz, we have successfully designed a series of controllable THz devices, such as the polarization-dependent beam splitter, polarization-independent beam deflector and the focusing lenses based on the designed metasurfaces. Our designs are easy to fabricate and can be promising in developing high-efficiency THz functional devices.
19. Editors' Choice Growth of Layered WS2Electrocatalysts for Highly Efficient Hydrogen Production Reaction
KAUST Repository
Alsabban, Merfat M.
2016-08-18
Seeking more economical alternative electrocatalysts without sacrificing much in performance to replace precious metal Pt is one of the major research topics in hydrogen evolution reactions (HER). Tungsten disulfide (WS2) has been recognized as a promising substitute for Pt owing to its high efficiency and low-cost. Since most existing works adopt solution-synthesized WS2 crystallites for HER, direct growth of WS2 layered materials on conducting substrates should offer new opportunities. The growth of WS2 by the thermolysis of ammonium tetrathiotungstate (NH4)(2)WS4 was examined under various gaseous environments. Structural analysis and electrochemical studies show that the H2S environment leads to the WS2 catalysts with superior HER performance with an extremely low overpotential (eta(10) = 184 mV). (C) The Author(s) 2016. Published by ECS. All rights reserved.
20. Volume Bragg grating narrowed high-power and highly efficient cladding-pumped Raman fiber laser.
Science.gov (United States)
Liu, Jun; Yao, Weichao; Zhao, Chujun; Shen, Deyuan; Fan, Dianyuan
2014-12-10
High-power and highly efficient operation of a single-mode cladding-pumped Raman fiber laser with narrow lasing bandwidth is demonstrated. The spectral narrowing was realized by an external cavity containing a volume Bragg grating with a center wavelength of 1658 nm. A maximum output power of 10.4 W at 1658.3 nm with a spectral linewidth (FWHM) of ∼0.1 nm was obtained for the launched pump power of 18.4 W, corresponding to a slope efficiency of 109% with respect to the launched pump power. Lasing characteristics of free-running operation are also evaluated and discussed.
1. High-efficient extraction of principal medicinal components from fresh Phellodendron bark (cortex phellodendri
Directory of Open Access Journals (Sweden)
Keqin Xu
2018-05-01
Full Text Available There are three key medicinal components (phellodendrine, berberine and palmatine in the extracts of Phellodendron bark, as one of the fundamental herbs of traditional Chinese medicine. Different extraction methods and solvent combinations were investigated to obtain the optimal technologies for high-efficient extraction of these medicinal components. Results: The results showed that combined solvents have higher extracting effect of phellodendrine, berberine and palmatine than single solvent, and the effect of ultrasonic extraction is distinctly better than those of distillation and soxhlet extraction. Conclusion: The hydrochloric acid/methanol-ultrasonic extraction has the best effect for three medicinal components of fresh Phellodendron bark, providing an extraction yield of 103.12 mg/g berberine, 24.41 mg/g phellodendrine, 1.25 mg/g palmatine. Keywords: Phellodendron, Cortex phellodendri, Extraction methods, Medicinal components
2. High-efficient extraction of principal medicinal components from fresh Phellodendron bark (cortex phellodendri).
Science.gov (United States)
Xu, Keqin; He, Gongxiu; Qin, Jieming; Cheng, Xuexiang; He, Hanjie; Zhang, Dangquan; Peng, Wanxi
2018-05-01
There are three key medicinal components (phellodendrine, berberine and palmatine) in the extracts of Phellodendron bark, as one of the fundamental herbs of traditional Chinese medicine. Different extraction methods and solvent combinations were investigated to obtain the optimal technologies for high-efficient extraction of these medicinal components. The results showed that combined solvents have higher extracting effect of phellodendrine, berberine and palmatine than single solvent, and the effect of ultrasonic extraction is distinctly better than those of distillation and soxhlet extraction. The hydrochloric acid/methanol-ultrasonic extraction has the best effect for three medicinal components of fresh Phellodendron bark, providing an extraction yield of 103.12 mg/g berberine, 24.41 mg/g phellodendrine, 1.25 mg/g palmatine.
3. Highly efficient and enzymatic regioselective undecylenoylation of gastrodin in 2-methyltetrahydrofuran-containing systems.
Science.gov (United States)
Yang, Rongling; Liu, Xueming; Chen, Zhiyi; Yang, Chunying; Lin, Yaosheng; Wang, Siyuan
2014-01-01
Highly efficient and regioselective acylation of pharmacologically interesting gastrodin with vinyl undecylenic acid has been firstly performed through an enzymatic approach. The highest catalytic activity and regioselectivity towards the acylation of 7'-hydroxyl of gastrodin was obtained with Pseudomonas cepacia lipase. In addition, it was observed the lipase displayed higher activity in the eco-friendly solvent 2-methyltetrahydrofuran-containing systems than in other organic solvents. In the co-solvent mixture of tetrahydrofuran and 2-methyltetrahydrofuran (3/1, v/v), the reaction rate was 60.6 mM/h, substrate conversion exceeded 99%, and 7'-regioselectivity was 93%. It was also interesting that the lipase-catalyzed acylation couldn't be influenced by the benzylic alcohol in gastrodin. However, pseudomonas cepacia lipase displayed different regioselectivity towards gastrodin and arbutin.
4. High-efficiency photorealistic computer-generated holograms based on the backward ray-tracing technique
Science.gov (United States)
Wang, Yuan; Chen, Zhidong; Sang, Xinzhu; Li, Hui; Zhao, Linmin
2018-03-01
Holographic displays can provide the complete optical wave field of a three-dimensional (3D) scene, including the depth perception. However, it often takes a long computation time to produce traditional computer-generated holograms (CGHs) without more complex and photorealistic rendering. The backward ray-tracing technique is able to render photorealistic high-quality images, which noticeably reduce the computation time achieved from the high-degree parallelism. Here, a high-efficiency photorealistic computer-generated hologram method is presented based on the ray-tracing technique. Rays are parallelly launched and traced under different illuminations and circumstances. Experimental results demonstrate the effectiveness of the proposed method. Compared with the traditional point cloud CGH, the computation time is decreased to 24 s to reconstruct a 3D object of 100 ×100 rays with continuous depth change.
5. Development of functional nano-particle layer for highly efficient OLED
Science.gov (United States)
Lee, Jae-Hyun; Kim, Min-Hoi; Choi, Haechul; Choi, Yoonseuk
2015-12-01
Organic light emitting diodes (OLEDs) are now widely commercialized in market due to many advantages such as possibility of making thin or flexible devices. Nevertheless there are still several things to obtain the high quality flexible OLEDs, one of the most important issues is the light extraction of the device. It is known that OLEDs have the typical light loss such as the waveguide loss, plasmon absorption loss and internal total reflection. In this paper, we demonstrate the one-step processed light scattering films with aluminum oxide nano-particles and polystyrene matrix composite to achieve highly efficient OLEDs. Optical characteristics and surface roughness of light scattering film was optimized by changing the mixing concentration of Al2O3 nano-particles and investigated with the atomic force microscopy and hazemeter, respectively.
6. Segmentation of low‐cost high efficiency oxide‐based thermoelectric materials
DEFF Research Database (Denmark)
Le, Thanh Hung; Van Nong, Ngo; Linderoth, Søren
2015-01-01
Thermoelectric (TE) oxide materials have attracted great interest in advanced renewable energy research owing to the fact that they consist of abundant elements, can be manufactured by low-cost processing, sustain high temperatures, be robust and provide long lifetime. However, the low conversion...... efficiency of TE oxides has been a major drawback limiting these materials to broaden applications. In this work, theoretical calculations are used to predict how segmentation of oxide and semimetal materials, utilizing the benefits of both types of materials, can provide high efficiency, high temperature...... oxide-based segmented legs. The materials for segmentation are selected by their compatibility factors and their conversion efficiency versus material cost, i.e., “efficiency ratio”. Numerical modelling results showed that conversion efficiency could reach values of more than 10% for unicouples using...
7. Editors' Choice Growth of Layered WS2Electrocatalysts for Highly Efficient Hydrogen Production Reaction
KAUST Repository
Alsabban, Merfat M.; Min, Shixiong; Hedhili, Mohamed N.; Ming, Jun; Li, Lain-Jong; Huang, Kuo-Wei
2016-01-01
Seeking more economical alternative electrocatalysts without sacrificing much in performance to replace precious metal Pt is one of the major research topics in hydrogen evolution reactions (HER). Tungsten disulfide (WS2) has been recognized as a promising substitute for Pt owing to its high efficiency and low-cost. Since most existing works adopt solution-synthesized WS2 crystallites for HER, direct growth of WS2 layered materials on conducting substrates should offer new opportunities. The growth of WS2 by the thermolysis of ammonium tetrathiotungstate (NH4)(2)WS4 was examined under various gaseous environments. Structural analysis and electrochemical studies show that the H2S environment leads to the WS2 catalysts with superior HER performance with an extremely low overpotential (eta(10) = 184 mV). (C) The Author(s) 2016. Published by ECS. All rights reserved.
8. Presence of a highly efficient binding to bacterial contamination can distort data from binding studies
International Nuclear Information System (INIS)
Balcar, V.J.
1990-01-01
3 HGABA at low concentrations (5-10 nM) was bound by what appeared to be a GABA receptor binding site in bacterial contamination originating from a batch of distilled water. Under experimental conditions similar to those usually employed in 3 HGABA binding studies, the apparent binding displayed a very high specific component and a high efficiency in terms of 3 HGABA bound per mg of protein. The binding was blocked by muscimol but not by isoguvacine, SR95531 and nipecotic acid. These characteristics suggest that the presence of such spurious binding in the experiments using 3H-labeled ligands in brain homogenates may not always be very obvious and, moreover, it can result in subtle, but serious, distortions of data from such studies, which may not be immediately recognized
9. Enhanced conductive loss in nickel–cobalt sulfide nanostructures for highly efficient microwave absorption and shielding
Science.gov (United States)
Li, Wanrong; Zhou, Min; Lu, Fei; Liu, Hongfei; Zhou, Yuxue; Zhu, Jun; Zeng, Xianghua
2018-06-01
Microwave-absorbing materials with light weight and high efficiency are desirable in addressing electromagnetic interference (EMI) problems. Herein, a nickel–cobalt sulfide (NCS) nanostructure was employed as a robust microwave absorber, which displayed an optimized reflection loss of ‑49.1 dB in the gigahertz range with a loading of only 20 wt% in an NCS/paraffin wax composite. High electrical conductivity was found to contribute prominent conductive loss in NCS, leading to intense dielectric loss within a relatively low mass loading. Furthermore, owing to its high electrical conductivity and remarkable dielectric loss to microwaves, the prepared NCS exhibited excellent performance in EMI shielding. The EMI shielding efficiency of the 50 wt% NCS/paraffin composite exceeded 55 dB at the X-band, demonstrating NCS is a versatile candidate for solving EMI problems.
10. Trial of accelerator cells machining with high precision and high efficiency at Okayama region
International Nuclear Information System (INIS)
Yoshikawa, Mitsuo; Yoden, Hiroyuki; Yokomizo, Seiichi; Sumida, Tsuneto; Kunishida, Jun; Oshita, Isao
2005-01-01
In the framework of the project 'Promotion of Science and Technology in Regional Areas' by the Ministry of Education, Culture, Sports, Science and Technology, we have prepared a special apparatus for machining accelerator cells with a high precision and a high efficiency for the future linear collider. A machining with as small an error as 2 micrometers has been realized. Necessary time to finish one accelerator cell is reduced from 128 minutes to 34 minutes due to the suppression of the heating of the object at the machining. If newly developed one chuck method was employed, the precision and efficiency would be further improved. By cutting at both sides of the spindle, the necessary time for machining would be reduced by half. (author)
11. Environmental friendly high efficient light source. Plasma lamp. 2006 annual report
Energy Technology Data Exchange (ETDEWEB)
Courret, G.
2006-07-01
This annual report for 2006 for the Swiss Federal Office of Energy (SFOE) reports on work being done on the development of a high-efficiency source of light based on the light emission of a plasma. The report presents a review of work done in 2006, including thermodynamics and assessment of the efficiency of the magnetron, tests with small bulbs, study of the standing wave ratio (microwave fluxes) and the development of a new coupling system to allow ignition in very small bulbs. Also, knowledge on the fillings of the bulb and induced effects of the modulator were gained. The development of a second generation of modulator to obtain higher efficiency at lower power is noted.
12. Sliver Solar Cells: High-Efficiency, Low-Cost PV Technology
Directory of Open Access Journals (Sweden)
Evan Franklin
2007-01-01
Full Text Available Sliver cells are thin, single-crystal silicon solar cells fabricated using standard fabrication technology. Sliver modules, composed of several thousand individual Sliver cells, can be efficient, low-cost, bifacial, transparent, flexible, shadow tolerant, and lightweight. Compared with current PV technology, mature Sliver technology will need 10% of the pure silicon and fewer than 5% of the wafer starts per MW of factory output. This paper deals with two distinct challenges related to Sliver cell and Sliver module production: providing a mature and robust Sliver cell fabrication method which produces a high yield of highly efficient Sliver cells, and which is suitable for transfer to industry; and, handling, electrically interconnecting, and encapsulating billions of sliver cells at low cost. Sliver cells with efficiencies of 20% have been fabricated at ANU using a reliable, optimised processing sequence, while low-cost encapsulation methods have been demonstrated using a submodule technique.
13. Realization of highly efficient polymer solar cell based on PBDTTT-EFT and [71]PCBM
Science.gov (United States)
Bharti, Vishal; Chand, Suresh; Dutta, Viresh
2018-04-01
In this work, we have fabricated highly efficient polymer solar cells based on the blend of PBDTTT-EFT:PC71BM in the inverted device configuration. By using low temperature processed zinc oxide (ZnO) nanoparticles as an electron-transport layer (ETL) and 1,8-diiodooctane (DIO) as additive in chlorobenzene (CB) solvent we have achieved PCE of 9.43% with an excellent short-circuit current density (Jsc) of 17.6 mAcm-2, open circuit voltage (Voc) of 0.80 V and fill factor (FF) of 0.67. These results reveals that addition of 3% DIO additive in CB solvent improve the morphology (lower charge carrier recombination and better metal/organic semiconductor interface) and provide uniform interpenetrating networks in PBDTTT-EFT:PC71BM blend active layer.
14. High-efficiency supercapacitor electrodes of CVD-grown graphenes hybridized with multiwalled carbon nanotubes
International Nuclear Information System (INIS)
Kalam, Amir Abul; Bae, Joon Ho; Park, Soo Bin; Seo, Yong Ho
2015-01-01
We demonstrate, for the first time, high-efficiency supercapacitors by utilizing chemical vapor deposition (CVD)-grown graphenes hybridized with multiwalled carbon nanotubes (CNTs). A single-layer graphene was grown by simple CVD growth method, and transferred to polyethylene terephthalate substrates. The bare graphenes were further hybridized with multiwalled CNTs by drop-coating CNTs on graphenes. The supercapacitors using bare graphenes and graphenes with CNTs revealed that graphenes with CNTs resulted in enhanced supercapacitor performances of 2.2- (the mass-specific capacitance) and 4.4-fold (the area-specific capacitance) of those of bare graphenes. Our strategy to improve electrochemical performance of CVD-grown graphenes is advantageous for large-scale graphene electrodes due to high electrical conductivity of CVD-grown graphenes and cost-effectiveness of using multiwalled CNTs as compared to conventional employment of single-walled CNTs
15. Toward high-efficiency and detailed Monte Carlo simulation study of the granular flow spallation target
Science.gov (United States)
Cai, Han-Jie; Zhang, Zhi-Lei; Fu, Fen; Li, Jian-Yang; Zhang, Xun-Chao; Zhang, Ya-Ling; Yan, Xue-Song; Lin, Ping; Xv, Jian-Ya; Yang, Lei
2018-02-01
The dense granular flow spallation target is a new target concept chosen for the Accelerator-Driven Subcritical (ADS) project in China. For the R&D of this kind of target concept, a dedicated Monte Carlo (MC) program named GMT was developed to perform the simulation study of the beam-target interaction. Owing to the complexities of the target geometry, the computational cost of the MC simulation of particle tracks is highly expensive. Thus, improvement of computational efficiency will be essential for the detailed MC simulation studies of the dense granular target. Here we present the special design of the GMT program and its high efficiency performance. In addition, the speedup potential of the GPU-accelerated spallation models is discussed.
16. High-efficient full-duplex WDM-RoF system with sub-central station
Science.gov (United States)
Liu, Anliang; Yin, Hongxi; Wu, Bin
2018-05-01
With an additional sub-central station (S-CS), a high-efficient full-duplex radio-over-fiber (RoF) system compatible with the wavelength-division-multiplexing technology is proposed and experimentally demonstrated in this paper. To improve the dispersion tolerance of the RoF system, the baseband data format for the downlink and an all-optical down-conversion approach for the uplink are employed. In addition, this RoF system can not only make full use of the fiber link resources but also realize the upstream transmission without any local light sources at remote base stations (BSs). A 10-GHz RoF experimental system with a 1.25-Gb/s rate bidirectional transmission is established based on the S-CS structure. The feasibility and reliability of this RoF system are verified through eye diagrams and bit error rate (BER) curves experimentally obtained.
17. High efficiency grating couplers based on shared process with CMOS MOSFETs
International Nuclear Information System (INIS)
Qiu Chao; Sheng Zhen; Wu Ai-Min; Wang Xi; Zou Shi-Chang; Gan Fu-Wan; Li Le; Albert Pang
2013-01-01
Grating couplers are widely investigated as coupling interfaces between silicon-on-insulator waveguides and optical fibers. In this work, a high-efficiency and complementary metal—oxide—semiconductor (CMOS) process compatible grating coupler is proposed. The poly-Si layer used as a gate in the CMOS metal—oxide—semiconductor field effect transistor (MOSFET) is combined with a normal fully etched grating coupler, which greatly enhances its coupling efficiency. With optimal structure parameters, a coupling efficiency can reach as high as ∼ 70% at a wavelength of 1550 nm as indicated by simulation. From the angle of fabrication, all masks and etching steps are shared between MOSFETs and grating couplers, thereby making the high performance grating couplers easily integrated with CMOS circuits. Fabrication errors such as alignment shift are also simulated, showing that the device is quite tolerant in fabrication. (electromagnetism, optics, acoustics, heat transfer, classical mechanics, and fluid dynamics)
18. High-efficiency THz modulator based on phthalocyanine-compound organic films
International Nuclear Information System (INIS)
He, Ting; Zhang, Bo; Shen, Jingling; Zang, Mengdi; Chen, Tianji; Hu, Yufeng; Hou, Yanbing
2015-01-01
We report a high efficiency, broadband terahertz (THz) modulator following a study of phthalocyanine-compound organic films irradiated with an external excitation laser. Both transmission and reflection modulations of each organic/silicon bilayers were measured using THz time-domain and continuous-wave systems. For very low intensities, the experimental results show that AlClPc/Si can achieve a high modulation factor for transmission and reflection, indicating that AlClPc/Si has a superior modulation efficiency compared with the other films (CuPc and SnCl 2 Pc). In contrast, the strong attenuation of the transmitted and reflected THz waves revealed that a nonlinear absorption process takes place at the organic/silicon interface
19. Highly Efficient TADF Polymer Electroluminescence with Reduced Efficiency Roll-off via Interfacial Exciplex Host Strategy.
Science.gov (United States)
Lin, Xingdong; Zhu, Yunhui; Zhang, Baohua; Zhao, Xiaofei; Yao, Bing; Cheng, Yanxiang; Li, Zhanguo; Qu, Yi; Xie, Zhiyuan
2018-01-10
Solution-processed organic light-emitting diodes (s-OLED) consisting of TAPC/TmPyPB interfacial exciplex host and polymer PAPTC TADF emitter are prepared, simultaneously displaying ultralow voltages (2.50/2.91/3.51/4.91 V at luminance of 1/100/1000/1000 cd m -2 ), high efficiencies (14.9%, 50.1 lm W -1 ), and extremely low roll-off rates (J 50 of 63.16 mA cm -2 , L 50 of ca. 15000 cd m -2 ). Such performance is distinctly higher than that of pure-PAPTC s-OLED. Compared to pure-PAPTC, the advanced emissive layer structure of TAPC:PAPTC/TmPyPB is unique in much higher PL quantum yield (79.5 vs 36.3%) and nearly 4-fold enhancement in k RISC of the PAPTC emitter to 1.48 × 10 7 s -1 .
20. PCR-Based Seamless Genome Editing with High Efficiency and Fidelity in Escherichia coli
DEFF Research Database (Denmark)
Liu, Yilan; Yang, Maohua; Yan, Daojiang
2016-01-01
Efficiency and fidelity are the key obstacles for genome editing toolboxes. In the present study, a PCR-based tandem repeat assisted genome editing (TRAGE) method with high efficiency and fidelity was developed. The design of TRAGE is based on the mechanism of repair of spontaneous double...... for seamlessly deleting, substituting and inserting targeted genes using PCR products. The effects of different manipulations including sucrose addition time, subculture times in LB with sucrose and stages of inoculation on the efficiency were investigated. With our recommended procedure, seamless excision...... of cat-sacB cassette can be realized in 48 h efficiently. We believe that the developed method has great potential for seamless genome editing in E. coli....
1. High-efficiency frequency doubling of continuous-wave laser light.
Science.gov (United States)
Ast, Stefan; Nia, Ramon Moghadas; Schönbeck, Axel; Lastzka, Nico; Steinlechner, Jessica; Eberle, Tobias; Mehmet, Moritz; Steinlechner, Sebastian; Schnabel, Roman
2011-09-01
We report on the observation of high-efficiency frequency doubling of 1550 nm continuous-wave laser light in a nonlinear cavity containing a periodically poled potassium titanyl phosphate crystal (PPKTP). The fundamental field had a power of 1.10 W and was converted into 1.05 W at 775 nm, yielding a total external conversion efficiency of 95±1%. The latter value is based on the measured depletion of the fundamental field being consistent with the absolute values derived from numerical simulations. According to our model, the conversion efficiency achieved was limited by the nonperfect mode matching into the nonlinear cavity and by the nonperfect impedance matching for the maximum input power available. Our result shows that cavity-assisted frequency conversion based on PPKTP is well suited for low-decoherence frequency conversion of quantum states of light.
2. High efficiency, monolithic fiber chirped pulse amplification system for high energy femtosecond pulse generation.
Science.gov (United States)
Peng, Xiang; Kim, Kyungbum; Mielke, Michael; Jennings, Stephen; Masor, Gordon; Stohl, Dave; Chavez-Pirson, Arturo; Nguyen, Dan T; Rhonehouse, Dan; Zong, Jie; Churin, Dmitriy; Peyghambarian, N
2013-10-21
A novel monolithic fiber-optic chirped pulse amplification (CPA) system for high energy, femtosecond pulse generation is proposed and experimentally demonstrated. By employing a high gain amplifier comprising merely 20 cm of high efficiency media (HEM) gain fiber, an optimal balance of output pulse energy, optical efficiency, and B-integral is achieved. The HEM amplifier is fabricated from erbium-doped phosphate glass fiber and yields gain of 1.443 dB/cm with slope efficiency >45%. We experimentally demonstrate near diffraction-limited beam quality and near transform-limited femtosecond pulse quality at 1.55 µm wavelength. With pulse energy >100 µJ and pulse duration of 636 fs (FWHM), the peak power is estimated to be ~160 MW. NAVAIR Public Release Distribution Statement A-"Approved for Public release; distribution is unlimited".
3. Flexible Superhydrophobic and Superoleophilic MoS2 Sponge for Highly Efficient Oil-Water Separation
Science.gov (United States)
Gao, Xiaojia; Wang, Xiufeng; Ouyang, Xiaoping; Wen, Cuie
2016-01-01
Removal of oils and organic solvents from water is an important global challenge for energy conservation and environmental protection. Advanced sorbent materials with excellent sorption capacity need to be developed. Here we report on a superhydrophobic and superoleophilic MoS2 nanosheet sponge (SMS) for highly efficient separation and absorption of oils or organic solvents from water. This novel sponge exhibits excellent absorption performance through a combination of superhydrophobicity, high porosity, robust stability in harsh conditions (including flame retardance and inertness to corrosive and different temperature environments) and excellent mechanical properties. The dip-coating strategy proposed for the fabrication of the SMS, which does not require a complicated process or sophisticated equipment, is very straightforward and easy to scale up. This finding shows promise for water remediation and oil recovery. PMID:27272562
4. Mixed-ligand Al complex—a new approach for more high efficient OLEDs
International Nuclear Information System (INIS)
Petrova, Petia K.; Tomova, Reni L.; Stoycheva-Topalova, Rumiana T.; Kaloyanova, Stefka S.; Deligeorgiev, Todor G.
2012-01-01
The mixed-ligand Aluminum bis(8-hydroxyquinoline) acetylacetonate (Alq 2 Acac) complex was presented and its performance as electroluminescent and electron transporting layer for OLED was studied. The photophysical properties of the novel complex were investigated and compared with the properties of the parent Alq 3 . Highly efficient OLED based on the mixed-ligand Al complex was developed with two times higher luminescence and efficiency compared to the identical OLED based on the conventional Alq 3 The better performance of the devices make the novel Al complex a very promising material for OLEDs. - Highlights: ► A novel electroluminescent Alq 2 Acac complex is presented as material for OLED. ► Electroluminescent emission of Alq 2 Acac is very similar to that of commercial Alq 3 . ► Devices with Alq 2 Acac show better characteristics compared to those with Alq 3 .
5. Design of a high efficiency 30 kW boost composite converter
Energy Technology Data Exchange (ETDEWEB)
Kim, Hyeokjin [Univ. of Colorado, Boulder, CO (United States); Chen, Hua [Univ. of Colorado, Boulder, CO (United States); Maksimovic, Dragan [Univ. of Colorado, Boulder, CO (United States); Erickson, Robert W. [Univ. of Colorado, Boulder, CO (United States)
2015-09-20
An experimental 30 kW boost composite converter is described in this paper. The composite converter architecture, which consists of a buck module, a boost module, and a dual active bridge module that operates as a DC transformer (DCX), leads to substantial reductions in losses at partial power points, and to significant improvements in weighted efficiency in applications that require wide variations in power and conversion ratio. A comprehensive loss model is developed, accounting for semiconductor conduction and switching losses, capacitor losses, as well as dc and ac losses in magnetic components. Based on the developed loss model, the module and system designs are optimized to maximize efficiency at a 50% power point. Experimental results for the 30 kW prototype demonstrate 98.5%peak efficiency, very high efficiency over wide ranges of power and voltage conversion ratios, as well as excellent agreements between model predictions and measured efficiency curves.
6. DOE/OER-sponsored basic research in high-efficiency photovoltaics
Energy Technology Data Exchange (ETDEWEB)
Deb, S.K.; Benner, J.P. [National Renewable Energy Lab., Golden, CO (United States)
1996-05-01
A high-efficiency photovoltaic project involving many of the national laboratories and several universities has been initiated under the umbrella of the U.S. Department of Energy (DOE) Center of Excellence for the Synthesis and Processing of Advanced Materials. The objectives of this project are to generate advances in fundamental scientific understanding that will impact the efficiency, cost and reliability of thin-film photovoltaic cells. The project is focused on two areas. (1) Silicon-Based Thin Films, in which key scientific and technological problems involving amorphous and polycrystalline silicon thin films will be addressed, and (2) Next-Generation Thin-Film Photovoltaics, which will be concerned with the possibilities of new advances and breakthroughs in the materials and physics of photovoltaics using non-silicon-based materials.
7. Development of Highly Efficient Grafting Technique and Synthesis of Natural Polymer-Based Graft Adsorbent
Energy Technology Data Exchange (ETDEWEB)
Ueki, Y; Seko, N; Tamada, M [Japan Atomic Energy Agency, Quantum Beam Science Directorate, Takasaki (Japan)
2012-09-15
In the framework of the CRP, Japan has focused on the development of fibrous adsorbents for removal of toxic metal ions and recovery of significant metal ions from industrial wastewater and streaming water. Graft polymerization was carried out by using gamma irradiation facility and electron beam accelerator. Emulsion grafting is a novel topic for synthesis of metal ion adsorbents which are prepared from fibrous trunk polymers such as polyethylene fibre and biodegradable nonwoven fabrics. The emulsion grafting, where monomer micelles are dispersed in water in the presence of surfactant, is a highly efficient and economic grafting technique as compared to general organic solvent system. The resultant cotton-based adsorbent has high adsorption efficiency and high adsorption capacity for Hg, besides, it is biodegradable. Polylactic acid can also be used as a trunk material for the grafting. (author)
8. High efficiency 40 K single-stage Stirling-type pulse tube cryocooler
Science.gov (United States)
Wu, X. L.; Chen, L. B.; Pan, C. Z.; Cui, C.; Wang, J. J.; Zhou, Y.
2017-12-01
A high efficiency single-stage Stirling-type coaxial pulse tube cryocooler (SPTC) operating at around 40 K has been designed, built and tested. The double-inlet and the inertance tubes together with the gas reservoir were adopted as the phase shifters. Under the conditions of 2.5 MPa charging pressure and 30 Hz operating frequency, the prototype has achieved a no-load temperature of 23.8 K with 330 W of electric input power at a rejection temperature of 279 K. When the input power increases to 400 W, it can achieve a cooling capacity of 4.7 W/40 K while rejecting heat at 279 K yielding an efficiency of 7.02% relative to Carnot. It achieves a cooling capacity of 5 W/40 K with an input power of 450 W. It takes 10 minutes for the SPTC to cool to its no-load temperature of 40 K from 295 K.
9. Highly efficient tandem organic light-emitting devices employing an easily fabricated charge generation unit
Science.gov (United States)
Yang, Huishan; Yu, Yaoyao; Wu, Lishuang; Qu, Biao; Lin, Wenyan; Yu, Ye; Wu, Zhijun; Xie, Wenfa
2018-02-01
We have realized highly efficient tandem organic light-emitting devices (OLEDs) employing an easily fabricated charge generation unit (CGU) combining 1,4,5,8,9,11-hexaazatriphenylene-hexacarbonitrile with ultrathin bilayers of CsN3 and Al. The charge generation and separation processes of the CGU have been demonstrated by studying the differences in the current density-voltage characteristics of external-carrier-excluding devices. At high luminances of 1000 and 10000 cd/m2, the current efficiencies of the phosphorescent tandem device are about 2.2- and 2.3-fold those of the corresponding single-unit device, respectively. Simultaneously, an efficient tandem white OLED exhibiting high color stability and warm white emission has also been fabricated.
10. Improved contact metallization for high efficiency EFG polycrystalline silicon solar cells
International Nuclear Information System (INIS)
Dube, C.E.; Gonsiorawski, R.C.
1990-01-01
Improvements in the performance of polycrystalline silicon solar cells based on a novel, laser patterned contact process are described. Small lots of cells having an average conversion efficiency of 14 + %, with several cells approaching 15%, are reported for cells of 45 cm 2 area. The high efficiency contact design is based on YAG laser patterning of the silicon nitride anti-reflection coating. The Cu metallization is done using light-induced plating, with the cell providing the driving voltage for the plating process. The Cu electrodeposits into the laser defined windows in the AR coating for reduced contact area, following which the Cu bridges on top of the Ar coating to form a continuous finger pattern. The higher cell conversion efficiency is attributed to reduced shadow loss, higher junction quality, and reduced metal-semiconductor interfacial area
11. Ultra-broadband and high-efficiency polarization conversion metasurface with multiple plasmon resonance modes
International Nuclear Information System (INIS)
Dong Guo-Xiang; Xia Song; Li Wei; Zhang An-Xue; Xu Zhuo; Wei Xiao-Yong; Shi Hong-Yu
2016-01-01
In this paper, we present a novel metasurface design that achieves a high-efficiency ultra-broadband cross polarization conversion. The metasurface is composed of an array of unit resonators, each of which combines an H-shaped structure and two rectangular metallic patches. Different plasmon resonance modes are excited in unit resonators and allow the polarization states to be manipulated. The bandwidth of the cross polarization converter is 82% of the central frequency, covering the range from 15.7 GHz to 37.5 GHz. The conversion efficiency of the innovative new design is higher than 90%. At 14.43 GHz and 40.95 GHz, the linearly polarized incident wave is converted into a circularly polarized wave. (paper)
12. High efficiency x-ray nanofocusing by the blazed stacking of binary zone plates
Science.gov (United States)
Mohacsi, I.; Karvinen, P.; Vartiainen, I.; Diaz, A.; Somogyi, A.; Kewish, C. M.; Mercere, P.; David, C.
2013-09-01
The focusing efficiency of binary Fresnel zone plate lenses is fundamentally limited and higher efficiency requires a multi step lens profile. To overcome the manufacturing problems of high resolution and high efficiency multistep zone plates, we investigate the concept of stacking two different binary zone plates in each other's optical near-field. We use a coarse zone plate with π phase shift and a double density fine zone plate with π/2 phase shift to produce an effective 4- step profile. Using a compact experimental setup with piezo actuators for alignment, we demonstrated 47.1% focusing efficiency at 6.5 keV using a pair of 500 μm diameter and 200 nm smallest zone width. Furthermore, we present a spatially resolved characterization method using multiple diffraction orders to identify manufacturing errors, alignment errors and pattern distortions and their effect on diffraction efficiency.
13. Simulation design of P–I–N-type all-perovskite solar cells with high efficiency
International Nuclear Information System (INIS)
Du Hui-Jing; Wang Wei-Chao; Gu Yi-Fan
2017-01-01
According to the good charge transporting property of perovskite, we design and simulate a p–i–n-type all-perovskite solar cell by using one-dimensional device simulator. The perovskite charge transporting layers and the perovskite absorber constitute the all-perovskite cell. By modulating the cell parameters, such as layer thickness values, doping concentrations and energy bands of n-, i-, and p-type perovskite layers, the all-perovskite solar cell obtains a high power conversion efficiency of 25.84%. The band matched cell shows appreciably improved performance with widen absorption spectrum and lowered recombination rate, so weobtain a high J sc of 32.47 mA/cm 2 . The small series resistance of the all-perovskite solar cell also benefits the high J sc . The simulation provides a novel thought of designing perovskite solar cells with simple producing process, low production cost and high efficient structure to solve the energy problem. (paper)
14. Research and development of a high efficiency gas-fired water heater. Volume 2. Task reports
Energy Technology Data Exchange (ETDEWEB)
Vasilakis, A.D.; Pearson, J.F.; Gerstmann, J.
1980-01-01
Design and development of a cost-effective high efficiency gas-fired water heater to attain a service efficiency of 70% (including the effect of exfiltration) and a service efficiency of 78% (excluding exfiltration) for a 75 GPD draw at a 90/sup 0/F temperature rise, with a stored water to conditioned air temperature difference of 80/sup 0/F, are described in detail. Based on concept evaluation, a non-powered natural draft water heater was chosen as the most cost-effective design to develop. The projected installed cost is $374 compared to$200 for a conventional unit. When the project water heater is compared to a conventional unit, it has a payback of 3.7 years and life cycle savings of \$350 to the consumer. A prototype water heater was designed, constructed, and tested. When operated with sealed combustion, the unit has a service efficiency of 66.4% (including the effect of exfiltration) below a burner input of 32,000 Btu/h. In the open combustion configuration, the unit operated at a measured efficiency of 66.4% Btu/h (excluding exfiltration). This compares with a service efficiency of 51.3% for a conventional water heater and 61% for a conventional high efficiency unit capable of meeting ASHRAE 90-75. Operational tests showed the unit performed well with no evidence of stacking or hot spots. It met or exceeded all capacity or usage tests specified in the program test plan and met all emission goals. Future work will concentrate on designing, building, and testing pre-production units. It is anticipated that both sealed combustion and open draft models will be pursued.
15. A Universal Method to Engineer Metal Oxide-Metal-Carbon Interface for Highly Efficient Oxygen Reduction.
Science.gov (United States)
Lv, Lin; Zha, Dace; Ruan, Yunjun; Li, Zhishan; Ao, Xiang; Zheng, Jie; Jiang, Jianjun; Chen, Hao Ming; Chiang, Wei-Hung; Chen, Jun; Wang, Chundong
2018-03-27
Oxygen is the most abundant element in the Earth's crust. The oxygen reduction reaction (ORR) is also the most important reaction in life processes and energy converting/storage systems. Developing techniques toward high-efficiency ORR remains highly desired and a challenge. Here, we report a N-doped carbon (NC) encapsulated CeO 2 /Co interfacial hollow structure (CeO 2 -Co-NC) via a generalized strategy for largely increased oxygen species adsorption and improved ORR activities. First, the metallic Co nanoparticles not only provide high conductivity but also serve as electron donors to largely create oxygen vacancies in CeO 2 . Second, the outer carbon layer can effectively protect cobalt from oxidation and dissociation in alkaline media and as well imparts its higher ORR activity. In the meanwhile, the electronic interactions between CeO 2 and Co in the CeO 2 /Co interface are unveiled theoretically by density functional theory calculations to justify the increased oxygen absorption for ORR activity improvement. The reported CeO 2 -Co-NC hollow nanospheres not only exhibit decent ORR performance with a high onset potential (922 mV vs RHE), half-wave potential (797 mV vs RHE), and small Tafel slope (60 mV dec -1 ) comparable to those of the state-of-the-art Pt/C catalysts but also possess long-term stability with a negative shift of only 7 mV of the half-wave potential after 2000 cycles and strong tolerance against methanol. This work represents a solid step toward high-efficient oxygen reduction.
16. Scalable Approach to Highly Efficient and Rapid Capacitive Deionization with CNT-Thread As Electrodes.
Science.gov (United States)
Moronshing, Maku; Subramaniam, Chandramouli
2017-11-22
A scalable route to highly efficient purification of water through capacitive deionization (CDI) is reported using CNT-thread as electrodes. Electro-sorption capacity (q e ) of 139 mg g -1 and average salt-adsorption rate (ASAR) of 2.78 mg g -1 min -1 achieved here is the highest among all known electrode materials and nonmembrane techniques, indicating efficient and rapid deionization. Such exceptional performance is achieved with feedstock concentrations (≤1000 ppm) where conventional techniques such as reverse osmosis and electrodialysis prove ineffective. Further, both cations (Na + , K + , Mg 2+ , and Ca 2+ ) and anions (Cl - , SO 4 2- and NO 3 - ) are removed with equally high efficiency (∼80%). Synergism between electrical conductivity (∼25 S cm -1 ), high specific surface area (∼900 m 2 g -1 ), porosity (0.7 nm, 3 nm) and hydrophilicity (contact angle ∼25°) in CNT-thread electrode enable superior contact with water, rapid formation of extensive electrical double layer and consequently efficient deionization. The tunable capacitance of the device (0.4-120 mF) and its high specific capacitance (∼27.2 F g -1 ) enable exceptional performance across a wide range of saline concentrations (50-1000 ppm). Facile regeneration of the electrode and reusability of the device is achieved for several cycles. The device demonstrated can desalinate water as it trickles down its surface because of gravity, thereby eliminating the requirement of any water pumping system. Finally, its portable adaptability is demonstrated by operating the device with an AA battery.
17. A compact and high efficiency GAGG well counter for radiocesium concentration measurements
Energy Technology Data Exchange (ETDEWEB)
Yamamoto, Seiichi, E-mail: s-yama@met.nagoya-u.ac.jp; Ogata, Yoshimune
2014-07-01
18. Highly efficient periodically poled KTP-isomorphs with large apertures and extreme domain aspect-ratios
Science.gov (United States)
Canalias, Carlota; Zukauskas, Andrius; Tjörnhamman, Staffan; Viotti, Anne-Lise; Pasiskevicius, Valdas; Laurell, Fredrik
2018-02-01
Since the early 1990's, a substantial effort has been devoted to the development of quasi-phased-matched (QPM) nonlinear devices, not only in ferroelectric oxides like LiNbO3, LiTaO3 and KTiOPO4 (KTP), but also in semiconductors as GaAs, and GaP. The technology to implement QPM structures in ferroelectric oxides has by now matured enough to satisfy the most basic frequency-conversion schemes without substantial modification of the poling procedures. Here, we present a qualitative leap in periodic poling techniques that allows us to demonstrate devices and frequency conversion schemes that were deemed unfeasible just a few years ago. Thanks to our short-pulse poling and coercive-field engineering techniques, we are able to demonstrate large aperture (5 mm) periodically poled Rb-doped KTP devices with a highly-uniform conversion efficiency over the whole aperture. These devices allow parametric conversion with energies larger than 60 mJ. Moreover, by employing our coercive-field engineering technique we fabricate highlyefficient sub-µm periodically poled devices, with periodicities as short as 500 nm, uniform over 1 mm-thick crystals, which allow us to realize mirrorless optical parametric oscillators with counter-propagating signal and idler waves. These novel devices present unique spectral and tuning properties, superior to those of conventional OPOs. Furthermore, our techniques are compatible with KTA, a KTP isomorph with extended transparency in the mid-IR range. We demonstrate that our highly-efficient PPKTA is superior both for mid-IR and for green light generation - as a result of improved transmission properties in the visible range. Our KTP-isomorph poling techniques leading to highly-efficient QPM devices will be presented. Their optical performance and attractive damage thresholds will be discussed.
19. Highly efficient retrograde gene transfer into motor neurons by a lentiviral vector pseudotyped with fusion glycoprotein.
Directory of Open Access Journals (Sweden)
Miyabi Hirano
Full Text Available The development of gene therapy techniques to introduce transgenes that promote neuronal survival and protection provides effective therapeutic approaches for neurological and neurodegenerative diseases. Intramuscular injection of adenoviral and adeno-associated viral vectors, as well as lentiviral vectors pseudotyped with rabies virus glycoprotein (RV-G, permits gene delivery into motor neurons in animal models for motor neuron diseases. Recently, we developed a vector with highly efficient retrograde gene transfer (HiRet by pseudotyping a human immunodeficiency virus type 1 (HIV-1-based vector with fusion glycoprotein B type (FuG-B or a variant of FuG-B (FuG-B2, in which the cytoplasmic domain of RV-G was replaced by the corresponding part of vesicular stomatitis virus glycoprotein (VSV-G. We have also developed another vector showing neuron-specific retrograde gene transfer (NeuRet with fusion glycoprotein C type, in which the short C-terminal segment of the extracellular domain and transmembrane/cytoplasmic domains of RV-G was substituted with the corresponding regions of VSV-G. These two vectors afford the high efficiency of retrograde gene transfer into different neuronal populations in the brain. Here we investigated the efficiency of the HiRet (with FuG-B2 and NeuRet vectors for retrograde gene transfer into motor neurons in the spinal cord and hindbrain in mice after intramuscular injection and compared it with the efficiency of the RV-G pseudotype of the HIV-1-based vector. The main highlight of our results is that the HiRet vector shows the most efficient retrograde gene transfer into both spinal cord and hindbrain motor neurons, offering its promising use as a gene therapeutic approach for the treatment of motor neuron diseases.
20. High-Efficiency, Multijunction Solar Cells for Large-Scale Solar Electricity Generation
Science.gov (United States)
Kurtz, Sarah
2006-03-01
A solar cell with an infinite number of materials (matched to the solar spectrum) has a theoretical efficiency limit of 68%. If sunlight is concentrated, this limit increases to about 87%. These theoretical limits are calculated using basic physics and are independent of the details of the materials. In practice, the challenge of achieving high efficiency depends on identifying materials that can effectively use the solar spectrum. Impressive progress has been made with the current efficiency record being 39%. Today's solar market is also showing impressive progress, but is still hindered by high prices. One strategy for reducing cost is to use lenses or mirrors to focus the light on small solar cells. In this case, the system cost is dominated by the cost of the relatively inexpensive optics. The value of the optics increases with the efficiency of the solar cell. Thus, a concentrator system made with 35%- 40%-efficient solar cells is expected to deliver 50% more power at a similar cost when compare with a system using 25%-efficient cells. Today's markets are showing an opportunity for large concentrator systems that didn't exist 5-10 years ago. Efficiencies may soon pass 40% and ultimately may reach 50%, providing a pathway to improved performance and decreased cost. Many companies are currently investigating this technology for large-scale electricity generation. The presentation will cover the basic physics and more practical considerations to achieving high efficiency as well as describing the current status of the concentrator industry. This work has been authored by an employee of the Midwest Research Institute under Contract No. DE- AC36-99GO10337 with the U.S. Department of Energy. The United States Government retains and the publisher, by accepting the article for publication, acknowledges that the United States Government retains a non-exclusive, paid-up, irrevocable, worldwide license to publish or reproduce the published form of this work, or allow | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 1, "mathjax_display_tex": 0, "mathjax_asciimath": 1, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.6685936450958252, "perplexity": 6236.46556777434}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2021-21/segments/1620243989819.92/warc/CC-MAIN-20210518094809-20210518124809-00354.warc.gz"} |
http://slideplayer.com/slide/3169305/ | # An Example of {AND, OR, Given that} Using a Normal Distribution
## Presentation on theme: "An Example of {AND, OR, Given that} Using a Normal Distribution"— Presentation transcript:
An Example of {AND, OR, Given that} Using a Normal Distribution
By Henry Mesa
Consider the following problem
Consider the following problem. The length of human pregnancy in days, has an average of 266 days, and a standard deviation of 16 days. The distribution is normal. Let the random variable X denote the length of a human pregnancy.
Consider the following problem
Consider the following problem. The length of human pregnancy in days, has an average of 266 days, and a standard deviation of 16 days. The distribution is normal. Let the random variable X denote the length of a human pregnancy. Let event A be a pregnancy lasts between 266 days and 298 days. Let event B be a pregnancy lasts between 250 days 282 days. Let event C be a pregnancy lasts 234 days or less.
No, they share the common days 266 to 282.
Consider the following problem. The length of human pregnancy in days, has an average of 266 days, and a standard deviation of 16 days. The distribution is normal. Let the random variable X denote the length of a human pregnancy. Let event A be a pregnancy lasts between 266 days and 298 days. Let event B be a pregnancy lasts between 250 days 282 days. Let event C be a pregnancy lasts 234 days or less. 1. Are events A and B disjoint? No, they share the common days 266 to 282.
Yes, they do not share any common days.
Consider the following problem. The length of human pregnancy in days, has an average of 266 days, and a standard deviation of 16 days. The distribution is normal. Let the random variable X denote the length of a human pregnancy. Let event A be a pregnancy lasts between 266 days and 298 days. Let event B be a pregnancy lasts between 250 days 282 days. Let event C be a pregnancy lasts 234 days or less. 2. Are events B and C disjoint? Yes, they do not share any common days.
Consider the following problem
Consider the following problem. The length of human pregnancy in days, has an average of 266 days, and a standard deviation of 16 days. The distribution is normal. Let the random variable X denote the length of a human pregnancy. Let event A be a pregnancy lasts between 266 days and 298 days. Let event B be a pregnancy lasts between 250 days 282 days. Let event C be a pregnancy lasts 234 days or less. 3. Calculate P(B OR C) P(X < 234 OR 250 < X < 282) = = P(Z < -2) + P( -1< Z< 0 ) = = Using rule
Consider the following problem
Consider the following problem. The length of human pregnancy in days, has an average of 266 days, and a standard deviation of 16 days. The distribution is normal. Let the random variable X denote the length of a human pregnancy. Let event A be a pregnancy lasts between 266 days and 298 days. Let event B be a pregnancy lasts between 250 days 282 days. Let event C be a pregnancy lasts 234 days or less. 3. Calculate P(B OR C) P(X < 234 OR 250 < X < 282) = = P(Z < -2) + P( -1< Z< 0 ) = =
Consider the following problem
Consider the following problem. The length of human pregnancy in days, has an average of 266 days, and a standard deviation of 16 days. The distribution is normal. Let the random variable X denote the length of a human pregnancy. Let event A be a pregnancy lasts between 266 days and 298 days. Let event B be a pregnancy lasts between 250 days 282 days. Let event C be a pregnancy lasts 234 days or less. 4. Calculate P(A OR B) P(250 < X < 282 OR 266 < X < 298) = P(250 < X < 298) = P( -1 < Z < 2 ) = = 0.815Using 68 – rule
Consider the following problem
Consider the following problem. The length of human pregnancy in days, has an average of 266 days, and a standard deviation of 16 days. The distribution is normal. Let the random variable X denote the length of a human pregnancy. Let event A be a pregnancy lasts between 266 days and 298 days. Let event B be a pregnancy lasts between 250 days 282 days. Let event C be a pregnancy lasts 234 days or less. 4. Calculate P(A OR B) P(P(250 < X < 282 OR 266 < X < 298) = P(250 < X < 298) = P( -1 < Z < 2 ) = =
Consider the following problem
Consider the following problem. The length of human pregnancy in days, has an average of 266 days, and a standard deviation of 16 days. The distribution is normal. Let the random variable X denote the length of a human pregnancy. Let event A be a pregnancy lasts between 266 days and 298 days. Let event B be a pregnancy lasts between 250 days 282 days. Let event C be a pregnancy lasts 234 days or less. 5. Calculate P(A AND B) P(250 < X < 282 AND 266 < X < 298) = P(266 < X < 282) = P(0 < Z < 1) = Using rule. =
Consider the following problem
Consider the following problem. The length of human pregnancy in days, has an average of 266 days, and a standard deviation of 16 days. The distribution is normal. Let the random variable X denote the length of a human pregnancy. Let event A be a pregnancy lasts between 266 days and 298 days. Let event B be a pregnancy lasts between 250 days 282 days. Let event C be a pregnancy lasts 234 days or less. 5. Calculate P(A AND B) P(250 < X < 282 AND 266 < X < 298) = P(266 < X < 282) = P(0 < Z < 1) =
There is no chance that one observation can meet both criteria.
Consider the following problem. The length of human pregnancy in days, has an average of 266 days, and a standard deviation of 16 days. The distribution is normal. Let the random variable X denote the length of a human pregnancy. Let event A be a pregnancy lasts between 266 days and 298 days. Let event B be a pregnancy lasts between 250 days 282 days. Let event C be a pregnancy lasts 234 days or less. 6. Calculate P(B AND C) P(X < 234 AND 250 < X < 282) = There is no chance that one observation can meet both criteria.
Consider the following problem
Consider the following problem. The length of human pregnancy in days, has an average of 266 days, and a standard deviation of 16 days. The distribution is normal. Let the random variable X denote the length of a human pregnancy. Let event A be a pregnancy lasts between 266 days and 298 days. Let event B be a pregnancy lasts between 250 days 282 days. Let event C be a pregnancy lasts 234 days or less. The new whole/sample space. 7. Calculate P(A | B) = 0.5 Given that the pregnancy lasted between 250 and 282 days, there is a 50 % chance that this particular pregnancy lasted between 266 and 298 days.
Consider the following problem
Consider the following problem. The length of human pregnancy in days, has an average of 266 days, and a standard deviation of 16 days. The distribution is normal. Let the random variable X denote the length of a human pregnancy. Let event A be a pregnancy lasts between 266 days and 298 days. Let event B be a pregnancy lasts between 250 days 282 days. Let event C be a pregnancy lasts 234 days or less. The new whole/sample space. 8. Calculate P(B | A) = Given that the pregnancy lasted between 266 and 298 days, there is a % chance that this particular pregnancy lasted between 250 and 282 days.
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https://blot.im/about/notes/programming/front-end-philosophy | # Front-end philosophy
Try and ship as little JavaScript down to the client. In general, I want to do as much computation as possible on the server, as little as possible on the client. This is because I control the server, but not the client.
I have nothing against JavaScript, the server is written in it. Just I want to exert as much control as possible over the resulting page the reader experiences. | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 1, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.4079574942588806, "perplexity": 878.0187619194434}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2021-31/segments/1627046156141.29/warc/CC-MAIN-20210805161906-20210805191906-00281.warc.gz"} |
https://www.physicsforums.com/threads/total-number-of-zeros.161506/ | # Total number of zeros.
1. Mar 19, 2007
### whatever84
Hi all,
Is there any number theory for calculating the total number of zeros ( NOT only the right zeros) in a big factorial without calculating the whole n!.
2. Mar 19, 2007
### matt grime
Removed wrong answer that ignored the bit in brackets in the OP.
Last edited: Mar 20, 2007
3. Mar 19, 2007
### CRGreathouse
Not that I can think of. Counting internal zeros instead of just number of factors of 5 is hard.
4. Apr 23, 2007
### whatever84
Are there any attempts to figure out how to count the total number of zeros?
5. May 13, 2007
### AlphaNumeric
Though it's utterly off the top of my head, could you do something with mod 10^n ?
For instance, if X mod 10^n = X mod 10^(n+1) then the n+1'th entry in X is 0. For instance, 301 mod 100 = 1 = 301 mod 10, so the 2nd entry of 301 is zero.
Unfortunately that's about the limit of my understanding of mods which aren't prime other than phrases like "Chinese Remainder Theorem". I imagine you could write a computer program to do the method I just suggested but it'd be much more convoluted than just computing n! and counting zeros.
6. May 15, 2007
### Zurtex
Lets take an example:
20! = 2432902008176640000
Therefore 20! has 7 0's.
Now it's easy enough to calculate the fact it has 4 end 0s, but the real question is it computationally efficient to consider looking at each of the other digits rather than just explicitly working it out.
Maybe, say you have the number of end 0's, lets call it k, and you're trying to work out the number of 0's in x!, then the obvious algorithm would be:
Code (Text):
For i = (k + 1) to (Floor[Log_10(x!)] - 1)
If Number of digits (x! mod 10^i) < i
counter = counter + 1
End If
End
Number of Zeros = counter + k
Obviously that's not a very efficient code. There are easy improvements you can make, like coming up with your own algorithm to work out x! mod 10^i, easy enough to make quite efficient, also the Log function has some obvious properties making Log_10(x!) very easy to work out. Actually, for very large x, you may want to look at stirlings approximation ( http://mathworld.wolfram.com/StirlingsApproximation.html ) and see if it's accurate enough.
But even so, you have to work out almost x!, with x! mod 10^(number of digits of x - 1), so I'm not sure it'd be any quicker at all, you'd need to test it. Also, ultimately multiplication isn't very hard task for computers, so working out x! isn't particularly difficult.
Last edited: May 15, 2007
7. Jul 3, 2007
### udwdreams
number of trailing zeroes
// computes number of trailing zeroes in n!
int TrailingZeros(int n) {
int num = 0;
while (n >= 5) {
n /= 5;
num += n;
}
return num;
}
The idea is that number factors 5 in p! / (5p)! is p. You can prove this by recurrence. Thus, you do not need to compute p!
8. Jul 3, 2007
### udwdreams
Working out x! is impossible for x large. 100! does not fit on an integer. Even using 64-bit integer won't take you very far if you need to compute N!
the program you have would overflow very quickly and return invalid results.
9. Jul 3, 2007
### Kummer
You can use a theorem referred to as "Legendre's Theorem"
$$n! = \prod_{p\leq n} p^{\sum_{k=1}^{\infty} [ n/p^k] }$$
This is based on the consequence that the total number of times $$p$$ (a prime) divides $$n!$$ is:
$$\sum_{k=1}^{\infty} \left[ \frac{n}{p^k} \right]$$. So the number of zero's the the minimum of the number of times 2 divides n! and 5 divides n! since 10 = 2*5. Furthermore, since 5>2 it means that the smaller number is the number of times 5 divides n!.
And so by Legendre's formula we have:
$$\sum_{k=1}^{\infty} \left[ \frac{n}{p^k} \right]$$
10. Jul 3, 2007
### Hurkyl
Staff Emeritus
Both of you should look at the opening post again; you answered the question that the opening poster specifically said he did not want answered.
Why limit yourself to 64-bit integers?
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 1, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.7164356708526611, "perplexity": 1446.3645132122374}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": false}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2018-22/segments/1526794872114.89/warc/CC-MAIN-20180528072218-20180528092218-00338.warc.gz"} |
http://www.ck12.org/tebook/Human-Biology-Reproduction-Teacher%2527s-Guide/section/9.3/ | <img src="https://d5nxst8fruw4z.cloudfront.net/atrk.gif?account=iA1Pi1a8Dy00ym" style="display:none" height="1" width="1" alt="" />
# 9.3: Activities and Answer Keys
Difficulty Level: At Grade Created by: CK-12
## Activity 8-1: What Are the Issues?
### PLAN
Summary This activity is a class discussion about abortion. Students use a combination of ready-made and self-made scenarios to examine the moral and ethical issues of this potentially emotional subject.
Objectives
Students:
\begin{align*}\checkmark\end{align*} clarify their personal views on abortion.
\begin{align*}\checkmark\end{align*} listen respectfully to the views of others.
Student Materials
• Activity Report (one copy per group)
Teacher Materials
• None if discussion is open to whole class
• One copy of Activity Report per group if group work is selected
The abortion issue can elicit emotional responses. Decide if you will handle the discussion as a whole class or by dividing the class into groups. If you divide the class into smaller groups, consider the groupings carefully.
If needed, define the term “moral issues.”
Estimated Time 40-45 minutes
This activity can be extended depending on class interest.
Interdisciplinary Connections
This activity has Guidance/Language Arts/Social Science/Science connections. It can be extended to include:
Language Arts or Social Studies Allow 2-3 days for groups to prepare an oral, written, or visual presentation on “Abortion: Is it ever right?” Limit oral presentations to 5 minutes. Groups should use factual information when possible to avoid a purely emotional response.
Prerequisites and Background Information
None required
### IMPLEMENT
Introduce Activity 8-1 by asking the class what they think makes an issue controversial. Can they list some controversial items that have been in the news the last few years? How should people discuss issues when they have strongly held differing views? Have they seen examples in the news of bad ways of disagreeing? Have they seen examples of positive ways? Review the ground rules for class discussions. Since these are sensitive issues it is recommended that the class be reminded that everyone is entitled to their views and beliefs. People should be understanding and respectful of other people's views. Address the issues-do not attack the person.
Steps 1-2 Ask the students to respond to the following question: “Is it ever okay to have an abortion?” Then tell them to put their responses away. At the end of the class discussion they can refer back to their papers to see if they have changed their minds and why.
Step 3 Read the directions to the Activity Report with your students. The introduction to this activity gives these scenarios:
a. A woman is raped and later discovers she is pregnant.
b. A pregnant woman feels she is not yet prepared to give birth and raise a child.
c. The pregnant daughter of an abusive parent was told that she would be beaten “within an inch of your life” if she ever got pregnant.
d. A doctor warns a pregnant mother that giving birth again could be fatal to her.
e. A young, pregnant woman is told by her boyfriend that she must get an abortion or he will leave her.
Students are then asked to write at least one realistic scenario involving a pregnant woman. These should be collected and screened for inclusion in the discussions.
Step 4 Using any or all of these scenarios, lead the class in a discussion of the moral dilemma of abortion. For each scenario, bring the following questions into the discussion:
a. What are the moral issues involved? Is abortion “right” or “wrong”?
b. Who decides if something is “right” or “wrong”?
c. Where does freedom of personal choice stop and responsibility to others start?
d. Whose interests are at stake? The mother's? That of the fetus? Society? How do these conflicts get solved and by whom?
e. When does the fetus become a “person”? Who decides? How do they decide?
f. Do developing fetuses have a right to be born?
g. Since we are all entitled to our religious and moral beliefs, how do we decide what law must apply to all people?
An alternative to a whole-class discussion is a group discussion. Give each group a scenario to discuss among themselves, each in turn, as the rest of the class listens. The class can then ask the group to respond to their questions at the end of the group discussion. This will extend the class time and focus the attention of the class on a variety of scenarios.
Conclude Activity 8-1 by allowing the students about five minutes to refer back to the original question they answered. Did they change their minds? Why? This can be their private, quiet time to reflect, and to calm down before their next class period.
### ASSESS
Use student responses during class discussions and the responses on the Activity Report to assess if students can
\begin{align*}\checkmark\end{align*} identify the complexity of the issues surrounding abortion.
\begin{align*}\checkmark\end{align*} explain the wide range of beliefs.
\begin{align*}\checkmark\end{align*} explain why these questions have no “absolute” answers.
\begin{align*}\checkmark\end{align*} identify the factors that affect an individual's opinion about abortion.
Write a letter to someone who is contemplating an abortion. In your letter, discuss your personal views about abortion.
• Sample answers to these questions will be provided upon request. Please send an email to teachers-requests@ck12.org to request sample answers.
1. What are two common side effects of the IUD?
2. At what point in pregnancy do abortions become illegal in this country?
3. What does pro-life mean? What does pro-choice mean?
## Activity 8-1 Report: What Are the Issues? (Student Reproducible)
Instructions
Your teacher will set the “ground rules” for your group discussion on abortion. Then, your teacher will assign your group a scenario involving a pregnant woman who must make a decision regarding abortion.
Think about and discuss the following as they apply to the scenario you are given:
• What are the moral issues involved? By choosing or not choosing to have an abortion is she making the “right” or “wrong” choice?
• Who decides if this choice is “right” or “wrong”?
• Where does freedom of personal choice stop and responsibility to others begin?
• Whose interests are involved? The mother's? That of the fetus? Society? How do these conflicts get resolved?
• When does the fetus become a “person”? Who decides? How?
• Does this developing fetus have a right to be born?
• Since we are all entitled to our religious and moral beliefs, how do we decide what law must apply to all people?
• Is it ever OK to have an abortion?
There are no easy answers to these questions. Your generation, like the present generation of adults, has to face the challenging issues of abortion. So, give serious thought to these issues now.
6 , 7 , 8
## Date Created:
Sep 08, 2014
Sep 08, 2014
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https://statproofbook.github.io/I/Proof_by_Number | ID Shortcut Theorem Author Date
P0 -temp- Proof Template StatProofBook 2019-09-27
P1 mvn-ltt Linear transformation theorem for the multivariate normal distribution JoramSoch 2019-08-27
P2 mlr-ols Ordinary least squares for multiple linear regression JoramSoch 2019-09-27
P3 lme-anc Partition of the log model evidence into accuracy and complexity JoramSoch 2019-09-27
P4 bayes-th Bayes’ theorem JoramSoch 2019-09-27
P5 mse-bnv Partition of the mean squared error into bias and variance JoramSoch 2019-11-27
P6 ng-kl Kullback-Leibler divergence for the normal-gamma distribution JoramSoch 2019-12-06
P7 glm-mle Maximum likelihood estimation for the general linear model JoramSoch 2019-12-06
P8 rsq-der Derivation of R² and adjusted R² JoramSoch 2019-12-06
P9 blr-prior Conjugate prior distribution for Bayesian linear regression JoramSoch 2020-01-03
P10 blr-post Posterior distribution for Bayesian linear regression JoramSoch 2020-01-03
P11 blr-lme Log model evidence for Bayesian linear regression JoramSoch 2020-01-03
P12 bayes-rule Bayes’ rule JoramSoch 2020-01-06
P13 lme-der Derivation of the log model evidence JoramSoch 2020-01-06
P14 rsq-mll Relationship between R² and maximum log-likelihood JoramSoch 2020-01-08
P15 norm-mean Mean of the normal distribution JoramSoch 2020-01-09
P16 norm-med Median of the normal distribution JoramSoch 2020-01-09
P17 norm-mode Mode of the normal distribution JoramSoch 2020-01-09
P18 norm-var Variance of the normal distribution JoramSoch 2020-01-09
P19 dmi-mce Relation of mutual information to marginal and conditional entropy JoramSoch 2020-01-13
P20 dmi-mje Relation of mutual information to marginal and joint entropy JoramSoch 2020-01-13
P21 dmi-jce Relation of mutual information to joint and conditional entropy JoramSoch 2020-01-13
P22 bern-mean Mean of the Bernoulli distribution JoramSoch 2020-01-16
P23 bin-mean Mean of the binomial distribution JoramSoch 2020-01-16
P24 cat-mean Mean of the categorical distribution JoramSoch 2020-01-16
P25 mult-mean Mean of the multinomial distribution JoramSoch 2020-01-16
P26 matn-mvn Equivalence of matrix-normal distribution and multivariate normal distribution JoramSoch 2020-01-20
P27 poiss-mle Maximum likelihood estimation for Poisson-distributed data JoramSoch 2020-01-20
P28 beta-mome Method of moments for beta-distributed data JoramSoch 2020-01-22
P29 bin-prior Conjugate prior distribution for binomial observations JoramSoch 2020-01-23
P30 bin-post Posterior distribution for binomial observations JoramSoch 2020-01-24
P31 bin-lme Log model evidence for binomial observations JoramSoch 2020-01-24
P32 bic-der Derivation of the Bayesian information criterion JoramSoch 2020-01-26
P33 norm-pdf Probability density function of the normal distribution JoramSoch 2020-01-27
P34 mvn-pdf Probability density function of the multivariate normal distribution JoramSoch 2020-01-27
P35 mvn-marg Marginal distributions of the multivariate normal distribution JoramSoch 2020-01-29
P36 ng-marg Marginal distributions of the normal-gamma distribution JoramSoch 2020-01-29
P37 cuni-pdf Probability density function of the continuous uniform distribution JoramSoch 2020-01-31
P38 cuni-cdf Cumulative distribution function of the continuous uniform distribution JoramSoch 2020-01-02
P39 cuni-qf Quantile function of the continuous uniform distribution JoramSoch 2020-01-02
P40 mlr-ols2 Ordinary least squares for multiple linear regression JoramSoch 2020-02-03
P41 poissexp-prior Conjugate prior distribution for the Poisson distribution with exposure values JoramSoch 2020-02-04
P42 poissexp-post Posterior distribution for the Poisson distribution with exposure values JoramSoch 2020-02-04
P43 poissexp-lme Log model evidence for the Poisson distribution with exposure values JoramSoch 2020-02-04
P44 ng-pdf Probability density function of the normal-gamma distribution JoramSoch 2020-02-07
P45 gam-pdf Probability density function of the gamma distribution JoramSoch 2020-02-08
P46 exp-pdf Probability density function of the exponential distribution JoramSoch 2020-02-08
P47 exp-mean Mean of the exponential distribution JoramSoch 2020-02-10
P48 exp-cdf Cumulative distribution function of the exponential distribution JoramSoch 2020-02-11
P49 exp-med Median of the exponential distribution JoramSoch 2020-02-11
P50 exp-qf Quantile function of the exponential distribution JoramSoch 2020-02-12
P51 exp-mode Mode of the exponential distribution JoramSoch 2020-02-12
P52 mean-nonneg Non-negativity of the expected value JoramSoch 2020-02-13
P53 mean-lin Linearity of the expected value JoramSoch 2020-02-13
P54 mean-mono Monotonicity of the expected value JoramSoch 2020-02-17
P55 mean-mult (Non-)Multiplicativity of the expected value JoramSoch 2020-02-17
P56 ci-wilks Construction of confidence intervals using Wilks’ theorem JoramSoch 2020-02-19
P57 ent-nonneg Non-negativity of the Shannon entropy JoramSoch 2020-02-19
P58 cmi-mcde Relation of continuous mutual information to marginal and conditional differential entropy JoramSoch 2020-02-21
P59 cmi-mjde Relation of continuous mutual information to marginal and joint differential entropy JoramSoch 2020-02-21
P60 cmi-jcde Relation of continuous mutual information to joint and conditional differential entropy JoramSoch 2020-02-21
P61 resvar-bias Maximum likelihood estimator of variance is biased JoramSoch 2020-02-24
P62 resvar-unb Construction of unbiased estimator for variance JoramSoch 2020-02-25
P63 snr-rsq Relationship between signal-to-noise ratio and R² JoramSoch 2020-02-26
P64 lbf-lme Log Bayes factor in terms of log model evidences JoramSoch 2020-02-27
P65 lfe-lme Log family evidences in terms of log model evidences JoramSoch 2020-02-27
P66 pmp-lme Posterior model probabilities in terms of log model evidences JoramSoch 2020-02-27
P67 bma-lme Bayesian model averaging in terms of log model evidences JoramSoch 2020-02-27
P68 dent-neg Differential entropy can be negative JoramSoch 2020-03-02
P69 exp-gam Exponential distribution is a special case of gamma distribution JoramSoch 2020-03-02
P70 matn-pdf Probability density function of the matrix-normal distribution JoramSoch 2020-03-02
P71 norm-mgf Moment-generating function of the normal distribution JoramSoch 2020-03-03
P72 logreg-lonp Log-odds and probability in logistic regression JoramSoch 2020-03-03
P73 pmp-lbf Posterior model probability in terms of log Bayes factor JoramSoch 2020-03-03
P74 pmp-bf Posterior model probabilities in terms of Bayes factors JoramSoch 2020-03-03
P75 mlr-mat Transformation matrices for ordinary least squares JoramSoch 2020-03-09
P76 mlr-pss Partition of sums of squares in ordinary least squares JoramSoch 2020-03-09
P77 mlr-wls Weighted least squares for multiple linear regression JoramSoch 2020-03-11
P78 mlr-mle Maximum likelihood estimation for multiple linear regression JoramSoch 2020-03-11
P79 mult-prior Conjugate prior distribution for multinomial observations JoramSoch 2020-03-11
P80 mult-post Posterior distribution for multinomial observations JoramSoch 2020-03-11
P81 mult-lme Log model evidence for multinomial observations JoramSoch 2020-03-11
P82 cuni-mean Mean of the continuous uniform distribution JoramSoch 2020-03-16
P83 cuni-med Median of the continuous uniform distribution JoramSoch 2020-03-16
P84 cuni-med Mode of the continuous uniform distribution JoramSoch 2020-03-16
P85 norm-cdf Cumulative distribution function of the normal distribution JoramSoch 2020-03-20
P86 norm-cdfwerf Expression of the cumulative distribution function of the normal distribution without the error function JoramSoch 2020-03-20
P87 norm-qf Quantile function of the normal distribution JoramSoch 2020-03-20
P88 mvn-cond Conditional distributions of the multivariate normal distribution JoramSoch 2020-03-20
P89 jl-lfnprior Joint likelihood is the product of likelihood function and prior density JoramSoch 2020-05-05
P90 post-jl Posterior density is proportional to joint likelihood JoramSoch 2020-05-05
P91 ml-jl Marginal likelihood is a definite integral of joint likelihood JoramSoch 2020-05-05
P92 mvn-kl Kullback-Leibler divergence for the multivariate normal distribution JoramSoch 2020-05-05
P93 gam-kl Kullback-Leibler divergence for the gamma distribution JoramSoch 2020-05-05
P94 beta-pdf Probability density function of the beta distribution JoramSoch 2020-05-05
P95 dir-pdf Probability density function of the Dirichlet distribution JoramSoch 2020-05-05
P96 bern-pmf Probability mass function of the Bernoulli distribution JoramSoch 2020-05-11
P97 bin-pmf Probability mass function of the binomial distribution JoramSoch 2020-05-11
P98 cat-pmf Probability mass function of the categorical distribution JoramSoch 2020-05-11
P99 mult-pmf Probability mass function of the multinomial distribution JoramSoch 2020-05-11
P100 mvn-dent Differential entropy of the multivariate normal distribution JoramSoch 2020-05-14
P101 norm-dent Differential entropy of the normal distribution JoramSoch 2020-05-14
P102 poiss-pmf Probability mass function of the Poisson distribution JoramSoch 2020-05-14
P103 mean-nnrvar Expected value of a non-negative random variable JoramSoch 2020-05-18
P104 var-mean Partition of variance into expected values JoramSoch 2020-05-19
P105 logreg-pnlo Probability and log-odds in logistic regression JoramSoch 2020-05-19
P106 glm-ols Ordinary least squares for the general linear model JoramSoch 2020-05-19
P107 glm-wls Weighted least squares for the general linear model JoramSoch 2020-05-19
P108 gam-mean Mean of the gamma distribution JoramSoch 2020-05-19
P109 gam-var Variance of the gamma distribution JoramSoch 2020-05-19
P110 gam-logmean Logarithmic expectation of the gamma distribution JoramSoch 2020-05-25
P111 norm-snorm Relationship between normal distribution and standard normal distribution JoramSoch 2020-05-26
P112 gam-sgam Relationship between gamma distribution and standard gamma distribution JoramSoch 2020-05-26
P113 kl-ent Relation of Kullback-Leibler divergence to entropy JoramSoch 2020-05-27
P114 kl-dent Relation of continuous Kullback-Leibler divergence to differential entropy JoramSoch 2020-05-27
P115 kl-inv Invariance of the Kullback-Leibler divergence under parameter transformation JoramSoch 2020-05-28
P116 kl-add Additivity of the Kullback-Leibler divergence for independent distributions JoramSoch 2020-05-31
P117 kl-nonneg Non-negativity of the Kullback-Leibler divergence JoramSoch 2020-05-31
P118 cov-mean Partition of covariance into expected values JoramSoch 2020-06-02
P119 cov-corr Relationship between covariance and correlation JoramSoch 2020-06-02
P120 covmat-mean Partition of a covariance matrix into expected values JoramSoch 2020-06-06
P121 covmat-corrmat Relationship between covariance matrix and correlation matrix JoramSoch 2020-06-06
P122 precmat-corrmat Relationship between precision matrix and correlation matrix JoramSoch 2020-06-06
P123 var-nonneg Non-negativity of the variance JoramSoch 2020-06-06
P124 var-const Variance of constant is zero JoramSoch 2020-06-27
P126 var-inv Invariance of the variance under addition of a constant JoramSoch 2020-07-07
P127 var-scal Scaling of the variance upon multiplication with a constant JoramSoch 2020-07-07
P128 var-sum Variance of the sum of two random variables JoramSoch 2020-07-07
P129 var-lincomb Variance of the linear combination of two random variables JoramSoch 2020-07-07
P130 var-add Additivity of the variance for independent random variables JoramSoch 2020-07-07
P131 mean-qf Expectation of a quadratic form JoramSoch 2020-07-13
P132 lfe-der Derivation of the log family evidence JoramSoch 2020-07-13
P133 blr-pp Posterior probability of the alternative hypothesis for Bayesian linear regression JoramSoch 2020-07-17
P134 blr-pcr Posterior credibility region against the omnibus null hypothesis for Bayesian linear regression JoramSoch 2020-07-17
P135 mlr-idem Projection matrix and residual-forming matrix are idempotent JoramSoch 2020-07-22
P136 mlr-wls2 Weighted least squares for multiple linear regression JoramSoch 2020-07-22
P137 lbf-der Derivation of the log Bayes factor JoramSoch 2020-07-22
P138 mean-lotus Law of the unconscious statistician JoramSoch 2020-07-22
P139 pmp-der Derivation of the posterior model probability JoramSoch 2020-07-28
P140 duni-pmf Probability mass function of the discrete uniform distribution JoramSoch 2020-07-28
P141 duni-cdf Cumulative distribution function of the discrete uniform distribution JoramSoch 2020-07-28
P142 duni-qf Quantile function of the discrete uniform distribution JoramSoch 2020-07-28
P143 bma-der Derivation of Bayesian model averaging JoramSoch 2020-08-03
P144 matn-trans Transposition of a matrix-normal random variable JoramSoch 2020-08-03
P145 matn-ltt Linear transformation theorem for the matrix-normal distribution JoramSoch 2020-08-03
P146 ng-cond Conditional distributions of the normal-gamma distribution JoramSoch 2020-08-05
P147 kl-nonsymm Non-symmetry of the Kullback-Leibler divergence JoramSoch 2020-08-11
P148 kl-conv Convexity of the Kullback-Leibler divergence JoramSoch 2020-08-11
P149 ent-conc Concavity of the Shannon entropy JoramSoch 2020-08-11
P150 entcross-conv Convexity of the cross-entropy JoramSoch 2020-08-11
P151 poiss-mean Mean of the Poisson distribution JoramSoch 2020-08-19
P152 norm-fwhm Full width at half maximum for the normal distribution JoramSoch 2020-08-19
P153 mom-mgf Moment in terms of moment-generating function JoramSoch 2020-08-19
P154 mgf-ltt Linear transformation theorem for the moment-generating function JoramSoch 2020-08-19
P155 mgf-lincomb Moment-generating function of linear combination of independent random variables JoramSoch 2020-08-19
P156 bf-sddr Savage-Dickey Density Ratio for computing Bayes Factors tomfaulkenberry 2020-08-26
P157 bf-ep Encompassing Prior Method for computing Bayes Factors tomfaulkenberry 2020-09-02
P158 cov-ind Covariance of independent random variables JoramSoch 2020-09-03
P159 mblr-prior Conjugate prior distribution for multivariate Bayesian linear regression JoramSoch 2020-09-03
P160 mblr-post Posterior distribution for multivariate Bayesian linear regression JoramSoch 2020-09-03
P161 mblr-lme Log model evidence for multivariate Bayesian linear regression JoramSoch 2020-09-03
P162 wald-pdf Probability density function of the Wald distribution tomfaulkenberry 2020-09-04
P163 bf-trans Transitivity of Bayes Factors tomfaulkenberry 2020-09-07
P164 gibbs-ineq Gibbs’ inequality JoramSoch 2020-09-09
P165 logsum-ineq Log sum inequality JoramSoch 2020-09-09
P166 kl-nonneg2 Non-negativity of the Kullback-Leibler divergence JoramSoch 2020-09-09
P167 momcent-1st First central moment is zero JoramSoch 2020-09-09
P168 wald-mgf Moment-generating function of the Wald distribution tomfaulkenberry 2020-09-13
P169 wald-mean Mean of the Wald distribution tomfaulkenberry 2020-09-13
P170 wald-var Variance of the Wald distribution tomfaulkenberry 2020-09-13
P171 momraw-1st First raw moment is mean JoramSoch 2020-10-08
P172 momraw-2nd Relationship between second raw moment, variance and mean JoramSoch 2020-10-08
P173 momcent-2nd Second central moment is variance JoramSoch 2020-10-08
P174 chi2-gam Chi-squared distribution is a special case of gamma distribution kjpetrykowski 2020-10-12
P175 chi2-mom Moments of the chi-squared distribution kjpetrykowski 2020-10-13
P176 norm-snorm2 Relationship between normal distribution and standard normal distribution JoramSoch 2020-10-15
P177 gam-sgam2 Relationship between gamma distribution and standard gamma distribution JoramSoch 2020-10-15
P178 gam-cdf Cumulative distribution function of the gamma distribution JoramSoch 2020-10-15
P179 gam-xlogx Expected value of x times ln(x) for a gamma distribution JoramSoch 2020-10-15
P180 norm-snorm3 Relationship between normal distribution and standard normal distribution JoramSoch 2020-10-22
P181 dir-ep Exceedance probabilities for the Dirichlet distribution JoramSoch 2020-10-22
P182 dir-mle Maximum likelihood estimation for Dirichlet-distributed data JoramSoch 2020-10-22
P183 cdf-sifct Cumulative distribution function of a strictly increasing function of a random variable JoramSoch 2020-10-29
P184 pmf-sifct Probability mass function of a strictly increasing function of a discrete random variable JoramSoch 2020-10-29
P185 pdf-sifct Probability density function of a strictly increasing function of a continuous random variable JoramSoch 2020-10-29
P186 cdf-sdfct Cumulative distribution function of a strictly decreasing function of a random variable JoramSoch 2020-11-06
P187 pmf-sdfct Probability mass function of a strictly decreasing function of a discrete random variable JoramSoch 2020-11-06
P188 pdf-sdfct Probability density function of a strictly decreasing function of a continuous random variable JoramSoch 2020-11-06
P189 cdf-pmf Cumulative distribution function in terms of probability mass function of a discrete random variable JoramSoch 2020-11-12
P190 cdf-pdf Cumulative distribution function in terms of probability density function of a continuous random variable JoramSoch 2020-11-12
P191 pdf-cdf Probability density function is first derivative of cumulative distribution function JoramSoch 2020-11-12
P192 qf-cdf Quantile function is inverse of strictly monotonically increasing cumulative distribution function JoramSoch 2020-11-12
P193 norm-kl Kullback-Leibler divergence for the normal distribution JoramSoch 2020-11-19
P194 gam-qf Quantile function of the gamma distribution JoramSoch 2020-11-19
P195 beta-cdf Cumulative distribution function of the beta distribution JoramSoch 2020-11-19
P196 norm-gi Gaussian integral JoramSoch 2020-11-25
P197 chi2-pdf Probability density function of the chi-squared distribution JoramSoch 2020-11-25
P198 beta-mgf Moment-generating function of the beta distribution JoramSoch 2020-11-25
P199 dent-inv Invariance of the differential entropy under addition of a constant JoramSoch 2020-12-02
P200 dent-add Addition of the differential entropy upon multiplication with a constant JoramSoch 2020-12-02
P201 ug-prior Conjugate prior distribution for the univariate Gaussian JoramSoch 2021-03-03
P202 ug-post Posterior distribution for the univariate Gaussian JoramSoch 2021-03-03
P203 ug-lme Log model evidence for the univariate Gaussian JoramSoch 2021-03-03
P204 ug-ttest1 One-sample t-test for independent observations JoramSoch 2021-03-12
P205 ug-ttest2 Two-sample t-test for independent observations JoramSoch 2021-03-12
P206 ug-ttestp Paired t-test for dependent observations JoramSoch 2021-03-12
P207 ugkv-mle Maximum likelihood estimation for the univariate Gaussian with known variance JoramSoch 2021-03-24
P208 ugkv-ztest1 One-sample z-test for independent observations JoramSoch 2021-03-24
P209 ugkv-ztest2 Two-sample z-test for independent observations JoramSoch 2021-03-24
P210 ugkv-ztestp Paired z-test for dependent observations JoramSoch 2021-03-24
P211 ugkv-prior Conjugate prior distribution for the univariate Gaussian with known variance JoramSoch 2021-03-24
P212 ugkv-post Posterior distribution for the univariate Gaussian with known variance JoramSoch 2021-03-24
P213 ugkv-lme Log model evidence for the univariate Gaussian with known variance JoramSoch 2021-03-24
P214 ugkv-anc Accuracy and complexity for the univariate Gaussian with known variance JoramSoch 2021-03-24
P215 ugkv-lbf Log Bayes factor for the univariate Gaussian with known variance JoramSoch 2021-03-24
P216 ugkv-lbfmean Expectation of the log Bayes factor for the univariate Gaussian with known variance JoramSoch 2021-03-24
P217 ugkv-cvlme Cross-validated log model evidence for the univariate Gaussian with known variance JoramSoch 2021-03-24
P218 ugkv-cvlbf Cross-validated log Bayes factor for the univariate Gaussian with known variance JoramSoch 2021-03-24
P219 ugkv-cvlbfmean Expectation of the cross-validated log Bayes factor for the univariate Gaussian with known variance JoramSoch 2021-03-24
P220 cdf-pit Probability integral transform using cumulative distribution function JoramSoch 2021-04-07
P221 cdf-itm Inverse transformation method using cumulative distribution function JoramSoch 2021-04-07
P222 cdf-dt Distributional transformation using cumulative distribution function JoramSoch 2021-04-07
P223 ug-mle Maximum likelihood estimation for the univariate Gaussian JoramSoch 2021-04-16
P224 poissexp-mle Maximum likelihood estimation for the Poisson distribution with exposure values JoramSoch 2021-04-16
P225 poiss-prior Conjugate prior distribution for Poisson-distributed data JoramSoch 2020-04-21
P226 poiss-post Posterior distribution for Poisson-distributed data JoramSoch 2020-04-21
P227 poiss-lme Log model evidence for Poisson-distributed data JoramSoch 2020-04-21
P228 beta-mean Mean of the beta distribution JoramSoch 2021-04-29
P229 beta-var Variance of the beta distribution JoramSoch 2021-04-29
P230 poiss-var Variance of the Poisson distribution JoramSoch 2021-04-29
P231 mvt-f Relationship between multivariate t-distribution and F-distribution JoramSoch 2021-05-04
P232 nst-t Relationship between non-standardized t-distribution and t-distribution JoramSoch 2021-05-11
P233 norm-chi2 Relationship between normal distribution and chi-squared distribution JoramSoch 2021-05-20
P234 norm-t Relationship between normal distribution and t-distribution JoramSoch 2021-05-27
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P236 mvn-ind Necessary and sufficient condition for independence of multivariate normal random variables JoramSoch 2021-06-02 | {"extraction_info": {"found_math": false, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.9970188736915588, "perplexity": 8992.768963370034}, "config": {"markdown_headings": false, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2021-25/segments/1623487607143.30/warc/CC-MAIN-20210613071347-20210613101347-00333.warc.gz"} |
https://www.physicsforums.com/threads/log-prbolems.318348/ | # Log prbolems
1. Jun 6, 2009
### parabol
1. The problem statement, all variables and given/known data
1/2*log(5)(x^2-1)=1/4+1/2log(5)(x-1)
I have put the base to the log in the first set of brackets following log.
The question is simply solve for x the equation
3. The attempt at a solution
I firstly moved the logs onto the smae side and then multiplied both sides by1/2 (not shown) thus giving
log(5)(x^2-1)-log(5)(x-1)=1/2
log(5)((x^2-1)/(x-1))=1/2
Am i right in the saying the follwoing is the next step?
(x2-1)/(x-1)=5^(1/2)
If I am then can someone please help me understand how I am supposed to simplify the equaiton down to give a single x.
2. Jun 6, 2009
### Bohrok
Re: Log problems
Assuming that log(5) is log5, that is right. How can you rewrite
$$\frac{x^2-1} {x-1}$$
specifically the numerator?
3. Jun 6, 2009
### parabol
That was exactly what I meant with regards to the base of the log.
I'm sorry I don't follow. I think I am looking to hard into this problem as I can see no way of simplifying (x2-1)/(x-1)
4. Jun 6, 2009
### Bohrok
Do you know how to factor x2 - 1?
5. Jun 6, 2009
### HallsofIvy
Staff Emeritus
You have
$$\frac{x^2- 1}{x- 1}= \sqrt{5}$$
What Bohrok is suggesting is that you factor the numerator. There is a simple cancelation.
6. Jun 7, 2009
### parabol
All sorted now.
Thanks very much for the sanity checks with this.
Similar Discussions: Log prbolems | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 1, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.8191655874252319, "perplexity": 2218.487615443769}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2017-51/segments/1512948521188.19/warc/CC-MAIN-20171213030444-20171213050444-00203.warc.gz"} |
https://www.sintef.no/en/all-employees/employee/?empid=2276 | Jon Are Wold Suul
Research Scientist
Phone: 930 06 982
Email:
Department: Energy Systems
Office: Trondheim
Publications and responsibilities
Publication
https://www.sintef.no/en/publications/publication/?pubid=CRIStin+1753560
Safety-critical power conversion systems play a major role in the paradigm shift towards more electric aircraft (MEA) architectures. This paper reviews the electrical machines and their power electronic systems that are currently competing in the application of integrated starter-generators (S/Gs) i...
Authors Nøland Jonas Kristiansen Leandro Matteo Suul Jon Are Wold Molinas Cabrera Maria Marta Nilssen Robert
Year 2019
Type Part of a book/report
Publication
https://www.sintef.no/en/publications/publication/?pubid=CRIStin+1753557
This paper presents a comparative eigenvalue analysis of the stability characteristics and small signal dynamics of four different control strategies for Synchronous Machine Emulation (SME) by power electronic converters, considering a Synchronous Machine (SM) as the benchmark system. The four SME t...
Authors Unamuno Eneko Suul Jon Are Wold Molinas Cabrera Maria Marta Barrena Jon Andoni
Year 2019
Type Part of a book/report
Publication
https://www.sintef.no/en/publications/publication/?pubid=CRIStin+1753553
This paper presents an experimental performance evaluation of different control strategies for providing virtual inertia from power electronic converters. The evaluation is based on a laboratory-scale prototype of a point-to-point HVDC transmission system with Modular Multilevel Converters (MMCs). O...
Authors D'Arco Salvatore Nguyen Tuan Thanh Suul Jon Are Wold
Year 2019
Type Part of a book/report
Publication
https://www.sintef.no/en/publications/publication/?pubid=CRIStin+1753487
This paper presents a technique for damping of oscillations in ac grids by control of VSC-HVDC links. The effect of the proposed controller is equivalent to a mechanical friction between two asynchronous networks (modelled as rotating masses) interconnected by the HVDC link. Therefore, the dynamics ...
Authors Rodriguez-Cabero Alberto Roldan-Pérez Javier Prodanovic Milan Suul Jon Are Wold D'Arco Salvatore
Year 2019
Type Part of a book/report
Publication
https://www.sintef.no/en/publications/publication/?pubid=CRIStin+1753469
This paper presents a distributed converter interface for the road-side infrastructure of dynamic inductive power transfer (IPT) systems for roadway-powered electric vehicles (RPEV). The proposed system configuration is based on a modular multilevel topology, with each individual module supplying po...
Authors Guidi Giuseppe D'Arco Salvatore Suul Jon Are Wold
Year 2019
Type Part of a book/report
Publication
https://www.sintef.no/en/publications/publication/?pubid=CRIStin+1752275
This paper presents a control approach for HVDC interconnections that provides damping of frequency oscillations in asynchronous ac grids by introducing a virtual friction for coupling their inertial dynamics. The HVDC interconnection is modelled by using the concept of common and differential power...
Authors Rodriguez-Cabero Alberto Perez Javier Prodanovic Milan Suul Jon Are Wold D'Arco Salvatore
Year 2019
Type Journal publication
Publication
https://www.sintef.no/en/publications/publication/?pubid=CRIStin+1751864
This paper introduces an approach for frequency-dependent pi-section (FD- $\pi$ ) modelling of ac cables which enables a time-invariant state-space representation that accounts for the frequency-dependent cable characteristics. The proposed approach relies on vector fitting to obtain parametric valu...
Authors D'Arco Salvatore Suul Jon Are Wold Beerten Jef
Year 2019
Type Part of a book/report
Publication
https://www.sintef.no/en/publications/publication/?pubid=CRIStin+1718035
This paper presents a system configuration for transformer-less grid integration of large-scale charging infrastructures for electric vehicles (EVs) with wireless inductive charging. The proposed configuration relies on a Modular Multilevel Converter (MMC) topology as the grid interface of the charg...
Authors Guidi Giuseppe D'Arco Salvatore Suul Jon Are Wold Ryosuke Iso Itoh Jun-Ichi
Year 2019
Type Part of a book/report
Publication
https://www.sintef.no/en/publications/publication/?pubid=CRIStin+1716063
This paper analyses the small-signal dynamics of a series-series compensated inductive charging system with a passive diode rectifier interfaced directly to a battery on the receiving side. The analyzed system is designed for utilizing the constant voltage load (CVL) characteristics of the battery t...
Authors Torsgård Ernst Guidi Giuseppe Suul Jon Are Wold
Year 2019
Type Part of a book/report | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 1, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.5560794472694397, "perplexity": 12741.03809383821}, "config": {"markdown_headings": false, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 20, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2019-51/segments/1575540508599.52/warc/CC-MAIN-20191208095535-20191208123535-00255.warc.gz"} |
https://www.physicsforums.com/threads/int-x-3-sin-x.166813/ | # Int x^3 sin x
1. Apr 21, 2007
### anderma8
I'm trying to integtrate x^3 sin x without using integration by parts. I have set up the equation to either:
int x^3 cosx dx = (Ax^3 + Bx^2+Cx+D)cos x + K
or
int x^3 coxs dx = (Ax^3+Bx)sinx + (Cx^2+D)cosx +K
but I'm having trouble... any help would be appreciated!
2. Apr 21, 2007
### AKG
Do you want to integrate x3sin(x) or x3cos(x)?
Why do you think you don't need a term involving sin here?
Why do you think the polynomial in front of sin doesn't need a square or constant term? Why do you think the polynomial in front of cos doesn't need a cube or linear term?
3. Apr 21, 2007
### anderma8
int x^3 cosx dx for this issue
essientially, we need to set this up and are having problems. We have an example of int x^4ex + dx. We get (Ax^4 + Bx^3 + Cx^2 + Ex +F) e^x + k. But we are stuck for finding the starting equation for int x^3 cosx.
4. Apr 21, 2007
### Staff: Mentor
Differentiate and solve for the coefficients.
5. Apr 21, 2007
### anderma8
but it's setting up the initial equation that is our road block. We get x^4e^x + dx but not clear on the setting up of X^3 cosx + dx
6. Apr 21, 2007
### Pseudo Statistic
Save yourself the trouble and do integration by parts.
7. Apr 21, 2007
### anderma8
we would but we can't use that as per the project instructions X-) Any suggestions?
8. Apr 21, 2007
### Staff: Mentor
How in the world do you get that?
Do you know how to calculate
$$\frac{d}{dx}\left(\int x^3\,\sin x\, dx\right)$$
Hint: Its fundamental.
9. Apr 22, 2007
### VietDao29
You should note that once you differentiate xncos(x), you'll get:
(xncos(x))' = nxn - 1cos(x) - xnsin(x), i.e, you have both cos, and sin function on the right, and the highest power of the polynomial is still n.
If you differentiate xnsin(x), you'll get almost the same.
(xnsin(x))' = nxn - 1sin(x) + xncos(x)
Note that, if you differentiate xncos(x), the highest power polynomial will go with sin(x), and vice versa. Note the italic, and underlined part.
So, if you want to find a function, such that its derivative is x3cos(x) (note that the power of the polynomial term is 3, and is highest), the function should look something like:
f(x) = (Ax3 + Bx2 + Cx + D) sin(x) + (Ex2 + Fx + G) cos(x)
Now, if you try to integrate the function xncos(x) by Parts, like this:
$$\int x ^ n \fbox{\cos x} dx = x ^ {n} \fbox{\sin x} - n \int x ^ {n - 1} \sin (x) dx$$
$$= x ^ {n} \fbox{\sin x} + n x ^ {n - 1} \cos(x) - n (n - 1) \int x ^ {n - 2} \cos (x) dx$$
$$= x ^ {n} \fbox{\sin x} + n x ^ {n - 1} \cos(x) - n (n - 1) x ^ {n - 2} \sin (x) + n (n - 1) (n - 2)\int x ^ {n - 3} \sin (x) dx = ...$$
So, you can see that the result will look something like xn sin(x) + n xn - 1 cos(x) - n (n - 1) xn - 2 sin(x) + ... i.e, one sin, and then one cos, and then back to one sin, and...
So, you can conclude that the constants B, D, and F in the function f(x) should all be 0, leaving you with:
f(x) = (Ax3 + Cx) sin(x) + (Ex2 + G) cos(x)
Can you get it? :)
Last edited: Apr 22, 2007
10. Apr 22, 2007
### AKG
Note that it doesn't hurt to have a little overkill. When I saw this problem, I differentiated:
(Ax4+Bx3+Cx2+Dx+E)sin(x) + (Fx4+Gx3+Hx2+Ix+J)cos(x)
Even though there are a lot of extra terms, differentiating polynomials and trigonometric functions is easy, and determining these undetermined coefficients ends up being very quick and easy.
11. Apr 22, 2007
### anderma8
VietDao29 - THANKS! Your explanation is very clear and was exactly the insight my team needed. We ended up doing just what you suggested before reading your post. The good thing is that we feel confident that we did the project correctly and with your input, it validated our work!
The interesting part is that we too noticed that the highest exponent went with the opposite trig funciton being integrated. Again, thanks for your reply!
12. Apr 22, 2007
### anderma8
AKG - After we tried the problem over and over, when we got what we were expecting, you are exactly right! It was funny, when my team started this, we were apprehensive at best, but now we look at them and laugh 'cause they really are easy when you understand the problem!
Thanks! | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 1, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.8281447887420654, "perplexity": 2051.8337804906296}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2016-44/segments/1476988719079.39/warc/CC-MAIN-20161020183839-00557-ip-10-171-6-4.ec2.internal.warc.gz"} |
https://www.gradesaver.com/textbooks/science/physics/essential-university-physics-volume-1-3rd-edition/chapter-9-exercises-and-problems-page-164/43 | ## Essential University Physics: Volume 1 (3rd Edition)
$(0,\frac{h}{4})$
We follow the book's advice to integrate the mass element over dy. Using the volume equation as well as the density, $\rho$, we find: $M = \int_0^h \frac{\pi r^2 \rho}{h^2} y^2dy$ $M = \frac{\pi r^2 \rho h^3}{3h^2}$ $M = \frac{\pi r^2 \rho h}{3}$ Using the integral equation for the center of mass and plugging in the above value for M, we find that the y center of mass is: $y_{cm} = \frac{h}{4}$ We know that the shape is symmetrical around the center in terms of x, so we find that the x center of mass is 0. | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 1, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.972634494304657, "perplexity": 207.585345282809}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2018-30/segments/1531676590295.61/warc/CC-MAIN-20180718154631-20180718174631-00286.warc.gz"} |
http://www.physicsforums.com/showthread.php?t=243092 | # Convert equation from cartesian to spherical
by glog
Tags: cartesian, convert, equation, spherical
P: 18 This should be relitively simple: y = x ... convert to spherical coords: p*sin(r)*sin(t) = p*sin(r)*cos(t) which reduces to... sin(t) = cos(t) tan(t) = 1 (is this right?) t =~ 0.78... (Can i get a nice fraction for this?) Any help is appreciated. - glog
P: 1,295 Looks good to me. pi/4 you simply substitute and simplify.
Math Emeritus Sci Advisor Thanks PF Gold P: 38,707 in other words, "y= x" in spherical coordinates reduces to the set of points where t= $\theta= \pi/4$, r= $\phi$ and p= $\rho$ can be anything. Do you see that that is, in fact, the same as the plane y= x?
P: 18
## Convert equation from cartesian to spherical
yep makes perfect sense....
only one angle is fixed :)
Related Discussions Calculus & Beyond Homework 6 Calculus & Beyond Homework 5 Differential Geometry 3 Precalculus Mathematics Homework 5 Calculus 4 | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 1, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.9104040265083313, "perplexity": 3953.628132204021}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2014-10/segments/1394011070356/warc/CC-MAIN-20140305091750-00012-ip-10-183-142-35.ec2.internal.warc.gz"} |
https://hackage.haskell.org/package/uniqueness-periods-vector-filters | # uniqueness-periods-vector-filters: A library allows to change the structure of the 'RealFrac' function output.
[ data, game, language, library, math, mit, uniqueness-periods ] [ Propose Tags ]
A library allows to change the structure of the RealFrac function output. At the moment only the equal intervals are supported.
## Modules
[Index] [Quick Jump] | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 1, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.37434548139572144, "perplexity": 10437.011797330524}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.3, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2022-49/segments/1669446710968.29/warc/CC-MAIN-20221204072040-20221204102040-00435.warc.gz"} |
http://math.stackexchange.com/questions/39944/algorithm-to-find-the-exact-roots-of-solvable-high-order-polynomials/39947 | # Algorithm to find the exact roots of solvable high-order polynomials?
It is not generally possible to determine the roots of a polynomial whose grade is bigger than 4 in terms of roots and basic operations. But I heard that it is possible to give a criteria whether a polynomial has such a solution.
For instance Wikipedia tells that the roots of a polynomial of degree $5$ are expressible in terms of roots and basic operations, if it is representable in the form
$$x^5 + \frac{5\mu^4(4\nu + 3)}{\nu^2 + 1}x + \frac{4\mu^5(2\nu + 1)(4\nu + 3)}{\nu^2 + 1} = 0,$$
where $\mu$ and $\nu$ are rational numbers.
Given the case that the polynomials roots are expressible in such a form, is it possible to give an algorithm that computes the solution in this form?
I am not an expert on that topic, just a student who is interested in maths.
-
Are you asking the same thing that was asked in math.stackexchange.com/questions/33612/how-to-solve-polynomials ? You may want to have a look at that question... – Steven Stadnicki May 18 '11 at 21:39
Yes, it's called Galois Theory.
-
I read the article and think, that you can certainly show that a polynomial's roots are describable in terms of radicands using the Galois Theory, but it doesn't explains you how to find them. – FUZxxl May 18 '11 at 20:48
@FUZxxl, see for instance math.stackexchange.com/questions/27877/… – lhf May 18 '11 at 21:41
While one cannot express the terms of polynomials of degree 5 and higher with basic operations and roots (Abel-Ruffini), it is possible to explicitly calculate the roots of polynomials of degree five and higher if you use other tools.
See this MO question.
-
My question was, if the polynomial is expressable in terms of radicals, is it possible to give an algorithm to find them? – FUZxxl May 19 '11 at 7:00
Yes, assuming an expression for a root exists, there is a simple algorithm that will find it: define an ordering on all such expressions (e.g. a lexical ordering), and test each one until you find a root of the input polynomial.
-
On the other hand, the problem of deciding whether a particular expression is a root of the given polynomial may not be so easy. I presume that it can be done numerically using some super-exponential error bound in terms of the length of the expression resulting from substituting the candidate root into the polynomial. Or is it guaranteed that it will evaluate to 0 symbolically? I'm really not sure. – Dan Brumleve Jun 2 '11 at 1:24
I'm pretty well convinced now that a symbolic method will work for the test, essentially because of algebraic independence (e.g. the cube root of p will never equal the square root of q). If anyone knows otherwise, I welcome a correction. – Dan Brumleve Jun 2 '11 at 1:40 | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 1, "mathjax_display_tex": 1, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.7382299304008484, "perplexity": 206.77981463761398}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 20, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2016-30/segments/1469257824201.56/warc/CC-MAIN-20160723071024-00204-ip-10-185-27-174.ec2.internal.warc.gz"} |
https://www.aimsciences.org/article/doi/10.3934/jimo.2021059?viewType=html | # American Institute of Mathematical Sciences
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May 2022, 18(3): 2109-2128. doi: 10.3934/jimo.2021059
## Stereo visual odometry based on dynamic and static features division
College of Missile Engineering, Rocket Force University of Engineering, Xi'an, Shaanxi 710025, China
* Corresponding author: Guangbin Cai
Received June 2020 Revised December 2020 Published May 2022 Early access March 2021
Fund Project: The first author is mainly supported by NSSF of China under Grant (No. 61773387)
Accurate camera pose estimation in dynamic scenes is an important challenge for visual simultaneous localization and mapping, and it is critical to reduce the effects of moving objects on pose estimation. To tackle this problem, a robust visual odometry approach in dynamic scenes is proposed, which can precisely distinguish between dynamic and static features. The key to the proposed method is combining the scene flow and the static features relative spatial distance invariance principle. Moreover, a new threshold is proposed to distinguish dynamic features.Then the dynamic features are eliminated after matching with the virtual map points. In addition, a new similarity calculation function is proposed to improve the performance of loop-closure detection. Finally, the camera pose is optimized after obtaining a closed loop. Experiments have been conducted on TUM datasets and actual scenes, which shows that the proposed method reduces tracking errors significantly and estimates the camera pose precisely in dynamic scenes.
Citation: Hui Xu, Guangbin Cai, Xiaogang Yang, Erliang Yao, Xiaofeng Li. Stereo visual odometry based on dynamic and static features division. Journal of Industrial and Management Optimization, 2022, 18 (3) : 2109-2128. doi: 10.3934/jimo.2021059
##### References:
[1] P. F. Alcantarilla, J. J. Yebes, J. Almazán et. al., On combining visual slam and dense scene flow to increase the robustness of localization and mapping in dynamic environments, 2012 IEEE International Conference on Robotics and Automation, Saint Paul, Minnesota, USA, IEEE, 2012. [2] Y. An, B. Li and L. Wang, Calibration of a 3D laser rangefinder and a camera based on optimization solution, J. Ind. Manag. Optim., 17 (2021), 427-445. doi: 10.3934/jimo.2019119. [3] A. Angeli, D. Filliat and S. Doncieux, Fast and incremental method for loop-closure detection using bags of visual words, IEEE Transactions on Robotics, 24 (2008), 1027-1037. [4] C. Bibby and I. Reid, Simultaneous localisation and mapping in dynamic environments (SLAMIDE) with reversible data association, Robotics: Science and Systems, Atlanta, Georgia, USA, 2007. [5] L. Bose and A. Richards, Fast Depth Edge Detection and Edge Based Rgb-D Slam, IEEE International Conference on Robotics and Automation, Stockholm, Sweden, IEEE, 2016. [6] C. Cadena, L. Carlone and H. Carrillo, Simultaneous localization and mapping: Present, future, and the robust-perception age, IEEE Transactions on Robotics, 32 (2016), 1309-1332. [7] C. Choi, A. J. Trevor and H. I. Christensen, Rgbd Edge Detection and Edge-Based Registration, 2013 IEEE/RSJ International Conference on Intelligent Robots and Systems, Tokyo, Japan, IEEE, 2013. [8] A. J. Davison, I. D. Reid and N. D. Molton, MonoSLAM: Real-time single camera SLAM, IEEE Transactions on Pattern Analysis & Machine Intelligence, 29 (2007), 1052-1067. [9] J. Engel, V. Koltun and D. Cremers, Direct sparse odometry, IEEE Transactions on Pattern Analysis & Machine Intelligence, 40 (2018), 611-625. [10] J. Engel, T. Schöps and D. Cremers, LSD-SLAM: Large-Scale Direct Monocular SLAM, European Conference on Computer Vision, Springer, Zürich, Switzerland, 2014. [11] J. Fan, On the Levenberg-Marquardt methods for convex constrained nonlinear equations, J. Ind. Manag. Optim., 9 (2013), 227-241. doi: 10.3934/jimo.2013.9.227. [12] C. Forster, M. Pizzoli and D Scaramuzza, SVO: Fast Semi-Direct Monocular Visual Odometry, IEEE International Conference on Robotics and Automation, Hong Kong, China, IEEE, 2014. [13] C. Forster, Z. Zhang and M. Gassner, SVO: Semi-direct visual odometry for monocular and multicamera systems, IEEE Transactions on Robotics, 33 (2017), 249-265. [14] J. Fuentes-Pacheo, J. Ruiz-Ascencio and J. M. Rendón-Mancha, Visual simultaneous localization and mapping: A survey, Artificial Intelligence Review, 43 (2015), 55-81. [15] D.-K. Gu, G.-P. Liu and G.-R. Duan, Robust stability of uncertain second-order linear time-varying systems, J. Franklin Inst., 356 (2019), 9881-9906. doi: 10.1016/j.jfranklin.2019.09.014. [16] D.-K. Gu and D.-W. Zhang, Parametric control to second-order linear time-varying systems based on dynamic compensator and multi-objective optimization, Appl. Math. Comput., 365 (2020), 124681, 25 pp. doi: 10.1016/j.amc.2019.124681. [17] D. K. Gu and D. W. Zhang, A parametric method to design dynamic compensator for high-order quasi-linear systems, Nonlinear Dynamics, 100 (2020), 1379-1400. [18] C. Kerl, J. Sturm and D. Cremers, Dense Visual Slam for Rgb-D Cameras, 2013 IEEE/RSJ International Conference on Intelligent Robots and Systems, Tokyo, Japan, IEEE, 2013. [19] D. H. Kim and J. H. Kim, Image-Based Icp Algorithm for Visual Odometry using a Rgb-D Sensor in a Dynamic Environment, Robot Intelligence Technology and Applications, Gwangju, Korea, Springer, 2013. [20] D. H. Kim, S. B. Han and J. H. Kim, Visual Odometry Algorithm using an Rgb-D Sensor and Imu in a Highly Dynamic Environment, Robot Intelligence Technology and Applications, Beijing, China, Springer, 2015. [21] D. H. Kim and J. H. Kim, Effective background model-based rgb-d dense visual odometry in a dynamic environment, IEEE Transactions on Robotics, 32 (2016), 1565-1573. [22] M. Labbe and F. Michaud, Appearance-based loop closure detection for online large-scale and long-term operation, IEEE Transactions on Robotics, 9 (2013), 734-745. [23] S. Li and D. Lee, Rgb-d slam in dynamic environments using static point weighting, IEEE Robotics and Automation Letters, 2 (2017), 2263-2270. [24] B. Li, D. Yang and L. Deng, Visual vocabulary tree with pyramid TF-IDF scoring match scheme for loop closure detection, Acta Automatica Sinica, 37 (2011), 665-673. [25] Y. Li, G. Zhang and F. Wang, An improved loop closure detection algorithm based on historical model set, Robot, 37 (2015), 663-673. [26] Z. L. Lin, G. L. Zhang and E. Yao, Sterero visual odometry based on motion object detection in the dynamic scene, Acta Optica Sinica, 37 (2017), 187-195. [27] M. Lourakis and X. Zabulis, Model-Based Pose Estimation for Rigid Objects, International conference on computer vision systems, St. Petersburg, Russia, Springer, 2013. [28] R. Mur-Artal, J. M. M. Montiel and J. D. Tardós, ORB-SLAM: A versatile and accurate monocular slam system, IEEE Transactions on Robotics, 31 (2015), 1147-1163. [29] R. Mur-Artal and J. D. Tardós, ORB-SLAM2: An opensource slam system for monocular, stereo, and rgbd cameras, IEEE Transactions on Robotics, 335 (2017), 1255-1262. [30] D. Nistér, O. Naroditsky and J. Bergen, Visual odometry for ground vehicle applications, Journal of Field Robotics, 23 (2006), 3-20. [31] Z. Peng, Research on Vision-Based Ego-Motion Estimation and Environment Modeling in Dynamic Environment, Ph.D. dissertation, Zhejiang University, Hangzhou, China, 2013. [32] D. Scaramuzza and F. Fraundorfer, Visual odometry, IEEE Robotics & Automation Magazine, 18 (2011), 80-92. [33] J. Sturm, N. Engelhard, F. Endres et. al., A Benchmark for the Evaluation of RGB-D SLAM Systems, IEEE International Conference on Intelligent Robots and Systems, Vilamoura, Portugal, IEEE, 2012. [34] Y. Sun, M. Liu and M. Q. H. Meng, Improving rgbd slam in dynamic environments: A motion removal approach, Robotics and Autonomous Systems, 89 (2017), 110-122. [35] W. Tan, H. Liu, Z. Dong et. al., Robust Monocular SLAM in Dynamic Environments, IEEE International Symposium on Mixed and Augmented Reality, Adelaide, Australia, IEEE, 2013. [36] G. Younes, D. Asmar and E. Shammas, Keyframe-based monocular slam: Design, survey, and future directions, Robotics and Autonomous Systems, 98 (2017), 67-88.
show all references
##### References:
[1] P. F. Alcantarilla, J. J. Yebes, J. Almazán et. al., On combining visual slam and dense scene flow to increase the robustness of localization and mapping in dynamic environments, 2012 IEEE International Conference on Robotics and Automation, Saint Paul, Minnesota, USA, IEEE, 2012. [2] Y. An, B. Li and L. Wang, Calibration of a 3D laser rangefinder and a camera based on optimization solution, J. Ind. Manag. Optim., 17 (2021), 427-445. doi: 10.3934/jimo.2019119. [3] A. Angeli, D. Filliat and S. Doncieux, Fast and incremental method for loop-closure detection using bags of visual words, IEEE Transactions on Robotics, 24 (2008), 1027-1037. [4] C. Bibby and I. Reid, Simultaneous localisation and mapping in dynamic environments (SLAMIDE) with reversible data association, Robotics: Science and Systems, Atlanta, Georgia, USA, 2007. [5] L. Bose and A. Richards, Fast Depth Edge Detection and Edge Based Rgb-D Slam, IEEE International Conference on Robotics and Automation, Stockholm, Sweden, IEEE, 2016. [6] C. Cadena, L. Carlone and H. Carrillo, Simultaneous localization and mapping: Present, future, and the robust-perception age, IEEE Transactions on Robotics, 32 (2016), 1309-1332. [7] C. Choi, A. J. Trevor and H. I. Christensen, Rgbd Edge Detection and Edge-Based Registration, 2013 IEEE/RSJ International Conference on Intelligent Robots and Systems, Tokyo, Japan, IEEE, 2013. [8] A. J. Davison, I. D. Reid and N. D. Molton, MonoSLAM: Real-time single camera SLAM, IEEE Transactions on Pattern Analysis & Machine Intelligence, 29 (2007), 1052-1067. [9] J. Engel, V. Koltun and D. Cremers, Direct sparse odometry, IEEE Transactions on Pattern Analysis & Machine Intelligence, 40 (2018), 611-625. [10] J. Engel, T. Schöps and D. Cremers, LSD-SLAM: Large-Scale Direct Monocular SLAM, European Conference on Computer Vision, Springer, Zürich, Switzerland, 2014. [11] J. Fan, On the Levenberg-Marquardt methods for convex constrained nonlinear equations, J. Ind. Manag. Optim., 9 (2013), 227-241. doi: 10.3934/jimo.2013.9.227. [12] C. Forster, M. Pizzoli and D Scaramuzza, SVO: Fast Semi-Direct Monocular Visual Odometry, IEEE International Conference on Robotics and Automation, Hong Kong, China, IEEE, 2014. [13] C. Forster, Z. Zhang and M. Gassner, SVO: Semi-direct visual odometry for monocular and multicamera systems, IEEE Transactions on Robotics, 33 (2017), 249-265. [14] J. Fuentes-Pacheo, J. Ruiz-Ascencio and J. M. Rendón-Mancha, Visual simultaneous localization and mapping: A survey, Artificial Intelligence Review, 43 (2015), 55-81. [15] D.-K. Gu, G.-P. Liu and G.-R. Duan, Robust stability of uncertain second-order linear time-varying systems, J. Franklin Inst., 356 (2019), 9881-9906. doi: 10.1016/j.jfranklin.2019.09.014. [16] D.-K. Gu and D.-W. Zhang, Parametric control to second-order linear time-varying systems based on dynamic compensator and multi-objective optimization, Appl. Math. Comput., 365 (2020), 124681, 25 pp. doi: 10.1016/j.amc.2019.124681. [17] D. K. Gu and D. W. Zhang, A parametric method to design dynamic compensator for high-order quasi-linear systems, Nonlinear Dynamics, 100 (2020), 1379-1400. [18] C. Kerl, J. Sturm and D. Cremers, Dense Visual Slam for Rgb-D Cameras, 2013 IEEE/RSJ International Conference on Intelligent Robots and Systems, Tokyo, Japan, IEEE, 2013. [19] D. H. Kim and J. H. Kim, Image-Based Icp Algorithm for Visual Odometry using a Rgb-D Sensor in a Dynamic Environment, Robot Intelligence Technology and Applications, Gwangju, Korea, Springer, 2013. [20] D. H. Kim, S. B. Han and J. H. Kim, Visual Odometry Algorithm using an Rgb-D Sensor and Imu in a Highly Dynamic Environment, Robot Intelligence Technology and Applications, Beijing, China, Springer, 2015. [21] D. H. Kim and J. H. Kim, Effective background model-based rgb-d dense visual odometry in a dynamic environment, IEEE Transactions on Robotics, 32 (2016), 1565-1573. [22] M. Labbe and F. Michaud, Appearance-based loop closure detection for online large-scale and long-term operation, IEEE Transactions on Robotics, 9 (2013), 734-745. [23] S. Li and D. Lee, Rgb-d slam in dynamic environments using static point weighting, IEEE Robotics and Automation Letters, 2 (2017), 2263-2270. [24] B. Li, D. Yang and L. Deng, Visual vocabulary tree with pyramid TF-IDF scoring match scheme for loop closure detection, Acta Automatica Sinica, 37 (2011), 665-673. [25] Y. Li, G. Zhang and F. Wang, An improved loop closure detection algorithm based on historical model set, Robot, 37 (2015), 663-673. [26] Z. L. Lin, G. L. Zhang and E. Yao, Sterero visual odometry based on motion object detection in the dynamic scene, Acta Optica Sinica, 37 (2017), 187-195. [27] M. Lourakis and X. Zabulis, Model-Based Pose Estimation for Rigid Objects, International conference on computer vision systems, St. Petersburg, Russia, Springer, 2013. [28] R. Mur-Artal, J. M. M. Montiel and J. D. Tardós, ORB-SLAM: A versatile and accurate monocular slam system, IEEE Transactions on Robotics, 31 (2015), 1147-1163. [29] R. Mur-Artal and J. D. Tardós, ORB-SLAM2: An opensource slam system for monocular, stereo, and rgbd cameras, IEEE Transactions on Robotics, 335 (2017), 1255-1262. [30] D. Nistér, O. Naroditsky and J. Bergen, Visual odometry for ground vehicle applications, Journal of Field Robotics, 23 (2006), 3-20. [31] Z. Peng, Research on Vision-Based Ego-Motion Estimation and Environment Modeling in Dynamic Environment, Ph.D. dissertation, Zhejiang University, Hangzhou, China, 2013. [32] D. Scaramuzza and F. Fraundorfer, Visual odometry, IEEE Robotics & Automation Magazine, 18 (2011), 80-92. [33] J. Sturm, N. Engelhard, F. Endres et. al., A Benchmark for the Evaluation of RGB-D SLAM Systems, IEEE International Conference on Intelligent Robots and Systems, Vilamoura, Portugal, IEEE, 2012. [34] Y. Sun, M. Liu and M. Q. H. Meng, Improving rgbd slam in dynamic environments: A motion removal approach, Robotics and Autonomous Systems, 89 (2017), 110-122. [35] W. Tan, H. Liu, Z. Dong et. al., Robust Monocular SLAM in Dynamic Environments, IEEE International Symposium on Mixed and Augmented Reality, Adelaide, Australia, IEEE, 2013. [36] G. Younes, D. Asmar and E. Shammas, Keyframe-based monocular slam: Design, survey, and future directions, Robotics and Autonomous Systems, 98 (2017), 67-88.
Stereo camera model
Generation of a visual vocabulary tree
Overview of the proposed algorithm in dynamic scenes
Classification of the scene flow based on angles [26]
Invariance of the relative spatial distance of the static points
Construction of the virtual map points
Three static features selected by the algorithm
Dynamic features obtained by the algorithm
Experiment scene sets
Experimental results of ORB-VO in lab scenes
Experimental results of the proposed method in lab scenes
Loop-closure detection result of the inverse proportional function
Loop-closure detection result of the negative exponential power function
Loop-closure detection result of the negative exponential power function
Comparisons between estimated trajectories and the ground truth in walking sequences
Comparisons between estimated trajectories and the ground truth in sitting sequences
Translation drift and rotational drift of VO method on TUM dataset
Sequences RMSE of translational drift [m/s] RMSE of rotational drift [$^{\circ}$/s] DVO BaMVO SPW-VO Our Method DVO BaMVO SPW-VO Our Method sitting-static 0.0157 0.0248 0.0231 0.0112 0.6084 0.6977 0.7228 0.3356 sitting-xyz 0.0453 0.0482 0.0219 0.0132 1.4980 1.3885 0.8466 0.5753 sitting-rpy 0.1735 0.1872 0.0843 0.0280 6.0164 5.9834 5.6258 0.6811 sitting-halfsphere 0.1005 0.0589 0.0389 0.0151 4.6490 2.8804 1.8836 0.6103 walking-static 0.3818 0.1339 0.0327 0.0293 6.3502 2.0833 0.8085 0.5500 walking-xyz 0.4360 0.2326 0.0651 0.1034 7.6669 4.3911 1.6442 2.3273 walking-rpy 0.4038 0.3584 0.2252 0.2143 7.0662 6.3898 5.6902 3.9555 walking-halfsphere 0.2628 0.1738 0.0527 0.1061 5.2179 4.2863 2.4048 2.2983
Sequences RMSE of translational drift [m/s] RMSE of rotational drift [$^{\circ}$/s] DVO BaMVO SPW-VO Our Method DVO BaMVO SPW-VO Our Method sitting-static 0.0157 0.0248 0.0231 0.0112 0.6084 0.6977 0.7228 0.3356 sitting-xyz 0.0453 0.0482 0.0219 0.0132 1.4980 1.3885 0.8466 0.5753 sitting-rpy 0.1735 0.1872 0.0843 0.0280 6.0164 5.9834 5.6258 0.6811 sitting-halfsphere 0.1005 0.0589 0.0389 0.0151 4.6490 2.8804 1.8836 0.6103 walking-static 0.3818 0.1339 0.0327 0.0293 6.3502 2.0833 0.8085 0.5500 walking-xyz 0.4360 0.2326 0.0651 0.1034 7.6669 4.3911 1.6442 2.3273 walking-rpy 0.4038 0.3584 0.2252 0.2143 7.0662 6.3898 5.6902 3.9555 walking-halfsphere 0.2628 0.1738 0.0527 0.1061 5.2179 4.2863 2.4048 2.2983
RMSE of the ATE of camera pose estimation (m$^{-1}$)
Sequences ORB-SLAM2 MR-SLAM SPW-SLAM SF-SLAM Our Method sitting-static 0.0082 – – 0.0081 0.0073 sitting-xyz 0.0094 0.0482 0.0397 0.0101 0.0090 sitting-rpy 0.0197 – – 0.0180 0.0162 sitting-halfsphere 0.0211 0.0470 0.0432 0.0239 0.0164 walking-static 0.1028 0.0656 0.0261 0.0120 0.0108 walking-xyz 0.4278 0.0932 0.0601 0.2251 0.0884 walking-rpy 0.7407 0.1333 0.1791 0.1961 0.3620 walking-halfsphere 0.4939 0.1252 0.0489 0.0423 0.0411
Sequences ORB-SLAM2 MR-SLAM SPW-SLAM SF-SLAM Our Method sitting-static 0.0082 – – 0.0081 0.0073 sitting-xyz 0.0094 0.0482 0.0397 0.0101 0.0090 sitting-rpy 0.0197 – – 0.0180 0.0162 sitting-halfsphere 0.0211 0.0470 0.0432 0.0239 0.0164 walking-static 0.1028 0.0656 0.0261 0.0120 0.0108 walking-xyz 0.4278 0.0932 0.0601 0.2251 0.0884 walking-rpy 0.7407 0.1333 0.1791 0.1961 0.3620 walking-halfsphere 0.4939 0.1252 0.0489 0.0423 0.0411
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Albert Einstein (n.)
1.physicist born in Germany who formulated the special theory of relativity and the general theory of relativity; Einstein also proposed that light consists of discrete quantized bundles of energy (later called photons) (1879-1955)
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Albert Einstein (n.)
Einstein
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Albert Einstein (n.)
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physicien célèbre (fr)[Classe]
mathématicien. (fr)[ClasseParExt.]
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Albert Einstein (n.)
Wikipedia
Albert Einstein
Albert Einstein
Albert Einstein in 1921
Born 14 March 1879
Ulm, Kingdom of Württemberg, German Empire
Died 18 April 1955 (aged 76)
Princeton, New Jersey, United States
Residence Germany, Italy, Switzerland, Austria, Belgium, United Kingdom, United States
Citizenship
Fields Physics
Institutions
Alma mater
Notable students
Known for
Notable awards
Spouse Mileva Marić (1903–1919)
Elsa Löwenthal, née Einstein, (1919–1936)
Signature
Albert Einstein (; German: [ˈalbɐt ˈaɪnʃtaɪn] ( listen); 14 March 1879 – 18 April 1955) was a German theoretical physicist who developed the theory of general relativity, effecting a revolution in physics. For this achievement, Einstein is often regarded as the father of modern physics.[2][3] Einstein is generally considered the most influential physicist of the 20th century. While best known for his mass–energy equivalence formula E = mc2 (which has been dubbed "the world's most famous equation"),[4] he received the 1921 Nobel Prize in Physics "for his services to theoretical physics, and especially for his discovery of the law of the photoelectric effect".[5] The latter was pivotal in establishing quantum theory within physics.
Near the beginning of his career, Einstein thought that Newtonian mechanics was no longer enough to reconcile the laws of classical mechanics with the laws of the electromagnetic field. This led to the development of his special theory of relativity. He realized, however, that the principle of relativity could also be extended to gravitational fields, and with his subsequent theory of gravitation in 1916, he published a paper on the general theory of relativity. He continued to deal with problems of statistical mechanics and quantum theory, which led to his explanations of particle theory and the motion of molecules. He also investigated the thermal properties of light which laid the foundation of the photon theory of light. In 1917, Einstein applied the general theory of relativity to model the structure of the universe as a whole.[6]
He was visiting the United States when Adolf Hitler came to power in 1933, and did not go back to Germany, where he had been a professor at the Berlin Academy of Sciences. He settled in the U.S., becoming a citizen in 1940.[7] On the eve of World War II, he helped alert President Franklin D. Roosevelt that Germany might be developing an atomic weapon, and recommended that the U.S. begin similar research; this eventually led to what would become the Manhattan Project. Einstein was in support of defending the Allied forces, but largely denounced using the new discovery of nuclear fission as a weapon. Later, together with Bertrand Russell, Einstein signed the Russell–Einstein Manifesto, which highlighted the danger of nuclear weapons. Einstein was affiliated with the Institute for Advanced Study in Princeton, New Jersey, until his death in 1955.
Einstein published more than 300 scientific papers along with over 150 non-scientific works.[6][8] His great intelligence and originality have made the word "Einstein" synonymous with genius.[9]
Biography
Early life and education
Einstein at the age of three in 1882
Albert Einstein in 1893 (age 14)
Einstein's matriculation certificate at the age of 17, showing his final grades from the Aargau Kantonsschule (on a scale of 1-6).
Albert Einstein was born in Ulm, in the Kingdom of Württemberg in the German Empire on 14 March 1879.[10] His father was Hermann Einstein, a salesman and engineer. His mother was Pauline Einstein (née Koch). In 1880, the family moved to Munich, where his father and his uncle founded Elektrotechnische Fabrik J. Einstein & Cie, a company that manufactured electrical equipment based on direct current.[10]
The Einsteins were non-observant Jews. Albert attended a Catholic elementary school from the age of five for three years. Later, at the age of eight, Einstein was transferred to the Luitpold Gymnasium where he received advanced primary and secondary school education until he left Germany seven years later.[11] Although it has been thought that Einstein had early speech difficulties, this is disputed by the Albert Einstein Archives, and he excelled at the first school that he attended.[12]
His father once showed him a pocket compass; Einstein realized that there must be something causing the needle to move, despite the apparent "empty space".[13] As he grew, Einstein built models and mechanical devices for fun and began to show a talent for mathematics.[10] When Einstein was ten years old Max Talmud (later changed to Max Talmey), a poor Jewish medical student from Poland, was introduced to the Einstein family by his brother, and during weekly visits over the next five years he gave the boy popular books on science, mathematical texts and philosophical writings. These included Immanuel Kant's Critique of Pure Reason and Euclid's Elements (which Einstein called the "holy little geometry book").[14][15][fn 1]
In 1894, his father's company failed: direct current (DC) lost the War of Currents to alternating current (AC). In search of business, the Einstein family moved to Italy, first to Milan and then, a few months later, to Pavia. When the family moved to Pavia, Einstein stayed in Munich to finish his studies at the Luitpold Gymnasium. His father intended for him to pursue electrical engineering, but Einstein clashed with authorities and resented the school's regimen and teaching method. He later wrote that the spirit of learning and creative thought were lost in strict rote learning. At the end of December 1894 he travelled to Italy to join his family in Pavia, convincing the school to let him go by using a doctor's note.[17] It was during his time in Italy that he wrote a short essay with the title "On the Investigation of the State of the Ether in a Magnetic Field."[18][19]
In late summer 1895, at the age of sixteen, Einstein sat the entrance examinations for the Swiss Federal Polytechnic in Zurich (later the Eidgenössische Polytechnische Schule). He failed to reach the required standard in several subjects, but obtained exceptional grades in physics and mathematics.[20] On the advice of the Principal of the Polytechnic, he attended the Aargau Cantonal School in Aarau, Switzerland, in 1895-96 to complete his secondary schooling. While lodging with the family of Professor Jost Winteler, he fell in love with Winteler's daughter, Marie. (His sister Maja later married the Wintelers' son, Paul.)[21] In January 1896, with his father's approval, he renounced his citizenship in the German Kingdom of Württemberg to avoid military service.[22] In September 1896 he passed the Swiss Matura with mostly good grades (gaining maximum grade 6 in physics and mathematical subjects, on a scale 1-6),[23] and though still only seventeen he enrolled in the four year mathematics and physics teaching diploma program at the ETH Zurich. Marie Winteler moved to Olsberg, Switzerland for a teaching post.
Einstein's future wife, Mileva Marić, also enrolled at the Polytechnic that same year, the only woman among the six students in the mathematics and physics section of the teaching diploma course. Over the next few years, Einstein and Marić's friendship developed into romance, and they read books together on extra-curricular physics in which Einstein was taking an increasing interest. In 1900 Einstein was awarded the Zurich Polytechnic teaching diploma, but Marić failed the examination with a poor grade in the mathematics component, theory of functions.[24] There have been claims that Marić collaborated with Einstein on his celebrated 1905 papers,[25][26] but historians of physics who have studied the issue find no evidence that she made any substantive contributions.[27][28][29][30]
Marriages and children
In early 1902, Einstein and Mileva Marić (Милева Марић) had a daughter they named Lieserl in their correspondence, who was born in Novi Sad where Marić's parents lived.[31] Her full name is not known, and her fate is uncertain after 1903.[32]
Einstein and Marić married in January 1903. In May 1904, the couple's first son, Hans Albert Einstein, was born in Bern, Switzerland. Their second son, Eduard, was born in Zurich in July 1910. In 1914, Einstein moved to Berlin, while his wife remained in Zurich with their sons. Marić and Einstein divorced on 14 February 1919, having lived apart for five years.
Einstein married Elsa Löwenthal (née Einstein) on 2 June 1919, after having had a relationship with her since 1912. She was his first cousin maternally and his second cousin paternally. In 1933, they emigrated permanently to the United States. In 1935, Elsa Einstein was diagnosed with heart and kidney problems and died in December 1936.[33]
Patent office
Left to right: Conrad Habicht, Maurice Solovine and Einstein, who founded the Olympia Academy
Einstein's home in Bern
After graduating, Einstein spent almost two frustrating years searching for a teaching post, but a former classmate's father helped him secure a job in Bern, at the Federal Office for Intellectual Property, the patent office, as an assistant examiner.[34] He evaluated patent applications for electromagnetic devices. In 1903, Einstein's position at the Swiss Patent Office became permanent, although he was passed over for promotion until he "fully mastered machine technology".[35]
Much of his work at the patent office related to questions about transmission of electric signals and electrical-mechanical synchronization of time, two technical problems that show up conspicuously in the thought experiments that eventually led Einstein to his radical conclusions about the nature of light and the fundamental connection between space and time.[36]
With a few friends he met in Bern, Einstein started a small discussion group, self-mockingly named "The Olympia Academy", which met regularly to discuss science and philosophy. Their readings included the works of Henri Poincaré, Ernst Mach, and David Hume, which influenced his scientific and philosophical outlook.
Einstein's official 1921 portrait after receiving the Nobel Prize in Physics.
During 1901, the paper "Folgerungen aus den Kapillarität Erscheinungen" ("Conclusions from the Capillarity Phenomena") was published in the prestigious Annalen der Physik.[37] On 30 April 1905, Einstein completed his thesis, with Alfred Kleiner, Professor of Experimental Physics, serving as pro-forma advisor. Einstein was awarded a PhD by the University of Zurich. His dissertation was entitled "A New Determination of Molecular Dimensions".[38][39] That same year, which has been called Einstein's annus mirabilis (miracle year), he published four groundbreaking papers, on the photoelectric effect, Brownian motion, special relativity, and the equivalence of matter and energy, which were to bring him to the notice of the academic world.
By 1908, he was recognized as a leading scientist, and he was appointed lecturer at the University of Bern. The following year, he quit the patent office and the lectureship to take the position of physics docent [40] at the University of Zurich. He became a full professor at Karl-Ferdinand University in Prague in 1911. In 1914, he returned to Germany after being appointed director of the Kaiser Wilhelm Institute for Physics (1914–1932)[41] and a professor at the Humboldt University of Berlin, with a special clause in his contract that freed him from most teaching obligations. He became a member of the Prussian Academy of Sciences. In 1916, Einstein was appointed president of the German Physical Society (1916–1918).[42][43]
During 1911, he had calculated that, based on his new theory of general relativity, light from another star would be bent by the Sun's gravity. That prediction was claimed confirmed by observations made by a British expedition led by Sir Arthur Eddington during the solar eclipse of 29 May 1919. International media reports of this made Einstein world famous. On 7 November 1919, the leading British newspaper The Times printed a banner headline that read: "Revolution in Science – New Theory of the Universe – Newtonian Ideas Overthrown".[44] (Much later, questions were raised whether the measurements had been accurate enough to support Einstein's theory).
In 1921, Einstein was awarded the Nobel Prize in Physics for his explanation of the photoelectric effect, as relativity was considered still somewhat controversial. He also received the Copley Medal from the Royal Society in 1925.
Einstein visited New York City for the first time on 2 April 1921, where he received an official welcome by the Mayor, followed by three weeks of lectures and receptions. He went on to deliver several lectures at Columbia University and Princeton University, and in Washington he accompanied representatives of the National Academy of Science on a visit to the White House. On his return to Europe he was the guest of the British statesman and philosopher Viscount Haldane in London, where he met several renowned scientific, intellectual and political figures, and delivered a lecture at Kings College.[45]
In 1922, he traveled throughout Asia and later to Palestine, as part of a six-month excursion and speaking tour. His travels included Singapore, Ceylon, and Japan, where he gave a series of lectures to thousands of Japanese. His first lecture in Tokyo lasted four hours, after which he met the emperor and empress at the Imperial Palace where thousands came to watch. Einstein later gave his impressions of the Japanese in a letter to his sons:[46]:307 "Of all the people I have met, I like the Japanese most, as they are modest, intelligent, considerate, and have a feel for art."[46]:308
On his return voyage, he also visited Palestine for 12 days in what would become his only visit to that region. "He was greeted with great British pomp, as if he were a head of state rather than a theoretical physicist", writes Isaacson. This included a cannon salute upon his arrival at the residence of the British high commissioner, Sir Herbert Samuel. During one reception given to him, the building was "stormed by throngs who wanted to hear him". In Einstein's talk to the audience, he expressed his happiness over the event:
I consider this the greatest day of my life. Before, I have always found something to regret in the Jewish soul, and that is the forgetfulness of its own people. Today, I have been made happy by the sight of the Jewish people learning to recognize themselves and to make themselves recognized as a force in the world.[47]:308.
Love of music
Einstein developed an appreciation of music at an early age. His mother played the piano reasonably well and wanted her son to learn the violin, not only to instill in him a love of music but also to help him assimilate within German culture. According to conductor Leon Botstein, Einstein is said to have begun playing when he was five, but didn't enjoy trying to learn it at that age.[48]
When he turned thirteen, however, he discovered the violin sonatas of Mozart. "Einstein fell in love" with Mozart's music, notes Botstein, and learned to play music more willingly. According to Einstein, he taught himself to play by "ever practicing systematically," adding that "Love is a better teacher than a sense of duty."[48] At age seventeen, he was heard by a school examiner in Aarau as he played Beethoven's violin sonatas, the examiner stating afterward that his playing was "remarkable and revealing of 'great insight.'" What struck the examiner, writes Botstein, was that Einstein "displayed a deep love of the music, a quality that was and remains in short supply. Music possessed an unusual meaning for this student."[48]
Botstein notes that music assumed a pivotal and permanent role in Einstein's life from that period on. Although the idea of becoming a professional himself was not on his mind at any time, a few professionals were among those with whom Einstein played chamber music, and he performed for private audiences and friends. Chamber music also became a regular part of his social life while living in Bern, Zurich, and Berlin, where he played with Max Planck and his son, among others. In 1931, while engaged in research at California Institute of Technology, he visited the Zoellner family conservatory in Los Angeles and played music of Beethoven and Mozart with members of the Zoellner Quartet, recently retired from two decades of acclaimed touring all across the United States; Einstein later presented the family patriarch with an autographed photograph as a memento.[49] [50] Near the end of his life, while Einstein was living in Princeton, the young Juilliard Quartet visited him, and he joined them playing his violin; although they slowed the tempo to accommodate his lesser technical abilities, Botstein notes the quartet was "impressed by Einstein's level of coordination and intonation."[48]
Emigration
Cartoon of Einstein, who has shed his "Pacifism" wings, standing next to a pillar labeled "World Peace." He is rolling up his sleeves and holding a sword labeled "Preparedness" (circa 1933).
In 1933, Einstein decided to emigrate to the United States due to the rise to power of the Nazis under Germany's new chancellor, Adolf Hitler.[51] While visiting American universities in April, 1933, he learned that the new German government had passed a law barring Jews from holding any official positions, including teaching at universities. A month later, the Nazi book burnings occurred, with Einstein's works being among those burnt, and Nazi propaganda minister Joseph Goebbels proclaimed, "Jewish intellectualism is dead."[47] Einstein also learned that his name was on a list of assassination targets, with a "\$5,000 bounty on his head." One German magazine included him in a list of enemies of the German regime with the phrase, "not yet hanged".[47]
Einstein was undertaking his third two-month visiting professorship at the California Institute of Technology when Hitler came to power in Germany. On his return to Europe in March 1933 he resided in Belgium for some months, before temporarily moving to England.[52]
He took up a position at the Institute for Advanced Study at Princeton, New Jersey,[53] an affiliation that lasted until his death in 1955. He was one of the four first selected (two of the others being John von Neumann and Kurt Gödel). At the institute, he soon developed a close friendship with Gödel. The two would take long walks together discussing their work. His last assistant was Bruria Kaufman, who later became a renowned physicist. During this period, Einstein tried to develop a unified field theory and to refute the accepted interpretation of quantum physics, both unsuccessfully.
Other scientists also fled to America. Among them were Nobel laureates and professors of theoretical physics. With so many other Jewish scientists now forced by circumstances to live in America, often working side by side, Einstein wrote to a friend, "For me the most beautiful thing is to be in contact with a few fine Jews—a few millennia of a civilized past do mean something after all." In another letter he writes, "In my whole life I have never felt so Jewish as now."[47]
World War II and the Manhattan Project
In 1939, a group of Hungarian scientists that included emigre physicist Leó Szilárd attempted to alert Washington of ongoing Nazi atomic bomb research. The group's warnings were discounted.[54] Einstein and Szilárd, along with other refugees such as Edward Teller and Eugene Wigner, "regarded it as their responsibility to alert Americans to the possibility that German scientists might win the race to build an atomic bomb, and to warn that Hitler would be more than willing to resort to such a weapon."[46]:630[55] In the summer of 1939, a few months before the beginning of World War II in Europe, Einstein was persuaded to lend his prestige by writing a letter with Szilárd to President Franklin D. Roosevelt to alert him of the possibility. The letter also recommended that the U.S. government pay attention to and become directly involved in uranium research and associated chain reaction research.
The letter is believed to be "arguably the key stimulus for the U.S. adoption of serious investigations into nuclear weapons on the eve of the U.S. entry into World War II".[56] President Roosevelt could not take the risk of allowing Hitler to possess atomic bombs first. As a result of Einstein's letter and his meetings with Roosevelt, the U.S. entered the "race" to develop the bomb, drawing on its "immense material, financial, and scientific resources" to initiate the Manhattan Project. It became the only country to successfully develop an atomic bomb during World War II.
For Einstein, "war was a disease . . . [and] he called for resistance to war." But in 1933, after Hitler assumed full power in Germany, "he renounced pacifism altogether . . . In fact, he urged the Western powers to prepare themselves against another German onslaught."[57]:110 In 1954, a year before his death, Einstein said to his old friend, Linus Pauling, "I made one great mistake in my life — when I signed the letter to President Roosevelt recommending that atom bombs be made; but there was some justification — the danger that the Germans would make them..."[58]
U.S. citizenship
Accepting U.S. citizenship, 1940
Einstein became an American citizen in 1940. Not long after settling into his career at Princeton, he expressed his appreciation of the "meritocracy" in American culture when compared to Europe. According to Isaacson, he recognized the "right of individuals to say and think what they pleased", without social barriers, and as result, the individual was "encouraged" to be more creative, a trait he valued from his own early education. Einstein writes:
What makes the new arrival devoted to this country is the democratic trait among the people. No one humbles himself before another person or class. . . American youth has the good fortune not to have its outlook troubled by outworn traditions.[47]:432
As a member of the National Association for the Advancement of Colored People (NAACP) at Princeton who campaigned for the civil rights of African Americans, Einstein corresponded with civil rights activist W. E. B. Du Bois, and in 1946 Einstein called racism America's "worst disease".[59] He later stated, "Race prejudice has unfortunately become an American tradition which is uncritically handed down from one generation to the next. The only remedies are enlightenment and education".[60]
After the death of Israel's first president, Chaim Weizmann, in November 1952, Prime Minister David Ben-Gurion offered Einstein the position of President of Israel, a mostly ceremonial post.[61] The offer was presented by Israel's ambassador in Washington, Abba Eban, who explained that the offer "embodies the deepest respect which the Jewish people can repose in any of its sons".[46]:522 However, Einstein declined, and wrote in his response that he was "deeply moved", and "at once saddened and ashamed" that he could not accept it:
All my life I have dealt with objective matters, hence I lack both the natural aptitude and the experience to deal properly with people and to exercise official function. I am the more distressed over these circumstances because my relationship with the Jewish people became my strongest human tie once I achieved complete clarity about our precarious position among the nations of the world.[46]:522[61][62]
Death
The New York World-Telegram announces Einstein's death on 18 April 1955.
On 17 April 1955, Albert Einstein experienced internal bleeding caused by the rupture of an abdominal aortic aneurysm, which had previously been reinforced surgically by Dr. Rudolph Nissen in 1948.[63] He took the draft of a speech he was preparing for a television appearance commemorating the State of Israel's seventh anniversary with him to the hospital, but he did not live long enough to complete it.[64] Einstein refused surgery, saying: "I want to go when I want. It is tasteless to prolong life artificially. I have done my share, it is time to go. I will do it elegantly."[65] He died in Princeton Hospital early the next morning at the age of 76, having continued to work until near the end.
During the autopsy, the pathologist of Princeton Hospital, Thomas Stoltz Harvey, removed Einstein's brain for preservation without the permission of his family, in the hope that the neuroscience of the future would be able to discover what made Einstein so intelligent.[66] Einstein's remains were cremated and his ashes were scattered at an undisclosed location.[67][68]
In his lecture at Einstein's memorial, nuclear physicist Robert Oppenheimer summarized his impression of him as a person: "He was almost wholly without sophistication and wholly without worldliness . . . There was always with him a wonderful purity at once childlike and profoundly stubborn."[57]
Scientific career
Albert Einstein in 1904
The photoelectric effect. Incoming photons on the left strike a metal plate (bottom), and eject electrons, depicted as flying off to the right.
Throughout his life, Einstein published hundreds of books and articles.[8][10] In addition to the work he did by himself he also collaborated with other scientists on additional projects including the Bose–Einstein statistics, the Einstein refrigerator and others.[69]
1905 - Annus Mirabilis papers
The Annus Mirabilis papers are four articles pertaining to the photoelectric effect (which gave rise to quantum theory), Brownian motion, the special theory of relativity, and E = mc2 that Albert Einstein published in the Annalen der Physik scientific journal in 1905. These four works contributed substantially to the foundation of modern physics and changed views on space, time, and matter. The four papers are:
Title (translated) Area of focus Received Published Significance
On a Heuristic Viewpoint Concerning the Production and Transformation of Light Photoelectric effect 18 March 9 June Resolved an unsolved puzzle by suggesting that energy is exchanged only in discrete amounts (quanta).[70] This idea was pivotal to the early development of quantum theory.[71]
On the Motion of Small Particles Suspended in a Stationary Liquid, as Required by the Molecular Kinetic Theory of Heat Brownian motion 11 May 18 July Explained empirical evidence for the atomic theory, supporting the application of statistical physics.
On the Electrodynamics of Moving Bodies Special relativity 30 June 26 Sept Reconciled Maxwell's equations for electricity and magnetism with the laws of mechanics by introducing major changes to mechanics close to the speed of light, resulting from analysis based on empirical evidence that the speed of light is independent of the motion of the observer.[72] Discredited the concept of an "luminiferous ether."[73]
Does the Inertia of a Body Depend Upon Its Energy Content? Matter–energy equivalence 27 Sept 21 Nov Equivalence of matter and energy, E = mc2 (and by implication, the ability of gravity to "bend" light), the existence of "rest energy", and the basis of nuclear energy.
Thermodynamic fluctuations and statistical physics
Albert Einstein's first paper[74] submitted in 1900 to Annalen der Physik was on capillary attraction. It was published in 1901 with the title "Folgerungen aus den Kapillarität Erscheinungen," which translates as "Conclusions from the capillarity phenomena". Two papers he published in 1902–1903 (thermodynamics) attempted to interpret atomic phenomena from a statistical point of view. These papers were the foundation for the 1905 paper on Brownian motion, which showed that Brownian movement can be construed as firm evidence that molecules exist. His research in 1903 and 1904 was mainly concerned with the effect of finite atomic size on diffusion phenomena.[74]
General principles
He articulated the principle of relativity. This was understood by Hermann Minkowski to be a generalization of rotational invariance from space to space-time. Other principles postulated by Einstein and later vindicated are the principle of equivalence and the principle of adiabatic invariance of the quantum number.
Theory of relativity and $E = mc ^2$
Einstein's "Zur Elektrodynamik bewegter Körper" ("On the Electrodynamics of Moving Bodies") was received on 30 June 1905 and published 26 September of that same year. It reconciles Maxwell's equations for electricity and magnetism with the laws of mechanics, by introducing major changes to mechanics close to the speed of light. This later became known as Einstein's special theory of relativity.
Consequences of this include the time-space frame of a moving body appearing to slow down and contract (in the direction of motion) when measured in the frame of the observer. This paper also argued that the idea of a luminiferous aether – one of the leading theoretical entities in physics at the time – was superfluous.[75]
In his paper on mass–energy equivalence Einstein produced E = mc2 from his special relativity equations.[76] Einstein's 1905 work on relativity remained controversial for many years, but was accepted by leading physicists, starting with Max Planck.[77][78]
Photons and energy quanta
In a 1905 paper,[79] Einstein postulated that light itself consists of localized particles (quanta). Einstein's light quanta were nearly universally rejected by all physicists, including Max Planck and Niels Bohr. This idea only became universally accepted in 1919, with Robert Millikan's detailed experiments on the photoelectric effect, and with the measurement of Compton scattering.
Einstein concluded that each wave of frequency f is associated with a collection of photons with energy hf each, where h is Planck's constant. He does not say much more, because he is not sure how the particles are related to the wave. But he does suggest that this idea would explain certain experimental results, notably the photoelectric effect.[80]
Quantized atomic vibrations
In 1907 Einstein proposed a model of matter where each atom in a lattice structure is an independent harmonic oscillator. In the Einstein model, each atom oscillates independently – a series of equally spaced quantized states for each oscillator. Einstein was aware that getting the frequency of the actual oscillations would be different, but he nevertheless proposed this theory because it was a particularly clear demonstration that quantum mechanics could solve the specific heat problem in classical mechanics. Peter Debye refined this model.[81]
Throughout the 1910s, quantum mechanics expanded in scope to cover many different systems. After Ernest Rutherford discovered the nucleus and proposed that electrons orbit like planets, Niels Bohr was able to show that the same quantum mechanical postulates introduced by Planck and developed by Einstein would explain the discrete motion of electrons in atoms, and the periodic table of the elements.
Einstein contributed to these developments by linking them with the 1898 arguments Wilhelm Wien had made. Wien had shown that the hypothesis of adiabatic invariance of a thermal equilibrium state allows all the blackbody curves at different temperature to be derived from one another by a simple shifting process. Einstein noted in 1911 that the same adiabatic principle shows that the quantity which is quantized in any mechanical motion must be an adiabatic invariant. Arnold Sommerfeld identified this adiabatic invariant as the action variable of classical mechanics. The law that the action variable is quantized was a basic principle of the quantum theory as it was known between 1900 and 1925.[citation needed]
Wave–particle duality
Einstein at the Solvay Conference in 1911
Although the patent office promoted Einstein to Technical Examiner Second Class in 1906, he had not given up on academia. In 1908, he became a privatdozent at the University of Bern.[82] In "über die Entwicklung unserer Anschauungen über das Wesen und die Konstitution der Strahlung" ("The Development of Our Views on the Composition and Essence of Radiation"), on the quantization of light, and in an earlier 1909 paper, Einstein showed that Max Planck's energy quanta must have well-defined momenta and act in some respects as independent, point-like particles. This paper introduced the photon concept (although the name photon was introduced later by Gilbert N. Lewis in 1926) and inspired the notion of wave–particle duality in quantum mechanics.
Theory of critical opalescence
Einstein returned to the problem of thermodynamic fluctuations, giving a treatment of the density variations in a fluid at its critical point. Ordinarily the density fluctuations are controlled by the second derivative of the free energy with respect to the density. At the critical point, this derivative is zero, leading to large fluctuations. The effect of density fluctuations is that light of all wavelengths is scattered, making the fluid look milky white. Einstein relates this to Raleigh scattering, which is what happens when the fluctuation size is much smaller than the wavelength, and which explains why the sky is blue.[83] Einstein quantitatively derived critical opalescence from a treatment of density fluctuations, and demonstrated how both the effect and Rayleigh scattering originate from the atomistic constitution of matter.
Zero-point energy
Einstein's physical intuition led him to note that Planck's oscillator energies had an incorrect zero point. He modified Planck's hypothesis by stating that the lowest energy state of an oscillator is equal to 12hf, to half the energy spacing between levels. This argument, which was made in 1913 in collaboration with Otto Stern, was based on the thermodynamics of a diatomic molecule which can split apart into two free atoms.
General relativity and the Equivalence Principle
Eddington’s photograph of a solar eclipse.
General relativity (GR) is a theory of gravitation that was developed by Albert Einstein between 1907 and 1915. According to general relativity, the observed gravitational attraction between masses results from the warping of space and time by those masses. General relativity has developed into an essential tool in modern astrophysics. It provides the foundation for the current understanding of black holes, regions of space where gravitational attraction is so strong that not even light can escape.
As Albert Einstein later said, the reason for the development of general relativity was that the preference of inertial motions within special relativity was unsatisfactory, while a theory which from the outset prefers no state of motion (even accelerated ones) should appear more satisfactory.[84] So in 1908 he published an article on acceleration under special relativity. In that article, he argued that free fall is really inertial motion, and that for a freefalling observer the rules of special relativity must apply. This argument is called the Equivalence principle. In the same article, Einstein also predicted the phenomenon of gravitational time dilation. In 1911, Einstein published another article expanding on the 1907 article, in which additional effects such as the deflection of light by massive bodies were predicted.
Hole argument and Entwurf theory
While developing general relativity, Einstein became confused about the gauge invariance in the theory. He formulated an argument that led him to conclude that a general relativistic field theory is impossible. He gave up looking for fully generally covariant tensor equations, and searched for equations that would be invariant under general linear transformations only.
In June, 1913 the Entwurf ("draft") theory was the result of these investigations. As its name suggests, it was a sketch of a theory, with the equations of motion supplemented by additional gauge fixing conditions. Simultaneously less elegant and more difficult than general relativity, after more than two years of intensive work Einstein abandoned the theory in November, 1915 after realizing that the hole argument was mistaken.[85]
Cosmology
In 1917, Einstein applied the General theory of relativity to model the structure of the universe as a whole. He wanted the universe to be eternal and unchanging, but this type of universe is not consistent with relativity. To fix this, Einstein modified the general theory by introducing a new notion, the cosmological constant. With a positive cosmological constant, the universe could be an eternal static sphere.[86]
Einstein in his office at the University of Berlin.
Einstein believed a spherical static universe is philosophically preferred, because it would obey Mach's principle. He had shown that general relativity incorporates Mach's principle to a certain extent in frame dragging by gravitomagnetic fields, but he knew that Mach's idea would not work if space goes on forever. In a closed universe, he believed that Mach's principle would hold. Mach's principle has generated much controversy over the years.
Modern quantum theory
Einstein was displeased with quantum theory and mechanics, despite its acceptance by other physicists, stating "God doesn't play with dice." As Einstein passed away at the age of 76 he still would not accept quantum theory. [87] In 1917, at the height of his work on relativity, Einstein published an article in Physikalische Zeitschrift that proposed the possibility of stimulated emission, the physical process that makes possible the maser and the laser.[88] This article showed that the statistics of absorption and emission of light would only be consistent with Planck's distribution law if the emission of light into a mode with n photons would be enhanced statistically compared to the emission of light into an empty mode. This paper was enormously influential in the later development of quantum mechanics, because it was the first paper to show that the statistics of atomic transitions had simple laws. Einstein discovered Louis de Broglie's work, and supported his ideas, which were received skeptically at first. In another major paper from this era, Einstein gave a wave equation for de Broglie waves, which Einstein suggested was the Hamilton–Jacobi equation of mechanics. This paper would inspire Schrödinger's work of 1926.
Bose–Einstein statistics
In 1924, Einstein received a description of a statistical model from Indian physicist Satyendra Nath Bose, based on a counting method that assumed that light could be understood as a gas of indistinguishable particles. Einstein noted that Bose's statistics applied to some atoms as well as to the proposed light particles, and submitted his translation of Bose's paper to the Zeitschrift für Physik. Einstein also published his own articles describing the model and its implications, among them the Bose–Einstein condensate phenomenon that some particulates should appear at very low temperatures.[89] It was not until 1995 that the first such condensate was produced experimentally by Eric Allin Cornell and Carl Wieman using ultra-cooling equipment built at the NISTJILA laboratory at the University of Colorado at Boulder.[90] Bose–Einstein statistics are now used to describe the behaviors of any assembly of bosons. Einstein's sketches for this project may be seen in the Einstein Archive in the library of the Leiden University.[69]
Energy momentum pseudotensor
General relativity includes a dynamical spacetime, so it is difficult to see how to identify the conserved energy and momentum. Noether's theorem allows these quantities to be determined from a Lagrangian with translation invariance, but general covariance makes translation invariance into something of a gauge symmetry. The energy and momentum derived within general relativity by Noether's presecriptions do not make a real tensor for this reason.
Einstein argued that this is true for fundamental reasons, because the gravitational field could be made to vanish by a choice of coordinates. He maintained that the non-covariant energy momentum pseudotensor was in fact the best description of the energy momentum distribution in a gravitational field. This approach has been echoed by Lev Landau and Evgeny Lifshitz, and others, and has become standard.
The use of non-covariant objects like pseudotensors was heavily criticized in 1917 by Erwin Schrödinger and others.
Unified field theory
Following his research on general relativity, Einstein entered into a series of attempts to generalize his geometric theory of gravitation to include electromagnetism as another aspect of a single entity. In 1950, he described his "unified field theory" in a Scientific American article entitled "On the Generalized Theory of Gravitation".[91] Although he continued to be lauded for his work, Einstein became increasingly isolated in his research, and his efforts were ultimately unsuccessful. In his pursuit of a unification of the fundamental forces, Einstein ignored some mainstream developments in physics, most notably the strong and weak nuclear forces, which were not well understood until many years after his death. Mainstream physics, in turn, largely ignored Einstein's approaches to unification. Einstein's dream of unifying other laws of physics with gravity motivates modern quests for a theory of everything and in particular string theory, where geometrical fields emerge in a unified quantum-mechanical setting.
Wormholes
Einstein collaborated with others to produce a model of a wormhole. His motivation was to model elementary particles with charge as a solution of gravitational field equations, in line with the program outlined in the paper "Do Gravitational Fields play an Important Role in the Constitution of the Elementary Particles?". These solutions cut and pasted Schwarzschild black holes to make a bridge between two patches.
If one end of a wormhole was positively charged, the other end would be negatively charged. These properties led Einstein to believe that pairs of particles and antiparticles could be described in this way.
Einstein–Cartan theory
In order to incorporate spinning point particles into general relativity, the affine connection needed to be generalized to include an antisymmetric part, called the torsion. This modification was made by Einstein and Cartan in the 1920s.
Equations of motion
The theory of general relativity has a fundamental law – the Einstein equations which describe how space curves, the geodesic equation which describes how particles move may be derived from the Einstein equations.
Since the equations of general relativity are non-linear, a lump of energy made out of pure gravitational fields, like a black hole, would move on a trajectory which is determined by the Einstein equations themselves, not by a new law. So Einstein proposed that the path of a singular solution, like a black hole, would be determined to be a geodesic from general relativity itself.
This was established by Einstein, Infeld, and Hoffmann for pointlike objects without angular momentum, and by Roy Kerr for spinning objects.
Other investigations
Einstein conducted other investigations that were unsuccessful and abandoned. These pertain to force, superconductivity, gravitational waves, and other research. Please see the main article for details.
Collaboration with other scientists
The 1927 Solvay Conference in Brussels, a gathering of the world's top physicists. Einstein in the center.
In addition to long time collaborators Leopold Infeld, Nathan Rosen, Peter Bergmann and others, Einstein also had some one-shot collaborations with various scientists.
Einstein–de Haas experiment
Einstein and De Haas demonstrated that magnetization is due to the motion of electrons, nowadays known to be the spin. In order to show this, they reversed the magnetization in an iron bar suspended on a torsion pendulum. They confirmed that this leads the bar to rotate, because the electron's angular momentum changes as the magnetization changes. This experiment needed to be sensitive, because the angular momentum associated with electrons is small, but it definitively established that electron motion of some kind is responsible for magnetization.
Schrödinger gas model
Einstein suggested to Erwin Schrödinger that he might be able to reproduce the statistics of a Bose–Einstein gas by considering a box. Then to each possible quantum motion of a particle in a box associate an independent harmonic oscillator. Quantizing these oscillators, each level will have an integer occupation number, which will be the number of particles in it.
This formulation is a form of second quantization, but it predates modern quantum mechanics. Erwin Schrödinger applied this to derive the thermodynamic properties of a semiclassical ideal gas. Schrödinger urged Einstein to add his name as co-author, although Einstein declined the invitation.[92]
Einstein refrigerator
In 1926, Einstein and his former student Leó Szilárd co-invented (and in 1930, patented) the Einstein refrigerator. This absorption refrigerator was then revolutionary for having no moving parts and using only heat as an input.[93] On 11 November 1930, U.S. Patent 1,781,541 was awarded to Albert Einstein and Leó Szilárd for the refrigerator. Their invention was not immediately put into commercial production, as the most promising of their patents were quickly bought up by the Swedish company Electrolux to protect its refrigeration technology from competition.[94]
Bohr versus Einstein
Einstein and Niels Bohr, 1925
The Bohr–Einstein debates were a series of public disputes about quantum mechanics between Albert Einstein and Niels Bohr who were two of its founders. Their debates are remembered because of their importance to the philosophy of science.[95][96][97]
In 1935, Einstein returned to the question of quantum mechanics. He considered how a measurement on one of two entangled particles would affect the other. He noted, along with his collaborators, that by performing different measurements on the distant particle, either of position or momentum, different properties of the entangled partner could be discovered without disturbing it in any way.
He then used a hypothesis of local realism to conclude that the other particle had these properties already determined. The principle he proposed is that if it is possible to determine what the answer to a position or momentum measurement would be, without in any way disturbing the particle, then the particle actually has values of position or momentum.
This principle distilled the essence of Einstein's objection to quantum mechanics. As a physical principle, it was shown to be incorrect when the Aspect experiment of 1982 confirmed Bell's theorem, which had been promulgated in 1964.
Political and religious views
Albert Einstein, seen here with his wife Elsa Einstein and Zionist leaders, including future President of Israel Chaim Weizmann, his wife Dr. Vera Weizmann, Menahem Ussishkin, and Ben-Zion Mossinson on arrival in New York City in 1921.
Albert Einstein's political views emerged publicly in the middle of the 20th century due to his fame and reputation for genius. Einstein offered to and was called on to give judgments and opinions on matters often unrelated to theoretical physics or mathematics (see main article).
Einstein's views about religious belief have been collected from interviews and original writings. These views covered Judaism, theological determinism, agnosticism, and humanism. He also wrote much about ethical culture, opting for Spinoza's god over belief in a personal god.
Non-scientific legacy
While travelling, Einstein wrote daily to his wife Elsa and adopted stepdaughters Margot and Ilse. The letters were included in the papers bequeathed to The Hebrew University. Margot Einstein permitted the personal letters to be made available to the public, but requested that it not be done until twenty years after her death (she died in 1986[98]). Barbara Wolff, of The Hebrew University's Albert Einstein Archives, told the BBC that there are about 3,500 pages of private correspondence written between 1912 and 1955.[99]
Einstein bequeathed the royalties from use of his image to The Hebrew University of Jerusalem. Corbis, successor to The Roger Richman Agency, licenses the use of his name and associated imagery, as agent for the university.[100]
In popular culture
In the period before World War II, Einstein was so well known in America that he would be stopped on the street by people wanting him to explain "that theory". He finally figured out a way to handle the incessant inquiries. He told his inquirers "Pardon me, sorry! Always I am mistaken for Professor Einstein."[101]
Einstein has been the subject of or inspiration for many novels, films, plays, and works of music.[102] He is a favorite model for depictions of mad scientists and absent-minded professors; his expressive face and distinctive hairstyle have been widely copied and exaggerated. Time magazine's Frederic Golden wrote that Einstein was "a cartoonist's dream come true".[103]
Awards and honors
Einstein received numerous awards and honors, including the Nobel Prize in Physics.
Publications
The following publications by Albert Einstein are referenced in this article. A more complete list of his publications may be found at List of scientific publications by Albert Einstein.
• Einstein, Albert (1901), "Folgerungen aus den Capillaritätserscheinungen (Conclusions Drawn from the Phenomena of Capillarity)", Annalen der Physik 4 (3): 513, Bibcode 1901AnP...309..513E, DOI:10.1002/andp.19013090306
• This annus mirabilis paper on the photoelectric effect was received by Annalen der Physik 18 March.
• Einstein, Albert (1905b), A new determination of molecular dimensions . This PhD thesis was completed 30 April and submitted 20 July.
• Einstein, Albert (1905c), "On the Motion – Required by the Molecular Kinetic Theory of Heat – of Small Particles Suspended in a Stationary Liquid", Annalen der Physik 17 (8): 549–560, Bibcode 1905AnP...322..549E, DOI:10.1002/andp.19053220806 . This annus mirabilis paper on Brownian motion was received 11 May.
• Einstein, Albert (1905d), "On the Electrodynamics of Moving Bodies", Annalen der Physik 17 (10): 891–921, Bibcode 1905AnP...322..891E, DOI:10.1002/andp.19053221004 . This annus mirabilis paper on special relativity was received 30 June.
• Einstein, Albert (1905e), "Does the Inertia of a Body Depend Upon Its Energy Content?", Annalen der Physik 18 (13): 639–641, Bibcode 1905AnP...323..639E, DOI:10.1002/andp.19053231314 . This annus mirabilis paper on mass-energy equivalence was received 27 September.
• Einstein, Albert (1915), "Die Feldgleichungen der Gravitation (The Field Equations of Gravitation)", Königlich Preussische Akademie der Wissenschaften: 844–847
• Einstein, Albert (1917a), "Kosmologische Betrachtungen zur allgemeinen Relativitätstheorie (Cosmological Considerations in the General Theory of Relativity)", Königlich Preussische Akademie der Wissenschaften
• Einstein, Albert (1917b), "Zur Quantentheorie der Strahlung (On the Quantum Mechanics of Radiation)", Physikalische Zeitschrift 18: 121–128, Bibcode 1917PhyZ...18..121E
• Einstein, Albert (11 July 1923), "Fundamental Ideas and Problems of the Theory of Relativity", Nobel Lectures, Physics 1901–1921, Amsterdam: Elsevier Publishing Company, archived from the original on 10 February 2007, retrieved 25 March 2007
• Einstein, Albert (1924), "Quantentheorie des einatomigen idealen Gases (Quantum theory of monatomic ideal gases)", Sitzungsberichte der Preussichen Akademie der Wissenschaften Physikalisch-Mathematische Klasse: 261–267 . First of a series of papers on this topic.
• Einstein, Albert (1926), "Die Ursache der Mäanderbildung der Flussläufe und des sogenannten Baerschen Gesetzes", Die Naturwissenschaften 14 (11): 223–224, Bibcode 1926NW.....14..223E, DOI:10.1007/BF01510300 . On Baer's law and meanders in the courses of rivers.
• Einstein, Albert; Podolsky, Boris; Rosen, Nathan (15 May 1935), "Can Quantum-Mechanical Description of Physical Reality Be Considered Complete?", Physical Review 47 (10): 777–780, Bibcode 1935PhRv...47..777E, DOI:10.1103/PhysRev.47.777
• Einstein, Albert (1940), "On Science and Religion", Nature (Edinburgh: Scottish Academic) 146 (3706): 605, Bibcode 1940Natur.146..605E, DOI:10.1038/146605a0, ISBN 0-7073-0453-9
• Einstein, Albert et al. (4 December 1948), "To the editors", New York Times (Melville, NY: AIP, American Inst. of Physics), ISBN 0-7354-0359-7
• Einstein, Albert (May 1949), "Why Socialism?", Monthly Review, archived from the original on 11 January 2006, retrieved 16 January 2006
• Einstein, Albert (1950), "On the Generalized Theory of Gravitation", Scientific American CLXXXII (4): 13–17
• Einstein, Albert (1954), Ideas and Opinions, New York: Random House, ISBN 0-517-00393-7
• Einstein, Albert (1969) (in German), Albert Einstein, Hedwig und Max Born: Briefwechsel 1916–1955, Munich: Nymphenburger Verlagshandlung, ISBN 3-88682-005-X
• Einstein, Albert (1979), Autobiographical Notes, Paul Arthur Schilpp (Centennial ed.), Chicago: Open Court, ISBN 0-87548-352-6 . The chasing a light beam thought experiment is described on pages 48–51.
• Collected Papers: Stachel, John, Martin J. Klein, a. J. Kox, Michel Janssen, R. Schulmann, Diana Komos Buchwald and others (Eds.) (1987–2006), The Collected Papers of Albert Einstein, Vol. 1–10, Princeton University Press Further information about the volumes published so far can be found on the webpages of the Einstein Papers Project and on the Princeton University Press Einstein Page
Notes
1. ^ "Albert's intellectual growth was strongly fostered at home. His mother, a talented pianist, ensured the children's musical education. His father regularly read Schiller and Heine aloud to the family. Uncle Jakob challenged Albert with mathematical problems, which he solved with 'a deep feeling of happiness'." More significant were the weekly visits of Max Talmud from 1889 through 1894 during which time he introduced the boy to popular scientific texts that brought to an end a short-lived religious phase, convincing him that 'a lot in the Bible stories could not be true'. A textbook of plane geometry that he quickly worked through led on to an avid self-study of mathematics, several years ahead of the school curriculum. [16]
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103. ^ Golden, Frederic (3 January 2000), "Person of the Century: Albert Einstein", Time, archived from the original on 21 February 2006, retrieved 25 February 2006
• Fölsing, Albrecht (1997): Albert Einstein: A Biography. New York: Penguin Viking. (Translated and abridged from the German by Ewald Osers.)
• Highfield, Roger; Carter, Paul (1993). The Private Lives of Albert Einstein. London: Faber and Faber. ISBN 978-0-571-16744-9.
• Hoffmann, Banesh, with the collaboration of Helen Dukas (1972): Albert Einstein: Creator and Rebel. London: Hart-Davis, MacGibbon Ltd.
• Isaacson, Walter (2007): Einstein: His Life and Universe. Simon & Schuster Paperbacks, New York. ISBN 978-0-7432-6473-0
• Moring, Gary (2004): The complete idiot's guide to understanding Einstein ( 1st ed. 2000). Indianapolis IN: Alpha books (Macmillan USA). ISBN 0-02-863180-3
• Pais, Abraham (1982): Subtle is the Lord: The science and the life of Albert Einstein. Oxford University Press. The definitive biography to date.
• Pais, Abraham (1994): Einstein Lived Here. Oxford University Press.
• Parker, Barry (2000): Einstein's Brainchild. Prometheus Books. A review of Einstein's career and accomplishments, written for the lay public.
• Schweber, Sylvan S. (2008): Einstein and Oppenheimer: The Meaning of Genius. Harvard University Press. ISBN 978-0-674-02828-9.
• Oppenheimer, J.R. (1971): "On Albert Einstein," p. 8–12 in Science and synthesis: an international colloquium organized by Unesco on the tenth anniversary of the death of Albert Einstein and Teilhard de Chardin, Springer-Verlag, 1971, 208 pp. (Lecture delivered at the UNESCO House in Paris on 13 December 1965.) Also published in The New York Review of Books, 17 March 1966, On Albert Einstein by Robert Oppenheimer
Contenu de sensagent
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Jeux de lettres
Les jeux de lettre français sont :
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○ jokers, mots-croisés
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○ Boggle.
Lettris
Lettris est un jeu de lettres gravitationnelles proche de Tetris. Chaque lettre qui apparaît descend ; il faut placer les lettres de telle manière que des mots se forment (gauche, droit, haut et bas) et que de la place soit libérée.
boggle
Il s'agit en 3 minutes de trouver le plus grand nombre de mots possibles de trois lettres et plus dans une grille de 16 lettres. Il est aussi possible de jouer avec la grille de 25 cases. Les lettres doivent être adjacentes et les mots les plus longs sont les meilleurs. Participer au concours et enregistrer votre nom dans la liste de meilleurs joueurs ! Jouer
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Principales Références
La plupart des définitions du français sont proposées par SenseGates et comportent un approfondissement avec Littré et plusieurs auteurs techniques spécialisés.
Le dictionnaire des synonymes est surtout dérivé du dictionnaire intégral (TID).
L'encyclopédie française bénéficie de la licence Wikipedia (GNU). | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 1, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.4595873951911926, "perplexity": 3928.792078145434}, "config": {"markdown_headings": false, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2021-49/segments/1637964358153.33/warc/CC-MAIN-20211127073536-20211127103536-00254.warc.gz"} |
https://open.kattis.com/problems/encodedmessage | Kattis
# Encoded Message
Alex wants to send a love poem to his girlfriend Bridget. Unfortunately, she has a nosy friend, Ellen, who might intercept his message and invade their privacy.
To prevent this, Alex has invented a scheme to make his missives indecipherable to Ellen. He arranges the letters into a square, which is rotated a quarter-turn clockwise, and then he puts the resulting letters on a single line again. (For simplicity’s sake, Alex doesn’t use whitespace or punctuation in his poems.)
For example, the text “RosesAreRedVioletsAreBlue” would be encoded as
eedARBtVrolsiesuAoReerles” using the following intermediate steps:
R o s e s A r e R e d V i o l e t s A r e B l u e
$\Rightarrow$
e e d A R B t V r o l s i e s u A o R e e r l e s
Ellen has intercepted some of Alex’s messages but they make no sense to her. Can you write a program to help her decode them?
## Input
On the first line one positive number: the number of test cases, at most 100. After that per test case:
• one line with an encoded message: a string consisting of upper-case and lower-case letters only. The length of the message is a square between 1 and 10 000 characters.
## Output
Per test case:
• one line with the original message.
Sample Input 1 Sample Output 1
3
RSTEEOTCP
eedARBtVrolsiesuAoReerles
EarSvyeqeBsuneMa
TOPSECRET
RosesAreRedVioletsAreBlue
SquaresMayBeEven | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 1, "mathjax_display_tex": 0, "mathjax_asciimath": 1, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.4234292507171631, "perplexity": 2801.6237942357716}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2020-29/segments/1593655879738.16/warc/CC-MAIN-20200702174127-20200702204127-00524.warc.gz"} |
https://www.math.sissa.it/publications?page=14&%3Bf%5Bauthor%5D=256&s=title&o=asc | ## Publications
Export 1603 results:
D
Dubrovin B. Dispersion relations for non-linear waves and the Schottky problem. In: Important developments in soliton theory / A. S. Fokas, V. E. Zakharov (eds.) - Berlin : Springer-Verlag, 1993. - pages : 86-98. Important developments in soliton theory / A. S. Fokas, V. E. Zakharov (eds.) - Berlin : Springer-Verlag, 1993. - pages : 86-98. SISSA; 1993. Available from: http://hdl.handle.net/1963/6480
. Dispersive Estimates for Schrödinger Operators with Point Interactions in ℝ3. In: Advances in Quantum Mechanics: Contemporary Trends and Open Problems. Advances in Quantum Mechanics: Contemporary Trends and Open Problems. Cham: Springer International Publishing; 2017. pp. 187–199. Available from: https://doi.org/10.1007/978-3-319-58904-6_11
. A distributed lagrange formulation of the finite element immersed boundary method for fluids interacting with compressible solids. In: Mathematical and Numerical Modeling of the Cardiovascular System and Applications. Vol. 16. Mathematical and Numerical Modeling of the Cardiovascular System and Applications. Cham: Springer International Publishing; 2018. pp. 1–21. Available from: https://arxiv.org/abs/1712.02545v1
. Double resonance with Landesman–Lazer conditions for planar systems of ordinary differential equations. Journal of Differential Equations [Internet]. 2011 ;250:1052 - 1082. Available from: http://www.sciencedirect.com/science/article/pii/S0022039610002901
. Drift in phase space: a new variational mechanism with optimal diffusion time. J. Math. Pures Appl. 82 (2003) 613-664 [Internet]. 2003 . Available from: http://hdl.handle.net/1963/3020
. Duality, biorthogonal polynomials and multi-matrix models. Comm. Math. Phys. 2002 ;229:73–120.
. The duality of spectral curves that arises in two-matrix models. Teoret. Mat. Fiz. 2003 ;134:32–45.
. A dynamical feedback model for adaptation in the olfactory transduction pathway. Biophysical Journal. Volume 102, Issue 12, 20 June 2012, Pages 2677-2686 [Internet]. 2012 . Available from: http://hdl.handle.net/1963/7019
. Dynamics control by a time-varying feedback. Journal of Dynamical and Control Systems. Volume 16, Issue 2, April 2010, Pages :149-162 [Internet]. 2010 . Available from: http://hdl.handle.net/1963/6461
Altafini C. Dynamics of opinion forming in structurally balanced social networks. PloS one. 2012 ; 7(6):e38135 [Internet]. 2012 . Available from: http://hdl.handle.net/1963/6051
E
. Early phase of plasticity-related gene regulation and SRF dependent transcription in the hippocampus. PloS one. Volume 8, Issue 7, July 2013 : e68078 [Internet]. 2013 . Available from: http://hdl.handle.net/1963/7287
. Editorial. [Internet]. 2014 . Available from: http://urania.sissa.it/xmlui/handle/1963/34712
. Effective dynamics for Bloch electrons: Peierls substitution and beyond. [Internet]. 2003 . Available from: http://hdl.handle.net/1963/3040
. Effective inverse spectral problem for rational Lax matrices and applications. Int. Math. Res. Not. IMRN. 2007 :Art. ID rnm103, 39.
Olgiati A. Effective Non-linear Dynamics of Binary Condensates and Open Problems. In: Advances in Quantum Mechanics: Contemporary Trends and Open Problems. Advances in Quantum Mechanics: Contemporary Trends and Open Problems. Cham: Springer International Publishing; 2017. pp. 239–256. Available from: https://doi.org/10.1007/978-3-319-58904-6_14
. Effective non-linear spinor dynamics in a spin-1 Bose–Einstein condensate. Journal of Physics A: Mathematical and Theoretical [Internet]. 2018 ;51:405201. Available from: https://doi.org/10.1088%2F1751-8121%2Faadbc2
. Effective Schroedinger dynamics on $ε$-thin Dirichlet waveguides via Quantum Graphs I: star-shaped graphs. J. Phys. A 43 (2010) 474014 [Internet]. 2010 . Available from: http://hdl.handle.net/1963/4106 | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 1, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.15253368020057678, "perplexity": 4929.759305312343}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2021-31/segments/1627046153521.1/warc/CC-MAIN-20210728025548-20210728055548-00605.warc.gz"} |
https://proofwiki.org/wiki/Equivalence_of_Definitions_of_Transitive_Closure_(Relation_Theory)/Intersection_is_Smallest/Proof_2 | # Equivalence of Definitions of Transitive Closure (Relation Theory)/Intersection is Smallest/Proof 2
## Theorem
Let $\mathcal R$ be a relation on a set $S$.
Then the intersection of all transitive relations on $S$ that contain $\mathcal R$ is the smallest transitive relation on $S$ that contains $\mathcal R$.
## Proof
Note that the trivial relation $\mathcal T = S \times S$ on $S$ contains $\mathcal R$, by the definition of a relation on $S$.
Further, $\mathcal T$ is transitive by Trivial Relation is Equivalence.
Thus there is at least one transitive relation on $S$ that contains $\mathcal R$.
Now define $\mathcal R^+$ as the intersection of all transitive relations on $S$ that contain $\mathcal R$:
$\displaystyle \mathcal R^+ := \bigcap \left\{{\mathcal R': \text{$\mathcal R'$is transitive and$\mathcal R \subseteq \mathcal R'$}}\right\}$
By Intersection of Transitive Relations is Transitive, $\mathcal R^+$ is also a transitive relation on $S$.
By Set Intersection Preserves Subsets, it also holds that $\mathcal R \subseteq \mathcal R^+$.
Lastly, by Intersection is Subset, for any transitive relation $\mathcal R'$ containing $\mathcal R$, it must be that $\mathcal R^+ \subseteq \mathcal R'$.
Thus $\mathcal R^+$ is indeed the smallest transitive relation on $S$ containing $\mathcal R$.
$\blacksquare$ | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 1, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.9958811402320862, "perplexity": 95.68443796380687}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2019-51/segments/1575540531917.10/warc/CC-MAIN-20191211131640-20191211155640-00268.warc.gz"} |
https://getrevising.co.uk/diagrams/the-history-of-the-atom-3 | # The History of The Atom
• Atoms - Lesson 4 - History of the Atom
• John Dalton published his ideas about atoms in 1803. He thought that all matter was made of tiny particles called atoms, which he imagined as tiny spheres that could not be divided.
• Nearly 100 years later, J J Thomson carried out experiments and discovered the electron. This led him to suggest the plum pudding model of the atom. In this model, the atom is a ball of positive charge with negative electrons embedded in it - like currants in a Christmas pudding.
• In 1909 Ernest Rutherford designed an experiment to test the plum pudding model. In the experiment, positively charged alpha particles were fired at thin gold foil. Most alpha particles went straight through the foil. But a few were scattered in different directions.
• This evidence led Rutherford to suggest a new model for the atom, called the nuclear model. In the nuclear model:the mass of an atom is concentrated at its centre, the nucleusthe nucleus is positively charged
• Niels Bohr adapted Ernest Rutherford's nuclear model. Bohr did calculations that led him to suggest that electrons orbit the nucleus in shells. The shells are at certain distances from the nucleus. The calculations agreed with observations from experiments.
• This evidence led Rutherford to suggest a new model for the atom, called the nuclear model. In the nuclear model:the mass of an atom is concentrated at its centre, the nucleusthe nucleus is positively charged
• Further experiments led to the idea that the nucleus contained small particles, called protons. Each proton has a small amount of positive charge.
• In 1932 James Chadwick found evidence for the existence of particles in the nucleus with mass but no charge. These particles are called neutrons. This led to another development of the atomic model, which is still used today. | {"extraction_info": {"found_math": false, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.8795405626296997, "perplexity": 800.9680331945468}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2019-43/segments/1570986660067.26/warc/CC-MAIN-20191015155056-20191015182556-00447.warc.gz"} |
http://www.koreascience.or.kr/search.page?keywords=validation | • Title, Summary, Keyword: validation
### Validation of Sterilization Process (멸균제제공정의 Validation)
• 김길수
• YAKHAK HOEJI
• /
• v.29 no.5
• /
• pp.305-315
• /
• 1985
• Validation이란 용어는 1970년대에 우리나라에 GMP개념이 도입되면서 처음 사용되기 시작하여 지금은 흔히들 사용하면서도 그 개념은 아직도 정확히 이해되고 있지 않은것 같다. 제약공업에서의 validation의 적용범위는 아주 광범위하며 제조기기, 제조공정, 조직, 인원 등에 그 개념을 도입하여 관리하고 있다. 따라서 본 란에서는 validation의 일반적인 개념을 서술한 후 액상제제 특히 무균제제에 대한 calidation중 멸균공정에 대하여 상술하고자 한다.
### Candidate Points and Representative Cross-Validation Approach for Sequential Sampling (후보점과 대표점 교차검증에 의한 순차적 실험계획)
• Kim, Seung-Won;Jung, Jae-Jun;Lee, Tae-Hee
• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.31 no.1
• /
• pp.55-61
• /
• 2007
• Recently simulation model becomes an essential tool for analysis and design of a system but it is often expensive and time consuming as it becomes complicate to achieve reliable results. Therefore, high-fidelity simulation model needs to be replaced by an approximate model, the so-called metamodel. Metamodeling techniques include 3 components of sampling, metamodel and validation. Cross-validation approach has been proposed to provide sequnatially new sample point based on cross-validation error but it is very expensive because cross-validation must be evaluated at each stage. To enhance the cross-validation of metamodel, sequential sampling method using candidate points and representative cross-validation is proposed in this paper. The candidate and representative cross-validation approach of sequential sampling is illustrated for two-dimensional domain. To verify the performance of the suggested sampling technique, we compare the accuracy of the metamodels for various mathematical functions with that obtained by conventional sequential sampling strategies such as maximum distance, mean squared error, and maximum entropy sequential samplings. Through this research we team that the proposed approach is computationally inexpensive and provides good prediction performance.
### Delegated Attribute Certificate Validation And Protocol (PMI 인증서 검증 위임 및 검증 프로토콜)
• 이승훈;송주석
• Journal of the Korea Institute of Information Security & Cryptology
• /
• v.13 no.1
• /
• pp.59-67
• /
• 2003
• PMI(Privilege Management Infrastructure) certificates as well as Public-Key certificates must be validated before being used. Validation for a PMI certificate requires PMI certificate path validation, and PKC(Public-Key Certificate) path validations for each entity in the PMI certificate path. This validation work is quite complex and burdened to PMI certificate verifiers. Therefore, this paper suggests a delegated PMI certificate validation that uses specialized validation server, and defines a validation protocol which is used between validation server and client.
### Improvement of Performance for Online Certificate Status Validation (실시간 인증서 상태검증의 성능개선)
• Jung, Jai-Dong;Oh, Hae-Seok
• The KIPS Transactions:PartC
• /
• v.10C no.4
• /
• pp.433-440
• /
• 2003
• According as the real economic activities are carried out in the cyber world and the identity problem of a trade counterpart emerges, digital signature has been diffused. Due to the weakness for real-time validation using the validation method of digital signature, Certificate Revocation List, On-line Certificate Status Protocol was introduced. In this case, every transaction workload requested to verify digital signature is concentrated of a validation server node. Currently this method has been utilized on domestic financial transactions, but sooner or later the limitation will be revealed. In this paper, the validation method will be introduced which not only it can guarantee real-time validation but also the requesting node of certificate validation can maintain real-time certificate status information. This method makes the revocation management node update the certificate status information in real-time to the validation node while revoking certificate. The characteristic of this method is that the revocation management node should memorize the validation nodes which a certificate holder uses. If a certificate holder connects a validation node for the first time, the validation node should request its certificate status information to the above revocation management node and the revocation management node memorizes the validation node at the time. After that, the revocation management node inform the revocation information in real-time to all the validation node registered when a request of revocation happens. The benefits of this method are the fact that we can reduce the validation time because the certificate validation can be completed at the validation node and that we can avoid the concentration of requesting certificate status information to a revocation node.
### Bandwidth selections based on cross-validation for estimation of a discontinuity point in density (교차타당성을 이용한 확률밀도함수의 불연속점 추정의 띠폭 선택)
• Huh, Jib
• Journal of the Korean Data and Information Science Society
• /
• v.23 no.4
• /
• pp.765-775
• /
• 2012
• The cross-validation is a popular method to select bandwidth in all types of kernel estimation. The maximum likelihood cross-validation, the least squares cross-validation and biased cross-validation have been proposed for bandwidth selection in kernel density estimation. In the case that the probability density function has a discontinuity point, Huh (2012) proposed a method of bandwidth selection using the maximum likelihood cross-validation. In this paper, two forms of cross-validation with the one-sided kernel function are proposed for bandwidth selection to estimate the location and jump size of the discontinuity point of density. These methods are motivated by the least squares cross-validation and the biased cross-validation. By simulated examples, the finite sample performances of two proposed methods with the one of Huh (2012) are compared.
### Basic Principles of the Validation for Good Laboratory Practice Institutes
• Cho, Kyu-Hyuk;Kim, Jin-Sung;Jeon, Man-Soo;Lee, Kyu-Hong;Chung, Moon-Koo;Song, Chang-Woo
• Toxicological Research
• /
• v.25 no.1
• /
• pp.1-8
• /
• 2009
• Validation specifies and coordinates all relevant activities to ensure compliance with good laboratory practices (GLP) according to suitable international standards. This includes validation activities of past, present and future for the best possible actions to ensure the integrity of non-clinical laboratory data. Recently, validation has become increasingly important, not only in good manufacturing practice (GMP) institutions but also in GLP facilities. In accordance with the guideline for GLP regulations, all equipments used to generate, measure, or assess data should undergo validation to ensure that this equipment is of appropriate design and capacity and that it will consistently function as intended. Therefore, the implantation of validation processes is considered to be an essential step in a global institution. This review describes the procedures and documentations required for validation of GLP. It introduces basic elements such as the validation master plan, risk assessment, gap analysis, design qualification, installation qualification, operational qualification, performance qualification, calibration, traceability, and revalidation.
### Mean-Variance-Validation Technique for Sequential Kriging Metamodels (순차적 크리깅모델의 평균-분산 정확도 검증기법)
• Lee, Tae-Hee;Kim, Ho-Sung
• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.34 no.5
• /
• pp.541-547
• /
• 2010
• The rigorous validation of the accuracy of metamodels is an important topic in research on metamodel techniques. Although a leave-k-out cross-validation technique involves a considerably high computational cost, it cannot be used to measure the fidelity of metamodels. Recently, the mean$_0$ validation technique has been proposed to quantitatively determine the accuracy of metamodels. However, the use of mean$_0$ validation criterion may lead to premature termination of a sampling process even if the kriging model is inaccurate. In this study, we propose a new validation technique based on the mean and variance of the response evaluated when sequential sampling method, such as maximum entropy sampling, is used. The proposed validation technique is more efficient and accurate than the leave-k-out cross-validation technique, because instead of performing numerical integration, the kriging model is explicitly integrated to accurately evaluate the mean and variance of the response evaluated. The error in the proposed validation technique resembles a root mean squared error, thus it can be used to determine a stop criterion for sequential sampling of metamodels.
### A New Certificate Validation Scheme for Delegating the Digital Signature Verification (디지틀 서명 검증을 위임하기 위한 새로운 인증서 검증 기법)
• Choi Yeon-Hee;Park Mi-Og;Jun Moon-Seog
• Journal of Internet Computing and Services
• /
• v.4 no.4
• /
• pp.53-64
• /
• 2003
• To perform the certificate validation on the user-side application induces the very considerable overhead on the user-side system because of the complex and time-consuming characteristic of the validation processing. Most of the time spend for performing the validation processing is required for the digital signature verification, since the verification accompanies with the cryptographic calculation over each certificate on the certificate path. In this paper, we propose a new certificate validation scheme using DSVP(Delegated Signature Validation Protocol) which can reduce the overhead for the user-side certificate validation processing. It is achieved by delegating the digital signature verification to CAs of the PKI domain. As the proposed DSVP is the protocol performed between a user and CAs, it is applied to the hierarchical PKI efficiently and used for delegating the digital signature verification reliably and safely, our proposed scheme can not only reduces the overhead for the validation processing by decreasing the cryptographic calculation but also improves the utilization of CAs by employing them to the validation processing.
### Validation Technique using variance and confidence interval of metamodel (근사모델의 분산과 신뢰구간을 이용한 모델의 정확도 평가법)
• Han, In-Sik;Lee, Yong-Bin;Choi, Dong-Hoon
• Proceedings of the KSME Conference
• /
• /
• pp.1169-1175
• /
• 2008
• The validation technique is classified with two methods whether to demand of additional experimental points. The method which requires additional experimental points such as RSME is actually impossible in engineering field. Therefore, the method which only use experimented points such as the cross validation technique is only available. But the cross validation not only requires considerable computational costs for generating metamodel each iterations, but also cannot measure quantitatively the fidelity of metamodel. In this research we propose a new validation technique for representative metamodels using an variance of metamodel and confidence interval information. The proposed validation technique computes confidence intervals using a variance information from the metamodel. This technique will have influence on choosing the accurate metamodel, constructing ensemble of each metamodels and advancing effectively sequential sampling technique.
### A Case Study on the Validation of the Rolling Stock Requirement Statement (철도차량 요구사항서 논증 활동 사례 연구)
• Kim Jin-Ill;Kim Jin-Hoon
• Journal of the Korea Institute of Military Science and Technology
• /
• v.7 no.2
• /
• pp.57-64
• /
• 2004
• A Requirement statement validation process is suggested which was established and applied to the rolling stock development project of the Korean Railway Research Institute. The validation process includes team organization, selection of validation criteria, development of validation template, education of team members, validation, construction of database and management of requirement change. Many defects in the specification of requirement were found to be associated with the problem of non-uniqueness, describing solution instead of problem, ambiguity and redundancy. This paper described detailed activities at each step of the validation process and lessons learned from these activities. | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 1, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.5789770483970642, "perplexity": 5513.508471928426}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2021-25/segments/1623488504838.98/warc/CC-MAIN-20210621212241-20210622002241-00057.warc.gz"} |
https://dongan-group.com.vn/sin-2x-cos-2x-1/ | # Trigonometry
The standard proof of the identity $sin^2x + cos^2x = 1$ (the one that is taught in schools) is as follows: from pythagoras theorem, we have (where $h$ is hypotenuse, $b$ is base and $p$ is perpendicular)$$h^2 = p^2 + b^2$$dividing by $h^2$ on both sides:$$1 = fracp^2h^2+fracb^2h^2$$since $sin x = frac ph$ and $cos x = frac bh$, $$1 = sin^2x+cos^2x$$
Are there any more innovative ways of proving this common identity?
Here"s a couple of different methods:
Proof using the cosine angel sum formula:$$1=cos(0) =cos(x + (-x)) =cos(x)cos(-x) - sin(x)sin(-x) = cos^2(x) + sin^2(x)$$Proof using differential equations:Recall the differential equation definitions of $sin$ and $cos$: They are the solutions to $f"" = - f$ with the appropriate initial conditions $f(0) = 0$, $f"(0) = 1$ for $sin(x)$ & $f(0) = 1$, $f"(0) = 0$ for $cos(x)$. Since solutions to differential equations are quality given the initial conditions, we immediately get $sin"(x) = cos(x)$ under this definition. Then:egineqnarrayfracddx left(sin^2(x) + cos^2(x) ight) &=& fracddx left(sin^2(x) + left(sin"(x) ight)^2 ight)\&=& 2sin(x)sin"(x) + 2sin"(x)sin""(x)\&=& 2sin(x)sin"(x) +2sin"(x)(-sin(x)) = 0endeqnarrayhence $sin^2(x) + cos^2(x)$ is constant, since its derivative is 0. Plugging in $x=0$ we see that it must equal 1.
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Proof using Euler"s formula: $$sin^2(x) + cos^2(x) = left(cos x + i sin x ight)left(cos x - i sin x ight) =left(cos x + i sin x ight)left(cos (-x) + i sin (-x) ight)= e^i x e^-i x = 1$$Proof using Taylor series:Using the Taylor series:egineqnarraysin(x) = sum_n=0^infty frac(-1)^n x^2n+1(2n+1)!\cos(x) = sum_n=0^infty frac(-1)^n x^2n(2n)!endeqnarraywe have $$sin^2(x) = left(sum_n=0^infty frac(-1)^n x^2n+1(2n+1)! ight)^2 = sum_n=0^infty sum_m=0^infty frac(-1)^n+m x^2n + 2m + 2(2n+1)!(2m+1)! = sum_k=0^infty x^2k+2(-1)^k sum_j=0^k frac1(2j+1)!(2(k-j)+1)!= sum_k=0^infty fracx^2k+2(-1)^k(2k+2)!sum_j=0^k inom2k+22j+1 = -sum_k=1^infty fracx^2k(-1)^k(2k)!sum_j=0^k-1 inom2k2j+1$$and $$cos^2(x) =left(sum_n=0^infty frac(-1)^n x^2n(2n)! ight)^2 = sum_n=0^infty sum_m=0^infty frac(-1)^n+m x^2n + 2m(2n)!(2m)! = sum_k=0^infty x^2k(-1)^k sum_j=0^k frac1(2j)!(2(k-j))! = sum_k=0^infty fracx^2k(-1)^k(2k)!sum_j=0^k inom2k2j = 1 + sum_k=1^infty fracx^2k(-1)^k(2k)!sum_j=0^k inom2k2j$$Adding these together:$$sin^2(x) + cos^2(x) = 1+sum_k=1^inftyfracx^2k(-1)^k(2k)!left(sum_j=0^k inom2k2j-sum_j=0^k-1 inom2k2j+1 ight)=1+sum_k=1^inftyfracx^2k(-1)^k(2k)!left(sum_j=0^2k (-1)^jinom2kj ight) = 1+sum_k=1^inftyfracx^2k(-1)^l(2k)! (1 + (-1))^2k = 1$$We use the binomial theorem on the second last step.
Carlson"s Theorem: Major overkill khổng lồ use this one, but it still works.
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Notice $cos(x)$, & $sin(x)$ have exponential type 1. Thus $$f(x) = cos^2(fracpi4x) + sin^2(fracpi4x) - 1$$has exponential type at most $fracpi2 . By inspection, you can see that$f(x) = 0$for$xin dongan-group.com.vnbbN$. Hence Carlson"s theorem implies$f(x) = 0\$ identically. | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 1, "mathjax_display_tex": 1, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.9715214967727661, "perplexity": 6386.249561750053}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 20, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2023-06/segments/1674764500058.1/warc/CC-MAIN-20230203154140-20230203184140-00780.warc.gz"} |
https://quantumcomputing.stackexchange.com/questions/17881/why-cant-quantum-computation-replace-classical-computation/17891#17891 | # Why can't quantum computation replace classical computation?
I am not a total novice of quantum computation (have read the first 6 chapters of Nielsen and Chuang, though not familiar with every part), but there are some fundamental questions that I don't know answers well. One question that has bothered me is that I often hear comments which say that quantum computers can not be regarded as a replacement for classical ones.
However, we also know that all classical circuits can be simulated by quantum circuits. Put it another way, every Boolean function $$f:\{0,1\}^k\to\{0,1\}$$ can be computed by using a quantum circuit.
So, how to correctly understand the problems that a quantum computer might encounter when doing a classical computer's job? I know a strong restriction on quantum computing is that we can't read the resulting qubits state directly, but has to use quantum measurement so that we can only get one of the computational basis states probabilistically. However, I don't see this is a difficulty if what we want to do is only to compute a Boolean function.
Following are some possible answers I've thought of:
1. Quantum computers can do everything classical computers do, but no more efficiently if we only use the standard technique to simulate classical circuits. Quantum computers outperform classical ones only when special quantum algorithms exploiting superpositions of quantum states are applied, such as the quantum Fourier transform (QFT).
2. In Nielsen and Chuang (Section 5.1), it says QFT cannot replace classical discrete Fourier transform. Besides the problem that the amplitudes cannot be directly accessed by measurement, it points out that the worse problem is that "there is in general no way to efficiently prepare the original state to be Fourier transformed." Maybe such kind of problems is important for many applications.
Are the above answers right? Are there other important reasons quantum computers cannot replace the classical ones?
• Jun 9 '21 at 21:39
In the general case, I think the first answer you listed is pretty accurate. At the moment, quantum hardware is expensive and replacing classical with quantum would imply simulating the billions of transistors present in modern computers. If we have efficient algorithms to perform these tasks, why would we bother on performing the exact same algorithms with the same exact techniques but with way more expensive hardware? We are not getting any performance improvement.
That's why it is very often said that quantum computers will not replace classical computers, but rather be of help to classical computers. Take for example Shor's algorithm. This algorithm is divided into a classical and a quantum part. The quantum part performs something that cannot be efficiently done in a classical computer: estimate the phase of an eigenvector of a unitary operator. Then, the classical part uses this result to finish factorizing. VQE has a similar dynamic, where the quantum part simulates the molecule and a classical optimizer tweaks the parameters of the circuit.
Something else to consider is the probabilistic nature of quantum computers. Eventhough error correction techniques are being developed and better hardware is being developed, the probabilistic nature of quantum computing will always be there. On the other side, classical computers have very small error rates, which make them suitable very reliable. And the probabilistic nature of quantum computers isn't something bad, it is one of the things that makes them so powerful, but it isn't the best option to run the classical algorithms and software developed.
tl;dr: No, quantum computers will not replace classical computers. Both systems coexist and each will specialize on those tasks they can do better.
In my opinion, quantum computers can't replace classical computers, because there are many tasks where classical algorithms are optimized, so why do we replace something which works quickly and accurately with something which works quickly but it doesn't have the same precision? It is more logical to use quantum computers only where classical computers fail in terms of performance
Sure, you can achieve quantum supremacy, meaning you can do certain tasks way faster on quantum computers than on any classical supercomputers.
But the physical implementation of a quantum computer is hard because of many things: small decoherence time of qubits, some amount of error in implementing quantum gates (which will be increased if you add more and more gates), noise.
Now, just to do a simple addition on a quantum computer is a tedious task. See elementary operation.
And a classical computer does millions of computations per second. To achieve this on a quantum computer, you will probably need millions of gates as you need to convert certain gates to elementary gates. And quantum computers do have some limitations which I mentioned earlier.
So, in my opinion, it is physically impossible to simulate a classical computer on a quantum computer.
Contrary to the hypothesis and the other answers here, I don't think there is any reason why quantum computation can not replace classical computation. It certainly won't in the near future, but who's to say what the rate of progress will be?
One has to understand the two main proponents behind classical computation devices in use today: transistors and photolithography. They created the digital revolution that allows you to carry a device with billions of computational gates in your pocket. 70 years ago you could only have 20,000 transistors in a complete room. 70 years is not a very long time in the big picture.
Who's to say what the state of computational devices will be in a 1000 years? Perhaps a strategy as effective as photolithography will be found for the construction of quantum computers, perhaps not.
Quantum computers can do everything classical computers do, but no more efficiently if we only use the standard technique to simulate classical circuits.
This is misleading. There is a linear time and space mapping from a classical circuit to a quantum circuit. How 'efficient' either of those is depends entirely on the constants involved. Right now the constants for quantum machines are awful, but that may change.
In Nielsen and Chuang (Section 5.1), it says QFT cannot replace classical discrete Fourier transform. Besides the problem that the amplitudes cannot be directly accessed by measurement, it points out that the worse problem is that "there is in general no way to efficiently prepare the original state to be Fourier transformed." Maybe such kind of problems is important for many applications.
You certainly can do a classical Discrete Fourier Transform on a quantum computer (as you can any other classical algorithm). The point of N&C is not to say that quantum computers can't do classical DFT, their point is that QFT is a distinct algorithm with different input/output assumptions.
Your question talks about the theoretical capabilities of theoretical computers. Anyone who says that quantum computers won't replace classical computers is probably talking about the actual capabilities of actual computers.
Obviously, current quantum computers can't replace current classical computers. I doubt that that will ever change. The reason is that quantum computations have to happen in perfect thermodynamic isolation from the environment, and that severely limits the hardware design space. Quantum computing hardware could only compete in speed with classical hardware on classical algorithms if the optimal point in the quantum design space happened to coincide with the optimal point in the much larger classical design space, and I see no reason why that would happen.
Quantum hardware might de-facto replace classical hardware if it had enough advantages to compensate for the price/performance disadvantage. But I don't know of a single CPU-intensive task that people routinely run on personal or business computers that would be sped up by any known quantum algorithm. There are scientific applications (simulation of quantum systems, at least), but I think most people would have no reason to pay a premium for a quantum-capable processor unless someone discovers a killer app. | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 1, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.7324775457382202, "perplexity": 489.5215155271597}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2022-05/segments/1642320301488.71/warc/CC-MAIN-20220119185232-20220119215232-00384.warc.gz"} |
http://mikequentelsoftware.blogspot.com/ | ## 2013-07-28
### Comparing Methods of Riemann Sums in Python
The Riemann Sum of the region under a continuous function can be used to define the integration of that function. In studying integral calculus, it helps to compare the ways that the sum of rectangles or trapezoids in approximating the integral of such a function. To make this easier to visualise, the Python library Matplotlib provides adequate tools for presenting such a comparision of Riemann Sum operations, whether using rectangles or trapezoids. Here, I show a simple demo of both the sum of rectangles as well as the sum of trapezoids to compare these approximations to the "exact" area as calculated by the integrate.quad function of the Python library Scipy.
This demo also includes a DiscreteSlider class as Joe Kington provided in a thread at Stackoverflow (many thanks to Joe for sharing this).
The demo uses a slider control to change the number of panels (rectangles and trapezoids) to change the resolution of the approximation of the area under a curve. As the number of panels increases, the width of each panel decreases, thus increasing the resolution; one can see the resolution slowly approach the "exact" area calculated whilst sliding the control to the right. The rectangular area ("Mid Sum Area") is calculated using the midpoint method; the trapezoid area ("Trap Sum Area") is calculated using trapezoids at the same x boundaries.
## 2012-12-05
### RGB and HSV Colour Selector Demo in Python
The use of red-green-blue (RGB) tuples along with hue-saturation-value (HSV) tuples is quite common in many software, such as in the colour selection feature of GIMP. Alvy Ray Smith describes the conversion between the two colour spaces in an article Color Gamut Transform Pairs” in the August 1978 issue of SIGGRAPH 78 Conference Proceedings.
Based on the algorithms in Smith's article, I've implemented a Python colour selector demo (downloadable at http://github.com/mikequentel/rgb_hsv or http://downloads.mikequentel.com/rgbhsv.py.tar.gz) to show how a colour can be set using either RGB or HSV settings. The code listing of the demo shows even the same variable naming conventions as the pseudocode in Smith's article, to make it easier to compare to the algorithm.
Here is a screenshot of the demo in action:
The demo uses a Tkinter GUI and the standard, out-of-the box library functionality that comes with Python 2.7. The colour swatch (rectangle) is simply the background of a Canvas object. This is meant to be a very simple, easy-to-understand demo of how to convert between RGB and HSV. The code is not meant to be an optimised example of how to generate GUI widgets; no special design patterns that generalise the creation of widgets are used.
As the demo has about 300 lines of code, I will only show here snippets of the functions that convert between RGB and HSV.
def rgb2hsv(R, G, B):
print "Start of rgb2hsv()"
if R == G == B == 0.0:
return {'h':0, 's':0, 'v':0}
# DETERMINES MAXIMUM RGB VALUE "V" WHICH IS A MEASURE OF THE DEPARTURE
# FROM BLACK.
V = max(R, G, B)
# DETERMINES MININUM RGB VALUE "X".
X = min(R, G, B)
# DETERMINES SATURATION "S".
S = (V - X)/V
# DETERMINES ADJUSTED RED, GREEN, BLUE VALUES "r", "g", "b".
r = (V - R)/(V - X)
g = (V - G)/(V - X)
b = (V - B)/(V - X)
# DETERMINES HUE "H"
H = 0
if R == V:
H = G == X and 5 + b or 1 - g
if G == V:
H = B == X and 1 + r or 3 -b
else:
H = R == X and 3 + g or 5 - r
H /= 6.0
hue = toDegrees(H)
saturation = toRoundedPercentage(S)
value = toRoundedPercentage(V)
return {'h':hue, 's':saturation, 'v':value}
def hsv2rgb(H, S, V):
print "Start of hsv2rgb()"
if H == S == V == 0.0:
return {'r':0, 'g':0, 'b':0}
H *= 6
I = math.floor(H)
F = H - I
M = V * (1 - S)
N = V * (1 - S * F)
K = V * (1 - S * (1 - F))
R = G = B = 0.0
if I == 0:
R = V
G = K
B = M
elif I == 1:
R = N
G = V
B = M
elif I == 2:
R = M
G = V
B = K
elif I == 3:
R = M
G = N
B = V
elif I == 4:
R = K
G = M
B = V
else:
R = V
G = M
B = N
red = to8bit(R)
green = to8bit(G)
blue = to8bit(B)
return {'r':red, 'g':green, 'b':blue}
The functions closely match the algorithm pseudocodes in Smith's article, and even have the same variable names.
This demo was a good learning experience in understanding the algorithms that transform between the colour models of RGB and HSV.
## 2012-10-06
### Example of Trigonometric Functions in Matplotlib
The matplotlib library offers excellent functionality for quick and simple graphing capabilities in python.
Excellent tutorials exist about how to use matplotlib for common graphing tasks. The matplotlib documentation of scipy by Mike Müller and the Matplotlib Tutorial by Nicolas P. Rougier offer excellent code snippets that illustrate simple graphing in matplotlib.
I especially like Rougier's "Devil is in the Details" example, which I've modelled the following example on, to show the graphs of sine, cosecant, cosine, secant, tangent, and cotangent.
Here is my spin on this, code and results below.
#!/usr/bin/python from pylab import * # rendering area figure(figsize=(8,5), dpi=80) # display area to use; can be modified to accomodate more graphs subplot(111) # range x = np.linspace(0, (2 * np.pi), 256,endpoint=True) # formulas to graph sine = np.sin(x) cosine = np.cos(x) tangent = np.tan(x) cotangent = 1/np.tan(x) cosecant = 1/np.sin(x) secant = 1/np.cos(x) # line styles and labels plot(x, sine, color="red", linewidth=2.5, linestyle="-", label="sin") plot(x, cosine, color="blue", linewidth=2.5, linestyle="-", label="cos") plot(x, tangent, color="orange", linewidth=2.5, linestyle="-", label="tan") plot(x, cotangent, color="purple", linewidth=2.5, linestyle="-", label="cot") plot(x, cosecant, color="green", linewidth=2.5, linestyle="-", label="csc") plot(x, secant, color="yellow", linewidth=2.5, linestyle="-", label="sec") # tick spines ax = gca() ax.spines['right'].set_color('none') ax.spines['top'].set_color('none') ax.xaxis.set_ticks_position('bottom') ax.spines['bottom'].set_position(('data',0)) ax.yaxis.set_ticks_position('left') ax.spines['left'].set_position(('data',0)) # x tick limits and labels xlim(x.min()*1.1, x.max()*1.1) xticks([(-2 * np.pi), (-3 * np.pi/2), -np.pi, -np.pi/2, 0, np.pi/2, np.pi, (3 * np.pi/2), (2 * np.pi)], [r'$-2\pi$', r'$-3/2\pi$', r'$-\pi$', r'$-\pi/2$', r'$0$', r'$+\pi/2$', r'$+\pi$', r'$3/2\pi$', r'$2\pi$']) # y tick limits and labels ylim(-4, 4) yticks([-4, -3, -2, -1, +1, +2, +3, +4], [r'$-4$', r'$-3$', r'$-2$', r'$-1$', r'$+1$', r'$+2$', r'$+3$', r'$+4$']) # legend legend(loc='upper left') for label in ax.get_xticklabels() + ax.get_yticklabels(): label.set_fontsize(16) label.set_bbox(dict(facecolor='white', edgecolor='None', alpha=0.65 )) # display show()
## 2012-09-14
I've been using Google Docs for several years, and recently participated in a kind of unexpected migration to Google Drive. I like the overall ease of use of the "Docs" part of Google Drive, and will hereforwards refer to this simply as "Google Docs".
I have been wanting to know for some time how to go about uploading a document to Google Docs via some kind of API. The Google Documents List API provides this functionality, and there are some useful examples on how to employ the Python version to upload files, as shown by Google here, and as seen in various postings on sites such as Stack Overflow, such as an example seen here.
Here is my version of how to upload a file to Google Docs, based on examples I mentioned above, available at http://github.com/mikequentel/google-drive-python In order to use this script, Google Documents List API version 3.0 is required, but this can be downloaded as the Google APIs Client Library for Python.
#!/usr/bin/pythonimport sysimport argparseimport osimport gdata.dataimport gdata.docs.clientimport gdata.docs.dataimport gdata.docs.serviceimport gdata.sample_utilclass SampleConfig(object): APP_NAME = 'GDataDocumentsListAPISample-v1.0' DEBUG = Falsedef create_client(): client = gdata.docs.client.DocsClient(source=SampleConfig.APP_NAME) try: gdata.sample_util.authorize_client( client, 1, service=client.auth_service, source=client.source, scopes=client.auth_scopes ) except gdata.client.BadAuthentication: exit('Invalid user credentials given.') except gdata.client.Error: exit('Login Error') return clientdef upload_file(path, title, type, do_convert): client = create_client() doc = gdata.docs.data.Resource(type=type, title=title) media = gdata.data.MediaSource() media.SetFileHandle(path, type) create_uri = gdata.docs.client.RESOURCE_UPLOAD_URI + '?convert=' + do_convert doc = client.CreateResource(doc, create_uri=create_uri, media=media) print 'Uploaded:', doc.title.text, doc.resource_id.textdef main(): parser = argparse.ArgumentParser(description='Upload file to Google Drive (previously known as \'Google Docs\').') parser.add_argument('file', help='file to upload.') parser.add_argument('title', help='title for the uploaded document.') parser.add_argument('type', nargs='?', default='text/plain', help='type of file to upload, default is text/plain.') parser.add_argument('do_convert', nargs='?', default='true', help='true or false: convert the document to Google Docs format? Default is true') args = parser.parse_args() path = args.file title = args.title type = args.type do_convert = args.do_convert upload_file(path, title, type, do_convert) os._exit(0)# Specifies name of main function.if __name__ == "__main__": sys.exit(main())
## 2012-06-26
### Using Rule of Sarrus, Cramer's Rule, and Python to Solve a System of Three Linear Equations
Lately I've been studying how to solve a system of linear equations; in particular, three linear equations. Not satisfied with the "Elimination of Variables" method for solving this sort of problem, I researched other ways of solving for x, y, and z values. I found that the Rule of Sarrus and Cramer's Rule are ideal for my purposes, and put these concepts into a Python script that would illustrate the rules.
I must mention that the code below is a fresh prototype, and lacks error-trapping at this time (for example, nothing traps for division by zero). Reason for this rough implementation is to keep the code readable as an example of using the rules of Sarrus and Cramer, rather than an actual implementation that would be used in a real system.
# System of three linear equations
# ax + by + cz = j
# dx + ey + fz = k
# gx + hy + iz = l
# System of three linear equations in matrix notation
# - - - - - -
# | a b c | | x | | j |
# | | | | | |
# | d e f | | y | = | k |
# | | | | | |
# | g h i | | z | | l |
# - - - - - -
# Matrix of Coefficients
# a b c
# d e f
# g h i
# Matrix of Variables
# x
# y
# z
# Matrix of Resulting Values
# j
# k
# l
# Rule of Sarrus
# a b c|a b
# d e f|d e
# g h i|g h
# Rule of Sarrus Index Values
# 0 1 2|0 1
# 3 4 5|3 4
# 6 7 8|6 7
# Determinant
# det(M) = aei + bfg + cdh - gec - hfa - idb
# Cramer's Rule
# | j b c | | a j c | | a b j |
# | k e f | | d k f | | d e k |
# | l h i | | g l i | | g h l |
# ---------, ---------, ---------
# | a b c | | a b c | | a b c |
# | d e f | | d e f | | d e f |
# | g h i | | g h i | | g h i |
import sys
def main():
inputs_dict = {'a':int(raw_input("a:")), 'b':int(raw_input("b:")), 'c':int(raw_input("c:")), 'j':int(raw_input("j:")),
'd':int(raw_input("d:")), 'e':int(raw_input("e:")), 'f':int(raw_input("f:")), 'k':int(raw_input("k:")),
'g':int(raw_input("g:")), 'h':int(raw_input("h:")), 'i':int(raw_input("i:")), 'l':int(raw_input("l:"))}
coeffs_matrix = {'a':inputs_dict['a'], 'b':inputs_dict['b'], 'c':inputs_dict['c'],
'd':inputs_dict['d'], 'e':inputs_dict['e'], 'f':inputs_dict['f'],
'g':inputs_dict['g'], 'h':inputs_dict['h'], 'i':inputs_dict['i']}
x_numerator_matrix = {'j':inputs_dict['j'], 'b':inputs_dict['b'], 'c':inputs_dict['c'],
'k':inputs_dict['k'], 'e':inputs_dict['e'], 'f':inputs_dict['f'],
'l':inputs_dict['l'], 'h':inputs_dict['h'], 'i':inputs_dict['i']}
y_numerator_matrix = {'a':inputs_dict['a'], 'j':inputs_dict['j'], 'c':inputs_dict['c'],
'd':inputs_dict['d'], 'k':inputs_dict['k'], 'f':inputs_dict['f'],
'g':inputs_dict['g'], 'l':inputs_dict['l'], 'i':inputs_dict['i']}
z_numerator_matrix = {'a':inputs_dict['a'], 'b':inputs_dict['b'], 'j':inputs_dict['j'],
'd':inputs_dict['d'], 'e':inputs_dict['e'], 'k':inputs_dict['k'],
'g':inputs_dict['g'], 'h':inputs_dict['h'], 'l':inputs_dict['l']}
# Rule of Sarrus for det_coeffs_matrix
# a b c|a b
# d e f|d e
# g h i|g h
#
det_coeffs_matrix = (coeffs_matrix['a'] * coeffs_matrix['e'] * coeffs_matrix['i'] +
coeffs_matrix['b'] * coeffs_matrix['f'] * coeffs_matrix['g'] +
coeffs_matrix['c'] * coeffs_matrix['d'] * coeffs_matrix['h'] -
coeffs_matrix['g'] * coeffs_matrix['e'] * coeffs_matrix['c'] -
coeffs_matrix['h'] * coeffs_matrix['f'] * coeffs_matrix['a'] -
coeffs_matrix['i'] * coeffs_matrix['d'] * coeffs_matrix['b'])
# Rule of Sarrus for det_x_numerator_matrix
# j b c|j b
# k e f|k e
# l h i|l h
#
det_x_numerator_matrix = (x_numerator_matrix['j'] * x_numerator_matrix['e'] * x_numerator_matrix['i'] +
x_numerator_matrix['b'] * x_numerator_matrix['f'] * x_numerator_matrix['l'] +
x_numerator_matrix['c'] * x_numerator_matrix['k'] * x_numerator_matrix['h'] -
x_numerator_matrix['l'] * x_numerator_matrix['e'] * x_numerator_matrix['c'] -
x_numerator_matrix['h'] * x_numerator_matrix['f'] * x_numerator_matrix['j'] -
x_numerator_matrix['i'] * x_numerator_matrix['k'] * x_numerator_matrix['b'] )
# Rule of Sarrus for det_y_numerator_matrix
# a j c|a j
# d k f|d k
# g l i|g l
#
det_y_numerator_matrix = (y_numerator_matrix['a'] * y_numerator_matrix['k'] * y_numerator_matrix['i'] +
y_numerator_matrix['j'] * y_numerator_matrix['f'] * y_numerator_matrix['g'] +
y_numerator_matrix['c'] * y_numerator_matrix['d'] * y_numerator_matrix['l'] -
y_numerator_matrix['g'] * y_numerator_matrix['k'] * y_numerator_matrix['c'] -
y_numerator_matrix['l'] * y_numerator_matrix['f'] * y_numerator_matrix['a'] -
y_numerator_matrix['i'] * y_numerator_matrix['d'] * y_numerator_matrix['j'])
# Rule of Sarrus for det_z_numerator_matrix
# a b j|a b
# d e k|d e
# g h l|g h
#
det_z_numerator_matrix = (z_numerator_matrix['a'] * z_numerator_matrix['e'] * z_numerator_matrix['l'] +
z_numerator_matrix['b'] * z_numerator_matrix['k'] * z_numerator_matrix['g'] +
z_numerator_matrix['j'] * z_numerator_matrix['d'] * z_numerator_matrix['h'] -
z_numerator_matrix['g'] * z_numerator_matrix['e'] * z_numerator_matrix['j'] -
z_numerator_matrix['h'] * z_numerator_matrix['k'] * z_numerator_matrix['a'] -
z_numerator_matrix['l'] * z_numerator_matrix['d'] * z_numerator_matrix['b'])
x = det_x_numerator_matrix/det_coeffs_matrix
y = det_y_numerator_matrix/det_coeffs_matrix
z = det_z_numerator_matrix/det_coeffs_matrix
print
print "results: "
print "x = " + str(x)
print "y = " + str(y)
print "z = " + str(z)
# Specifies name of main function.
if __name__ == "__main__":
sys.exit(main())
## 2010-11-14
### How to Create a Text File List of RGB Values in C
Here is a very simple C program for generating RGB values listed in a text file:
#include <stdio.h>
int main() {
FILE *fp;
fp = fopen("true_colour.txt", "w");
int r = 255;
int g = 255;
int b = 255;
for (r = 255; r >= 0; r--) {
for (g = 255; g >= 0; g--) {
for (b = 255; b >= 0; b--) {
fprintf(fp, "%d", r);
fprintf(fp, ",");
fprintf(fp, "%d", g);
fprintf(fp, ",");
fprintf(fp, "%d", b);
fprintf(fp, "\n");
}
}
}
fclose(fp);
return 0;
}
C source available at http://gist.github.com/mikequentel/e32acc62b3ae5e330558
Also available in Ada at http://gist.github.com/mikequentel/6bfc40638ca4a789f8e2
## 2010-09-29
### Moving Sharepoint (MOSS) from One Server to Another
Lots of information exists on the internet concerning how to backup, restore, and move Microsoft Office Sharepoint Server (MOSS). Here, I will refer to this simply as "Sharepoint". Many developers (including myself) have wondered, "what is the easiest way to fully backup and restore, and even in the process, move, Sharepoint?"...so here an easy way to do a full backup of one Sharepoint server, then restore to another Sharepoint server...
Sharepoint backup from original (source) server:
C:\Program Files\Common Files\Microsoft Shared\web server extensions\12\BIN>stsadm -o backup -url http://mysourceserver:80/ -filename C:\sharepoint_backups\myoriginalsharepointinstance.bak
Sharepoint restore to another (destination) server:
C:\Program Files\Common Files\Microsoft Shared\web server extensions\12\BIN>stsadm -o restore -url http://mydestinationserver/ -overwrite -filename C:\sharepoint_backups\myoriginalsharepointinstance.bak | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 1, "mathjax_display_tex": 0, "mathjax_asciimath": 1, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.38466882705688477, "perplexity": 12085.722622153538}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 20, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2015-48/segments/1448398451648.66/warc/CC-MAIN-20151124205411-00234-ip-10-71-132-137.ec2.internal.warc.gz"} |
https://pbs-assess.github.io/sdmTMB/reference/predict.sdmTMB.html | Can predict on the original data locations or on new data.
# S3 method for sdmTMB
predict(
object,
newdata = NULL,
se_fit = FALSE,
xy_cols = c("X", "Y"),
return_tmb_object = FALSE,
area = 1,
re_form = NULL,
...
)
## Arguments
object An object from sdmTMB(). An optional new data frame. This should be a data frame with the same predictor columns as in the fitted data and a time column (if this is a spatiotemporal model) with the same name as in the fitted data. There should be predictor data for each year in the original data set. Should standard errors on predictions at the new locations given by newdata be calculated? Warning: the current implementation can be slow for large data sets or high-resolution projections. A character vector of length 2 that gives the column names of the x and y coordinates in newdata. Logical. If TRUE, will include the TMB object in a list format output. Necessary for the get_index() or get_cog() functions. A vector of areas for survey grid cells. Only necessary if the output will be passed to get_index() or get_cog(). Should be the same length as the number of rows of newdata. If length 1, will be repeated to match the rows of data. NULL to specify individual-level predictions. ~0 or NA for population-level predictions. Note that unlike lme4 or glmmTMB, this only affects what the standard errors are calculated on if se_fit = TRUE. Otherwise, predictions at various levels are returned in all cases. Not implemented.
## Value
If return_tmb_object = FALSE: A data frame:
• est: Estimate in link space (everything is in link space)
• est_non_rf: Estimate from everything that isn't a random field
• est_rf: Estimate from all random fields combined
• omega_s: Spatial (intercept) random field that is constant through time
• zeta_s: Spatial slope random field
• epsilon_st: Spatiotemporal (intercept) random fields (could be independent draws each year or AR1)
If return_tmb_object = TRUE: A list:
• data: The data frame described above
• report: The TMB report on parameter values
• obj: The TMB object returned from the prediction run.
• fit_obj: The original TMB model object.
You likely only need the data element as an end user. The other elements are included for other functions.
## Examples
# We'll only use a small number of knots so this example runs quickly
# but you will likely want to use many more in applied situations.
library(ggplot2)
d <- pcod
pcod_spde <- make_mesh(d, c("X", "Y"), cutoff = 30) # a coarse mesh for example speed
m <- sdmTMB(
data = d, formula = density ~ 0 + as.factor(year) + depth_scaled + depth_scaled2,
time = "year", spde = pcod_spde, family = tweedie(link = "log")
)
# Predictions at original data locations -------------------------------
predictions <- predict(m)
#> year X Y depth density present lat lon
#> 888 2003 446.4752 5793.426 201 113.13848 1 52.28858 -129.7847
#> 887 2003 446.4594 5800.136 212 41.70492 1 52.34890 -129.7860
#> 921 2003 448.5987 5801.687 220 0.00000 0 52.36305 -129.7549
#> 756 2003 436.9157 5802.305 197 15.70614 1 52.36738 -129.9265
#> 521 2003 420.6101 5771.055 256 0.00000 0 52.08437 -130.1586
#> 488 2003 417.7130 5772.205 293 0.00000 0 52.09428 -130.2012
#> depth_mean depth_sd depth_scaled depth_scaled2 est est_non_rf
#> 888 5.155194 0.4448783 0.3329252 0.11083919 3.45791471 3.2225314
#> 887 5.155194 0.4448783 0.4526914 0.20492947 3.35694044 2.9247984
#> 921 5.155194 0.4448783 0.5359529 0.28724555 3.18090324 2.6958553
#> 756 5.155194 0.4448783 0.2877417 0.08279527 3.78707132 3.3251741
#> 521 5.155194 0.4448783 0.8766077 0.76844097 1.08926601 1.5715748
#> 488 5.155194 0.4448783 1.1800505 1.39251928 -0.08533285 0.3162215
#> est_rf omega_s zeta_s epsilon_st
#> 888 0.2353833 -0.17932670 0 0.4147100
#> 887 0.4321420 -0.07780172 0 0.5099438
#> 921 0.4850480 -0.08540468 0 0.5704527
#> 756 0.4618972 0.12196182 0 0.3399354
#> 521 -0.4823088 -0.09804612 0 -0.3842627
#> 488 -0.4015544 -0.07050750 0 -0.3310469
predictions$resids <- residuals(m) # randomized quantile residuals # \donttest{ ggplot(predictions, aes(X, Y, col = resids)) + scale_colour_gradient2() + geom_point() + facet_wrap(~year) hist(predictions$resids)
qqnorm(predictions$resids);abline(a = 0, b = 1) # Predictions onto new data -------------------------------------------- predictions <- predict(m, newdata = qcs_grid) # A short function for plotting our predictions: plot_map <- function(dat, column = "est") { ggplot(dat, aes_string("X", "Y", fill = column)) + geom_raster() + facet_wrap(~year) + coord_fixed() } plot_map(predictions, "exp(est)") + scale_fill_viridis_c(trans = "sqrt") + ggtitle("Prediction (fixed effects + all random effects)") plot_map(predictions, "exp(est_non_rf)") + ggtitle("Prediction (fixed effects and any time-varying effects)") + scale_fill_viridis_c(trans = "sqrt") plot_map(predictions, "est_rf") + ggtitle("All random field estimates") + scale_fill_gradient2() plot_map(predictions, "omega_s") + ggtitle("Spatial random effects only") + scale_fill_gradient2() plot_map(predictions, "epsilon_st") + ggtitle("Spatiotemporal random effects only") + scale_fill_gradient2() # Visualizing a marginal effect ---------------------------------------- nd <- data.frame(depth_scaled = seq(min(d$depth_scaled), max(d$depth_scaled), length.out = 100)) nd$depth_scaled2 <- nd$depth_scaled^2 # You'll need at least one time element. If time isn't also a fixed effect # then it doesn't matter what you pick: nd$year <- 2003L
p <- predict(m, newdata = nd, se_fit = TRUE, re_form = NA)
ggplot(p, aes(depth_scaled, exp(est),
ymin = exp(est - 1.96 * est_se), ymax = exp(est + 1.96 * est_se))) +
geom_line() + geom_ribbon(alpha = 0.4)
# Plotting marginal effect of a spline ---------------------------------
m_gam <- sdmTMB(
data = d, formula = density ~ 0 + as.factor(year) + s(depth_scaled, k = 3),
time = "year", spde = pcod_spde, family = tweedie(link = "log")
)
nd <- data.frame(depth_scaled =
seq(min(d$depth_scaled), max(d$depth_scaled), length.out = 100))
nd$year <- 2003L p <- predict(m_gam, newdata = nd, se_fit = TRUE, re_form = NA) ggplot(p, aes(depth_scaled, exp(est), ymin = exp(est - 1.96 * est_se), ymax = exp(est + 1.96 * est_se))) + geom_line() + geom_ribbon(alpha = 0.4) # Forecasting ---------------------------------------------------------- pcod_spde <- make_mesh(d, c("X", "Y"), cutoff = 15) unique(d$year)
#> [1] 2003 2004 2005 2007 2009 2011 2013 2015 2017m <- sdmTMB(
data = d, formula = density ~ 1,
ar1_fields = TRUE, # using an AR1 to have something to forecast with
extra_time = 2019L,
include_spatial = FALSE,
time = "year", spde = pcod_spde, family = tweedie(link = "log")
)
# Add a year to our grid:
grid2019 <- qcs_grid[qcs_grid$year == max(qcs_grid$year), ]
grid2019\$year <- 2019L # L because year is an integer in the data
qcsgrid_forecast <- rbind(qcs_grid, grid2019)
predictions <- predict(m, newdata = qcsgrid_forecast)
plot_map(predictions, "exp(est)") +
scale_fill_viridis_c(trans = "log10")
plot_map(predictions, "epsilon_st") +
# Estimating local trends ----------------------------------------------
pcod_spde <- make_mesh(pcod, c("X", "Y"), cutoff = 25)
m <- sdmTMB(data = pcod, formula = density ~ depth_scaled + depth_scaled2,
spde = pcod_spde, family = tweedie(link = "log"),
spatial_trend = TRUE, time = "year", spatial_only = TRUE)
p <- predict(m, newdata = qcs_grid)
plot_map(p, "zeta_s") +
ggtitle("Spatial slopes") +
plot_map(p, "est_rf") +
ggtitle("Random field estimates") + | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 1, "mathjax_display_tex": 0, "mathjax_asciimath": 1, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.1841684728860855, "perplexity": 12404.52140269142}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2020-50/segments/1606141706569.64/warc/CC-MAIN-20201202083021-20201202113021-00141.warc.gz"} |
http://www.mathnet.ru/php/archive.phtml?wshow=paper&jrnid=tm&paperid=3939&option_lang=eng | RUS ENG JOURNALS PEOPLE ORGANISATIONS CONFERENCES SEMINARS VIDEO LIBRARY PACKAGE AMSBIB
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Trudy MIAN: Year: Volume: Issue: Page: Find
Tr. Mat. Inst. Steklova, 2018, Volume 303, Pages 17–25 (Mi tm3939)
Selections of the best and near-best approximation operators and solarity
A. R. Alimovab
a Faculty of Mechanics and Mathematics, Moscow State University, Moscow, 119991 Russia
b Steklov Mathematical Institute of Russian Academy of Sciences, ul. Gubkina 8, Moscow, 119991 Russia
Abstract: In a finite-dimensional Banach space, a closed set with lower semicontinuous metric projection is shown to have a continuous selection of the near-best approximation operator. Such a set is known to be a sun. In the converse question of the stability of best approximation by suns, it is proved that a strict sun in a finite-dimensional Banach space of dimension at most $3$ is a $P$-sun, has a contractible set of nearest points, and admits a continuous $\varepsilon$-selection from the operator of near-best approximation for any $\varepsilon >0$. A number of approximative and geometric properties of sets with lower semicontinuous metric projection are obtained.
Funding Agency Grant Number Russian Foundation for Basic Research 18-01-00333_à19-01-00332_à Ministry of Education and Science of the Russian Federation ÍØ-6222.2018.1 The work was supported by the Russian Foundation for Basic Research (project nos. 18-01-00333 and 19-01-00332-a) and by a grant of the President of the Russian Federation (project no. NSh-6222.2018.1).
DOI: https://doi.org/10.1134/S0371968518040027
Full text: PDF file (184 kB)
First page: PDF file
References: PDF file HTML file
English version:
Proceedings of the Steklov Institute of Mathematics, 2018, 303, 10–17
Bibliographic databases:
UDC: 517.982.256+517.982.252
Citation: A. R. Alimov, “Selections of the best and near-best approximation operators and solarity”, Harmonic analysis, approximation theory, and number theory, Collected papers. Dedicated to Academician Sergei Vladimirovich Konyagin on the occasion of his 60th birthday, Tr. Mat. Inst. Steklova, 303, MAIK Nauka/Interperiodica, Moscow, 2018, 17–25; Proc. Steklov Inst. Math., 303 (2018), 10–17
Citation in format AMSBIB
\Bibitem{Ali18} \by A.~R.~Alimov \paper Selections of the best and near-best approximation operators and solarity \inbook Harmonic analysis, approximation theory, and number theory \bookinfo Collected papers. Dedicated to Academician Sergei Vladimirovich Konyagin on the occasion of his 60th birthday \serial Tr. Mat. Inst. Steklova \yr 2018 \vol 303 \pages 17--25 \publ MAIK Nauka/Interperiodica \publaddr Moscow \mathnet{http://mi.mathnet.ru/tm3939} \crossref{https://doi.org/10.1134/S0371968518040027} \elib{http://elibrary.ru/item.asp?id=37045248} \transl \jour Proc. Steklov Inst. Math. \yr 2018 \vol 303 \pages 10--17 \crossref{https://doi.org/10.1134/S0081543818080023} \isi{http://gateway.isiknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&DestLinkType=FullRecord&DestApp=ALL_WOS&KeyUT=000460475900002} \scopus{http://www.scopus.com/record/display.url?origin=inward&eid=2-s2.0-85062548173}
• http://mi.mathnet.ru/eng/tm3939
• https://doi.org/10.1134/S0371968518040027
• http://mi.mathnet.ru/eng/tm/v303/p17
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Citing articles on Google Scholar: Russian citations, English citations
Related articles on Google Scholar: Russian articles, English articles
This publication is cited in the following articles:
1. Alimov A.R., “Solarity of Sets in Max-Approximation Problems”, J. Fixed Point Theory Appl., 21:3 (2019), UNSP 76
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https://into.ai/blog/news-stories/measuring-quantum-entanglement-machine-learning-and-wave-function-tomography/ | Select Page
Measuring quantum entanglement, machine learning and wave function tomography
There is an enormous amount of information that can be extracted from thedata of a quantum gas microscope that has yet to be fully explored. The quantumgas microscope has been used to directly measure magnetic order, dynamiccorrelations, Pauli blocking, and many other physical phenomena in severalrecent groundbreaking experiments. However, the analysis of the data from aquantum gas microscope can be pushed much further, and when used in conjunctionwith theoretical constructs it is possible to measure virtually any observableof interest in a wide range of systems. We focus on how to measure quantumentanglement in large interacting quantum systems. In particular, we show thatquantum gas microscopes can be used to measure the entanglement of interactingboson systems exactly, where previously it had been thought this was onlypossible for non-interacting systems. We consider algorithms…
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Jun 15 awarded Nice Answer Jun 6 awarded Notable Question Mar 22 reviewed Leave Closed How to prove the monotonicity of the following function with respect to $\alpha$? Mar 22 revised Evaluating Difficult Monte Carlo Integration in R another approach Mar 22 revised Monte Carlo gamma function added better approach Mar 22 revised Monte Carlo gamma function removed statement Mar 22 revised Evaluating Difficult Monte Carlo Integration in R grammar Mar 22 revised Monte Carlo gamma function another approach Mar 22 revised Evaluating Difficult Monte Carlo Integration in R added second method Mar 22 reviewed Reopen How to represent the member of generated sigma algebra in terms of unions and complements? Mar 22 reviewed Reopen Writing a partial sum of Fourier series as an integral Mar 22 revised Monte Carlo gamma function clarification Mar 22 revised Evaluating Difficult Monte Carlo Integration in R Clarification Mar 22 answered Evaluating Difficult Monte Carlo Integration in R Mar 22 revised Evaluating Difficult Monte Carlo Integration in R formatting Mar 22 comment Least squares fit to a an exponential equation with one unknown @oorst: Can you post all of the details or is it too much data? Mar 22 revised Monte Carlo gamma function more cleanup Mar 22 answered Monte Carlo gamma function Mar 22 revised Integration (Trapezium Rule) formatting Mar 22 revised Integration (Trapezium Rule) formatting | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 1, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.9838922023773193, "perplexity": 2715.4644323803714}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2015-35/segments/1440645257890.57/warc/CC-MAIN-20150827031417-00043-ip-10-171-96-226.ec2.internal.warc.gz"} |
https://procake.pages.gitlab.rlp.net/procake-wiki/sim/intervals/ | Intervals
# Interval #
The data types in the query and in the case are intervals. We name the query interval $$x_i = [x_{ilb},x_{iub}]$$ , the case interval $$y_i = [y_{ilb},y_{iub}]$$ , and a possible intersection $$z_i = [z_{ilb},z_{iub}]$$ , each defined by a lower bound and an upper bound. The calculation of the similarity between two intervals does not only depend on the intervals themselves, but also on a given local similarity measure $$sim_{Ai}$$ . This local similarity measure could, for instance, be the numeric linear measure.
The interval in the case can be interpreted in a way that a valid value exists in this range, but it is not sure where it is. It can’t be assumed that valid values are in the intersection of query and case interval. Therefore, three strategies must be distinguished:
• The optimistic strategy assumes that valid points are in the intersection. With the imprecise query, one point is requested from all the possible points of the precise case. Therefore, we just have to distinguish the following two situations: $$z_i =\not \emptyset$$ : The local similarity is one, because an arbitrary element of $$z_i$$ or $$z_i$$ itself can be returned. In other words, the maximum similarity is returned because there is some kind of intersection.
• $$z_i = \emptyset$$ : The local similarity must consider the distance from $$x_{ilb}$$ to $$y_{iub}$$ and $$x_{iub}$$ to $$y_{ilb}$$ , so that $$sim^*_{Ai}(x_i,y_i) = \max\left(sim_{Ai}(x_{ilb},y_{iub}), sim_{Ai}(x_{iub},y_{ilb})\right)$$ . Thereby, the similarity decreases with an increasing distance between query and case intervals.
• Summarizing, a local similarity measure can be defined as:
• $$sim^*_{Ai}(x_i, y_i) = \begin{cases} \qquad \qquad \quad 1 &\text{, if } z_i =\not \emptyset \\max\begin{pmatrix} sim_{Ai}(x_{ilb}, y_{iub}), \\ sim_{Ai}(x_{iub}, y_{ilb})\end{pmatrix} & , otherwise\end{cases}$$
• The pessimistic strategy assumes that no valid point is in the intersection which leads to the local similarity:
$$sim^*_{Ai}(x_i, y_i) = \underset{\forall x_{is}\in x_i, y_{it}\in y_i}{min}\{sim_{Ai}(x_{is},y_{it})\}$$
• The average strategy calculates the probability that a valid point is in the intersection $$z_i$$ , e.g. by calculating the relation between the intersection size and the case interval size. Consequently, the similarity measure is defined as:
$$sim^*_{Ai}(x_i, y_i) = \begin{cases} \frac{|y_{iub}-y_{ilb}|}{|z_{iub}-z_{ilb}|} &\text{, if } z_i =\not \emptyset \\ 0 &, otherwise \end{cases}$$
For example, using this measure on the intervals $$Q = [0,2]$$ and $$C = [1,3]$$ , the intersection is $$z = [1,2]$$ . Using the optimistic strategy, the similarity is 1.0, because there is an intersection. Using the pessimistic strategy, the lowest similarity value between all points of both intervals is taken. In this example, a Numeric Linear measure is used, with min = 0 and max = 5. The lowest similarity is $$sim_{Ai}(0,3) = 0.4$$ , so this value is returned. Using the average strategy, the similarity is computed as $$sim_{Ai}(\frac{3-1}{2-1}) = 2$$ , so the similarity is 1.0.
Using this measure on the intervals $$Q = [0,1]$$ and $$C = [2,3]$$ , there is no intersection. Using the optimistic strategy, the NumericLinear measure from above is used. So, the following similarities are computed: $$sim_{Ai}(x_{ilb}, y_{iub} = sim_{Ai}(0,3) = 0.4$$ and $$sim_{Ai}(x_{iub}, y_{ilb}) = sim_{Ai}(1,2) = 0.8$$ . So, the maximum value 0.8 is chosen and returned as overall similarity. Using the pessimistic strategy and also the NumericLinear measure, the similarity is $$sim_{Ai}(0,3) = 0.4$$ . Using the average strategy, the similarity is 0.0, because there is no intersection.
The following parameters can be set for this similarity measure.
Parameter Type Default Value Description
strategy Strategy (String) optimistic The parameter is used to set the strategy for the similarity computation. The interval in the case can be interpreted in a way that a valid value exists in this range, but it is not sure where it is. It can’t be assumed that valid values are in the intersection of query and case interval. Therefore, the three strategies optimistic, pessimistic and average can be used.
This measure can be defined in the similarity model like below:
<Interval name="SMInterval" class="IntervalDataClass" strategy="optimistic"/>
Here, the class IntervalDataClass must refer to a Interval class. Instead of optimistic also average and pessimistic can be chosen as strategies.
SMIntervalImpl smInterval = (SMIntervalImpl) simVal.getSimilarityModel().createSimilarityMeasure(SMInterval.NAME, ModelFactory.getDefaultModel().getIntervalSystemClass());
smInterval.setDataClass(ModelFactory.getDefaultModel().getClass("IntervalDataClass"));
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http://www.mitpress.mit.edu/books/illicit-trade-and-global-economy | Hardcover | $35.00 Short | £24.95 | ISBN: 9780262016551 | 280 pp. | 6 x 9 in | 47 figures, 41 tables| December 2011 ebook |$25.00 Short | ISBN: 9780262299589 | 280 pp. | 6 x 9 in | 47 figures, 41 tables| December 2011
# Illicit Trade and the Global Economy
## Overview
As international trade has expanded dramatically in the postwar period--an expansion accelerated by the opening of China, Russia, India, and Eastern Europe--illicit international trade has grown in tandem with it. This volume uses the economist’s toolkit to examine the economic, political, and social problems resulting from such illicit activities as illegal drug trade, smuggling, and organized crime.
The contributors consider several aspects of the illegal drug market, including the sometimes puzzling relationships among purity, price, and risk; the effect of globalization on the heroin and cocaine markets, examined both through mathematical models and with empirical data from the U.K; the spread of khat, a psychoactive drug imported legally to the U.K. as a vegetable; and the economic effect of the “war on drugs” on producer and consumer countries. Other chapters examine the hidden financial flows of organized crime, patterns of smuggling in international trade, Iran’s illicit trading activity, and the impact of mafia-like crime on foreign direct investment in Italy. | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 1, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.21625691652297974, "perplexity": 12312.929886007027}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2015-06/segments/1422115865010.11/warc/CC-MAIN-20150124161105-00016-ip-10-180-212-252.ec2.internal.warc.gz"} |
http://math-mprf.org/journal/articles/id1204/ | Hyperbolic Scaling Limits: The Method of Compensated Compactness
#### J. Fritz
2010, v.16, №1, 117-138
ABSTRACT
Hydrodynamic limit of various models with hyperbolic (Euler) scaling law is discussed, we are mainly interested in the limiting behavior of the microscopic systems in a regime of shocks. In the absence of an effective coupling anadvanced method of PDE theory: compensated compactness is required. We consider some deterministic and Ginzburg - Landau models of classical statistical mechanics; the proof of several recent results is outlined. Microscopic systems living on the infinite line are preferred.
Keywords: interacting exclusions,hyperbolic scaling,Lax entropy pairs,compensated compactness,logarithmic Sobolev inequalities,relaxation schemes | {"extraction_info": {"found_math": false, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.9204293489456177, "perplexity": 2234.967120885547}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2017-17/segments/1492917119995.14/warc/CC-MAIN-20170423031159-00407-ip-10-145-167-34.ec2.internal.warc.gz"} |
https://sydney.edu.au/courses/units-of-study/2019/elec/elec9703.html | Unit of study_
# Fundamentals of Elec and Electronic Eng - ELEC9703
This unit of study aims to develop knowledge of the fundamental concepts and building blocks of electrical and electronics circuits. This is a foundation unit in circuit theory. Circuit theory is the electrical engineer's fundamental tool. The concepts learnt in this unit will be made use of heavily in many units of study (in later years) in the areas of electronics, instrumentation, electrical machines, power systems, communication systems, and signal processing. Topics: a) Basic electrical and electronic circuit concepts: Circuits, circuit elements, circuit laws, node and mesh analysis, circuit theorems, energy storage, capacitors and inductors, circuits with switches, transient response, sine waves and complex analysis, phasors, impedance, ac power. ; b) Project management, teamwork, ethics; c) Safety issues
Classes
Lectures, Laboratories, Tutorials
Assessment
Through semester assessment (40%) and Final Exam (60%)
Assumed knowledge
Basic knowledge of differentiation & integration, and HSC Physics
Prohibitions
ELEC5710 OR ELEC1103
### Details
Faculty: Engineering and Information Technologies
Semester 1
25 Feb 2019
Department/School: Electrical and Information Engineering
Study Mode: Normal (lecture/lab/tutorial) day
Census Date: 31 Mar 2019 | {"extraction_info": {"found_math": false, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.849256157875061, "perplexity": 9134.41299939185}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2019-43/segments/1570986668994.39/warc/CC-MAIN-20191016135759-20191016163259-00052.warc.gz"} |
http://www.contrib.andrew.cmu.edu/~ryanod/?p=1437 | # §9.2: Small subsets of the hypercube are noise-sensitive
An immediate consequence of the Bonami Lemma is that for any $f : \{-1,1\}^n \to {\mathbb R}$ and $k \in {\mathbb N}$, $$\label{eqn:2-4-hypercon-k} \|\mathrm{T}_{1/\sqrt{3}} f^{=k}\|_4 = \tfrac{1}{\sqrt{3}^k} \|f^{=k}\|_4 \leq \|f^{=k}\|_2.$$
This is a special case of the $(2,4)$-Hypercontractivity Theorem (whose name will be explained shortly), which says that the assumption of degree-$k$ homogeneity is not necessary:
$\mathbf{(2,4)}$-Hypercontractivity Theorem Let $f : \{-1,1\}^n \to {\mathbb R}$. Then $\|\mathrm{T}_{1/\sqrt{3}} f\|_4 \leq \|f\|_2.$
It almost looks as though you could prove this theorem simply by summing \eqref{eqn:2-4-hypercon-k} over $k$. In fact that proof strategy can be made to work given a few extra tricks (see the exercises), but it’s just as easy to repeat the induction technique used for the Bonami Lemma.
Proof of the $(2,4)$-Hypercontractivity Theorem: We’ll prove $\mathop{\bf E}[\mathrm{T}_{1/\sqrt{3}} f({\boldsymbol{x}})^4] \leq \mathop{\bf E}[f({\boldsymbol{x}})^2]^2$ using the same induction as in the Bonami Lemma. Retaining the notation $\boldsymbol{d}$ and $\boldsymbol{e}$, and using the shorthand $\mathrm{T} = \mathrm{T}_{1/\sqrt{3}}$, we have $\mathrm{T} \boldsymbol{f} = {\boldsymbol{x}}_n \cdot \tfrac{1}{\sqrt{3}} \mathrm{T} \boldsymbol{d} + \mathrm{T} \boldsymbol{e}.$ Similar computations to those in the Bonami Lemma proof yield \begin{align*} \mathop{\bf E}[(\mathrm{T} \boldsymbol{f})^4] &= \bigl(\tfrac{1}{\sqrt{3}}\bigr)^4\mathop{\bf E}[(\mathrm{T} \boldsymbol{d})^4] + 6 \bigl(\tfrac{1}{\sqrt{3}}\bigr)^2 \mathop{\bf E}[(\mathrm{T} \boldsymbol{d})^2(\mathrm{T} \boldsymbol{e})^2] + \mathop{\bf E}[(\mathrm{T} \boldsymbol{e})^4] \\ &\leq \mathop{\bf E}[(\mathrm{T} \boldsymbol{d})^4] + 2 \mathop{\bf E}[(\mathrm{T} \boldsymbol{d})^2(\mathrm{T} \boldsymbol{e})^2] + \mathop{\bf E}[(\mathrm{T} \boldsymbol{e})^4] \\ &\leq \mathop{\bf E}[(\mathrm{T} \boldsymbol{d})^4] + 2 \sqrt{\mathop{\bf E}[(\mathrm{T} \boldsymbol{d})^4]}\sqrt{\mathop{\bf E}[(\mathrm{T} \boldsymbol{e})^4]} + \mathop{\bf E}[(\mathrm{T} \boldsymbol{e})^4] \\ &\leq \mathop{\bf E}[\boldsymbol{d}^2]^2 + 2 \mathop{\bf E}[\boldsymbol{d}^2]\mathop{\bf E}[\boldsymbol{e}^2] + \mathop{\bf E}[\boldsymbol{e}^2]^2 \\ &= \bigl(\mathop{\bf E}[\boldsymbol{d}^2] + \mathop{\bf E}[\boldsymbol{e}^2]\bigr)^2 = \mathop{\bf E}[\boldsymbol{f}^2]^2, \end{align*} where the second inequality is Cauchy–Schwarz, the third is induction, and the final equality is a simple computation analogous to equation (2) in the proof of the Bonami Lemma. $\Box$
The name “hypercontractivity” in this theorem describes the fact that not only is $\mathrm{T}_{1/\sqrt{3}}$ a “contraction” on $L^2(\{-1,1\}^n)$ — meaning $\|\mathrm{T}_{1/\sqrt{3}} f\|_2 \leq \|f\|_2$ for all $f$ — it’s even a contraction when viewed as an operator from $L^2(\{-1,1\}^n)$ to $L^4(\{-1,1\}^n)$. You should think of hypercontractivity theorems as quantifying the extent to which $\mathrm{T}_\rho$ is a “smoothing”, or “reasonable-izing” operator.
Unfortunately the quantity $\|\mathrm{T}_{1/\sqrt{3}}f\|_4$ in the $(2,4)$-Hypercontractivity Theorem does not have an obvious combinatorial meaning. On the other hand, the quantity $\|\mathrm{T}_{1/\sqrt{3}}f\|_2 = \sqrt{\langle \mathrm{T}_{1/\sqrt{3}}f, \mathrm{T}_{1/\sqrt{3}}f \rangle} = \sqrt{\langle f, \mathrm{T}_{1/\sqrt{3}} \mathrm{T}_{1/\sqrt{3}} f\rangle} = \sqrt{\mathbf{Stab}_{1/3}[f]},$ does have a nice combinatorial meaning. And we can make this quantity appear in the Hypercontractivity Theorem via a simple trick from analysis, just using the fact that $\mathrm{T}_{1/\sqrt{3}}$ is a self-adjoint operator. We “flip the norms across $2$” using Hölder’s inequality:
$\mathbf{(4/3,2)}$-Hypercontractivity Theorem Let $f : \{-1,1\}^n \to {\mathbb R}$. Then $\|\mathrm{T}_{1/\sqrt{3}} f\|_2 \leq \|f\|_{4/3};$ i.e., $$\label{eqn:4/3-2} \mathbf{Stab}_{1/3}[f] \leq \|f\|_{4/3}^2.$$
Proof: Writing $\mathrm{T} = \mathrm{T}_{1/\sqrt{3}}$ for brevity we have $$\label{eqn:hc-holder} \|\mathrm{T} f\|_2^2 = \langle \mathrm{T} f, \mathrm{T} f \rangle = \langle f, \mathrm{T} \mathrm{T} f \rangle \leq \|f\|_{4/3} \|\mathrm{T} \mathrm{T} f\|_4 \leq \|f\|_{4/3} \|\mathrm{T} f\|_2$$ by Hölder’s inequality and the $(2,4)$-Hypercontractivity Theorem. Dividing through by $\|\mathrm{T} f\|_2$ (which we may assume is nonzero) completes the proof. $\Box$
In the inequality \eqref{eqn:4/3-2} the left-hand side is a natural quantity. The right-hand side is just $1$ when $f : \{-1,1\}^n \to \{-1,1\}$, which is not very interesting. But if we instead look at $f : \{-1,1\}^n \to \{0,1\}$ we get something very interesting:
Corollary 8 Let $A \subseteq \{-1,1\}^n$ have volume $\alpha$; i.e., let $1_A : \{-1,1\}^n \to \{0,1\}$ satisfy $\mathop{\bf E}[1_A] = \alpha$. Then $\mathbf{Stab}_{1/3}[1_A] = \mathop{\bf Pr}_{\substack{{\boldsymbol{x}} \sim \{-1,1\}^n \\ \boldsymbol{y} \sim N_{1/3}({\boldsymbol{x}})}}[{\boldsymbol{x}} \in A, \boldsymbol{y} \in A] \leq \alpha^{3/2}.$ Equivalently (for $\alpha > 0$), $\mathop{\bf Pr}_{\substack{{\boldsymbol{x}} \sim A \\ \boldsymbol{y} \sim N_{1/3}({\boldsymbol{x}})}}[\boldsymbol{y} \in A] \leq \alpha^{1/2}.$
Proof: This is immediate from inequality \eqref{eqn:4/3-2}, since $\|1_A\|_{4/3}^2 = \Bigr(\mathop{\bf E}_{{\boldsymbol{x}}}[|1_A({\boldsymbol{x}})|^{4/3}]^{3/4}\Bigr)^2 = \mathop{\bf E}_{{\boldsymbol{x}}}[1_A({\boldsymbol{x}})]^{3/2} = \alpha^{3/2}. \qquad \Box$
See Section 5 of this chapter for the generalization of this corollary to noise rates other than $1/3$.
Example 9 Assume $\alpha = 2^{-k}$, $k \in {\mathbb N}^+$, and $A$ is a subcube of codimension $k$; e.g., $1_A : {\mathbb F}_2^n \to \{0,1\}$ is the logical $\mathrm{AND}$ function on the first $k$ coordinates. For every $x \in A$, when we form $\boldsymbol{y} \sim N_{1/3}(x)$ we’ll have $\boldsymbol{y} \in A$ if and only if the first $k$ coordinates of $x$ do not change, which happens with probability $(2/3)^k = (2/3)^{\log(1/\alpha)} = \alpha^{\log(3/2)} \approx \alpha^{.585} \leq \alpha^{1/2}$. In fact, the bound $\alpha^{1/2}$ in Corollary 8 is essentially sharp when $A$ is a Hamming ball; see the exercises.
We can phrase Corollary 8 in terms of the expansion in a certain graph:
Definition 10 For $n \in {\mathbb N}^+$ and $\rho \in [-1,1]$, the $n$-dimensional $\rho$-stable hypercube graph is the edge-weighted, complete directed graph on vertex set $\{-1,1\}^n$ in which the weight on directed edge $(x,y) \in \{-1,1\}^n \times \{-1,1\}^n$ is equal to $\mathop{\bf Pr}[({\boldsymbol{x}},\boldsymbol{y}) = (x,y)]$ when $({\boldsymbol{x}},\boldsymbol{y})$ is a $\rho$-correlated pair. If $\rho = 1-2\delta$ for $\delta \in [0,1]$, we also call this the $\delta$-noisy hypercube graph. Here the weight on $(x,y)$ is $\mathop{\bf Pr}[({\boldsymbol{x}}, \boldsymbol{y}) = (x,y)]$ where ${\boldsymbol{x}} \sim \{-1,1\}^n$ is uniform and $\boldsymbol{y}$ is formed from ${\boldsymbol{x}}$ by negating each coordinate independently with probability $\delta$.
Remark 11 The edge weights in this graph are nonnegative and sum to $1$. The graph is also “regular” in the sense that for each $x \in \{-1,1\}^n$ the sum of all the edge weight leaving (or entering) $x$ is $2^{-n}$. You can also consider the graph to be undirected, since the weight on $(x,y)$ is the same as the weight on $(y,x)$; in this viewpoint, the weight on the undirected edge $(x,y)$ would be $2^{1-n}\delta^{\Delta(x,y)}(1-\delta)^{n-\Delta(x,y)}$. In fact, the graph is perhaps best thought of as the discrete-time Markov chain on state space $\{-1,1\}^n$ in which a step from state $x \in \{-1,1\}^n$ consists of moving to state $\boldsymbol{y} \sim N_\rho(x)$. This is a reversible chain with the uniform stationary distribution. Each discrete step is equivalent to running the “usual” continuous-time Markov chain on the hypercube for time $t = \ln(1/\rho)$ (assuming $\rho \in [0,1]$).
With this definition in place, we can see Corollary 8 as saying that the $1/3$-stable (equivalently, $1/3$-noisy) hypercube graph is a “small-set expander”: given any small $\alpha$-fraction of the vertices $A$, almost all of the edge weight touching $A$ is on its boundary. More precisely, if we choose a random vertex ${\boldsymbol{x}} \in A$ and take a random edge out of ${\boldsymbol{x}}$ (with probability proportional to its edge weight), we end up outside $A$ with probability at least $1 – \alpha^{1/2}$. You can compare this with the discussion surrounding the Level-$1$ Inequality in Chapter 5.4, which is the analogous statement for the $\rho$-stable hypercube graph “in the limit $\rho \to 0^+$”. The appropriate statement for general $\rho$ is appears in Section 5 of this chapter as the “Small-Set Expansion Theorem”.
Corollary 8 would apply equally well if $1_A$ were replaced by a function $g : \{-1,1\}^n \to \{-1,0,1\}$, with $\alpha$ denoting $\mathop{\bf Pr}[g \neq 0] = \mathop{\bf E}[|g|] = \mathop{\bf E}[g^2]$. This situation occurs naturally when $g = \mathrm{D}_i f$ for some boolean-valued $f : \{-1,1\}^n \to \{-1,1\}$. In this case $\mathbf{Stab}_{1/3}[g] = \mathbf{Inf}^{(1/3)}_i[f]$, the $1/3$-stable influence of $i$ on $f$. We conclude that for a boolean-valued function, if the influence of $i$ is small then its $1/3$-stable influence is much smaller:
Corollary 12 Let $f : \{-1,1\}^n \to \{-1,1\}$. Then $\mathbf{Inf}_i^{(1/3)}[f] \leq \mathbf{Inf}_i[f]^{3/2}$ for all $i$.
We remark that the famous KKL Theorem (stated in Chapter 4.2) more or less follows by summing the above inequality over $i \in [n]$; we could now prove it quite easily in a paragraph or so.
Let’s take one more look at the “small-set expansion result”, Corollary 8. Since noise stability roughly measures how “low” a function’s Fourier weight is, this corollary implies that a function $f : \{-1,1\}^n \to \{0,1\}$ with small mean $\alpha$ cannot have much of its Fourier weight at low degree. More precisely, for any $k \in {\mathbb N}$ we have $$\label{eqn:weak-level-k} \alpha^{3/2} \geq \mathbf{Stab}_{1/3}[f] \geq (1/3)^k \mathbf{W}^{\leq k}[f] \quad\Rightarrow\quad \mathbf{W}^{\leq k}[f] \leq 3^k \alpha^{3/2}.$$ For $k = 1$ this gives $\mathbf{W}^{\leq 1}[f] \leq 3\alpha^{3/2}$, which is nontrivial but not as strong as the Level-1 Inequality from Chapter 5.4. But \eqref{eqn:weak-level-k} also gives us “level-$k$ inequalities” for larger values of $k$. For example, $\mathbf{W}^{\leq .25 \log(1/\alpha)}[f] \leq \alpha^{-.25 \log 3 + 3/2} \leq \alpha^{1.1} \ll \alpha = \|f\|_2^2;$ i.e., almost all of $f$’s Fourier weight is above degree $.25 \log(1/\alpha)$. We will give slightly improved versions of these level-$k$ inequalities in Section 5 of this chapter.
### 2 comments to §9.2: Small subsets of the hypercube are noise-sensitive
• Mitchell Johnston
Hi Ryan,
For the equations in the (2,4) theorem you leave the Ts in when you apply the induction hypothesis which gives you the wrong result in the end.
Best,
Mitchell
• Thanks Mitchell — that was a big mistake! I think it’s fixed now. | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 2, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 4, "x-ck12": 0, "texerror": 0, "math_score": 0.994691789150238, "perplexity": 365.81962307066647}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2016-18/segments/1461861718132.40/warc/CC-MAIN-20160428164158-00049-ip-10-239-7-51.ec2.internal.warc.gz"} |
https://sites.google.com/site/shyunseo/ | ### 서승현(徐承鉉)
Associate Professor Department of Mathematics Education 1 KNU-Ave, Chuncheon, 200-701 Korea Tel: +82-33-250-6721 Fax: +82-33-259-5599 E-mail: shyunseo (AT) kangwon (dot) ac (dot) krTeaching: 2015 springTopology 1Topics in algebraDiscrete MathematicsResearch AreaEnumerative CombinatoricsAlgebraic CombinatoricsEducation 2004, Ph. D. Dept. of Mathematics, KAIST (advisor: Dongsu Kim) 1998, M. S. Dept. of Mathematics, KAIST 1996, B. S. Dept. of Mathematics Education, Seoul National University Employment2012-present, Associate Professor, Department of Mathematics Education, Kangwon National University2008-2012, Assistant Professor, Department of Mathematics Education, Kangwon National University2007-2008, Lecturer, Department of Mathematics Education, Cheongju University 2005-2007, Instructor, Department of Mathematics, Seoul National UniversityVisiting Position2004-2005, Visiting Scholar, Department of Mathematics, Brandeis University (mentor: Ira Gessel)PublicationsSigned a-polynomials of graphs and Poincaré polynomials of real toric manifolds (with Heesung Shin), Bulletin of Korean Mathematical Society 52(2) (2015), 467-481.Annular noncrossing permutations and minimal transitive factorizations (with Jang Soo Kim and Heesung Shin), Journal of Combinatorial Theory, series A 124(2014), 251-262.Shi-threshold arrangements, Electronic Journal of Combinatorics 19(3) (2012), P39.Enumeration of 0/1-matrices avoiding some 2x2 matrices (with Hyeong-Kwan Ju), Discrete Mathematics 312(16) (2012), 2473-2481.A refinement for ordered labeled trees (with Heesung Shin), Korean Journal of Mathematics 20(2) (2012), 255-261. On the enumeration of rooted trees with fixed size of maximal decreasing trees (with Heesung Shin), Discrete Mathematics 312(2) (2012), 419-426.Combinatorial proofs of inverse relations and log-concavity for Bessel numbers (with Hyuk Han), European Journal of Combinatorics 29(2008), 1544-1554. A Generalized enumeration of labeled trees and reverse Prüfer algorithm (with Heesung Shin), Journal of Combinatorial Theory, series A 114 (2007), 1357-1361. An efficient top-down search algorithm for learning Boolean networks of gene expression (with Dougu Nam, Sangsoo Kim), Machine Learning 65(1) (2006), 229-245. A refinement of Cayley's formula for trees (with Ira Gessel), Electronic Journal of Combinatorics 11(2) (2006), R27. A combinatorial proof of Postnikov's identity and a generalized enumeration of labeled trees, Electronic Journal of Combinatorics 11(2) (2005), N3. Colored Prüfer codes for k-edge colored trees (with Manwon Cho et al), Electronic Journal of Combinatorics 11(1) (2004), N10. Transitive cycle factorizations and prime parking functions (with Dongsu Kim), Journal of Combinatorial Theory, series A 104 (2003), 125-135. | {"extraction_info": {"found_math": false, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.8564478158950806, "perplexity": 11643.364011196152}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2016-50/segments/1480698541883.3/warc/CC-MAIN-20161202170901-00376-ip-10-31-129-80.ec2.internal.warc.gz"} |
https://modelassist.epixanalytics.com/pages/diffpagesbyversion.action?pageId=1147781&selectedPageVersions=11&selectedPageVersions=12 | # Page History
## Key
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Consider a group on M individual items, D of which have a certain characteristic. Randomly picking n items from this group without replacement, where each of the M items has the same probability of being selected, is a hypergeometric process. For an example, imagine we have a bag of seven balls, three of which are red, the other four are blue. What is the probability that a person will select two red balls from the bag if he randomly picks three balls out without replacement?
First of all, we note that the probability of the second ball picked being red depends on the color of the first picked ball. If the first ball was red (with probability 3/7), there would only be two red balls left of the six balls remaining. The probability of the second ball being red, given the first ball was red, is therefore 2/6 = 1/3. However, each ball remaining in the bag has the same probability of being picked which means that each event resulting in x red balls being selected in total has the same probability. We thus need only consider the different combinations of events that are possible. There are
LaTeX Math Inline
body \left( \begin{array}{c} 7 \\ 3 \end{array} \right)
= 35 different possible ways that one can get select three items from seven. There are
LaTeX Math Inline
body \left( \begin{array}{c} 3 \\ 2 \end{array} \right)
=3 way to select two red balls from the three in the bag, and there are
LaTeX Math Inline
body \left( \begin{array}{c} 4 \\ 1 \end{array} \right)
= 4 ways to select one blue ball from the four in the bag. Thus, out of the 35 ways we could have picked three balls from the group of seven, only
LaTeX Math Inline
body \left( \begin{array}{c} 3 \\ 2 \end{array} \right)
LaTeX Math Inline
body \left( \begin{array}{c} 4 \\ 1 \end{array} \right)
=3*4 = 12 of those ways would give us two red balls. Thus, the probability of the selecting two red balls is 12/35 = 34.29%.
In general, for a population size M of which D have the characteristic of interest, in selecting a sample of size n from that population at random without replacement, the probability of observing x in with the characteristic of interest is given by:
LaTeX Math Inline
body p(x)=\frac{\left( \begin{array}{c} D \\ x \end{array} \right) \left( \begin{array}{c} M-D \\ n-x \end{array} \right)}{\left( \begin{array}{c} M \\ n \end{array} \right) }
LaTeX Math Inline
body 0\leq x\leq n
,
LaTeX Math Inline
body x \leq D
,
LaTeX Math Inline
body n \leq M
which is the probability mass function of the Hypergeometric distribution Hypergeometric(D/M,n,M). If you are curious, the Hypergeometric distribution gets its name because its probabilities are successive terms in a Gaussian hypergeometric series.
Binomial approximation to the Hypergeometric
If we replaced each item one at a time back into the population when taking our sample n, the probability of each individual item having the characteristic of interest is D/M and the number of times we sampled from D is then given by a Binomial(D/M,n). More usefully, if M is very large compared to n, the chance of picking the same item more than once if one was to replace the item after each selection would be very small. Thus, for large M (usually n<0.1M is quoted as being a satisfactory condition), there will be little difference in our sampling result whether we sample with or without replacement, and we can approximate a Hypergeometric(D/M,n,M) with a Binomial(D/M,n), which is much easier to calculate. This is explained in more detail in the section binomial approximation to the hypergeometric.
Multivariate Hypergeometric distribution
The Hypergeometric distribution can be extended to situations where there are more than two types of items in the population (i.e. more than D of one type and (M-D) of another). The probability of getting s1 from D1, s2 from D2 , etc. all in the sample n is given by:
LaTeX Math Block
alignment left
p(s_1,s_2, \dots {s_k})=\frac{\left(
\begin{array}{c}
D_1 \\
s_1
\end{array}
\right)
\left(
\begin{array}{c}
D_2 \\
s_2
\end{array}
\right)
\dots
\left(
\begin{array}{c}
D_k \\
s_k
\end{array}
\right)
}{\left(
\begin{array}{c}
M \\
n
\end{array}
\right)}
where
LaTeX Math Inline
body \displaystyle\sum_{i=1}^{k} s_i=n
,
LaTeX Math Inline
body \displaystyle\sum_{i=1}^{k} D_i=M
,
LaTeX Math Inline
body D_i \geq s_i \geq 0
,
LaTeX Math Inline
body M>D_i>0 | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 1, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.9986698627471924, "perplexity": 533.2943233432237}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2022-33/segments/1659882571198.57/warc/CC-MAIN-20220810161541-20220810191541-00451.warc.gz"} |
http://www.ams.org/cgi-bin/bookstore/booksearch?fn=100&pg1=CN&s1=Shimada_Hideo&arg9=Hideo_Shimada | New Titles | FAQ | Keep Informed | Review Cart | Contact Us Quick Search (Advanced Search ) Browse by Subject General Interest Logic & Foundations Number Theory Algebra & Algebraic Geometry Discrete Math & Combinatorics Analysis Differential Equations Geometry & Topology Probability & Statistics Applications Mathematical Physics Math Education
Advanced Studies in Pure Mathematics 2007; 433 pp; hardcover Volume: 48 ISBN-10: 4-931469-42-6 ISBN-13: 978-4-931469-42-6 List Price: US$71 Member Price: US$56.80 Order Code: ASPM/48 This volume contains surveys and original articles based on the talks given at the 40th Finsler Symposium on Finsler Geometry, held on September 9-10, 2005 at Hokkaido Tokai University, Sapporo, Japan. The symposium was not only a meeting of the Finsler geometers from Japan and abroad but also a commemoration of the late Professor Makoto Matsumoto. The papers included in this volume contain fundamental topics of modern Riemann-Finsler geometry, interesting for specialists in Finsler geometry as well as researchers in Riemannian geometry or other fields of differential geometry and its applications. Volumes in this series are freely available electronically 5 years post-publication. Published for the Mathematical Society of Japan by Kinokuniya, Tokyo, and distributed worldwide, except in Japan, by the AMS. Readership Graduate students and research mathematicians interested in analysis and geometry. Table of Contents Part I. Professor Makoto Matsumoto Photos of Makoto Matsumoto H. Shimada and S. V. Sabau -- Matsumoto's legacy. The life and work of Professor Makoto Matsumoto Part II. Hunting Unicorns and Other Topics of Global Finsler Geometry D. Bao -- On two curvature-driven problems in Riemann-Finsler geometry S. Bácsó, X. Cheng, and Z. Shen -- Curvature properties of $$(\alpha, \beta)$$-metrics I. R. Peter -- A connectedness principle in positively curved Finsler manifolds S. V. Sabau and H. Shimada -- Riemann-Finsler surfaces L. Tamássy -- Finsler geometry in the tangent bundle Part III. Finslerian Inspired Differential Geometry P. L. Antonelli and S. F. Rutz -- Perturbations of constant connection Wagner spaces M. Crampin and D. J. Saunders -- Path geometries and almost Grassmann structures R. L. Lovas, J. Pék, and J. Szilasi -- Ehresmann connections, metrics and good metric derivatives R. Miron -- Dynamical systems of the Lagrangian and Hamiltonian mechanical systems Part IV. Complex Finsler Geometry T. Aikou -- The Chern-Finsler connection and Finsler-Kähler manifolds P.-M. Wong -- A survey of complex Finsler geometry | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 1, "mathjax_display_tex": 1, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.35732191801071167, "perplexity": 6343.45657066695}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2015-27/segments/1435375095677.90/warc/CC-MAIN-20150627031815-00030-ip-10-179-60-89.ec2.internal.warc.gz"} |
https://www.physicsforums.com/threads/can-anyone-understand-this.386589/ | # Can Anyone Understand this?
1. Mar 14, 2010
### phymatter
Can Anyone Understand this???
See the attachment///
Can Anyone Understand this???
I mean what metod has he followed to solve this equation for x in terms of y , does someone have any method to solve it other than the quadratic formula??????/
#### Attached Files:
• ###### solve for x.JPG
File size:
10.4 KB
Views:
127
2. Mar 14, 2010
### phyzguy
Re: Can Anyone Understand this???
It's called "completing the square", and it's where the quadratic formula comes from. Remember, if I have:
$$x^2+2ax + a^2 = 0$$ , I can write it as
$$(x+a)^2 = 0$$ .
So if I have
$$ax^2+bx+c = 0$$
I can write it as:
$$x^2+\frac{b}{a}x+(\frac{b}{2a})^2 =(\frac{b}{2a})^2-\frac{c}{a}$$
where I have added $$(\frac{b}{2a})^2$$ to both sides. This is also:
$$(x+\frac{b}{2a})^2 = (\frac{b}{2a})^2-\frac{c}{a}$$
or:
$$(x+\frac{b}{2a}) =\pm\sqrt{(\frac{b}{2a})^2-\frac{c}{a}}$$
or:
$$x =-\frac{b}{2a}\pm\sqrt{(\frac{b}{2a})^2-\frac{c}{a}}$$
or:
$$x =\frac{-b\pm\sqrt{b^2-4ac}}{2a}$$
This is what they have done, but with $$\frac{7y+13}{24}$$ playing the role of $$\frac{b}{2a}$$
3. Mar 14, 2010
### phymatter
Re: Can Anyone Understand this???
Thanks friend | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 1, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.9674099087715149, "perplexity": 1742.1574496239107}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2018-39/segments/1537267163146.90/warc/CC-MAIN-20180926022052-20180926042452-00131.warc.gz"} |
https://mitpress.mit.edu/books/introduction-machine-learning-0 | Hardcover | $60.00 Text | £41.95 | ISBN: 9780262028189 | 640 pp. | 8 x 9 in | 192 b&w illus.| August 2014 Ebook |$60.00 Text | ISBN: 9780262325738 | 640 pp. | 8 x 9 in | 192 b&w illus.| August 2014
About MIT Press Ebooks
# Introduction to Machine Learning, third edition
## Overview
The goal of machine learning is to program computers to use example data or past experience to solve a given problem. Many successful applications of machine learning exist already, including systems that analyze past sales data to predict customer behavior, optimize robot behavior so that a task can be completed using minimum resources, and extract knowledge from bioinformatics data. Introduction to Machine Learning is a comprehensive textbook on the subject, covering a broad array of topics not usually included in introductory machine learning texts. Subjects include supervised learning; Bayesian decision theory; parametric, semi-parametric, and nonparametric methods; multivariate analysis; hidden Markov models; reinforcement learning; kernel machines; graphical models; Bayesian estimation; and statistical testing.
Machine learning is rapidly becoming a skill that computer science students must master before graduation. The third edition of Introduction to Machine Learning reflects this shift, with added support for beginners, including selected solutions for exercises and additional example data sets (with code available online). Other substantial changes include discussions of outlier detection; ranking algorithms for perceptrons and support vector machines; matrix decomposition and spectral methods; distance estimation; new kernel algorithms; deep learning in multilayered perceptrons; and the nonparametric approach to Bayesian methods. All learning algorithms are explained so that students can easily move from the equations in the book to a computer program. The book can be used by both advanced undergraduates and graduate students. It will also be of interest to professionals who are concerned with the application of machine learning methods.
## Instructor Resources for This Title:
Solution Manual
Programs
Lecture Slides
File Of Figures In The Book
## About the Author
Ethem Alpaydin is a Professor in the Department of Computer Engineering at Bogaziçi University, Istanbul.
## Endorsements
“Ethem Alpaydin’s Introduction to Machine Learning provides a nice blending of the topical coverage of machine learning (à la Tom Mitchell) with formal probabilistic foundations (à la Christopher Bishop). This newly updated version now introduces some of the most recent and important topics in machine learning (e.g., spectral methods, deep learning, and learning to rank) to students and researchers of this critically important and expanding field.”
John W. Sheppard, Professor of Computer Science, Montana State University
“I have used Introduction to Machine Learning for several years in my graduate Machine Learning course. The book provides an ideal balance of theory and practice, and with this third edition, extends coverage to many new state-of-the-art algorithms. I look forward to using this edition in my next Machine Learning course.”
Larry Holder, Professor of Electrical Engineering and Computer Science, Washington State University
“This volume is both a complete and accessible introduction to the machine learning world. This is a ‘Swiss Army knife’ book for this rapidly evolving subject. Although intended as an introduction, it will be useful not only for students but for any professional looking for a comprehensive book in this field. Newcomers will find clearly explained concepts and experts will find a source for new references and ideas.”
Hilario Gómez-Moreno, IEEE Senior Member, University of Alcalá, Spain | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 1, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.21938376128673553, "perplexity": 1802.6947248592269}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.3, "absolute_threshold": 10, "end_threshold": 5, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2015-32/segments/1438042989018.48/warc/CC-MAIN-20150728002309-00007-ip-10-236-191-2.ec2.internal.warc.gz"} |
http://math.stackexchange.com/questions/69194/do-ambivalent-axioms-have-a-place-in-mathematics | # Do Ambivalent Axioms have a place in Mathematics?
I can't think of any examples of ambivalent axioms in mathematics (two ideas are ambivalent if there are sometimes conflicts between them), so please let me humor you with a strange example. Suppose someone was working on a mathematical theory of economies and wanted to account for everyone's perspective and also minimize harm. So in addition to these two axioms, "harm" and "perspective" and "valid" would have to be defined:
1) Do no harm 2) All perspectives are valid
So, in the theory, suppose you come to a point where you want to apply axiom 2 but it conflicts with axiom 1, for instance, a portion of the people have a perspective such that if their will were carried out without being moderated by the other peoples' perspective, there would be harm caused to people, some other life on the planet, or the ecosystem. Then what do you do to resolve this conflict? One solution is to "split" the theory into two branches, one in which you ignore 1, and the other in which you ignore the perspectives of that harm-causing group. There are other ways to do this too, but this is just a stupid example anyway.
So with that scenario in mind, when there are ambivalent axioms, the theory branches into a tree of results in a way that is unlike conventional mathematics.
So my questions are, have I made a brain fart? If not, could ambivalent-axiom theories be transformed into conventional non-ambivalent axiom theories after all definitions given? Would this help mathematics at all or is this solely the territory of other sciences like psychology and psychohistory? Is this abuse of the beautiful, well-tested mechanisms of mathematics, and if there were some conflicting idea in a theory it would enter the stage in another way like an "if statement."
My apologies for not thinking this through myself. I'm not in a mathy perspective lately and am lazy :D
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In a logical system that obeys classical logic, if two axioms are "sometimes in conflict", i.e., if you can deduce contradictory answers from them, then you can prove anything; as such, any theory with "ambivalent axioms" would be inconsistent and hence uninteresting. There is plenty of work in studying how a "core" theory behaves under the addition of different axioms; e.g., ZF+Determinacy vs. ZF+Choice, so I don't see why you say that such a thing would be "unlike conventional mathematics" (unless you think Set Theory and Model Theory are not conventional mathematics). – Arturo Magidin Oct 2 '11 at 5:58
Can someone please re-tag this? I'm really not sure how, but at least one tag seems completely off. – Asaf Karagila Oct 2 '11 at 6:03
Psychohistory? As in, the field founded by Hari Seldon in the latter days of the First Galactic Empire?? – Pete L. Clark Oct 2 '11 at 14:03
Mathematics which works with concrete ideas has some problem with conflicting axioms. Mostly because there is no such thing as a little bit of contradiction. You can only derive contradiction; and from it you can derive anything - which means theories in which there is a contradiction are not useful.
There are examples, however, to incompatible axioms (which is a better, and more common name than ambivalent). In set theory, there can be axioms which do not fit together as additional axioms of Zermelo-Fraenkel set theory.
Examples are:
1. $V=L$, Goedel's Axiom of Constructibility,
2. $AD$, The Axiom of Determinacy, which says that every game over the reals is determined.
3. $AC+\exists \kappa$ measurable, that is the combination of both the Axiom of Choice and the existence of a measurable cardinal.
Each pair of the three above is incompatible. However each one fits just fine with the rest of the ZF axioms.
(Although to be fair we do not know if ZF itself is consistent, and thus we cannot conclude the consistency of any of the combinations above; however assertions as the existence of a measurable cardinal are strong additions to the theory, and they can provide enough power to prove the consistency of ZF. Which means they cannot prove their own consistency, or else we would have a contradiction.)
There are many similar examples of how some axioms can be incompatible. However in many places mathematicians are interested in the implications, which gives them the freedom to assume the axioms they prefer.
Lastly, there is still the idea of Boolean-valued logic. In this logic we assign truth values which are not just $0,1$ (or True, False) but rather enrich the truth with further values. In this case a theorem may have truth value $a$, and another may have truth value $b$, while $a\land b=0$.
That is to say that we can prove two theorems which are both not false (which is different than being true, in this context) but the assumption of both is indeed false.
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There have been some attempts, collectively known as paraconsistent logics, to construct logical systems that can deal with contradiction more gradually than exploding all at once. They are not intended to be used used as a basis for general mathematics, however -- but are available as one tool among many in mathematical modeling. – Henning Makholm Oct 2 '11 at 7:10
@Henning: Thanks, I was not aware of this. – Asaf Karagila Oct 2 '11 at 13:07 | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 1, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.8744971752166748, "perplexity": 445.347746431101}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2014-52/segments/1418802769550.123/warc/CC-MAIN-20141217075249-00103-ip-10-231-17-201.ec2.internal.warc.gz"} |
https://www.physicsforums.com/threads/alternative-real-gas-equation-of-state.528391/ | Alternative Real Gas Equation of State
1. Sep 8, 2011
critter
1. A friend suggests to you an alternative to the Virial equation of state: P=(RT/Vm)-(B/Vm2)+(C/Vm3)
a.) Show that this equation is useful by proving that it demonstrates critical behavior.
b.) Find the critical constants Pc, Vm,c, and Tcin terms of B, C and R.
c.) Calculate the compressibility factor Zc.
Vm=molar volume, P=pressure, T=temp, and B&C would normally be the first and second virial constants.
2. I know that first and second derivatives of pressure with respect to volume should be zero at the critical temperature.
3. Through an algebraic nightmare, I figured out that Tc is equal to (6Vm^3(B+C)-12C+2BVm^2)/(RVm^2(2+Vm)) by taking the first and second derivatives, then setting them equal to each other since they should both be zero at Tc. I have no idea how to find Pc, Vc or Vm since it doesn't appear possible to isolate Vm. How should I proceed?
Can you offer guidance or do you also need help?
Draft saved Draft deleted
Similar Discussions: Alternative Real Gas Equation of State | {"extraction_info": {"found_math": false, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.8906853199005127, "perplexity": 1195.7697574506244}, "config": {"markdown_headings": false, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.3, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2017-47/segments/1510934807056.67/warc/CC-MAIN-20171124012912-20171124032912-00506.warc.gz"} |
http://science.sciencemag.org/content/274/5285/165.1 | Letters
# Where It's At
+ See all authors and affiliations
Science 11 Oct 1996:
Vol. 274, Issue 5285, pp. 165
DOI: 10.1126/science.274.5285.165a
This is a PDF-only article. The first page of the PDF of this article appears below. | {"extraction_info": {"found_math": false, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.8027700781822205, "perplexity": 5288.511055391586}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.3, "absolute_threshold": 20, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2017-26/segments/1498128320582.2/warc/CC-MAIN-20170625203122-20170625223122-00611.warc.gz"} |
http://math.stackexchange.com/questions/359047/double-fourier-series-cosnx-cosmy | # Double Fourier Series $\cos(nx)\cos(my)$
Let $f(x,y) = xy$ on the square $[0, \pi]^2$. Find the Fourier cosine-cosine series of $f$.
I am working on this question with a group and one of us gets all the coefficients as zero. Is this correct or not?
Also, we are at a disagreement about whether to integrate over $[-\pi,\pi]$ or $[-\pi /2,\pi /2]$.
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then?.......... – Xiaolang Apr 12 '13 at 2:40
Sorry I forgot a part of it – Username Unknown Apr 12 '13 at 2:41
Your title doesn't match your definition of $f$. – Stefan Smith Apr 12 '13 at 3:40
Could you briefly recall how the Fourier cosine-cosine series is defined? – 1015 Apr 12 '13 at 3:46
I am unsure what you are asking because it is a long summation that consist of sines and cosines and sine-cosine and cosine-sine and cosine-cosine and sine-sine. – Username Unknown Apr 12 '13 at 3:50 | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 1, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.9142097234725952, "perplexity": 1055.0385909010756}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2015-18/segments/1429246652114.13/warc/CC-MAIN-20150417045732-00128-ip-10-235-10-82.ec2.internal.warc.gz"} |
http://www.sciforums.com/threads/a-crazy-idea-about-inertial-motion.142745/ | # A crazy idea about inertial motion
Discussion in 'Alternative Theories' started by Le Repteux, Oct 9, 2014.
1. ### Le RepteuxRegistered Senior Member
Messages:
105
Hi everybody!
Yes, another crazy idea from an outsider, but sharpen your teeth those who use to eat crank meat for dinner, I'm going to give you a tough ride.
Here is the general idea: since, at the atomic scale, energy is always quantized, I suggest that motion could be.
I begin with a mind experiment:
- Imagine two cars at rest on the same straight road but one km away from one another and heading in the same direction.
- There is an emitter and a receiver in each car and the signal exchanged between them is about the speed from their speedometer.
- One of the cars accelerates and decelerates for 10 seconds, so a signal is emitted every fraction of second indicating the speed at which the car is going.
- Lets us admit that the signal will take more time to travel one km than the time it takes for the car to accelerate and decelerate to rest.
- When the signal will arrive at the second car, at each fraction of second, its receiver will indicate exactly the speed at which it has to accelerate and decelerate.
- While it does as precisely as it can, its own emitter will transmit the signal to the other car, which will repeat exactly the same move forward, and so on for the next car, indefinitely. If the energy to move the cars could be infinite, the signal absolutely precise, and the steps absolutely precise, this slinky kind of motion would never end.
Now, replace the cars by two identical atoms linked together to form a molecule, and imagine that the energy they exchange to maintain their link is quantized, which means that it would have the form of a signal, which would have to be constant for their link to be constant. These two atoms, represented by their nuclei, are very far apart, like the two cars, far enough for the signal to take more time to travel that distance than for an atom to make a step towards the other atom. Lets assume now that one of them is forced to make such a step because it undergoes a push, and that the signal does not have time to reach the other atom before the step is finished.
If the energy of their link has to stay the same, won't the two atoms be forced to proceed exactly like the two cars? Observed from far away, wouldn't the motion of that molecule look like an inertial motion?
3. ### Le RepteuxRegistered Senior Member
Messages:
105
Ah, I forgot something!
Could those who do not like this idea at first sight wait for those who like it to give their opinion first? Thus wait a couple of days before posting? Why? If you don't see why, wait a couple of days before posting please.
Last edited: Oct 9, 2014
5. ### rpennerFully WiredStaff Member
Messages:
4,833
In the OP, you didn't propose anything like a physics hypothesis. What do slow moving signals have to do with the hypothetical quantization of motion. What are the units of quantization of motion?
That is the antithesis of scientific methodology. People who have objections go to the front of the line, not the back.
7. ### Le RepteuxRegistered Senior Member
Messages:
105
Hi rpenner,
Wait two days, and if nobody likes the idea, you will be in the front. But if you want me to answer you now, you can also tell me you like it.
8. ### DywyddyrPenguinaciously duckalicious.Valued Senior Member
Messages:
18,645
Nobody liked it when you posted this drivel on a different science forum.
What makes you think it'll get a better reception here?
9. ### Le RepteuxRegistered Senior Member
Messages:
105
I think that my former posts about my fingers have been erased, which means that a moderator thought that I could find a better answer to the last two posts. I can, but when I read about me words like "drivel and troll", I feel an urge to defend myself, and what a better way to do so than to attack with the same kind of words. DY, I am here because I think that it takes chance for an idea like mine to be understood, not to be accepted, but only understood, and what a better way to increase chance than to increase possibilities. Dr, I think that your post should have been deleted just like mine, because you're doing the same thing that you reproach others to do, and because that behavior is listed in the rules of the forum.
10. ### rpennerFully WiredStaff Member
Messages:
4,833
I'm still waiting for someone who likes your post to explain how it has a connection with physics or quantization of momentum or is even any type of thought experiment.
Reference
You are the one who labeled this idea as "crazy" and suggested it should be pounced upon by those who oppose the postings of "cranks." In these two points, we collectively agree with you, but think you are being dishonest by claiming you came here to "discuss" anything.
11. ### Le RepteuxRegistered Senior Member
Messages:
105
Thinking that I am dishonest means that you don't like the idea as it is. The words that we use carry their emotional meaning event if we don't want them to, but if we do want them to, they can produce an enormous bad emotion to others, and a very good emotion to us. As part of a scientific community, people should be able to pay attention to that kind of talk, but as we can see, lots of them don't. Kids do the same at school, but they are only kids. If there is any psychologist here, he should be able to recognize that social problem: is there?
You say that physics is not about speculation, so I suspect that you do not like to speculate. Some scientists do, some don't, but almost everybody buys lottery tickets. Do you?
Messages:
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Sure physics is about speculation....and Imagination as well. The trick for any individual though, is to be open enough, and man enough, to accept when that same speculation, and Imagination is not applicable to science and is crap.
But with science forums such as this, anyone, any Tom, Dick, and Harry, are able to come along, treat Einstein and other greats with contempt, and then when informed that their ideas, speculations are crap, boringly claim that the scientific method and peer review, does not work and is tainted.
Maladies that drive such conditions are "Delusions of grandeur" "Tall poppy syndrome" and an anti establishment bias.
These same people, with the same maladies, then tend to wear them like a "badge of honour"
13. ### Le RepteuxRegistered Senior Member
Messages:
105
From your post, I understand that a lot of scientists here are fed up with crazy ideas that have nothing to do with science, and I also understand why since I can recognize those myself, so I don't mind if they ask questions and if they seem skeptic about my ideas. What I cannot stand is the name calling. When people are respectful, we must respect them even if we know we are right. After all, there is no need to degrade someone to show that his ideas are not scientific, and I think that people that observe the discussions are intelligent enough to understand that.
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21,647
Sometimes the name calling starts from the other side, and of course sometimes the down right arrogance of some alternative pushers is staggering beyond belief, and the real scientists, being human, may crack under such quackery put as fact.
15. ### zgmcRegistered Senior Member
Messages:
760
I don't see how your idea is relevant to anything in our current reality. Do you have a real world example that could further define the point that you are trying to make in the OP?
16. ### river
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9,793
Actually no it isn't , the " antithesis " of science methodology
I'm sure that when a paper is presented it takes time to truly understand the idea
17. ### rpennerFully WiredStaff Member
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I'm not saying I don't understand it. I'm saying I don't see that a physics hypothesis was presented.
Comparing the OP to a scientific paper would be futile because the poster has no interest in the methodology of science.
18. ### river
Messages:
9,793
in what way ?
19. ### Le RepteuxRegistered Senior Member
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105
Hi River, thanks for understanding the problem.
RP, I said that you were going to be the first, so here you are. Before talking about units, do you agree that, as a group, the two cars will follow each other in the same direction and at the same speed indefinitely?
The thought experiment is about inertial motion, so it might not have come to your mind that it is also about mass, because mass is related to resistance to acceleration, and because inertial motion is only considered as an artifact from mass. I will come to that point later, but for now, I want to know if you agree with the phenomenon I described.
20. ### danshawenValued Senior Member
Messages:
3,942
I don't see what there is not to like about this idea. Could not a constant velocity be achieved by means of infinitesimal accelerations / decelerations? Momentum (both direction and magnitude) is on average conserved, so what's the beef? Of course it works.
So long as the component of the acceleration in the general direction of the original push is maintained, it works by any calculus I know. The idea is a perfect demonstration of why a perfectly rigid solid substance, even bound in something like a crystal or metal lattice, cannot exist for something constructed of atoms. For reasons I never understood, some people seem to have trouble understanding this model of a solid. They will negate the speed of light as a universal speed limit and start talking about a pair of scissors several light years long, or else a rotating beacon as examples of things that can break that limit. They can't, and this is part of the reason why.
A former colleague of mine has an expression for maximal acceleration, classically derived, if anyone is interested. It might help build this model.
Inertia can also be imparted to bound energy, like photons bouncing between a pair of mirrors. This gets a bit tricky in the details however. In every example Wheeler ever gave of this thought experiment, for example, he entirely missed the point that each time the photon bounces, it is absorbed by a free electron in the mirror sharing the inertia of the box, train, spaceship, or whatever, and then is re-emitted in a manner that gives the photon a slight push in the direction of the moving inertial frame. If the photon were released from the box and reflected from some nearby mirror planet outside of the moving spacecraft, the photon would no longer share the inertia of the original box because it was reflected by a bound electron with some other inertial state. Otherwise, the size of the mirror box shouldn't make any difference, should it?
I like it when people think more carefully about what it means to have inertia. I have an idea it's going to be very important quite soon, thanks in part to the discovery of the boson responsible for the Higgs mechanism and atomic inertia.
21. ### Le RepteuxRegistered Senior Member
Messages:
105
Hi Dan, thanks for the like!
Could you construct that phrase differently so that I can understand exactly what you mean please?
I think that you did not realize that the kind of steps I am talking about for the atoms mean that their mass does not come from the Higgs. With their steps, two linked atoms would resist a change in their link energy, so that if a first one is pushed towards the other one, that first one will tend to get back to where it was during the time it takes for this information to get to the other atom. It would thus be the time gap from any interaction that would produce mass, and it would also produce inertial motion for the same reason, whereas the Higgs does not explain the latter. Two explanations for the price of one, who wants to buy? Say "I like" and its yours!
Last edited: Oct 11, 2014
22. ### rpennerFully WiredStaff Member
Messages:
4,833
No. That does not follow, since the signal between cars is delayed. Further, because of geometrical effects, it does not immediately follow that the cars have simple impulse responses.
$y'(t) = \int_{-\infty}^{t} z'(u) \left( ( c - z'(u)) \delta(y(t)-z(u) + c(u-t)) + ( c + z'(u)) \delta(y(t)-z(u) - c(u-t)) \right) du \\ z'(t) = \int_{-\infty}^{t} y'(u) \left( ( c - y'(u)) \delta(z(t)-y(u) + c(u-t)) + ( c + y'(u)) \delta(z(t)-y(u) - c(u-t)) \right) du$
where y is the position of the first car, z is the position of the second and c is the propagation speed of the signal and $\delta()$ is the Dirac delta function.
Assuming y(t) > x(t) we get:
$y'(t) = \int_{-\infty}^{t} z'(u) ( c - z'(u)) \delta(y(t) + c t -z(u) + c u) du \\ z'(t) = \int_{-\infty}^{t} y'(u) ( c + y'(u)) \delta(z(t) - c t -y(u) - cu) du$
Certainly $y(t) = 1 + v t, z(t) = v t, y'(t) = v, z'(t) = v$ is a solution for $-c \lt v \lt c$, but one that does not match your initial conditions.
23. ### Le RepteuxRegistered Senior Member
Messages:
105
Thanks for the nice maths RP, but before commenting them, what kind of geometrical effects are you talking about, and how would it affect the impulses? | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 1, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.6986804008483887, "perplexity": 708.638200845836}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2017-51/segments/1512948592846.98/warc/CC-MAIN-20171217015850-20171217041850-00474.warc.gz"} |
http://jamescurran.co.nz/2018/05/some-quirks-of-jags/ | Some quirks of JAGS
I return to JAGS infrequently enough these days that I forget a lot of things. Do not get me wrong. I love JAGS and I think it is one of the most valuable tools in my toolbox. However administrative and professional duties often destroy any chance I might have of concentrating long enough to actually do some decent statistics.
Despite this I have been working with my colleagues and friends, Duncan Taylor and Mikkel Andersen–who has been visiting from Aalborg since February and really boosting my research, on some decent Bayesian modelling. Along the way we have encountered a few idiosyncrasies of JAGS which are probably worth documenting. I should point out that the issues here have been covered by Martyn Plummer and others on Stack Overflow and other forums, but perhaps not as directly.
Local variables
JAGS allows local variables. In fact you probably use them without realizing as loop indices. However, what it does not like is the declaration of local variables within a loop. That is
model{
k <- 10
}
is fine, whereas
model{
for(i in 1:10){
k <- 10
}
}
is not. This would be fine, except the second code snippet will yield an error which tells you that k is an unknown variable and asks you to: Either supply values for this variable with the data or define it on the left hand side of a relation. I think this error message is a bit of a head scratcher because look at your code and say “But I have defined it, and it works in R.” – do not fall into the latter mode of thinking – it’s a trap!
There are a couple of solutions to this problem. Firstly, you could do as I did and give up on having your model code readable, and just not use temporary variables like this, or, secondly, you could like the temporary variable vary with the index, like so
model{
for(i in 1:10){
k[i] <- 10
}
}
Missing data / ragged arrays
JAGS cannot deal with missing covariates very well. However, it is happy enough for you to include these observations and “step over” them some how. An example of this might be a balanced experiment where some of the trials failed. As an example let us consider a simple two factorial completely randomised design where each factor only has two levels. Let the first factor have levels A and B, and the second factor have levels 1 and 2. Furthermore let there be 3 replicates for each treatment (combination of the factors). Our (frequentist) statistical model for this design would be
$$y_{ijk}=\mu + \alpha_i + \beta_j + \gamma_{ij} + \varepsilon_{ijk},~i\in\{A,B\},j\in\{1,2\},k=1,\ldots,3,\varepsilon_{ijk}\sim N(0,\sigma^2)$$
And we would typically programme this up in JAGS as something like this
model{
for(i in 1:2){
for(j in 1:2){
for(k in 1:3){
y[i,j,k] ~ dnorm(mu[i,j], tau)
}
mu[i,j] <- alpha[i] + beta[j] + gamma[i,j]
}
}
for(i in 1:2){
alpha[i] ~ dnorm(0, 0.000001)
}
for(j in 1:2){
beta[j] ~ dnorm(0, 0.000001)
}
for(i in 1:2){
for(j in 1:2){
gammma[i,j] ~ dnorm(0, 0.000001)
}
}
tau ~ dgamma(0.001, 0.001)
}
Implicit in this code is that y is a 2 x 2 x 3 array, and that we have a fully balanced design. Now let us assume that, for some reason, the treatments $$\tau\in\{A1,A2,B1,B2\}$$ have been replicated 2, 3, 2, 3 times respectively. We can deal with this in JAGS by creating another variable in our input data which we will call reps with reps = c(3, 2, 3, 2). This then can be accommodated in our JAGS model by
model{
for(i in 1:2){
for(j in 1:2){
for(k in 1:reps[(i-1) * 2 + j]){
y[i,j,k] ~ dnorm(mu[i,j], tau)
}
mu[i,j] <- alpha[i] + beta[j] + gamma[i,j]
}
}
y is still a 2 x 2 x 3 array, but simply has NA stored in the positions without information. It is also worth noting that ever since JAGS 4.0 the syntax for loops allows
for(v in V){
where V is a vector containing integer indices. This is very useful for irregular data.
NOTE I have not compiled the JAGS code in my second example, so please let me know if there are mistakes. This is an ongoing article and so I may update it from time to time.
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https://worldwidescience.org/topicpages/u/undergraduate+thermo-fluids+laboratory.html | #### Sample records for undergraduate thermo-fluids laboratory
1. Thermo-fluid behaviour of periodic cellular metals
CERN Document Server
Lu, Tian Jian; Wen, Ting
2013-01-01
Thermo-Fluid Behaviour of Periodic Cellular Metals introduces the study of coupled thermo-fluid behaviour of cellular metals with periodic structure in response to thermal loads, which is an interdisciplinary research area that requires a concurrent-engineering approach. The book, for the first time, systematically adopts experimental, numerical, and analytical approaches, presents the fluid flow and heat transfer in periodic cellular metals under forced convection conditions, aiming to establish structure-property relationships for tailoring material structures to achieve properties and performance levels that are customized for defined multifunctional applications. The book, as a textbook and reference book, is intended for both academic and industrial people, including graduate students, researchers and engineers. Dr. Tian Jian Lu is a professor at the School of Aerospace, Xi’an Jiaotong University, Xi’an, China. Dr. Feng Xu is a professor at the Key Laboratory of Biomedical Information Engineering o...
2. Introduction to thermo-fluids systems design
CERN Document Server
Garcia McDonald, André
2012-01-01
A fully comprehensive guide to thermal systems design covering fluid dynamics, thermodynamics, heat transfer and thermodynamic power cycles Bridging the gap between the fundamental concepts of fluid mechanics, heat transfer and thermodynamics, and the practical design of thermo-fluids components and systems, this textbook focuses on the design of internal fluid flow systems, coiled heat exchangers and performance analysis of power plant systems. The topics are arranged so that each builds upon the previous chapter to convey to the reader that topics are not stand-alone i
3. Thermo-Fluid Dynamics of Two-Phase Flow
CERN Document Server
Ishii, Mamrou
2011-01-01
"Thermo-fluid Dynamics of Two-Phase Flow, Second Edition" is focused on the fundamental physics of two-phase flow. The authors present the detailed theoretical foundation of multi-phase flow thermo-fluid dynamics as they apply to: Nuclear reactor transient and accident analysis; Energy systems; Power generation systems; Chemical reactors and process systems; Space propulsion; Transport processes. This edition features updates on two-phase flow formulation and constitutive equations and CFD simulation codes such as FLUENT and CFX, new coverage of the lift force model, which is of part
4. Undergraduate Laboratory for Surface Science
Science.gov (United States)
Okumura, Mitchio; Beauchamp, Jesse L.; Dickert, Jeffrey M.; Essy, Blair R.; Claypool, Christopher L.
1996-02-01
Surface science has developed into a multidisciplinary field of research with applications ranging from heterogeneous catalysis to semiconductor etching (1). Aspects of surface chemistry are now included in physical chemistry textbooks (2) and undergraduate curricula (3), but the perceived cost and complexity of equipment has deterred the introduction of surface science methods in undergraduate laboratories (4). Efforts to expose chemistry undergraduates to state-of-the-art surface instrumentation have just begun (5). To provide our undergraduates with hands-on experience in using standard techniques for characterizing surface morphology, adsorbates, kinetics, and reaction mechanisms, we have developed a set of surface science experiments for our physical chemistry laboratory sequence. The centerpiece of the laboratory is an ultrahigh vacuum (UHV) chamber for studies of single crystal surfaces. This instrument, shown in the figure, has surface analysis capabilities including low energy electron diffraction (LEED), Auger spectroscopy, and temperature-programmed desorption (TPD). The laboratory exercises involve experiments on the well-studied Pt(111) surface. Students prepare a previously mounted single crystal sample by sputtering it with an argon ion gun and heating it under O2. Electron diffraction patterns from the cleaned surface are then obtained with a reverse view LEED apparatus (Princeton Instruments). Images are captured by a charge-coupled device (CCD) camera interfaced to a personal computer for easy downloading and subsequent analysis. Although the LEED images from a Pt(111) surface can be readily interpreted using simple diffraction arguments, this lab provides an excellent context for introducing Miller indices and reciprocal lattices (6). The surface chemical composition can be investigated by Auger spectroscopy, using the LEED apparatus as a simple energy analyzer. The temperature programmed desorption experiment, which is nearly complete, will be
5. Argumentation in undergraduate chemistry laboratories
Science.gov (United States)
Walker, Joi Phelps
To address the need for reform in undergraduate science education a new instructional model called Argument-Driven Inquiry (ADI) was developed and then implemented in a undergraduate chemistry course at a community college in the southeastern United States (Sampson, Walker, & Grooms, 2009; Walker, Sampson, & Zimmerman, in press). The ADI instructional model is designed to give a more central place to argumentation and the role of argument in the social construction of scientific knowledge. This research investigated the growth in the quality of the student generated arguments and the scientific argumentation that took place over the course of a semester. Students enrolled in two sections of General Chemistry I laboratory at the community college participated in this study. The students worked in collaborative groups of three or four. The students were given a variation of the same performance task three times during the semester in order to measure individual ability to use evidence and justify their choice of evidence with appropriate rationale. Five ADI investigations took place during the semester and the laboratory reports for each were collected from each student and the argument section of each report was scored. All the student groups were video recorded five times during the semester as they generated and evaluated arguments and the quality of the group argumentation was assessed using an instrument called the Assessment of Scientific Argumentation in the Classroom (ASAC) observation protocol. As time was the independent variable in this study a repeated measure ANOVA was used to evaluate the significance of student improvement in each area (argumentation, written argument and performance task) over the course of the semester (Trochim, 1999). In addition, a multiple regression analysis was conducted to evaluate how well the ASAC scores predicted individual scores on both the performance task and the written arguments (Green & Salkind, 2005). There was
6. Fluid Flow Experiment for Undergraduate Laboratory.
Science.gov (United States)
Vilimpochapornkul, Viroj; Obot, Nsima T.
1986-01-01
The undergraduate fluid mechanics laboratory at Clarkson University consists of three experiments: mixing; drag measurements; and fluid flow and pressure drop measurements. The latter experiment is described, considering equipment needed, procedures used, and typical results obtained. (JN)
7. Fast reactor safety and computational thermo-fluid dynamics approaches
International Nuclear Information System (INIS)
Ninokata, Hisashi; Shimizu, Takeshi
1993-01-01
This article provides a brief description of the safety principle on which liquid metal cooled fast breeder reactors (LMFBRs) is based and the roles of computations in the safety practices. A number of thermohydraulics models have been developed to date that successfully describe several of the important types of fluids and materials motion encountered in the analysis of postulated accidents in LMFBRs. Most of these models use a mixture of implicit and explicit numerical solution techniques in solving a set of conservation equations formulated in Eulerian coordinates, with special techniques included to specific situations. Typical computational thermo-fluid dynamics approaches are discussed in particular areas of analyses of the physical phenomena relevant to the fuel subassembly thermohydraulics design and that involve describing the motion of molten materials in the core over a large scale. (orig.)
8. Undergraduate Organic Chemistry Laboratory Safety
Science.gov (United States)
Luckenbaugh, Raymond W.
1996-11-01
Each organic chemistry student should become familiar with the educational and governmental laboratory safety requirements. One method for teaching laboratory safety is to assign each student to locate safety resources for a specific class laboratory experiment. The student should obtain toxicity and hazardous information for all chemicals used or produced during the assigned experiment. For example, what is the LD50 or LC50 for each chemical? Are there any specific hazards for these chemicals, carcinogen, mutagen, teratogen, neurotixin, chronic toxin, corrosive, flammable, or explosive agent? The school's "Chemical Hygiene Plan", "Prudent Practices for Handling Hazardous Chemicals in the Laboratory" (National Academy Press), and "Laboratory Standards, Part 1910 - Occupational Safety and Health Standards" (Fed. Register 1/31/90, 55, 3227-3335) should be reviewed for laboratory safety requirements for the assigned experiment. For example, what are the procedures for safe handling of vacuum systems, if a vacuum distillation is used in the assigned experiment? The literature survey must be submitted to the laboratory instructor one week prior to the laboratory session for review and approval. The student should then give a short presentation to the class on the chemicals' toxicity and hazards and describe the safety precautions that must be followed. This procedure gives the student first-hand knowledge on how to find and evaluate information to meet laboartory safety requirements.
9. Guaiacol Peroxidase Zymography for the Undergraduate Laboratory
Science.gov (United States)
Wilkesman, Jeff; Castro, Diana; Contreras, Lellys M.; Kurz, Liliana
2014-01-01
This laboratory exercise presents a novel way to introduce undergraduate students to the specific detection of enzymatic activity by electrophoresis. First, students prepare a crude peroxidase extract and then analyze the homogenate via electrophoresis. Zymography, that is, a SDS-PAGE method to detect enzyme activity, is used to specifically…
10. Standardization of Thermo-Fluid Modeling in Modelica.Fluid
Energy Technology Data Exchange (ETDEWEB)
Franke, Rudiger; Casella, Francesco; Sielemann, Michael; Proelss, Katrin; Otter, Martin; Wetter, Michael
2009-09-01
This article discusses the Modelica.Fluid library that has been included in the Modelica Standard Library 3.1. Modelica.Fluid provides interfaces and basic components for the device-oriented modeling of onedimensional thermo-fluid flow in networks containing vessels, pipes, fluid machines, valves and fittings. A unique feature of Modelica.Fluid is that the component equations and the media models as well as pressure loss and heat transfer correlations are decoupled from each other. All components are implemented such that they can be used for media from the Modelica.Media library. This means that an incompressible or compressible medium, a single or a multiple substance medium with one or more phases might be used with one and the same model as long as the modeling assumptions made hold. Furthermore, trace substances are supported. Modeling assumptions can be configured globally in an outer System object. This covers in particular the initialization, uni- or bi-directional flow, and dynamic or steady-state formulation of mass, energy, and momentum balance. All assumptions can be locally refined for every component. While Modelica.Fluid contains a reasonable set of component models, the goal of the library is not to provide a comprehensive set of models, but rather to provide interfaces and best practices for the treatment of issues such as connector design and implementation of energy, mass and momentum balances. Applications from various domains are presented.
11. Undergraduate students' goals for chemistry laboratory coursework
Science.gov (United States)
DeKorver, Brittland K.
Chemistry laboratory coursework has the potential to offer many benefits to students, yet few of these learning goals are realized in practice. Therefore, this study seeks to characterize undergraduate students' learning goals for their chemistry laboratory coursework. Data were collected by recording video of students completing laboratory experiments and conducting interviews with the students about their experiences that were analyzed utilizing the frameworks of Human Constructivism and Self-Regulated Learning. A cross-sectional sampling of students allowed comparisons to be made among students with varying levels of chemistry experience and interest in chemistry. The student goals identified by this study were compared to previously described laboratory learning goals of the faculty who instruct these courses in an effort to identify potential avenues to improve laboratory learning.
12. Positron Annihilation in the Undergraduate Laboratory
Science.gov (United States)
Engbrecht, Jason
2017-04-01
While there are a variety of undergraduate laboratory experiments in the literature, they tend to focus on specific positron experiments and use specialized equipment that limit their flexibility. Here we present a positron spectroscopy experimental apparatus designed for the undergraduate lab. Rather than specialized pulse processing the apparatus utilizes a PC oscilloscope as its primary data acquisition utility with pulse processing happening in software instead of hardware. This allows the apparatus to explore a variety of physical phenomena with the positron annihilation including material science, 2 and 3 gamma annihilation properties, polarimetry via Compton scattering, QED tests, and local hidden variable theories. The supporting software is flexible and allows students to pursue these experiments through exploration rather than simply supporting data acquisition. St. Olaf College.
13. Undergraduate physics laboratory: Electrophoresis in chromatography paper
Science.gov (United States)
Hyde, Alexander; Batishchev, Oleg
2015-12-01
An experiment studying the physical principles of electrophoresis in liquids was developed for an undergraduate laboratory. We have improved upon the standard agarose gel electrophoresis experimental regime with a straightforward and cost-effective procedure, in which drops of widely available black food coloring were separated by electric field into their dye components on strips of chromatography paper soaked in a baking soda/water solution. Terminal velocities of seven student-safe dyes were measured as a function of the electric potential applied along the strips. The molecular mobility was introduced and calculated by analyzing data for a single dye. Sources of systematic and random errors were investigated.
14. Undergraduate Laboratory Exercises Specific to Food Spoilage Microbiology
Science.gov (United States)
Snyder, Abigail B.; Worobo, Randy W.; Orta-Ramirez, Alicia
2016-01-01
Food spoilage has an enormous economic impact, and microbial food spoilage plays a significant role in food waste and loss; subsequently, an equally significant portion of undergraduate food microbiology instruction should be dedicated to spoilage microbiology. Here, we describe a set of undergraduate microbiology laboratory exercises that focus…
15. Measuring Dynamic Kidney Function in an Undergraduate Physiology Laboratory
Science.gov (United States)
Medler, Scott; Harrington, Frederick
2013-01-01
Most undergraduate physiology laboratories are very limited in how they treat renal physiology. It is common to find teaching laboratories equipped with the capability for high-resolution digital recordings of physiological functions (muscle twitches, ECG, action potentials, respiratory responses, etc.), but most urinary laboratories still rely on…
16. Introducing Undergraduates to a Research Laboratory
Science.gov (United States)
Weinberg, Robert
1974-01-01
Discusses a student project which is intended to teach undergraduates concepts and techniques of nuclear physics, experimental methods used in particle detection, and provide experience in a functioning research environment. Included are detailed procedures for carrying out the project. (CC)
17. Kinetics of Carbaryl Hydrolysis: An Undergraduate Environmental Chemistry Laboratory
Science.gov (United States)
Hawker, Darryl
2015-01-01
Kinetics is an important part of undergraduate environmental chemistry curricula and relevant laboratory exercises are helpful in assisting students to grasp concepts. Such exercises are also useful in general chemistry courses because students can see relevance to real-world issues. The laboratory exercise described here involves determination of…
Science.gov (United States)
Lewis, Russell L.; Seal, Erin L.; Lorts, Aimee R.; Stewart, Amanda L.
2017-01-01
The undergraduate biochemistry laboratory curriculum is designed to provide students with experience in protein isolation and purification protocols as well as various data analysis techniques, which enhance the biochemistry lecture course and give students a broad range of tools upon which to build in graduate level laboratories or once they…
19. An Undergraduate Nanotechnology Engineering Laboratory Course on Atomic Force Microscopy
Science.gov (United States)
Russo, D.; Fagan, R. D.; Hesjedal, T.
2011-01-01
The University of Waterloo, Waterloo, ON, Canada, is home to North America's first undergraduate program in nanotechnology. As part of the Nanotechnology Engineering degree program, a scanning probe microscopy (SPM)-based laboratory has been developed for students in their fourth year. The one-term laboratory course "Nanoprobing and…
20. EDITORIAL: Student undergraduate laboratory and project work
Science.gov (United States)
Schumacher, Dieter
2007-05-01
that new experiments which illustrate both fundamental physics and modern technology can be realized even with a small budget. Traditional labwork courses often provide a catalogue of well known experiments. The students must first learn the theoretical background. They then assemble the setup from specified equipment, collect the data and perform the default data processing. However, there is no way to learn to swim without water. In order to achieve a constructivist access to learning, 'project labs' are needed. In a project labwork course a small group of students works as a team on a mini research project. The students have to specify the question of research, develop a suitable experimental setup, conduct the experiment and find a suitable way to evaluate the data. Finally they must present their results e.g. in the framework of a public poster session. Three contributions refer to this approach, however they focus on different aspects: 'Project laboratory for first-year students' by Gorazd Planinšič, 'RealTime Physics: active learning laboratories' by David Sokoloff et al and 'Labs outside labs: miniprojects at a spring camp for future physics teachers' by Leos Dvorák. Is it possible to prepare the students specifically for project labwork? This question is answered by the contribution 'A new labwork course for physics students: devices, methods and research projects' by Knut Neumann and Manuela Welzel. The two main parts of the labwork course cover first experimental devices (e.g. multimeters, oscilloscopes, different sensors, operational amplifiers, step motors, AD/DA-converters). Then subjects such as data processing, consideration of measurement uncertainties, keeping records or using tools like LABVIEW etc are focused on. Another concrete proposal for a new curriculum is provided by James Sharp et al, in 'Computer based learning in an undergraduate physics laboratory: interfacing and instrument control using MATLAB'. One can well imagine that project labs
1. Computerized Laboratories in an Undergraduate Psychology Department.
Science.gov (United States)
Brazier, Mary M.
A computer project sponsored by a National Science Foundation grant was completed in the psychology department at Loyola University. The purpose of the project was to upgrade existing laboratory equipment in both the operant learning and sensation/perception laboratories, to provide equipment for a cognition laboratory, and to allow increased and…
2. Measuring meaningful learning in the undergraduate chemistry laboratory
Science.gov (United States)
Galloway, Kelli R.
The undergraduate chemistry laboratory has been an essential component in chemistry education for over a century. The literature includes reports on investigations of singular aspects laboratory learning and attempts to measure the efficacy of reformed laboratory curriculum as well as faculty goals for laboratory learning which found common goals among instructors for students to learn laboratory skills, techniques, experimental design, and to develop critical thinking skills. These findings are important for improving teaching and learning in the undergraduate chemistry laboratory, but research is needed to connect the faculty goals to student perceptions. This study was designed to explore students' ideas about learning in the undergraduate chemistry laboratory. Novak's Theory of Meaningful Learning was used as a guide for the data collection and analysis choices for this research. Novak's theory states that in order for meaningful learning to occur the cognitive, affective, and psychomotor domains must be integrated. The psychomotor domain is inherent in the chemistry laboratory, but the extent to which the cognitive and affective domains are integrated is unknown. For meaningful learning to occur in the laboratory, students must actively integrate both the cognitive domain and the affective domains into the "doing" of their laboratory work. The Meaningful Learning in the Laboratory Instrument (MLLI) was designed to measure students' cognitive and affective expectations and experiences within the context of conducting experiments in the undergraduate chemistry laboratory. Evidence for the validity and reliability of the data generated by the MLLI were collected from multiple quantitative studies: a one semester study at one university, a one semester study at 15 colleges and universities across the United States, and a longitudinal study where the MLLI was administered 6 times during two years of general and organic chemistry laboratory courses. Results from
3. Undergraduate Laboratory Module on Skin Diffusion
Science.gov (United States)
Norman, James J.; Andrews, Samantha N.; Prausnitz, Mark R.
2011-01-01
To introduce students to an application of chemical engineering directly related to human health, we developed an experiment for the unit operations laboratory at Georgia Tech examining diffusion across cadaver skin in the context of transdermal drug delivery. In this laboratory module, students prepare mouse skin samples, set up diffusion cells…
4. Generalized Fluid System Simulation Program (GFSSP) Version 6 - General Purpose Thermo-Fluid Network Analysis Software
Science.gov (United States)
Majumdar, Alok; Leclair, Andre; Moore, Ric; Schallhorn, Paul
2011-01-01
GFSSP stands for Generalized Fluid System Simulation Program. It is a general-purpose computer program to compute pressure, temperature and flow distribution in a flow network. GFSSP calculates pressure, temperature, and concentrations at nodes and calculates flow rates through branches. It was primarily developed to analyze Internal Flow Analysis of a Turbopump Transient Flow Analysis of a Propulsion System. GFSSP development started in 1994 with an objective to provide a generalized and easy to use flow analysis tool for thermo-fluid systems.
5. Picture of Norwegian clinical learning laboratories for undergraduate nursing students.
Science.gov (United States)
Wellard, Sally J; Solvoll, Betty-Ann; Heggen, Kristin M
2009-07-01
Clinical preparation for practice is a vital part of undergraduate education in nursing. This study explored contemporary constructions of clinical skills laboratories in two nursing undergraduate programs in Norway using qualitative collective case study methods. Data were gathered using individual and group interviews and observation during site visits. The data revealed slightly different ways of organizing teaching and experimenting with use of pedagogical methods to facilitate learning of technical skills as well as encouraging students to activate relevant theoretical knowledge. While there was a lively and striking enthusiasm among staff about the way learning was managed within the laboratories, the pedagogical underpinnings for their particular approaches were less certain amongst participants. The paper concludes with the necessity to provide evidence for the outcome of laboratories learning and investigate suitable pedagogical methods for effective teaching and learning of practice skills. Hence, a need for research on transfer of knowledge and skills between the different sites (academy, clinical settings, and laboratories) is identified.
6. Field Research Studying Whales in an Undergraduate Animal Behavior Laboratory
Science.gov (United States)
MacLaren, R. David; Schulte, Dianna; Kennedy, Jen
2012-01-01
This work describes a new field research laboratory in an undergraduate animal behavior course involving the study of whale behavior, ecology and conservation in partnership with a non-profit research organization--the Blue Ocean Society for Marine Conservation (BOS). The project involves two weeks of training and five weekend trips on whale watch…
7. Synthesis and Characterization of Silver Nanoparticles for an Undergraduate Laboratory
Science.gov (United States)
Orbaek, Alvin W.; McHale, Mary M.; Barron, Andrew R.
2015-01-01
The aim of this simple, quick, and safe laboratory exercise is to provide undergraduate students an introduction to nanotechnology using nanoparticle (NP) synthesis. Students are provided two procedures that allow for the synthesis of different yet controlled sizes of silver NPs. After preparing the NPs, the students perform UV-visible…
8. 3D time dependent thermo-fluid dynamic model of ground deformation at Campi Flegrei caldera
Science.gov (United States)
Castaldo, R.; Tizzani, P.; Manconi, A.; Manzo, M.; Pepe, S.; Pepe, A.; Lanari, R.
2012-04-01
In active volcanic areas deformation signals are generally characterized by non-linear spatial and temporal variations [Tizzani P. et al., 2007]. This behaviour has been revealed in the last two decades by the so-called advanced DInSAR processing algorithms, developed to analyze surface deformation phenomena [Berardino P. et al., 2002; Ferretti C. et al., 2001]. Notwithstanding, most of the inverse modelling attempts to characterize the evolution of the volcanic sources are based on the assumption that the Earth's crust behaves as a homogeneous linear elastic material. However, the behaviour of the upper lithosphere in thermally anomalous regions (as active volcanoes are) might be well described as a non-Newtonian fluid, where some of the material proprieties of the rocks (i.e., apparent viscosities) can change over time [Pinkerton H. et al., 1995]. In this context, we considered the thermal proprieties and mechanical heterogeneities of the upper crust in order to develop a new 3D time dependent thermo-fluid dynamic model of Campi Flegrei (CF) caldera, Southern Italy. More specifically, according to Tizzani P. et al. (2010), we integrated in a FEM environment geophysical information (gravimetric, seismic, and borehole data) available for the considered area and performed two FEM optimization procedures to constrain the 3D distribution of unknown physical parameters (temperature and viscosity distributions) that might help explaining the data observed at surface (geothermal wells and DInSAR measurements). First, we searched for the heat production, the volume source distribution and surface emissivity parameters providing the best-fit of the geothermal profiles data measured at six boreholes [Agip ESGE, 1986], by solving the Fourier heat equation over time (about 40 kys). The 3D thermal field resulting from this optimization was used to calculate the 3D brittle-ductile transition. This analysis revealed the presence of a ductile region, located beneath the centre of
9. Basic neuron model electrical equivalent circuit: an undergraduate laboratory exercise.
Science.gov (United States)
Dabrowski, Katie M; Castaño, Diego J; Tartar, Jaime L
2013-01-01
We developed a hands-on laboratory exercise for undergraduate students in which they can build and manipulate a neuron equivalent circuit. This exercise uses electrical circuit components that resemble neuron components and are easy to construct. We describe the methods for creating the equivalent circuit and how to observe different neuron properties through altering the structure of the equivalent circuit. We explain how this hands-on laboratory activity allows for the better understanding of this fundamental neuroscience concept. At the conclusion of this laboratory exercise, undergraduate students will be able to apply the principles of Ohm's law, cable theory with regards to neurons, and understand the functions of resistance and capacitance in a neuron.
10. Measuring Salivary Alpha-Amylase in the Undergraduate Neuroscience Laboratory.
Science.gov (United States)
Bañuelos, Maria S; Musleh, Aya; Olson, Lisa E
2017-01-01
Undergraduate courses in biopsychology, neuroscience, and physiology often include laboratory exercises that examine responses to stimulation of the sympathetic nervous system with measurements of heart rate, blood pressure, or galvanic skin levels (sweat response). A newer bioindicator of the sympathetic nervous system is salivary alpha-amylase (sAA) measured with a colorimetic enzyme assay. Undergraduate students successfully measured a rise in sAA due to the stress of giving a class presentation (n=13). Students were enthusiastic to measure a physiological response to a real-life anxiety-producing situation. We describe potential difficulties in the assay and our adaptations to the manufacturer's protocol to make it more feasible in the undergraduate setting.
11. A thermo fluid dynamic model of wood particle gasification- and combustion processes
Directory of Open Access Journals (Sweden)
G Boiger
2016-09-01
Full Text Available In order to qualitatively understand and evaluate the thermo- fluid dynamic situation within a wood gasification reactor, a 1D particle model has been created. The presented tool accounts for the highly in- stationary, kinetic- and thermo chemical effects, leading to partial gasification and combustion of a wood particle embedded within a packed bed collective. It considers the fluid- dynamic situation within the changing porous bulk structure of the packed bed, its impact on species- and heat transition mechanisms, the energy- and mass balances of wood, coal, pyrolysis-gas, wood- gas and off- gas phases, the thermodynamics of locally developing gasification- and combustion reaction equilibria, as well as the presence of the chemical species hydrogen, water, carbon (di- oxide, methane, oxygen, solid carbon and gaseous, longer chain hydrocarbons from pyrolysis. Model results can be shown to yield very good, qualitative agreement with measurements, found in literature.
12. Blended learning within an undergraduate exercise physiology laboratory.
Science.gov (United States)
Elmer, Steven J; Carter, Kathryn R; Armga, Austin J; Carter, Jason R
2016-03-01
In physiological education, blended course formats (integration of face-to-face and online instruction) can facilitate increased student learning, performance, and satisfaction in classroom settings. There is limited evidence on the effectiveness of using blending course formats in laboratory settings. We evaluated the impact of blended learning on student performance and perceptions in an undergraduate exercise physiology laboratory. Using a randomized, crossover design, four laboratory topics were delivered in either a blended or traditional format. For blended laboratories, content was offloaded to self-paced video demonstrations (∼15 min). Laboratory section 1 (n = 16) completed blended laboratories for 1) neuromuscular power and 2) blood lactate, whereas section 2 (n = 17) completed blended laboratories for 1) maximal O2 consumption and 2) muscle electromyography. Both sections completed the same assignments (scored in a blinded manner using a standardized rubric) and practicum exams (evaluated by two independent investigators). Pre- and postcourse surveys were used to assess student perceptions. Most students (∼79%) watched videos for both blended laboratories. Assignment scores did not differ between blended and traditional laboratories (P = 0.62) or between sections (P = 0.91). Practicum scores did not differ between sections (both P > 0.05). At the end of the course, students' perceived value of the blended format increased (P physiology laboratories provided an alternative method for delivering content that was favorably perceived by students and did not compromise student performance. Copyright © 2016 The American Physiological Society.
13. Video Episodes and Action Cameras in the Undergraduate Chemistry Laboratory: Eliciting Student Perceptions of Meaningful Learning
Science.gov (United States)
Galloway, Kelli R.; Bretz, Stacey Lowery
2016-01-01
A series of quantitative studies investigated undergraduate students' perceptions of their cognitive and affective learning in the undergraduate chemistry laboratory. To explore these quantitative findings, a qualitative research protocol was developed to characterize student learning in the undergraduate chemistry laboratory. Students (N = 13)…
14. Designing an undergraduate laboratory course in general chemistry
Directory of Open Access Journals (Sweden)
Vianna José F.
1999-01-01
Full Text Available From an analysis of a learning model based on the theory of information processing four hypothesis were developed for improving the design of laboratory courses. Three of these hypotheses concerned specific procedures to minimise the load on students' working memories (or working spaces and the fourth hypothesis was concerned with the value of mini-projects in enhancing meaningful learning of the knowledge and skills underpinning the set experiments. A three-year study of a first year undergraduate chemistry laboratory course at a Scottish university has been carried out to test these four hypotheses. This paper reports the results of the study relevant to the three hypotheses about the burden on students' working spaces. It was predicted from the learning model that the load on students working space should be reduced by appropriate changes to the written instructions and the laboratory organisation and by the introduction of prelab-work and prelab-training in laboratory techniques. It was concluded from research conducted over the three years period that all these hypothesised changes were effective both in reducing the load on students' working spaces and in improving their attitudes to the laboratory course.
15. Evaluation of Thermo-Fluid Performance of Compact Heat Exchanger with Corrugated Wall Channels
International Nuclear Information System (INIS)
Tak, Nam Il; Lee, Won Jae
2006-01-01
One of the key components of an indirect nuclear hydrogen production system is an intermediate heat exchanger (IHX). For the IHX, a printed circuit heat exchanger (PCHE) is known as one of the promising types due to its compactness and ability to operate at high temperatures and under high pressures. The PCHE is a relatively new heat exchanger. It has been commercially manufactured only since 1985 and solely by one British vendor, HeatricTM. Due to its short history and limited production, sufficient information about the PCHE is not available for the design of the IHX in open literatures. The predominant shape of flow channels of the PCHE is laterally corrugated. The flow in a corrugated wall channel is very interesting since a variety of flow phenomena can be considered by changing the amplitude-to-wavelength ratio. In the present paper, thermo-fluid performance of a heat exchanger with a typical PCHE geometry has been evaluated. Computational fluid dynamics (CFD) analysis was performed to analyze a gas flow behavior in a corrugated wall channel
16. Thermo-fluid-dynamic modelling of a cold store for cheese maturation
Directory of Open Access Journals (Sweden)
Ferruccio Giametta
2013-03-01
Full Text Available In this study, drying tests on fresh cheeses were carried out in a cold store equipped with a Munters MG90 dehumidifier that controls the humidity of the room air. In this system, the condensation/drainage stage is omitted since the humid room air is directed out of the cold store (process air and the dried air is introduced by the dehumidifier inside the cold store. Eight air temperature probes were introduced in the store; two probes (HOBO U12-012, 1 HOBO – Onset Computer Corporation, Cape Cod, MA, USA were also introduced and used to measure relative humidity and temperature together with an anemometer to analyse any changes in thermal and fluid dynamics in the cell environment. COMSOL multiphysics software (Comsol Group, Stockolm, Sweden was used to simulate the store environment based on the finite elements method. This allowed us to compare and discuss the experimental data collected and the results obtained by the thermo- fluid-dynamic simulation.
17. PREFACE: 33rd UIT (Italian Union of Thermo-fluid dynamics) Heat Transfer Conference
Science.gov (United States)
Paoletti, Domenica; Ambrosini, Dario; Sfarra, Stefano
2015-11-01
The 33rd UIT (Italian Union of Thermo-Fluid Dynamics) Heat Transfer Conference was organized by the Dept. of Industrial and Information Engineering and Economics, University of L'Aquila (Italy) and was held at the Engineering Campus of Monteluco di Roio, L'Aquila, June 22-24, 2015. The annual UIT conference, which has grown over time, came back to L'Aquila after 21 years. The scope of the conference covers a range of major topics in theoretical, numerical and experimental heat transfer and related areas, ranging from energy efficiency to nuclear plants. This year, there was an emphasis on IR thermography, which is growing in importance both in scientific research and industrial applications. 2015 is also the International Year of Light. The Organizing Committee honored this event by introducing a new section, Technical Seminars, which in this edition was mainly devoted to optical flow visualization (also the subject of three different national workshops organized in L'Aquila by UIT in 2003, 2005 and 2008). The conference was held in the recently repaired Engineering buildings, six years after the 2009 earthquake and 50 years after the beginning of the Engineering courses in L'Aquila. Despite some logistical difficulties, 92 papers were submitted by about 270 authors, on eight different topics: heat transfer and efficiency in energy systems, environmental technologies and buildings (32 papers); micro and nano scale thermo-fluid dynamics (5 papers); multi-phase fluid dynamics, heat transfer and interface phenomena (16 papers); computational fluid dynamics and heat transfer (15 papers); heat transfer in nuclear plants (6 papers); natural, forced and mixed convection (6 papers); IR thermography (4 papers); conduction and radiation (3 papers). The conference program scheduled plenary, oral and poster sessions. The three invited plenary Keynote Lectures were given by Prof. Antonio Barletta (University of Bologna, Italy), Prof. Jean-Christophe Batsale (Arts et Metiers
18. Discovery of Escherichia coli CRISPR sequences in an undergraduate laboratory.
Science.gov (United States)
Militello, Kevin T; Lazatin, Justine C
2017-05-01
Clustered regularly interspaced short palindromic repeats (CRISPRs) represent a novel type of adaptive immune system found in eubacteria and archaebacteria. CRISPRs have recently generated a lot of attention due to their unique ability to catalog foreign nucleic acids, their ability to destroy foreign nucleic acids in a mechanism that shares some similarity to RNA interference, and the ability to utilize reconstituted CRISPR systems for genome editing in numerous organisms. In order to introduce CRISPR biology into an undergraduate upper-level laboratory, a five-week set of exercises was designed to allow students to examine the CRISPR status of uncharacterized Escherichia coli strains and to allow the discovery of new repeats and spacers. Students started the project by isolating genomic DNA from E. coli and amplifying the iap CRISPR locus using the polymerase chain reaction (PCR). The PCR products were analyzed by Sanger DNA sequencing, and the sequences were examined for the presence of CRISPR repeat sequences. The regions between the repeats, the spacers, were extracted and analyzed with BLASTN searches. Overall, CRISPR loci were sequenced from several previously uncharacterized E. coli strains and one E. coli K-12 strain. Sanger DNA sequencing resulted in the discovery of 36 spacer sequences and their corresponding surrounding repeat sequences. Five of the spacers were homologous to foreign (non-E. coli) DNA. Assessment of the laboratory indicates that improvements were made in the ability of students to answer questions relating to the structure and function of CRISPRs. Future directions of the laboratory are presented and discussed. © 2016 by The International Union of Biochemistry and Molecular Biology, 45(3):262-269, 2017. © 2016 The International Union of Biochemistry and Molecular Biology.
19. Development of sensorial experiments and their implementation into undergraduate laboratories
Science.gov (United States)
Bromfield Lee, Deborah Christina
"Visualization" of chemical phenomena often has been limited in the teaching laboratories to the sense of sight. We have developed chemistry experiments that rely on senses other than eyesight to investigate chemical concepts, make quantitative determinations, and familiarize students with chemical techniques traditionally designed using only eyesight. Multi-sensory learning can benefit all students by actively engaging them in learning through stimulation or an alternative way of experiencing a concept or ideas. Perception of events or concepts usually depends on the information from the different sensory systems combined. The use of multi-sensory learning can take advantage of all the senses to reinforce learning as each sense builds toward a more complete experience of scientific data. Research has shown that multi-sensory representations of scientific phenomena is a valuable tool for enhancing understanding of chemistry as well as displacing misconceptions through experience. Multi-sensory experiences have also been shown to enrich memory performance. There are few experiments published which utilize multiple senses in the teaching laboratory. The sensorial experiments chosen were conceptually similar to experiments currently performed in undergraduate laboratories; however students collect different types of data using multi-sensory observations. The experiments themselves were developed by using chemicals that would provide different sensory changes or capitalizing on sensory observations that were typically overlooked or ignored and obtain similar and precise results as in traditional experiments. Minimizing hazards and using safe practices are especially essential in these experiments as students utilize senses traditionally not allowed to be used in the laboratories. These sensorial experiments utilize typical equipment found in the teaching laboratories as well as inexpensive chemicals in order to aid implementation. All experiments are rigorously tested
20. Purification and Characterization of Taq Polymerase: A 9-Week Biochemistry Laboratory Project for Undergraduate Students
Science.gov (United States)
Bellin, Robert M.; Bruno, Mary K.; Farrow, Melissa A.
2010-01-01
We have developed a 9-week undergraduate laboratory series focused on the purification and characterization of "Thermus aquaticus" DNA polymerase (Taq). Our aim was to provide undergraduate biochemistry students with a full-semester continuing project simulating a research-like experience, while having each week's procedure focus on a single…
1. Method to Increase Undergraduate Laboratory Student Confidence in Performing Independent Research
Directory of Open Access Journals (Sweden)
Colton E. Kempton
2017-05-01
Full Text Available The goal of an undergraduate laboratory course should be not only to introduce the students to biology methodologies and techniques, but also to teach them independent analytical thinking skills and proper experiment design. This is especially true for advanced biology laboratory courses that undergraduate students typically take as a junior or senior in college. Many courses achieve the goal of teaching techniques, but fail to approach the larger goal of teaching critical thinking, experimental design, and student independence. Here we describe a study examining the application of the scaffolding instructional philosophy in which students are taught molecular techniques with decreasing guidance to force the development of analytical thinking skills and prepare undergraduate students for independent laboratory research. This method was applied to our advanced molecular biology laboratory class and resulted in an increase of confidence among the undergraduate students in their abilities to perform independent research.
2. The Quartz-Crystal Microbalance in an Undergraduate Laboratory Experiment: I. Fundamentals and Instrumentation
Science.gov (United States)
2007-01-01
The fundamentals, as well as the instrumentation of the quartz-crystal microbalance (QCM) technique that is used in an undergraduate laboratory experiment are being described. The QCM response can be easily used to change the properties of any system.
3. Determination of Rate Constants for Ouabain Inhibition of Adenosine Triphosphatase: An Undergraduate Biological Chemistry Laboratory Experiment
Science.gov (United States)
Sall, Eri; And Others
1978-01-01
Describes an undergraduate biological chemistry laboratory experiment which provides students with an example of pseudo-first-order kinetics with the cardiac glycoside inhibition of mammalism sodium and potassium transport. (SL)
4. Measuring Meaningful Learning in the Undergraduate Chemistry Laboratory: A National, Cross-Sectional Study
Science.gov (United States)
Galloway, Kelli R.; Bretz, Stacey Lowery
2015-01-01
Research on laboratory learning points to the need to better understand what and how students learn in the undergraduate chemistry laboratory. The Meaningful Learning in the Laboratory Instrument (MLLI) was administered to general and organic chemistry students from 15 colleges and universities across the United States in order to measure the…
5. Measuring Meaningful Learning in the Undergraduate General Chemistry and Organic Chemistry Laboratories: A Longitudinal Study
Science.gov (United States)
Galloway, Kelli R.; Bretz, Stacey Lowery
2015-01-01
Understanding how students learn in the undergraduate chemistry teaching laboratory is an essential component to developing evidence-based laboratory curricula. The Meaningful Learning in the Laboratory Instrument (MLLI) was developed to measure students' cognitive and affective expectations and experiences for learning in the chemistry…
6. Known Structure, Unknown Function: An Inquiry-Based Undergraduate Biochemistry Laboratory Course
Science.gov (United States)
Gray, Cynthia; Price, Carol W.; Lee, Christopher T.; Dewald, Alison H.; Cline, Matthew A.; McAnany, Charles E.; Columbus, Linda; Mura, Cameron
2015-01-01
Undergraduate biochemistry laboratory courses often do not provide students with an authentic research experience, particularly when the express purpose of the laboratory is purely instructional. However, an instructional laboratory course that is inquiry- and research-based could simultaneously impart scientific knowledge and foster a student's…
7. A Laboratory Course for Teaching Laboratory Techniques, Experimental Design, Statistical Analysis, and Peer Review Process to Undergraduate Science Students
Science.gov (United States)
Gliddon, C. M.; Rosengren, R. J.
2012-01-01
This article describes a 13-week laboratory course called Human Toxicology taught at the University of Otago, New Zealand. This course used a guided inquiry based laboratory coupled with formative assessment and collaborative learning to develop in undergraduate students the skills of problem solving/critical thinking, data interpretation and…
8. An undergraduate laboratory exercise examining the psychomotor stimulant effects of caffeine in laboratory rats.
Science.gov (United States)
Pham, Kara; Romeo, Russell D
2012-01-01
This paper describes an exercise in a Systems and Behavioral Neuroscience with Laboratory class, an introductory laboratory class taken by Barnard College students majoring in a wide range of academic topics. The study took place over three weeks, allowing students to assess the effects of caffeine on motor stimulation in laboratory rats. The within-subject design involved injecting rats with three different caffeine doses and measuring five different motor outputs in a standard open field. Students completed four different assignments related to this study, demonstrating acquisition of the stated learning goals. This lab exercise allowed students to learn about basal ganglia neural circuitry and stimulant pharmacology, to work directly with an animal model, and to generate enough data to perform statistical analyses. Course evaluations suggest that students liked learning about caffeine, a stimulant many of them have personal experience consuming. They also expressed appreciation for working with rats and for learning how to analyze data. This study can easily be implemented at most undergraduate institutions under minimal cost. The wide-ranging effects of caffeine also permit for flexibility in experimental design, allowing instructors and students options for different avenues of investigation.
9. Undergraduate Laboratory Experiment Modules for Probing Gold Nanoparticle Interfacial Phenomena
Science.gov (United States)
Karunanayake, Akila G.; Gunatilake, Sameera R.; Ameer, Fathima S.; Gadogbe, Manuel; Smith, Laura; Mlsna, Deb; Zhang, Dongmao
2015-01-01
Three gold-nanoparticle (AuNP) undergraduate experiment modules that are focused on nanoparticles interfacial phenomena have been developed. Modules 1 and 2 explore the synthesis and characterization of AuNPs of different sizes but with the same total gold mass. These experiments enable students to determine how particle size affects the AuNP…
10. Aza-Michael Reaction for an Undergraduate Organic Chemistry Laboratory
Science.gov (United States)
Nigam, Manisha; Rush, Brittney; Patel, Jay; Castillo, Raul; Dhar, Preeti
2016-01-01
A green, aza-Michael reaction is described that can be used to teach undergraduate students conjugate addition of nitrogen nucleophile to an a,ß-unsaturated ester. Students analyze spectral data of the product obtained from the assigned reaction to determine product structure and propose the mechanism of its formation. The experiment requires…
11. Determination of Sulfate by Conductometric Titration: An Undergraduate Laboratory Experiment
Science.gov (United States)
Garcia, Jennifer; Schultz, Linda D.
2016-01-01
The classic technique for sulfate analysis in an undergraduate quantitative analysis lab involves precipitation as the barium salt with barium chloride, collection of the precipitate by gravity filtration using ashless filter paper, and removal of the filter paper by charring over a Bunsen burner. The entire process is time-consuming, hazardous,…
Science.gov (United States)
Franco-Villafañe, J. A.; Flores-Olmedo, E.; Báez, G.; Gandarilla-Carrillo, O.; Méndez-Sánchez, R. A.
2012-11-01
We present a simple experiment that allows advanced undergraduates to learn the principles and applications of spectroscopy. The technique, known as acoustic resonance spectroscopy, is applied to study a vibrating rod. The setup includes electromagnetic-acoustic transducers, an audio amplifier and a vector network analyzer. Typical results of compressional, torsional and bending waves are analyzed and compared with analytical results.
13. Green Chemistry Decision-Making in an Upper-Level Undergraduate Organic Laboratory
Science.gov (United States)
Edgar, Landon J. G.; Koroluk, Katherine J.; Golmakani, Mehrnaz; Dicks, Andrew P.
2014-01-01
A self-directed independent synthesis experiment was developed for a third-year undergraduate organic laboratory. Students were provided with the CAS numbers of starting and target compounds and devised a synthetic plan to be executed over two 4.5 h laboratory periods. They consulted the primary literature in order to develop and carry out an…
14. Hairy Root as a Model System for Undergraduate Laboratory Curriculum and Research
Science.gov (United States)
Keyes, Carol A.; Subramanian, Senthil; Yu, Oliver
2009-01-01
Hairy root transformation has been widely adapted in plant laboratories to rapidly generate transgenic roots for biochemical and molecular analysis. We present hairy root transformations as a versatile and adaptable model system for a wide variety of undergraduate laboratory courses and research. This technique is easy, efficient, and fast making…
15. A Survey of the Practices, Procedures, and Techniques in Undergraduate Organic Chemistry Teaching Laboratories
Science.gov (United States)
Martin, Christopher B.; Schmidt, Monica; Soniat, Michael
2011-01-01
A survey was conducted of four-year institutions that teach undergraduate organic chemistry laboratories in the United States. The data include results from over 130 schools, describes the current practices at these institutions, and discusses the statistical results such as the scale of the laboratories performed, the chemical techniques applied,…
16. Spectroscopy 101: A Practical Introduction to Spectroscopy and Analysis for Undergraduate Organic Chemistry Laboratories
Science.gov (United States)
Morrill, Lucas A.; Kammeyer, Jacquelin K.; Garg, Neil K.
2017-01-01
An undergraduate organic chemistry laboratory that provides an introduction to various spectroscopic techniques is reported. Whereas organic spectroscopy is most often learned and practiced in the context of reaction analyses, this laboratory experiment allows students to become comfortable with [superscript 1]H NMR, [superscript 13]C NMR, and IR…
17. An Undergraduate Laboratory Experiment in Bioinorganic Chemistry: Ligation States of Myoglobin
Science.gov (United States)
Bailey, James A.
2011-01-01
Although there are numerous inorganic model systems that are readily presented as undergraduate laboratory experiments in bioinorganic chemistry, there are few examples that explore the inorganic chemistry of actual biological molecules. We present a laboratory experiment using the oxygen-binding protein myoglobin that can be easily incorporated…
18. Green Fluorescent Protein-Focused Bioinformatics Laboratory Experiment Suitable for Undergraduates in Biochemistry Courses
Science.gov (United States)
Rowe, Laura
2017-01-01
An introductory bioinformatics laboratory experiment focused on protein analysis has been developed that is suitable for undergraduate students in introductory biochemistry courses. The laboratory experiment is designed to be potentially used as a "stand-alone" activity in which students are introduced to basic bioinformatics tools and…
19. A Comprehensive Microfluidics Device Construction and Characterization Module for the Advanced Undergraduate Analytical Chemistry Laboratory
Science.gov (United States)
Piunno, Paul A. E.; Zetina, Adrian; Chu, Norman; Tavares, Anthony J.; Noor, M. Omair; Petryayeva, Eleonora; Uddayasankar, Uvaraj; Veglio, Andrew
2014-01-01
An advanced analytical chemistry undergraduate laboratory module on microfluidics that spans 4 weeks (4 h per week) is presented. The laboratory module focuses on comprehensive experiential learning of microfluidic device fabrication and the core characteristics of microfluidic devices as they pertain to fluid flow and the manipulation of samples.…
20. Upper-Level Undergraduate Chemistry Students' Goals for Their Laboratory Coursework
Science.gov (United States)
DeKorver, Brittland K.; Towns, Marcy H.
2016-01-01
Efforts to reform undergraduate chemistry laboratory coursework typically focus on the curricula of introductory-level courses, while upper-level courses are bypassed. This study used video-stimulated recall to interview 17 junior- and senior- level chemistry majors after they carried out an experiment as part of a laboratory course. It is assumed…
DEFF Research Database (Denmark)
Pelzmann, Sabine; Winkler, Ingo
2014-01-01
This article reports on a leadership laboratory provided as an elective within a Bachelor degree programme in Business Administration. The core understanding of this laboratory was that people can learn leadership. Moreover, the laboratory built on the assumption that an experienced-based approach...... to learn about leadership offers many advantages to leadership novices, in this case students without prior work experience....
DEFF Research Database (Denmark)
Pelzmann, Sabine; Winkler, Ingo
2014-01-01
This article reports on a leadership laboratory provided as an elective within a Bachelor degree programme in Business Administration. The core understanding of this laboratory was that people can learn leadership. Moreover, the laboratory built on the assumption that an experienced-based approac...
3. Creative Report Writing in Undergraduate Organic Chemistry Laboratory Inspires Nonmajors
Science.gov (United States)
Henary, Maged; Owens, Eric A.; Tawney, Joseph G.
2015-01-01
Laboratory-based courses require students to compose reports based on the performed experiments to assess their overall understanding of the presented material; unfortunately, the sterile and formulated nature of the laboratory report disinterests most students. As a result, the outcome is a lower-quality product that does not reveal full…
4. Assessing Practical Laboratory Skills in Undergraduate Molecular Biology Courses
Science.gov (United States)
Hunt, Lynne; Koenders, Annette; Gynnild, Vidar
2012-01-01
This study explored a new strategy of assessing laboratory skills in a molecular biology course to improve: student effort in preparation for and participation in laboratory work; valid evaluation of learning outcomes; and students' employment prospects through provision of evidence of their skills. Previously, assessment was based on written…
5. Optical Beam Deflection Based AFM with Integrated Hardware and Software Platform for an Undergraduate Engineering Laboratory
Directory of Open Access Journals (Sweden)
Siu Hong Loh
2017-02-01
Full Text Available Atomic force microscopy (AFM has been used extensively in nanoscience research since its invention. Recently, many teaching laboratories in colleges, undergraduate institutions, and even high schools incorporate AFM as an effective teaching tool for nanoscience education. This paper presents an optical beam deflection (OBD based atomic force microscope, designed specifically for the undergraduate engineering laboratory as a teaching instrument. An electronic module for signal conditioning was built with components that are commonly available in an undergraduate electronic laboratory. In addition to off-the-shelf mechanical parts and optics, the design of custom-built mechanical parts waskept as simple as possible. Hence, the overall cost for the setup is greatly reduced. The AFM controller was developed using National Instruments Educational Laboratory Virtual Instrumentation Suite (NI ELVIS, an integrated hardware and software platform which can be programmed in LabVIEW. A simple yet effective control algorithm for scanning and feedback control was developed. Despite the use of an educational platform and low-cost components from the undergraduate laboratory, the developed AFM is capable of performing imaging in constant-force mode with submicron resolution and at reasonable scanning speed (approximately 18 min per image. Therefore, the AFM is suitable to be used as an educational tool for nanoscience. Moreover, the construction of the system can be a valuable educational experience for electronic and mechanical engineering students.
6. Practicing biology: Undergraduate laboratory research, persistence in science, and the impact of self-efficacy beliefs
Science.gov (United States)
Berkes, Elizabeth
As undergraduate laboratory research internships become more popular and universities devote considerable resources towards promoting them, it is important to clarify what students specifically gain through involvement in these experiences and it is important to understand their impact on the science pipeline. By examining recent findings describing the primary benefits of undergraduate research participation, along with self-efficacy theory, this study aims to provide more explanatory power to the anecdotal and descriptive accounts regarding the relationship between undergraduate research experiences and interest in continuing in science. Furthermore, this study characterizes practices that foster students' confidence in doing scientific work with detailed description and analysis of the interactions of researchers in a laboratory. Phase 1 of the study, a survey of undergraduate biology majors (n=71) at a major research university, investigates the relationships among participation in biology laboratory research internships, biology laboratory self-efficacy strength, and interest in persisting in science. Phase 2 of the study, a two-year investigation of a university biology research laboratory, investigates how scientific communities of practice develop self-efficacy beliefs. The findings suggest that participation in lab internships results in increased interest in continuing in life science/biology graduate school and careers. They also suggest that a significant proportion of that interest is related to the students' biology laboratory self-efficacy. The findings of this study point to two primary ways that undergraduate research participation might work to raise self-efficacy strength. First, university research laboratory communities can provide students with a variety of resources that scaffold them into biology laboratory mastery experiences. Second, university research laboratory communities can provide students with coping and mastery Discourse models
7. Kimchi: Spicy Science for the Undergraduate Microbiology Laboratory
Directory of Open Access Journals (Sweden)
Virginia A. Young
2014-02-01
Full Text Available Undergraduate microbiology courses offer a perfect opportunity to introduce students to historical food preservation processes that are still in use today. The fermentation of vegetables, as occurs in the preparation of sauerkraut and kimchi, uses an enrichment step to select for the growth of naturally occurring lactic acid bacteria (LAB. This is an active learning exercise in which students learn a food preparation skill and basic microbiological terms such as selection and enrichment. When performed in conjunction with cultured fermentations, such as yogurt making, students can see the difference between fermentations by naturally occurring microorganisms versus inoculated microorganisms. Additionally, this exercise introduces students to concepts of food safety, intrinsic factors influencing microbial growth such as pH, and cultural uses of fermentation to preserve locally available foods.
8. Developing a Computer Laboratory for Undergraduate Sociology Courses.
Science.gov (United States)
Raymondo, James C.
1996-01-01
Discusses the development of a computer laboratory for sociology courses, as well as some advantages and disadvantages of incorporating computer technology into the classroom. Examines the proposal and proposal-review process. Provides tips for writing a successful proposal. (MJP)
9. Bring Your Own Device: A Digital Notebook for Undergraduate Biochemistry Laboratory Using a Free, Cross-Platform Application
Science.gov (United States)
Van Dyke, Aaron R.; Smith-Carpenter, Jillian
2017-01-01
The majority of undergraduates own a smartphone, yet fewer than half view it as a valuable learning technology. Consequently, a digital laboratory notebook (DLN) was developed for an upper-division undergraduate biochemistry laboratory course using the free mobile application Evernote. The cloud-based DLN capitalized on the unique features of…
10. Anisotropic Rotational Diffusion Studied by Nuclear Spin Relaxation and Molecular Dynamics Simulation: An Undergraduate Physical Chemistry Laboratory
Science.gov (United States)
Fuson, Michael M.
2017-01-01
Laboratories studying the anisotropic rotational diffusion of bromobenzene using nuclear spin relaxation and molecular dynamics simulations are described. For many undergraduates, visualizing molecular motion is challenging. Undergraduates rarely encounter laboratories that directly assess molecular motion, and so the concept remains an…
11. Development of an Assessment Tool to Measure Students' Meaningful Learning in the Undergraduate Chemistry Laboratory
Science.gov (United States)
Galloway, Kelli R.; Bretz, Stacey Lowery
2015-01-01
Research on learning in the undergraduate chemistry laboratory necessitates an understanding of students' perspectives of learning. Novak's Theory of Meaningful Learning states that the cognitive (thinking), affective (feeling), and psychomotor (doing) domains must be integrated for meaningful learning to occur. The psychomotor domain is the…
12. A Static Method as an Alternative to Gel Chromatography: An Experiment for the Undergraduate Biochemistry Laboratory
Science.gov (United States)
Burum, Alex D.; Splittgerber, Allan G.
2008-01-01
This article describes a static method as an alternative to gel chromatography, which may be used as an undergraduate laboratory experiment. In this method, a constant mass of Sephadex gel is swollen in a series of protein solutions. UV-vis spectrophotometry is used to find a partition coefficient, KD, that indicates the fraction of the interior…
13. An Integrated Visualization and Basic Molecular Modeling Laboratory for First-Year Undergraduate Medicinal Chemistry
Science.gov (United States)
Hayes, Joseph M.
2014-01-01
A 3D model visualization and basic molecular modeling laboratory suitable for first-year undergraduates studying introductory medicinal chemistry is presented. The 2 h practical is embedded within a series of lectures on drug design, target-drug interactions, enzymes, receptors, nucleic acids, and basic pharmacokinetics. Serving as a teaching aid…
14. Student Perceptions of the Cell Biology Laboratory Learning Environment in Four Undergraduate Science Courses in Spain
Science.gov (United States)
De Juan, Joaquin; Pérez-Cañaveras, Rosa M.; Segovia, Yolanda; Girela, Jose Luis; Martínez-Ruiz, Noemi; Romero-Rameta, Alejandro; Gómez-Torres, Maria José; Vizcaya-Moreno, M. Flores
2016-01-01
Cell biology is an academic discipline that organises and coordinates the learning of the structure, function and molecular composition of cells in some undergraduate biomedical programs. Besides course content and teaching methodologies, the laboratory environment is considered a key element in the teaching of and learning of cell biology. The…
15. Investigation of Macrophage Differentiation and Cytokine Production in an Undergraduate Immunology Laboratory
Science.gov (United States)
Berkes, Charlotte; Chan, Leo Li-Ying
2015-01-01
We have developed a semester-long laboratory project for an undergraduate immunology course in which students study multiple aspects of macrophage biology including differentiation from progenitors in the bone marrow, activation upon stimulation with microbial ligands, expression of cell surface markers, and modulation of cytokine production. In…
16. An Undergraduate Course and Laboratory in Digital Signal Processing with Field Programmable Gate Arrays
Science.gov (United States)
Meyer-Base, U.; Vera, A.; Meyer-Base, A.; Pattichis, M. S.; Perry, R. J.
2010-01-01
In this paper, an innovative educational approach to introducing undergraduates to both digital signal processing (DSP) and field programmable gate array (FPGA)-based design in a one-semester course and laboratory is described. While both DSP and FPGA-based courses are currently present in different curricula, this integrated approach reduces the…
17. Forensic Analysis of Canine DNA Samples in the Undergraduate Biochemistry Laboratory
Science.gov (United States)
Carson, Tobin M.; Bradley, Sharonda Q.; Fekete, Brenda L.; Millard, Julie T.; LaRiviere, Frederick J.
2009-01-01
Recent advances in canine genomics have allowed the development of highly distinguishing methods of analysis for both nuclear and mitochondrial DNA. We describe a laboratory exercise suitable for an undergraduate biochemistry course in which the polymerase chain reaction is used to amplify hypervariable regions of DNA from dog hair and saliva…
18. Understanding Our Energy Footprint: Undergraduate Chemistry Laboratory Investigation of Environmental Impacts of Solid Fossil Fuel Wastes
Science.gov (United States)
Berger, Michael; Goldfarb, Jillian L.
2017-01-01
Engaging undergraduates in the environmental consequences of fossil fuel usage primes them to consider their own anthropogenic impact, and the benefits and trade-offs of converting to renewable fuel strategies. This laboratory activity explores the potential contaminants (both inorganic and organic) present in the raw fuel and solid waste…
19. An Advanced Undergraduate Chemistry Laboratory Experiment Exploring NIR Spectroscopy and Chemometrics
Science.gov (United States)
Wanke, Randall; Stauffer, Jennifer
2007-01-01
An advanced undergraduate chemistry laboratory experiment to study the advantages and hazards of the coupling of NIR spectroscopy and chemometrics is described. The combination is commonly used for analysis and process control of various ingredients used in agriculture, petroleum and food products.
20. Peer Mentor Program for the General Chemistry Laboratory Designed to Improve Undergraduate STEM Retention
Science.gov (United States)
Damkaci, Fehmi; Braun, Timothy F.; Gublo, Kristin
2017-01-01
We describe the design and implementation of an undergraduate peer mentor program that can overlay an existing general chemistry laboratory and is designed to improve STEM student retention. For the first four freshman cohorts going through the program, year-to-year retention improved by a four-year average of 20% for students in peer-mentored…
1. Transitioning from Expository Laboratory Experiments to Course-Based Undergraduate Research in General Chemistry
Science.gov (United States)
Clark, Ted M.; Ricciardo, Rebecca; Weaver, Tyler
2016-01-01
General chemistry courses predominantly use expository experiments that shape student expectations of what a laboratory activity entails. Shifting within a semester to course-based undergraduate research activities that include greater decision-making, collaborative work, and "messy" real-world data necessitates a change in student…
2. Glucose Transport in Cultured Animal Cells: An Exercise for the Undergraduate Cell Biology Laboratory
Science.gov (United States)
Ledbetter, Mary Lee S.; Lippert, Malcolm J.
2002-01-01
Membrane transport is a fundamental concept that undergraduate students of cell biology understand better with laboratory experience. Formal teaching exercises commonly used to illustrate this concept are unbiological, qualitative, or intricate and time consuming to prepare. We have developed an exercise that uses uptake of radiolabeled nutrient…
3. Purification and Characterization of Enzymes from Yeast: An Extended Undergraduate Laboratory Sequence for Large Classes
Science.gov (United States)
Johanson, Kelly E.; Watt, Terry J.; McIntyre, Neil R.; Thompson, Marleesa
2013-01-01
Providing a project-based experience in an undergraduate biochemistry laboratory class can be complex with large class sizes and limited resources. We have designed a 6-week curriculum during which students purify and characterize the enzymes invertase and phosphatase from bakers yeast. Purification is performed in two stages via ethanol…
4. 3D Printing of Protein Models in an Undergraduate Laboratory: Leucine Zippers
Science.gov (United States)
Meyer, Scott C.
2015-01-01
An upper-division undergraduate laboratory experiment is described that explores the structure/function relationship of protein domains, namely leucine zippers, through a molecular graphics computer program and physical models fabricated by 3D printing. By generating solvent accessible surfaces and color-coding hydrophobic, basic, and acidic amino…
5. Small Laccase from "Streptomyces Coelicolor"--An Ideal Model Protein/Enzyme for Undergraduate Laboratory Experience
Science.gov (United States)
Cook, Ryan; Hannon, Drew; Southard, Jonathan N.; Majumdar, Sudipta
2018-01-01
A one semester undergraduate biochemistry laboratory experience is described for an understanding of recombinant technology from gene cloning to protein characterization. An integrated experimental design includes three sequential modules: molecular cloning, protein expression and purification, and protein analysis and characterization. Students…
6. Incorporation of Gas Chromatography-Mass Spectrometry into the Undergraduate Organic Chemistry Laboratory Curriculum
Science.gov (United States)
Giarikos, Dimitrios G.; Patel, Sagir; Lister, Andrew; Razeghifard, Reza
2013-01-01
Gas chromatography-mass spectrometry (GC-MS) is a powerful analytical tool for detection, identification, and quantification of many volatile organic compounds. However, many colleges and universities have not fully incorporated this technique into undergraduate teaching laboratories despite its wide application and ease of use in organic…
7. Testing Plastic Deformations of Materials in the Introductory Undergraduate Mechanics Laboratory
Science.gov (United States)
Romo-Kroger, C. M.
2012-01-01
Normally, a mechanics laboratory at the undergraduate level includes an experiment to verify compliance with Hooke's law in materials, such as a steel spring and an elastic rubber band. Stress-strain curves are found for these elements. Compression in elastic bands is practically impossible to achieve due to flaccidity. A typical experiment for…
8. Making Microscopy Motivating, Memorable, & Manageable for Undergraduate Students with Digital Imaging Laboratories
Science.gov (United States)
Weeks, Andrea; Bachman. Beverly; Josway, Sarah; North, Brittany; Tsuchiya, Mirian T.N.
2013-01-01
Microscopy and precise observation are essential skills that are challenging to teach effectively to large numbers of undergraduate biology students. We implemented student-driven digital imaging assignments for microscopy in a large enrollment laboratory for organismal biology. We detail how we promoted student engagement with the material and…
9. Comparing Amide-Forming Reactions Using Green Chemistry Metrics in an Undergraduate Organic Laboratory
Science.gov (United States)
Fennie, Michael W.; Roth, Jessica M.
2016-01-01
In this laboratory experiment, upper-division undergraduate chemistry and biochemistry majors investigate amide-bond-forming reactions from a green chemistry perspective. Using hydrocinnamic acid and benzylamine as reactants, students perform three types of amide-forming reactions: an acid chloride derivative route; a coupling reagent promoted…
10. Cross-Disciplinary Thermoregulation and Sweat Analysis Laboratory Experiences for Undergraduate Chemistry and Exercise Science Students
Science.gov (United States)
Mulligan, Gregory; Taylor, Nichole; Glen, Mary; Tomlin, Dona; Gaul, Catherine A.
2011-01-01
Cross-disciplinary (CD) learning experiences benefit student understanding of concepts and curriculum by offering opportunities to explore topics from the perspectives of alternate fields of study. This report involves a qualitative evaluation of CD health sciences undergraduate laboratory experiences in which concepts and students from two…
11. Analyzing Exonuclease-Induced Hyperchromicity by Uv Spectroscopy: An Undergraduate Biochemistry Laboratory Experiment
Science.gov (United States)
Ackerman, Megan M.; Ricciardi, Christopher; Weiss, David; Chant, Alan; Kraemer-Chant, Christina M.
2016-01-01
An undergraduate biochemistry laboratory experiment is described that utilizes free online bioinformatics tools along with readily available exonucleases to study the effects of base stacking and hydrogen bonding on the UV absorbance of DNA samples. UV absorbance of double-stranded DNA at the ?[subscript max] is decreased when the DNA bases are…
12. A Measure of the Effectiveness of Incorporating 3D Human Anatomy into an Online Undergraduate Laboratory
Science.gov (United States)
2009-01-01
Results of a study designed to determine the effectiveness of implementing three-dimensional (3D) stereo images of a human skull in an undergraduate human anatomy online laboratory were gathered and analysed. Mental model theory and its applications to 3D relationships are discussed along with the research results. Quantitative results on 62 pairs…
13. Computation of Chemical Shifts for Paramagnetic Molecules: A Laboratory Experiment for the Undergraduate Curriculum
Science.gov (United States)
Pritchard, Benjamin P.; Simpson, Scott; Zurek, Eva; Autschbach, Jochen
2014-01-01
A computational experiment investigating the [superscript 1]H and [superscript 13]C nuclear magnetic resonance (NMR) chemical shifts of molecules with unpaired electrons has been developed and implemented. This experiment is appropriate for an upper-level undergraduate laboratory course in computational, physical, or inorganic chemistry. The…
14. What are undergraduates doing at biological field stations and marine laboratories?
Science.gov (United States)
Janet Hodder
2009-01-01
Biological field stations and marine laboratories (FSMLs) serve as places to study the natural environment in a variety of ways, from the level of the molecule to the globe. Undergraduate opportunities at FSMLs reflect the diversity of study options -- formal courses, research and service internships, and field-trip experiences -- and students are responding to those...
15. The Quartz-Crystal Microbalance in an Undergraduate Laboratory Experiment: Measuring Mass
Science.gov (United States)
2007-01-01
The study explains the quartz-crystal microbalance (QCM) technique, which is often used as an undergraduate laboratory experiment for measuring the mass of a system. QCM can be used as a mass sensor only when the measured mass is rigidly attached to the surface.
16. High-Performance Liquid Chromatography in the Undergraduate Chemical Engineering Laboratory
Science.gov (United States)
Frey, Douglas D.; Guo, Hui; Karnik, Nikhila
2013-01-01
This article describes the assembly of a simple, low-cost, high-performance liquid chromatography (HPLC) system and its use in the undergraduate chemical engineering laboratory course to perform simple experiments. By interpreting the results from these experiments students are able to gain significant experience in the general method of…
17. Incorporating Course-Based Undergraduate Research Experiences into Analytical Chemistry Laboratory Curricula
Science.gov (United States)
Kerr, Melissa A.; Yan, Fei
2016-01-01
A continuous effort within an undergraduate university setting is to improve students' learning outcomes and thus improve students' attitudes about a particular field of study. This is undoubtedly relevant within a chemistry laboratory. This paper reports the results of an effort to introduce a problem-based learning strategy into the analytical…
18. Integrating Bio-Inorganic and Analytical Chemistry into an Undergraduate Biochemistry Laboratory
Science.gov (United States)
Erasmus, Daniel J.; Brewer, Sharon E.; Cinel, Bruno
2015-01-01
Undergraduate laboratories expose students to a wide variety of topics and techniques in a limited amount of time. This can be a challenge and lead to less exposure to concepts and activities in bio-inorganic chemistry and analytical chemistry that are closely-related to biochemistry. To address this, we incorporated a new iron determination by…
19. The Perceptions, Views and Opinions of University Students about Physics Learning during Undergraduate Laboratory Work
Science.gov (United States)
Hanif, M.; Sneddon, P. H.; Al-Ahmadi, F. M.; Reid, N.
2009-01-01
The physics laboratory has long been a distinctive feature of physics education. It has been given a central role in the teaching and learning of physics at school and undergraduate levels in universities. The literature indicates that science educators have suggested that there are academically rich benefits in the learning and understanding of…
20. A Green Polymerization of Aspartic Acid for the Undergraduate Organic Laboratory
Science.gov (United States)
Bennett, George D.
2005-01-01
The green polymerization of aspartic acid carried out during an organic-inorganic synthesis laboratory course for undergraduate students is described. The procedure is based on work by Donlar Corporation, a Peru, Illinois-based company that won a Green Chemistry Challenge Award in 1996 in the Small Business category for preparing thermal…
1. Thermo-fluid dynamics and corrosion analysis of a self cooled lead lithium blanket for the HiPER reactor
Science.gov (United States)
Juárez, R.; Zanzi, C.; Hernández, J.; Sanz, J.
2015-09-01
The HiPER reactor is the HiPER project phase devoted to power production. To reach a preliminary reactor design, tritium breeding schemes need to be adapted to the HiPER project technologies selection: direct drive ignition, 150 \\text{MJ}/\\text{shot}× 10 Hz of power released through fusion reactions, and the dry first wall scheme. In this paper we address the main challenge of the HiPER EUROFER-based self cooled lead lithium blanket, which is related to the corrosive behavior of Pb-15.7Li in contact with EUROFER. We evaluate the cooling and corrosion behavior of the so-called separated first wall blanket (SFWB) configuration by performing thermo-fluid dynamics simulations using a large eddy simulation approach. Despite the expected improvement over the integrated first wall blanket, we still find an unsatisfactory cooling performance, expressed as a low outlet Pb-15.7Li temperature plus too high corrosion rates derived from local Pb-15.7Li high temperature and velocity, which can mainly be attributed to the geometry of the channels. Nevertheless, the analysis allowed us to devise future modifications of the SFWB to overcome the limitations found with the present design.
2. Integrated thermo-fluid analysis towards helium flow path design for an ITER solid breeder blanket module
International Nuclear Information System (INIS)
Ying, A.; Narula, M.; Hunt, R.; Abdou, M.; Ando, Y.; Komada, I.
2007-01-01
The successful design and development of a complex system, like the ITER test blanket module (TBM) warrants the need of extensive computer aided engineering (CAE) activities. In this light, a sophisticated numerical flow solver ('SC/Tetra' by CRADLE), with a robust CAD interface, has been used to develop and evaluate helium coolant flow schemes for a solid breeder test blanket module design currently proposed by the US for testing in ITER. The traits of a particular cooling strategy for the TBM, namely the exit temperature of coolant, overall pressure drop, uniformity of temperature in the structure, robustness against transients, etc. can only be predicted by carrying out a complete three dimensional thermal-fluid analysis of the system in its entirety including all the structural and fluid components. The primary objective of this paper is to introduce the procedure for carrying out complex thermo-fluid analysis using the complete three dimensional CAD models of the TBM to evaluate the performance of TBM cooling schemes and to illustrate the way in which the results from these analyses can be useful towards a systematic design of an effective cooling solution for the test blanket module
3. The PASCO Wireless Smart Cart: A Game Changer in the Undergraduate Physics Laboratory
Science.gov (United States)
Shakur, Asif; Connor, Rainor
2018-03-01
With the introduction of the Wireless Smart Cart by PASCO scientific in April 2016, we expect a paradigm shift in undergraduate physics laboratory instruction. We have evaluated the feasibility of using the smart cart by carrying out experiments that are usually performed using traditional PASCO equipment. The simplicity, convenience, and cost-saving achieved by replacing a plethora of traditional laboratory sensors, wires, and equipment clutter with the smart cart are reported here.
4. Vectors and Fomites: An Investigative Laboratory for Undergraduates.
Science.gov (United States)
Adamo, Joseph A.; Gealt, Michael A.
1996-01-01
Presents a laboratory model system for introductory microbiology students that involves hands-on studies of bacteria vectored in soil nematodes. Describes a series of experiments designed to demonstrate vector-fomite transmission, bacterial survival, and disinfectant activity. Introduces the concept of genetically engineered microorganisms and the…
5. An Enzyme Kinetics Experiment for the Undergraduate Organic Chemistry Laboratory
Science.gov (United States)
Olsen, Robert J.; Olsen, Julie A.; Giles, Greta A.
2010-01-01
An experiment using [superscript 1]H NMR spectroscopy to observe the kinetics of the acylase 1-catalyzed hydrolysis of "N"-acetyl-DL-methionine has been developed for the organic laboratory. The L-enantiomer of the reactant is hydrolyzed completely in less than 2 h, and [superscript 1]H NMR spectroscopic data from a single sample can be worked up…
6. Common Learning Objectives for Undergraduate Control Systems Laboratories
Science.gov (United States)
Reck, Rebecca M.
2017-01-01
Course objectives, like research objectives and product requirements, help provide clarity and direction for faculty and students. Unfortunately, course and laboratory objectives are not always clearly stated. Without a clear set of objectives, it can be hard to design a learning experience and determine whether students are achieving the intended…
7. Glycosidation of Methanol with Ribose: An Interdisciplinary Undergraduate Laboratory Experiment
Science.gov (United States)
Simon, Erin; Cook, Katie; Pritchard, Meredith R.; Stripe, Wayne; Bruch, Martha; Bendinskas, Kestutis
2010-01-01
This exercise provides students hands-on experience with the topics of glycosidation, hemiacetal and acetal formation, proton nuclear magnetic resonance ([superscript 1]H NMR) spectroscopy, and kinetic and thermodynamic product formation. In this laboratory experiment, the methyl acetal of ribose is synthesized, and the kinetic and thermodynamic…
8. Commentary: Why Abandoning Undergraduate Laboratories Is Not an Option
Science.gov (United States)
Costa, Manuel Joao
2010-01-01
Laboratory exercises (labs) are sometimes regarded as dispensable in biochemistry and molecular biology (BMB) education for various reasons including a combination of increased class costs and small budget allocations, pressing demands for more time to lecture to fit in new BMB discoveries within constant time span of courses, and the fact that…
9. Laboratory Safety Awareness Among General Physics Undergraduate Students
Directory of Open Access Journals (Sweden)
2017-12-01
Full Text Available Safety awareness in the laboratory is essential to reduce occupational risks. This study was conducted to determine the students’ safety awareness in a Physics laboratory. This study determined the student perception towards safety awareness by factors of gender and college from which students are enrolled. A sum of 324 students enrolled in Physics10 (Mechanics and Heat and Physics11 (Electricity and Magnetism in the Mindanao University of Science and Technology (MUST were randomly selected as survey respondents. A modified survey questionnaire was used as research instrument. The results show that the students had positive level of safety awareness and perceived positively on the preventive measures to reduce laboratory risk. Further, regardless of gender students enrolled in Physics 10 were more positively aware towards safety awareness than students enrolled in Physics 11. Similarly, a variation among the students perception towards safety awareness from the College of Engineering and Architecture (CEA and College of Industrial and Information Technology (CIIT occurred. Overall, present findings indicate a need to introduce laboratory safety awareness in Physics classes.
10. Creatine Synthesis: An Undergraduate Organic Chemistry Laboratory Experiment
Science.gov (United States)
Smith, Andri L.; Tan, Paula
2006-01-01
Students in introductory chemistry classes typically appreciate seeing the connection between course content and the "real world". For this reason, we have developed a synthesis of creatine monohydrate--a popular supplement used in sports requiring short bursts of energy--for introductory organic chemistry laboratory courses. Creatine monohydrate…
11. Blended Learning within an Undergraduate Exercise Physiology Laboratory
Science.gov (United States)
Elmer, Steven J.; Carter, Kathryn R.; Armga, Austin J.; Carter, Jason R.
2016-01-01
In physiological education, blended course formats (integration of face-to-face and online instruction) can facilitate increased student learning, performance, and satisfaction in classroom settings. There is limited evidence on the effectiveness of using blending course formats in laboratory settings. We evaluated the impact of blended learning…
12. A Green Enantioselective Aldol Condensation for the Undergraduate Organic Laboratory
Science.gov (United States)
Bennett, George D.
2006-01-01
A number of laboratory exercises for the organic chemistry curriculum that emphasize enantioselective synthesis of the aldol condensation which involves the proline-catalyzed condensation between acetone and isobutyraldehyde are explored. The experiment illustrates some of the trade-offs involved in green chemistry like the use of acetone in large…
13. Measurement of the sound absorption coefficient for an advanced undergraduate physics laboratory
Science.gov (United States)
2017-09-01
We present a simple experiment that allows advanced undergraduates to learn the basics of the acoustic properties of materials. The impedance tube-standing wave method is applied to study the normal absorption coefficient of acoustics insulators. The setup includes a tube, a speaker, a microphone, a digital function generator and an oscilloscope, material available in an undergraduate laboratory. Results of the change of the absorption coefficient with the frequency, the sample thickness and the sample density are analysed and compared with those obtained with a commercial system.
14. Using Capillary Electrophoresis to Determine the Purity of Acetylsalicylic Acid Synthesized in the Undergraduate Laboratory
Science.gov (United States)
Welder, Frank; Colyer, Christa L.
2001-11-01
Capillary electrophoresis (CE), although a powerful analytical tool, has found only limited application in undergraduate laboratory study. In an effort to expose freshman and sophomore chemistry students to this technique, thereby giving them practical instrumental experience early in their careers, we propose to use CE in the analysis of student-synthesized acetylsalicylic acid (ASA). The synthesis of ASA from salicylic acid (SA) is a routine undergraduate laboratory, although students rarely have the opportunity to test the purity of their product. The CE method described herein provides students with a method to test purity and yield of their product and to determine the effect of aging on their sample. CE can accomplish this in a short period of time, with minimal disruption to the regular laboratory curriculum. Optimized separation conditions, limits of detection, and linear range for ASA and SA are also given.
15. Introducing Mammalian Cell Culture and Cell Viability Techniques in the Undergraduate Biology Laboratory.
Science.gov (United States)
Bowey-Dellinger, Kristen; Dixon, Luke; Ackerman, Kristin; Vigueira, Cynthia; Suh, Yewseok K; Lyda, Todd; Sapp, Kelli; Grider, Michael; Crater, Dinene; Russell, Travis; Elias, Michael; Coffield, V McNeil; Segarra, Verónica A
2017-01-01
Undergraduate students learn about mammalian cell culture applications in introductory biology courses. However, laboratory modules are rarely designed to provide hands-on experience with mammalian cells or teach cell culture techniques, such as trypsinization and cell counting. Students are more likely to learn about cell culture using bacteria or yeast, as they are typically easier to grow, culture, and manipulate given the equipment, tools, and environment of most undergraduate biology laboratories. In contrast, the utilization of mammalian cells requires a dedicated biological safety cabinet and rigorous antiseptic techniques. For this reason, we have devised a laboratory module and method herein that familiarizes students with common cell culture procedures, without the use of a sterile hood or large cell culture facility. Students design and perform a time-efficient inquiry-based cell viability experiment using HeLa cells and tools that are readily available in an undergraduate biology laboratory. Students will become familiar with common techniques such as trypsinizing cells, cell counting with a hemocytometer, performing serial dilutions, and determining cell viability using trypan blue dye. Additionally, students will work with graphing software to analyze their data and think critically about the mechanism of death on a cellular level. Two different adaptations of this inquiry-based lab are presented-one for non-biology majors and one for biology majors. Overall, these laboratories aim to expose students to mammalian cell culture and basic techniques and help them to conceptualize their application in scientific research.
16. Transient Thermo-fluid Model of Meniscus Behavior and Slag Consumption in Steel Continuous Casting
Science.gov (United States)
Jonayat, A. S. M.; Thomas, Brian G.
2014-10-01
The behavior of the slag layer between the oscillating mold wall, the slag rim, the slag/liquid steel interface, and the solidifying steel shell, is of immense importance for the surface quality of continuous-cast steel. A computational model of the meniscus region has been developed, that includes transient heat transfer, multi-phase fluid flow, solidification of the slag, and movement of the mold during an oscillation cycle. First, the model is applied to a lab experiment done with a "mold simulator" to verify the transient temperature-field predictions. Next, the model is verified by matching with available literature and plant measurements of slag consumption. A reasonable agreement has been observed for both temperature and flow-field. The predictions show that transient temperature behavior depends on the location of the thermocouple during the oscillation relative to the meniscus. During an oscillation cycle, heat transfer variations in a laboratory frame of reference are more severe than experienced by the moving mold thermocouples, and the local heat transfer rate is increased greatly when steel overflows the meniscus. Finally, the model is applied to conduct a parametric study on the effect of casting speed, stroke, frequency, and modification ratio on slag consumption. Slag consumption per unit area increases with increase of stroke and modification ratio, and decreases with increase of casting speed while the relation with frequency is not straightforward. The match between model predictions and literature trends suggests that this methodology can be used for further investigations.
17. Accelerator-based techniques for the support of senior-level undergraduate physics laboratories
Science.gov (United States)
Williams, J. R.; Clark, J. C.; Isaacs-Smith, T.
2001-07-01
Approximately three years ago, Auburn University replaced its aging Dynamitron accelerator with a new 2MV tandem machine (Pelletron) manufactured by the National Electrostatics Corporation (NEC). This new machine is maintained and operated for the University by Physics Department personnel, and the accelerator supports a wide variety of materials modification/analysis studies. Computer software is available that allows the NEC Pelletron to be operated from a remote location, and an Internet link has been established between the Accelerator Laboratory and the Upper-Level Undergraduate Teaching Laboratory in the Physics Department. Additional software supplied by Canberra Industries has also been used to create a second Internet link that allows live-time data acquisition in the Teaching Laboratory. Our senior-level undergraduates and first-year graduate students perform a number of experiments related to radiation detection and measurement as well as several standard accelerator-based experiments that have been added recently. These laboratory exercises will be described, and the procedures used to establish the Internet links between our Teaching Laboratory and the Accelerator Laboratory will be discussed.
18. Accelerator-based techniques for the support of senior-level undergraduate physics laboratories
International Nuclear Information System (INIS)
Williams, J.R.; Clark, J.C.; Isaacs-Smith, T.
2001-01-01
Approximately three years ago, Auburn University replaced its aging Dynamitron accelerator with a new 2MV tandem machine (Pelletron) manufactured by the National Electrostatics Corporation (NEC). This new machine is maintained and operated for the University by Physics Department personnel, and the accelerator supports a wide variety of materials modification/analysis studies. Computer software is available that allows the NEC Pelletron to be operated from a remote location, and an Internet link has been established between the Accelerator Laboratory and the Upper-Level Undergraduate Teaching Laboratory in the Physics Department. Additional software supplied by Canberra Industries has also been used to create a second Internet link that allows live-time data acquisition in the Teaching Laboratory. Our senior-level undergraduates and first-year graduate students perform a number of experiments related to radiation detection and measurement as well as several standard accelerator-based experiments that have been added recently. These laboratory exercises will be described, and the procedures used to establish the Internet links between our Teaching Laboratory and the Accelerator Laboratory will be discussed
19. Structured Inquiry-Based Learning: Drosophila GAL4 Enhancer Trap Characterization in an Undergraduate Laboratory Course
OpenAIRE
Dunne, Christopher R.; Cillo, Anthony R.; Glick, Danielle R.; John, Katherine; Johnson, Cody; Kanwal, Jaspinder; Malik, Brian T.; Mammano, Kristina; Petrovic, Stefan; Pfister, William; Rascoe, Alexander S.; Schrom, Diane; Shapiro, Scott; Simkins, Jeffrey W.; Strauss, David
2014-01-01
We have developed and tested two linked but separable structured inquiry exercises using a set of Drosophila melanogaster GAL4 enhancer trap strains for an upper-level undergraduate laboratory methods course at Bucknell University. In the first, students learn to perform inverse PCR to identify the genomic location of the GAL4 insertion, using FlyBase to identify flanking sequences and the primary literature to synthesize current knowledge regarding the nearest gene. In the second, we cross e...
20. An undergraduate laboratory study of the polarisation of annihilation photons using Compton scattering
OpenAIRE
Knights, Patrick; Ryburn, Finlay; Tungate, Garry; Nikolopoulos, Konstantinos
2018-01-01
An experiment for the advanced undergraduate laboratory which allows students to study the effect of photon polarisation in Compton scattering and to explore q\\ uantum entanglement is described. The quantum entangled photons are produced through electron-positron annihilation in the $S$-state, and their polarisations a\\ re analysed using the Compton scattering cross-section dependence on the photon polarisation. The equipment necessary for this experiment is available at a typ\\ ical undergrad...
1. A Fast and Inexpensive Western Blot Experiment for the Undergraduate Laboratory
Science.gov (United States)
Farrell, Shawn O.; Farrell, Lynn E.
1995-08-01
Western blotting is an important, modern technique for transferring proteins from a gel onto nitrocellulose or other suitable support and then detecting a protein of interest using antibodies. We have developed an experiment and optimized the conditions for the undergraduate laboratory. The experiment can be done quickly using an electrophoretic blotter or more cheaply using passive transfer. This experiment allows the student to learn valuable procedures currently used in biochemistry and other biological sciences.
2. SOFTICE: Facilitating both Adoption of Linux Undergraduate Operating Systems Laboratories and Students' Immersion in Kernel Code
Directory of Open Access Journals (Sweden)
Alessio Gaspar
2007-06-01
Full Text Available This paper discusses how Linux clustering and virtual machine technologies can improve undergraduate students' hands-on experience in operating systems laboratories. Like similar projects, SOFTICE relies on User Mode Linux (UML to provide students with privileged access to a Linux system without creating security breaches on the hosting network. We extend such approaches in two aspects. First, we propose to facilitate adoption of Linux-based laboratories by using a load-balancing cluster made of recycled classroom PCs to remotely serve access to virtual machines. Secondly, we propose a new approach for students to interact with the kernel code.
3. Known structure, unknown function: An inquiry‐based undergraduate biochemistry laboratory course
Science.gov (United States)
Gray, Cynthia; Price, Carol W.; Lee, Christopher T.; Dewald, Alison H.; Cline, Matthew A.; McAnany, Charles E.
2015-01-01
Abstract Undergraduate biochemistry laboratory courses often do not provide students with an authentic research experience, particularly when the express purpose of the laboratory is purely instructional. However, an instructional laboratory course that is inquiry‐ and research‐based could simultaneously impart scientific knowledge and foster a student's research expertise and confidence. We have developed a year‐long undergraduate biochemistry laboratory curriculum wherein students determine, via experiment and computation, the function of a protein of known three‐dimensional structure. The first half of the course is inquiry‐based and modular in design; students learn general biochemical techniques while gaining preparation for research experiments in the second semester. Having learned standard biochemical methods in the first semester, students independently pursue their own (original) research projects in the second semester. This new curriculum has yielded an improvement in student performance and confidence as assessed by various metrics. To disseminate teaching resources to students and instructors alike, a freely accessible Biochemistry Laboratory Education resource is available at http://biochemlab.org. © 2015 The Authors Biochemistry and Molecular Biology Education published by Wiley Periodicals, Inc. on behalf of International Union of Biochemistry and Molecular Biology, 43(4):245–262, 2015. PMID:26148241
4. The development of Metacognition test in genetics laboratory for undergraduate students
Science.gov (United States)
A-nongwech, Nattapong; Pruekpramool, Chaninan
2018-01-01
The purpose of this research was to develop a Metacognition test in a Genetics Laboratory for undergraduate students. The participants were 30 undergraduate students of a Rajabhat university in Rattanakosin group in the second semester of the 2016 academic year using purposive sampling. The research instrument consisted of 1) Metacognition test and 2) a Metacognition test evaluation form for experts focused on three main points which were an accurate evaluation form of content, a consistency between Metacognition experiences and questions and the appropriateness of the test. The quality of the test was analyzed by using the Index of Consistency (IOC), discrimination and reliability. The results of developing Metacognition test were summarized as 1) The result of developing Metacognition test in a Genetics Laboratory for undergraduate students found that the Metacognition test contained 56 items of open - ended questions. The test composed of 1) four scientific situations, 2) fourteen items of open - ended questions in each scientific situation for evaluating components of Metacognition. The components of Metacognition consisted of Metacognitive knowledge, which were divided into person knowledge, task knowledge and strategy knowledge and Metacognitive experience, which were divided into planning, monitoring and evaluating, and 3) fourteen items of scoring criteria divided into four scales. 2) The results of the item analysis of Metacognition in Genetics Laboratory for undergraduate students found that Index of Consistency between Metacognitive experiences and questions were in the range between 0.75 - 1.00. An accuracy of content equaled 1.00. The appropriateness of the test equaled 1.00 in all situations and items. The discrimination of the test was in the range between 0.00 - 0.73. Furthermore, the reliability of the test equaled 0.97.
5. Transforming the Learning Environment of Undergraduate Physics Laboratories to Enhance Physics Inquiry Processes
Directory of Open Access Journals (Sweden)
Gregory P. Thomas
2017-04-01
Full Text Available Concerns persist regarding the lack of promotion of students’ scientific inquiry processes in undergraduate physics laboratories. The consensus in the literature is that, especially in the early years of undergraduate physics programs, students’ laboratory work is characterized by recipe type, step-by-step instructions for activities where the aim is often confirmation of an already well-established physics principle or concept. In response to evidence reflecting these concerns at their university, the authors successfully secured funding for this study. A mixed-method design was employed. In the 2011/2012 academic year baseline data were collected. A quantitative survey, the Undergraduate Physics Laboratory Learning Environment Scale (UPLLES was developed, validated, and used to explore students’ perceptions of their physics laboratory environments. Analysis of data from the UPLLES and from interviews confirmed the concerns evident in the literature and in a previous evaluation of laboratories undertaken in 2002. To address these concerns the activities that students were to perform in the laboratory section of the course/s were re/designed to engage students in more inquiry oriented thinking and activity. In Fall 2012, the newly developed laboratory activities and tutorials, were implemented for the first time in PHYS124; a first year course. These changes were accompanied by structured training of teaching assistants and changes to the structure of the evaluation of students’ laboratory performance. At the end of that term the UPLLES was administered (n = 266 and interviews with students conducted (n = 16 to explore their perceptions of their laboratory environments. Statistically significant differences (p<.001 between the students in the PHYS 124 classes of 2011/2012 and 2012/2013 across all dimensions were found. Effect sizes of 0.82 to 1.3, between the views of students in the first semester physics classes of 2011/2012 and 2012
6. Coupled thermo-fluid stress analysis of Kambara Reactor with various anchors in the stirring of molten iron at extremely high temperatures
International Nuclear Information System (INIS)
Huang, De-Shau; Huang, Feng-Chi
2014-01-01
Kambara Reactors (KR) are commonly used to reduce sulfur content in steel making, achieving efficiency levels exceeding 85% at 1300 °C. Unfortunately, the operational lifespan of the KR impeller is somewhat limited due to fracturing of the refractory material via thermal shock, resulting in the penetration of molten iron into the inner core. Few studies have investigated the coupled thermo-fluid stress of KR impellers at extremely high temperatures. This study employed CFX and FEM to simulate and analyze the molten iron and the resulting thermal stress imposed on the KR impeller. Simulation results including flow field, temperature, and thermal stress under extremely high temperatures are in strong agreement with empirical data. V-type anchors for the KR impeller outperformed Y-type anchors. - Highlights: • A thermo-fluid coupling approach is proposed to analyze the thermal stress. • The temperature and stress of the impeller are 790 °C and 744 MPa at the final stage. • The highest temperatures occur at the tip of anchors, which causes material crack. • The thermal stress in impellers with Y-type anchors is greater than V-type anchors
7. Identification of Forensic Samples via Mitochondrial DNA in the Undergraduate Biochemistry Laboratory
Science.gov (United States)
Millard, Julie T.; Pilon, André M.
2003-04-01
A recent forensic approach for identification of unknown biological samples is mitochondrial DNA (mtDNA) sequencing. We describe a laboratory exercise suitable for an undergraduate biochemistry course in which the polymerase chain reaction is used to amplify a 440 base pair hypervariable region of human mtDNA from a variety of "crime scene" samples (e.g., teeth, hair, nails, cigarettes, envelope flaps, toothbrushes, and chewing gum). Amplification is verified via agarose gel electrophoresis and then samples are subjected to cycle sequencing. Sequence alignments are made via the program CLUSTAL W, allowing students to compare samples and solve the "crime."
8. A new method of measuring gravitational acceleration in an undergraduate laboratory program
Science.gov (United States)
Wang, Qiaochu; Wang, Chang; Xiao, Yunhuan; Schulte, Jurgen; Shi, Qingfan
2018-01-01
This paper presents a high accuracy method to measure gravitational acceleration in an undergraduate laboratory program. The experiment is based on water in a cylindrical vessel rotating about its vertical axis at a constant speed. The water surface forms a paraboloid whose focal length is related to rotational period and gravitational acceleration. This experimental setup avoids classical source errors in determining the local value of gravitational acceleration, so prevalent in the common simple pendulum and inclined plane experiments. The presented method combines multiple physics concepts such as kinematics, classical mechanics and geometric optics, offering the opportunity for lateral as well as project-based learning.
9. Undergraduate Laboratory Experiment: Measuring Matter Antimatter Asymmetries at the Large Hadron Collider
CERN Document Server
Parkes, Chris; Gutierrez, J
2015-01-01
This document is the student manual for a third year undergraduate laboratory experiment at the University of Manchester. This project aims to measure a fundamental difference between the behaviour of matter and antimatter through the analysis of data collected by the LHCb experiment at the Large Hadron Collider. The three-body dmecays $B^\\pm \\rightarrow h^\\pm h^+ h^-$, where $h^\\pm$ is a $\\pi^\\pm$ or $K^\\pm$ are studied. The inclusive matter antimatter asymmetry is calculated, and larger asymmetries are searched for in localized regions of the phase-space.
10. Better understanding of homologous recombination through a 12-week laboratory course for undergraduates majoring in biotechnology.
Science.gov (United States)
Li, Ming; Shen, Xiaodong; Zhao, Yan; Hu, Xiaomei; Hu, Fuquan; Rao, Xiancai
2017-07-08
Homologous recombination, a central concept in biology, is defined as the exchange of DNA strands between two similar or identical nucleotide sequences. Unfortunately, undergraduate students majoring in biotechnology often experience difficulties in understanding the molecular basis of homologous recombination. In this study, we developed and implemented a 12-week laboratory course for biotechnology undergraduates in which gene targeting in Streptococcus suis was used to facilitate their understanding of the basic concept and process of homologous recombination. Students worked in teams of two to select a gene of interest to create a knockout mutant using methods that relied on homologous recombination. By integrating abstract knowledge and practice in the process of scientific research, students gained hands-on experience in molecular biology techniques while learning about the principle and process of homologous recombination. The learning outcomes and survey-based assessment demonstrated that students substantially enhanced their understanding of how homologous recombination could be used to study gene function. Overall, the course was very effective for helping biotechnology undergraduates learn the theory and application of homologous recombination, while also yielding positive effects in developing confidence and scientific skills for future work in research. © 2017 by The International Union of Biochemistry and Molecular Biology, 45(4):329-335, 2017. © 2017 The International Union of Biochemistry and Molecular Biology.
11. Development, Evaluation and Use of a Student Experience Survey in Undergraduate Science Laboratories: The Advancing Science by Enhancing Learning in the Laboratory Student Laboratory Learning Experience Survey
Science.gov (United States)
Barrie, Simon C.; Bucat, Robert B.; Buntine, Mark A.; Burke da Silva, Karen; Crisp, Geoffrey T.; George, Adrian V.; Jamie, Ian M.; Kable, Scott H.; Lim, Kieran F.; Pyke, Simon M.; Read, Justin R.; Sharma, Manjula D.; Yeung, Alexandra
2015-07-01
Student experience surveys have become increasingly popular to probe various aspects of processes and outcomes in higher education, such as measuring student perceptions of the learning environment and identifying aspects that could be improved. This paper reports on a particular survey for evaluating individual experiments that has been developed over some 15 years as part of a large national Australian study pertaining to the area of undergraduate laboratories-Advancing Science by Enhancing Learning in the Laboratory. This paper reports on the development of the survey instrument and the evaluation of the survey using student responses to experiments from different institutions in Australia, New Zealand and the USA. A total of 3153 student responses have been analysed using factor analysis. Three factors, motivation, assessment and resources, have been identified as contributing to improved student attitudes to laboratory activities. A central focus of the survey is to provide feedback to practitioners to iteratively improve experiments. Implications for practitioners and researchers are also discussed.
12. Validating the collision-dominated Child-Langmuir law for a dc discharge cathode sheath in an undergraduate laboratory
International Nuclear Information System (INIS)
Lisovskiy, V; Yegorenkov, V
2009-01-01
In this paper, we propose a simple method of observing the collision-dominated Child-Langmuir law in the course of an undergraduate laboratory work devoted to studying the properties of gas discharges. To this end we employ the dc gas discharge whose properties are studied in sufficient detail. The undergraduate laboratory work itself is reduced to registering the voltage drop across the electrodes, the discharge current as well as the cathode sheath thickness. We can easily perform the measurements of all three quantities with sufficient accuracy in a laboratory equipped with vacuum pumps.
13. Microwave-Enhanced Organic Syntheses for the Undergraduate Laboratory: Diels-Alder Cycloaddition, Wittig Reaction, and Williamson Ether Synthesis
Science.gov (United States)
Baar, Marsha R.; Falcone, Danielle; Gordon, Christopher
2010-01-01
Microwave heating enhanced the rate of three reactions typically performed in our undergraduate organic chemistry laboratory: a Diels-Alder cycloaddition, a Wittig salt formation, and a Williamson ether synthesis. Ninety-minute refluxes were shortened to 10 min using a laboratory-grade microwave oven. In addition, yields improved for the Wittig…
14. "Anisakis Simplex" Infection in Mackerel: A Reliable Laboratory Exercise to Demonstrate Important Principles in Parasitology to Undergraduates
Science.gov (United States)
Coombs, I.; Tatner, M.; Paterson, V.
2013-01-01
Practical laboratory work in parasitology can be very limited, due to the difficulty in maintaining multi-host parasite life cycles, especially for a large, once-yearly undergraduate laboratory class for life science students. The use of mackerel, "Scomber scombrus," bought from a local fishmonger, is an ideal model to investigate important…
15. The ATLAS project: The effects of a constructionist digital laboratory project on undergraduate laboratory performance.
Science.gov (United States)
Shoepe, Todd C; Cavedon, Dana K; Derian, Joseph M; Levy, Celine S; Morales, Amy
2015-01-01
Anatomical education is a dynamic field where developments in the implementation of constructive, situated-learning show promise in improving student achievement. The purpose of this study was to examine the effectiveness of an individualized, technology heavy project in promoting student performance in a combined anatomy and physiology laboratory course. Mixed-methods research was used to compare two cohorts of anatomy laboratories separated by the adoption of a new laboratory atlas project, which were defined as preceding (PRE) and following the adoption of the Anatomical Teaching and Learning Assessment Study (ATLAS; POST). The ATLAS project required the creation of a student-generated, photographic atlas via acquisition of specimen images taken with tablet technology and digital microscope cameras throughout the semester. Images were transferred to laptops, digitally labeled and photo edited weekly, and compiled into a digital book using Internet publishing freeware for final project submission. An analysis of covariance confirmed that student final examination scores were improved (P project (PRE, n = 75; POST, n = 90; means ± SE; 74.9 ± 0.9 versus 78.1 ± 0.8, respectively) after controlling for cumulative student grade point average. Analysis of questionnaires collected (n = 68) from the post group suggested students identified with atlas objectives, appreciated the comprehensive value in final examination preparation, and the constructionism involved, but recommended alterations in assignment logistics and the format of the final version. Constructionist, comprehensive term-projects utilizing student-preferred technologies could be used to improve performance toward student learning outcomes. © 2014 American Association of Anatomists.
16. Integrating bio-inorganic and analytical chemistry into an undergraduate biochemistry laboratory.
Science.gov (United States)
Erasmus, Daniel J; Brewer, Sharon E; Cinel, Bruno
2015-01-01
Undergraduate laboratories expose students to a wide variety of topics and techniques in a limited amount of time. This can be a challenge and lead to less exposure to concepts and activities in bio-inorganic chemistry and analytical chemistry that are closely-related to biochemistry. To address this, we incorporated a new iron determination by atomic absorption spectroscopy exercise as part of a five-week long laboratory-based project on the purification of myoglobin from beef. Students were required to prepare samples for chemical analysis, operate an atomic absorption spectrophotometer, critically evaluate their iron data, and integrate these data into a study of myoglobin. © 2015 The International Union of Biochemistry and Molecular Biology.
17. Observing Chemotaxis in Vibrio fischeri Using Soft Agar Assays in an Undergraduate Microbiology Laboratory
Directory of Open Access Journals (Sweden)
Cindy R. DeLoney-Marino
2013-08-01
Full Text Available Chemotaxis, the directed movement of cells towards or away from a chemical, is both an exciting and complicated behavior observed in many bacterial species. Attempting to adequately visualize or demonstrate the chemotaxic response of bacteria in the classroom is difficult at best, with good models to illustrate the concept lacking. The BSL-1 marine bacterium Vibrio fischeri (a.k.a. Aliivibrio fischeri is easy to culture, making it an ideal candidate for experiments in an undergraduate microbiology course. A number of chemoattractants for V. fischeri have been identified, including a variety of sugars, nucleosides, and amino acids (1, 2. Below presents how the soft agar-based chemotaxis assay can be implemented in the undergraduate laboratory. As bacterial cells migrate towards one or more attractants in soft agar, students can directly observe the chemotaxic behavior of V. fischeri without the need to learn complicated techniques or use specialized equipment. Once the bands of bacterial cells are observed, the migration can then be disrupted by the addition of excess attractant to the soft agar, thereby visualizing what happens once cells are no longer in a gradient of attractant. In addition, soft agar plates lacking attractants can be used to visualize the random movements of bacterial cells that are non-chemotaxing. These exercises can be used in the microbiology laboratory to help students understand the complex behavior of bacterial chemotaxis.
18. Influence of study approaches and course design on academic success in the undergraduate anatomy laboratory.
Science.gov (United States)
Eleazer, Courtney D; Scopa Kelso, Rebecca
2018-01-04
19. Advancing Space Sciences through Undergraduate Research Experiences at UC Berkeley's Space Sciences Laboratory - a novel approach to undergraduate internships for first generation community college students
Science.gov (United States)
Raftery, C. L.; Davis, H. B.; Peticolas, L. M.; Paglierani, R.
2015-12-01
The Space Sciences Laboratory at UC Berkeley launched an NSF-funded Research Experience for Undergraduates (REU) program in the summer of 2015. The "Advancing Space Sciences through Undergraduate Research Experiences" (ASSURE) program recruited heavily from local community colleges and universities, and provided a multi-tiered mentorship program for students in the fields of space science and engineering. The program was focussed on providing a supportive environment for 2nd and 3rd year undergraduates, many of whom were first generation and underrepresented students. This model provides three levels of mentorship support for the participating interns: 1) the primary research advisor provides academic and professional support. 2) The program coordinator, who meets with the interns multiple times per week, provides personal support and helps the interns to assimilate into the highly competitive environment of the research laboratory. 3) Returning undergraduate interns provided peer support and guidance to the new cohort of students. The impacts of this program on the first generation students and the research mentors, as well as the lessons learned will be discussed.
20. Laboratory Techniques in Geology: Embedding Analytical Methods into the Undergraduate Curriculum
Science.gov (United States)
Baedke, S. J.; Johnson, E. A.; Kearns, L. E.; Mazza, S. E.; Gazel, E.
2014-12-01
Paid summer REU experiences successfully engage undergraduate students in research and encourage them to continue to graduate school and scientific careers. However these programs only accommodate a limited number of students due to funding constraints, faculty time commitments, and limited access to needed instrumentation. At JMU, the Department of Geology and Environmental Science has embedded undergraduate research into the curriculum. Each student fulfilling a BS in Geology or a BA in Earth Science completes 3 credits of research, including a 1-credit course on scientific communication, 2 credits of research or internship, followed by a presentation of that research. Our department has successfully acquired many analytical instruments and now has an XRD, SEM/EDS, FTIR, handheld Raman, AA, ion chromatograph, and an IRMS. To give as many students as possible an overview to the scientific uses and operation methods for these instruments, we revived a laboratory methods course that includes theory and practical use of instrumentation at JMU, plus XRF sample preparation and analysis training at Virginia Tech during a 1-day field trip. In addition to practical training, projects included analytical concepts such as evaluating analytical vs. natural uncertainty, determining error on multiple measurements, signal-to-noise ratio, and evaluating data quality. State funding through the 4-VA program helped pay for analytical supplies and support for students to complete research projects over the summer or during the next academic year using instrumentation from the course. This course exemplifies an alternative path to broadening participation in undergraduate research and creating stronger partnerships between PUI's and research universities.
1. Numerical Study of Thermo-Fluid Features of Electrically Conducting Fluids in Tube Bank Heat Exchangers Exposed to Uniform Magnetic Fields
Energy Technology Data Exchange (ETDEWEB)
Oh, Jin Ho; Kang, Namcheol [Kyungpook Nat’l Univ., Daegu (Korea, Republic of)
2017-10-15
When an electrically conducting fluid flows through a staggered tube bank, the heat transfer and fluid flow features are changed by the externally introduced magnetic field. This study provides a numerical investigation of this phenomenon. Heat and fluid flows are investigated for unsteady laminar flows at Reynolds numbers of 50 and 100 with the Hartmann number gradually increasing from zero to 100. As the Hartmann number increases, and owing to the effects of the introduced magnetic field, the velocity boundary layer near the tube wall is thinned, the flow separation is delayed downstream, and the shrinkage of a recirculation zone formed near the rear side is observed. Based on these thermo-fluid deformations, the resulting changes in the local and average Nusselt number are investigated.
2. Improving Online Interactions: Lessons from an Online Anatomy Course with a Laboratory for Undergraduate Students.
Science.gov (United States)
Attardi, Stefanie M; Barbeau, Michele L; Rogers, Kem A
2018-03-01
3. Measuring the spatial resolution of an optical system in an undergraduate optics laboratory
Science.gov (United States)
Leung, Calvin; Donnelly, T. D.
2017-06-01
Two methods of quantifying the spatial resolution of a camera are described, performed, and compared, with the objective of designing an imaging-system experiment for students in an undergraduate optics laboratory. With the goal of characterizing the resolution of a typical digital single-lens reflex (DSLR) camera, we motivate, introduce, and show agreement between traditional test-target contrast measurements and the technique of using Fourier analysis to obtain the modulation transfer function (MTF). The advantages and drawbacks of each method are compared. Finally, we explore the rich optical physics at work in the camera system by calculating the MTF as a function of wavelength and f-number. For example, we find that the Canon 40D demonstrates better spatial resolution at short wavelengths, in accordance with scalar diffraction theory, but is not diffraction-limited, being significantly affected by spherical aberration. The experiment and data analysis routines described here can be built and written in an undergraduate optics lab setting.
4. Design and construction of a two-temperature preference behavioral assay for undergraduate neuroscience laboratories.
Science.gov (United States)
Daniels, Richard L; McKemy, David D
2010-01-01
Behavioral assays in the undergraduate neuroscience laboratory are useful for illustrating a variety of physiological concepts. An example is homeostatic temperature regulation (thermoregulation). Many model organisms, from flies to mice, regulate internal temperatures in part by moving to suitable climates (thermotaxis). A particularly reliable method of quantifying temperature-dependent thermotactic behaviors is the two-temperature preference behavioral assay. In this preparation, an organism is free to move between two temperature-controlled surfaces, thus revealing its preferred thermal environment. Here we present the design and construction of a two-temperature preference assay chamber. The device uses Peltier-based thermoelectric modules (TECs) for heating and cooling, and is capable of precision control of temperatures from -5ºC to 60ºC. Our approach can be easily adapted for use in a variety of physiological and behavioral assays that require precise temperature control over a wide range of temperatures.
5. One-dimensional light localization with classical scatterers: An advanced undergraduate laboratory experiment
Science.gov (United States)
Kemp, K. J.; Barker, S.; Guthrie, J.; Hagood, B.; Havey, M. D.
2016-10-01
The phenomenon of electronic wave localization through disorder remains an important area of fundamental and applied research. Localization of all wave phenomena, including light, is thought to exist in a restricted one-dimensional geometry. We present here a series of experiments to illustrate, using a straightforward experimental arrangement and approach, the localization of light in a quasi-one-dimensional physical system. In the experiments, reflected and transmitted light from a stack of glass slides of varying thickness reveals an Ohm's law type behavior for small thicknesses, and evolution to exponential decay of the transmitted power for larger thicknesses. For larger stacks of slides, a weak departure from one-dimensional behavior is also observed. The experiment and analysis of the results, showing many of the essential features of wave localization, is relatively straightforward, economical, and suitable for laboratory experiments at an undergraduate level.
6. Cross-disciplinary thermoregulation and sweat analysis laboratory experiences for undergraduate Chemistry and Exercise Science students.
Science.gov (United States)
Mulligan, Gregory; Taylor, Nichole; Glen, Mary; Tomlin, Dona; Gaul, Catherine A
2011-06-01
Cross-disciplinary (CD) learning experiences benefit student understanding of concepts and curriculum by offering opportunities to explore topics from the perspectives of alternate fields of study. This report involves a qualitative evaluation of CD health sciences undergraduate laboratory experiences in which concepts and students from two distinct disciplines [chemistry (CHEM) and exercise physiology (EPHE)] combined to study exercise thermoregulation and sweat analysis. Twenty-eight senior BSc Kinesiology (EPHE) students and 42 senior BSc CHEM students participated as part of their mutually exclusive, respective courses. The effectiveness of this laboratory environment was evaluated qualitatively using written comments collected from all students as well as from formal focus groups conducted after the CD laboratory with a representative cohort from each class (n = 16 CHEM students and 9 EPHE students). An open coding strategy was used to analyze the data from written feedback and focus group transcripts. Coding topics were generated and used to develop five themes found to be consistent for both groups of students. These themes reflected the common student perceptions that the CD experience was valuable and that students enjoyed being able to apply academic concepts to practical situations as well as the opportunity to interact with students from another discipline of study. However, students also reported some challenges throughout this experience that stemmed from the combination of laboratory groups from different disciplines with limited modification to the design of the original, pre-CD, learning environments. The results indicate that this laboratory created an effective learning opportunity that fostered student interest and enthusiasm for learning. The findings also provide information that could inform subsequent design and implementation of similar CD experiences to enhance engagement of all students and improve instructor efficacy.
7. Biotechnology by Design: An Introductory Level, Project-Based, Synthetic Biology Laboratory Program for Undergraduate Students
Directory of Open Access Journals (Sweden)
Dale L. Beach
2015-08-01
Full Text Available Synthetic biology offers an ideal opportunity to promote undergraduate laboratory courses with research-style projects, immersing students in an inquiry-based program that enhances the experience of the scientific process. We designed a semester-long, project-based laboratory curriculum using synthetic biology principles to develop a novel sensory device. Students develop subject matter knowledge of molecular genetics and practical skills relevant to molecular biology, recombinant DNA techniques, and information literacy. During the spring semesters of 2014 and 2015, the Synthetic Biology Laboratory Project was delivered to sophomore genetics courses. Using a cloning strategy based on standardized BioBrick genetic “parts,” students construct a “reporter plasmid” expressing a reporter gene (GFP controlled by a hybrid promoter regulated by the lac-repressor protein (lacI. In combination with a “sensor plasmid,” the production of the reporter phenotype is inhibited in the presence of a target environmental agent, arabinose. When arabinose is absent, constitutive GFP expression makes cells glow green. But the presence of arabinose activates a second promoter (pBAD to produce a lac-repressor protein that will inhibit GFP production. Student learning was assessed relative to five learning objectives, using a student survey administered at the beginning (pre-survey and end (post-survey of the course, and an additional 15 open-ended questions from five graded Progress Report assignments collected throughout the course. Students demonstrated significant learning gains (p < 0.05 for all learning outcomes. Ninety percent of students indicated that the Synthetic Biology Laboratory Project enhanced their understanding of molecular genetics. The laboratory project is highly adaptable for both introductory and advanced courses. Editor's Note:The ASM advocates that students must successfully demonstrate the ability to explain and practice safe
8. Does the Pedagogy for the Teaching of First Year Undergraduate Laboratory Practicals Still Meet the Needs of the Curriculum?
Directory of Open Access Journals (Sweden)
Ann Hopper
2014-06-01
Full Text Available This work examines the teaching approach for chemistry laboratory practicals for first year undergraduate students to determine if the underpinning pedagogical strategy meets the requirements for these students for the remainder of their undergraduate programme. This is based on the knowledge, skills, content and learning outcomes for undergraduate chemistry courses. This work aims to enhance the first year experience of chemistry education by facilitating greater student engagement and “deeper” learning of relevant content during practical laboratory experiences by focusing on the learners’ needs. During this research, a survey of undergraduate science students from 2nd, 3rd and 4th years was carried out to determine if first year chemistry practicals facilitated the development of skills needed in further science education. It concluded that overall there was a positive response to first year laboratory practicals, that students engaged with them and felt they assisted with skills required for subsequent years of undergraduate study. Participants were most satisfied with the organic chemistry experiments while, for the physical/analytical chemistry experiments, the results obtained reiterated difficulties with mathematical calculations that are accepted as an issue in other aspects of third level STEM (Science, Technology, Engineering and Mathematics subjects. As a result of these findings, modifications that were made to the laboratory practical element included a pre-populated workbook supplied to the students and the introduction of pre-laboratory questions to be completed by each student before each session to reduce cognitive load and improve the students’ knowledge and understanding of 2 the purpose and potential outcomes of each laboratory practical. Also, the total first year chemistry syllabus was re-organised, as was the scheduling of the experiments to synchronise the theory lectures with the experiments as far as was
9. Fitting It All In: Adapting a Green Chemistry Extraction Experiment for Inclusion in an Undergraduate Analytical Laboratory
Science.gov (United States)
Buckley, Heather L.; Beck, Annelise R.; Mulvihill, Martin J.; Douskey, Michelle C.
2013-01-01
Several principles of green chemistry are introduced through this experiment designed for use in the undergraduate analytical chemistry laboratory. An established experiment of liquid CO2 extraction of D-limonene has been adapted to include a quantitative analysis by gas chromatography. This facilitates drop-in incorporation of an exciting…
10. Ab Initio Determinations of Photoelectron Spectra Including Vibronic Features: An Upper-Level Undergraduate Physical Chemistry Laboratory
Science.gov (United States)
Lord, Richard L.; Davis, Lisa; Millam, Evan L.; Brown, Eric; Offerman, Chad; Wray, Paul; Green, Susan M. E.
2008-01-01
We present a first-principles determination of the photoelectron spectra of water and hypochlorous acid as a laboratory exercise accessible to students in an undergraduate physical chemistry course. This paper demonstrates the robustness and user-friendliness of software developed for the Franck-Condon factor calculation. While the calculator is…
11. Preparation of (+)-α-terpineol from (+)-limonene: monoterpenes with pleasant odor in a project for undergraduate organic chemistry laboratory
International Nuclear Information System (INIS)
Baptistella, Lucia Helena Brito; Imamura, Paulo Mitsuo; Melo, Leandro Vilela de; Castello, Claudio
2009-01-01
A synthesis of (+)-α-terpineol from (+)-limonene was proposed as a project for undergraduate organic laboratory course. Terpineol is a useful flavor and fragrance compound, and several aspects of this preparation are suited for experimental organic classes, including basic techniques for extraction and analyses of essential oils, different reaction types and the possibility of a high degree of student interest. (author)
12. Red Seaweed Enzyme-Catalyzed Bromination of Bromophenol Red: An Inquiry-Based Kinetics Laboratory Experiment for Undergraduates
Science.gov (United States)
Jittam, Piyachat; Boonsiri, Patcharee; Promptmas, Chamras; Sriwattanarothai, Namkang; Archavarungson, Nattinee; Ruenwongsa, Pintip; Panijpan, Bhinyo
2009-01-01
Haloperoxidase enzymes are of interest for basic and applied bioscientists because of their increasing importance in pharmaceutical industry and environmental cleanups. In a guided inquiry-based laboratory experiment for life-science, agricultural science, and health science undergraduates, the bromoperoxidase from a red seaweed was used to…
13. Nickel-Catalyzed Suzuki-Miyaura Cross-Coupling in a Green Alcohol Solvent for an Undergraduate Organic Chemistry Laboratory
Science.gov (United States)
Hie, Liana; Chang, Jonah J.; Garg, Neil K.
2015-01-01
A modern undergraduate organic chemistry laboratory experiment involving the Suzuki-Miyaura coupling is reported. Although Suzuki-Miyaura couplings typically employ palladium catalysts in environmentally harmful solvents, this experiment features the use of inexpensive nickel catalysis, in addition to a "green" alcohol solvent. The…
14. The Cyclohexanol Cycle and Synthesis of Nylon 6,6: Green Chemistry in the Undergraduate Organic Laboratory
Science.gov (United States)
Dintzner, Matthew R.; Kinzie, Charles R.; Pulkrabek, Kimberly; Arena, Anthony F.
2012-01-01
A one-term synthesis project that incorporates many of the principles of green chemistry is presented for the undergraduate organic laboratory. In this multistep scheme of reactions, students react, recycle, and ultimately convert cyclohexanol to nylon 6,6. The individual reactions in the project employ environmentally friendly methodologies, and…
15. Oxidation of Borneol to Camphor Using Oxone and Catalytic Sodium Chloride: A Green Experiment for the Undergraduate Organic Chemistry Laboratory
Science.gov (United States)
Lang, Patrick T.; Harned, Andrew M.; Wissinger, Jane E.
2011-01-01
A new green oxidation procedure was developed for the undergraduate organic teaching laboratories using Oxone and a catalytic quantity of sodium chloride for the conversion of borneol to camphor. This simple 1 h, room temperature reaction afforded high quality and yield of product, was environmentally friendly, and produced negligible quantities…
16. HPLC of the Polypeptides in a Hydrolyzate of Egg-White Lysozyme. An Experiment for the Undergraduate Biochemistry Laboratory.
Science.gov (United States)
Richardson, W. S., III; Burns, L.
1988-01-01
Describes a simple high-performance liquid chromatography experiment for undergraduate biochemistry laboratories. The experiment illustrates the separation of polypeptides by a step gradient elution using a single pump instrument with no gradient attachments. Discusses instrumentation, analysis, a sample preparation, and results. (CW)
17. Controlled Synthesis of Nanomaterials at the Undergraduate Laboratory: Cu(OH)[subscript 2] and CuO Nanowires
Science.gov (United States)
da Silva, Anderson G. M.; Rodrigues, Thenner S.; Parussulo, Andre´ L. A.; Candido, Eduardo G.; Geonmonond, Rafael S.; Brito, Hermi F.; Toma, Henrique E.; Camargo, Pedro H. C.
2017-01-01
Undergraduate-level laboratory experiments that involve the synthesis of nanomaterials with well-defined/controlled shapes are very attractive under the umbrella of nanotechnology education. Herein we describe a low-cost and facile experiment for the synthesis of Cu(OH)[subscript 2] and CuO nanowires comprising three main parts: (i) synthesis of…
18. Enhancing Hispanic Minority Undergraduates' Botany Laboratory Experiences: Implementation of an Inquiry-Based Plant Tissue Culture Module Exercise
Science.gov (United States)
Siritunga, Dimuth; Navas, Vivian; Diffoot, Nanette
2012-01-01
Early involvement of students in hands-on research experiences are known to demystify research and promote the pursuit of careers in science. But in large enrollment departments such opportunities for undergraduates to participate in research are rare. To counteract such lack of opportunities, inquiry-based laboratory module in plant tissue…
19. Acid-Catalyzed Preparation of Biodiesel from Waste Vegetable Oil: An Experiment for the Undergraduate Organic Chemistry Laboratory
Science.gov (United States)
Bladt, Don; Murray, Steve; Gitch, Brittany; Trout, Haylee; Liberko, Charles
2011-01-01
This undergraduate organic laboratory exercise involves the sulfuric acid-catalyzed conversion of waste vegetable oil into biodiesel. The acid-catalyzed method, although inherently slower than the base-catalyzed methods, does not suffer from the loss of product or the creation of emulsion producing soap that plagues the base-catalyzed methods when…
20. Assembly of a Modular Fluorimeter and Associated Software: Using LabVIEW in an Advanced Undergraduate Analytical Chemistry Laboratory
Science.gov (United States)
Algar, W. Russ; Massey, Melissa; Krull, Ulrich J.
2009-01-01
A laboratory activity for an upper-level undergraduate course in instrumental analysis has been created around LabVIEW. Students learn rudimentary programming and interfacing skills during the construction of a fluorimeter assembled from common modular components. The fluorimeter consists of an inexpensive data acquisition module, LED light…
1. Synthesis of 10-Ethyl Flavin: A Multistep Synthesis Organic Chemistry Laboratory Experiment for Upper-Division Undergraduate Students
Science.gov (United States)
Sichula, Vincent A.
2015-01-01
A multistep synthesis of 10-ethyl flavin was developed as an organic chemistry laboratory experiment for upper-division undergraduate students. Students synthesize 10-ethyl flavin as a bright yellow solid via a five-step sequence. The experiment introduces students to various hands-on experimental organic synthetic techniques, such as column…
2. Oxorhenium Complexes for Catalytic Hydrosilylation and Hydrolytic Hydrogen Production: A Multiweek Advanced Laboratory Experiment for Undergraduate Students
Science.gov (United States)
Ison, A.; Ison, E. A.; Perry, C. M.
2017-01-01
An effective way of teaching undergraduates a full complement of research skills is through a multiweek advanced laboratory experiment. Here we outline a comprehensive set of experiments adapted from current primary literature focusing on organic and inorganic synthesis, catalysis, reactivity, and reaction kinetics. The catalyst,…
3. Nickel-Catalyzed Suzuki–Miyaura Cross-Coupling in a Green Alcohol Solvent for an Undergraduate Organic Chemistry Laboratory
OpenAIRE
Hie, Liana; Chang, Jonah J.; Garg, Neil K.
2014-01-01
A modern undergraduate organic chemistry laboratory experiment involving the Suzuki–Miyaura coupling is reported. Although Suzuki–Miyaura couplings typically employ palladium catalysts in environmentally harmful solvents, this experiment features the use of inexpensive nickel catalysis, in addition to a “green” alcohol solvent. The experiment employs heterocyclic substrates, which are important pharmaceutical building blocks. Thus, this laboratory procedure exposes students to a variety of co...
4. Chiral Compounds and Green Chemistry in Undergraduate Organic Laboratories: Reduction of a Ketone by Sodium Borohydride and Baker's Yeast
Science.gov (United States)
Pohl, Nicola; Clague, Allen; Schwarz, Kimberly
2002-06-01
We describe an integrated set of experiments for the undergraduate organic laboratory that allows students to compare and contrast biological and chemical means of introducing chirality into a molecule. The racemic reduction of ethyl acetoacetate with sodium borohydride and the same reduction in the presence of a tartaric acid ligand are described, and a capillary gas chromatography column packed with a chiral material for product analysis is introduced. The results of these two hydride reactions are compared with the results of a common undergraduate experiment, the baker's yeast reduction of ethyl acetoacetate.
5. Nickel-Catalyzed Suzuki-Miyaura Cross-Coupling in a Green Alcohol Solvent for an Undergraduate Organic Chemistry Laboratory.
Science.gov (United States)
Hie, Liana; Chang, Jonah J; Garg, Neil K
2015-03-10
A modern undergraduate organic chemistry laboratory experiment involving the Suzuki-Miyaura coupling is reported. Although Suzuki-Miyaura couplings typically employ palladium catalysts in environmentally harmful solvents, this experiment features the use of inexpensive nickel catalysis, in addition to a "green" alcohol solvent. The experiment employs heterocyclic substrates, which are important pharmaceutical building blocks. Thus, this laboratory procedure exposes students to a variety of contemporary topics in organic chemistry, including transition metal-catalyzed cross-couplings, green chemistry, and the importance of heterocycles in drug discovery, none of which are well represented in typical undergraduate organic chemistry curricula. The experimental protocol uses commercially available reagents and is useful in both organic and inorganic instructional laboratories.
6. [A Perspective on Innovation for Efficient Medical Practice in View of Undergraduate and Postgraduate Education and Training in Laboratory Medicine].
Science.gov (United States)
2015-10-01
Continuous advances in medical laboratory technology have driven major changes in the practice of laboratory medicine over the past two decades. The importance of the overall quality of a medical laboratory has been ever-increasing in order to improve and ensure the quality and safety of clinical practice by physicians in any type of medical facility. Laboratory physicians and professional staff should challenge themselves more than ever in various ways to cooperate and contribute with practicing physicians for the appropriate utilization of laboratory testing. This will certainly lead to a decrease in inappropriate or unnecessary laboratory testing, resulting in reducing medical costs. In addition, not only postgraduate, but also undergraduate medical education/training systems must be markedly innovated, considering recent rapid progress in electronic information and communication technologies.
7. Developing a new experimental system for an undergraduate laboratory exercise to teach theories of visuomotor learning.
Science.gov (United States)
Kasuga, Shoko; Ushiba, Junichi
2014-01-01
Humans have a flexible motor ability to adapt their movements to changes in the internal/external environment. For example, using arm-reaching tasks, a number of studies experimentally showed that participants adapt to a novel visuomotor environment. These results helped develop computational models of motor learning implemented in the central nervous system. Despite the importance of such experimental paradigms for exploring the mechanisms of motor learning, because of the cost and preparation time, most students are unable to participate in such experiments. Therefore, in the current study, to help students better understand motor learning theories, we developed a simple finger-reaching experimental system using commonly used laptop PC components with an open-source programming language (Processing Motor Learning Toolkit: PMLT). We found that compared to a commercially available robotic arm-reaching device, our PMLT accomplished similar learning goals (difference in the error reduction between the devices, P = 0.10). In addition, consistent with previous reports from visuomotor learning studies, the participants showed after-effects indicating an adaptation of the motor learning system. The results suggest that PMLT can serve as a new experimental system for an undergraduate laboratory exercise of motor learning theories with minimal time and cost for instructors.
8. Structured inquiry-based learning: Drosophila GAL4 enhancer trap characterization in an undergraduate laboratory course.
Directory of Open Access Journals (Sweden)
Christopher R Dunne
2014-12-01
Full Text Available We have developed and tested two linked but separable structured inquiry exercises using a set of Drosophila melanogaster GAL4 enhancer trap strains for an upper-level undergraduate laboratory methods course at Bucknell University. In the first, students learn to perform inverse PCR to identify the genomic location of the GAL4 insertion, using FlyBase to identify flanking sequences and the primary literature to synthesize current knowledge regarding the nearest gene. In the second, we cross each GAL4 strain to a UAS-CD8-GFP reporter strain, and students perform whole mount CNS dissection, immunohistochemistry, confocal imaging, and analysis of developmental expression patterns. We have found these exercises to be very effective in teaching the uses and limitations of PCR and antibody-based techniques as well as critical reading of the primary literature and scientific writing. Students appreciate the opportunity to apply what they learn by generating novel data of use to the wider research community.
9. Structured Inquiry-Based Learning: Drosophila GAL4 Enhancer Trap Characterization in an Undergraduate Laboratory Course
Science.gov (United States)
Dunne, Christopher R.; Cillo, Anthony R.; Glick, Danielle R.; John, Katherine; Johnson, Cody; Kanwal, Jaspinder; Malik, Brian T.; Mammano, Kristina; Petrovic, Stefan; Pfister, William; Rascoe, Alexander S.; Schrom, Diane; Shapiro, Scott; Simkins, Jeffrey W.; Strauss, David; Talai, Rene; Tomtishen, John P.; Vargas, Josephine; Veloz, Tony; Vogler, Thomas O.; Clenshaw, Michael E.; Gordon-Hamm, Devin T.; Lee, Kathryn L.; Marin, Elizabeth C.
2014-01-01
We have developed and tested two linked but separable structured inquiry exercises using a set of Drosophila melanogaster GAL4 enhancer trap strains for an upper-level undergraduate laboratory methods course at Bucknell University. In the first, students learn to perform inverse PCR to identify the genomic location of the GAL4 insertion, using FlyBase to identify flanking sequences and the primary literature to synthesize current knowledge regarding the nearest gene. In the second, we cross each GAL4 strain to a UAS-CD8-GFP reporter strain, and students perform whole mount CNS dissection, immunohistochemistry, confocal imaging, and analysis of developmental expression patterns. We have found these exercises to be very effective in teaching the uses and limitations of PCR and antibody-based techniques as well as critical reading of the primary literature and scientific writing. Students appreciate the opportunity to apply what they learn by generating novel data of use to the wider research community. PMID:25549104
10. Adsorption laboratory experiment for undergraduate chemical engineering: Introducing kinetic, equilibrium and thermodynamic concepts
Science.gov (United States)
2016-11-01
Adsorption laboratory experiment for undergraduate chemical engineering program is discussed. The experiment demonstrated adsorption of copper ions commonly found in wastewater using bio-sorbent, i.e. agricultural wastes. The adsorption was performed in a batch mode under various parameters: adsorption time (up to 120 min), initial pH (2 to 6), adsorbent dose (2.0 to 12.0 g L-1), adsorbent size (50 to 170 mesh), initial Cu2+ concentration (25 to 100 ppm) and temperatures (room temp to 40°C). The equilibrium and kinetic data of the experiments were calculated using the two commonly used isotherms: Langmuir and Lagergren pseudo-first-order kinetics. The maximum adsorption capacity for Cu2+ was found as 94.34 mg g-1. Thermodynamically, the adsorption process was spontaneous and endothermic. The calculated activation energy for the adsorption was observed as high as 127.94 kJ mol-1. Pedagogically, the experiment was assumed to be important in increasing student understanding of kinetic, equilibrium and thermodynamic concepts.
11. Biofouling and microbial corrosion problem in the thermo-fluid heat exchanger and cooling water system of a nuclear test reactor.
Science.gov (United States)
Rao, T S; Kora, Aruna Jyothi; Chandramohan, P; Panigrahi, B S; Narasimhan, S V
2009-10-01
This article discusses aspects of biofouling and corrosion in the thermo-fluid heat exchanger (TFHX) and in the cooling water system of a nuclear test reactor. During inspection, it was observed that >90% of the TFHX tube bundle was clogged with thick fouling deposits. Both X-ray diffraction and Mossbauer analyses of the fouling deposit demonstrated iron corrosion products. The exterior of the tubercle showed the presence of a calcium and magnesium carbonate mixture along with iron oxides. Raman spectroscopy analysis confirmed the presence of calcium carbonate scale in the calcite phase. The interior of the tubercle contained significant iron sulphide, magnetite and iron-oxy-hydroxide. A microbiological assay showed a considerable population of iron oxidizing bacteria and sulphate reducing bacteria (10(5) to 10(6) cfu g(-1) of deposit). As the temperature of the TFHX is in the range of 45-50 degrees C, the microbiota isolated/assayed from the fouling deposit are designated as thermo-tolerant bacteria. The mean corrosion rate of the CS coupons exposed online was approximately 2.0 mpy and the microbial counts of various corrosion causing bacteria were in the range 10(3) to 10(5) cfu ml(-1) in the cooling water and 10(6) to 10(8) cfu ml(-1) in the biofilm.
12. Demand for Interdisciplinary Laboratories for Physiology Research by Undergraduate Students in Biosciences and Biomedical Engineering
Science.gov (United States)
Clase, Kari L.; Hein, Patrick W.; Pelaez, Nancy J.
2008-01-01
Physiology as a discipline is uniquely positioned to engage undergraduate students in interdisciplinary research in response to the 2006-2011 National Science Foundation Strategic Plan call for innovative transformational research, which emphasizes multidisciplinary projects. To prepare undergraduates for careers that cross disciplinary…
13. Formative evaluation of traditional instruction and cooperative inquiry projects in undergraduate chemistry laboratory courses
Science.gov (United States)
Panichas, Michael A.
14. A survey on faculty perspectives on the transition to a biochemistry course-based undergraduate research experience laboratory.
Science.gov (United States)
Craig, Paul A
2017-09-01
It will always remain a goal of an undergraduate biochemistry laboratory course to engage students hands-on in a wide range of biochemistry laboratory experiences. In 2006, our research group initiated a project for in silico prediction of enzyme function based only on the 3D coordinates of the more than 3800 proteins "of unknown function" in the Protein Data Bank, many of which resulted from the Protein Structure Initiative. Students have used the ProMOL plugin to the PyMOL molecular graphics environment along with BLAST, Pfam, and Dali to predict protein functions. As young scientists, these undergraduate research students wanted to see if their predictions were correct and so they developed an approach for in vitro testing of predicted enzyme function that included literature exploration, selection of a suitable assay and the search for commercially available substrates. Over the past two years, a team of faculty members from seven different campuses (California Polytechnic San Luis Obispo, Hope College, Oral Roberts University, Rochester Institute of Technology, St. Mary's University, Ursinus College, and Purdue University) have transferred this approach to the undergraduate biochemistry teaching laboratory as a Course-based Undergraduate Research Experience. A series of ten course modules and eight instructional videos have been created (www.promol.org/home/basil-modules-1) and the group is now expanding these resources, creating assessments and evaluating how this approach helps student to grow as scientists. The focus of this manuscript will be the logistical implications of this transition on campuses that have different cultures, expectations, schedules, and student populations. © 2017 by The International Union of Biochemistry and Molecular Biology, 45(5):426-436, 2017. © 2017 The International Union of Biochemistry and Molecular Biology.
15. Quality of Undergraduate Physics Students' Written Scientific Arguments: How to Promote Students' Appropriation of Scientific Discourse in Physics Laboratory Reports?
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Aydeniz, Mehmet; Yeter-Aydeniz, Kubra
2015-03-01
In this study we challenged 18 undergraduate physics students to develop four written scientific arguments across four physics labs: 1) gravity-driven acceleration, 2) conservation of mechanical energy, 3) conservation of linear momentum and 4) boyle's law, in a mechanics and thermodynamics laboratory course. We evaluated quality of the written scientific arguments developed by the participants using the Claim, Evidence, Reasoning and Rebuttal (CERR) rubric. The results indicate that while students developed adequate scientific explanations that summarized the findings of their experiments, they experienced unique difficulties in using a persuasive and critical discourse in their written arguments. Students experienced the most difficulty in considering alternative explanations in formulating their written scientific arguments. We elaborate on the implications of these findings for teaching physics laboratories and assessing students' learning in physics laboratories. We especially focus on the importance of framing in helping students to appropriate the epistemic norms of science in writing scientific arguments.
16. Fighting Tuberculosis in an Undergraduate Laboratory: Synthesizing, Evaluating and Analyzing Inhibitors
Science.gov (United States)
Daniels, David; Berkes, Charlotte; Nekoie, Arjan; Franco, Jimmy
2015-01-01
A drug discovery project has been successfully implemented in a first-year general, organic, and biochemistry (GOB) health science course and second-year organic undergraduate chemistry course. This project allows students to apply the fundamental principles of chemistry and biology to a problem of medical significance, practice basic laboratory…
17. Solvent Extraction of Copper: An Extractive Metallurgy Exercise for Undergraduate Teaching Laboratories
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Smellie, Iain A.; Forgan, Ross S.; Brodie, Claire; Gavine, Jack S.; Harris, Leanne; Houston, Daniel; Hoyland, Andrew D.; McCaughan, Rory P.; Miller, Andrew J.; Wilson, Liam; Woodhall, Fiona M.
2016-01-01
A multidisciplinary experiment for advanced undergraduate students has been developed in the context of extractive metallurgy. The experiment serves as a model of an important modern industrial process that combines aspects of organic/inorganic synthesis and analysis. Students are tasked to prepare a salicylaldoxime ligand and samples of the…
18. Online Protocol Annotation: A Method to Enhance Undergraduate Laboratory Research Skills
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Ruble, Julie E.; Lom, Barbara
2008-01-01
A well-constructed, step-by-step protocol is a critical starting point for teaching undergraduates new techniques, an important record of a lab's standard procedures, and a useful mechanism for sharing techniques between labs. Many research labs use websites to archive and share their protocols for these purposes. Here we describe our experiences…
19. A Model System for the Study of Gene Expression in the Undergraduate Laboratory
Science.gov (United States)
2016-01-01
The flow of genetic information from DNA to RNA to protein, otherwise known as the "central dogma" of biology, is one of the most basic and overarching concepts in the biological sciences. Nevertheless, numerous studies have reported student misconceptions at the undergraduate level of this fundamental process of gene expression. This…
20. A Cost-Effective Atomic Force Microscope for Undergraduate Control Laboratories
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Jones, C. N.; Goncalves, J.
2010-01-01
This paper presents a simple, cost-effective and robust atomic force microscope (AFM), which has been purposely designed and built for use as a teaching aid in undergraduate controls labs. The guiding design principle is to have all components be open and visible to the students, so the inner functioning of the microscope has been made clear to…
1. Integration of Computational Chemistry into the Undergraduate Organic Chemistry Laboratory Curriculum
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Esselman, Brian J.; Hill, Nicholas J.
2016-01-01
Advances in software and hardware have promoted the use of computational chemistry in all branches of chemical research to probe important chemical concepts and to support experimentation. Consequently, it has become imperative that students in the modern undergraduate curriculum become adept at performing simple calculations using computational…
2. Synthesis and Characterization of Calixarene Tetraethers: An Exercise in Supramolecular Chemistry for the Undergraduate Organic Laboratory
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Debbert, Stefan L.; Hoh, Bradley D.; Dulak, David J.
2016-01-01
In this experiment for an introductory undergraduate organic chemistry lab, students tetraalkylate tertbutylcalix[4]arene, a bowl-shaped macrocyclic oligophenol, and examine the supramolecular chemistry of the tetraether product by proton nuclear magnetic resonance (NMR) spectroscopy. Complexation with a sodium ion reduces the conformational…
3. Rapid Multistep Synthesis of a Bioactive Peptidomimetic Oligomer for the Undergraduate Laboratory
Science.gov (United States)
Utku, Yeliz; Rohatgi, Abhinav; Yoo, Barney; Kirshenbaum, Kent; Zuckermann, Ronald N.; Pohl, Nicola L.
2010-01-01
Peptidomimetic compounds are increasingly important in drug-discovery applications. We introduce the synthesis of an N-substituted glycine oligomer, a bioactive "peptoid" trimer. The six-step protocol is conducted on solid-phase resin, enabling the synthesis to be performed by undergraduate organic chemistry students. This synthesis lab was…
4. Organic Materials in the Undergraduate Laboratory: Microscale Synthesis and Investigation of a Donor-Acceptor Molecule
Science.gov (United States)
Pappenfus, Ted M.; Schliep, Karl B.; Dissanayake, Anudaththa; Ludden, Trevor; Nieto-Ortega, Belen; Lopez Navarrete, Juan T.; Ruiz Delgado, M. Carmen; Casado, Juan
2012-01-01
A series of experiments for undergraduate courses (e.g., organic, physical) have been developed in the area of small molecule organic materials. These experiments focus on understanding the electronic and redox properties of a donor-acceptor molecule that is prepared in a convenient one-step microscale reaction. The resulting intensely colored…
5. Undergraduate Laboratory Experiment Facilitating Active Learning of Concepts in Transport Phenomena: Experiment with a Subliming Solid
Science.gov (United States)
Utgikar, Vivek P.
2015-01-01
An experiment based on the sublimation of a solid was introduced in the undergraduate Transport Phenomena course. The experiment required the students to devise their own apparatus and measurement techniques. The theoretical basis, assignment of the experiment, experimental results, and student/instructor observations are described in this paper.…
6. An Undergraduate Laboratory Class Using CRISPR/Cas9 Technology to Mutate Drosophila Genes
Science.gov (United States)
Adame, Vanesa; Chapapas, Holly; Cisneros, Marilyn; Deaton, Carol; Deichmann, Sophia; Gadek, Chauncey; Lovato, TyAnna L.; Chechenova, Maria B.; Guerin, Paul; Cripps, Richard M.
2016-01-01
CRISPR/Cas9 genome editing technology is used in the manipulation of genome sequences and gene expression. Because of the ease and rapidity with which genes can be mutated using CRISPR/Cas9, we sought to determine if a single-semester undergraduate class could be successfully taught, wherein students isolate mutants for specific genes using…
7. Hydrogen Storage Experiments for an Undergraduate Laboratory Course--Clean Energy: Hydrogen/Fuel Cells
Science.gov (United States)
Bailey, Alla; Andrews, Lisa; Khot, Ameya; Rubin, Lea; Young, Jun; Allston, Thomas D.; Takacs, Gerald A.
2015-01-01
Global interest in both renewable energies and reduction in emission levels has placed increasing attention on hydrogen-based fuel cells that avoid harm to the environment by releasing only water as a byproduct. Therefore, there is a critical need for education and workforce development in clean energy technologies. A new undergraduate laboratory…
8. Aerobic Alcohol Oxidation Using a Copper(I)/TEMPO Catalyst System: A Green, Catalytic Oxidation Reaction for the Undergraduate Organic Chemistry Laboratory
Science.gov (United States)
Hill, Nicholas J.; Hoover, Jessica M.; Stahl, Shannon S.
2013-01-01
Modern undergraduate organic chemistry textbooks provide detailed discussion of stoichiometric Cr- and Mn-based reagents for the oxidation of alcohols, yet the use of such oxidants in instructional and research laboratories, as well as industrial chemistry, is increasingly avoided. This work describes a laboratory exercise that uses ambient air as…
9. Determining the Transference Number of H[superscript +](aq) by a Modified Moving Boundary Method: A Directed Study for the Undergraduate Physical Chemistry Laboratory
Science.gov (United States)
Dabke, Rajeev B.; Gebeyehu, Zewdu; Padelford, Jonathan
2012-01-01
A directed study for the undergraduate physical chemistry laboratory for determining the transference number of H[superscript +](aq) using a modified moving boundary method is presented. The laboratory study combines Faraday's laws of electrolysis with mole ratios and the perfect gas equation. The volume of hydrogen gas produced at the cathode is…
10. Red seaweed enzyme-catalyzed bromination of bromophenol red: An inquiry-based kinetics laboratory experiment for undergraduates.
Science.gov (United States)
Jittam, Piyachat; Boonsiri, Patcharee; Promptmas, Chamras; Sriwattanarothai, Namkang; Archavarungson, Nattinee; Ruenwongsa, Pintip; Panijpan, Bhinyo
2009-03-01
Haloperoxidase enzymes are of interest for basic and applied bioscientists because of their increasing importance in pharmaceutical industry and environmental cleanups. In a guided inquiry-based laboratory experiment for life-science, agricultural science, and health science undergraduates, the bromoperoxidase from a red seaweed was used to brominate bromophenol red, a novel starting substrate. Substrate and enzyme concentration dependence of this enzyme-catalyzed reaction as followed colorimetrically yielded initial rates of reaction that the students compared with those of their peers. The students worked as collaborative groups partially designing their own experiments and carrying them out. In performing the laboratory experiment, they were minimally guided by the instructor and teaching assistants. To engage the students before the laboratory, a short activity involving the enzyme-induced color change was carried out. At the end of the laboratory session, student groups discussed their results in front of the class and reached their own conclusions. Most students had better understanding of important concepts in enzyme kinetics and showed good attitude toward the overall student-centered laboratory exercise. Copyright © 2009 International Union of Biochemistry and Molecular Biology, Inc.
11. RNA Isolation from Plant Tissues: A Hands-on Laboratory Experimental Experience for Undergraduates.
Science.gov (United States)
Zhang, Nianhui; Yu, Dong; Zhu, Xiaofeng
2017-12-29
The practice of RNA isolation in undergraduate experimental courses is rare because of the existence of robust, ubiquitous and stable ribonucleases. We reported here modifications to our original protocol for RNA isolation from plant tissues, including the recovery of nucleic acids by ethanol precipitation at 0 °C for 10 min and the assessment of RNA quality by visualizing the banding profile of the separated RNAs on a standard nondenaturing agarose gel to shorten the duration of the whole procedure and simplify the operation. As a result, the modified procedure, including RNA isolation and quality control analysis could be finished in 4 hr and divided into two sessions. Because endogenous ribonucleases released upon disruption of the organelles and vacuoles were effectively and quickly inactivated, measures were taken to protect RNA integrity throughout the whole procedure so that total RNA with high purity and integrity as well as an appropriate yield could be obtained by students. The RNA isolation protocol described here was simple, efficient, flexible, and low cost. Therefore, it is an ideal approach for undergraduates to learn about RNA techniques. The pedagogical approach of the correlation of experimental work with the rationale for the whole protocol described in this report is an effective way for undergraduates to improve their learning of the techniques of RNA isolation and analysis and the theories behind them, as well as experimental design and data analysis. © 2017 by The International Union of Biochemistry and Molecular Biology, 2017. © 2017 The International Union of Biochemistry and Molecular Biology.
12. Urban Field Experiences for Undergraduate Liberal Arts Students: Using Compromised Environments as Living Laboratories
Science.gov (United States)
MacAvoy, S. E.; Knee, K.
2015-12-01
While urban environments may lack the beauty of relatively pristine field sites, they can be used to deliver an effective demonstration of actual environmental damage. Students demanding applied field experiences from their undergraduate environmental science programs can be well served in urban settings. Here, we present strategies for integrating degraded urban systems into the undergraduate field experience. Urban locations provide an opportunity for a different type of local "field-work" than would otherwise be available. In the upper-level undergraduate Environmental Methods class, we relied on a National Park area located a 10-minute walk from campus for most field exercises. Activities included soil analysis, measuring stream flow and water quality parameters, dendrochronology, and aquatic microbe metabolism. In the non-majors class, we make use of our urban location to contrast water quality in parks and highly channelized urban streams. Students spend labs immersed in streams and wetlands heavily impacted by the urban runoff their city generates. Here we share lesson plans and budgets for field activities that can be completed during a class period of 2.5 hours with a \$75 course fee, show how these activities help students gain quantitative competency.
13. Hormones and Antibiotics in Nature: A Laboratory Module Designed to Broaden Undergraduate Perspectives on Typically Human-Centered Topics
Directory of Open Access Journals (Sweden)
Carolyn F. Weber
2014-07-01
Full Text Available Bringing discovery-based research into undergraduate laboratory courses increases student motivation and learning gains over traditional exercises that merely teach technique or demonstrate well-documented phenomena. Laboratory experiences are further enhanced when they are designed to challenge student perspectives on topics relevant to their lives. To this end, a laboratory module on antibiotics and hormones, which are generally discussed in the context of human health, was developed for students to explore the multifaceted roles of antibiotics and hormones in nature (e.g. interspecies communication via reading primary scientific literature and performing discovery-based experiments. The main objective of this module was to increase the general biological literacy of students as determined by their ability to connect the Five Core Concepts of Biological Literacy (American Association for the Advancement of Science, Vision and Change in Undergraduate Education: A Call to Action, 2011 to the topics “hormones” and “antibiotics” in pre- and postmodule surveys. After discussing unpublished research findings, cell biology students performed experiments demonstrating that: 1 fungi may promote fern growth via hormone production, 2 novel bacterial isolates in the genus Streptomyces produce antifungal compounds, and 3 subinhibitory antibiotic concentrations may enhance soil bacterial growth. The third finding provided evidence supporting a hypothesis framed in a scientific article that students read and discussed. Student perspectives on premodule surveys focused on roles of hormones and antibiotics in the human body (e.g. development, fighting infection, but their broadened postmodule perspectives encompassed the roles of these molecules in organismal communication and possibly the evolution of multicellularity.
14. Hormones and antibiotics in nature: a laboratory module designed to broaden undergraduate perspectives on typically human-centered topics.
Science.gov (United States)
Weber, Carolyn F
2014-12-01
Bringing discovery-based research into undergraduate laboratory courses increases student motivation and learning gains over traditional exercises that merely teach technique or demonstrate well-documented phenomena. Laboratory experiences are further enhanced when they are designed to challenge student perspectives on topics relevant to their lives. To this end, a laboratory module on antibiotics and hormones, which are generally discussed in the context of human health, was developed for students to explore the multifaceted roles of antibiotics and hormones in nature (e.g. interspecies communication) via reading primary scientific literature and performing discovery-based experiments. The main objective of this module was to increase the general biological literacy of students as determined by their ability to connect the Five Core Concepts of Biological Literacy (American Association for the Advancement of Science, Vision and Change in Undergraduate Education: A Call to Action, 2011) to the topics "hormones" and "antibiotics" in pre- and postmodule surveys. After discussing unpublished research findings, cell biology students performed experiments demonstrating that: 1) fungi may promote fern growth via hormone production, 2) novel bacterial isolates in the genus Streptomyces produce antifungal compounds, and 3) subinhibitory antibiotic concentrations may enhance soil bacterial growth. The third finding provided evidence supporting a hypothesis framed in a scientific article that students read and discussed. Student perspectives on premodule surveys focused on roles of hormones and antibiotics in the human body (e.g. development, fighting infection), but their broadened postmodule perspectives encompassed the roles of these molecules in organismal communication and possibly the evolution of multicellularity.
15. Problem-Based Learning in Undergraduate Instruction. A Sophomore Chemistry Laboratory
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Ram, Preetha
1999-08-01
Problem-based learning (PBL) is a pedagogical approach based on recent advances in cognitive science research on human learning. PBL has been used in medical schools for many years. This paper describes the application of PBL in undergraduate courses and discusses the specific needs of this environment. Practical information and guidance are given on how to develop a challenging problem, how to ensure coverage of syllabus topics, how to structure the discussions, and how to evaluate the progress of the course. The paper describes an implementation of PBL methodologies in an undergraduate science course. In this course, students work with a voluntary environmental advocacy group, the Upper Chattahoochee RiverKeeper, to monitor the quality of water in the Chattahoochee watershed. Students learn experimental analytical chemistry techniques and problem-solving skills in this context. A PBL classroom is organized around collaborative problem-solving activities, which provide a context for learning and discovery. Students show enthusiasm and motivation to learn, and they achieve a deeper understanding of the material because it is information they have learned in a context of an interesting problem. PBL also provides them with an opportunity to acquire effective problem-solving techniques and to improve their communication skills and their ability to work in cooperative groups.
16. Using a Logic Model to Evaluate Undergraduate Instruction in a Laboratory Preschool
Science.gov (United States)
Monroe, Lisa; Horm, Diane M.
2012-01-01
Research Findings: Utilization-focused, process evaluations of university-based laboratory preschools in their role with teacher preparation programs are rare in the current literature. This paper describes a self-study evaluation designed and implemented at a university laboratory preschool. A theory approach logic model was developed and used to…
17. UV-Vis Spectrophotometric Analysis and Quantification of Glyphosate for an Interdisciplinary Undergraduate Laboratory
Science.gov (United States)
Felton, Daniel E.; Ederer, Martina; Steffens, Timothy; Hartzell, Patricia L.; Waynant, Kristopher V.
2018-01-01
Glyphosate (N-(phosphonomethyl)glycine) is the most widely used herbicide on earth. A simple assay to quantify glyphosate concentrations in environmental samples was developed as part of an interdisciplinary effort linking introductory laboratory courses in chemistry, biology, and microbiology. In this 3 h laboratory experiment, students used…
18. Using Zebrafish to Implement a Course-Based Undergraduate Research Experience to Study Teratogenesis in Two Biology Laboratory Courses
Science.gov (United States)
Chism, Grady W.; Vaughan, Martin A.; Muralidharan, Pooja; Marrs, Jim A.
2016-01-01
Abstract A course-based undergraduate research experience (CURE) spanning three semesters was introduced into freshman and sophomore biology classes, with the hypothesis that participation in a CURE affects skills in research, communication, and collaboration, which may help students persist in science. Student research projects were centered on the hypothesis that nicotine and caffeine exposure during early development affects gastrulation and heart development in zebrafish. First, freshmen generated original data showing distinct effects of embryonic nicotine and caffeine exposure on zebrafish heart development and function. Next, Cell Biology laboratory students continued the CURE studies and identified novel teratogenic effects of nicotine and caffeine during gastrulation. Finally, new freshmen continued the CURE research, examining additional toxicant effects on development. Students designed new protocols, made measurements, presented results, and generated high-quality preliminary data that were studied in successive semesters. By implementing this project, the CURE extended faculty research and provided a scalable model to address national goals to involve more undergraduates in authentic scientific research. In addition, student survey results support the hypothesis that CUREs provide significant gains in student ability to (1) design experiments, (2) analyze data, and (3) make scientific presentations, translating into high student satisfaction and enhanced learning. PMID:26829498
19. Using particle tracking to measure flow instabilities in an undergraduate laboratory experiment
Science.gov (United States)
Kelley, Douglas H.; Ouellette, Nicholas T.
2011-03-01
Much of the drama and complexity of fluid flow occurs because its governing equations lack unique solutions. The observed behavior depends on the stability of the multitude of solutions, which can change with the experimental parameters. Instabilities cause sudden global shifts in behavior. We have developed a low-cost experiment to study a classical fluid instability. By using an electromagnetic technique, students drive Kolmogorov flow in a thin fluid layer and measure it quantitatively with a webcam. They extract positions and velocities from movies of the flow using Lagrangian particle tracking and compare their measurements to several theoretical predictions, including the effect of the drive current, the spatial structure of the flow, and the parameters at which instability occurs. The experiment can be tailored to undergraduates at any level or to graduate students by appropriate emphasis on the physical phenomena and the sophisticated mathematics that govern them.
20. A laboratory module on radiometry, photometry and colorimetry for an undergraduate optics course
Science.gov (United States)
Polak, Robert D.
2014-07-01
The bachelor's degree in Physics at Loyola University Chicago requires both an upper-division course in Optics as well as a companion Optics Laboratory course. Recently, the laboratory course has undergone dramatic changes. Traditional weekly laboratories have been replaced with three laboratory modules, where students focus on a single topic over several weeks after which the students submit a laboratory report written in the style of a journal article following American Institute of Physics style manual. With this method, students are able to gain a deeper understanding of the specific topic areas of radiometry, photometry and colorimetry, lens design and aberrations, and polarization and interference while using industry-standard equipment and simulation software. In particular, this work will provide the details of the laboratory module on radiometry, photometry and colorimetry where students use a photoradiometer and integrating sphere to characterize the optical properties of an LCD monitor, light bulb and a fiber optic light source calculating properties such as luminous flux, luminous intensity, luminance, CIE color coordinates, NTSC ratio, color temperature and luminous efficacy.
1. The Miracle Fruit: An Undergraduate Laboratory Exercise in Taste Sensation and Perception.
Science.gov (United States)
Lipatova, Olga; Campolattaro, Matthew M
2016-01-01
"Miracle Fruit" is a taste-altering berry that causes sour foods to be perceived as sweet. The present paper describes a laboratory exercise that uses Miracle Fruit to educate students about the sensation and perception of taste. This laboratory exercise reinforces course material pertaining to the function of sweet taste receptors covered in a Sensation and Perception course at Christopher Newport University. Here we provide a step-by-step explanation of the methodology, and an example of data collected and analyzed by one group of students who participated in this laboratory exercise. The origins of the Miracle Fruit, the structure and the physiological function of miraculin (the glycoprotein responsible for the taste-modifying effect found in the pulp of the Miracle Fruit) were discussed before the laboratory exercise. Students then sampled foods known to target different types of tastes (i.e., sweet, sour, bitter and salty) and rated their perception of taste intensity for each food item. Next, students each consumed Miracle Fruit berries, then resampled each original food item and again recorded their perception of taste intensity ratings for these foods. The data confirmed that the sour food items were perceived sweeter after the Miracle Fruit was consumed. The students also completed a written assignment to assess what they learned about the origins, structure, and physiological function of Miracle Fruit. This hands-on laboratory exercise received positive feedback from students. The exercise can be used by other neuroscience educators to teach concepts related to the sensory system of taste.
2. Preparation of a Cobalt(II) Cage: An Undergraduate Laboratory Experiment That Produces a ParaSHIFT Agent for Magnetic Resonance Spectroscopy
Science.gov (United States)
Burns, Patrick J.; Tsitovich, Pavel B.; Morrow, Janet R.
2016-01-01
Laboratory experiments that demonstrate the effect of paramagnetic complexes on chemical shifts and relaxation times of protons are a useful way to introduce magnetic resonance spectroscopy (MRS) probes or magnetic resonance imaging (MRI) contrast agents. In this undergraduate inorganic chemistry experiment, a paramagnetic Co(II) cage complex is…
3. Introduction of a Simple Experiment for the Undergraduate Organic Chemistry Laboratory Demonstrating the Lewis Acid and Shape-Selective Properties of Zeolite Na-Y
Science.gov (United States)
Maloney, Vincent; Szczepanski, Zach
2017-01-01
A simple, inexpensive, discovery-based experiment for undergraduate organic laboratories has been developed that demonstrates the Lewis acid and shape-selective properties of zeolites. Calcined zeolite Na-Y promotes the electrophilic aromatic bromination of toluene with a significantly higher para/ortho ratio than observed under conventional…
4. Virtual and Traditional Slides for Teaching Cellular Morphology to Medical Laboratory Science Undergraduates: A Comparative Study of Performance Outcomes, Retention, and Self-Efficacy Beliefs
Science.gov (United States)
Solberg, Brooke L.
2011-01-01
As a result of massive retirement and educational program expense and closure, the field of Medical Laboratory Science (MLS) is facing a critical workforce shortage. Combatting this issue by increasing undergraduate class size is a difficult proposition due to the intense psychomotor curricular requirements of MLS programs. Technological advances…
5. A Western Blot-based Investigation of the Yeast Secretory Pathway Designed for an Intermediate-Level Undergraduate Cell Biology Laboratory
Science.gov (United States)
Hood-DeGrenier, Jennifer K.
2008-01-01
The movement of newly synthesized proteins through the endomembrane system of eukaryotic cells, often referred to generally as the secretory pathway, is a topic covered in most intermediate-level undergraduate cell biology courses. An article previously published in this journal described a laboratory exercise in which yeast mutants defective in…
6. A Research-Based Undergraduate Organic Laboratory Project: Investigation of a One-Pot, Multicomponent, Environmentally Friendly Prins-Friedel-Crafts-Type Reaction
Science.gov (United States)
Dintzner, Matthew R.; Maresh, Justin J.; Kinzie, Charles R.; Arena, Anthony F.; Speltz, Thomas
2012-01-01
Students in the undergraduate organic laboratory synthesize tetrahydro-2-(4-nitrophenyl)-4-phenyl-2"H"-pyran via the Montmorillonite K10 clay-catalyzed reaction of p-nitrobenzaldehye with methanol, 3-buten-1-ol, and benzene. The synthesis comprises an environmentally friendly tandem Prins-Friedel-Crafts-type multicomponent reaction (MCR) and sets…
7. Synthesis and Catalytic Activity of Ruthenium-Indenylidene Complexes for Olefin Metathesis: Microscale Experiments for the Undergraduate Inorganic or Organometallic Laboratories
Science.gov (United States)
Pappenfus, Ted M.; Hermanson, David L.; Ekerholm, Daniel P.; Lilliquist, Stacie L.; Mekoli, Megan L.
2007-01-01
A series of experiments for undergraduate laboratory courses (e.g., inorganic, organometallic or advanced organic) have been developed. These experiments focus on understanding the design and catalytic activity of ruthenium-indenylidene complexes for olefin metathesis. Included in the experiments are the syntheses of two ruthenium-indenylidene…
8. Ligand-Free Suzuki-Miyaura Coupling Reactions Using an Inexpensive Aqueous Palladium Source: A Synthetic and Computational Exercise for the Undergraduate Organic Chemistry Laboratory
Science.gov (United States)
Hill, Nicholas J.; Bowman, Matthew D.; Esselman, Brian J.; Byron, Stephen D.; Kreitinger, Jordan; Leadbeater, Nicholas E.
2014-01-01
An inexpensive procedure for introducing the Suzuki-Miyaura coupling reaction into a high-enrollment undergraduate organic chemistry laboratory course is described. The procedure employs an aqueous palladium solution as the catalyst and a range of para-substituted aryl bromides and arylboronic acids as substrates. The coupling reactions proceed…
9. Volumetric Titrations Using Electrolytically Generated Reagents for the Determination of Ascorbic Acid and Iron in Dietary Supplement Tablets: An Undergraduate Laboratory Experiment
Science.gov (United States)
Scanlon, Christopher; Gebeyehu, Zewdu; Griffin, Kameron; Dabke, Rajeev B.
2014-01-01
An undergraduate laboratory experiment for the volumetric quantitative analysis of ascorbic acid and iron in dietary supplement tablets is presented. Powdered samples of the dietary supplement tablets were volumetrically titrated against electrolytically generated reagents, and the mass of dietary reagent in the tablet was determined from the…
10. A Simplified Undergraduate Laboratory Experiment to Evaluate the Effect of the Ionic Strength on the Equilibrium Concentration Quotient of the Bromcresol Green Dye
Science.gov (United States)
Rodriguez, Hernan B.; Mirenda, Martin
2012-01-01
A modified laboratory experiment for undergraduate students is presented to evaluate the effects of the ionic strength, "I", on the equilibrium concentration quotient, K[subscript c], of the acid-base indicator bromcresol green (BCG). The two-step deprotonation of the acidic form of the dye (sultone form), as it is dissolved in water, yields…
11. Using Mole Ratios of Electrolytic Products of Water for Analysis of Household Vinegar: An Experiment for the Undergraduate Physical Chemistry Laboratory
Science.gov (United States)
Dabke, Rajeev B.; Gebeyehu, Zewdu
2012-01-01
A simple 3-h physical chemistry undergraduate experiment for the quantitative analysis of acetic acid in household vinegar is presented. The laboratory experiment combines titration concept with electrolysis and an application of the gas laws. A vinegar sample was placed in the cathode compartment of the electrolysis cell. Electrolysis of water…
12. Changing undergraduate human anatomy and physiology laboratories: perspectives from a large-enrollment course.
Science.gov (United States)
Griff, Edwin R
2016-09-01
In the present article, a veteran lecturer of human anatomy and physiology taught several sections of the laboratory component for the first time and shares his observations and analysis from this unique perspective. The article discusses a large-enrollment, content-heavy anatomy and physiology course in relationship to published studies on learning and student self-efficacy. Changes in the laboratory component that could increase student learning are proposed. The author also points out the need for research to assess whether selective curricular changes could increase the depth of understanding and retention of learned material. Copyright © 2016 The American Physiological Society.
13. Biocatalyzed Regioselective Synthesis in Undergraduate Organic Laboratories: Multistep Synthesis of 2-Arachidonoylglycerol
Science.gov (United States)
Johnston, Meghan R.; Makriyannis, Alexandros; Whitten, Kyle M.; Drew, Olivia C.; Best, Fiona A.
2016-01-01
In order to introduce the concepts of biocatalysis and its utility in synthesis to organic chemistry students, a multistep synthesis of endogenous cannabinergic ligand 2-arachidonoylglycerol (2-AG) was tailored for use as a laboratory exercise. Over four weeks, students successfully produced 2-AG, purifying and characterizing products at each…
14. A Metabolic Murder Mystery: A Case-Based Experiment for the Undergraduate Biochemistry Laboratory
Science.gov (United States)
Childs-Disney, Jessica L.; Kauffmann, Andrew D.; Poplawski, Shane G.; Lysiak, Daniel R.; Stewart, Robert J.; Arcadi, Jane K.; Dinan, Frank J.
2010-01-01
In 1990, a woman was wrongly convicted of poisoning her infant son and was sentenced to life in prison. Her conviction was based on laboratory work that wrongly identified ethylene glycol as present in her son's blood and in the formula he drank prior to his death. The actual cause of the infant's death, a metabolic disease, was eventually…
15. Dehydration of 2-Methyl-1-Cyclohexanol: New Findings from a Popular Undergraduate Laboratory Experiment
Science.gov (United States)
Friesen, J. Brent; Schretzman, Robert
2011-01-01
The mineral acid-catalyzed dehydration of 2-methyl-1-cyclohexanol has been a popular laboratory exercise in second-year organic chemistry for several decades. The dehydration experiment is often performed by organic chemistry students to illustrate Zaitsev's rule. However, sensitive analytical techniques reveal that the results do not entirely…
16. Computer Based Learning in an Undergraduate Physics Laboratory: Interfacing and Instrument Control Using Matlab
Science.gov (United States)
Sharp, J. S.; Glover, P. M.; Moseley, W.
2007-01-01
In this paper we describe the recent changes to the curriculum of the second year practical laboratory course in the School of Physics and Astronomy at the University of Nottingham. In particular, we describe how Matlab has been implemented as a teaching tool and discuss both its pedagogical advantages and disadvantages in teaching undergraduate…
17. To What Extent Does A-Level Physics Prepare Students for Undergraduate Laboratory Work?
Science.gov (United States)
Thompson, Alaric
2012-01-01
This paper is a summary of a small-scale research project carried out to investigate the transition from A-level to university physics, with a specific focus on practical or laboratory skills. A brief description of the methods used precedes the headline findings of the research. A non-evidential discussion of the possible reasons behind any…
18. Successful Implementation of Inquiry-Based Physiology Laboratories in Undergraduate Major and Nonmajor Courses
Science.gov (United States)
Casotti, G.; Rieser-Danner, L.; Knabb, M. T.
2008-01-01
Recent evidence has demonstrated that inquiry-based physiology laboratories improve students' critical- and analytical-thinking skills. We implemented inquiry-based learning into three physiology courses: Comparative Vertebrate Physiology (majors), Human Physiology (majors), and Human Anatomy and Physiology (nonmajors). The aims of our curricular…
19. Studying Epigenetic DNA Modifications in Undergraduate Laboratories Using Complementary Bioinformatic and Molecular Approaches
Science.gov (United States)
Militello, Kevin T.
2013-01-01
Epigenetic inheritance is the inheritance of genetic information that is not based on DNA sequence alone. One type of epigenetic information that has come to the forefront in the last few years is modified DNA bases. The most common modified DNA base in nature is 5-methylcytosine. Herein, we describe a laboratory experiment that combines…
20. Gravimetric Analysis of Bismuth in Bismuth Subsalicylate Tablets: A Versatile Quantitative Experiment for Undergraduate Laboratories
Science.gov (United States)
Davis, Eric; Cheung, Ken; Pauls, Steve; Dick, Jonathan; Roth, Elijah; Zalewski, Nicole; Veldhuizen, Christopher; Coeler, Joel
2015-01-01
In this laboratory experiment, lower- and upper-division students dissolved bismuth subsalicylate tablets in acid and precipitated the resultant Bi[superscript 3+] in solution with sodium phosphate for a gravimetric determination of bismuth subsalicylate in the tablets. With a labeled concentration of 262 mg/tablet, the combined data from three…
1. Climate-Literacy Laboratory Exercises for Undergraduate Students in an Introductory Weather and Climate Course
Science.gov (United States)
Diem, J.; Elliott, W.; Criswell, B.; Morrow, C. A.
2012-12-01
A suite of NASA-sponsored, Web-based exercises are in development for an introductory weather and climate course at Georgia State University (GSU) to improve climate literacy among undergraduate students. An extremely small percentage of the students are STEM majors. The exercises make extensive use of NASA resources and are guided in part by the concepts in Climate Literacy: The Essential Principles of Climate Science. At least two thousand undergraduate students have completed a majority of the exercises over the past two years. Nine of the twelve exercises in the course are connected strongly to climate literacy. The topics of those nine exercises are as follows: (1) Solar Irradiance, (2) Stratospheric Ozone, (3) Tropospheric Air, (4) The Carbon Cycle, (5) Global Surface Temperature, (6) Glacial-Interglacial Cycles, (7) Temperature Changes during the Past Millennium, (8) Climate & Ecosystems, and (9) Current & Future Climate Change. Two of the exercises (Tropospheric Air and The Carbon Cycle) make use of carbon dioxide (CO2) measurements made by students themselves and by a stationary CO2 monitor at GSU. The three remaining exercises, The Hadley Cell, Atlanta Weather, and Air Pollution, are less connected to multiple climate-literacy concepts; nonetheless, they provide a more complete experience for the students in the understanding of climate processes, differences between weather and climate, and human impacts on the atmosphere. All exercises are based on an inquiry-based learning cycle (i.e. 7 Es) and require substantial amounts of engagement, applied thinking, and critical thinking by the students. Not only do students become knowledgeable about the essential principles of climate change, especially global warming, but extensive use of geographical-information software and hand-held measurement devices has provided students with training in geography and technology. Student attitudes towards the labs were gathered via an on-line, anonymous survey from
2. The effectiveness and user perception of 3-dimensional digital human anatomy in an online undergraduate anatomy laboratory
Science.gov (United States)
2007-12-01
The primary purpose of this study was to determine the effectiveness of implementing desktop 3-dimensional (3D) stereo images of human anatomy into an undergraduate human anatomy distance laboratory. User perceptions of 2D and 3D images were gathered via questionnaire in order to determine ease of use and level of satisfaction associated with the 3D software in the online learning environment. Mayer's (2001, p. 184) principles of design were used to develop the study materials that consisted of PowerPoint presentations and AVI files accessed via Blackboard. The research design employed a mixed-methods approach. Volunteers each were administered a demographic survey and were then stratified into groups based upon pre-test scores. A total sample size of 62 pairs was available for combined data analysis. Quantitative research questions regarding the effectiveness of 2D versus the 3D treatment were analyzed using a doubly-multivariate repeated measures (Doubly-MANOVA) design. Paired test scores achieved by undergraduates on a laboratory practical of identification and spatial relationships of the bones and features of a human skull were used in the analysis. The questionnaire designed to gather user perceptions consisted of quantitative and qualitative questions. Response frequencies were analyzed for the two groups and common themes were noted. Results revealed a statistically significant difference in group means for the main effect of the treatment groups 2D and 3D and for the variables of identification and relationship with the 3D group outperforming the 2D group on both dependent variables. Effect sizes were determined to be small, 0.215 for the identification variable and 0.359 for the relationship variable. Overall, all students liked the convenience of using PowerPoint and AVI files online. The 3D group felt their PowerPoint was more realistic than did the 2D group and both groups appreciated the detailed labeling of the online images. One third of the
3. Student-Driven Engagement: An Interdisciplinary-Team Research-Learning Renewable Energy Laboratory Experience for Undergraduates
Science.gov (United States)
Tuominen, Mark
How does engagement and deep learning happen? Every science department seeks to cultivate an excellent level of scientific skills and knowledge in its undergraduate students. Yet, this is not sufficient to thrive as a professional. Engaging directly in real-world challenges can foster a professional attitude: a high level of self-efficacy, a genuine sense of relevance, and proactivity. This talk will describe pedagogical developments of a junior-year renewable energy laboratory course at the University of Massachusetts Amherst that is part of a four-year Integrated Concentration in Science (iCons) program. Over the four years, the interdisciplinary iCons students-from 24 various majors-work through case studies, selection and analysis of real-world problems, inception and development of potential solutions, integrative communication, experimental practice, and capstone research. The team dynamic is a central aspect of the experience, yielding significant educational and developmental benefits. The third-year energy course uses adopts a culture of a small vibrant R and D company (I3E - Energy, Powered By Intelligence''), in which every person in the course has a vital responsibility and creative resourcefulness must be employed in the project work. The course emphasizes the practice of using reflection and redesign, as a means of generating better solutions and embedding the practice of learning in a real-world context. This work is supported in part by NSF Grant DUE-1140805.
4. An analysis of cognitive growth of undergraduate students in a problem-centered general chemistry laboratory curriculum
Science.gov (United States)
Szeto, Alan Ka-Fai
5. Integrating a Discovery-Based Laboratory to Teach Supply Chain Management Fundamentals in an Undergraduate Management Course
Science.gov (United States)
Zeng, Amy; Johnson, Sharon
2009-01-01
Using experiential simulation games is a commonly used pedagogical method to enrich classroom discussions and to facilitate students' learning in supply chain management education at both undergraduate and graduate levels. However, existing games are inappropriate for undergraduate students that are first-time learners of the subject. In this…
6. Two Successful Outreach Programs at Storm Peak Laboratory: GRASP for Undergraduates and Partnership for 5th Grade Science Education
Science.gov (United States)
Hallar, A. G.; McCubbin, I. B.; Wright, J.
2007-12-01
The Desert Research Institute operates a high elevation facility, Storm Peak Laboratory (SPL), located on the Steamboat Springs Ski Resort at an elevation 10,500 ft. SPL provides an ideal location for long-term atmospheric research. The SPL mission statement is to ensure that the laboratory will continue to integrate climate research and education by advancing discovery and understanding within the field of pollution, aerosol and cloud interactions. During the last year, SPL has created two successful outreach programs reaching very different audiences. First, to engage students from local elementary schools, SPL established a 5th grade climate education program. This program is based on a partnership between SPL and Yampatika's&penvironmental educators. Yampatika is a non-profit outdoor environmental education organization. The program spans three days for each school and includes five elementary schools. During the first day, educators from Yampatika visit each classroom to introduce the concepts of climate and weather as well as teach students how to use scientific equipment. During the field program on the second day, students measure and record information about temperature, pressure, relative humidity, wind speed, and particle concentration while they travel to SPL via the gondola (in winter) or Suburban (in fall). Once at the laboratory, students tour the facility, discuss SPL research activities, and explore application of these activities to their curriculum. Following the field trip, Yampatika educators and SPL scientists will visit the school for a follow-up to help children explore concepts, answer questions, and evaluate students" learning. The second program, Geoscience Research at Storm Peak (GRASP), was designed to engage students from underrepresented groups and created a partnership between three Minority Serving Institutions and the University of Nevada, Reno (UNR). Undergraduate students from Tennessee State University, Howard University
7. Embedding Hands-On Mini Laboratory Experiences in a Core Undergraduate Fluid Mechanics Course: A Pilot Study
Science.gov (United States)
Han, Duanduan; Ugaz, Victor
2017-01-01
Three self-contained mini-labs were integrated into a core undergraduate fluid mechanics course, with the goal of delivering hands-on content in a manner scalable to large class sizes. These mini-labs supported learning objectives involving friction loss in pipes, flow measurement, and centrifugal pump analysis. The hands-on experiments were…
8. Modeling Stretching Modes of Common Organic Molecules with the Quantum Mechanical Harmonic Oscillator: An Undergraduate Vibrational Spectroscopy Laboratory Exercise
Science.gov (United States)
Parnis, J. Mark; Thompson, Matthew G. K.
2004-01-01
An introductory undergraduate physical organic chemistry exercise that introduces the harmonic oscillator's use in vibrational spectroscopy is developed. The analysis and modeling exercise begins with the students calculating the stretching modes of common organic molecules with the help of the quantum mechanical harmonic oscillator (QMHO) model.
9. qHNMR Analysis of Purity of Common Organic Solvents--An Undergraduate Quantitative Analysis Laboratory Experiment
Science.gov (United States)
Bell, Peter T.; Whaley, W. Lance; Tochterman, Alyssa D.; Mueller, Karl S.; Schultz, Linda D.
2017-01-01
NMR spectroscopy is currently a premier technique for structural elucidation of organic molecules. Quantitative NMR (qNMR) methodology has developed more slowly but is now widely accepted, especially in the areas of natural product and medicinal chemistry. However, many undergraduate students are not routinely exposed to this important concept.…
10. Azeotropic Preparation of a "C"-Phenyl "N"-Aryl Imine: An Introductory Undergraduate Organic Chemistry Laboratory Experiment
Science.gov (United States)
Silverberg, Lee J.; Coyle, David J.; Cannon, Kevin C.; Mathers, Robert T.; Richards, Jeffrey A.; Tierney, John
2016-01-01
Imines are important in biological chemistry and as intermediates in organic synthesis. An experiment for introductory undergraduate organic chemistry is presented in which benzaldehyde was condensed with "p"-methoxyaniline in toluene to give 4-methoxy-"N"-(phenylmethylene)benzenamine. Water was removed by azeotropic…
11. Immersing Undergraduate Students in the Research Experience: A Practical Laboratory Module on Molecular Cloning of Microbial Genes
Science.gov (United States)
Wang, Jack T. H.; Schembri, Mark A.; Ramakrishna, Mathitha; Sagulenko, Evgeny; Fuerst, John A.
2012-01-01
Molecular cloning skills are an essential component of biological research, yet students often do not receive this training during their undergraduate studies. This can be attributed to the complexities of the cloning process, which may require many weeks of progressive design and experimentation. To address this issue, we incorporated an…
12. Determination of Surface Tension of Surfactant Solutions through Capillary Rise Measurements: An Image-Processing Undergraduate Laboratory Experiment
Science.gov (United States)
Huck-Iriart, Cristia´n; De-Candia, Ariel; Rodriguez, Javier; Rinaldi, Carlos
2016-01-01
In this work, we described an image processing procedure for the measurement of surface tension of the air-liquid interface using isothermal capillary action. The experiment, designed for an undergraduate course, is based on the analysis of a series of solutions with diverse surfactant concentrations at different ionic strengths. The objective of…
13. The Genomics Education Partnership: Successful Integration of Research into Laboratory Classes at a Diverse Group of Undergraduate Institutions
Science.gov (United States)
Shaffer, Christopher D.; Alvarez, Consuelo; Bailey, Cheryl; Barnard, Daron; Bhalla, Satish; Chandrasekaran, Chitra; Chandrasekaran, Vidya; Chung, Hui-Min; Dorer, Douglas R.; Du, Chunguang; Eckdahl, Todd T.; Poet, Jeff L.; Frohlich, Donald; Goodman, Anya L.; Gosser, Yuying; Hauser, Charles; Hoopes, Laura L. M.; Johnson, Diana; Jones, Christopher J.; Kaehler, Marian; Kokan, Nighat; Kopp, Olga R.; Kuleck, Gary A.; McNeil, Gerard; Moss, Robert; Myka, Jennifer L.; Nagengast, Alexis; Morris, Robert; Overvoorde, Paul J.; Shoop, Elizabeth; Parrish, Susan; Reed, Kelynne; Regisford, E. Gloria; Revie, Dennis; Rosenwald, Anne G.; Saville, Ken; Schroeder, Stephanie; Shaw, Mary; Skuse, Gary; Smith, Christopher; Smith, Mary; Spana, Eric P.; Spratt, Mary; Stamm, Joyce; Thompson, Jeff S.; Wawersik, Matthew; Wilson, Barbara A.; Youngblom, Jim; Leung, Wilson; Buhler, Jeremy; Mardis, Elaine R.; Lopatto, David; Elgin, Sarah C. R.
2010-01-01
Genomics is not only essential for students to understand biology but also provides unprecedented opportunities for undergraduate research. The goal of the Genomics Education Partnership (GEP), a collaboration between a growing number of colleges and universities around the country and the Department of Biology and Genome Center of Washington…
14. Becoming a scientist: A qualitative study of the educational experience of undergraduates working in an American and a Brazilian research laboratory
Science.gov (United States)
Pascoa, Maria Beatriz Amorim
Because the production of scientific and technological innovations has been at the center of debates for economic growth, scientists are recognized as important actors in the current global market. In this study, I will examine the undergraduate education of future scientists by focusing on students working in research projects of faculty members. This research activity has been promoted by American and Brazilian public agencies as an attempt to attract more college students to scientific careers as well as to improve their future performance in science. Evaluations of these programs have focused on important quantitative indicators focusing mainly on the amount of students that later choose to pursue scientific careers. However, these studies fail to address important educational aspects of undergraduates' experience. In this research, I explore the educational processes taking place as students are introduced to the making of science in order to understand how and what they are learning. Three bodies of literature illuminates the formulation and the analysis of the research questions: (1) theories of globalization situate the education of scientists within the dynamics of a broader social, economic, cultural, and historical framework; (2) the critical pedagogy of Paulo Freire is the basis for the understanding of the pedagogical processes shaping undergraduate students' experiences within the research site; (3) Critical and Cultural Studies of Science and Technology illuminate the analysis of the complex interactions and practices constructed within the laboratory. In order to understand the educational processes shaping the experiences of undergraduate students engaged in research activities, I conducted a qualitative investigation based on participant-observation and in-depth interviews in an American and a Brazilian laboratories. The two sites constituted insightful case studies that illuminated the understanding of inquires about the training of students in
15. Undergraduate nursing students' experiences when examining nursing skills in clinical simulation laboratories with high-fidelity patient simulators: A phenomenological research study.
Science.gov (United States)
Sundler, Annelie J; Pettersson, Annika; Berglund, Mia
2015-12-01
Simulation has become a widely used and established pedagogy for teaching clinical nursing skills. Nevertheless, the evidence in favour of this pedagogical approach is weak, and more knowledge is needed in support of its use. The aim of this study was (a) to explore the experiences of undergraduate nursing students when examining knowledge, skills and competences in clinical simulation laboratories with high-fidelity patient simulators and (b) to analyse these students' learning experiences during the examination. A phenomenological approach was used, and qualitative interviews were conducted among 23 second-year undergraduate nursing students-17 women and 6 men. The findings revealed that, irrespective of whether they passed or failed the examination, it was experienced as a valuable assessment of the students' knowledge and skills. Even if the students felt that the examination was challenging, they described it as a learning opportunity. In the examination, the students were able to integrate theory with practice, and earlier established knowledge was scrutinised when reflecting on the scenarios. The examination added aspects to the students' learning that prepared them for the real world of nursing in a safe environment without risking patient safety. The study findings suggest that examinations in clinical simulation laboratories can be a useful teaching strategy in nursing education. The use of high-fidelity patient simulators made the examination authentic. The reflections and feedback on the scenario were described as significant for the students' learning. Undergraduate nursing students can improve their knowledge, understanding, competence and skills when such examinations are performed in the manner used in this study. Copyright © 2015 Elsevier Ltd. All rights reserved.
16. Environmental regulation of plant gene expression: an RT-qPCR laboratory project for an upper-level undergraduate biochemistry or molecular biology course.
Science.gov (United States)
Eickelberg, Garrett J; Fisher, Alison J
2013-01-01
We present a novel laboratory project employing "real-time" RT-qPCR to measure the effect of environment on the expression of the FLOWERING LOCUS C gene, a key regulator of floral timing in Arabidopsis thaliana plants. The project requires four 3-hr laboratory sessions and is aimed at upper-level undergraduate students in biochemistry or molecular biology courses. The project provides students with hands-on experience with RT-qPCR, the current "gold standard" for gene expression analysis, including detailed data analysis using the common 2-ΔΔCT method. Moreover, it provides a convenient starting point for many inquiry-driven projects addressing diverse questions concerning ecological biochemistry, naturally occurring genetic variation, developmental biology, and the regulation of gene expression in nature. Copyright © 2013 Wiley Periodicals, Inc.
17. The use of U.S. Geological Survey CD-ROM-based petroleum assessments in undergraduate geology laboratories
Science.gov (United States)
Eves, R.L.; Davis, L.E.; Dyman, T.S.; Takahashi, K.I.
2002-01-01
Domestic oil production is declining and United States reliance on imported oil is increasing. America will be faced with difficult decisions that address the strategic, economic, and political consequences of its energy resources shortage. The geologically literate under-graduate student needs to be aware of current and future United States energy issues. The U.S. Geological Survey periodically provides energy assessment data via digitally-formatted CD-ROM publications. These publications are free to the public, and are well suited for use in undergraduate geology curricula. The U.S. Geological Survey (USGS) 1995 National Assessment of United States Oil and Gas Resources (Digital Data Series or DDS-30) (Gautier and others, 1996) is an excellent resource for introducing students to the strategies of hydrocarbon exploration and for developing skills in problem-solving and evaluating real data. This paper introduces the reader to DDS-30, summarizes the essential terminology and methodology of hydrocarbon assessment, and offers examples of exercises or questions that might be used in the introductory classroom. The USGS contact point for obtaining DDS-30 and other digital assessment volumes is also provided. Completing the sample exercises in this report requires a copy of DDS-30.
18. Team-Based Learning, Faculty Research, and Grant Writing Bring Significant Learning Experiences to an Undergraduate Biochemistry Laboratory Course
Science.gov (United States)
Evans, Hedeel Guy; Heyl, Deborah L.; Liggit, Peggy
2016-01-01
This biochemistry laboratory course was designed to provide significant learning experiences to expose students to different ways of succeeding as scientists in academia and foster development and improvement of their potential and competency as the next generation of investigators. To meet these goals, the laboratory course employs three…
19. Clays as mineral dust aerosol: An integrated approach to studying climate, atmospheric chemistry, and biogeochemical effects of atmospheric clay minerals in an undergraduate research laboratory
Science.gov (United States)
Hatch, C. D.; Crane, C. C.; Harris, K. J.; Thompson, C. E.; Miles, M. K.; Weingold, R. M.; Bucuti, T.
2011-12-01
Entrained mineral dust aerosol accounts for 45% of the global annual atmospheric aerosol load and can have a significant influence on important environmental issues, including climate, atmospheric chemistry, cloud formation, biogeochemical processes, visibility, and human health. 70% of all mineral aerosol mass originating from Africa consists of layered aluminosilicates, including illite, kaolinite, and montmorillonite clays. Clay minerals are a largely neglected component of mineral aerosol, yet they have unique physiochemical properties, including a high reactive surface area, large cation exchange capacities, small particle sizes, and a relatively large capacity to take up adsorbed water, resulting in expansion of clay layers (and a larger reactive surface area for heterogeneous interactions) in some cases. An integrated laboratory research approach has been implemented at Hendrix College, a Primarily Undergraduate Institution, in which undergraduate students are involved in independent and interdisciplinary research projects that relate the chemical aging processes (heterogeneous chemistry) of clay minerals as a major component of mineral aerosol to their effects on climate (water adsorption), atmospheric chemistry (trace gas uptake), and biogeochemistry (iron dissolution and phytoplankton biomarker studies). Preliminary results and future directions will be reported.
20. Infrared Thermography for Thermo-Fluid-Dynamics
CERN Document Server
Astarita, Tommaso
2013-01-01
Infrared thermography is a measurement technique that enables to obtain non intrusive measurements of surface temperatures. One of the interesting features of this technique is its ability to measure a full two dimensional map of an object surface temperature and, for this reason, it has been widely used as a surface flow visualization technique. Since the temperature measurements can be extremely accurate, it is possible, by using a heat flux sensor, also to measure convective heat transfer coefficient distributions on a surface, making the technique de facto quantitative. This book, starting from the basic theory of radiation and heat flux sensors, guides, both the experienced researcher and the young student, in the correct application of this powerful technique to study convective heat transfer problems. A significant number of examples and applications are also examined in detail, often pointing out some relevant aspects.
1. Dynamic Modeling of ThermoFluid Systems
DEFF Research Database (Denmark)
Jensen, Jakob Munch
2003-01-01
The objective of the present study has been to developed dynamic models for two-phase flow in pipes (evaporation and condensation). Special attention has been given to modeling evaporators for refrigeration plant particular dry-expansion evaporators. Models of different complexity have been...... formulated. The different models deviate with respect to the detail¿s included and calculation time in connection with simulation. The models have been implemented in a new library named ThermoTwoPhase to the programming language Modelica. A test rig has been built with an evaporator instrumented in a way...... that the models can be validated against experimental data. The models developed van be used in connection with intelligent control of refrigerant flow to dry-expansion evaporators....
2. Impact of backwards faded scaffolding approach to inquiry-based astronomy laboratory experiences on undergraduate non-science majors' views of scientific inquiry
Science.gov (United States)
Lyons, Daniel J.
This study explored the impact of a novel inquiry-based astronomy laboratory curriculum designed using the Backwards Faded Scaffolding inquiry teaching framework on non-science majoring undergraduate students' views of the nature of scientific inquiry (NOSI). The study focused on two aspects of NOSI: The Distinction between Data and Evidence (DvE), and The Multiple Methods of Science (MMS). Participants were 220 predominately non-science majoring undergraduate students at a small, doctoral granting, research-extensive university in the Rocky Mountain region of the United States. The student participants were enrolled in an introductory astronomy survey course with an associated laboratory section and were selected in two samples over consecutive fall and spring semesters. The participants also included four of the graduate student instructors who taught the laboratory courses using the intervention curriculum. In the first stage, student participant views of NOSI were measured using the VOSI-4 research instrument before and after the intervention curriculum was administered. The responses were quantified, and the distributions of pre and posttest scores of both samples were separately analyzed to determine if there was a significant improvement in understanding of either of the two aspects of NOSI. The results from both samples were compared to evaluate the consistency of the results. In the second stage, the quantitative results were used to strategically design a qualitative investigation, in which the four lab instructors were interviewed about their observations of how the student participants interacted with the intervention curriculum as compared to traditional lab activities, as well as their suggestions as to how the curriculum may or may not have contributed to the results of the first stage. These interviews were summarized and analyzed for common themes as to how the intervention curriculum influenced the students' understandings of the two aspect of
3. Design and operation of an inexpensive far-field laser scanning microscope suitable for use in an undergraduate laboratory course
Science.gov (United States)
Pallone, Arthur; Hawk, Eric
2013-03-01
Scanning microscope applications span the science disciplines yet their costs limit their use at educational institutions. The basic concepts of scanning microscopy are simple. The microscope probe - whether it produces a photon, electron or ion beam - moves relative to the surface of the sample object. The beam interacts with the sample to produce a detected signal that depends on the desired property to be measured at the probe location on the sample. The microscope transforms the signal for output in a form desired by the user. Undergraduate students can easily construct a far-field laser scanning microscope that illustrates each of these principles from parts available at local electronics and hardware stores and use the microscope to explore properties of devices such as light dependent resistors and biological samples such as leaves. Students can record, analyze and interpret results using a computer and free software.
4. Preparation of (+)-{alpha}-terpineol from (+)-limonene: monoterpenes with pleasant odor in a project for undergraduate organic chemistry laboratory; Preparacao do (+)-{alpha}-terpineola a partir do (+)-limoneno: monoterpenos de odor agradavel em um projeto para quimica organica experimental
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Baptistella, Lucia Helena Brito; Imamura, Paulo Mitsuo; Melo, Leandro Vilela de; Castello, Claudio [Universidade Estadual de Campinas (UNICAMP), SP (Brazil). Inst. de Quimica], e-mail: lhbb@iqm.unicamp.br
2009-07-01
A synthesis of (+)-{alpha}-terpineol from (+)-limonene was proposed as a project for undergraduate organic laboratory course. Terpineol is a useful flavor and fragrance compound, and several aspects of this preparation are suited for experimental organic classes, including basic techniques for extraction and analyses of essential oils, different reaction types and the possibility of a high degree of student interest. (author)
5. Using student-generated UV-induced Escherichia coli mutants in a directed inquiry undergraduate genetics laboratory.
Science.gov (United States)
Healy, Frank G; Livingstone, Kevin D
2010-09-01
We report a thematic sequence of directed inquiry-based labs taking students from bacterial mutagenesis and phenotypic identification of their own self-created mutant, through identification of mutated genes by biochemical testing, to verification of mutant alleles by complementation, and finally to mutant allele characterization by DNA sequence analysis. The lab utilizes UV mutagenesis with wild-type Escherichia coli and a UV-sensitive isogenic derivative optimized for undergraduate use. The labs take advantage of the simplicity of E. coli in a realistic genetic investigation using safe UV irradiation methods for creation and characterization of novel mutants. Assessment data collected over three offerings of the course suggest that the labs, which combine original investigation in a scientifically realistic intellectual environment with learned techniques and concepts, were instrumental in improving students' learning in a number of areas. These include the development of critical thinking skills and understanding of concepts and methods. Student responses also suggest the labs were helpful in improving students' understanding of the scientific process as a rational series of experimental investigations and awareness of the interdisciplinary nature of scientific inquiry.
6. Hands-On Experiences of Undergraduate Students in Automatics and Robotics Using a Virtual and Remote Laboratory
Science.gov (United States)
Jara, Carlos A.; Candelas, Francisco A.; Puente, Santiago T.; Torres, Fernando
2011-01-01
Automatics and Robotics subjects are always greatly improved when classroom teaching is supported by adequate laboratory courses and experiments following the "learning by doing" paradigm, which provides students a deep understanding of theoretical lessons. However, expensive equipment and limited time prevent teachers having sufficient…
7. Integration of a Faculty's Ongoing Research into an Undergraduate Laboratory Teaching Class in Developmental Biology
Science.gov (United States)
Nam, Sang-Chul
2018-01-01
Traditional developmental biology laboratory classes have utilized a number of different model organisms to allow students to be exposed to diverse biological phenomena in developing organisms. This traditional approach has mainly focused on the diverse morphological and anatomical descriptions of the developing organisms. However, modern…
8. Drug Synthesis and Analysis on a Dime: A Capstone Medicinal Chemistry Experience for the Undergraduate Biochemistry Laboratory
Science.gov (United States)
Streu, Craig N.; Reif, Randall D.; Neiles, Kelly Y.; Schech, Amanda J.; Mertz, Pamela S.
2016-01-01
Integrative, research-based experiences have shown tremendous potential as effective pedagogical approaches. Pharmaceutical development is an exciting field that draws heavily on organic chemistry and biochemistry techniques. A capstone drug synthesis/analysis laboratory is described where biochemistry students synthesize azo-stilbenoid compounds…
9. Deaf, Hard-of-Hearing, and Hearing Signing Undergraduates' Attitudes toward Science in Inquiry-Based Biology Laboratory Classes
Science.gov (United States)
Gormally, Cara
2017-01-01
For science learning to be successful, students must develop attitudes toward support future engagement with challenging social issues related to science. This is especially important for increasing participation of students from underrepresented populations. This study investigated how participation in inquiry-based biology laboratory classes…
10. Cross-Course Collaboration in the Undergraduate Chemistry Curriculum: Isotopic Labeling with Sodium Borodeuteride in the Introductory Organic Chemistry Laboratory
Science.gov (United States)
Kjonaas, Richard A.; Fitch, Richard W.; Noll, Robert J.
2017-01-01
A microscale isotopic labeling experiment is described for the introductory organic chemistry laboratory course wherein half of the students use sodium borohydride (NaBH[subscript 4]) and the other half use sodium borodeuteride (NaBD[subscript 4]) to reduce acetophenone to 1-phenylethanol and then compare spectral data. The cost is reasonable, and…
11. A Simple LIBS (Laser-Induced Breakdown Spectroscopy) Laboratory Experiment to Introduce Undergraduates to Calibration Functions and Atomic Spectroscopy
Science.gov (United States)
Chinni, Rosemarie C.
2012-01-01
This laboratory experiment introduces students to a different type of atomic spectroscopy: laser-induced breakdown spectroscopy (LIBS). LIBS uses a laser-generated spark to excite the sample; once excited, the elemental emission is spectrally resolved and detected. The students use LIBS to analyze a series of standard synthetic silicate samples…
12. Genomics and Bioinformatics in Undergraduate Curricula: Contexts for Hybrid Laboratory/Lecture Courses for Entering and Advanced Science Students
Science.gov (United States)
Temple, Louise; Cresawn, Steven G.; Monroe, Jonathan D.
2010-01-01
Emerging interest in genomics in the scientific community prompted biologists at James Madison University to create two courses at different levels to modernize the biology curriculum. The courses are hybrids of classroom and laboratory experiences. An upper level class uses raw sequence of a genome (plasmid or virus) as the subject on which to…
13. Undergraduate Student Attitudes and Perceptions toward Low- and High-Level Inquiry Exercise Physiology Teaching Laboratory Experiences
Science.gov (United States)
Henige, Kim
2011-01-01
The purpose of this investigation was to compare student attitudes toward two different science laboratory learning experiences, specifically, traditional, cookbook-style, low-inquiry level (LL) activities and a high-inquiry level (HL) investigative project. In addition, we sought to measure and compare students' science-related attitudes and…
14. Deaf, Hard-of-Hearing, and Hearing Signing Undergraduates' Attitudes toward Science in Inquiry-Based Biology Laboratory Classes.
Science.gov (United States)
Gormally, Cara
2017-01-01
15. Animal laboratory, interactive and computer based learning, in enhancing basic concepts in physiology: an outlook of 481 undergraduate medical students.
Science.gov (United States)
Shore, Najla; Khawar, Shireen; Qutab, Miraa; Ayub, Muhammad
2013-01-01
Laboratory exercises are intended to illustrate concepts and add an active learning component to courses. Since 1980s, there has been a decline in animal laboratories in medical physiology courses. Other cost-effective non-aninmal alternatives are being sought. The present study was designed to find out the students' opinion regarding the animal versus computer lab and whether innovative teaching methodologies helped students achieve their goals. Opinions of 481 female in medical students of 2nd and 3rd year MBBS were included in the study. A questionnaire based on animal/computer based experiments and new teaching methodologies in physiology was voluntarily filled in by the students. Majority of students immensely benefited from both the animal lab and other teaching methodologies. Although computer based learning is considered effective in helping students acquire basic concepts, there is evidence that some students acquire a more thorough understanding of the material through more advanced and challenging experience of an animal laboratory. The fact that such labs as well various teaching methods offer distinct educational advantages should be taken into account when courses are designed.
16. Using a PyMOL activity to reinforce the connection between genotype and phenotype in an undergraduate genetics laboratory.
Directory of Open Access Journals (Sweden)
Alexandra D Simmons
Full Text Available With the purpose of developing an activity that would help clarify genetic concepts related to the connection between genotype and phenotype and the nature of mutations, we designed a three hour teaching module using the PyMol software. The activity starts with two pre-laboratory assignments, one to learn how to use PyMol and the other to read about a specific protein or protein family. During the laboratory students are given instructions where and how to find additional information on a specific disease and its causal mutations in order to prepare a 10-minute, in-class presentation. Using a post activity, anonymous quiz, we found a statistically significant different grade distribution in students that participated in the PyMol activity relative to a control group. We also found a significant improvement in the student's comprehension when answering questions regarding the nature of mutations and protein structure. This demonstrates the utility of this simulation activity as a vehicle to improve student's understanding of specific key genetic concepts.
17. From gene to structure: Lactobacillus bulgaricus D-lactate dehydrogenase from yogurt as an integrated curriculum model for undergraduate molecular biology and biochemistry laboratory courses.
Science.gov (United States)
Lawton, Jeffrey A; Prescott, Noelle A; Lawton, Ping X
2018-03-07
We have developed an integrated, project-oriented curriculum for undergraduate molecular biology and biochemistry laboratory courses spanning two semesters that is organized around the ldhA gene from the yogurt-fermenting bacterium Lactobacillus bulgaricus, which encodes the enzyme d-lactate dehydrogenase. The molecular biology module, which consists of nine experiments carried out over eleven sessions, begins with the isolation of genomic DNA from L. bulgaricus in yogurt and guides students through the process of cloning the ldhA gene into a prokaryotic expression vector, followed by mRNA isolation and characterization of recombinant gene expression levels using RT-PCR. The biochemistry module, which consists of nine experiments carried out over eight sessions, begins with overexpression of the cloned ldhA gene and guides students through the process of affinity purification, biochemical characterization of the purified LdhA protein, and analysis of enzyme kinetics using various substrates and an inhibitor, concluding with a guided inquiry investigation of structure-function relationships in the three-dimensional structure of LdhA using molecular visualization software. Students conclude by writing a paper describing their work on the project, formatted as a manuscript to be submitted for publication in a scientific journal. Overall, this curriculum, with its emphasis on experiential learning, provides hands-on training with a variety of common laboratory techniques in molecular biology and biochemistry and builds experience with the process of scientific reasoning, along with reinforcement of essential transferrable skills such as critical thinking, information literacy, and written communication, all within the framework of an extended project having the look and feel of a research experience. © 2018 by The International Union of Biochemistry and Molecular Biology, 2018. © 2018 The International Union of Biochemistry and Molecular Biology.
18. Clays as green catalysts in the cholesterol esterification: spectroscopic characterization and polymorphs identification by thermal analysis methods. An interdisciplinary laboratorial proposal for the undergraduate level; Argilas como catalisadores verdes na esterificacao do colesterol: caracterizacao espectroscopica e identificacao de polimorfos por metodos de analise termica. Uma proposta laboratorial interdisciplinar para o primeiro ciclo universitario
Energy Technology Data Exchange (ETDEWEB)
Maria, Teresa M R.; Nunes, Rui M. D.; Pereira, Mariette M.; Eusebio, M. Ermelinda S. [Universidade de Coimbra, Coimbra (Portugal). Dept. de Quimica], e-mail: troseiro@ci.uc.pt
2009-07-01
A laboratory experiment that enables the professor to introduce the problematic of sustainable development in pharmaceutical chemistry to undergraduate students is proposed, using a simple synthetic procedure. Cholesteryl acetate is prepared by the esterification of cholesterol using Montmorillonite K10 as heterogeneous catalyst. Cholesterol and cholesteryl acetate are characterized by spectroscopic ({sup 1}H RMN, {sup 13}C RMN, FTIR) and thermal analysis techniques. The thermal methods are used to introduce the concepts of polymorphism and the nature of mesophases. (author)
19. An Undergraduate Chemistry Laboratory: Synthesis of Well-Defined Polymers by Low-Catalyst-Concentration ATRP and Postpolymerization Modification to Fluorescent Materials
Science.gov (United States)
Tsarevsky, Nicolay V.; Woodruf, Shannon R.; Wisian-Neilson, Patty J.
2016-01-01
A two-session experiment is designed to introduce undergraduate students to concepts in catalysis, transition metal complexes, polymer synthesis, and postpolymerization modifications. In the first session, students synthesize poly(glycidyl methacrylate) via low-catalyst-concentration atom transfer radical polymerization (ATRP). The…
20. Microwave-Assisted Synthesis of a Natural Insecticide on Basic Montmorillonite K10 Clay. Green Chemistry in the Undergraduate Organic Laboratory
Science.gov (United States)
Dintzner, Matthew R.; Wucka, Paul R.; Lyons, Thomas W.
2006-01-01
A detailed investigation of the clay-catalyzed condensation of sesamol and other phenols with 3-methyl-2-butenal to give methylenedioxyprecocene (MDP) and other chromenes is presented. The clay-catalyzed microwave-assisted condensation of sesamol with 3-methyl-2-butenal is appropriate for incorporation into undergraduate organic laboratory…
1. Teaching Cardiac Electrophysiology Modeling to Undergraduate Students: Laboratory Exercises and GPU Programming for the Study of Arrhythmias and Spiral Wave Dynamics
Science.gov (United States)
Bartocci, Ezio; Singh, Rupinder; von Stein, Frederick B.; Amedome, Avessie; Caceres, Alan Joseph J.; Castillo, Juan; Closser, Evan; Deards, Gabriel; Goltsev, Andriy; Ines, Roumwelle Sta.; Isbilir, Cem; Marc, Joan K.; Moore, Diquan; Pardi, Dana; Sadhu, Sandeep; Sanchez, Samuel; Sharma, Pooja; Singh, Anoopa; Rogers, Joshua; Wolinetz, Aron; Grosso-Applewhite, Terri; Zhao, Kai; Filipski, Andrew B.; Gilmour, Robert F., Jr.; Grosu, Radu; Glimm, James; Smolka, Scott A.; Cherry, Elizabeth M.; Clarke, Edmund M.; Griffeth, Nancy; Fenton, Flavio H.
2011-01-01
As part of a 3-wk intersession workshop funded by a National Science Foundation Expeditions in Computing award, 15 undergraduate students from the City University of New York collaborated on a study aimed at characterizing the voltage dynamics and arrhythmogenic behavior of cardiac cells for a broad range of physiologically relevant conditions…
2. An Investigation into the Creation, Stability, and X-Ray Fluorescence Analysis of Early Photographic Processes: An Upper-Level Undergraduate Laboratory
Science.gov (United States)
Rogge, Corina E.; Bezur, Aniko
2012-01-01
Photography is one of the few fine art forms that were initially developed by scientists such as Herschel and Talbot; however, in the modern chemistry curriculum, photography has become divorced from its scientific beginnings and resides in the studio arts department of most universities. An upper-level undergraduate experiment is described in…
3. Doing That Thing That Scientists Do: A Discovery-Driven Module on Protein Purification and Characterization for the Undergraduate Biochemistry Laboratory Classroom
Science.gov (United States)
Garrett, Teresa A.; Osmundson, Joseph; Isaacson, Marisa; Herrera, Jennifer
2015-01-01
In traditional introductory biochemistry laboratory classes students learn techniques for protein purification and analysis by following provided, established, step-by-step procedures. Students are exposed to a variety of biochemical techniques but are often not developing procedures or collecting new, original data. In this laboratory module,…
4. Using Castration Surgery in Male Rats to Demonstrate the Physiological Effects of Testosterone on Seminal Vesicle Anatomy in an Undergraduate Laboratory Setting
Science.gov (United States)
Belanger, Rachelle M.; Conant, Stephanie B.; Grabowski, Gregory M.
2013-01-01
Rats can be used as a model organism to teach physiological concepts in a laboratory setting. This article describes a two-part laboratory that introduces students to hypothesis testing, experimental design, the appropriate use of controls and surgical techniques. Students perform both a castration and sham-control surgery on male rats and test…
5. Environmental Regulation of Plant Gene Expression: An Rt-qPCR Laboratory Project for an Upper-Level Undergraduate Biochemistry or Molecular Biology Course
Science.gov (United States)
Eickelberg, Garrett J.; Fisher, Alison J.
2013-01-01
We present a novel laboratory project employing "real-time" RT-qPCR to measure the effect of environment on the expression of the "FLOWERING LOCUS C" gene, a key regulator of floral timing in "Arabidopsis thaliana" plants. The project requires four 3-hr laboratory sessions and is aimed at upper-level undergraduate…
DEFF Research Database (Denmark)
Lauritzen, Niels
Based on undergraduate teaching to students in computer science, economics and mathematics at Aarhus University, this is an elementary introduction to convex sets and convex functions with emphasis on concrete computations and examples. Starting from linear inequalities and Fourier-Motzkin elimin...
7. Purchase of Microwave Reactors for Implementation of Small-scale Microwave-accelerated Organic Chemistry Laboratory Program in Undergraduate Curriculum and Synthetic Chemistry Research at HU
Science.gov (United States)
2015-05-16
Yadav, Hemant Mande, and Prasanna Ghalsasi, Nitration of Phenols Using Cu(NO3)2: Green Chemistry Laboratory Experiment, Journal of Chemical...A Microwave-Assisted Friedel–Crafts Acylation of Toluene with Anhydrides Fehmi Damkaci, Michelle Dallas, and Megan Wagner Journal of Chemical...and Robert Kobelja Journal of Chemical Education 2008 85 (2), 261 30. Nitration of Phenols Using Cu(NO3)2: Green Chemistry Laboratory Experiment
8. The development of remote teaching laboratory access software for multi-slice computed optical tomography for use in undergraduate nuclear education
International Nuclear Information System (INIS)
Price, T.J.; Nichita, E.
2013-01-01
Internet-based laboratory exercises were developed for a course on biomedical imaging at the University of Ontario Institute of Technology. These exercises used a multi-slice computed optical tomography machine named DeskCAT to instruct students on the principals of computed tomography. User management software was developed which enabled course instructors to quickly set up a computer to accept a series of scheduled remote user connections for a classroom. Laboratory exercises using the DeskCAT machine were developed to be conducted remotely. (author)
9. Participation in a Year-Long CURE Embedded into Major Core Genetics and Cellular and Molecular Biology Laboratory Courses Results in Gains in Foundational Biological Concepts and Experimental Design Skills by Novice Undergraduate Researchers
Directory of Open Access Journals (Sweden)
Marcy A. Peteroy-Kelly
2017-05-01
Full Text Available This two-year study describes the assessment of student learning gains arising from participation in a year-long curriculum consisting of a classroom undergraduate research experience (CURE embedded into second-year, major core Genetics and Cellular and Molecular Biology (CMB laboratory courses. For the first course in our CURE, students used micro-array or RNAseq analyses to identify genes important for environmental stress responses by Saccharomyces cerevisiae. The students were tasked with creating overexpressing mutants of their genes and designing their own original experiments to investigate the functions of those genes using the overexpression and null mutants in the second CURE course. In order to evaluate student learning gains, we employed three validated concept inventories in a pretest/posttest format and compared gains on the posttest versus the pretest with student laboratory final grades. Our results demonstrated that there was a significant correlation between students earning lower grades in the Genetics laboratory for both years of this study and gains on the Genetics Concept Assessment (GCA. We also demonstrated a correlation between students earning lower grades in the Genetics laboratory and gains on the Introductory Molecular and Cell Biology Assessment (IMCA for year 1 of the study. Students furthermore demonstrated significant gains in identifying the variable properties of experimental subjects when assessed using the Rubric for Experimental (RED design tool. Results from the administration of the CURE survey support these findings. Our results suggest that a year-long CURE enables lower performing students to experience greater gains in their foundational skills for success in the STEM disciplines.
DEFF Research Database (Denmark)
Lauritzen, Niels
Based on undergraduate teaching to students in computer science, economics and mathematics at Aarhus University, this is an elementary introduction to convex sets and convex functions with emphasis on concrete computations and examples. Starting from linear inequalities and Fourier-Motzkin elimin......Based on undergraduate teaching to students in computer science, economics and mathematics at Aarhus University, this is an elementary introduction to convex sets and convex functions with emphasis on concrete computations and examples. Starting from linear inequalities and Fourier......-Motzkin elimination, the theory is developed by introducing polyhedra, the double description method and the simplex algorithm, closed convex subsets, convex functions of one and several variables ending with a chapter on convex optimization with the Karush-Kuhn-Tucker conditions, duality and an interior point...... algorithm....
11. Cross-Course Collaboration in the Undergraduate Chemistry Curriculum: Primary Kinetic Isotope Effect in the Hypochlorite Oxidation of 1-Phenylethanol in the Physical Chemistry Laboratory
Science.gov (United States)
Noll, Robert J.; Fitch, Richard W.; Kjonaas, Richard A.; Wyatt, Richard A.
2017-01-01
A kinetic isotope effect (KIE) experiment is described for the physical chemistry laboratory. Students conduct a hypochlorite (household bleach) oxidation of an equimolar mixture of 1-phenylethanol and 1-deuterio-1-phenylethanol to acetophenone. The reaction occurs in a biphasic reaction mixture and follows first-order kinetics with respect to…
12. Spectrophotometric Determination of 6-Propyl-2-Thiouracil in Pharmaceutical Formulations Based on Prussian Blue Complex Formation: An Undergraduate Instrumental Analysis Laboratory Experiment
Science.gov (United States)
Zakrzewski, Robert; Skowron, Monika; Ciesielski, Witold; Rembisz, Zaneta
2016-01-01
The laboratory experiment challenges students to determine 6-propyl-2-thiouracil (PTU) based on Prussian blue complex formation. Prussian blue is formed by ferricyanide and Fe(II) ions which are generated in situ from Fe(III) ions reduced by PTU. The absorbance of this product was measured at a wavelength of 840 nm, after a reaction time of 30…
13. What Is the True Color of Fresh Meat? A Biophysical Undergraduate Laboratory Experiment Investigating the Effects of Ligand Binding on Myoglobin Using Optical, EPR, and NMR Spectroscopy
Science.gov (United States)
Linenberger, Kimberly; Bretz, Stacey Lowery; Crowder, Michael W.; McCarrick, Robert; Lorigan, Gary A.; Tierney, David L.
2011-01-01
With an increased focus on integrated upper-level laboratories, we present an experiment integrating concepts from inorganic, biological, and physical chemistry content areas. Students investigate the effects of ligand strength on the spectroscopic properties of the heme center in myoglobin using UV-vis, [superscript 1]H NMR, and EPR…
14. [superscript 1]H NMR Spectroscopy-Based Configurational Analysis of Mono- and Disaccharides and Detection of ß-Glucosidase Activity: An Undergraduate Biochemistry Laboratory
Science.gov (United States)
Periyannan, Gopal R.; Lawrence, Barbara A.; Egan, Annie E.
2015-01-01
A [superscript 1]H NMR spectroscopy-based laboratory experiment explores mono- and disaccharide structural chemistry, and the enzyme-substrate specificity of glycosidic bond cleavage by ß-glucosidase towards cellobiose (ß-linked gluco-disaccharide) and maltose (a-linked gluco-disaccharide). Structural differences between cellobiose, maltose, and…
15. Introducing Education for Sustainable Development in the Undergraduate Laboratory: Quantitative Analysis of Bioethanol Fuel and Its Blends with Gasoline by Using Solvatochromic Dyes
Science.gov (United States)
Galgano, Paula D.; Loffredo, Carina; Sato, Bruno M.; Reichardt, Christian; El Seoud, Omar A.
2012-01-01
The concept of "Education for Sustainable Development", ESD, has been introduced in a period where chemistry education is undergoing a major change, both in emphasis and methods of teaching. Studying an everyday problem, with an important socio-economic impact in the laboratory is a part of this approach. Presently, the students in many…
16. Using a Molecular-Genetic Approach to Investigate Bacterial Physiology in a Continuous, Research-Based, Semester-Long Laboratory for Undergraduates
Directory of Open Access Journals (Sweden)
Jeremiah Foster Ault
2011-09-01
Full Text Available Designing investigative laboratory exercises that encourage critical thinking, problem solving, and independent thought for upper-division biology courses is a difficult but worthwhile task. In an effort to do so, we developed a semester-long, continuous, research-based investigative laboratory that integrates numerous genetic and molecular biology methods into the investigation of a bacterial physiological process. In this lab, students use random Tn5 transposon mutagenesis to create prodigiosin pigment mutants in the bacterium, Serratia marcescens. This is followed by phenotypic characterization, cloning, and sequencing the Tn insertion site to identify genes involved in pigment biosynthesis. During this lab, students gain ample experience performing basic lab techniques while learning about — and applying — methods for elucidating gene function. The approach to the laboratory and the outcomes are intimately integrated into the teaching of many fundamental physiological processes underlying prodigiosin production in bacteria. The result is a cohesive course that integrates the theory and application of molecular genetic techniques with the study of bacterial physiology. Assessments of student learning objectives demonstrated that students greatly improved their understanding of both physiological processes and the genetic techniques used to investigate them. In addition, students felt that this semester-long exercise provided the necessary laboratory experience they needed and desired in preparation for careers in molecular biology, microbiology, and biochemistry.
17. Determination of Mercury in Fish: A Low-Cost Implementation of Cold-Vapor Atomic Absorbance for the Undergraduate Environmental Chemistry Laboratory
Science.gov (United States)
Niece, Brian K.; Hauri, James F.
2013-01-01
Mercury is a known neurotoxin that is particularly harmful to children and unborn fetuses. Consumption of contaminated fish is one major route of mercury exposure. This laboratory experiment gives students an opportunity to measure mercury concentrations in store-bought seafood and compare the results to suggested exposure limits. The U.S.…
18. An Undergraduate Investigation into the 10-23 DNA Enzyme that Cleaves RNA: DNA Can Cut It in the Biochemistry Laboratory
Science.gov (United States)
Flynn-Charlebois, Amber; Burns, Jamie; Chapelliquen, Stephanie; Sanmartino, Holly
2011-01-01
A low-cost biochemistry experiment is described that demonstrates current techniques in the use of catalytic DNA molecules and introduces a nonradioactive, nonfluorescent, inexpensive, fast, and safe method for monitoring these nucleic acid reactions. The laboratory involves the exploration of the 10-23 DNA enzyme as it cleaves a specific RNA…
19. Synthesis of a Self-Healing Polymer Based on Reversible Diels-Alder Reaction: An Advanced Undergraduate Laboratory at the Interface of Organic Chemistry and Materials Science
Science.gov (United States)
Weizman, Haim; Nielsen, Christian; Weizman, Or S.; Nemat-Nasser, Sia
2011-01-01
This laboratory experiment exposes students to the chemistry of self-healing polymers based on a Diels-Alder reaction. Students accomplish a multistep synthesis of a monomer building block and then polymerize it to form a cross-linked polymer. The healing capability of the polymer is verified by differential scanning calorimetry (DSC) experiments.…
20. A One-Pot Self-Assembly Reaction to Prepare a Supramolecular Palladium(II) Cyclometalated Complex: An Undergraduate Organometallic Laboratory Experiment
Science.gov (United States)
Fernandez, Alberto; Lopez-Torres, Margarita; Fernandez, Jesus J.; Vazquez-Garcia, Digna; Vila, Jose M.
2012-01-01
A laboratory experiment for students in advanced inorganic chemistry is described. Students prepare palladium(II) cyclometalated complexes. A terdentate [C,N,O] Schiff base ligand is doubly deprotonated upon reaction with palladium(II) acetate in a self-assembly process to give a palladacycle with a characteristic tetranuclear structure. This…
1. Doing that thing that scientists do: A discovery-driven module on protein purification and characterization for the undergraduate biochemistry laboratory classroom.
Science.gov (United States)
Garrett, Teresa A; Osmundson, Joseph; Isaacson, Marisa; Herrera, Jennifer
2015-01-01
In traditional introductory biochemistry laboratory classes students learn techniques for protein purification and analysis by following provided, established, step-by-step procedures. Students are exposed to a variety of biochemical techniques but are often not developing procedures or collecting new, original data. In this laboratory module, students develop research skills through work on an original research project and gain confidence in their ability to design and execute an experiment while faculty can enhance their scholarly pursuits through the acquisition of original data in the classroom laboratory. Students are prepared for a 6-8 week discovery-driven project on the purification of the Escherichia coli cytidylate kinase (CMP kinase) through in class problems and other laboratory exercises on bioinformatics and protein structure analysis. After a minimal amount of guidance on how to perform the CMP kinase in vitro enzyme assay, SDS-PAGE, and the basics of protein purification, students, working in groups of three to four, develop a protein purification protocol based on the scientific literature and investigate some aspect of CMP kinase that interests them. Through this process, students learn how to implement a new but perhaps previously worked out procedure to answer their research question. In addition, they learn the importance of keeping a clear and thorough laboratory notebook and how to interpret their data and use that data to inform the next set of experiments. Following this module, students had increased confidence in their ability to do basic biochemistry techniques and reported that the "self-directed" nature of this lab increased their engagement in the project. © 2015 The International Union of Biochemistry and Molecular Biology.
2. Quantum optics and nano-optics teaching laboratory for the undergraduate curriculum: teaching quantum mechanics and nano-physics with photon counting instrumentation
Science.gov (United States)
Lukishova, Svetlana G.
2017-08-01
At the Institute of Optics, University of Rochester (UR), we have adapted to the main challenge (the lack of space in the curriculum) by developing a series of modular 3-hour experiments and 20-min-demonstrations based on technical elective, 4-credit-hour laboratory course "Quantum Optics and Nano-Optics Laboratory" (OPT 253/OPT453/PHY434), that were incorporated into a number of required courses ranging from freshman to senior level. Rochester Monroe Community College (MCC) students also benefited from this facility that was supported by four NSF grants. MCC students carried out two 3-hour labs on photon quantum mechanics at the UR. Since 2006, total 566 students passed through the labs with lab reports submission (including 144 MCC students) and more than 250 students through lab demonstrations. In basic class OPT 253, four teaching labs were prepared on generation and characterization of entangled and single (antibunched) photons demonstrating the laws of quantum mechanics: (1) entanglement and Bell's inequalities, (2) single-photon interference (Young's double slit experiment and Mach-Zehnder interferometer), (3) confocal microscope imaging of single-emitter (colloidal nanocrystal quantum dots and NV-center nanodiamonds) fluorescence within photonic (liquid crystal photonic bandgap microcavities) or plasmonic (gold bowtie nanoantennas) nanostructures, (4) Hanbury Brown and Twiss setup. Fluorescence antibunching from nanoemitters. Students also carried out measurements of nanodiamond topography using atomic force microscopy and prepared photonic bandgap materials from cholesteric liquid crystals. Manuals, student reports, presentations, lecture materials and quizzes, as well as some NSF grants' reports are placed on a website http://www.optics.rochester.edu/workgroups/lukishova/QuantumOpticsLab/ . In 2011 UR hosted 6 professors from different US universities in three-days training of these experiments participating in the Immersion Program of the Advanced
3. Thermo-fluid dynamics of two-phase flow
CERN Document Server
Ishii, Mamoru; Ishii, Mamoru; Ishii, M
2006-01-01
Provides a very systematic treatment of two phase flow problems from a theoretical perspectiveProvides an easy to follow treatment of modeling and code devlopemnt of two phase flow related phenomenaCovers new results of two phase flow research such as coverage of fuel cells technology.
4. Thermo-fluid dynamic analysis of wet compression process
Energy Technology Data Exchange (ETDEWEB)
Mohan, Abhay; Kim, Heuy Dong [School of Mechanical Engineering, Andong National University, Andong (Korea, Republic of); Chidambaram, Palani Kumar [FMTRC, Daejoo Machinery Co. Ltd., Daegu (Korea, Republic of); Suryan, Abhilash [Dept. of Mechanical Engineering, College of Engineering Trivandrum, Kerala (India)
2016-12-15
Wet compression systems increase the useful power output of a gas turbine by reducing the compressor work through the reduction of air temperature inside the compressor. The actual wet compression process differs from the conventional single phase compression process due to the presence of latent heat component being absorbed by the evaporating water droplets. Thus the wet compression process cannot be assumed isentropic. In the current investigation, the gas-liquid two phase has been modeled as air containing dispersed water droplets inside a simple cylinder-piston system. The piston moves in the axial direction inside the cylinder to achieve wet compression. Effects on the thermodynamic properties such as temperature, pressure and relative humidity are investigated in detail for different parameters such as compression speeds and overspray. An analytical model is derived and the requisite thermodynamic curves are generated. The deviations of generated thermodynamic curves from the dry isentropic curves (PV{sup γ} = constant) are analyzed.
5. Thermo-fluid dynamic analysis of wet compression process
International Nuclear Information System (INIS)
Mohan, Abhay; Kim, Heuy Dong; Chidambaram, Palani Kumar; Suryan, Abhilash
2016-01-01
Wet compression systems increase the useful power output of a gas turbine by reducing the compressor work through the reduction of air temperature inside the compressor. The actual wet compression process differs from the conventional single phase compression process due to the presence of latent heat component being absorbed by the evaporating water droplets. Thus the wet compression process cannot be assumed isentropic. In the current investigation, the gas-liquid two phase has been modeled as air containing dispersed water droplets inside a simple cylinder-piston system. The piston moves in the axial direction inside the cylinder to achieve wet compression. Effects on the thermodynamic properties such as temperature, pressure and relative humidity are investigated in detail for different parameters such as compression speeds and overspray. An analytical model is derived and the requisite thermodynamic curves are generated. The deviations of generated thermodynamic curves from the dry isentropic curves (PV γ = constant) are analyzed
Directory of Open Access Journals (Sweden)
Marília Mendes Ferreira
2016-09-01
Directory of Open Access Journals (Sweden)
Marília Mendes Ferreira
2016-09-01
8. Argilas como catalisadores verdes na esterificação do colesterol: caracterização espectroscópica e identificação de polimorfos por métodos de análise térmica. Uma proposta laboratorial interdisciplinar para o 1º ciclo universitário Clays as green catalysts in the cholesterol esterification: spectroscopic characterization and polymorphs identification by thermal analysis methods. An interdisciplinary laboratorial proposal for the undergraduate level
Directory of Open Access Journals (Sweden)
Teresa M. R. Maria
2009-01-01
Full Text Available A laboratory experiment that enables the professor to introduce the problematic of sustainable development in pharmaceutical chemistry to undergraduate students is proposed, using a simple synthetic procedure. Cholesteryl acetate is prepared by the esterification of cholesterol using Montmorillonite K10 as heterogeneous catalyst. Cholesterol and cholesteryl acetate are characterized by spectroscopic (¹H RMN, 13C RMN, FTIR and thermal analysis techniques. The thermal methods are used to introduce the concepts of polymorphism and the nature of mesophases.
9. Innovation of Undergraduate Medical Education
OpenAIRE
植村, 研一; Uemura, Kenichi
1995-01-01
Classical undergraduate medical education in Japan has largely based on didactic lectures, followed by protocol-guided laboratory experiments and clinical training of history taking and physical examination. Such education strategies are efficient for cramming facts and theories, which will soon become obsolete by the time when the students go into clinical practice and are not effective for education of effective clinical skills. In the cognitive domain, what students must learn are not fact...
10. 20th Annual ASM Conference for Undergraduate Educators (ASMCUE)
OpenAIRE
Michelle Slone
2013-01-01
Delaware Technical Community College (DTCC) is one of the pilot schools involved in the Community College Undergraduate Research Initiative (CCURI) which is responding to the call for reform of undergraduate science education. The major tenet of this initiative is to engage students early in their course of study by embedding undergraduate research into the curriculum. At DTCC this is accomplished by incorporating research-based laboratories, case studies, and problem-based learning activitie...
11. Cosmic collaboration in an undergraduate astrophysics laboratory
Science.gov (United States)
Gunter, Ramona; Spiczak, Glenn; Madsen, James
2010-10-01
Lessons learned during the first offering of a lab component of an intermediate astrophysics course at the University of Wisconsin-River Falls are discussed. The course enrolled students from a variety of majors. Students worked in mixed-gender, mixed-major collaborative groups. They explored cosmic rays through hands-on, inquiry-based activities that took them from classic, fundamental discoveries to open-ended questions of their own design. We find that students divided their labor and brought the various parts of their research project together with little or no discussion regarding the various pieces and how they inform each other. Aspects of the lab design helped disrupt some typical gender dynamics in that men did not dominate group discussions. However, men did dominate the hands-on activities of the lab.
12. DNA Sequencing in Undergraduate Laboratory Courses.
Science.gov (United States)
Hamilton, Robert G.
1997-01-01
Discusses strategies to duplicate current research protocols using biochemical methods of analysis. Describes the use of the Silver Sequence kit that provides a technically simple and relatively inexpensive DNA sequencing exercise. (JRH)
Science.gov (United States)
Hoskins, Betty B.; Shannon, Thomas A.
1977-01-01
Discusses the importance of developing bioethics programs for undergraduate students. Two aspects are considered: (1) current areas of concern and sources of bibliographic information; and (2) problems encountered in undergraduate projects. A list of references is provided. (HM)
Science.gov (United States)
Gajwani, Kiran; Miron, Jeffrey
2015-01-01
Siegfried and Stock (2007) explore the undergraduate training of PhD economists. Their findings show that among U.S. undergraduate economics programs, the Harvard University Economics Department produces many eventual economics PhD recipients. In this article, the authors discuss Harvard's undergraduate economics program and highlight some key…
15. Toward a Conceptual Framework for Measuring the Effectiveness of Course-Based Undergraduate Research Experiences in Undergraduate Biology
Science.gov (United States)
Brownell, Sara E.; Kloser, Matthew J.
2015-01-01
Recent calls for reform have advocated for extensive changes to undergraduate science lab experiences, namely providing more authentic research experiences for students. Course-based Undergraduate Research Experiences (CUREs) have attempted to eschew the limitations of traditional "cookbook" laboratory exercises and have received…
16. Journal of Undergraduate Research, Volume IX, 2009
Energy Technology Data Exchange (ETDEWEB)
Stiner, K. S.; Graham, S.; Khan, M.; Dilks, J.; Mayer, D.
2009-01-01
Each year more than 600 undergraduate students are awarded paid internships at the Department of Energy’s (DOE) National Laboratories. Th ese interns are paired with research scientists who serve as mentors in authentic research projects. All participants write a research abstract and present at a poster session and/or complete a fulllength research paper. Abstracts and selected papers from our 2007–2008 interns that represent the breadth and depth of undergraduate research performed each year at our National Laboratories are published here in the Journal of Undergraduate Research. The fields in which these students worked included: Biology; Chemistry; Computer Science; Engineering; Environmental Science; General Science; Materials Science; Medical and Health Sciences; Nuclear Science; Physics; Science Policy; and Waste Management.
17. Green Building Research Laboratory
Energy Technology Data Exchange (ETDEWEB)
Sailor, David Jean [Portland State Univ., Portland, OR (United States)
2013-12-29
This project provided support to the Green Building Research Laboratory at Portland State University (PSU) so it could work with researchers and industry to solve technical problems for the benefit of the green building industry. It also helped to facilitate the development of PSU’s undergraduate and graduate-level training in building science across the curriculum.
18. Heat Exchanger Lab for Chemical Engineering Undergraduates
Science.gov (United States)
Rajala, Jonathan W.; Evans, Edward A.; Chase, George G.
2015-01-01
Third year chemical engineering undergraduate students at The University of Akron designed and fabricated a heat exchanger for a stirred tank as part of a Chemical Engineering Laboratory course. The heat exchanger portion of this course was three weeks of the fifteen week long semester. Students applied concepts of scale-up and dimensional…
19. Metabolic Syndrome among Undergraduate Students Attending ...
African Journals Online (AJOL)
1Laboratory Department, College of Applied Medical Sciences, 2Department of Community Medicine - College of Medicine, ... undergraduate students in three Sudanese universities. Methods: A total of 384 first-year ... Keywords: Metabolic syndrome, Obesity, Hypertension, Diabetes, Dyslipidemia, Anthropometric. Tropical ...
20. Centrifugal Pump Experiment for Chemical Engineering Undergraduates
Science.gov (United States)
Vanderslice, Nicholas; Oberto, Richard; Marrero, Thomas R.
2012-01-01
The purpose of this paper is to describe a Centrifugal Pump Experiment that provided an experiential learning experience to chemical engineering undergraduates at the University of Missouri in the spring of 2010 in the Unit Operations Laboratory course. Lab equipment was used by senior students with computer-based data and control technology. In…
1. Incorporating Safety into a Unit Operations Laboratory Course.
Science.gov (United States)
King, Julia A.
1998-01-01
Details the incorporation of safety procedures and issues into the curriculum of an undergraduate chemical engineering unit operations laboratory course. Includes checklists and sample reporting forms. (DDR)
2. Electrochemistry "Discovery" Course for Undergraduates
Science.gov (United States)
May, Michael Alan; Gupta, Vijay K.
1997-07-01
We developed a chemistry selected topics course at Central State University, "Introduction to Laboratory Techniques in Electrochemistry" to: (1) give undergraduates hands-on experience with electrochemical measurements, (2) prepare students for summer research in Fuel Cell and Battery technology. Since students "learn by doing", the course is suitable for undergraduates from sophomore to senior levels. Students complete 6 laboratories, based on a "less is more" philosophy which emphasizes analytic and creative process rather than mandatory topical coverage. Eight electrochemical experiments are available: Construction of Zinc-Copper battery stacks, Lead Acid Battery discharge-charge cycles, Conductimetric titration of aspirin with Ammonium Hydroxide, Ion Selective Electrode determination of Fluoride in water, Cyclic Voltammetry of Potassium Ferricyanide solution, Cyclic Voltammetry of Sulfuric acid on Platinum working electrode, Anodic Stripping Voltammetry of Lead ion in solution, Differential Pulse Polarography of Lead ion in solution. Topics discussed in lecture include: chemical definitions, electrical definitions, Oxidation-Reduction reactions, Electrochemical series, Electrodes, Electrochemical Cells, direct Coulometry, electrolysis, electrochemical process efficiency, equilibrium Potentiometry, real Cell Voltages, Ion Selective Electrode types and designs, reference electrode designs, working electrode materials, pH buffers, Cyclic Voltammetry, Anodic Stripping Voltammetry, Polarography, differential pulse Polarography, and simple electrochemical instrumentation circuits.
3. Accreditation standards for undergraduate forensic science programs
Science.gov (United States)
Miller, Marilyn Tebbs
Undergraduate forensic science programs are experiencing unprecedented growth in numbers of programs offered and, as a result, student enrollments are increasing. Currently, however, these programs are not subject to professional specialized accreditation. This study sought to identify desirable student outcome measures for undergraduate forensic science programs that should be incorporated into such an accreditation process. To determine desirable student outcomes, three types of data were collected and analyzed. All the existing undergraduate forensic science programs in the United States were examined with regard to the input measures of degree requirements and curriculum content, and for the output measures of mission statements and student competencies. Accreditation procedures and guidelines for three other science-based disciplines, computer science, dietetics, and nursing, were examined to provide guidance on accreditation processes for forensic science education programs. Expert opinion on outcomes for program graduates was solicited from the major stakeholders of undergraduate forensic science programs-forensic science educators, crime laboratory directors, and recent graduates. Opinions were gathered by using a structured Internet-based survey; the total response rate was 48%. Examination of the existing undergraduate forensic science programs revealed that these programs do not use outcome measures. Of the accreditation processes for other science-based programs, nursing education provided the best model for forensic science education, due primarily to the balance between the generality and the specificity of the outcome measures. From the analysis of the questionnaire data, preliminary student outcomes, both general and discipline-specific, suitable for use in the accreditation of undergraduate forensic science programs were determined. The preliminary results were reviewed by a panel of experts and, based on their recommendations, the outcomes
African Journals Online (AJOL)
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Computer and internet has omputer and internet has omputer and internet has brought innovative chang brought innovative chang computer and IT related courses have recently been i level. Therefore, level. Therefore, it was important to know the perc it was important to know the perc undergraduate students about the.
5. Bringing Nuclear Science into the Undergraduate Curriculum
Science.gov (United States)
Peaslee, Graham
2006-04-01
6. Open Innovation Labs for Physics Undergraduate Independent Research
Science.gov (United States)
Carlsmith, Duncan
2014-03-01
The open undergraduate laboratory Garage Physics at the University of Wisconsin-Madison is home to a variety of independent physics and multidisciplinary research projects. Its maker-style environment encourages innovation and entrepreneurship. Experience establishing and staffing the laboratory will be described.
7. An Introductory Undergraduate Course Covering Animal Cell Culture Techniques
Science.gov (United States)
Mozdziak, Paul E.; Petitte, James N.; Carson, Susan D.
2004-01-01
Animal cell culture is a core laboratory technique in many molecular biology, developmental biology, and biotechnology laboratories. Cell culture is a relatively old technique that has been sparingly taught at the undergraduate level. The traditional methodology for acquiring cell culture training has been through trial and error, instruction when…
8. Communication, Communication, Communication! Growth through Laboratory Instructing
Science.gov (United States)
Peterson, Jamie J.; DeAngelo, Samantha; Mack, Nancy; Thompson, Claudia; Cooper, Jennifer; Sesma, Arturo, Jr.
2014-01-01
This study examined gains undergraduate students made in their communication and collaboration skills when they served as peer teachers, i.e., laboratory instructors (LIs), for a General Psychology laboratory. Self-ratings of communication and collaboration skills were completed before and after teaching the laboratory. When compared to before the…
9. 10 CFR 26.155 - Laboratory personnel.
Science.gov (United States)
2010-01-01
... clinical laboratory toxicology; or (ii) A PhD in one of the natural sciences with an adequate undergraduate... 10 Energy 1 2010-01-01 2010-01-01 false Laboratory personnel. 26.155 Section 26.155 Energy NUCLEAR REGULATORY COMMISSION FITNESS FOR DUTY PROGRAMS Laboratories Certified by the Department of Health and Human...
Home; Journals; Resonance – Journal of Science Education; Volume 3; Issue 12. SPIC Undergraduate Programme. P K Subrahmanyam. Information and Announcements Volume 3 Issue 12 December 1998 pp 108-110. Fulltext. Click here to view fulltext PDF. Permanent link:
11. Journal of Undergraduate Research, Volume I, 2001
Energy Technology Data Exchange (ETDEWEB)
Faletra, P.; Beavis, W.; Franz, K.; Musick, C.; Walbridge, S.E.; Myron, H.
2001-01-01
This is our first volume of the Undergraduate Journal. It is an approbation of the impressive research performed by summer interns under the guidance of their dedicated mentors. The full-length publications were chosen from a pool of submissions that were reviewed by many of the excellent scientists at our National Laboratories. Most of these students will pursue careers in science, engineering and technology and, hopefully, some of this talent will remain with our labs. We have also included about 125 abstracts that survived the review process. These were submitted from all of our participating National Laboratories.
12. Development and integration of modern laboratories in aerospace education
Science.gov (United States)
Desautel, D.; Hunter, N.; Mourtos, N.; Pernicka, H.
1992-01-01
This paper describes the development and integration of a suite of laboratories in an aerospace engineering program. The program's approach to undergraduate education is described as the source for the development of the supporting laboratories. Nine laboratories supporting instruction were developed and installed. The nine laboratories include most major flight-vehicle disciplines. The purpose and major equipments/experiments of each laboratory are briefly described, as is the integration of the laboratory with coursework. The laboratory education provided by this program successfully achieves its purpose of producing competitive aerospace engineering graduates and advancing the level of undergraduate education.
Science.gov (United States)
1997-12-01
The Council on Undergraduate Research promotes and assists development of collaborative student/faculty research at primarily undergraduate colleges and universities. Most science educators today accept such research as a critical component of an undergraduate science education. Research provides the primary opportunity for students to engage in the practice of science. We can draw an analogy between sports training and the education of young scientists. We cannot train future tennis players exclusively by providing them with lectures on tennis and supervising them performing skill-development drills. To become skilled at their game, tennis players must engage in active competition. Similarly, young scientists must engage in the enterprise that affords our understanding of the physical universe. Only by participating in scientific investigation can students understand the nature of science and become scientists.
Science.gov (United States)
Betsock, Lori
2008-08-01
15. An Undergraduate Laboratory Experiment for Upper-Level Forensic Science, Biochemistry, or Molecular Biology Courses: Human DNA Amplification Using STR Single Locus Primers by Real-Time PCR with SYBR Green Detection
Science.gov (United States)
Elkins, Kelly M.; Kadunc, Raelynn E.
2012-01-01
In this laboratory experiment, real-time polymerase chain reaction (real-time PCR) was conducted using published human TPOX single-locus DNA primers for validation and various student-designed short tandem repeat (STR) primers for Combined DNA Index System (CODIS) loci. SYBR Green was used to detect the amplification of the expected amplicons. The…
16. Conducting Mathematical Research with Undergraduates
Science.gov (United States)
Roberts, Gareth E.
2013-01-01
The notion that undergraduates are capable of making profound and original contributions to mathematical research is rapidly gaining acceptance. Undergraduates bring their enthusiasm, creativity, curiosity, and perseverance to bona fide research problems. This article discusses some of the key issues concerning undergraduate mathematical research:…
17. A Safer and Convenient Synthesis of Sulfathiazole for Undergraduate Organic and Medicinal Chemistry Classes
Science.gov (United States)
Boyle, Jeff; Otty, Sandra; Sarojini, Vijayalekshmi
2012-01-01
A safer method for the synthesis of the sulfonamide drug sulfathiazole, for undergraduate classes, is described. This method improves upon procedures currently followed in several undergraduate teaching laboratories for the synthesis of sulfathiazole. Key features of this procedure include the total exclusion of pyridine, which has potential…
18. Engaging Undergraduates in Social Science Research: The Taking the Pulse of Saskatchewan Project
Science.gov (United States)
Berdahl, Loleen
2014-01-01
Although student involvement in research and inquiry can advance undergraduate learning, there are limited opportunities for undergraduate students to be directly involved in social science research. Social science faculty members typically work outside of laboratory settings, with the limited research assistance work being completed by graduate…
19. Promoting Chemistry Learning through Undergraduate Work Experience in the Chemistry Lab: A Practical Approach
Science.gov (United States)
Yu, Hong-Bin
2015-01-01
Hiring undergraduate lab assistants in chemistry departments is common in college. However, few studies have focused on promoting undergraduate chemistry learning and thinking skills through this work experience in chemistry teaching laboratories. This article discusses the strategy we implemented in the lab assistant program. The…
20. The Effect of Guided-Inquiry Laboratory Experiments on Science Education Students' Chemistry Laboratory Attitudes, Anxiety and Achievement
Science.gov (United States)
Ural, Evrim
2016-01-01
The study aims to search the effect of guided inquiry laboratory experiments on students' attitudes towards chemistry laboratory, chemistry laboratory anxiety and their academic achievement in the laboratory. The study has been carried out with 37 third-year, undergraduate science education students, as a part of their Science Education Laboratory…
1. Bioassay Laboratory
Data.gov (United States)
Federal Laboratory Consortium — The Bioassay Laboratory is an accredited laboratory capable of conducting standardized and innovative environmental testing in the area of aquatic ecotoxicology. The...
2. HYDROMECHANICS LABORATORY
Data.gov (United States)
Federal Laboratory Consortium — Naval Academy Hydromechanics LaboratoryThe Naval Academy Hydromechanics Laboratory (NAHL) began operations in Rickover Hall in September 1976. The primary purpose of...
3. A Kinetic Experiment for the Biochemistry Laboratory.
Science.gov (United States)
Palmer, Richard E.
1986-01-01
Discusses the use of specific reactions of metabolic pathways to make measurements in the laboratory. Describes an adaptation of an experiment used in undergraduate biochemistry laboratories involving the induction of an enzyme in E. coli, as well as its partial purification and characterization. (TW)
4. Towards the Development of Phospholipid-Encapsulated Gold Nanorod Chains for Enhanced Raman-Scattering and the Improvement of Student Scientific Communication Skills in Undergraduate Classroom and Laboratory Settings
Science.gov (United States)
Stewart, Alexander F.
Depending on functionalization, nanospecies can serve effectively as Surface Enhanced Raman Scattering (SERS) probes. Their efficacy can be improved by tuning their shape and concentrating their electric field profile into smaller regions. This tuning is seen particularly well in nanorods, which concentrate such fields near the rod tips or ends, in 'hotspots'. These hotspots can be constructively enhanced through the self-assembly of the nanospecies in question, further increasing the enhancement of Raman-active species within. When considering their potential application as SERS probes, both the separation of end-to-end assembled nanorods (gap size), as well as the degree of assembly (chain length), are factors that must be optimized to obtain maximal signal. This thesis reports on the development of robust and variable methods for assembling gold nanorod species in an end-to-end configuration, and for investigating their effectiveness as SERS probes. Using both polymers and short charged ligands with control over their locations of attachment to gold nanorods, nanorod assembly could be initiated in a longitudinal direction either through changing the solvent system or through the introduction of bridging ligands. Exploitation of the inter-rod gap 'hotspot' region allowed for significant Raman enhancement of species located in said gap. Using phospholipids to encapsulate the assembling nanorod allowed for significant control over the proportions of species, in terms of length of the nanorod chain. This control allowed for further optimization of the Raman signals from species of interest. This thesis also details the investigation, over a period of several academic years, of the success of the Writing Instruction and Training (WIT) program, an initiative to iteratively improve student written communication skills as they related to scientific chemical communication. In courses ranging from first to third year, undergraduates were provided with opportunities to
5. A Two-Week Guided Inquiry Protein Separation and Detection Experiment for Undergraduate Biochemistry
Science.gov (United States)
Carolan, James P.; Nolta, Kathleen V.
2016-01-01
A laboratory experiment for teaching protein separation and detection in an undergraduate biochemistry laboratory course is described. This experiment, performed in two, 4 h laboratory periods, incorporates guided inquiry principles to introduce students to the concepts behind and difficulties of protein purification. After using size-exclusion…
6. A Methods-Based Biotechnology Course for Undergraduates
Science.gov (United States)
Chakrabarti, Debopam
2009-01-01
This new course in biotechnology for upper division undergraduates provides a comprehensive overview of the process of drug discovery that is relevant to biopharmaceutical industry. The laboratory exercises train students in both cell-free and cell-based assays. Oral presentations by the students delve into recent progress in drug discovery.…
7. Introducing Undergraduate Students to Real-Time PCR
Science.gov (United States)
Hancock, Dale; Funnell, Alister; Jack, Briony; Johnston, Jill
2010-01-01
An experiment is conducted, which in four 3 h laboratory sessions, introduces third year undergraduate Biochemistry students to the technique of real-time PCR in a biological context. The model used is a murine erythroleukemia cell line (MEL cells). These continuously cycling, immature red blood cells, arrested at an early stage in erythropoiesis,…
8. A Biosafety Level 2 Virology Lab for Biotechnology Undergraduates
Science.gov (United States)
Matza-Porges, Sigal; Nathan, Dafna
2017-01-01
Medical, industrial, and basic research relies heavily on the use of viruses and vectors. Therefore, it is important that bioscience undergraduates learn the practicalities of handling viruses. Teaching practical virology in a student laboratory setup presents safety challenges, however. The aim of this article is to describe the design and…
Science.gov (United States)
Betsock, Lori
2008-03-01
Undergraduate chemical science students—join us in New Orleans on April 6-7, 2008 for an educational program designed specifically for you. Attend symposia on chemistry in sports and health and learn how it impacts your life everyday; meet with graduate school recruiters. Focus on your professional future in chemistry by learning more about careers in public health and how to communicate and work effectively with cross-functional teams. Hear eminent scientist Richard B. Silverman (John Evans Professor of Chemistry, Northwestern University and author of The Organic Chemistry of Drug Design and Drug Action 2004) speak about "Drug Discovery: Ingenuity or Serendipity?" All events will take place at the Hilton Riverside Hotel in New Orleans, except the Undergraduate Research Poster Sessions and Sci-Mix, both of which will be held in Hall A of the Ernest N. Morial Convention Center.
DEFF Research Database (Denmark)
Wulf-Andersen, Trine Østergaard; Mogensen, Kevin; Hjort-Madsen, Peder
2013-01-01
The article presents a particular case of undergraduate students working on subprojects within the framework of their supervisors' (the authors') research project during Autumn Semester 2012 and Spring Semester 2013. The article's purpose is to show that an institutionalized focus on students...... as "research learners" rather than merely curriculum learners proves productive for both research and teaching. We describe the specific university learning context and the particular organization of undergraduate students' supervision and assistantships. The case builds on and further enhances a well......-established and proven university model of participant-directed, problem-oriented project work. We explore students' and researchers' experiences of being part of the collaboration, focusing on learning potentials and dilemmas associated with the multiple roles of researcher and student that characterized...
11. Integrating Research Experiences into the Undergraduate Education
Science.gov (United States)
Bauer, Wolfgang
2009-03-01
During the last seven years Michigan State University has been able to increase the number of physics and astrophysics majors by more than a factor of two. Part of this increase can be attributed to introducing special first-year courses on computational physics and on laboratory techniques, designed exclusively for physics majors. Investing into strengthening the Society of Physics Students and Science Theatre and into increased outreach activities also plays a role. But the largest effect is due to integrating a wide variety of research experiences into the Michigan State undergraduate physics and astrophysics experience. An overview of these activities will be given, and ways to upscale these efforts will be discussed.
12. Plasma Physics Research at an Undergraduate Institution
Science.gov (United States)
2007-11-01
Undergraduate research experiences have motivated many physics majors to continue their studies at the graduate level. The Department of Physics and Astronomy at SUNY Geneseo, a primarily undergraduate institution, recognizes this simple reality and is committed to ensuring research opportunities are available to interested majors beginning as early as their freshman year. Every year for more than a decade, as many as two dozen students and 8 faculty members have worked on projects related to high energy density physics and inertial confinement fusion during the summer months and the academic year. By working with their research sponsors, it has been possible to identify an impressive number of projects suitable for an institution such as Geneseo. These projects tend to be hands-on and require teamwork and innovation to be successful. They also take advantage of in-house capabilities such as the 2 MV tandem pelletron accelerator, a scanning electron microscope, a duoplasmatron ion deposition system and a 64 processor computing cluster. The end products of their efforts are utilized at the sponsoring facilities in support of nationally recognized programs. In this talk, I will discuss a number of these projects and point out what made them attractive and appropriate for an institution like Geneseo, the direct and indirect benefits of the research opportunities for the students and faculty, and how the national programs benefited from the cost-effective use of undergraduate research. In addition, I will discuss the importance of exposure for both students and faculty mentors to the larger scientific community through posters presentations at annual meetings such as the DPP and DNP. Finally, I will address the need for even greater research opportunities for undergraduate students in the future and the importance of establishing longer educational pipelines'' to satisfy the ever growing need for top-tier scientists and engineers in industry, academia and the
13. How to Successfully Incorporate Undergraduate Researchers Into a Complex Research Program at a Large Institution.
Science.gov (United States)
Weldon, Rebecca B; Reyna, Valerie F
2015-01-01
One feature of the Laboratory for Rational Decision Making at Cornell University is the integration of a large number of undergraduate students into a relatively elaborate research program. We describe our thorough screening process, laboratory structure, and our expectations for undergraduate researchers in our lab. We have a structure in place that helps maintain organization and enhance productivity, including scheduled weekly and monthly meetings, and selecting undergraduate and graduate team leaders to lead each research project. We discuss how it is important to encourage students to aim high and have a good attitude toward learning and problem solving. We emphasize that both initiative and teamwork are important in a large research laboratory. We also discuss the importance of giving students responsibility in connection with research projects-our undergraduate researchers engage in data analysis, interpretation of results, and have a high-level understanding of theory.
14. Laboratory techniques in plant molecular biology taught with UniformMu insertion alleles of maize
Science.gov (United States)
An undergraduate course - Laboratory Techniques in Plant Molecular Biology - was organized around our research application of UniformMu insertion alleles to investigate mitochondrial functions in plant reproduction. The course objectives were to develop students’ laboratory, record keeping, bioinfor...
15. The Exercise Physiology Laboratory--A Source of Health Promotion.
Science.gov (United States)
Norris, William; Norred, Robert
1988-01-01
A visit to the Exercise Physiology Laboratory at the University of Tennessee is part of a physical education class required of all undergraduate students. The laboratory demonstration stimulates student interest and enrollment in physical education. Benefits to students, the laboratory, and the school are described. (MT)
16. Two Undergraduate Projects for Data Acquisition and Control
Science.gov (United States)
Hiersche, Kelly; Pena, Tara; Grogan, Tanner; Wright, Matthew
We are designing two separate instruments for use in our undergraduate laboratory. In the first project, a Raspberry Pi is used to simultaneously monitor a large number of current and voltage readings and store them in a database. In our second project, we are constructing our own microcontrollers to work as a general-purpose interface based off work carried out in Review of Scientific Instruments 84, 103101 (2013). It was designed for low cost and simple construction, making it ideal for undergraduate level work. This circuit has room for two interchangeable daughter boards, giving it the capability to work as a general lab interface, lock-in detector, or waveform generator.
17. Integrating Clinical Neuropsychology into the Undergraduate Curriculum.
Science.gov (United States)
Puente, Antonio E.; And Others
1991-01-01
Claims little information exists in undergraduate education about clinical neuropsychology. Outlines an undergraduate neuropsychology course and proposes ways to integrate the subject into existing undergraduate psychology courses. Suggests developing specialized audio-visual materials for telecourses or existing courses. (NL)
18. Photometrics Laboratory
Data.gov (United States)
Federal Laboratory Consortium — Purpose:The Photometrics Laboratory provides the capability to measure, analyze and characterize radiometric and photometric properties of light sources and filters,...
19. Blackroom Laboratory
Data.gov (United States)
Federal Laboratory Consortium — FUNCTION: Enables evaluation and characterization of materials ranging from the ultraviolet to the longwave infrared (LWIR).DESCRIPTION: The Blackroom Laboratory is...
20. Target Laboratory
Data.gov (United States)
Federal Laboratory Consortium — [Part of the ATLAS user facility.] The Physics Division operates a target development laboratory that produces targets and foils of various thickness and substrates,...
CERN Document Server
Bard, Gregory V
2015-01-01
Professor Bard has provided a valuable service by carefully explaining everything an undergraduate student of mathematics, or a teacher of these topics, needs to get started with Sage quickly and easily. It will also be useful for any student or teacher of another STEM discipline. There is an excellent mix of the most frequently used commands, along with warnings about common pitfalls or caveats. I highly recommend it for anyone new to Sage, or who desires an overview of the system's impressive capabilities. -Robert A. Beezer, University of Puget Sound This book is a sort of "Missing Manual"
2. A Research-Based Laboratory Course Designed to Strengthen the Research-Teaching Nexus
Science.gov (United States)
Parra, Karlett J.; Osgood, Marcy P.; Pappas, Donald L., Jr.
2010-01-01
We describe a 10-week laboratory course of guided research experiments thematically linked by topic, which had an ultimate goal of strengthening the undergraduate research-teaching nexus. This undergraduate laboratory course is a direct extension of faculty research interests. From DNA isolation, characterization, and mutagenesis, to protein…
3. Detection of the "cp4 epsps" Gene in Maize Line NK603 and Comparison of Related Protein Structures: An Advanced Undergraduate Experiment
Science.gov (United States)
Swope, Nicole K.; Fryfogle, Patrick J.; Sivy, Tami L.
2015-01-01
A flexible, rigorous laboratory experiment for upper-level biochemistry undergraduates is described that focuses on the Roundup Ready maize line. The work is appropriate for undergraduate laboratory courses that integrate biochemistry, molecular biology, or bioinformatics. In this experiment, DNA is extracted and purified from maize kernel and…
4. Undergraduate Students' Information Search Practices
Science.gov (United States)
Nikolopoulou, Kleopatra; Gialamas, Vasilis
2011-01-01
This paper investigates undergraduate students' information search practices. The subjects were 250 undergraduate students from two university departments in Greece, and a questionnaire was used to document their search practices. The results showed that the Web was the primary information system searched in order to find information for…
5. Researching Undergraduate Social Science Research
Science.gov (United States)
Rand, Jane
2016-01-01
The experience(s) of undergraduate research students in the social sciences is under-represented in the literature in comparison to the natural sciences or science, technology, engineering and maths (STEM). The strength of STEM undergraduate research learning environments is understood to be related to an apprenticeship-mode of learning supported…
African Journals Online (AJOL)
This study examined the relationship between undergraduates' perception of the academic environment, their attitude to academic work and achievement. A total of 348 undergraduates who formed the sample were drawn from five departments in three universities in Nigeria. The study revealed that four dimensions of the ...
CERN Document Server
Tapp, Kristopher
2016-01-01
Matrix groups touch an enormous spectrum of the mathematical arena. This textbook brings them into the undergraduate curriculum. It makes an excellent one-semester course for students familiar with linear and abstract algebra and prepares them for a graduate course on Lie groups. Matrix Groups for Undergraduates is concrete and example-driven, with geometric motivation and rigorous proofs. The story begins and ends with the rotations of a globe. In between, the author combines rigor and intuition to describe the basic objects of Lie theory: Lie algebras, matrix exponentiation, Lie brackets, maximal tori, homogeneous spaces, and roots. This second edition includes two new chapters that allow for an easier transition to the general theory of Lie groups. From reviews of the First Edition: This book could be used as an excellent textbook for a one semester course at university and it will prepare students for a graduate course on Lie groups, Lie algebras, etc. … The book combines an intuitive style of writing w...
Science.gov (United States)
Tinker, John Richard, Jr.
1989-01-01
Discusses a course at the University of Wisconsin-Eau Claire which improved instruction in physical hydrogeology, chemical hydrogeology, and water resources. Describes 14 laboratory activities including objectives, methods, and a list of equipment needed. (Author/MVL)
9. Developing Effective Undergraduate Research Experience
Science.gov (United States)
Evans, Michael; Ilie, Carolina C.
2011-03-01
Undergraduate research is a valuable educational tool for students pursuing a degree in physics, but these experiences can become problematic and ineffective if not handled properly. Undergraduate research should be planned as an immersive learning experience in which the student has the opportunity to develop his/her skills in accordance with their interests. Effective undergraduate research experiences are marked by clear, measurable objectives and frequent student-professor collaboration. These objectives should reflect the long and short-term goals of the individual undergraduates, with a heightened focus on developing research skills for future use. 1. Seymour, E., Hunter, A.-B., Laursen, S. L. and DeAntoni, T. (2004), Establishing the benefits of research experiences for undergraduates in the sciences: First findings from a three-year study''. Science Education, 88: 493--534. 2. Behar-Horenstein, Linda S., Johnson, Melissa L. Enticing Students to Enter Into Undergraduate Research: The Instrumentality of an Undergraduate Course.'' Journal of College Science Teaching 39.3 (2010): 62-70.
10. Quantitative Investigations of Biodiesel Fuel Using Infrared Spectroscopy: An Instrumental Analysis Experiment for Undergraduate Chemistry Students
Science.gov (United States)
Ault, Andrew P.; Pomeroy, Robert
2012-01-01
Biodiesel has gained attention in recent years as a renewable fuel source due to its reduced greenhouse gas and particulate emissions, and it can be produced within the United States. A laboratory experiment designed for students in an upper-division undergraduate laboratory is described to study biodiesel production and biodiesel mixing with…
11. Comparing Online to Face-To-Face Delivery of Undergraduate Digital Circuits Content
Science.gov (United States)
LaMeres, Brock J.; Plumb, Carolyn
2014-01-01
This paper presents a comparison of online to traditional face-to-face delivery of undergraduate digital systems material. Two specific components of digital content were compared and evaluated: a sophomore logic circuits course with no laboratory, and a microprocessor laboratory component of a junior-level computer systems course. For each of…
12. Thermo-fluid simulation of a rotating disc with radial cooling passages / Francois Holtzhausen
OpenAIRE
Holtzhausen, Francois
2003-01-01
Turbine blade cooling via internal cooling channels is a very important aspect in modern-day gas turbine cycles. The need for blade cooling stems from the fact that higher cycle efficiencies requires higher maximum temperatures and therefore also higher turbine inlet temperatures. In order to evaluate the effects of these cooling flows on the cycle as a whole under various load conditions, it is necessary to simulate the compressible flow with heat transfer within the channe...
13. PREFACE: 31st UIT (Italian Union of Thermo-fluid-dynamics) Heat Transfer Conference 2013
Science.gov (United States)
Vitali, Luigi; Niro, Alfonso; Colombo, Luigi; Sotgia, Giorgio
2014-04-01
The annual Conference of the ''Unione Italiana di Termofluidodinamica'' (UIT) aims at promoting cooperation in the field of heat transfer and thermal sciences, by bringing together scientists and engineers working in related areas. The 31st UIT Conference was held in Moltrasio (Como), Italy, 25-27 June, 2013 at the Grand Hotel Imperiale. The response has been enthusiastic, with more than 70 quality contributions from 224 authors on heat transfer related topics: natural, forced and mixed convection, conduction, radiation, multi-phase fluid dynamics and interface phenomena, computational fluid dynamics, micro- and nano-scales, efficiency in energy systems, environmental technologies and buildings. To encourage the debate, the Conference Program has scheduled ample poster sessions and invited lectures from the best experts in the field along with a few of the most talented researchers. Keynote Lectures were given by Professor Roberto Mauri (University of Pisa), Professor Lounés Tadrist (Polytech Marseille) and Professor Maurizio Quadrio (Politecnico di Milano). This special volume collects a selection of the scientific contributions discussed during this conference; these works give a good overview of the state-of-the art Italian research in the field of Heat Transfer related topics. I would like to thank sincerely the authors for presenting their works at the conference and in this special issue. I would also like to extend my thanks to the Scientific Committee and the authors for their accurate review process of each paper for this special issue. Special thanks go to the organizing committee and to our sponsors. As a professor of Politecnico di Milano, let me say I am very proud to have been the chair of this conference in the 150th anniversary of my university. Professor Alfonso Niro Details of organizers, sponsors and committees, as well as further information, are available in the PDF
14. Thermo-fluid transport phenomena within a full-air fed pressurised suit
International Nuclear Information System (INIS)
Jason Dokhan; Tassos Karayiannis; Michael W Collins; Mark Atherton; Paul Edwards
2005-01-01
Full text of publication follows: Pressurised suits are used in radiological areas, during engineering outage periods of the Joint European Torus (JET) Fusion experiment at Culham, Oxford, UK. The suiting material is impermeable Polyurethane (PU), which is known for its high evaporative resistance. This quality resists the sweating mechanism so preventing sufficient heat to be lost to the environment and only allowing sweat from the body to pass into the clothing's micro-climate. As a consequence any excess heat produced due to exercise, work or the surrounding climate can not be transferred from the body. This can result in heat stress and in extreme circumstances heat exhaustion. The objective was to use Computational Fluid Dynamics (CFD) to better understand the underlying fluid mechanics and associated heat and mass transfer with the aim of improving the design and engineering substantiation of pressurised suits in terms of reduced risk of heat stress. It has been normal practice to date to model the geometry of a human wearing protective clothing (NBC) as a two dimensional cylinder surrounded by a porous medium. Here we address the use of realistic three dimensional scans of humans in protective clothing focussing on heat and mass transfer effects. Comparisons were made with past research on porous clothing, matching clothing and micro-climate thickness. Also the effects of 3D geometry on the fluid mechanics are shown. The effects of clothing impermeability on the fluid mechanics were examined using the commercially available CFD code Fluent 6. For numerical consistency a RANS approach to turbulence modelling was employed as per past research. (authors)
15. Basic thermo-fluid dynamic problems in high temperature heat exchangers
International Nuclear Information System (INIS)
McEligot, D.M.
1986-01-01
The authors consider high temperature heat exchangers to be ones where the heat transfer coefficients cannot be predicted confidently by classical analyses for pure forced convection with constant fluid properties. Alternatively, one could consider heat exchangers operating above some arbitrary temperature, say 1000F or 600C perhaps, to be at high temperature conditions. In that case, most common working fluids will be superheated vapors or gases. While some liquid metal heat exchangers are designed to operate in this range, the heat transfer coefficients of liquid metals are usually sufficiently high that the dominant thermal resistance would be due to the second fluid. This paper concentrates on convective heat transfer with gases. Typical applications include modular gas cooled nuclear reactors, proposed nuclear propulsion systems and space power plants, and superheaters in Rankine steam cycles
16. DNA - An integrated open-source optimization platform for thermo-fluid systems
DEFF Research Database (Denmark)
Pierobon, Leonardo; Wronski, Jorrit; Elmegaard, Brian
2014-01-01
of an air bottoming cycle unit recuperating the exhaust heat from an offshore power system. Subsequently, the control of a compressed air energy storage plant is modelled by interfacing with Matlab. Both cases take advantage of CoolProp’s table-based property interpolation scheme...... 110 fluids by interfacing CoolProp, a high-accuracy open-source property package for pure and pseudo-pure fluids, as well as humid air. Furthermore, the use as time integrator for other tools is demonstrated. The new features are unveiled in two case studies. The first example covers the optimization...
17. Thermo-fluid analysis of water cooled research reactors in natural convection
International Nuclear Information System (INIS)
2004-01-01
The STHIRP-1 computer program, which fundamentals are described in this work, uses the principles of the subchannels analysis and has the capacity to simulate, under steady state and transient conditions, the thermal and hydraulic phenomena which occur inside the core of a water-refrigerated research reactor under a natural convection regime. The models and empirical correlations necessary to describe the flow phenomena which can not be described by theoretical relations were selected according to the characteristics of the reactor operation. Although the primary objective is the calculation of research reactors, the formulation used to describe the fluid flow and the thermal conduction in the heater elements is sufficiently generalized to extend the use of the program for applications in power reactors and other thermal systems with the same features represented by the program formulations. To demonstrate the analytical capacity of STHIRP-l, there were made comparisons between the results calculated and measured in the research reactor TRIGA IPR-R1 of CDTN/CNEN. The comparisons indicate that the program reproduces the experimental data with good precision. Nevertheless, in the future there must be used more consistent experimental data to corroborate the validation of the program. (author)
18. A Solar Chimney for renewable energy production: thermo-fluid dynamic optimization by CFD analyses
Science.gov (United States)
Montelpare, S.; D'Alessandro, V.; Zoppi, A.; Costanzo, E.
2017-11-01
This paper analyzes the performance of a solar tower designed for renewable energy production. The Solar Chimney Power Plant (SCPP) involves technology that converts solar energy by means of three basic components: a large circular solar collector, a high tower in the center of the collector and a turbine generator inside the chimney. SCPPs are characterized by long term operational life, low maintenance costs, zero use of fuels, no use of water and no emissions of greenhouse gases. The main problem of this technology is the low energy global conversion coefficient due to the presence of four conversions: solar radiation > thermal energy > kinetic energy > mechanical energy > electric energy. This paper defines its starting point from the well known power plant of Manzanares in order to calibrate a numerical model based on finite volumes. Following that, a solar tower with reduced dimensions was designed and an analysis on various geometric parameters was conducted: on the inlet section, on the collector slope, and on the fillet radius among the SUPP sections. Once the optimal solution was identified, a curved deflectors able to induce a flow swirl along the vertical tower axis was designed.
19. Status of Thermo-Fluid Experimental Research on VHTR in Korea
International Nuclear Information System (INIS)
Kim, Min-Hwan; Hong, Seong-Deok; Kim, Yong-Wan; Shin, Dong-Ho; Lee, Jeong-Hun; Park, Goon-Cherl
2014-01-01
For reasons related to licensing uncertainty, economic slowdown, and questionable financial backing, no new nuclear facility projects have been undertaken in the United States since the Three Mile Island Incident in 1979; however, a need for such facilities (both nuclear power plants and nuclear fuel facilities) continues and various incentives leading to the start of a nuclear renaissance have occurred. One incentive is a complete overhaul by the US Nuclear Regulatory Commission of the earlier two step licensing process under 10 CFR 50. The earlier approach required first a construction permit and then an operating license, whereas the new approach allows a more streamlined (one step) combined license (COL) approach utilizing Standard Design Certifications via the regulatory framework created by 10 CFR 52. Other incentives include US Government backed loan guarantees as well as private company contributions.One aspect to the new process has been consideration and implementation of many new topic-specific regulations and industry standards which have continued to evolve during the past 30 years in spite of the lack of new plant design and construction activity. Therefore, an Owner attempting a new nuclear facility project under 10 CFR 52 needs to address a myriad of new requirements previously unconsidered.Several new projects including both power plants and fuel facilities have begun the new licensing process with its many new requirements to consider, but a uranium enrichment facility has run the gamut first. This paper will summarize many of the lessons learned from designing, constructing and testing this first new nuclear facility to be built in the US in over 30 years. (authors)
20. Visualization and measurement of thermo-fluid phenomena by using neutron radiography
Energy Technology Data Exchange (ETDEWEB)
Mishima, Kaichiro [Kyoto Univ., Kumatori, Osaka (Japan). Research Reactor Inst.
1998-03-01
Recently, neutron radiography is rapidly expanding its application to various fields incollaboration with the development of electronic imaging techniques. Particularly, in the field of thermal and fluid engineering, it has drawn much attention as an innovative and non-intrusive method for fluid-visualization and measurement using neutron beam as a probe. In this paper, some examples of applications are introduced on the high frame-rate imaging, quantification method (especially, determination of void fraction), and multidimensional measurement which are much interested in fluid measurement in relation to light water reactor safety and thermohydraulics. (author)
1. Human heart conjugate cooling simulation: unsteady thermo-fluid-stress analysis.
Science.gov (United States)
Abdoli, Abas; Dulikravich, George S; Bajaj, Chandrajit; Stowe, David F; Jahania, M Salik
2014-11-01
The main objective of this work was to demonstrate computationally that realistic human hearts can be cooled much faster by performing conjugate heat transfer consisting of pumping a cold liquid through the cardiac chambers and major veins while keeping the heart submerged in cold gelatin filling a cooling container. The human heart geometry used for simulations was obtained from three-dimensional, high resolution CT-angio scans. Two fluid flow domains for the right (pulmonic) and left (systemic) heart circulations, and two solid domains for the heart tissue and gelatin solution were defined for multi-domain numerical simulation. Detailed unsteady temperature fields within the heart tissue were calculated during the conjugate cooling process. A linear thermoelasticity analysis was performed to assess the stresses applied on the heart due to the coolant fluid shear and normal forces and to examine the thermal stress caused by temperature variation inside the heart. It was demonstrated that a conjugate cooling effort with coolant temperature at +4°C is capable of reducing the average heart temperature from +37°C to +8°C in 25 minutes for cases in which the coolant was steadily pumped only through major heart inlet veins and cavities. Copyright © 2014 John Wiley & Sons, Ltd.
2. Human heart conjugate cooling simulation: Unsteady thermo-fluid-stress analysis
OpenAIRE
Abdoli, Abas; Dulikravich, George S.; Bajaj, Chandrajit; Stowe, David F.; Jahania, M. Salik
2014-01-01
The main objective of this work was to demonstrate computationally that realistic human hearts can be cooled much faster by performing conjugate heat transfer consisting of pumping a cold liquid through the cardiac chambers and major veins while keeping the heart submerged in cold gelatin filling a cooling container. The human heart geometry used for simulations was obtained from three-dimensional, high resolution MRI scans. Two fluid flow domains for the right (pulmonic) and left (systemic) ...
3. Laboratory Tests
Science.gov (United States)
Laboratory tests check a sample of your blood, urine, or body tissues. A technician or your doctor ... compare your results to results from previous tests. Laboratory tests are often part of a routine checkup ...
4. National laboratories
International Nuclear Information System (INIS)
Moscati, G.
1983-01-01
The foundation of a 'National Laboratory' which would support a Research center in synchrotron radiation applications is proposed. The essential features of such a laboratory differing of others centers in Brazil are presented. (L.C.) [pt
5. Geomechanics Laboratory
Data.gov (United States)
Federal Laboratory Consortium — The Geomechanics Laboratory allows its users to measure rock properties under a wide range of simulated service conditions up to very high pressures and complex load...
6. Affordances of Instrumentation in General Chemistry Laboratories
Science.gov (United States)
Sherman, Kristin Mary Daniels
2010-01-01
The purpose of this study is to find out what students in the first chemistry course at the undergraduate level (general chemistry for science majors) know about the affordances of instrumentation used in the general chemistry laboratory and how their knowledge develops over time. Overall, students see the PASCO(TM) system as a useful and accurate…
7. Laboratory Experiment on Electrokinetic Remediation of Soil
Science.gov (United States)
Elsayed-Ali, Alya H.; Abdel-Fattah, Tarek; Elsayed-Ali, Hani E.
2011-01-01
Electrokinetic remediation is a method of decontaminating soil containing heavy metals and polar organic contaminants by passing a direct current through the soil. An undergraduate chemistry laboratory is described to demonstrate electrokinetic remediation of soil contaminated with copper. A 30 cm electrokinetic cell with an applied voltage of 30…
8. Building a Network Based Laboratory Environment
Directory of Open Access Journals (Sweden)
Sea Shuan Luo
2009-12-01
Full Text Available This paper presents a comparative study about the development of a network based laboratory environment in the “Unix introduction” course for the undergraduate students. The study results and the response from the students from 2005 to 2006 will be used to better understand what kind of method is more suitable for students. We also use the data collected to adjust our teaching strategy and try to build up a network based laboratory environment.
9. A Process Dynamics and Control Experiment for the Undergraduate Laboratory
Science.gov (United States)
Spencer, Jordan L.
2009-01-01
This paper describes a process control experiment. The apparatus includes a three-vessel glass flow system with a variable flow configuration, means for feeding dye solution controlled by a stepper-motor driven valve, and a flow spectrophotometer. Students use impulse response data and nonlinear regression to estimate three parameters of a model…
10. Stereoisomerism in Coordination Chemistry: A Laboratory Experiment for Undergraduate Students.
Science.gov (United States)
Gargallo, Maria Fe; And Others
1988-01-01
Describes an experimental procedure to acquaint inorganic chemistry students with stereochemical concepts using tris-(2,3-butanediamine)cobalt(III). Notes two isomeric forms exist and both form metal chelates. Separation is accomplished by chromatography and analysis is by NMR and infrared spectroscopy. Provides spectra of isomers. (MVL)
11. A Membrane Gas Separation Experiment for the Undergraduate Laboratory.
Science.gov (United States)
Davis, Richard A.; Sandall, Orville C.
1991-01-01
Described is a membrane experiment that provides students with experience in fundamental engineering skills such as mass balances, modeling, and using the computer as a research tool. Included are the experimental design, theory, method of solution, sample calculations, and conclusions. (KR)
12. A "Greenhouse Gas" Experiment for the Undergraduate Laboratory
Science.gov (United States)
Gomez, Elaine; Paul, Melissa; Como, Charles; Barat, Robert
2014-01-01
This experiment and analysis offer an effective experience in greenhouse gas reduction. Ammoniated water is flowed counter-current to a simulated flue gas of air and CO2 in a packed column. The gaseous CO2 concentrations are measured with an on-line, non- dispersive, infrared analyzer. Column operating parameters include total gas flux, dissolved…
13. An Undergraduate Laboratory Activity on Molecular Dynamics Simulations
Science.gov (United States)
Spitznagel, Benjamin; Pritchett, Paige R.; Messina, Troy C.; Goadrich, Mark; Rodriguez, Juan
2016-01-01
Vision and Change [AAAS, 2011] outlines a blueprint for modernizing biology education by addressing conceptual understanding of key concepts, such as the relationship between structure and function. The document also highlights skills necessary for student success in 21st century Biology, such as the use of modeling and simulation. Here we…
14. Discovery of "Escherichia coli" CRISPR Sequences in an Undergraduate Laboratory
Science.gov (United States)
Militello, Kevin T.; Lazatin, Justine C.
2017-01-01
Clustered regularly interspaced short palindromic repeats (CRISPRs) represent a novel type of adaptive immune system found in eubacteria and archaebacteria. CRISPRs have recently generated a lot of attention due to their unique ability to catalog foreign nucleic acids, their ability to destroy foreign nucleic acids in a mechanism that shares some…
15. Undergraduate Training in Nutritional Science
Science.gov (United States)
Briggs, George M.
1972-01-01
Discusses need to establish minimum standards of training for nutrition educators,'' and standardized curricula at the undergraduate level. Gives attention to definitions, adequate training, and suggested guidelines as a starting point for further discussion. (LK)
16. Undergraduate Measurements For Fission Reactor Applications
Science.gov (United States)
Hicks, S. F.; Kersting, L. J.; Lueck, C. J.; McDonough, P.; Crider, B. P.; McEllistrem, M. T.; Peters, E. E.; Vanhoy, J. R.
2011-06-01
Undergraduate students at the University of Dallas (UD) have investigated elastic and inelastic neutron scattering cross sections on structural materials important for criticality considerations in nuclear fission processes. Neutrons scattered off of 23Na and NatFe were detected using neutron time-of-flight techniques at the University of Kentucky Low-Energy Nuclear Accelerator Facility. These measurements are part of an effort to increase the efficiency of power generation from existing fission reactors in the US and in the design of new fission systems. Students have learned the basics of how to operate the Model CN Van de Graaff generator at the laboratory, setup detectors and electronics, use data acquisition systems, and they are currently analyzing the angular dependence of the scattered neutrons for incident neutron energies of 3.57 and 3.80 MeV. Most students participating in the project will use the research experience as the material for their undergraduate research thesis required for all Bachelor of Science students at the University of Dallas. The first student projects on this topic were completed during the summer of 2010; an overview of student participation in this investigation and their preliminary results will be presented.
Science.gov (United States)
Rees, L; Wass, J
1993-01-23
Pressures from students and teachers, from professional bodies, and from changes in the way health care is delivered are all forcing a rethink of how medical students should be taught. These pressures may be more intense in London but are not confined to it. The recommendation the Tomlinson report advocates that has been generally welcomed is for more investment in primary care in London. General practitioners have much to teach medical schools about effective ways of learning, but incentives for teaching students in general practice are currently low, organising such teaching is difficult and needs resources, and resistance within traditional medical school hierarchies needs to be overcome. Likewise, students value learning within local communities, but the effort demanded of public health departments and community organisations is great at a time when they are under greater pressure than ever before. The arguments over research that favour concentration in four multifaculty schools are less clear cut for undergraduate education, where personal support for students is important. An immediate concern is that the effort demanded for reorganising along the lines suggested by Tomlinson will not leave medical schools much energy for innovating.
18. 27-A: Team-Centered, Project-Based Learning in an Undergraduate Neurobiology Course
OpenAIRE
Beumer, A.E.; Briggs, A.G.; Sanderson, S.K.; Morgan., S.K.; Caldari, C.; Carson, S.; Caruso, J.P.; Israel, N.; Lovelace, M.; Saunders, M.J.; DeBoy, C.A.; Gabriel, S.G.; Peterson, M.P.; Gollery, S.W.; Gunn, K.
2015-01-01
Too often in a predetermined or ?cookbook? laboratory, students do not make the connection between experiential methods, the concepts behind these methods, and the application of these methods to different situations. This semester-long laboratory exercise was designed to provide students with an inquiry-based or classroom undergraduate research experience (CURE) laboratory project that incorporates commonly used microbiological lab concepts and techniques and to see whether this type of labo...
19. Students' perceptions of academic dishonesty in the chemistry classroom laboratory
Science.gov (United States)
del Carlo, Dawn I.; Bodner, George M.
2004-01-01
Although the literature on both academic dishonesty and scientific misconduct is extensive, research on academic dishonesty has focused on quizzes, exams, and papers, with the virtual exclusion of the classroom laboratory. This study examined the distinctions undergraduate chemistry majors made between academic dishonesty in the classroom laboratory and scientific misconduct in the research laboratory. Across the spectrum of undergraduate chemistry courses, from the introductory course for first-semester chemistry majors to the capstone course in instrumental analysis, we noted that students believe the classroom lab is fundamentally different from a research or industrial lab. This difference is so significant that it carries over into students' perceptions of dishonesty in these two environments.
20. An "in Silico" DNA Cloning Experiment for the Biochemistry Laboratory
Science.gov (United States)
Elkins, Kelly M.
2011-01-01
This laboratory exercise introduces students to concepts in recombinant DNA technology while accommodating a major semester project in protein purification, structure, and function in a biochemistry laboratory for junior- and senior-level undergraduate students. It is also suitable for forensic science courses focused in DNA biology and advanced…
1. Evolution of a Low Cost Control Engineering Laboratory.
Science.gov (United States)
El-Shirbeeny, El-Hosseiny Taha
1986-01-01
Presents an approach for building an inexpensive control engineering laboratory to support control courses in an undergraduate engineering program. Outlines the use of simple amplifier circuits and small personal computers in performing control experiments. Proposes an optimum configuration of the laboratory for minimum servicing and adequate…
2. Determination of Absolute Zero Using a Computer-Based Laboratory
Science.gov (United States)
Amrani, D.
2007-01-01
We present a simple computer-based laboratory experiment for evaluating absolute zero in degrees Celsius, which can be performed in college and undergraduate physical sciences laboratory courses. With a computer, absolute zero apparatus can help demonstrators or students to observe the relationship between temperature and pressure and use…
3. Low-Cost Virtual Laboratory Workbench for Electronic Engineering
Science.gov (United States)
Achumba, Ifeyinwa E.; Azzi, Djamel; Stocker, James
2010-01-01
The laboratory component of undergraduate engineering education poses challenges in resource constrained engineering faculties. The cost, time, space and physical presence requirements of the traditional (real) laboratory approach are the contributory factors. These resource constraints may mitigate the acquisition of meaningful laboratory…
4. Laboratory Building
Energy Technology Data Exchange (ETDEWEB)
Herrera, Joshua M. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
2015-03-01
This report is an analysis of the means of egress and life safety requirements for the laboratory building. The building is located at Sandia National Laboratories (SNL) in Albuquerque, NM. The report includes a prescriptive-based analysis as well as a performance-based analysis. Following the analysis are appendices which contain maps of the laboratory building used throughout the analysis. The top of all the maps is assumed to be north.
International Nuclear Information System (INIS)
Edwards, R.M.; Power, M.A.; Bryan, M.
1992-01-01
A sequence of reactor and related experiments has been a central element of a senior-level laboratory course at Pennsylvania State University (Penn State) for more than 20 yr. A new experiment has been developed where the students program and operate a computer controller that manipulates the speed of a secondary control rod to regulate TRIGA reactor power. Elementary feedback control theory is introduced to explain the experiment, which emphasizes the nonlinear aspect of reactor control where power level changes are equivalent to a change in control loop gain. Digital control of nuclear reactors has become more visible at Penn State with the replacement of the original analog-based TRIGA reactor control console with a modern computer-based digital control console. Several TRIGA reactor dynamics experiments, which comprise half of the three-credit laboratory course, lead to the control experiment finale: (a) digital simulation, (b) control rod calibration, (c) reactor pulsing, (d) reactivity oscillator, and (e) reactor noise
6. Analytical Laboratory
Data.gov (United States)
Federal Laboratory Consortium — The Analytical Labspecializes in Oil and Hydraulic Fluid Analysis, Identification of Unknown Materials, Engineering Investigations, Qualification Testing (to support...
7. Chemistry Laboratory
Data.gov (United States)
Federal Laboratory Consortium — Purpose: To conduct fundamental studies of highway materials aimed at understanding both failure mechanisms and superior performance. New standard test methods are...
8. Propulsion Laboratory
Data.gov (United States)
Federal Laboratory Consortium — The Propulsion Lab simulates field test conditions in a controlled environment, using standardized or customized test procedures. The Propulsion Lab's 11 cells can...
9. Psychology Laboratory
Data.gov (United States)
Federal Laboratory Consortium — This facility provides testing stations for computer-based assessment of cognitive and behavioral Warfighter performance. This 500 square foot configurable space can...
10. Dynamics Laboratory
Data.gov (United States)
Federal Laboratory Consortium — The Dynamics Lab replicates vibration environments for every Navy platform. Testing performed includes: Flight Clearance, Component Improvement, Qualification, Life...
11. Visualization Laboratory
Data.gov (United States)
Federal Laboratory Consortium — FUNCTION: Evaluates and improves the operational effectiveness of existing and emerging electronic warfare systems. By analyzing and visualizing simulation results...
12. An Undergraduate Student's Perspective on Geoscience Research
Science.gov (United States)
Wilder, A.; Feeley, T.; Michelfelder, G.
2011-12-01
13. A Guided-Inquiry pH Laboratory Exercise for Introductory Biological Science Laboratories
Science.gov (United States)
Snodgrass, Meagan A.; Lux, Nicholas; Metz, Anneke M.
2011-01-01
There is a continuing need for engaging inquiry-based laboratory experiences for advanced high school and undergraduate biology courses. The authors describe a guided-inquiry exercise investigating the pH-dependence of lactase enzyme that uses an inexpensive, wide-range buffering system, lactase dietary supplement, over-the-counter glucose test…
Science.gov (United States)
Troischt, Parker; Koopmann, Rebecca A.; Haynes, Martha P.; ALFALFA Team
2016-01-01
The NSF-sponsored Undergraduate ALFALFA (Arecibo Legacy Fast ALFA) Team (UAT) is a consortium of 19 institutions founded to promote undergraduate research and faculty development within the extragalactic ALFALFA HI blind survey project and follow-up programs. In this talk we present outcomes for the more than 250 undergraduate students who have who have participated in the program during the 8 years of funding. 40% of these students have been women and members of underrepresented groups. To date 148 undergraduate students have attended annual workshops at Arecibo Observatory, interacting with faculty, graduate students, their peers, and Arecibo staff in lectures, group activities, tours, and observing runs. Team faculty have supervised 159 summer research projects and 120 academic year (e.g., senior thesis) projects. 68 students have traveled to Arecibo Observatory for observing runs and 55 have presented their results at national meetings such as the AAS. Through participation in the UAT, students are made aware of career paths they may not have previously considered. More than 90% of alumni are attending graduate school and/or pursuing a career in STEM. 42% of those pursuing graduate degrees in Physics or Astronomy are women. This work has been supported by NSF grants AST-0724918/0902211, AST-075267/0903394, AST-0725380, and AST-1211005
Science.gov (United States)
Heiles, C.
1998-12-01
We currently offer three advanced laboratory courses for undergraduate majors: optical, IR, and radio. These courses contain both intellectual and practical content; in this talk we focus on the radio lab as a representative example. The first half of the semester concentrates on fundamentals of microwave electronics and radio astronomy techniques in four formal laboratory exercises which emphasize hands-on use of microwave devices, laboratory instruments, and computer-controlled data taking. The second half of the course emphasizes astronomy, using a horn with ~ 1 m(2) aperture to map the HI in the Galaxy and a two-element interferometer composed of ~ 1 m diameter dishes on a ~ 10 m baseline to measure accurate positions of radio sources and accurate diameters for the Sun and Moon. These experiments and observations offer ideal opportunities for teaching coordinates, time, rotation matrices, data reduction techniques, least squares, signal processing, image processing, Fourier transforms, and laboratory and astronomical instrumentation. The students can't get along without using computers as actually used by astronomers. We stay away from packaged software such as IRAF, which are black boxes''; rather, students learn far more by writing their own software, usually for the first time. They use the IDL language to take and reduce data and prepare them for the lab reports. We insist on quality reports---including tables, postscript graphs and images, correct grammar, spelling, and all the rest---and we strongly urge (successfully!) the students to use LATEX. The other two lab courses have the same emphasis: the guiding spirit is to place the students in a real-life research-like situation. There is too much to do, so students perform the work in small groups of 3 or 4 and groups are encouraged to share their knowledge. Lab reports are written individually. These courses are very demanding, requiring an average of 20 hours per week from the students (and probably
16. SPIN-UP and Preparing Undergraduate Physics Majors for Careers in Industry
Science.gov (United States)
Howes, Ruth
2011-03-01
Seven years ago, the Strategic Programs for Innovations in Undergraduate Physics (SPIN-UP) Report produced by the National Task Force on Undergraduate Physics identified several key characteristics of thriving undergraduate physics departments including steps these departments had taken to prepare students better for careers in industry. Today statistical data from AIP shows that almost 40% of students graduating with a degree in physics seek employment as soon as they graduate. Successful undergraduate physics programs have taken steps to adapt their rigorous physics programs to ensure that graduating seniors have the skills they need to enter the industrial workplace as well as to go on to graduate school in physics. Typical strategies noted during a series of SPIN-UP workshops funded by a grant from NSF to APS, AAPT, and AIP include flexible curricula, early introduction of undergraduates to research techniques, revised laboratory experiences that provide students with skills they need to move directly into jobs, and increased emphasis on soft'' skills such as communication and team work. Despite significant success, undergraduate programs face continuing challenges in preparing students to work in industry, most significantly the fact that there is no job called physicist'' at the undergraduate level. supported by grant NSF DUE-0741560.
17. Integrating Chemistry Laboratory Instrumentation into the Industrial Internet: Building, Programming, and Experimenting with an Automatic Titrator
Science.gov (United States)
Famularo, Nicole; Kholod, Yana; Kosenkov, Dmytro
2016-01-01
This project is designed to improve physical chemistry and instrumental analysis laboratory courses for undergraduate students by employing as teaching tools novel technologies in electronics and data integration using the industrial Internet. The project carried out by upper-division undergraduates is described. Students are exposed to a complete…
18. Professional practice and construction undergraduates' employability skills
OpenAIRE
Vohmann, B.; Frame, I.
2016-01-01
Employability skills are known to be valuable to undergraduates when entering the workplace and expected by employers, yet, in construction as in many disciplines, these skills often are not well developed. However, construction professionals frequently work in complex dynamic environments and employability skills may enhance undergraduates' practitioner effectiveness. Therefore it is important tutors exploit opportunities to help undergraduates develop their employability skills. This paper ...
19. Elastomers Laboratory
Data.gov (United States)
Federal Laboratory Consortium — Primary capabilities include: elastomer compounding in various sizes (micro, 3x5, 8x12, 8x15 rubber mills); elastomer curing and post curing (two 50-ton presses, one...
20. Laboratory Tests
Science.gov (United States)
... Medical Devices Radiation-Emitting Products Vaccines, Blood & Biologics Animal & ... What are lab tests? Laboratory tests are medical devices that are intended for use on samples of blood, urine, or other tissues ...
1. Audio Laboratory
Data.gov (United States)
Federal Laboratory Consortium — FUNCTION: Provides an environment and facilities for auditory display research. A primary focus is the performance use of binaurally rendered 3D sound in conjunction...
2. Semiconductor Electrical Measurements Laboratory
Data.gov (United States)
Federal Laboratory Consortium — The Semiconductor Electrical Measurements Laboratory is a research laboratory which complements the Optical Measurements Laboratory. The laboratory provides for Hall...
3. An Undergraduate Experiment in Polyester (PET) Synthesis
Science.gov (United States)
Cammidge, Andrew N.
1999-02-01
The most important polyester manufactured industrially is PET (polyethyleneterephthalate). We describe an experiment that conveniently mimics the industrial synthesis in the undergraduate laboratory. The first step of the reaction is a base-catalyzed transesterification between ethane diol and dimethylterephthalate. Methanol is distilled off to drive the reaction to completion. Excess ethane diol is employed to suppress formation of higher oligomers. The intermediate (bis-(2-hydroxyethyl)terephthalate) is isolated by crystallization and filtration and characterized by 1H NMR spectroscopy. In the second step the monomer is heated (with and without acid catalyst) to form polymer. Samples are removed at intervals and their physical properties are recorded as they cool. These properties are used to qualitatively monitor polymerization. This experiment reinforces some fundamental chemical concepts and introduces the students to new laboratory procedures. The students perform a distillation and apply their knowledge of the reaction equilibrium to calculate the volume of distillate (methanol) expected. The reversible nature of esterification reactions is emphasized during the polymerization step (acid-catalyzed), where the process is driven towards polymer formation by the removal (evaporation) of ethane diol.
4. Detecting student copying in a corpus of science laboratory reports
OpenAIRE
Atwell, ES; Gent, JP; Medori, JDM; Souter, DC
2003-01-01
This case study is an evaluation of generic, general-purpose plagiarism detection systems applied to a specific domain and task: detecting intra-class student copying in a corpus of Biomedical Science laboratory reports. From the outset, our project had the practical, pragmatic aim to find a workable solution to a specific problem. Biomedical Science undergraduates learn experimental methods by working through a series of laboratory experiments and reporting on their results. These laboratory...
5. Teaching Economic Forecasting to Undergraduates.
Science.gov (United States)
Donihue, Michael R.
1995-01-01
Contends that academic departments have come under increasing scrutiny in terms of the scope of curriculum and teaching methods. Describes a senior undergraduate economics course in which the primary objective was to give students opportunities to combine theoretical training with quantitative skills and apply them to real-world problems. (CFR)
6. A conference experience for undergraduates
International Nuclear Information System (INIS)
Collins, L.A.; Magee, N.H.; Bryant, H.C.; Zeilik, M.
1999-01-01
Programs launched by many universities and the federal government expose many undergraduate students in the physical sciences to research early in their careers. However, in their research experiences, undergraduates are not usually introduced to the modes by which scientific knowledge, which they may have helped gather, is communicated and evaluated by working scientists. Nor is it always made clear where the research frontiers really lie. To this end, we guided a selected group of undergraduates through a national scientific conference, followed by a week of tutorials and discussions to help them better understand what had transpired. The program complemented the basic undergraduate research endeavors by emphasizing the importance of disseminating results both to other scientists and to society in general. Tutors and discussion leaders in the second week were experts in their fields and included some of the invited speakers from the main meeting. A considerable improvement in the understanding of the issues and prospects for a career in physics was discernible among the students after their two-week experience. copyright 1999 American Association of Physics Teachers
7. Rethinking Undergraduate Physical Chemistry Curricula
Science.gov (United States)
Miller, Stephen R.
2016-01-01
A summary of fundamental changes made to the undergraduate physical chemistry curriculum in the Chemistry Department at Gustavus Adolphus College (beginning in the 2013-2014 academic year) is presented. The yearlong sequence now consists of an introductory semester covering both quantum mechanics and thermodynamics/kinetics, followed by a second…
8. Undergraduate Students' Attitudes toward Biodiversity
Science.gov (United States)
Huang, Hui-Ju; Lin, Yu-Teh Kirk
2014-01-01
The study investigated American and Taiwan undergraduate students' attitudes toward biodiversity. The survey questionnaire consisted of statements prompted by the question "To what extent do you agree with the following statements about problems with the biodiversity issues." Students indicated strongly disagree, disagree, agree,…
9. Undergraduate research: a case study
NARCIS (Netherlands)
Koppelman, Hermannus; van Dijk, Elisabeth M.A.G.; van der Hoeven, Gerrit
This paper describes a one semester research course for undergraduates of computing programs. Students formulate a research proposal, conduct research and write a full paper. They present the results at a one-day student conference. On the one hand we offer the students a lot of structure and
10. Undergraduates, Technology, and Social Connections
Science.gov (United States)
Palmer, Betsy; Boniek, Susan; Turner, Elena; Lovell, Elyse D'nn
2014-01-01
The purpose of this study was to examine the spectrum of undergraduate students' social interactions and related technological tools. Qualitative methods were used for this phenomenological study exploring 35 in-person interviews, with horizonalization in an open coding system secured by in-depth analysis which revealed nuanced themes and…
11. EERE Resources for Undergraduate Students
Energy Technology Data Exchange (ETDEWEB)
None
2016-10-01
Looking to expand your experience outside of the classroom? The Office of Energy Efficiency and Renewable Energy (EERE) at the U.S. Department of Energy (DOE) has a number of resources available for undergraduate students, including competitions, internships, and career planning information to help you navigate the education to employment pathway in energy.
12. Astrology Beliefs among Undergraduate Students
Science.gov (United States)
Sugarman, Hannah; Impey, Chris; Buxner, Sanlyn; Antonellis, Jessie
2011-01-01
A survey of the science knowledge and attitudes toward science of nearly 10000 undergraduates at a large public university over a 20-year period included several questions addressing student beliefs in astrology and other forms of pseudoscience. The results from our data reveal that a large majority of students (78%) considered astrology "very" or…
13. EERE Resources for Undergraduate Students
Energy Technology Data Exchange (ETDEWEB)
None
2015-04-01
Looking to expand your experience outside of the classroom? The Office of Energy Efficiency and Renewable Energy (EERE) at the U.S. Department of Energy (DOE) has a number of resources available for undergraduate students, including competitions, internships, and career planning information to help you navigate the education to employment pathway in energy.
14. A Review of Undergraduate Physics
Science.gov (United States)
Bayman, Benjamin F.; Hamermesh, Morton
1986-02-01
A study aid for senior and graduate level students needing a review of undergraduate physics. Covers a broad range of topics, with carefully worked examples illustrating important problem-solving methods. A collection of self-test problems helps students prepare for the College Entrance Advanced Physics Examination and the Qualifying Written Examination for the PhD.
15. Bioinformatics and the Undergraduate Curriculum
Science.gov (United States)
Maloney, Mark; Parker, Jeffrey; LeBlanc, Mark; Woodard, Craig T.; Glackin, Mary; Hanrahan, Michael
2010-01-01
Recent advances involving high-throughput techniques for data generation and analysis have made familiarity with basic bioinformatics concepts and programs a necessity in the biological sciences. Undergraduate students increasingly need training in methods related to finding and retrieving information stored in vast databases. The rapid rise of…
16. Smart Grid Integration Laboratory
Energy Technology Data Exchange (ETDEWEB)
2011-12-22
The initial federal funding for the Colorado State University Smart Grid Integration Laboratory is through a Congressionally Directed Project (CDP), DE-OE0000070 Smart Grid Integration Laboratory. The original program requested in three one-year increments for staff acquisition, curriculum development, and instrumentation all which will benefit the Laboratory. This report focuses on the initial phase of staff acquisition which was directed and administered by DOE NETL/ West Virginia under Project Officer Tom George. Using this CDP funding, we have developed the leadership and intellectual capacity for the SGIC. This was accomplished by investing (hiring) a core team of Smart Grid Systems engineering faculty focused on education, research, and innovation of a secure and smart grid infrastructure. The Smart Grid Integration Laboratory will be housed with the separately funded Integrid Laboratory as part of CSU's overall Smart Grid Integration Center (SGIC). The period of performance of this grant was 10/1/2009 to 9/30/2011 which included one no cost extension due to time delays in faculty hiring. The Smart Grid Integration Laboratory's focus is to build foundations to help graduate and undergraduates acquire systems engineering knowledge; conduct innovative research; and team externally with grid smart organizations. Using the results of the separately funded Smart Grid Workforce Education Workshop (May 2009) sponsored by the City of Fort Collins, Northern Colorado Clean Energy Cluster, Colorado State University Continuing Education, Spirae, and Siemens has been used to guide the hiring of faculty, program curriculum and education plan. This project develops faculty leaders with the intellectual capacity to inspire its students to become leaders that substantially contribute to the development and maintenance of Smart Grid infrastructure through topics such as: (1) Distributed energy systems modeling and control; (2) Energy and power conversion; (3
17. Organization of an undergraduate research group
International Nuclear Information System (INIS)
Hill, J.; Noteboom, E.
1995-01-01
Traditionally, research groups consist of senior physicists, staff members, and graduate students. The physics department at Creighton University has formed a Relativistic Heavy Ion physics research group consisting primarily of undergraduate students. Although senior staff and graduate students are actively involved, undergraduate research and the education of undergraduates is the focus of the group. The presentation, given by two undergraduate members of the group, will outline progress made in the group's organization, discuss the benefits to the undergraduate group members, and speak to the balance which must be struck between education concerns and research goals
18. Merits of Undergraduate and High School Research
Science.gov (United States)
Kenney, John
2016-06-01
19. Sol-Gel Synthesis of a Biotemplated Inorganic Photocatalyst: A Simple Experiment for Introducing Undergraduate Students to Materials Chemistry
Science.gov (United States)
Boffa, Vittorio; Yue, Yuanzheng; He, Wen
2012-01-01
As part of a laboratory course, undergraduate students were asked to use baker's yeast cells as biotemplate in preparing TiO[subscript 2] powders and to test the photocatalytic activity of the resulting materials. This laboratory experience, selected because of the important environmental implications of soft chemistry and photocatalysis, provides…
20. Preservice laboratory education strengthening enhances sustainable laboratory workforce in Ethiopia.
Science.gov (United States)
Fonjungo, Peter N; Kebede, Yenew; Arneson, Wendy; Tefera, Derese; Yimer, Kedir; Kinde, Samuel; Alem, Meseret; Cheneke, Waqtola; Mitiku, Habtamu; Tadesse, Endale; Tsegaye, Aster; Kenyon, Thomas
2013-10-28
There is a severe healthcare workforce shortage in sub Saharan Africa, which threatens achieving the Millennium Development Goals and attaining an AIDS-free generation. The strength of a healthcare system depends on the skills, competencies, values and availability of its workforce. A well-trained and competent laboratory technologist ensures accurate and reliable results for use in prevention, diagnosis, care and treatment of diseases. An assessment of existing preservice education of five medical laboratory schools, followed by remedial intervention and monitoring was conducted. The remedial interventions included 1) standardizing curriculum and implementation; 2) training faculty staff on pedagogical methods and quality management systems; 3) providing teaching materials; and 4) procuring equipment for teaching laboratories to provide practical skills to complement didactic education. A total of 2,230 undergraduate students from the five universities benefitted from the standardized curriculum. University of Gondar accounted for 252 of 2,230 (11.3%) of the students, Addis Ababa University for 663 (29.7%), Jimma University for 649 (29.1%), Haramaya University for 429 (19.2%) and Hawassa University for 237 (10.6%) of the students. Together the universities graduated 388 and 312 laboratory technologists in 2010/2011 and 2011/2012 academic year, respectively. Practical hands-on training and experience with well-equipped laboratories enhanced and ensured skilled, confident and competent laboratory technologists upon graduation. Strengthening preservice laboratory education is feasible in resource-limited settings, and emphasizing its merits (ample local capacity, country ownership and sustainability) provides a valuable source of competent laboratory technologists to relieve an overstretched healthcare system.
1. Asking the Next Generation: The Implementation of Pre-University Students' Ideas about Physics Laboratory Preparation Exercises
Science.gov (United States)
Dunnett, K.; Bartlett, P. A.
2018-01-01
It was planned to introduce online pre-laboratory session activities to a first-year undergraduate physics laboratory course to encourage a minimum level of student preparation for experiments outside the laboratory environment. A group of 16 and 17 year old laboratory work-experience students were tasked to define and design a pre-laboratory…
2. Effect of Using Separate Laboratory and Lecture Courses for Introductory Crop Science on Student Performance.
Science.gov (United States)
Wiebold, W. J.; Slaughter, Leon
1986-01-01
Reviews a study that examined the effects of laboratories on the grade performance of undergraduates in an introductory crop science course. Results indicated that students enrolled in lecture and laboratory concurrently did not receive higher lecture grades than students enrolled solely in lecture, but did have higher laboratory grades. (ML)
3. Students' Perceptions of a Project-Based Organic Chemistry Laboratory Environment: A Phenomenographic Approach
Science.gov (United States)
Burrows, Nikita L.; Nowak, Montana K.; Mooring, Suazette R.
2017-01-01
Students can perceive the laboratory environment in a variety of ways that can affect what they take away from the laboratory course. This qualitative study characterizes undergraduate students' perspectives of a project-based Organic Chemistry laboratory using the theoretical framework of phenomenography. Eighteen participants were interviewed in…
4. Isotope laboratories
International Nuclear Information System (INIS)
1978-01-01
This report from the Dutch Ministry of Health is an advisory document concerned with isotope laboratories in hospitals, in connection with the Dutch laws for hospitals. It discusses which hospitals should have isotope laboratories and concludes that as many hospitals as possible should have small laboratories so that emergency cases can be dealt with. It divides the Netherlands into regions and suggests which hospitals should have these facilities. The questions of how big each lab. is to be, what equipment each has, how each lab. is organised, what therapeutic and diagnostic work should be carried out by each, etc. are discussed. The answers are provided by reports from working groups for in vivo diagnostics, in vitro diagnostics, therapy, and safety and their results form the criteria for the licences of isotope labs. The results of a questionnaire for isotope labs. already in the Netherlands are presented, and their activities outlined. (C.F.)
5. Laboratory: Undergraduate Laboratory Experiment Teaching Fundamental Concepts of Rheology in Context of Sickle Cell Anemia
Science.gov (United States)
Vernengo, Jennifer; Purdy, Caitlin; Farrell, Stephanie
2014-01-01
This paper describes a biomedical engineering experiment that introduces students to rheology. Healthy and sickle-cell blood analogs are prepared that are composed of chitosan particles suspended in aqueous glycerol solutions, which substitute for RBCs and plasma, respectively. Students study flow properties of the blood analogs with a viscometer…
6. Using Free Computational Resources to Illustrate the Drug Design Process in an Undergraduate Medicinal Chemistry Course
Science.gov (United States)
Rodrigues, Ricardo P.; Andrade, Saulo F.; Mantoani, Susimaire P.; Eifler-Lima, Vera L.; Silva, Vinicius B.; Kawano, Daniel F.
2015-01-01
Advances in, and dissemination of, computer technologies in the field of drug research now enable the use of molecular modeling tools to teach important concepts of drug design to chemistry and pharmacy students. A series of computer laboratories is described to introduce undergraduate students to commonly adopted "in silico" drug design…
7. Self-Cleaning Surfaces: A Third-Year Undergraduate Research Project
Science.gov (United States)
Haines, Ronald S.; Wu, Alex H. F.; Zhang, Hua; Coffey, Jacob; Huddle, Thomas; Lafountaine, Justin S.; Lim, Zhi-Jun; White, Eugene A.; Tuong, Nam T.; Lamb, Robert N.
2009-01-01
Superhydrophobic (non water-wettable) surfaces can possess the ability to self-clean (the so-called "lotus effect"). The task of devising the apparatus and method for quantifying this self-cleaning effect was offered as a project in a third-year undergraduate laboratory course. Using commonly available equipment the students devised a…
8. Affordable Hands-On DNA Sequencing and Genotyping: An Exercise for Teaching DNA Analysis to Undergraduates
Science.gov (United States)
Shah, Kushani; Thomas, Shelby; Stein, Arnold
2013-01-01
In this report, we describe a 5-week laboratory exercise for undergraduate biology and biochemistry students in which students learn to sequence DNA and to genotype their DNA for selected single nucleotide polymorphisms (SNPs). Students use miniaturized DNA sequencing gels that require approximately 8 min to run. The students perform G, A, T, C…
9. Effectiveness of Inquiry-Based Learning in an Undergraduate Exercise Physiology Course
Science.gov (United States)
Nybo, Lars; May, Michael
2015-01-01
The present study was conducted to investigate the effects of changing a laboratory physiology course for undergraduate students from a traditional step-by-step guided structure to an inquiry-based approach. With this aim in mind, quantitative and qualitative evaluations of learning outcomes (individual subject-specific tests and group interviews)…
10. A Biphasic Ligand Exchange Reaction on Cdse Nanoparticles: Introducing Undergraduates to Functionalizing Nanoparticles for Solar Cells
Science.gov (United States)
Zemke, Jennifer M.; Franz, Justin
2016-01-01
Semiconductor nanoparticles, including cadmium selenide (CdSe) particles, are attractive as light harvesting materials for solar cells. In the undergraduate laboratory, the size-tunable optical and electronic properties can be easily investigated; however, these nanoparticles (NPs) offer another platform for application-based tunability--the NP…
11. Using "Pseudomonas Putida xylE" Gene to Teach Molecular Cloning Techniques for Undergraduates
Science.gov (United States)
Dong, Xu; Xin, Yi; Ye, Li; Ma, Yufang
2009-01-01
We have developed and implemented a serial experiment in molecular cloning laboratory course for undergraduate students majored in biotechnology. "Pseudomonas putida xylE" gene, encoding catechol 2, 3-dioxygenase, was manipulated to learn molecular biology techniques. The integration of cloning, expression, and enzyme assay gave students…
12. A Course-Based Undergraduate Research Experience Investigating p300 Bromodomain Mutations
Science.gov (United States)
Shanle, Erin K.; Tsun, Ian K.; Strahl, Brian D.
2016-01-01
Course-based undergraduate research experiences (CUREs) provide an opportunity for students to engage in experiments with outcomes that are unknown to both the instructor and students. These experiences allow students and instructors to collaboratively bridge the research laboratory and classroom, and provide research experiences for a large…
13. Undergraduate Organic Experiment: Tetrazole Formation by Microwave Heated (3 + 2) Cycloaddition in Aqueous Solution
Science.gov (United States)
DeFrancesco, Heather; Dudley, Joshua; Coca, Adiel
2018-01-01
An undergraduate experiment for the organic laboratory is described that utilizes microwave heating to prepare 5- substituted 1H-tetrazole derivatives through a (3 + 2) cycloaddition between aryl nitriles and sodium azide. The reaction mixture is analyzed by thin layer chromatography. The products are purified through an acid-base extraction and…
14. Strategies for Using Peer-Assisted Learning Effectively in an Undergraduate Bioinformatics Course
Science.gov (United States)
Shapiro, Casey; Ayon, Carlos; Moberg-Parker, Jordan; Levis-Fitzgerald, Marc; Sanders, Erin R.
2013-01-01
This study used a mixed methods approach to evaluate hybrid peer-assisted learning approaches incorporated into a bioinformatics tutorial for a genome annotation research project. Quantitative and qualitative data were collected from undergraduates who enrolled in a research-based laboratory course during two different academic terms at UCLA.…
15. Integrating Scientific Argumentation to Improve Undergraduate Writing and Learning in a Global Environmental Change Course
Science.gov (United States)
Koffman, Bess G.; Kreutz,Karl J.; Trenbath, Kim
2017-01-01
We present a strategy for using scientific argumentation in an early undergraduate laboratory course to teach disciplinary writing practices and to promote critical thinking, knowledge transformation, and understanding of the scientific method. The approach combines targeted writing instruction; data analysis and interpretation; formulation of a…
16. The Python Project: A Unique Model for Extending Research Opportunities to Undergraduate Students
Science.gov (United States)
Harvey, Pamela A.; Wall, Christopher; Luckey, Stephen W.; Langer, Stephen; Leinwand, Leslie A.
2014-01-01
Undergraduate science education curricula are traditionally composed of didactic instruction with a small number of laboratory courses that provide introductory training in research techniques. Research on learning methodologies suggests this model is relatively ineffective, whereas participation in independent research projects promotes enhanced…
17. [Art in undergraduate medical education].
Science.gov (United States)
Fjellstad, Kenneth; Isaksen, Tor Olav; Frich, Jan C
2003-08-28
During the last decades attempts have been made at integrating art in medical education. What should be the form, content and objectives of such teaching? We address this question on the basis of a review of articles in medical journals from 1990 until May 2001 about art and undergraduate medical education. A common reason for integrating art in undergraduate medical education is that art may act as a balance to the dominance of natural science. One pedagogical approach is to use art as a tool for training skills. Many articles emphasise that teaching art should also contribute to the personal and professional development of medical students. The majority of articles report on courses in literature and medicine. Art is often taught in small or medium-sized groups; courses may last from single lessons to programmes over years. The aim of art courses may be the development of skills, but also one of facilitating personal growth and professional development.
18. Thermodynamics a complete undergraduate course
CERN Document Server
Steane, Andrew M
2016-01-01
This is an undergraduate textbook in thermodynamics—the science of heat, work, temperature, and entropy. The text presents thermodynamics in and of itself, as an elegant and powerful set of ideas and methods. These methods open the way to understanding a very wide range of phenomena in physics, chemistry, engineering, and biology. Starting out from an introduction of concepts at first year undergraduate level, the roles of temperature, internal energy, and entropy are explained via the laws of thermodynamics. The text employs a combination of examples, exercises, and careful discussion, with a view to conveying the feel of the subject as well as avoiding common misunderstandings. The Feynman–Smuluchowski ratchet, Szilard’s engine, and Maxwell’s daemon are used to elucidate entropy and the second law. Free energy and thermodynamic potentials are discussed at length, with applications to solids as well as fluids and flow processes. Thermal radiation is discussed, and the main ideas significant to global...
19. A Virtual PV Systems Lab for Engineering Undergraduate Curriculum
Directory of Open Access Journals (Sweden)
Emre Ozkop
2014-01-01
20. Saxton Transportation Operations Laboratory
Data.gov (United States)
Federal Laboratory Consortium — The Saxton Transportation Operations Laboratory (Saxton Laboratory) is a state-of-the-art facility for conducting transportation operations research. The laboratory...
1. Laboratory investigations
International Nuclear Information System (INIS)
Handin, J.
1980-01-01
Our task is to design mined-repository systems that will adequately secure high-level nuclear waste for at least 10,000 yr and that will be mechanically stable for 50 to 100-yr periods of retrievability during which mistakes could be corrected and a valuable source of energy could be reclaimed, should national policy on the reprocessing of spent fuel ever change. The only credible path for the escape of radionuclides from the repository to the biosphere is through ground-water, and in hard rock, bulk permeability is largely governed by natural and artificial fracture systems. Catastrophic failure of an excavation in hard rock is likely to occur at the weakest links - the discontinuities in the rock mass that is perturbed first by mining and then by radiogenic heating. The laboratory can contribute precise measurements of the pertinent thermomechanical, hydrological and chemical properties and improve our understanding of the fundamental processes through careful experiments under well controlled conditions that simulate the prototype environment. Thus laboratory investigations are necessary, but they are not sufficient, for conventional sample sizes are small relative to natural defects like joints - i.e., the rock mass is not a continuum - and test durations are short compared to those that predictive modeling must take into account. Laboratory investigators can contribute substantially more useful data if they are provided facilities for testing large specimens(say one cubic meter) and for creep testing of all candidate host rocks. Even so, extrapolations of laboratory data to the field in neither space nor time are valid without the firm theoretical foundations yet to be built. Meanwhile in-situ measurements of structure-sensitive physical properties and access to direct observations of rock-mass character will be absolutely necessary
2. Culham Laboratory
International Nuclear Information System (INIS)
1980-06-01
The report contains summaries of work carried out under the following headings: fusion research experiments; U.K. contribution to the JET project; supporting studies; theoretical plasma physics, computational physics and computing; fusion reactor studies; engineering and technology; contract research; external relations; staff, finance and services. Appendices cover main characteristics of Culham fusion experiments, staff, extra-mural projects supported by Culham Laboratory, and a list of papers written by Culham staff. (U.K.)
3. Plating laboratory
International Nuclear Information System (INIS)
Seamster, A.G.; Weitkamp, W.G.
1984-01-01
The lead plating of the prototype resonator has been conducted entirely in the plating laboratory at SUNY Stony Brook. Because of the considerable cost and inconvenience in transporting personnel and materials to and from Stony Brook, it is clearly impractical to plate all the resonators there. Furthermore, the high-beta resonator cannot be accommodated at Stony Brook without modifying the set up there. Consequently the authors are constructing a plating lab in-house
4. Engineering acoustics: A pioneer undergraduate program at Rio de Janeiro
Science.gov (United States)
Tenenbaum, Roberto A.; Zindeluk, Moyses
2002-11-01
Acoustics, essentially a multidisciplinary subject, still has in Brazil a small but increasing number of professionals with a solid background to deal with various aspects of this area. Since 1970 the faculty of the Acoustics and Vibration Laboratory, COPPE/UFRJ, offers graduate (M.Sc and D.Sc) programs, and some undergraduate courses in acoustics, vibration, and signal processing. In January 2000, this group launched a formal undergraduate engineering acoustics program in the Mechanical Engineering Department of the Federal University of Rio de Janeiro. After three years of mechanical engineering, with a firm foundation in physics, applied mathematics, and engineering basics, the undergraduate student may elect to take the engineering acoustics program for the remaining two years. In this program, a wide number of courses are offered, including basic acoustics, room acoustics, signal processing, musical acoustics, machine diagnosis, etc. Approximately 30 different courses may be chosen from. However, the student is not completely free, since the courses selected must fit within a subject concentration profile, e.g., noise control or musical acoustics. In this paper the programs curriculum are presented and its impact on the students is discussed. A first evaluation of the qualifications achieved by the graduate students in the area is also presented.
5. Pattern of Smartphones Utilisation among Engineering Undergraduates
OpenAIRE
Muliati Sedek
2014-01-01
The smartphones ownership among the undergraduates in Malaysia was recorded as high. However, little was known about its utilization patterns, thus, the focus of this research was to determine the utilisation patterns of smartphones based on the National Education Technology Standard for Students (NETS.S) among engineering undergraduates in Malaysia. This study was based on a quantitative research and the population comprised undergraduates from four Malaysian Technical Universities. A total ...
6. Undergraduate Breakfast, Career Workshop, and Awards
Science.gov (United States)
2017-01-01
Undergraduate students can enjoy a hearty breakfast and learn about how to prepare for a wide variety of careers in physics outside of academia. Topics of this interactive workshop will include planning and self-assessment, inventorying transferable skills, finding out more about career opportunities, and successfully applying for jobs. Immediately following the workshop, top presenters from the Undergraduate Research/SPS sessions will be recognized. All presenters in the undergraduate sessions will receive certificates acknowledging their scientific accomplishments.
7. Motivation of first semester undergraduate students
DEFF Research Database (Denmark)
Schlichter, Bjarne; Sigvardsen, Kari; Jonsson, Sofia
Purpose - The importance and development of information systems are increasing, so are the need of business students' general understanding of information systems and the function of these in businesses as well as influence on firms’ competitiveness. The aim of this study was to identify first year...... of first semester undergraduate students. Keywords -Motivation; first year undergraduate students; Management Information Systems; teaching assistants. Paper type - Research paper....... undergraduate students’ motivation and commitment towards education regarding management information system, and how student teaching assistants' attitude and qualities influence these factors. The paper is based on a case study of first year undergraduate students taking the course IT in Business as part...
8. Use of Smartphones With Undergraduate Nursing Students.
Science.gov (United States)
George, Tracy P; DeCristofaro, Claire
2016-07-01
It is important for nursing students to become comfortable with accessing point-of-care technology to support provision of safe, evidence-based care to patients. Smartphone applications (apps) were introduced into community screening settings in a first-semester undergraduate nursing health assessment course. The apps provided information about body mass index, as well as United States Preventive Services Task Force-recommended preventive services using the Agency for Health Research and Quality electronic preventive services selector app. Classroom activities prepared students using mock cases and real data, and evidence-based guidelines were used when counseling patients about individual results. Smartphone apps were well accepted by students and allowed students to transfer learning from the classroom and laboratory to the community setting. Smartphone apps promote active learning and the long-term retention of knowledge. This community-based activity supports the validity of independent health promotion activities in nursing practice. [J Nurs Educ. 2016;55(7):411-415.]. Copyright 2016, SLACK Incorporated.
9. A Parametric Oscillator Experiment for Undergraduates
Science.gov (United States)
Huff, Alison; Thompson, Johnathon; Pate, Jacob; Kim, Hannah; Chiao, Raymond; Sharping, Jay
We describe an upper-division undergraduate-level analytic mechanics experiment or classroom demonstration of a weakly-damped pendulum driven into parametric resonance. Students can derive the equations of motion from first principles and extract key oscillator features, such as quality factor and parametric gain, from experimental data. The apparatus is compact, portable and easily constructed from inexpensive components. Motion control and data acquisition are accomplished using an Arduino micro-controller incorporating a servo motor, laser sensor, and data logger. We record the passage time of the pendulum through its equilibrium position and obtain the maximum speed per oscillation as a function of time. As examples of the interesting physics which the experiment reveals, we present contour plots depicting the energy of the system as functions of driven frequency and modulation depth. We observe the transition to steady state oscillation and compare the experimental oscillation threshold with theoretical expectations. A thorough understanding of this hands-on laboratory exercise provides a foundation for current research in quantum information and opto-mechanics, where damped harmonic motion, quality factor, and parametric amplification are central.
10. Gene Amplification by PCR and Subcloning into a GFP-Fusion Plasmid Expression Vector as a Molecular Biology Laboratory Course
Science.gov (United States)
Bornhorst, Joshua A.; Deibel, Michael A.; Mulnix, Amy B.
2004-01-01
A novel experimental sequence for the advanced undergraduate laboratory course has been developed at Earlham College. Utilizing recent improvements in molecular techniques for a time-sensitive environment, undergraduates were able to create a chimera of a selected gene and green fluorescent protein (GFP) in a bacterial expression plasmid over the…
11. Synthesis and Metalation of a Ligand: An Interdisciplinary Laboratory Experiment for Second-Year Organic and Introductory Inorganic Chemistry Students
Science.gov (United States)
Kasting, Benjamin J.; Bowser, Andrew K.; Anderson-Wile, Amelia M.; Wile, Bradley M.
2015-01-01
An interdisciplinary laboratory experiment involving second-year undergraduate organic chemistry and introductory inorganic chemistry undergraduate students is described. Organic chemistry students prepare a series of amine-bis(phenols) via a Mannich reaction, and characterize their products using melting point; FTIR; and [superscript 1]H,…
12. Bridging the Gap between Instructional and Research Laboratories: Teaching Data Analysis Software Skills through the Manipulation of Original Research Data
Science.gov (United States)
Hansen, Sarah J. R.; Zhu, Jieling; Karch, Jessica M.; Sorrento, Cristina M.; Ulichny, Joseph C.; Kaufman, Laura J.
2016-01-01
The gap between graduate research and introductory undergraduate teaching laboratories is often wide, but the development of teaching activities rooted within the research environment offers an opportunity for undergraduate students to have first-hand experience with research currently being conducted and for graduate students to develop…
13. Laboratory exercises on oscillation modes of pipes
Science.gov (United States)
Haeberli, Willy
2009-03-01
This paper describes an improved lab setup to study the vibrations of air columns in pipes. Features of the setup include transparent pipes which reveal the position of a movable microphone inside the pipe; excitation of pipe modes with a miniature microphone placed to allow access to the microphone stem for open, closed, or conical pipes; and sound insulation to avoid interference between different setups in a student lab. The suggested experiments on the modes of open, closed, and conical pipes, the transient response of a pipe, and the effect of pipe diameter are suitable for introductory physics laboratories, including laboratories for nonscience majors and music students, and for more advanced undergraduate laboratories. For honors students or for advanced laboratory exercises, the quantitative relation between the resonance width and damping time constant is of interest.
14. Undergraduate topology a working textbook
CERN Document Server
McCluskey, Aisling
2014-01-01
This textbook offers an accessible, modern introduction at undergraduate level to an area known variously as general topology, point-set topology or analytic topology with a particular focus on helping students to build theory for themselves. It is the result of several years of the authors' combined university teaching experience stimulated by sustained interest in advanced mathematical thinking and learning, alongside established research careers in analytic topology. Point-set topology is a discipline that needs relatively little background knowledge, but sufficient determination to grasp i
15. Teaching undergraduate astrophysics with PIRATE
Science.gov (United States)
Brodeur, M. S.; Kolb, U.; Minocha, S.; Braithwaite, N.
2014-12-01
PIRATE is a 0.43m semi-autonomous research and teaching observatory owned by The Open University, UK. Since 2010, it has been reserved for several months of each year for teaching astronomy in the OU's undergraduate programme. As students in these courses operate PIRATE remotely rather than travelling to the observatory itself, we chose to investigate whether effective learning was adversely affected by the absence of a more traditional hands on' experience. We discuss student perspectives on the technologies employed (i.e., remote and virtual investigations), the impact these had on perceived course outcomes, and consider implications for future teaching and outreach.
16. Mechanics problems in undergraduate physics
CERN Document Server
Strelkov, S P
2013-01-01
Problems in Undergraduate Physics, Volume I: Mechanics focuses on solutions to problems in physics. The book first discusses the fundamental problems in physics. Topics include laws of conservation of momentum and energy; dynamics of a point particle in circular motion; dynamics of a rotating rigid body; hydrostatics and aerostatics; and acoustics. The text also offers information on solutions to problems in physics. Answers to problems in kinematics, statics, gravity, elastic deformations, vibrations, and hydrostatics and aerostatics are discussed. Solutions to problems related to the laws of
17. Integrating Interdisciplinary Research-Based Experiences in Biotechnology Laboratories
Science.gov (United States)
Iyer, Rupa S.; Wales, Melinda E.
2012-01-01
The increasingly interdisciplinary nature of today's scientific research is leading to the transformation of undergraduate education. In addressing these needs, the University of Houston's College of Technology has developed a new interdisciplinary research-based biotechnology laboratory curriculum. Using the pesticide degrading bacterium,…
18. Differentiating Biochemistry Course Laboratories Based on Student Experience
Science.gov (United States)
Jakubowski, Henry V.
2011-01-01
Content and emphases in undergraduate biochemistry courses can be readily tailored to accommodate the standards of the department in which they are housed, as well as the backgrounds of the students in the courses. A more challenging issue is how to construct laboratory experiences for a class with both chemistry majors, who usually have little or…
19. Development of a Green Fluorescent Protein-Based Laboratory Curriculum
Science.gov (United States)
Larkin, Patrick D.; Hartberg, Yasha
2005-01-01
A laboratory curriculum has been designed for an undergraduate biochemistry course that focuses on the investigation of the green fluorescent protein (GFP). The sequence of procedures extends from analysis of the DNA sequence through PCR amplification, recombinant plasmid DNA synthesis, bacterial transformation, expression, isolation, and…
20. Women's Experiences in the Engineering Laboratory in Japan
Science.gov (United States)
Hosaka, Masako
2014-01-01
This qualitative study aims to examine Japanese women undergraduate engineering students' experiences of interacting with departmental peers of the same year in the laboratory setting by using interview data of 32 final-year students at two modestly selective national universities in Japan. Expectation state theory that explains unequal…
1. An Automated Distillation Column for the Unit Operations Laboratory
Science.gov (United States)
Perkins, Douglas M.; Bruce, David A.; Gooding, Charles H.; Butler, Justin T.
2005-01-01
A batch distillation apparatus has been designed and built for use in the undergraduate unit operations laboratory course. The column is fully automated and is accompanied by data acquisition and control software. A mixture of 1-propanol and 2-propanol is separated in the column, using either a constant distillate rate or constant composition…
2. Community-Based Presentations in the Unit Operations Laboratory
Science.gov (United States)
Mitchell, Brian S.; Law, Victor J.
2005-01-01
A method for incorporating community-based oral presentations into the undergraduate chemical engineering unit operations laboratory experience is described. Examples are given of appropriate topics and how these presentations can be incorporated into the experiment sequence. Course evaluations reflect the fact that these presentations are an…
3. Managing Laboratory Data Using Cloud Computing as an Organizational Tool
Science.gov (United States)
Bennett, Jacqueline; Pence, Harry E.
2011-01-01
One of the most significant difficulties encountered when directing undergraduate research and developing new laboratory experiments is how to efficiently manage the data generated by a number of students. Cloud computing, where both software and computer files reside online, offers a solution to this data-management problem and allows researchers…
4. Observing Animal Behavior at the Zoo: A Learning Laboratory
Science.gov (United States)
Hull, Debra B.
2003-01-01
Undergraduate students in a learning laboratory course initially chose a species to study; researched that species' physical and behavioral characteristics; then learned skills necessary to select, operationalize, observe, and record animal behavior accurately. After their classroom preparation, students went to a local zoo to observe the behavior…
5. Suitability for 3D Printed Parts for Laboratory Use
Energy Technology Data Exchange (ETDEWEB)
Zwicker, Andrew P. [PPPL; Bloom, Josh [PPPL; Albertson, Robert [PPPL; Gershman, Sophia [PPPL
2014-08-01
3D printing has become popular for a variety of users, from industrial to the home hobbyist, to scientists and engineers interested in producing their own laboratory equipment. In order to determine the suitability of 3D printed parts for our plasma physics laboratory, we measured the accuracy, strength, vacuum compatibility, and electrical properties of pieces printed in plastic. The flexibility of rapidly creating custom parts has led to the 3D printer becoming an invaluable resource in our laboratory and is equally suitable for producing equipment for advanced undergraduate laboratories.
6. Undergraduate Research as Engaged Student Learning
Science.gov (United States)
Wolf, Lorraine W.
2018-01-01
This chapter discusses the impact of undergraduate research as a form of engaged student learning. It summarizes the gains reported in post-fellowship assessment essays acquired from students participating in the Auburn University Undergraduate Research Fellowship Program. The chapter also discusses the program's efforts to increase opportunities…
7. Imitation in Undergraduate Teaching and Learning
Science.gov (United States)
Zhou, Jiangyuan; Guo, Wei
2016-01-01
Research in developmental psychology and neuroscience has demonstrated the critical role of imitation in human learning. Self-report questionnaires collected from 456 undergraduate students in two U.S. institutions and one Chinese institution demonstrated that undergraduate students from both U.S. and Chinese cultures used various imitations in…
8. Early undergraduate research experience at Makerere University ...
African Journals Online (AJOL)
To remain relevant the Faculty of Medicine Makerere University needs to identify research enhancing opportunities like undergraduate research experiences. Methods: This was a cross sectional study involving 424 graduate and undergraduate students of Makerere University Medical School on the traditional curriculum.
9. Undergraduate Women's Persistence in the Sciences
Science.gov (United States)
George-Jackson, Casey E.
2014-01-01
This study uses longitudinal data of undergraduate students from five public land-grant universities to better understand undergraduate students' persistence in and switching of majors, with particular attention given to women's participation in science, technology, engineering, and mathematics (STEM) fields. Specifically, the study examines…
African Journals Online (AJOL)
The study examined the influence of internet usage on academic performance of undergraduate students of the University ofIlorin, Nigeria.This study adopted descriptive survey method. Six faculties were randomly selected from the 13 faculties in the University while 200 undergraduate students were sampled across these ...
11. Undergraduates Perspectives on Sex Education and Teenage ...
African Journals Online (AJOL)
This study examines undergraduates' perspective on sex education and teenage pregnancy in Covenant University, Ota, Ogun State, Nigeria. The study population was 250 undergraduates of Covenant University. Frequency tables, linear regression analysis and analysis of variance were used to analyze the data collected ...
12. Students' perspectives of undergraduate research methods ...
African Journals Online (AJOL)
Introduction: in this study we used a model of adult learning to explore undergraduate students' views on how to improve the teaching of research methods and biostatistics. Methods: this was a secondary analysis of survey data of 600 undergraduate students from three medical schools in Uganda. The analysis looked at ...
13. Lecturers' Views on Ghana's Undergraduate Mathematics Education
Science.gov (United States)
Assuah, Charles; Ayebo, Abraham
2015-01-01
This paper synthesizes the views of 6 university lecturers on Ghana's undergraduate mathematics education. These views were expressed during a mathematics workshop sensitization program on the "contribution of undergraduate mathematics education to the Ghanaian economy." The data consisting of open-ended questions followed by…
14. Social Work Faculty and Undergraduate Research Mentorships
Science.gov (United States)
Horner, Pilar S.; Hughes, Anne K.; Vélez Ortiz, Daniel
2016-01-01
Social work faculty scholars lead the field as generators of knowledge that integrates investigative studies with practical social welfare outcomes. As such, the faculty potentially offers undergraduate researchers a different way of envisioning research that extends beyond traditional undergraduate research models. To date, however, no research…
15. Applications of AViz in Undergraduate Education
Science.gov (United States)
Animated visualizations of physical systems can help undergraduate students understand and even enjoy their Physics classes. Preparing such visualizations provides interesting projects for senior undergraduate and graduate students, who learn basic techniques of computer simulation on systems that are relatively easy for them to understand.
16. Agriculture Undergraduates Preference For Agriculture Disciplines ...
African Journals Online (AJOL)
The broad objective of this study research is to investigate the preferences for the different disciplines in agriculture by undergraduate students of Agriculture with a view to understanding the effect on future manpower needs in Nigerian agriculture. Data for the study were collected from 99 randomly selected undergraduate ...
17. Undergraduate Research in the Dartmouth Economics Department
Science.gov (United States)
Feyrer, James
2017-01-01
One of the key components to the undergraduate research enterprise at Dartmouth is the recognition that learning to do research requires both directed instruction and learning by doing. The economics faculty have tailored a fruitful undergraduate research program based on this philosophy, and this article describes these efforts while also…
18. An Undergraduate, Interdisciplinary Program in Gerontology.
Science.gov (United States)
Puglisi, J. Thomas
The program development project described in this report was undertaken at the University of North Carolina at Charlotte to develop faculty expertise and experience in undergraduate teaching in gerontology and to lay the foundation for an interdisciplinary, undergraduate minor in gerontology. Three core courses for the minor in gerontology were…
19. Research: Clinical undergraduate medical student training at ...
African Journals Online (AJOL)
To profile the clinicians at Kimberley Hospital Complex in terms of their knowledge of, skills in and perspectives on the added responsibility of clinical undergraduate medical student training prior to the launch of the proposed undergraduate student rotations. Methods. The study followed a qualitative research design using ...
20. Joint hypermobility syndrome among undergraduate students | Didia ...
African Journals Online (AJOL)
Objective: To assess the prevalence of joint hypermobility syndrome among undergraduate students of the University of Port Harcourt, Nigeria using the Beighton's criteria. Design: Cross- sectional prospective study of 550 randomly selected undergraduate students . Setting: Departments of Anatomy and Human Physiology ...
1. Prevalence and Severity of Depression among Undergraduate ...
African Journals Online (AJOL)
Purpose: To highlight the prevalence and severity of depression among undergraduate students in public and private ... mental health effect of university education on undergraduate students, especially female students. Keywords: Depression ..... Kim YS, Koh YJ, Leventhal B. School bullying and suicidal risk in Korean ...
2. Journal of Undergraduate Research, Volume VIII, 2008
Energy Technology Data Exchange (ETDEWEB)
Stiner, K. S.; Graham, S.; Khan, M.; Dilks, J.; Mayer, D.
2008-01-01
Th e Journal of Undergraduate Research (JUR) provides undergraduate interns the opportunity to publish their scientific innovation and to share their passion for education and research with fellow students and scientists. Fields in which these students worked include: Biology; Chemistry; Computer Science; Engineering; Environmental Science; General Sciences; Materials Sciences; Medical and Health Sciences; Nuclear Sciences; Physics; Science Policy; and Waste Management.
3. Undergraduate Single Mothers' Experiences in Postsecondary Education
Science.gov (United States)
Beeler, Sydney
2016-01-01
Using Astin's (1993) College Impact Model, this chapter explores the current literature as it relates to single mothers in undergraduate postsecondary education. The chapter looks at the ways that undergraduates who are single mothers are counter to the "ideal-student" norms. Policy and best-practice recommendations conclude the chapter.
4. Undergraduate Research Mentoring: Obstacles and Opportunities
Science.gov (United States)
Johnson, W. Brad; Behling, Laura L.; Miller, Paul; Vandermaas-Peeler, Maureen
2015-01-01
Researchers and policy-makers in higher education increasingly espouse the view that undergraduate students should have the opportunity to learn about scholarship and research in the context of faculty-mentored research experiences. There is mounting consensus that mentored undergraduate research should be standard pedagogical practice in all…
5. A Review of Undergraduate Mentoring Programs
Science.gov (United States)
Gershenfeld, Susan
2014-01-01
This review summarizes published studies on undergraduate mentoring programs from 2008 to 2012. Twenty studies met the inclusion criteria, which included empirical research on formal mentoring programs with undergraduate students as mentees or mentors. Each study was assessed based on limitations identified in two earlier reviews of the mentoring…
6. Undergraduate International Studies and Foreign Language Program
Science.gov (United States)
Office of Postsecondary Education, US Department of Education, 2012
2012-01-01
The Undergraduate International Studies and Foreign Language Program provides funds to institutions of higher education, a consortia of such institutions, or partnerships between nonprofit organizations and institutions of higher education to plan, develop, and implement programs that strengthen and improve undergraduate instruction in…
7. Causes of Sexual Promiscuity Among Female Undergraduate ...
African Journals Online (AJOL)
This study investigated causes of sexual promiscuity among female undergraduate students in university of Lagos. The sample comprised 150 female undergraduate students randomly selected from all the five female hostels in University of Lagos. A researcher-constructed questionnaire was administered to test the three ...
Science.gov (United States)
Westrick, Paul A.
2017-01-01
Undergraduate grade point average (GPA) is a commonly employed measure in educational research, serving as a criterion or as a predictor depending on the research question. Over the decades, researchers have used a variety of reliability coefficients to estimate the reliability of undergraduate GPA, which suggests that there has been no consensus…
9. The undergraduate optics course at Millersville University
Science.gov (United States)
Gilani, Tariq H.; Dushkina, Natalia M.
2009-06-01
For many years, there was no stand alone course in optics at Millersville University (MU). In the fall of 2007, the Physics Department offered for the first time PHYS 331: Fundamentals in Optics, a discovery based lab course in geometrical, physical and modern optics. This 300-level, 2 credits course consists of four contact hours per week including one-hour lecture and three hours laboratory. This course is required for BS in physics majors, but is open also to other science majors, who have the appropriate background and have met the prerequisites. This course deals with fundamental optics and optical techniques in greater depth so that the student is abreast of the activities in the forefront of the field. The goal of the course is to provide hands-on experience and in-depth preparation of our students for graduate programs in optics or as a workforce for new emerging high-tech local industries. Students learn applied optics through sequence of discovery based laboratory experiments chosen from a broad range of topics in optics and lasers, as the emphasis is on geometrical optics, geometrical aberrations in optical systems, wave optics, microscopy, spectroscopy, polarization, birefringence, laser generation, laser properties and applications, and optical standards. The peer-guided but open-ended approach provides excellent practice for the academic model of science research. Solving problems is embedded in the laboratory part as an introduction to or a conclusion of the experiment performed during the lab period. The homework problems are carefully chosen to reflect the most important relations from the covered material. Important part of the student learning strategy is the individual work on a final mini project which is presented in the class and is included in the final grading. This new course also impacted the department's undergraduate research and training programs. Some of the individual projects were extended to senior research projects in optics as
10. Tested Studies for Laboratory Teaching. Proceedings of the Workshop/Conference of the Association for Biology Laboratory Education (ABLE) (5th, Clemson, South Carolina, June 13-17, 1983).
Science.gov (United States)
Goldman, Corey A., Ed.; And Others
The focus of the Association for Biology Laboratory Education (ABLE) is to improve the undergraduate biology laboratory experience by promoting the development and dissemination of interesting, innovative, and reliable laboratory exercises. This proceedings volume contains eight papers: "Bacterial Transformation" (M. J. Ernest & N. J. Rosenbaum);…
11. Tested Studies for Laboratory Teaching. Proceedings of the Workshop/Conference of the Association for Biology Laboratory Education (ABLE) (15th, Toronto, Ontario, Canada, June 8-12, 1993). Volume 15.
Science.gov (United States)
Goldman, Corey A., Ed.
The focus of the Association for Biology Laboratory Education (ABLE) is to improve the undergraduate biology laboratory experience by promoting the development and dissemination of interesting, innovative, and reliable laboratory exercises. This proceedings volume contains 18 papers: "Human DNA Fingerprinting by Polymerase Chain Reaction" (M. V.…
12. Tested Studies for Laboratory Teaching. Proceedings of the Workshop/Conference of the Association for Biology Laboratory Education (ABLE) (13th, Laramie, Wyoming, June 11-15, 1991). Volume 13.
Science.gov (United States)
Goldman, Corey A., Ed.
The focus of the Association for Biology Laboratory Education (ABLE) is to improve the undergraduate biology laboratory experience by promoting the development and dissemination of interesting, innovative, and reliable laboratory exercises. This proceedings volume contains 10 papers: "Testing Issues of Foraging and Flocking Behavior" (C. C.…
13. Uncovering protein-protein interactions through a team-based undergraduate biochemistry course.
Science.gov (United States)
Cookmeyer, David L; Winesett, Emily S; Kokona, Bashkim; Huff, Adam R; Aliev, Sabina; Bloch, Noah B; Bulos, Joshua A; Evans, Irene L; Fagre, Christian R; Godbe, Kerilyn N; Khromava, Maryna; Konstantinovsky, Daniel M; Lafrance, Alexander E; Lamacki, Alexandra J; Parry, Robert C; Quinn, Jeanne M; Thurston, Alana M; Tsai, Kathleen J S; Mollo, Aurelio; Cryle, Max J; Fairman, Robert; Charkoudian, Louise K
2017-11-01
How can we provide fertile ground for students to simultaneously explore a breadth of foundational knowledge, develop cross-disciplinary problem-solving skills, gain resiliency, and learn to work as a member of a team? One way is to integrate original research in the context of an undergraduate biochemistry course. In this Community Page, we discuss the development and execution of an interdisciplinary and cross-departmental undergraduate biochemistry laboratory course. We present a template for how a similar course can be replicated at other institutions and provide pedagogical and research results from a sample module in which we challenged our students to study the binding interface between 2 important biosynthetic proteins. Finally, we address the community and invite others to join us in making a larger impact on undergraduate education and the field of biochemistry by coordinating efforts to integrate research and teaching across campuses.
14. Uncovering protein-protein interactions through a team-based undergraduate biochemistry course.
Directory of Open Access Journals (Sweden)
David L Cookmeyer
2017-11-01
Full Text Available How can we provide fertile ground for students to simultaneously explore a breadth of foundational knowledge, develop cross-disciplinary problem-solving skills, gain resiliency, and learn to work as a member of a team? One way is to integrate original research in the context of an undergraduate biochemistry course. In this Community Page, we discuss the development and execution of an interdisciplinary and cross-departmental undergraduate biochemistry laboratory course. We present a template for how a similar course can be replicated at other institutions and provide pedagogical and research results from a sample module in which we challenged our students to study the binding interface between 2 important biosynthetic proteins. Finally, we address the community and invite others to join us in making a larger impact on undergraduate education and the field of biochemistry by coordinating efforts to integrate research and teaching across campuses.
15. Uncovering protein–protein interactions through a team-based undergraduate biochemistry course
Science.gov (United States)
Cookmeyer, David L.; Winesett, Emily S.; Kokona, Bashkim; Huff, Adam R.; Aliev, Sabina; Bloch, Noah B.; Bulos, Joshua A.; Evans, Irene L.; Fagre, Christian R.; Godbe, Kerilyn N.; Khromava, Maryna; Konstantinovsky, Daniel M.; Lafrance, Alexander E.; Lamacki, Alexandra J.; Parry, Robert C.; Quinn, Jeanne M.; Thurston, Alana M.; Tsai, Kathleen J. S.; Mollo, Aurelio; Cryle, Max J.; Fairman, Robert
2017-01-01
How can we provide fertile ground for students to simultaneously explore a breadth of foundational knowledge, develop cross-disciplinary problem-solving skills, gain resiliency, and learn to work as a member of a team? One way is to integrate original research in the context of an undergraduate biochemistry course. In this Community Page, we discuss the development and execution of an interdisciplinary and cross-departmental undergraduate biochemistry laboratory course. We present a template for how a similar course can be replicated at other institutions and provide pedagogical and research results from a sample module in which we challenged our students to study the binding interface between 2 important biosynthetic proteins. Finally, we address the community and invite others to join us in making a larger impact on undergraduate education and the field of biochemistry by coordinating efforts to integrate research and teaching across campuses. PMID:29091712
16. Brownian motion - a laboratory experiment
Science.gov (United States)
Kruglak, Haym
1988-09-01
The availability of latex microspheres, compact television cameras and electronic calculators make it possible to perform an experiment on Brownian movement in one laboratory period. A more accurate value of N can be determined by other methods. However, the experiment described above has several valuable pedagogical outcomes. Undergraduate students get experience with several experimental techniques: (i) recording a random walk' of a microphere; (ii) plotting a histogram of displacements; (iii) fitting a Gaussian curve to the histogram; (iv) checking the goodness of fit analytically or with probability graph paper; (v) calibrating screen displacements with a diffraction grating; (vi) calculating Avogadro's number from the experimental data; (vii) verifying data validity with the Einstein - Smoluchowski Law. The experiment also provides valuable practice in unit conversion and error analysis. Another instructive feature: the experiment makes the students aware of Einstein's work other than relativity. The students' reactions to the experiment were positive: interesting', challenging', `fun'.
17. Elevating Learner Achievement Using Formative Electronic Lab Assessments in the Engineering Laboratory: A Viable Alternative to Weekly Lab Reports
Science.gov (United States)
Chen, Baiyun; DeMara, Ronald F.; Salehi, Soheil; Hartshorne, Richard
2018-01-01
A laboratory pedagogy interweaving weekly student portfolios with onsite formative electronic laboratory assessments (ELAs) is developed and assessed within the laboratory component of a required core course of the electrical and computer engineering (ECE) undergraduate curriculum. The approach acts to promote student outcomes, and neutralize…
18. Using Yeast to Determine the Functional Consequences of Mutations in the Human p53 Tumor Suppressor Gene: An Introductory Course-Based Undergraduate Research Experience in Molecular and Cell Biology
Science.gov (United States)
Hekmat-Scafe, Daria S.; Brownell, Sara E.; Seawell, Patricia Chandler; Malladi, Shyamala; Imam, Jamie F. Conklin; Singla, Veena; Bradon, Nicole; Cyert, Martha S.; Stearns, Tim
2017-01-01
The opportunity to engage in scientific research is an important, but often neglected, component of undergraduate training in biology. We describe the curriculum for an innovative, course-based undergraduate research experience (CURE) appropriate for a large, introductory cell and molecular biology laboratory class that leverages students' high…
19. An ET-CURE pilot project supporting undergraduate training in cancer research, emerging technology, and health disparities.
Science.gov (United States)
Wilson, Danyell S; Fang, Bin; Dalton, William S; Meade, Cathy D; Koomen, John M
2012-06-01
The National Cancer Institute's Center to Reduce Cancer Health Disparities has created pilot training opportunities under the "Continuing Umbrella of Research Experiences" program that focus on emerging technologies. In this pilot project, an 18-month cancer biology research internship was reinforced with: instruction in an emerging technology (proteomics), a transition from the undergraduate laboratory to a research setting, education in cancer health disparities, and community outreach activities. A major goal was to provide underrepresented undergraduates with hands-on research experiences that are rarely encountered at the undergraduate level, including mentoring, research presentations, and participation in local and national meetings. These opportunities provided education and career development for the undergraduates, and they have given each student the opportunity to transition from learning to sharing their knowledge and from being mentored to mentoring others. Here, we present the concepts, curriculum, infrastructure, and challenges for this training program along with evaluations by both the students and their mentors.
20. Synthesizing Novel Anthraquinone Natural Product-Like Compounds to Investigate Protein-Ligand Interactions in Both an in Vitro and in Vivo Assay: An Integrated Research-Based Third-Year Chemical Biology Laboratory Course
Science.gov (United States)
McKenzie, Nancy; McNulty, James; McLeod, David; McFadden, Meghan; Balachandran, Naresh
2012-01-01
A new undergraduate program in chemical biology was launched in 2008 to provide a unique learning experience for those students interested in this interdisciplinary science. An innovative undergraduate chemical biology laboratory course at the third-year level was developed as a key component of the curriculum. The laboratory course introduces… | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 1, "mathjax_display_tex": 0, "mathjax_asciimath": 1, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.4855005443096161, "perplexity": 6953.766315929661}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2018-26/segments/1529267860684.14/warc/CC-MAIN-20180618164208-20180618184208-00252.warc.gz"} |
https://aviation.stackexchange.com/questions/23560/how-do-gyroscopic-instruments-work/23561 | # How do gyroscopic instruments work? [closed]
I'm trying to better my understanding of the physics behind gyroscopic instruments in an aircraft. I am aware that a spinning gyroscope creates rigidity in space by resisting applied forces. But, what exactly is the resistive force acting on the externally applied to forces, and how is it created? Is that what precession is?
• I'm voting to close this question as off-topic. This question would be better on Physics.SE The answer is inertia in the spinning plan (conservation of angular momentum).
– mins
Dec 10 '15 at 6:32
• Yeah your probably right. Didn't cross my mind, I just came straight here. Dec 10 '15 at 6:36
I saw this pretty cool video a while ago:
It gives an intuitive discussion of gyroscopes.
On another level though, it boils down to the angular momentum of the spinning gyroscope, and the fact that in order to change that momentum's direction/magnitude, an external moment must be applied.
Gyroscopes basically work by the principle of conservation of angular momentum. Consider a gyroscope (or a spinning wheel) in space like shown below:
Image from pigeonsnest.co.uk
Consider the wheel in the center spinning at an angular velocity $\omega$, so that the spin angular momentum is $I\omega$, along the X axis. Now, consider a torque applied $\mathcal{T}$ along the Z axis.
Now, the resultant of these two makes the spin axis to align along the axis A'. Basically, the spin angular momentum 'chases' the torque in the same plane. This is the basis of gyroscopic precession.
See Prof. Walter Lewin's lecture on Rolling motion and gyroscopes for a thorough explanation. | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 1, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.9199215769767761, "perplexity": 669.7865985338144}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2021-39/segments/1631780057199.49/warc/CC-MAIN-20210921070944-20210921100944-00529.warc.gz"} |
https://www.gamedev.net/forums/topic/580957-back-propagation-error/ | # Back Propagation Error
This topic is 2732 days old which is more than the 365 day threshold we allow for new replies. Please post a new topic.
## Recommended Posts
I'm trying to write a generic neural network library and things aren't working out too well. I must be missing something--I understand the concept, but my output is way off. I'm just trying to teach the network XOR.
Here is how I understand the algorithm:
1 Start with an input and the desired output.
2 Each input flows into each neuron in the first layer.
3 For each neuron, solve for e = sum x_i * w_i for i = 1 to num inputs, where w are the connection weights.
4 For each neuron, solve y = s(e), where s is a sigmoid function.
5 Repeat 3 and 4 for each subsequent layer, passing the y values on as the next layer's input
6 Solve for the output error E = desired output - y, where y is the final layer's output
7 For each neuron in the previous layer, solve for error as s'(e) * E
8 Propagate sum error_i * w_i for i = 1 to num current layer's inputs, for each neuron.
9 Repeat 7 and 8 for all previous layers
10 For each layer, update all weights per w_ij += error_i * a * y_j, where a is the learning rate.
OK, that's pretty crappy, hopefully someone's followed along!
It's kind of a lot of code, so I'm only posting the core of it; maybe someone will spot some glaring errors. Any help is appreciated.
First, the train method on the NeuralNetwork class:
void NeuralNetwork::train( vector<TrainingPoint> set, uint iterations ){ //dumbly iterate x times for( int i = 0; i < iterations; i++ ) { cout << "==================================" << endl; //iterate over each input/output pair in the training set for( int j = 0; j < set.size(); j++ ) { int k; //forward step--training input goes into the first layer //previous layer's output goes into each subsequent layer for( k = 0; k < layers.size(); k++ ) { layers[ k ].update( k == 0 ? set[ j ].inputs : layers[ k - 1 ].output ); } vector<double> signal; //calculate output error: e = desired - actual for( k = 0; k < set[ j ].outputs.size(); k++ ) { signal.push_back( set[ j ].outputs[ k ] - layers[ layers.size() - 1 ].output[ k ] ); } //propagate the error back through the network. //each layer calculates all its neuron's errors for( k = layers.size() - 1; k > -1; k-- ) { layers[ k ].propagateError( k == layers.size() - 1 ? signal : layers[ k + 1 ].signal ); } //step back through and update the weights accordingly for( k = 0; k < layers.size(); k++ ) { layers[ k ].updateWeights( k == 0 ? set[ j ].inputs : layers[ k - 1 ].output ); } cout << "target: " << set[ j ].outputs[ 0 ] << " output: " << layers[ layers.size() - 1 ].output[ 0 ] << endl; } } }
Next, the update, propagateError and updateWeights methods on the NeuralLayer class:
//solve for all neuron activations//nn is num neurons, ni is num inputs (equal to previous layer's num neurons)void NeuralLayer::update( const vector<double> input ){ for( int i = 0; i < nn; i++ ) { double x = 0.0f; for( int j = 0; j < ni; j++ ) { x += input[ j ] * weights[ i ][ j ]; } output[ i ] = 1.0f / ( 1.0f + exp( -x ) ); } }//solve for each neuron's error given the following layer's propogated error terms//and produce those same terms for the previous layervoid NeuralLayer::propagateError( const vector<double> propagation ){ int i; for( i = 0; i < nn; i++ ) { error[ i ] = output[ i ] * ( 1.0f - output[ i ] ) * propagation[ i ]; } for( i = 0; i < ni; i++ ) { signal[ i ] = 0.0f; for( int j = 0; j < nn; j++ ) { signal[ i ] += weights[ j ][ i ] * error[ j ]; } } }void NeuralLayer::updateWeights( const vector<double> input ){ for( int i = 0; i < nn; i++ ) { for( int j = 0; j < ni; j++ ) { weights[ i ][ j ] += error[ i ] * rate * input[ j ]; } } }
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worked it out, just a logic problem | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 1, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.5337977409362793, "perplexity": 7976.031513587332}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.3, "absolute_threshold": 20, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2018-09/segments/1518891813626.7/warc/CC-MAIN-20180221143216-20180221163216-00360.warc.gz"} |
http://stats.stackexchange.com/questions/97722/confidence-interval-for-the-intercept-in-logistic-regression | # Confidence interval for the intercept in logistic regression
Some major commercial statistical packages (e.g., SPSS) do not report a CI for the intercept term in logistic regression. [Based on answer below R does provide CI for intercept]
Why might confidence intervals for the intercept term not be included by default?
UPDATE:
Based on feedback, Confidence Intervals for odds associated with intercept term are reported in some stat. packages. And, obviously, they can be easily computed manually, knowing the standard error. Therefore, reformulated question:
What is the interpretation of intercept's CIs (for odds) in logistic regression?
-
Although I can find plenty of annotated outputs of SPSS binary logistic regression on the Web, none of them directly provide confidence intervals, but they all report standard errors (from which CIs are easily computed), including for the constant term. Do you think you could document the behavior you are asking about by means of a reproducible example? – whuber May 14 at 19:01
SPSS is good for behavioral sciences, where they normally don't care about those C.I that much ;) – Stat May 14 at 19:06
I agree with both above comments. But still I found it a bit suspicious - please see my comments to gung's answer below – user2028058 May 14 at 19:07
Use Generalized Linear Model, you'll get 95% CI that way. But I agree with another answer that 95%CI in terms of Odds Ratio for the intercept is pretty hard to interpret. – Penguin_Knight May 14 at 19:24
Is there an option to run the model without the intercept in SPSS? (I know there is for linear regression, not sure about logistic). If so, create a variable in SPSS which is equal to 1 for everyone, put that in as a predictor, and ask to remove the intercept. The new variable will be the intercept and will have CIs. – Jeremy Miles May 14 at 20:09
Well, that's not correct. You can use confint funtion in both S-plus and R to obtain C.I. for the estimated parameters. I will give an example for logistic regression in R since I don't have the S-plus:
> mydata <- read.csv("http://www.ats.ucla.edu/stat/data/binary.csv")
> mylogit <- glm(admit ~ gre + gpa + rank, data = mydata, family = "binomial")
> confint(mylogit)
Waiting for profiling to be done...
2.5 % 97.5 %
(Intercept) -5.7109591680 -1.260314066
gre 0.0001715446 0.004461385
gpa 0.1415710585 1.428341503
rank -0.8149612229 -0.315479733
>
-
Interesting. I haven't checked R.. E.g. SPSS doesn't provide CIs for intercept. Please see updated question – user2028058 May 14 at 18:48
I don't have access to SPSS, but I strongly suspect that it can output a confidence interval for the intercept in logistic regression. You probably have to know how to use the underlying syntax (e.g., PASTE) to call for it.
As to why it isn't output by default, you'd really have to contact the company. But I would guess that they believe people aren't very interested in seeing the CI for the intercept and want to minimize the volume of statistical output.
-
Thanks. I've checked documentation and all UI options and I'm pretty sure that there is no option to display CI for intercepts. They provide a table with coefficients and statistics including CIs for predictors - but leave space for CI for intercept empty. For instance, ats.ucla.edu/stat/spss/output/logistic.htm - last table. – user2028058 May 14 at 19:05
Therefore I became curious - maybe this can be justified by some reasoning (though I don't see any) – user2028058 May 14 at 19:06
I don't know SPSS's syntax, but I believe it can be done the UCLA page notwithstanding. You can also compute it yourself (remember that the SEs will be on the scale of the linear predictor) fairly easily. – gung May 14 at 19:11
At the related page ats.ucla.edu/stat/stata/faq/oratio.htm (about 2/3 the way down) the SPSS output includes a CI for the constant by default. This is because no odds ratio calculations were requested. I'm not surprised that CIs are not provided for an odds ratio for a constant: after all, what would that even mean? Thus it would behoove us all to distinguish carefully between output in terms of the raw parameter estimates and output in terms of odds ratios. – whuber May 14 at 19:23 | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 1, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.6022939085960388, "perplexity": 1741.2504511579357}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2014-49/segments/1416400380574.41/warc/CC-MAIN-20141119123300-00143-ip-10-235-23-156.ec2.internal.warc.gz"} |
https://www.maths.lancs.ac.uk/~choiy1/pubmath/papers/CFO_amenoa.html | ## A nonseparable amenable operator algebra which is not isomorphic to a C*-algebra
#### Authors
Yemon Choi, Ilijas Farah, Narutaka Ozawa*
* Corresponding author
MSC 2010: 47L30 (primary); 03E75 46L05 (secondary)
DOI: 10.1017/fms.2013.6
#### Status
Preprint version available at arXiv 1309.2145
#### Reviews
[ Math Review (summary) | Zentralblatt ]
#### Abstract
It has been a longstanding problem whether every amenable operator algebra is isomorphic to a (necessarily nuclear) C*-algebra. In this note, we give a nonseparable counterexample. The existence of a separable counterexample remains an open problem. We also initiate a general study of unitarizability of representations of amenable groups in C*-algebras and show that our method cannot produce a separable counterexample.
The original preprint of this paper was written by IF and NO, with the original counterexample containing all of $K(H)$ and hence not being contained in a subhomogeneous von Neumann algebra. YC's contributions, among them the observation that the original method could be adapted to get counterexamples inside $\ell^\infty\overline{\otimes}{\bf M}_2$, came in later versions. | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 1, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.9142627716064453, "perplexity": 1564.4293398844845}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2021-39/segments/1631780057447.52/warc/CC-MAIN-20210923195546-20210923225546-00087.warc.gz"} |
http://math.stackexchange.com/questions/174743/show-a-is-real-equivalent-to-its-transpose | # Show $A$ is “real-equivalent” to its transpose
The problem statement:
Let $A$ be a real $9\times 9$ matrix with transpose $B$. Prove that the matrices are real equivalent in the following sense: There exists a real invertible $9\times 9$ matrix $H$ such that $AH=HB$.
Unfortunately, I don't have much of an attempt at a solution. My first thought was to notice that $A$ and $B$ have the same Jordan normal form so they're similar. But the Jordan form may have complex entries as the eigenvalues may be complex. Also confusing is why the matrix is $9\times 9$. How could this matter? Nine is a perfect square and it's odd, but so are a lot of other numbers.
Any help is welcomed.
-
The key is to prove the following:
Theorem. Let $A$ and $B$ be matrices with real coefficients. If $A$ and $B$ are similar over $\mathbb{C}$, then they are similar over $\mathbb{R}$.
This problem appears, among other places, in Berkeley Problems in Mathematics, by de Souza and Nuno Silva (Problem 7.7.10 in the second edition; the problem has been used many times in the Prelim exam at Berkeley). The book offers two answers, though I think that one of the solutions (using the rational canonical form) is a bit sloppy.
Here is the other approach. Assume $A = UBU^{-1}$, with $U$ a complex matrix. Write $U=K+iL$, where $K$ and $L$ are real matrices, and assume that $L\neq 0$. Then $$A(K+iL) = AU = UB = (K+iL)B$$ and so the real parts and imaginary parts of these matrices are equal. That is, $AK = KB$ and $AL = LB$ (the problem is we don't know that $K$, by itself, is invertible).
Now, for any complex number $z$ we have $A(K+zL) = (K+zL)B$. Let $p(z) = \det(K+zL)$. Prove that $p$ is not identically zero, and take a real number that is not a root.
Once you have this theorem, your observation that $A$ and $B$ are similar over $\mathbb{C}$ implies the result you want.
(For what it is worth, the other argument given by the book is that the Rational canonical forms of $A$ and $B$ have to be the same, since they are the same over $\mathbb{C}$, and so $A$ and $B$ are similar over $\mathbb{R}$; the reason this is sloppy is that the rational canonical form is usually defined, for uniqueness purposes, in terms of the irreducible factors of the minimal/characteristic polynomials, and the rational blocks are companion matrices of powers of these irreducible factors. But the irreducible factors over $\mathbb{R}$ are not necessarily the same as the irreducible factors over $\mathbb{C}$, so that the "uniqueness" of the rational canonical form does not directly apply; an argument needs to be made that the equality over $\mathbb{C}$ implies an equality when the irreducible factors are taken over $\mathbb{R}$ instead, and this argument is missing in the book).
-
You don't need to know the degree of $p$. Since $p(i) \ne 0$, $p$ is not identically $0$, so there are real non-roots. – Robert Israel Jul 24 '12 at 19:11
@RobertIsrael: Oh, right. And thanks for correcting the typo. – Arturo Magidin Jul 24 '12 at 19:11
Thanks for the excellent answer. – Derek Allums Jul 24 '12 at 19:20 | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 1, "mathjax_display_tex": 1, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.9727489948272705, "perplexity": 112.23683100021438}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2015-27/segments/1435375096290.39/warc/CC-MAIN-20150627031816-00160-ip-10-179-60-89.ec2.internal.warc.gz"} |
https://hkumath1111.wordpress.com/2014/10/27/lecture-18-2/ | # Linear Algebra II
## October 27, 2014
### Lecture 18
Filed under: 2014 Fall — Y.K. Lau @ 7:00 PM
We introduce the concept of change matrix. (See Lect18.pdf) Next lecture we shall see how it is used to answer the question: what is the relation between ${M_{FE}(T)}$ and ${M_{DB}(T)}$?
Some preparation: In the coming lecture we shall (re-)visit eigenvalues and eigenvectors that you are supposed to know their definitions and the method to find them. To refresh your memory, please read the following.
Given an ${n\times n}$ matrix ${A}$. If ${\lambda\in{\mathbb R}}$ and ${\underline{0}\neq \underline{x}\in {\mathbb R}^n}$ satisfy ${A\underline{x}=\lambda \underline{x}}$, then ${\lambda}$ is called the eigenvalue of ${A}$ and ${\underline{x}}$ is said to be an eigenvector of ${A}$ corresponding to ${\lambda}$. Note that by definition ${\underline{0}}$ is NOT an eigenvector of ${A}$.
Exercise. Let ${\lambda}$ be an eigenvalue of ${A}$. Show that
$\displaystyle E_\lambda(A):=\{\underline{x}\in{\mathbb R}^n: \ A\underline{x}=\lambda \underline{x}\}$
is a subspace of ${{\mathbb R}^n}$. We call ${E_\lambda(A)}$ the eigenspace of ${A}$ corresponding to ${\lambda}$, thus ${E_\lambda(A)}$ is the set of all eigenvectors corresponding to ${\lambda}$ and the zero vector.
Method:
• The eigenvalues of ${A}$ are found by solving the characteristic equation
$\displaystyle \det (xI-A)=0$
which is in fact a polynomial in ${x}$ of degree ${n}$. (${I=}$ the ${n\times n}$ identity matrix.)
• The eigenvectors corresponding to ${\lambda}$ are found by solving the matrix equation in ${\underline{x}}$:
$\displaystyle (\lambda I- A)\underline{x}=\underline{0}$
All nonzero solutions of ${\underline{x}}$ are the eigenvectors for ${\lambda}$.
(See Textbook p.151-153 for examples.)
After Class Exercises: Ex 9.2 Qn 1(b), 4(b), 5(b), 7(b) (See textbook’s solution and L18-ace.pdf)
Revision: Ex 9.1 Qn 16, 22. (See L18-ace.pdf) | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 34, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.9919843077659607, "perplexity": 276.80596806061266}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2017-26/segments/1498128323801.5/warc/CC-MAIN-20170628204133-20170628224133-00147.warc.gz"} |
https://latkin.org/blog/2012/03/20/how-to-calculate-1-million-digits-of-pi/ | # I'VE GOT THE BYTE ON MY SIDE
## How to calculate 1 million digits of pi
Mar 20, 2012
$$\pi$$ day (half $$\tau$$ day? hmmm) rolled around last week, and it got me wondering - how exactly does one go about calculating large numbers of digits for mathematical constants, $$\pi$$ in particular? One hears about how $$\pi$$ , $$e$$ , and the like have been calculated out to millions, billions, or even trillions of digits. I had a vague idea that some series expansion is used in order to build up the value piece by piece. But is each digit calculated individually, or does the entire value need to be stored in memory at once? What kind of data types are needed?
Some simple web searches on the subject will steer you toward the Wikipedia articles on $$\pi$$ and approximations of $$\pi$$ . These give nice examples of the various different series expansions which can be used, as well as some interesting history on the topic. We note that the Baily-Borwein-Plouffe formula or its relatives can be used to calculate (base-16) digits of $$\pi$$ independently (i.e. without needing to calculate any other digits besides the one you want), but that this is somewhat of a special case. There is no general method for doing this for an arbitrary mathematical constant. Until someone comes up with a specialized clever formula, the entire value up to the desired precision typically needs to be calculated together.
What’s missing from the Wikipedia articles are implementation details. Further web searches took me to a few sites with code that was fabulously confusing, or even plain wrong. However this site, last updated in 1997, turned out to be just what I was looking for. The author provides some of the details of how to do the calculation via the quickly-converging formula (found by Machin in 1706)
$$\pi = 4 (4 \tan^{-1}(\frac{1}{5}) - \tan^{-1}(\frac{1}{239}))$$
He gives a great explanation of how to code the Taylor expansion of arctan, and various pitfalls of different computational approaches. However, even this page leaves out some crucial details. He refers to the formula above, as well as the Taylor expansion itself, as “black magic” which should be taken on faith. That’s no good if you ask me. I don’t know how Machin came up with his formula, but it is not too hard to verify that it’s accurate. And many of us were taught Taylor series in high school, so they can’t be all that bad. [Historical bonus facts: Machin was Taylor’s doctoral advisor at Cambridge, and the two served together in the Royal Society, both ending up on the board which adjudicated the Newton/Leibniz dispute.]
The biggest omission, though, is that the author doesn’t reveal how to implement the high-precision number class he’s using in all of his code. He teases us by merely stating that with “careful coding of these routines” we can do the calculation. He also makes frequent reference to C++ being a “high-level” language, which I guess was less amusing of a statement in 1997.
So let’s create our own high-precision number class (in C#) and carry out the calculation. Here are the goals:
1. Use only types that are in standard .NET libraries (.NET 4.0 is most recent release at the time of writing)
• OK I’m cheating a bit here. We will use the unbounded integer class System.Numerics.BigInteger, which is fantastically optimized and will give us a lot for free. Trust me, though, our code would be fast enough even with a super simple BigDecimal implementation (i.e. just keep the decimal digits before and after the decimal point in int arrays, and carry out normal long division, multiplication, etc, like we learned in elementary school). This was actually my first approach, but it requires a lot more code.
2. Have it be fast enough to calculate 1 million digits in “reasonable” time.
Our HighPrecision class will be a limited-precision rational number class, which only keeps track of enough data to maintain some set number of accurate digits after the decimal. How do we do that? Well say we some rational number $$r = \frac{p}{q}$$ and we want to find its decimal representation to $$k$$ digits after the decimal. Then what we really want is some rational number $$r^{\prime} = a/10^k$$ , since any decimal number with a finite number of digits can be expressed as an integer divided by an appropriately large power of 10 (e.g. 0.25 = 25100). To calculate $$a$$ , we simply set $$a/10^k=\frac{p}{q}$$ and come to $$a = p \times 10^k / q$$ . We can let this quotient be truncated like normal with computer integer division, since we are only hoping for an approximation to $$r$$ .
So really, the trick to our limited-precision rational class is to keep a constant denominator equal to $$10^k$$ , and make sure that during any calculation the numerator is appropriately rescaled. Here’s the code:
public class HighPrecision
{
private static BigInteger denom;
private static int precision;
private static int slop = 4;
private BigInteger num;
public HighPrecision(BigInteger numerator, BigInteger denominator)
{
// public constructor rescales numerator as needed
num = (HighPrecision.denom * numerator) / denominator;
}
private HighPrecision(BigInteger numerator)
{
// private constructor for when we already know the scaling
num = numerator;
}
public static int Precision
{
get { return precision; }
set
{
HighPrecision.precision = value;
denom = BigInteger.Pow(10, HighPrecision.precision + slop); // leave some buffer
}
}
public bool IsZero
{
get { return num.IsZero; }
}
public BigInteger Numerator
{
get { return num; }
}
public BigInteger Denominator
{
get { return HighPrecision.denom; }
}
public static HighPrecision operator *(int left, HighPrecision right)
{
// no need to resale when multiplying by an int
return new HighPrecision(right.num * left);
}
public static HighPrecision operator *(HighPrecision left, HighPrecision right)
{
// a/D * b/D = ab/D^2 = (ab/D)/D
return new HighPrecision((left.num * right.num) / HighPrecision.denom);
}
public static HighPrecision operator /(HighPrecision left, int right)
{
// no need to rescale when dividing by an int
return new HighPrecision(left.num / right);
}
public static HighPrecision operator +(HighPrecision left, HighPrecision right)
{
// when we know the denominators are the same, can just add the numerators
return new HighPrecision(left.num + right.num);
}
public static HighPrecision operator -(HighPrecision left, HighPrecision right)
{
// when we know the denominators are the same, can just subtract the numerators
return new HighPrecision(left.num - right.num);
}
public override string ToString()
{
StringBuilder sb = new StringBuilder();
// pull out the integer part
BigInteger remain;
BigInteger quotient = BigInteger.DivRem(num, HighPrecision.denom, out remain);
int integerDigits = quotient.IsZero ? 1 : (int)BigInteger.Log10(quotient) + 1;
sb.Append(quotient.ToString());
int i = 0;
BigInteger smallDenom = HighPrecision.denom/10;
BigInteger tempRemain;
// pull out all of the 0s after the decimal point
while (i++ < HighPrecision.Precision && (quotient = BigInteger.DivRem(remain, smallDenom, out tempRemain)).IsZero)
{
smallDenom /= 10;
remain = tempRemain;
sb.Append('0');
}
// append the rest of the remainder
sb.Append(remain.ToString());
// truncate and insert the decimal point
return sb.ToString().Remove(integerDigits + HighPrecision.Precision).Insert(integerDigits, ".");
}
}
By far the most complicated part is the ToString() method, the rest is basic fraction operations with a shortcut or two thrown in. Once we have the high precision number class, it is only a matter of plugging it in to the code for arctan:
public static HighPrecision GetPi(int digits)
{
HighPrecision.Precision = digits;
HighPrecision first = 4 * Atan(5);
HighPrecision second = Atan(239);
return 4 * (first - second);
}
public static HighPrecision Atan(int denominator)
{
HighPrecision result = new HighPrecision(1, denominator);
int xSquared = denominator * denominator;
int divisor = 1;
HighPrecision term = result;
while (!term.IsZero)
{
divisor += 2;
term /= xSquared;
result -= term / divisor;
divisor += 2;
term /= xSquared;
result += term / divisor;
}
return result;
}
Using this code, my laptop (2.5 GHz Intel Core i5) can churn out $$\pi$$ to 1 million digits after the decimal point in a bit under 53 minutes. Producing the string representation takes another minute and forty seconds. Using a fully homegrown solution (no BigInteger) with no attempt at optimization resulted in a runtime of about 8 hours, which is still in the realm of “reasonable” if you ask me.
The exercise I leave to the reader is to parallelize the above code for Atan. After parallelizing with TPL, runtime on my work desktop (4 core, 2.8 GHz Intel Core i7) came down to about 17 minutes for 1 million digits.
Having done the calculation myself, I feel I have now earned the right to spend a lot of money on invest in this poster. Or perhaps I will print my own.
Finally, I want to mention that this is still a very basic/nonoptimized approach compared to what leading researchers are doing. Search around or check out this link for more gory details on how the pros do it. | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 2, "mathjax_asciimath": 1, "img_math": 0, "codecogs_latex": 18, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.4411408305168152, "perplexity": 2339.764517766845}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2019-43/segments/1570986684226.55/warc/CC-MAIN-20191018154409-20191018181909-00510.warc.gz"} |
https://imathworks.com/tex/tex-latex-tex-root-to-parent-directory/ | # [Tex/LaTex] %!TEX root = to parent directory
compilingpaths
Currently, I am writing a large report. In my previous ones, I always had the chapters and the main file (thesis.tex) in the same directory as the individual chapters. This time, however, I created a subfolder called "chapters" and put the chapter .tex files in there. But obviously, the command
%!TEX root = thesis.tex"
which I previously put at the beginning of each chapter.tex, does not work anymore. Since I work on the report from different locations, I can not define an absolute path but need to define a relative one. I tried %!TEX root = ../thesis.tex and /%!TEX root = thesis.tex, both of which do not work.
I found threads and solutions for \input and other commands, none of which solve by problem, though. If anyone was able to shed some light here, I'd be very thankful!
Try %!TEX root = ../thesis.tex` | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 1, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.9748020768165588, "perplexity": 1663.3459717465048}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2022-40/segments/1664030337855.83/warc/CC-MAIN-20221006191305-20221006221305-00724.warc.gz"} |
https://collegephysicsanswers.com/openstax-solutions/slap-shot-hockey-player-accelerates-puck-velocity-800-ms-400-ms-same-direction | Question
In a slap shot, a hockey player accelerates the puck from a velocity of 8.00 m/s to 40.0 m/s in the same direction. If thisshot takes $3.33 \times 10^{-2} \textrm{ s}$, calculate the distance over which the puck accelerates.
$0.799 \textrm{ m}$
Solution Video | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 1, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.9001057744026184, "perplexity": 1760.602919331477}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2020-10/segments/1581875145839.51/warc/CC-MAIN-20200223185153-20200223215153-00148.warc.gz"} |
https://math.stackexchange.com/questions/2022463/solving-4-q-q2-14qq2 | Solving $4-q-q^2 = 1+4q+q^2$
Given a market demand function:
$$p=4-q-q^2$$
and the market supply function:
$$p=1+4q+q^2$$
We can solve for:
$$4-q-q^2 = 1+4q+q^2$$
When I move the terms from right to left, I get $3-5q-2q^2$, but from left to right $2q^2+5q-3$.
I understand multiplying by $-1$ will give me the inverse of the other.
To determine the equilibrium price and quantity, we can use the quadratic formula:
$$x=\frac{-b\pm\sqrt{b^2-4ac}}{2a}$$
However, this will give a different result depending on which direction I have collected the terms.
My question is therefore, how do I know which of the two I use to solve the problem?
• What is your question? – user259242 Nov 20 '16 at 11:20
• "Obviously, this gives a different result depending on the direction": sorry but there is nothing obviously different. Solve these two equations to see. – Yves Daoust Nov 20 '16 at 11:28
• Sorry, have clarified my question a little. – Dan Nov 20 '16 at 11:38
• Note that by definition $a$ is the coefficient of the $q^2$ term, $b$ the coefficient of the $q^1$ term and c the coefficient of the $q^0$, aka the constant term. – Hyperplane Nov 20 '16 at 12:09
• Okay, taking the q^2 term we still have 2q^2 and -2q^2, so how would I know which one was correct? – Dan Nov 20 '16 at 12:14
When you move arguments from right to left you get:
$3 - 5q - 2q^2 = 0$
and you can multiply this expression by (-1) and keep the equivalency, so you get:
$2q^2 + 5q - 3 = 0$
When you solve these for x, you will get the same solutions.
Edit: the solutions for x of both equations are 1/2 and -3, you must have missed something while putting the numbers in the formula. (put both these numbers instead of x, you should get an equality.) I can only assume you missed a minus somewhere, because the +/- operator sometimes confuses people.
• I've update my question a little. Could you shed some light? – Dan Nov 20 '16 at 11:59
• I've edited my answer, it should be okay now. :) – Collapse Nov 20 '16 at 14:08 | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 1, "mathjax_display_tex": 1, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.812255322933197, "perplexity": 280.37815305954757}, "config": {"markdown_headings": false, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2019-43/segments/1570987763641.74/warc/CC-MAIN-20191021070341-20191021093841-00158.warc.gz"} |
https://tex.stackexchange.com/questions/204974/how-to-change-the-appearance-of-listof-headers | # How to change the appearance of listof headers?
I'm an amateur user of LaTeX and I'm writing my PhD thesis using a template that I found in: PhDtemplateLATEX
Looking inside Classes/CUEDthesisPSnPDF.cls, I found that it uses fancyhdr for the customization of headers and footers. Specifically:
\pagestyle{fancy}
\renewcommand{\chaptermark}[1]{\markboth{\MakeUppercase{\thechapter. #1 }}{}}
\renewcommand{\sectionmark}[1]{\markright{\thesection\ #1}}
\fancyhf{}
\fancyfoot[C]{\thepage}
\renewcommand{\footrulewidth}{0pt}
\fancypagestyle{plain}{
}
I have changed it, because I wanted the headers and footers with "small caps" style and "scriptsize" size.
The problem appears in the header of the frontmatter (the footer is ok), I mean: the table of contents, the list of figures and the list of tables. In this case, the header appears with bolded capitals, and I would want the same format of the rest of the document.
I've tried to change it introducing the "markboth" command in the following way:
\frontmatter
\setcounter{secnumdepth}{3} % organisational level that receives a numbers
\markboth{\sc {\scriptsize \contentsname}}{\sc {\scriptsize \contentsname}}
\listoffigures % print list of figures
\markboth{\sc {\scriptsize \listfigurename}}{\sc {\scriptsize \listfigurename}}
\listoftables % print list of tables
\markboth{\sc {\scriptsize \listtablename}}{\sc {\scriptsize \listtablename}}
... and it works, if the list has two pages. If the list has more than two pages, the last two pages have the desired format, but the rest of pages have the original format. For example, if the table of contents has six pages, the first page has no header (that's ok), pages 2-4 have the original format, and pages 5-6 have the desired format. This occurs with the table of contents and the list of figures (with the list of tables I haven't problems yet, because, for now, it has only two pages).
So... what can I do?
I will appreciate any help. Thanks.
--------------------------------------EDIT----------------------------------------
Ok, I've tried the suggestion of @Johannes_B and my document has improved, but the problem is not completely solved.
Specifically, I've modified (using package etoolbox):
\frontmatter
\patchcmd{\tableofcontents}{%
{\MakeUppercase\contentsname}{\MakeUppercase\contentsname}%
}{
{\scriptsize {\sc \contentsname}}{\scriptsize {\sc \contentsname}}%
}
{}{}
\patchcmd{\listoffigures}{%
{\MakeUppercase\listfigurename}{\MakeUppercase\listfigurename}%
}{
{\scriptsize {\sc \listfigurename}}{\scriptsize {\sc \listfigurename}}%
}
{}{}
\patchcmd{\listoftables}{%
{\MakeUppercase\listtablename}{\MakeUppercase\listtablename}%
}{
{\scriptsize {\sc \listtablename}}{\scriptsize {\sc \listtablename}}%
}
{}{}
\setcounter{secnumdepth}{3} % organisational level that receives a numbers
\tableofcontents
\listoffigures
\listoftables
In the case of the table of contents, the header appears exactly as I want it: In scriptsize and small caps, so this is a great improvement. But, in the case of the list of figures and the list of tables, I have no changes: The headers are still in normal size and bolded capitals.
Any suggestions? Thanks.
• Welcome to TeX.SX! Please help us to help you and add a minimal working example (MWE) that illustrates your problem. It will be much easier for us to reproduce your situation and find out what the issue is when we see compilable code, starting with \documentclass{...} and ending with \end{document}.
– user31729
Oct 7 '14 at 13:20
• Possibly related: \addtocontents at end of document not getting written to .toc file? -- that was when I was trying to get various page styles attached to front matter lists. Oct 7 '14 at 13:23
• Christian, I don't know how to do what you are asking for, sorry. I mean, I don't know how to gather all the information distributed in the main file.tex and the class file. But, in the link of the template, there is a compilable example (with chapters and so on), that could be helpful. Oct 7 '14 at 14:06
• Mike, I will read carefully your link, but I need some time to understand it. Thank you anyway. Oct 7 '14 at 14:09
• Does this help? tex.stackexchange.com/questions/185310/… Oct 7 '14 at 15:49
After a bit of Sherlock Holmes deduction power the whole thing comes down a a very basic example and a very straight forward solution. The template file uses package tocbibind to print the \listofs and bibliography to the table of contents. tocbibind provides a hook that we can redefine without patching any stuff.
I defined a new macro to define the appearance called \listheaderfont. It is red now just to demonstrate. This has a huge advantage, all instances use this macro, so changing this changes the document in a more consistent way.
\documentclass{book}
\usepackage{tocbibind}
\usepackage{xcolor}
%defining the apperance of the listheaders
\renewcommand{\tocetcmark}[1]{
\usepackage{pgffor}
\begin{document}
\tableofcontents
\listoffigures
\listoftables
\begin{table}\foreach \n in {1,...,70} {\caption{}}
\end{table}
\begin{figure}\foreach \n in {1,...,70} {\caption{}}
\end{figure}
\nocite{aristotle:physics}
\bibliographystyle{plain}
\bibliography{biblatex-examples}
\end{document}
We can do this for the standard classes as well, again using a helper macro. This time, no handy package provides a hook we can use. We have to patch the stuff by hand.
\documentclass{book}
%defining the apperance of the listheaders
\usepackage{etoolbox}
\usepackage{xcolor}
\patchcmd{\tableofcontents}{%
{\MakeUppercase\contentsname}{\MakeUppercase\contentsname}%
}{
}
{}{}
\patchcmd{\listoffigures}{%
{\MakeUppercase\listfigurename}{\MakeUppercase\listfigurename}%
}{
}
{}{}
\patchcmd{\listoftables}{%
{\MakeUppercase\listtablename}{\MakeUppercase\listtablename}%
}{
}
{}{}
\usepackage{pgffor}
\begin{document}
\tableofcontents
\listoffigures
\listoftables
\begin{table}\foreach \n in {1,...,70} {\caption{}}
\end{table}
\begin{figure}\foreach \n in {1,...,70} {\caption{}}
\end{figure}
\end{document}
• I'm so sorry, but I'm stupid. The class I provided is not exactly the same class I'm using, but a modified version (I haven't realized till now). The class that I'm actually using is: <openwetware.org/wiki/LaTeX_template_for_PhD_thesis. If I use your MWE with Classes/CUEDthesisPSnPDF.cls it works, but If I use your MWE with Latex/Classes/PhDthesisPSnPDF.cls (the class that I'm using) it doesn't work: the header of table of contents is ok, but the header of list of figures and tables are in normal size and bolded capitals. Sorry again and thanks for your patience. Nov 4 '14 at 11:29
• I've modified the information of the question with the real template. Nov 4 '14 at 11:35
• Please compile the first example as it is, is the header of the toc red as well? The template uses the option notoc to not print the toc to the toc (which is a good idea) and hence doens't take control over it. I didn't test this case, sorry. I think, the package should take over. Nov 5 '14 at 15:51
A simple solution not involving any additional packages is the following: Simply redefine \contentsname or \listtablename so that it contains a \lowercase command.
\renewcommand\contentsname{C\lowercase{ontents}} | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 1, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.6006935834884644, "perplexity": 1640.9060986748343}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2022-05/segments/1642320302706.62/warc/CC-MAIN-20220120220649-20220121010649-00116.warc.gz"} |
https://www.beckman.mx/resources/technologies/laser-diffraction/measuring-small-particles | # Measuring Small Particles
Smaller particles pose a real challenge for laser diffraction technology. When illuminated by a laser beam, large particles scatter light at low angles with easily detectable maxima and minima in the scattering pattern. Detectors placed at low angles relative to the optical path with sufficient angular resolution can detect these maxima and minima. As particles become smaller, the ratio of particle dimension to light wavelength (d/λ) is reduced, resulting in a smoother and less angular scattering pattern making measurement difficult. In addition, small particles scatter light weakly and maxima and minima can be measured only at very high angles, which affects detection and resolution of the scattering pattern. Different manufacturers use different solutions to address these limitations with varying degrees of success. Most focus on the measurement of back-scattered light.
## Bias in Sizing of Non-spherical Particles
Most laser-based particle sizing devices make no allowance for the shape of materials being tested, regardless of particle size. Mathematical models used to calculate distributions are based on spherical systems, so any reported distribution is essentially equivalent to a spherical distribution of the material being analyzed. In most cases this is sufficient as many particles emulate a spherical system closely enough. But for many particles that deviate from perfect sphericity, the size distribution obtained is only apparent or nominal and will be biased. In some extreme cases results using a spherical model on non-spherical particles will be very different from reality. This bias emerges when comparing laser diffraction results with others, such as polarization intensity differential scattering or PIDS.
## PIDS vs. Laser Diffraction
PIDS technology is based on the Mie theory of light scattering and relies on the transverse nature of light. With a magnetic and electric vector (at 90°), if the electric vector is up-and-down the light is considered to be vertically polarized. When a sample is illuminated with light of a given polarized wavelength, the oscillating electrical field creates a dipole (or oscillation) of the electronics in the sample. These oscillations are in the same polarization plane as the propagated light source, and oscillating particle dipoles will radiate light in all directions except that of the irradiating light source. Three wavelengths (450 nm, 600 nm and 900 nm) successively illuminate the sample with vertically and then horizontally polarized light. Scattered or radiated light from the samples is measured over a range of angles. By analyzing the differences for each wavelength, we gain information about the particle size distribution of the sample. What’s being measured is the difference between vertically and horizontally polarized signals, not only the values at a given polarization.
## Documentation
• Filter by:
Title Description
WATCH: PIDS TECHNOLOGY VIDEO
Manténganme informado sobre seminarios web, productos, artículos y servicios de Beckman Coulter, incluidos los productos, artículos o servicios de nuestras empresas afiliadas.
Al enviar este formulario, confirmo que he revisado y acepto la Política de privacidad y los Términos de uso. Asimismo, comprendo mis opciones de privacidad ya que pertenecen a mis datos personales, según lo previsto en la Política de privacidad, sección “Sus opciones de privacidad”. | {"extraction_info": {"found_math": false, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.8043771386146545, "perplexity": 2454.7449809434993}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2019-39/segments/1568514574377.11/warc/CC-MAIN-20190921084226-20190921110226-00074.warc.gz"} |
https://www.physicsforums.com/threads/calculate-turning-angle-2-wheels-car.814988/ | # Calculate turning angle - 2 wheels car
1. May 21, 2015
### alona1
i am looking for a function for calculating the turning angle, using the difference between two wheels speed.
i have a model car , with 2 engines and 2 wheels, without steering.
thanks.
2. May 21, 2015
### Baluncore
Welcome to PF.
What do you mean by turning angle? Maybe the radius r, of the curve measured from the midpoint of the car to the centre of the arc would be a better measure. If the car has a width w, with half width being h=w/2, then the radii of the two wheel tracks about the centre of the turn will be r–h and r+h. The relative speeds of the two wheels, u and v, will be proportional to the ratio of the radii.
u/v = (r-h) / (r+h) which I think will give you something like r = h * (u+v) / (u-v)
The sign of r should give you the direction of the turn.
3. May 21, 2015
### alona1
Thanks.
I can't measure the radius r while the car is driving. I know the width W between both wheels and can control the velocities of the wheels.
Is there opportunity to know the angle of the curve by these? For example, for turning 30 degrees what velocities will be needed in each wheel?
4. May 21, 2015
### Baluncore
You do not need to measure the radius. You specify the radius you require, then compute the ratio of the wheel speeds needed to achieve that radius.
If you know the radius you can work out the distance you must travel to change direction by say 30°. Circumference = 2 Pi r,
therefore the distance needed to turn 30° is d = 2 π r * 30 / 360.
5. May 21, 2015
### stedwards
Are you programming a boe-bot?
6. May 22, 2015
### Baluncore
How do you measure or control the wheel position or rates. Shaft encoders, stepper motors?
Similar Discussions: Calculate turning angle - 2 wheels car | {"extraction_info": {"found_math": false, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.8989425897598267, "perplexity": 1155.1632795230025}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2017-47/segments/1510934807089.35/warc/CC-MAIN-20171124051000-20171124071000-00246.warc.gz"} |
https://learnbayes.wordpress.com/2009/10/19/learning-about-an-exponential-rate-and-location/ | Home > MCMC > Learning about an exponential rate and location
## Learning about an exponential rate and location
To illustrate MCMC fitting for a two parameter problem, suppose one observes a sample $y_1, ..., y_n$ from a gamma density with location $\mu$ and rate $\beta$:
$f(y) = \beta exp(-\beta(y - \mu)), y \ge \mu .$
If we assume a uniform prior on $(\mu, \beta)$, then the posterior density is given by
$g(\mu, \beta | y) \propto \prod f(y_i)$,
where $-\infty < \mu < \min y_i, \beta > 0$.
Suppose we observe the following data:
[1] 5.1 5.3 7.1 6.5 3.2 5.2 6.4 9.2 11.4 3.1 3.0 9.4 3.6 5.7 5.0
[16] 3.6 3.1 11.5 3.5 5.5
5.1 5.3 7.1 6.5 3.2 5.2 6.4 9.2 11.4 3.1 3.0 9.4 3.6 5.7 5.0
3.6 3.1 11.5 3.5 5.5
1. First we write a function logpost that computes the log posterior of $(\mu, \beta)$. Since $\beta > 0$, we have to be careful when negative values are input for $\beta$. In the ifelse function, we assign a very large negative value when $\beta < 0$.
logpost=function(theta,y)
ifelse(theta[2]>0,sum(dexp(y-theta[1],theta[2],log=TRUE)),-9e200)
2. Using the mycontour function in the LearnBayes package, we construct a contour plot of the posterior — we add the line $\mu = \min y$ to show the boundary for $\mu$.
mycontour(logpost,c(1.5,3.5,.1,.8),y,xlab=”MU”,ylab=”BETA”,col=”red”)
abline(v=min(y))
3. We’ll try using a random walk Metropolis algorithm where a candidate value is found by
$(\mu, \beta)^c = (\mu, \beta)^i + scale \times Z$,
where $Z$ is normal with mean 0 and variance-covariance matrix $V$. Here it is not quite obvious how to choose $scale$ and $V$ — a normal approximation won’t work here. Looking at the graph, it seems that most of the probability for $\mu$ is in (2, 3) and most of the probability for $\beta$ is in (0.1, 0.6). If we use the rough rule of thumb “4 sd = range of data”, I get estimates for the two standard deviations and these can be squared to get estimates at the variances. I obtain the estimate $V$ = diag(.06, .015). After some trial and error, it seems that the value scale = 1 works ok — the acceptance rate is 25%.
Here are the arguments for the function rwmetrop — I show the simulated draws on top of the scatterplot. It looks like a reasonable sample from the posterior.
fit=rwmetrop(logpost,list(var=diag(c(.06,.015)),scale=1),c(2,.3),10000,y) | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 21, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.9024726748466492, "perplexity": 1809.9937384084935}, "config": {"markdown_headings": true, "markdown_code": false, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2018-05/segments/1516084887832.51/warc/CC-MAIN-20180119065719-20180119085719-00658.warc.gz"} |
http://elib.mi.sanu.ac.rs/pages/browse_issue.php?db=mv&rbr=178 | eLibrary of Mathematical Instituteof the Serbian Academy of Sciences and Arts
> Home / All Journals / Journal /
Matematički VesnikPublisher: Društvo matematičara Srbije, BeogradISSN: 0025-5165 (Print), 2406-0682 (Online)Issue: 68_2Date: 2016Journal Homepage
Decompositions of normality and interrelation among its variants 77 - 86 A. K. Das and Pratibha Bhat
AbstractKeywords: $\kappa$-normal; $\theta$-normal; f$\theta$-normal; w$\theta$-normal; wf$\theta$-normal; $\Delta$-normal; w$\Delta$-normal; wf$\Delta$-normal; $\alpha$-normal; $\beta$-normal; $\pi$-normal; $\Delta$-regularMSC: 54D15
Coefficient inequality for certain subclass of $p$-valent analytic functions whose reciprocal derivative has a positive real part 87 - 92 D. Vamshee Krishna, B. Venkateswarlu and T. RamReddy
AbstractKeywords: $p$-valent analytic function; function whose derivative has a positive real part; second Hankel determinant; positive real function; Toeplitz determinantsMSC: 30C45 30C50
On $\mathcal{I_{\tau}^{\mathcal{K}}}$-convergence of nets in locally solid Riesz spaces 93 - 99 Pratulananda Das and Ekrem Savaş
AbstractKeywords: Ideal; filter; nets; $\mathcal{I_{\tau}}$-convergence; $\mathcal{I_{\tau}^{\mathcal{K}}}$-convergence; $\mathcal{I_{\tau}^{\mathcal{K}}}$-boundedness; $\mathcal{I}_{\tau}^{\mathcal{K}}$-Cauchy; locally solid Riesz spaceMSC: 40G15 40A35
Coarse topologies on the real line 100 - 118 Gerald Kuba
AbstractKeywords: nonmetrizable Baire spaces; metrizable spaces of first categoryMSC: 54A10
Radical transversal screen semi-slant lightlike submanifolds of indefinite Kaehler manifolds 119 - 129 S. S. Shukla and Akhilesh Yadav
AbstractKeywords: Semi-Riemannian manifold; degenerate metric; radical distribution; screen distribution; screen transversal vector bundle; lightlike transversal vector bundle; Gauss and Weingarten formulaeMSC: 53C15 53C40; 53C50
Semi parametric estimation of extremal index for ARMAX process with infinite variance 130 - 139 Hakim Ouadjed and Mami Tawfiq Fawzi
AbstractKeywords: extreme value theory; max autoregressive processes; tail index estimationMSC: 60G70 62G32
Common fixed points in $b$-metric spaces endowed with a graph 140 - 154 Sushanta Kumar Mohanta
AbstractKeywords: $b$-metric; reflexive digraph; point of coincidence; common fixed pointMSC: 47H10 54H25
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https://www.physicsforums.com/threads/rings-and-involution.227480/ | # *-rings and involution
1. Apr 8, 2008
### Mechmathian
First if R is a ring and * is an involution, then U(R, *):= {x \in R|x* · x = 1}
(an involution * is an antihomomorphism such that a** = a for any a)
Now the problem. Find two rings (R, S) with involutions (*, ^) such that U(R, *) is homomorphic to (S, ^). and R and S are not homomorphic.
My first problem is that i do not know of any involutions except for conjugation and transposition for matrixes.
2. Apr 8, 2008
### morphism
I'm assuming you want to find an example where U(R,*) and U(S,^) are isomorphic (as groups), while R and S aren't isomorphic (as rings). Correct?
Maybe this example of a *-ring will help you: The ring of polynomials with complex coefficients $\mathbb{C}[z]$ (viewed as functions on $\mathbb{C}$), with $p(z)^* = \overline{p(\bar{z})}$, where the bar denotes complex conjugation. What's the unitary group of ($\mathbb{C}[z]$,*)?
Last edited: Apr 9, 2008
3. Apr 9, 2008
### Mechmathian
Thank you for another example. The unitary group would be all the complex numbers a: |a|= 1.
I have also thought of Examples with the unitary groups isomprphis to Z\2 and Z\4, but didn't help to solve he problem...
You are correct on the remark, the first isomorphism is an isomorphism of miltiplicative groups.
4. Apr 9, 2008
### Mechmathian
Actually, now that I think about it: an example would be complex numbers (with conjugation = *) and polynomials. Their unitary groups are the same while they are not homomorphic as rings!! I hope I'm right!! Thanks again for the example!
5. Apr 9, 2008
### Mechmathian
By the way the unitary group is +1 and -1 (not what i have said before, because it is true iff there was only one conjugation over the argument)and it is also isomorphic to Z2.. I guess that is another example along with matrices 2*2 (with elements = 0, 1) with * = transposition.
6. Apr 9, 2008
### morphism
Why isn't U(C[z],*) identifiable with the set of complex numbers with absolute value 1 (i.e. the unit circle)? I actually agree with what you said in post #4; that's the example I had in mind.
7. Apr 10, 2008
### Mechmathian
yeah, what i said later isn't true, sorry | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 1, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.9583262801170349, "perplexity": 1746.7666677725897}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2018-39/segments/1537267156780.2/warc/CC-MAIN-20180921033529-20180921053929-00039.warc.gz"} |
https://arxiv.org/abs/1304.4948 | cs.DS
(what is this?)
Title: On the Approximation of Submodular Functions
Abstract: Submodular functions are a fundamental object of study in combinatorial optimization, economics, machine learning, etc. and exhibit a rich combinatorial structure. Many subclasses of submodular functions have also been well studied and these subclasses widely vary in their complexity. Our motivation is to understand the relative complexity of these classes of functions. Towards this, we consider the question of how well can one class of submodular functions be approximated by another (simpler) class of submodular functions. Such approximations naturally allow algorithms designed for the simpler class to be applied to the bigger class of functions. We prove both upper and lower bounds on such approximations.
Our main results are:
1. General submodular functions can be approximated by cut functions of directed graphs to a factor of $n^2/4$, which is tight.
2. General symmetric submodular functions$^{1}$ can be approximated by cut functions of undirected graphs to a factor of $n-1$, which is tight up to a constant.
3. Budgeted additive functions can be approximated by coverage functions to a factor of $e/(e-1)$, which is tight.
Here $n$ is the size of the ground set on which the submodular function is defined.
We also observe that prior works imply that monotone submodular functions can be approximated by coverage functions with a factor between $O(\sqrt{n} \log n)$ and $\Omega(n^{1/3} /\log^2 n)$.
Subjects: Data Structures and Algorithms (cs.DS) Cite as: arXiv:1304.4948 [cs.DS] (or arXiv:1304.4948v1 [cs.DS] for this version)
Submission history
From: Ankit Sharma [view email]
[v1] Wed, 17 Apr 2013 20:02:32 GMT (37kb) | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 1, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.8076856732368469, "perplexity": 621.5248908820173}, "config": {"markdown_headings": false, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 20, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2017-51/segments/1512948514113.3/warc/CC-MAIN-20171211222541-20171212002541-00735.warc.gz"} |
https://biomedicalengineering.international/biomedical-and-environmental-application-of-biosurfactant-produced-by-bacterial-strain-klebsiella-sp-kod36/ | # Biomedical and environmental application of biosurfactant produced by bacterial strain Klebsiella sp. KOD36
https://doi.org/10.33263/BioMed22.058065
Rabail Zulekha 1, Zulfiqar Ahmad 2,*, Azhar Hussain 3, Aslam Farooqi 4, Shaista Andleeb 5
1 Institute of Soil & Environmental Sciences, University of Agriculture, Faisalabad 3804, Pakistan; rabail.zulekha002@gmail.com
2 Key Laboratory for Algal Biology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, China;
3 Department of Soil Science, University College of Agriculture & Environmental Sciences, The Islamia University of Bahawalpur, 63100-Pakistan; azharhaseen@gmail.com
4 Department of Entomology, UCA & ES, The Islamia University of Bahawalpur, Bahawalpur, 63100, Pakistan; aslam_farooqi1770@yahoo.com
5 School of Resources and Environmental Engineering, Wuhan University of Technology, Wuhan, Hubei, 4300723, China; shaistaandleeb444@gmail.com
* Correspondence: zulfiqar@ihb.ac.cn; Scopus ID: 57212260891
## Abstract
Soil microorganisms, particularly bacteria exhibit a lot of potential to produce biosurfactants which are helpful in biomedical and environmental applications. Biosurfactants produced by bacterial strain Klebsiella sp. KOD36 exhibited excellent functional properties, such as biofilm inhibition, cytotoxicity, and in facilitating role in bioremediation of phenanthrene (PHE) in soil matrix and soil-water system. The results of the present study illustrate that partially purified biosurfactant exhibited good hemolytic activity (83%), thrombolytic activity (50%), and biofilm inhibition activity (28%). Additionally, application of biosurfactant along with nutrients NPK (i.e., nitrogen, phosphorus and potassium) enhanced the PHE mineralization potential by Klebsiella sp. KOD36 in all the three different textured soils and soil water systems. These findings reflect the importance of produced biosurfactant in biomedical and environmental field applications.
## 1. Introduction
Biosurfactants have attracted attention as agents of hydrocarbon dissolution since 1960. Biosurfactants have unique structures and a large range of characteristics that can exploited at commercial scales [1]. Biosurfactants are present everywhere in nature and are capable to be utilized in various fields, including biomedicine and therapeutics. Some of the bacteria and yeast release ionic surfactants which are helpful in emulsification of hydrocarbon substrate in growth media. Other microbes alter the structure of their cell wall which can be achieved by synthesis of lipopolysaccharides or non-ionic surfactants within the microbial outer layer [2].
Distinctive advantageous properties for biosurfactants include enhancement of solubility, reduction of surface tension, and little critical micelle concentrations (CMC). The range of CMC of biosurfactants is from 1 to 200 mg/L [3]. Micelle formation plays an important role in microemulsion creation [4], which are clear and stable liquid mixtures of water and oil domains divided by a single layer or aggregates of biosurfactants. When one liquid phase is dispersed in drops in another liquid phase, microemulsions are formed. If oil is dispersed in water, it is termed as direct microemulsion; when water is dispersed in oil, it is termed as reversed microemulsion [5]. High molecular weight biosurfactants are mostly polyanionic heteropolysaccharides consisting of polysaccharides and protein, while low molecular weight biosurfactants are generally glycolipids [6]. As biosurfactants have diverse structures, that make them suitable for biomedical and environmental applications [7, 8]. Since they are environmentally friendly, hence are alternative to synthetic chemical surfactants used in biomedical field as antimicrobial and therapeutic agents. Currently, there is increasing trend in investigating biosurfactants effects on human and animal cells [9]. Biosurfactants produced by Bacillus sp. (lipopeptides), and mannosylerythritol lipids produced by Candida antartica, and rhamnolipids produced by Pseudomonas aeruginosa, exhibited excellent properties as antimicrobial agents [10].
The main objective of the study was to evaluate the biological activities and functional properties of biosurfactants produced by Klebsiella sp. KOD36 and their application in the biomedical and environmental fields.
## 2. Materials and Methods
2.1. Culture medium, chemicals, and microorganism
The strain already isolated and identified as Klebsiella sp. through 16s RNA (accession number KT364873) was used in present study [11]. Mineral salts (MSM), NaCl (1.0 g/l), CaCl2 (0.1 g/l), KH2PO4 (1.0 g/l), MgSO4∙7H2O (0.5 g/l), Na2HPO4 (1.0 g/l), and yeast extract (4.0 g/l) were used for the purification and streaking of bacterial strains already reported to produce biosurfactants. All solutions have been prepared in distilled water at 121°C for 20 minutes.
2.2. Cytotoxicity test (hemolytic activity)
Human blood (3 mL) was mixed thoroughly with purified sample of biosurfactant and then poured into a 15 mL screw capped tube to centrifuge for 5 min according to the method of Tabasum et al. [12]. The supernatant was collected after centrifugation and the viscous pellets obtained were subjected to washing thrice with phosphate buffer saline (PBS) (5 mL) solution. The cells (after washing) were then suspended in sterile PBS (final volume 20 mL), and later counted on hemocytometer. Ice was used to maintain the blood cell suspension and diluted with sterile PBS. Peptide aliquots (20 mL) were placed into 20 mL microfuge tubes. Diluted blood cell aliquots (180 mL), the suspension collected were placed in each two milliliter tube aseptically and mixed smoothly thrice with pipette tip. Tubes were incubated at 37°C with agitation for 35 min. Immediately the tubes were placed for 5 min on ice and centrifuged for five minutes. 100 ml aliquots of supernatant were collected carefully and placed into 1.5 ml centrifuge tube. It was further diluted with 900 ml chilled sterile PBS. After dilution, all centrifuged tubes were placed on wet ice. Three replicates were run for each. Absorbance was measured at 576 nm.
2.3. Thrombolytic activity
Twenty healthy volunteers were selected, and their venous blood was transferred to a pre-weighed sterile microcentrifuge tube (500 µL/tube) and incubated at 37°C for 45 minutes. When the clot formation occurred, the serum was removed completely (care was taken while aspiration to avoid disturbance of clot formation) and then weight of each tube was measured to determine the weight of clot (which was equal to the difference between the clot weight) containing tube and the weight of the tube alone). Each clot-containing microcentrifuge tube was labeled and 100 µL of crude extract and its polar fractions collected were then added to respective tube. For a negative thrombolytic control, water was added to one of the tube (having clot formation). For clot formation, this experimental set up were then placed in temperature (at 37°C) controlled incubator for 90 minutes. After incubation, the fluid formed were removed and each tube were gain weighed to calculate the difference in weight after the clot disruption. The % of clot lysis were measured as difference in weight before and after the clot lysis.
2.4. Biofilm inhibition activity
The inhibition in bacterial biofilm formation (Bacillus subtilis) was calculated by adopting microtiter-plate method previously described by Stepanovic et al. [13]. The wells of 24-well sterile tissue culture plate were then filled with nutrient broth of volume 100 microliter (Oxoid, UK). The testing sample with concentrations of 2.5 µg was dissolved in one milliliter of DMSO, and the added in different wells. Uniform bacterial culture each with 1×109 cell density was inoculated. The treatment as positive control having Rifampicin and nutrient broth and negative control having only the bacterial culture and nutrient broth was set. The plates were covered and incubated in temperature controlled incubator (370C) for 24 hours. Later the wells were beheaded and washed thrice with 220 µL phosphate buffer solution. Plates were vigorously shaken to remove all the nonadherent bacteria. The leftover attached leftover bacteria were later fixed with 99% methanol (220 mL) and left for drying for 15 minutes. After that the wells were stained with 220 mL of crystal violet dye (50%). Distil water was used for rinsing the extra stain and plated were air dried. 220 µL glacial acetic acid (33% v/v) was used for re-solubilization of bound dye. The optical density was the measured using microplate reader at 630 nm (Biotek, USA). Experiment was run in triplicate and mean values were taken. Biofilm inhibition activity was measured using the following formula:
$\mathrm{INH} \%=100-\frac{(\mathrm{OD} 630 \mathrm{sample} \times 100)}{\mathrm{OD} 630 \mathrm{control}}$
(1)
2.5. Biodegradation lab studies using PHE as model compound
The biosurfactant used at CMC and sub CMC was produced by the same strain Klebsiella sp. KOD36. A 2% fertilizer (urea and K2HPO4 1:1, w/w) was used. All other procedure was the same as described in the above sections.
2.6. Development of soil suspension using nutrient solution for soil-water system biodegradation study
Suspension (10 g/L) of each soil, Hanford coarse sandy loam, Dello loamy sand, and Willow silty clay soil was prepared in MSM. The soil suspensions and amendments were separately autoclaved (121°C for 30 min) three times, with a 1 day interval between each autoclaving. Soil suspensions were spiked with 0.001 mCi 14C-labeled PHE (volume of acetone 0.5%, v/v) to give a final PHE concentration of 100 mg/kg soil at a specific radioactivity of 13.3 mCi/mmol of PHE. The PHE-spiked soil suspensions were then stirred for 7 days before adding biosurfactant-producing bacteria along with fertilizer and additional biosurfactant. For each soil type, unamended controls consisting of only soil without any amendment were also prepared. Different (un)amended soil treatments were further shaken for 10 days on a horizontal shaker at 120 rpm at 30°C in the dark before use in the mineralization experiments, to allow for a phenanthrene (PHE) surface equilibration between the dissolved and solid phases. Similar set of treatment was used (except MS medium) for making soil-water systems. PHE mineralization in all three different textured soils was investigated by measuring 14CO2 evolved from the biometric flasks that was trapped in a vial containing 2 ml 1M NaOH. The vials were replaced periodically and the NaOH trapped solution inside the vial was collected to measure the 14CO2 evolved using liquid scintillation counter.
## 3. Results and Discussion
3.1. Biofilm inhibition
Figure 1 indicate biofilm inhibition when 5 µg of biosurfactant was dissolved in 1 mL DMSO showed good activity against Bacillus subtilis biofilm. About 28% reduction was observed in biofilm activity (Table 2) compared to its positive control Rifampicin which showed higher (98%) biofilm inhibition activity.
3.2. Hemolytic and thrombolytic activity
The biosurfactant produced by Klebsiella sp. KOD36 showed a significant higher hemolytic activity (83.7%) than the commercial and synthetic nanoparticles. Similarly, thrombolytic activity was noted up to 50.2% (Table 2). It is quite high and can compete with other commercial synthetic thrombolytic agents because of its organic nature.
Biomedical application and potential of produced biosurfactant by Klebseilla sp. KOD36 investigated revealed that it had a unique hemolytic, thrombolytic, and biofilm inhibition activity. Such biosurfactants may have practical applications in the biomedical and therapeutical field. Recently, it has been reported that biosurfactants have the potential to act as antitumor therapeutic agents [14-17]. Application of biosurfactant in biomedical field has increased tremendously for the past couple of years. Functional properties like antifungal, antiviral and antibacterial activities make them suitable in application against various diseases and therapeutic agents [18, 19].
3.3. PHE biodegradation in soil system
Biodegradation of PHE in soil matrix microcosm experiment showed (Figure 2) that maximum (61%) PHE mineralization occurred in treatment group 4, where inoculation was performed along with biosurfactant and fertilizer in Dello loamy sand textured soil, followed by Hansford coarse sandy loam textured soil (49%), and Willow silty clay textured soil (43%). Application of biosurfactant in treatment T2 significantly improves the PHE mineralization. Maximum PHE mineralization (43%) was observed in the case of Dello loamy sand, followed by Hansford coarse sandy loam (30%), and Willow silty clay (27%). It was interesting to find out that the application of fertilizer alone to bacterial cells in treatment T3 have almost similar results as biosurfactant treatment was applied. Maximum PHE mineralization (45%) was observed in Dello loamy sand, followed by Hansford coarse sandy loam (37%), but their combination with fertilizer has significantly enhanced the total PHE mineralization. This indicated that the main factor improving the degradation was the presence of the biosurfactant rather than fertilizer. Biosurfactant application in facilitating biodegradation processes is well documented [20, 21]. The most commonly used biosurfactants are rhamnolipids from Pseudomonas species in biodegradation of various hydrocarbons like polycyclic aromatic hydrocarbons, pesticides, and other organic pollutants [22-24]. In our present state of knowledge, no study ever reported the production of rhamnolipid biosurfactant from Klebsiella sp. and its application in biodegradation of PHE.
3.4. Biodegradation of PHE in soil matrices
The results from microcosm soil system study showed improvement in PHE mineralization. It was observed (Figure 3) that maximum PHE mineralization (68%) was observed in Dello loamy sand soil-water systems, where the fertilizer was applied along with the biosurfactant and inoculation in treatment T1, followed by Hansford coarse sandy loam (67%), and Willow silty clay (59%), compared to the treatment T4 where no fertilizer and no biosurfactant were applied in inoculation. Contrary to soil matrix system experiment, biosurfactant application significantly improved the PHE mineralization, but application of fertilizer without biosurfactant to bacterial cells showed no increase in overall mineralization as in soil matrix system. Maximum PHE mineralization with biosurfactant application alone to bacterial cells in treatment T2 were observed in Dello loamy sand (47%), followed by Hansford coarse sandy loam (44%), which is equal to the PHE mineralization in Willow silty clay (43%). Fertilizer application alone to bacterial cells showed maximum mineralization in Dello loamy sand (53%), followed by Hansford coarse sandy loamy (35%), and Willow silty clay (33%).
Biostimulation experiments were conducted to investigate the effect of fertilizer in biosurfactant facilitated bioremediation in three different textured soils and soil-water systems. It was obvious from the results that biodegradation varied with the soil texture. It is likely that biosurfactants activity may vary depending on chemical and physical characteristics of soil. As Dello loamy sand textured soil has 0.7% organic matter (OM) with 79% sand contents which are higher than the Hanford coarse sandy loam (0.75% OM, 68% sand), and Willow silty clay (2.2% OM, 5% sand). It is clear that a higher OM content tends to increase the adsorption capacity of the contaminants. Also, sand content may affect adsorption and desorption capacity of the soil. Moreover, successful bioremediation of contaminants can be achieved at sufficient number of microorganisms. As microorganisms increase in number, they can enhance the mineralization rate. Microorganisms require an optimum nutrient balance required for hydrocarbon remediation of C:N:P=100:10:4. Biostimulation has been considered as an accelerating strategy in the past few years. It is believed to promote the growth and activity of microorganisms capable of degrading pollutants. Previous studies suggest that nutrient supplementation stimulates bioremediation by increasing microbial biomass [25, 26]. When a major oil spill occurs in the environment, the supply of carbon is dramatically increased, and the availability of nitrogen and phosphorus generally becomes the limiting factor for oil degradation [27, 28].
## 4. Conclusions
Soil microorganisms, particularly bacteria, exhibit a lot of potential to produce biosurfactants which are helpful in biomedical and biodegradation of hydrocarbons. Partially purified biosurfactant exhibited good hemolytic (83%), thrombolytic activity (50%), and biofilm inhibition activity (28%). Application of biosurfactant along with NPK fertilizer enhanced the PHE mineralization potential by Klebsiella sp. KOD36 in all the three different textured soils. Biosurfactant addition alone to bacterial cells had no significant difference in PHE mineralization compared to treatments where biosurfactant and fertilizer were added in soil and slurry system. Thus, biosurfactant produced by Klebsiella sp. reflects capability to be used in biomedical and environmental field applications.
## References
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2. Xue J, Zhang J, Qiao J, Lu Y. Effects of chlorination and combined UV/Cl2 treatment on endotoxin activity and inhalation toxicity of lipopolysaccharide, gram-negative bacteria and reclaimed water. Water Research. 2019;155:124-30. http://doi.org/10.1016/j.watres.2019.02.021.
3. Nogueira Felix AK, Martins JJL, Lima Almeida JG, Giro MEA, Cavalcante KF, Maciel Melo VM, et al. Purification and characterization of a biosurfactant produced by Bacillus subtilis in cashew apple juice and its application in the remediation of oil-contaminated soil. Colloids and Surfaces B: Biointerfaces. 2019;175:256-63. http://doi.org/10.1016/j.colsurfb.2018.11.062.
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5. Kale SN, Deore SL. Emulsion micro emulsion and nano emulsion: a review. Systematic Reviews in Pharmacy. 2017;8(1):39. http://doi.org/10.5530/srp.2017.1.8.
6. Usman MM, Dadrasnia A, Lim KT, Mahmud AF, Ismail S. Application of biosurfactants in environmental biotechnology; remediation of oil and heavy metal. AIMS Bioengineering. 2016;3(3):289-304. http://doi.org/10.3934/bioeng.2016.3.289.
7. Atipan S, Wiboon R-N, Suppasil M, Paweena D. Application of Biosurfactants in the Medical Field. Walailak Journal of Science and Technology (WJST). 2019;17(2). http://doi.org/10.3390/ijms17030401.
8. Singh R, Singh SK, Rathore D. Analysis of biosurfactants produced by bacteria growing on textile sludge and their toxicity evaluation for environmental application. Journal of Dispersion Science and Technology. 2020;41(4):510-22. http://doi.org/10.1080/01932691.2019.1592686.
9. Naughton P, Marchant R, Naughton V, Banat I. Microbial biosurfactants: current trends and applications in agricultural and biomedical industries. Journal of applied microbiology. 2019;127(1):12-28. http://doi.org/10.1111/jam.14243.
10. Fenibo EO, Douglas SI, Stanley HO. A review on microbial surfactants: production, classifications, properties and characterization. Journal of Advances in Microbiology. 2019:1-22. http://doi.org/10.9734/jamb/2019/v18i330170.
11. Ahmad Z, Arshad M, Asghar HN, Sheikh MA, Crowley DE. Isolation, screening and functional characterization of biosurfactant producing bacteria isolated from crude oil contaminated site. International Journal of Agriculture and Biology. 2016;18(3). http://doi.org/10.17957/IJAB/15.0126.
12. Tabasum S, Zuber M, Jamil T, Shahid M, Hussain R. Antimicrobial and pilling evaluation of the modified cellulosic fabrics using polyurethane acrylate copolymers. International Journal of Biological Macromolecules. 2013;56:99-105. http://doi.org/10.1016/j.ijbiomac.2013.01.024.
13. Stepanovic S, Cirkovic I, Ranin L, Svabic-Vlahovic M. Biofilm formation by Salmonella spp. and Listeria monocytogenes on plastic surface. Letters in applied microbiology. 2004;38(5):428-32. http://doi.org/10.1111/j.1472-765X.2004.01513.x.
14. Soberón-Chávez G. Biosurfactants: from genes to applications: Springer Science & Business Media; 2010. 364214490X.
15. Ortiz A, Teruel JA, Espuny MJ, Marqués A, Manresa Á, Aranda FJ. Interactions of a bacterial biosurfactant trehalose lipid with phosphatidylserine membranes. Chemistry and physics of lipids. 2009;158(1):46-53. http://doi.org/10.1016/j.chemphyslip.2008.11.001.
16. Ortiz A, Teruel JA, Espuny MJ, Marqués A, Manresa Á, Aranda FJ. Interactions of a Rhodococcus sp. biosurfactant trehalose lipid with phosphatidylethanolamine membranes. Biochimica et Biophysica Acta (BBA) – Biomembranes. 2008;1778(12):2806-13. http://doi.org/10.1016/j.bbamem.2008.07.016.
17. Zaragoza A, Aranda FJ, Espuny MaJ, Teruel JA, Marqués A, Manresa A, et al. Hemolytic activity of a bacterial trehalose lipid biosurfactant produced by Rhodococcus sp.: evidence for a colloid-osmotic mechanism. Langmuir. 2010;26(11):8567-72. http://doi.org/10.1021/la904637k.
18. Banat IM, Franzetti A, Gandolfi I, Bestetti G, Martinotti MG, Fracchia L, et al. Microbial biosurfactants production, applications and future potential. Applied microbiology and biotechnology. 2010;87(2):427-44. http://doi.org/10.1007/s00253-010-2589-0.
19. Rodrigues L, Banat IM, Teixeira J, Oliveira R. Biosurfactants: potential applications in medicine. Journal of Antimicrobial Chemotherapy. 2006;57(4):609-18. http://doi.org/10.1093/jac/dkl024.
20. Urum K, Pekdemir T, Gopur M. Optimum conditions for washing of crude oil-contaminated soil with biosurfactant solutions. Process Safety and Environmental Protection. 2003;81(3):203-9. http://doi.org/10.1205/095758203765639906.
21. Yateem A, Balba M, Al-Shayji Y, Al-Awadhi N. Isolation and characterization of biosurfactant-producing bacteria from oil-contaminated soil. Soil and Sediment Contamination. 2002;11(1):41-55. http://doi.org/10.1080/20025891106682.
22. Mulligan CN, Yong RN, Gibbs BF. Surfactant-enhanced remediation of contaminated soil: a review. Engineering Geology. 2001;60(1):371-80. http://doi.org/10.1016/S0013-7952(00)00117-4.
23. Megharaj M, Ramakrishnan B, Venkateswarlu K, Sethunathan N, Naidu R. Bioremediation approaches for organic pollutants: A critical perspective. Environment International. 2011;37(8):1362-75. http://doi.org/10.1016/j.envint.2011.06.003.
24. Makkar R, Cameotra SS. Biosurfactant production by a thermophilic Bacillus subtilis strain. Journal of Industrial Microbiology and Biotechnology. 1997;18(1):37-42. http://doi.org/10.1038/sj.jim.2900349.
25. Sanchez M, Campbell L, Brinker F, Owens D. Attenuation the Natural Way A former wood-preserving site offers a case study for evaluating the potential of monitored natural attenuation. Industrial Wastewater. 2000:37-42
26. Sarkar D, Ferguson M, Datta R, Birnbaum S. Bioremediation of petroleum hydrocarbons in contaminated soils: comparison of biosolids addition, carbon supplementation, and monitored natural attenuation. Environmental Pollution. 2005;136(1):187-95. http://doi.org/10.1016/j.envpol.2004.09.025.
27. Zhu X, Venosa AD, Suidan MT, Lee K. Guidelines for the bioremediation of marine shorelines and freshwater wetlands. US Environmental Protection Agency. 200128. Venosa AD, Zhu X. Biodegradation of crude oil contaminating marine shorelines and freshwater wetlands. Spill Science & Technology Bulletin. 2003;8(2):163-78. http://doi.org/10.1016/S1353-2561(03)00019-7. | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 1, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.6493080258369446, "perplexity": 27592.768991642555}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2020-40/segments/1600400232211.54/warc/CC-MAIN-20200926004805-20200926034805-00117.warc.gz"} |
https://www.physicsforums.com/threads/stability-of-system.797406/ | # Stability of system
1. Feb 12, 2015
### ranju
I have read that if pole of a function or say , a system lies in right half of a s-plane , then the system is unstable..!! But I did'nt get the logic behind it..!! What's the reasn of system being unstable if pole is lying in right half..?? Please elaborate...!!
2. Feb 12, 2015
### anorlunda
Because it will have positive feedback. Any small oscillation will grow in size without limit.
3. Feb 12, 2015
### LvW
To understand the meaning of the pole location in the s-plane one should know about the following relation between time and frequency domain:
The denominator D(s) of a systems transfer function H(s) always is identical to the characteristic polynominal P(s) of the differential equation in the time domain.
To find the time domain solution we have to calculate the roots of the characteristic equation P(s)=0.
Therefore, the roots (zeros) of the characteristic equation are identical to denominator`s zeros - equivalent to the poles of H(s).
Now - for a system to be stable we require that the real part σ of the time domain solution [exp(σT)] is negative (decaying amplitude).
That means: Also the poles of the transfer function H(s) must have a negative sign (must be in the left half of the s.plane).
4. Feb 12, 2015
### jim hardy
Look at the denominator of your transfer function while remembering that right half of plane is positive frequency.
If denominator has a term that goes to zero at some positive frequency, well, that's division by zero at that frequency
and since transfer function is output/input
a denominator of zero means it can have an output with zero input
and that's an oscillator.
So any time you get a quadratic denominator, watch out. There's a potential for oscillation.
It's been fifty years now since my controls course. Doubtless some younger member can phrase it better for you , and in today's terminology.
EDIT: oops i see Lvw already did !
old jim | {"extraction_info": {"found_math": false, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.9622464776039124, "perplexity": 1476.745685092875}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2017-34/segments/1502886120573.75/warc/CC-MAIN-20170823152006-20170823172006-00701.warc.gz"} |
https://proxieslive.com/tag/some/ | ## How can I have a villain restrain PCs in an “intelligent” way without killing or disabling some or all of them?
The party got captured during a showdown with a major villain at the end of the last session: three of them died and the survivor got trapped while trying to flee the dungeon.
All four of them can cast spells, and the villain saw them doing so during the fight. He also saw that two of them have magical companions (it’s 5e D&D, they are an Imp familiar and a Ranger’s Primal Beast) that they can summon to help. He’s a spellcaster himself, so he’s intelligent and he’ll be aware of the capabilities of an Imp familiar, which is a handy companion to have when you’re planning an escape.
He doesn’t want them dead: he wants to send them as slaves to the even more-major villain that he’s working for.
As a clever person, aware of the escape risk posed by spellcasting characters with magical companions to help, I can’t see any reason why he wouldn’t just kill the two with companions and keep the other two bound and gagged, or even unconscious, until they’re at their destination.
But this is a game, and we’re here to have fun, so I’d prefer that not to happen. I’d prefer they weren’t even gagged so they can, at least, hatch an escape plot. I’d also prefer not to have a deus ex machina solution, such as a rescue party arriving, for the same reason as it robs the PCs of their agency. It’s more fun to come up with a plan yourselves. Ideally, I’d also prefer not to fall back on a tired old trope like "the villain is so arrogant he ignores your magical powers and leaves you unbound".
Are there some good ways I can give the players a fighting chance in this situation without making my villain look like an idiot, or taking away their agency?
## What are some ways one might implement a more story-driven spell/skill acquisition?
What are some ways one might implement a more story-driven spell/skill acquisition? Hopefully in a way that isn’t a complete slog.
The idea of the players’ handbook being used as a shopping catalogue kinda ruins the immersion for me. It doesn’t make much sense that a character can go to sleep one day and then wake up the next suddenly knowing a bunch of new spells or skills if they happened to reach a new level. Especially that often those spells/skills have nothing to do with any in-game actions or backstory of the character. I’d love to see a game where the characters have to actively work towards acquiring their skills, and not just waiting till they’ve passed the next level threshold.
The question is largely about how a DnD5e system might get modified to fit my concerns because I don’t really have a group yet and 5e players are easiest to find. That said I’m open to hearing about other game systems.
In the context of 5e I was thinking of flipping the relationship between levels and skills/spells on its head and not have levels grant you skills but rather the achieving skills bumping your level up (at GM’s discretion). By "achieving skills" the character pursuing an RP way to acquire a skill. Depending on what’s going on in-game it might be super easy for some skills (e.g. you find that move that you’ve been trying to do all this time suddenly just works after enough practice) or verging on impossible for others (e.g. getting an ice-y spell for a character who is all about fire stuff). I imagine this could create a greater sense of anticipation and, ultimately, reward at the advancement of characters. Or I might be completely wrong and it’s only going to scare off potential players who just want to minmax.
## Using some homebrew i created. How to design a level 1 encounter with 7 level 1 characters
Me and my friends decided to play some dnd 5th edition. The issue is, though i am a long term DM i am only well-versed in the rules for 3.5e and Pathfinder 1st, same as Open Legend but it uses a completely different base system than the other ones.
I am essentially playing in a world that has been changed by the invention of Magitek. Technically it was discovered by some ancient ruins by the big empires expedition into the wilderness, though they honed and reverse engineered all that old tech in those ruins.
Right now my adventuring party is about to meet in the common tavern setting. All of those characters are of level 1 and consist of:
-Life Cleric
-Artificer
-Barbarian
-Monk
-The UA Pheonix Sorcerer with a few tweaks.
-A warlock with homebrew. Pact of the Vengeful Spirit as a mounted warlock kind of deal.
-Blood Hunter
Right now i want to make a small adventure playing in a neutral swiss like country, which is outside of the large and political conflicts of this world. To get the characters to bond in a more neutral environment. Since 1 Character comes from the "evil" empire and the other 3 come from it’s natural enemy. So to build up a group i decided to let them start in a neutral environment. Though i would like to introduce that little homebrew i entered into the world.
Magitek Items or rather Items with the Magitek Keyword are like magical items, but require fuel to sustain themselves for a more beneficial effect. What i was thinking of was that a Beast Tribe with enough Intelligence, probably Goblinoids, stole some shipments from the place they are currently situated at and are using that to raid the lands.
Though personally with a relatively balanced lineup of characters and essentially 7 turns in player character action economy. I personally do not know how to make an engaging encounter for them or multiple during this mini-adventure so that the players feel challenged and feel that this is an actual threat if these items get out of control. Obviously i would also not hand my players magitek items early on in the campaign. The Life Cleric is a Kleptomaniac. So should i maybe build in a failsafe ?
I’d require some good help for encounter building against overwhelming action economy in 5e as in 3.5 or pathfinder 1st i can handle it. Though there i feel it is quite confusing. Any advice is helpful here.
Thanks for the help in advance.
## Was Summon Succubus errataed at some point?
The Summon Succubus spell for Wizard, printed in Dragon 385, seems to have some issues that my group is trying to figure out. Specifically, we’ve found two versions of the Intrinsic Nature, and they are wildly different.
From the Dragon 385 PDF
Intrinsic Nature: If you haven’t given the succubus any commands by the end of your turn, it shifts 1 square and attacks you or your nearest ally within range.
and from the compendium (both offline and portable)
Intrinsic Nature: If you haven’t given the succubus any commands by the end of your turn, it shifts 1 square and attacks the nearest enemy within range that is not dominated. In addition, you are dazed until the end of your next turn.
During the discussion, we’ve found some supporting secondary information for both, but the change is not present in either the compiled 4e errata or in the errata for Dragon 385.
In favor of the PDF is, well, the initial printing, as well as the individual article for Class Acts: Wizard. There’s also this power description in an old Wizard handbook on of our members dug up from 2010
Summon Succubus (D 385) Charm, Summoning: for lash-lovers this summon adds incredible control, in the form of constant field superiority. Each target can be dominated only once, but this is often enough. A great form of control, and the intrisic nature isn’t too shabby, even if it raises a question: if the succubus attacks an ally and dominates it, i am her controller, so the round isn’t completely wasted.
Which is odd since I would never describe that intrinsic as anything other than raw downside, but does acknowledge it dominating allies, which the compendium version cannot do.
Meanwhile, in favor of the compendium version is the character builder (though notably that is not a rules source) and the later Wizard handbook from 2012
Summon Succubus. (D385) Charm, Summoning. She dominates with her attacks. She can even do outside your turn if you’re willing to take being dazed (Hint, Superior Will). Her Symbiosis effect is nice, but nothing special, although it does help to counter the CA you grant from being dazed. A fantastic power.
This references both the general amazingness of a minor>no action dominate, as well as working to mitigate the daze drawback only present in the compendium version.
However, as mentioned, we can’t find any evidence of official errata or reprinting. Does anyone know where this change was made?
## What Are Some Of The Best Practices For Mobile Strategy Optimization?
What are some of the best practices for mobile strategy optimization?
## How do I make ClickToCopy copy some text rather than string?
Consider the following example:
ClickToCopy["display text","file name"]
When I click the display text I get "file name" rather than file name without the quotes. Which doesn’t serve my purpose of quick file name access. So when I copy to some location I have to manually remove the quotes.
What should I do to make it copy the actual Text inside the String?
## I’d like to do some flashy combat stunts and still deal sneak attack damage. Are the following mechanically possible to do in game?
Feats used
• Twin Throw: As part of full attack action throw ranged weapons using one attack roll
• Ranged Feint: Feint using a ranged weapon
• Two Weapon Feint: Sacrifice an attack to use Feint
• Throw and Charge: As a full round action, you can throw a light or one-handed ranged weapon, draw another weapon, and then charge. Both attacks are made at your highest BAB with a +2 bonus to your charge attack.
Set up: Initiate Twin Throw (assumed throwing with primary and offhand) use one of the two attacks to do a Ranged Feint. If successful, the second attack can do sneak attack damage followed by what ever method you choose to deliver a the charge attack. (Roundhouse kick, uppercut, shoulder charge, clothes line, Guile’s Flash Kick) With Twin Throw you have 2 chances to do a Ranged Feint and still catch a target flat footed with the charge.
## Some addons don’t start
Some addons don’t work or rather don’t start.
For example, Alexa Rank Checker works well.
But Alive check, Anchor Text & Article Scraper does not start.
My scrapebox is up to date (2.10.19) and so are the addons.
What can I do?
Please help!
Virginie
## Please, Can someone give me some ideas on what I can do to improve this site? (any bugs?) http://students.com [closed]
Please, Can someone give me some ideas on what I can do to improve this site? (bugs?) 🤞🤞🤞 http://students.com
## Calling javascript in javascript works for some but not all scripts [migrated]
I have the following code in a script.js file that I call in my html file:
function loadScript(url) { var head = document.getElementsByTagName('head')[0]; var script = document.createElement('script'); script.type = 'text/javascript'; script.src = url; script.async = false; head.appendChild(script); } loadScript('https://polyfill.io/v3/polyfill.min.js?features=es6') loadScript('https://cdn.jsdelivr.net/npm/mathjax@3/es5/tex-mml-chtml.js') loadScript('https://cdnjs.cloudflare.com/ajax/libs/highlight.js/10.5.0/highlight.min.js') hljs.initHighlightingOnLoad();
I use this code because I want to call only one .js file in my html instead of multiple .js files.
The first two scripts that I load to call MathJax work fine. The third script to call highlight.js however does not run.
When I paste all the code from the file ‘highlight.min.js’ into the my script.js file, the javascript does run normally when I open the html.
I don’t understand why loading the ‘highlight.min.js’ file with the loadScript() does not work, or what I can do to get it to work. Any help is appreciated. | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 1, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.2854047417640686, "perplexity": 2687.0403319976213}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": false}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2021-10/segments/1614178381989.92/warc/CC-MAIN-20210308052217-20210308082217-00050.warc.gz"} |
https://online.clickview.com.au/share?sharecode=a8c55c5c | # Video Japan Under the Shoguns
For nearly 700 years, Japan was ruled by a series of military leaders known as shoguns. The first half of this clip provides a chronological ... | {"extraction_info": {"found_math": false, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.8282614946365356, "perplexity": 4772.4696787749235}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2021-17/segments/1618039560245.87/warc/CC-MAIN-20210422013104-20210422043104-00120.warc.gz"} |
http://mathhelpforum.com/differential-geometry/110731-solved-epsilon-delta-limit-r-n-supposedly-easy-but-i-need-learn-ropes-print.html | # [SOLVED] epsilon/delta limit in R^n. supposedly easy, but I need to learn the ropes
• October 26th 2009, 07:34 PM
hatsoff
[SOLVED] epsilon/delta limit in R^n. supposedly easy, but I need to learn the ropes
Quote:
Use the epsilon/delta definition to find and prove the limit:
$\lim_{\textbf{X}\to\textbf{X}_0}f(\textbf{X})=\fra c{x^3-y^3}{x-y}$, $\textbf{X}_0=(1,1)$.
My notes so far:
We have $f(\textbf{X})=\frac{x^3-y^3}{x-y}=x^2+xy+y^2,x\neq y$. So
$|f(\textbf{X})-f(\textbf{X}_0)|=|x^2+xy+y^2-x_0^2-x_0y_0-y_0^2|$
$=|(x-x_0)(x+x_0)+(y-y_0)(y+y_0)+xy-x_0y_0|$
$\leq|(x-x_0)(x+x_0)|+|(y-y_0)(y+y_0)|+|xy-x_0y_0|$
$\leq|xy-x_0y_0|+|\textbf{X}-\textbf{X}_0|(|x+x_0|+|y+y_0|)$.
That last inequality is because
$|\textbf{X}-\textbf{X}_0|=|(x-x_0,y-y_0)|=\sqrt{(x-x_0)^2+(y-y_0)^2}$
$\geq|x-x_0|,|y-y_0|$.
But I don't seem to be getting anywhere with that. I've also looked at the Cauchy-Schwarz inequality, but that doesn't offer me any obvious (to me) help.
Any ideas? Tricks? A complete solution? This isn't supposed to be a difficult problem, but it's the first of its kind which I have attempted!
EDIT: I solved it on my own. Let $\delta=-1+\sqrt{1+\frac{\epsilon}{3}}>0$ | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 10, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.8051310777664185, "perplexity": 574.6705404641107}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 20, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2014-15/segments/1397609533308.11/warc/CC-MAIN-20140416005213-00268-ip-10-147-4-33.ec2.internal.warc.gz"} |
http://math.stackexchange.com/questions/51282/what-is-an-ndr-pair | What is an NDR-Pair?
I can find sources that tell me explicitly what an NDR-pair is in terms of a map and a homotopy, but is there a good intuitive idea corresponding to, or some canonical examples that I might be able to investigate?
Thanks!
-
add comment
1 Answer
I found this article to be helpful: http://amathew.wordpress.com/2010/10/08/examples-of-cofibrations/
Basically, $(X, A)$ is an NDR-pair when there is an open $U \supset A$ (a neighborhood of $A$) such that $A$ is a deformation-retract of $U$. If $A$ is closed in $X$, then this is equivalent to the inclusion $A \hookrightarrow X$ being a cofibration.
I believe the most useful and ubiquitous examples (to an algebraic topologist) are CW-pairs $(X, A)$.
-
This isn't quite correct - in an NDR pair the deformation retraction of U onto A is also extended to a continuous homotopy of maps defined on all of X, and there is also a function $u: X \rightarrow [0,1]$ which is zero precisely on A and for which $U = u^{-1}([0,1))$. If you want an intuitive characterization that implies all of this, you can assume that $A \subset X$ has a regular neighborhood, which is a closed neighborhood that is homeomorphic to the mapping cylinder of some map $B \rightarrow A$. – Cary Mar 23 at 2:57
add comment | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 1, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.9502121806144714, "perplexity": 159.87341482976586}, "config": {"markdown_headings": false, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": false}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2014-23/segments/1405997890181.84/warc/CC-MAIN-20140722025810-00102-ip-10-33-131-23.ec2.internal.warc.gz"} |
https://cdms.astro.uni-koeln.de/classic/molecules:ism:ns-plus | J. Cernicharo, B. Lefloch, M. Agúndez, S. Bailleux, L. Margulès, E. Roueff, R. Bachiller, N. Marcelino, B. Tercero, C. Vastel, and E. Caux
reported on the
Discovery of the Ubiquitous Cation NS<sup>+</sup> in Space Confirmed by Laboratory Spectroscopy
Astrophys. J. 853, Art. No. L22 (2018).
The J = 2 – 1, 3 – 2, and 5 – 4 transitions of the closed shell thionitrosylium molecule near 100.2, 150.3, and 250.5 GHz were observed in emission with the IRAM 30 m telecope in the course of a molecular line survey of the dark cloud-type source B1b. The J = 2 – 1 transition was also observed in numerous other sources ranging from dark clouds, such as TMC-1 and L483, to low-mass protostars, such as NGC 1333 IRAS4A. It was not detected in the Orion KL hot core or compact ridge positions nor in the Sgr B2(M) or (N) hot cores. It was, however, detected in the envelope of Sgr B2. The cation is very abundant relative to the neutral (a NS/NS+ ratio in the range of 30 to 50 was determined wherever possible) compared to other diatomics.
Contributor(s): H. S. P. Müller 02, 2018
• molecules/ism/ns-plus.txt | {"extraction_info": {"found_math": false, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.9452559947967529, "perplexity": 8400.018397987618}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2021-04/segments/1610703519600.31/warc/CC-MAIN-20210119170058-20210119200058-00001.warc.gz"} |
https://www.physicsforums.com/threads/surface-charge-density-on-conducting-cone-with-point-charge-inside.579811/ | # Surface charge density on conducting cone with point charge inside
1. Feb 21, 2012
### jozegorisek
1. The problem statement, all variables and given/known data
Calculate the surface charge density on a thin insulated and uncharged cone, which has a point charge inside of it on the cone axis. Furthermore, calculate the force between the point charge and the cone.
2. Relevant equations
The relevant equation is the Poisson equation
$$\nabla^2 \phi = \delta(\mathbf{r}-\mathbf{r_0})$$
I'm not so sure about the appropriate boundary conditions although three things are certain:
1. The potential on the cone's surface is uniform (since the surface is conducting):
$$\phi|_{surface} = \phi_0$$
2. The tangential component of the electrical field on the surface is zero
3. Since the cone was uncharged in the beginning, the total charge on the surface must remain zero:
$$\oint_S \rho dS = 0$$
Since the Poisson equation is not separable in a way that the coordinate surfaces would coincide with the surfaces of the cone and since the method of images works only with plane or spherical surfaces, I presume this is a numerical problem.
3. The attempt at a solution
I see no other solution than numerical computing of the poisson equation via the finite element method.
$$\Delta f(x,y) \approx \frac{f(x-h,y) + f(x+h,y) + f(x,y-h) + f(x,y+h) - 4f(x,y)}{h^2}$$
I can imagine computing the potential inside the cone this way but I have two problems:
1. What are the correct boundary conditions for the potential?
2. How should I obtain the surface charge distribution from the numerical data of the potential?
Thank you | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 1, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.9818190932273865, "perplexity": 374.4704864330464}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2018-13/segments/1521257647556.43/warc/CC-MAIN-20180321004405-20180321024405-00140.warc.gz"} |
https://link.springer.com/chapter/10.1007%2F978-1-4419-5913-3_60 | # Kinetic Models for Cancer Imaging
• V. J. Schmidvolker
Conference paper
Part of the Advances in Experimental Medicine and Biology book series (AEMB, volume 680)
## Abstract
As tumors have distinctly different blood flow compared to that of normal tissue, the kinetic in cancerous tissue is of importance in cancer diagnosis and in assessing the efficacy of treatment. To this end, dynamic cancer imaging provides a noninvasive way for early detection of tumors and subsequent treatment planning. This paper provides an overview of currently available imaging modalities and compares different kinetic models used for analyzing tumor scans. Specific research issues that arise when analyzing dynamic imaging scans are examined and current developments in the field are highlighted.
## Keywords
Cancer imaging Detection of tumors Imaging modalities Kinetic models MRI PET SPECT
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V. J. Schmid, et al., “A Bayesian hierarchical model for the analysis of a longitudinal DCE-MRI oncology study,” Magn Reson Med, vol. 61, pp. 163–174, 2009. | {"extraction_info": {"found_math": false, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.9387626647949219, "perplexity": 19481.38701201667}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2019-35/segments/1566027313987.32/warc/CC-MAIN-20190818165510-20190818191510-00027.warc.gz"} |
https://tex.stackexchange.com/questions/169454/intersection-of-equation-with-code-frame-in-listings-package | # Intersection of equation with code frame in listings package
I used the listings package with single frame and I had an equation before my code. The problem is that the frame intersects a little with the equation and the output is ugly. This happens both when I leave a blank line bewtween the equation and the code and when I am not. How can I fix that? Why did this happenned?
Edit I:
\documentclass[12pt]{article}
\usepackage{amsmath}
\usepackage{unicode-math}
\usepackage{listings}
\begin{document}
$\displaystyle y(t)=\frac{1}{12}-\frac{e^{2t}}{4}+\frac{e^{3t}}{6}$, for $t\ge 0$
\begin{lstlisting}[frame=single,breaklines=true]
clc;
clear all;
close all;
t=0:0.1:20;
y= 1/12 -exp(2*t)/4 + exp(3*t)/6;
G=tf(1,[2 -10 12]);
[y2, t2]=step(G,t);
subplot(2,2,1)
plot(t,y);
subplot(2,2,2)
plot(t2,y2);
\end{lstlisting}
\end{document}
You are using \displaystyle for fractions that are in inline math mode. This results in big fractions that extrude below the baseline. Hence this clash.
Without \displaystyle:
They don't clash. Hence if you are using \displaystyle you need some more vertical space and we provide that through aboveskip from listings. Through aboveskip you can adjust the spacing between the listing and the paragraph above it.
Using aboveskip with a suitable dimension
\documentclass[12pt]{article}
\usepackage{amsmath}
\usepackage{unicode-math}
\usepackage{listings}
\begin{document}
$\displaystyle y(t)=\frac{1}{12}-\frac{e^{2t}}{4}+\frac{e^{3t}}{6}$, for $t\ge 0$
\begin{lstlisting}[aboveskip=\baselineskip,frame=single,breaklines=true]
clc;
clear all;
close all;
t=0:0.1:20;
y= 1/12 -exp(2*t)/4 + exp(3*t)/6;
G=tf(1,[2 -10 12]);
[y2, t2]=step(G,t);
subplot(2,2,1)
plot(t,y);
subplot(2,2,2)
plot(t2,y2);
\end{lstlisting}
\end{document}
There is similarly belowskip if you want.
As a side note, since it is matlab code, you may consider Jubobs matlab-prettifier or mcode to typeset these codes. matlab-prettifier has good features. Also refer to this question and its answers.
• Thank you very useful. What exactly does aboveskip does? Also why is this intersection there in the first place? Shouldn't normally be space between the equation and the frame? – Adam Apr 4 '14 at 13:38
• @Adam I have added some explanation. – user11232 Apr 4 '14 at 13:49
• Shouldn't the baseline change when there is displaystyle in use? And also when there is displaystyle with a table there isn't the same problem although as I understand there should be. – Adam Apr 4 '14 at 14:49
• @Adam Inline math has limitation of baseline skip. Table is different issue. – user11232 Apr 4 '14 at 14:58
• @Jubobs Indeed you did good! I myself use matlab-prettifier these days instead of mcode. :) – user11232 Jun 26 '14 at 22:20
You could just use a displaymath environment instead. Then there is no need for any adjustments:
## Notes:
• I also added basicstyle=\ttfamily for the listsings. Otherwise, the code, especially G= lined didn't look right.
## Code:
\documentclass[12pt]{article}
\usepackage{amsmath}
%\usepackage{unicode-math}
\usepackage{listings}
\begin{document}
\begin{equation*}
y(t)=\frac{1}{12}-\frac{e^{2t}}{4}+\frac{e^{3t}}{6}, \text{ for } t\ge 0
\end{equation*}
%
\begin{lstlisting}[frame=single,breaklines=true,basicstyle=\ttfamily]
clc;
clear all;
close all;
t=0:0.1:20;
y= 1/12 -exp(2*t)/4 + exp(3*t)/6;
G=tf(1,[2 -10 12]);
[y2, t2]=step(G,t);
subplot(2,2,1)
plot(t,y);
subplot(2,2,2)
plot(t2,y2);
\end{lstlisting}
\end{document}
• Thank you. I already use \ttfamily in my code along with some other options for highlighting. Here is just an example. Why without the displaymath environment the G= is like that? – Adam Apr 4 '14 at 13:41 | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 1, "mathjax_display_tex": 0, "mathjax_asciimath": 1, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.8762521743774414, "perplexity": 3532.4071442347845}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 20, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2019-43/segments/1570986700560.62/warc/CC-MAIN-20191020001515-20191020025015-00414.warc.gz"} |
http://physics.stackexchange.com/questions/47288/are-carnot-engine-efficieny-and-fourier-heat-trasmission-law-related?answertab=votes | # Are Carnot engine efficieny and Fourier heat trasmission law related?
It just occured to me that the efficiency of Carnot cycles is $\eta= \frac{T_1 - T_2}{T_1}$, that is, the efficiency decreases as the difference between reservoir temperatures decreases. On the other side, Fourier's law states that the dissipation of heat is proportional to the temperature gradient, that is, to the temperature difference.
My question, then, is: are these two results related? Do they both have a common cause?
-
It's a good question (+1), but to the best of my knowledge the answer is no. – Nathaniel Dec 21 '12 at 3:23
Fourier heat transmission law is like Hooke's law. They are empirical approximation. – Siyuan Ren Dec 21 '12 at 5:14
I do not think it is useful to look for a common cause connecting these formulae in this case. They are both expressed in terms of temperatures, and so they manifestly demonstrate their accordance with the second law of thermodynamics, but then again all laws of nature possess this feature. I do not think there is a connection that runs deeper than that. Something else to notice is that the formula for Carnot efficiency depends on the ratio of the two temperatures ($1 - T_2/T_1$), whereas a nondimensional formulation for heat conduction still depends on the temperature difference. – kleingordon Dec 22 '12 at 21:22 | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 1, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.9025856256484985, "perplexity": 354.0755122572357}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2015-27/segments/1435375098071.98/warc/CC-MAIN-20150627031818-00243-ip-10-179-60-89.ec2.internal.warc.gz"} |
https://www.physicsforums.com/threads/related-rates.230675/ | # Homework Help: Related Rates
1. Apr 22, 2008
### Sheneron
[SOLVED] Related Rates
1. The problem statement, all variables and given/known data
Two aircraft are in the vicinity of a control center. Both are at the same altitude. Plane 1 is 36 nautical miles from the center and approaching it at a rate of 410 knots. Plane 2 is 41 nautical miles from the center and approaching it at a rate of 455 knots. (One knot is 1 nautical mile per hour)
A) How close will the planes come to eachother?
B) How many minutes before the time of closest approach?
3. The attempt at a solution
I can't figure out how to solve this... I keep getting stuck here is what I have done.
$$P_1(t)^2 + P_2(t)^2 = D(t)^2$$
take the derivative
$$2P_1(t)P_1'(t) + 2P_2(t)P_2'(t) = 2D(t)D'(t)$$
and then the place where the distance would be a minimum is where D'(t) = 0, but I keep getting stuck here because I don't know either of the two P(t)s. Can someone please help me set this problem correctly? Thanks
2. Apr 22, 2008
### Sheneron
I still can't figure this out, and I think I am not going about it properly. If someone could help me set it up I would appreciate it. Thanks
3. Apr 22, 2008
### Dick
You can't do that at all unless you know something about the angle between the two planes approach paths. I'm guessing since you using Pythagoras that they are coming in at right angles? If so then just try to write P1 and P2 as explicit functions of t. They are linear functions (since velocity is constant). Try and start with P1(t). P1(0)=36mi. P1'(t)=410mi/hr, right? What does P1(t) look like?
4. Apr 22, 2008
### Sheneron
P1(t) = -410t + 36
5. Apr 22, 2008
### Sheneron
Now that I have two explicit functions of t, assuming that I did so correctly, what do I do next?
6. Apr 22, 2008
### Dick
Great! Now do P2(t) and put them into your equation.
7. Apr 22, 2008
### Sheneron
ahhh yes i just saw it I think I have it now!
Thanks... I got it | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 1, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.8633896112442017, "perplexity": 679.3802902005191}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2018-26/segments/1529267859766.6/warc/CC-MAIN-20180618105733-20180618125733-00477.warc.gz"} |
http://www.scholarpedia.org/article/Gamma_ray_bursts_theory | # Gamma ray bursts theory
Post-publication activity
Curator: Peter Mészáros
Gamma-Ray bursts (GRB) are sudden, intense flashes of gamma-rays, detected mainly in the MeV band, which for a few seconds completely overwhelm every other gamma-ray source in the sky, including the Sun. They are the brightest and most concentrated electromagnetic explosions in the Universe. Until 1997 they were undetected at any wavelengths other than gamma-rays, which are difficult to focus and hence provided poor directional information for identifying the sites of origin. The BATSE experiment on the Compton Gamma Ray Observatory (CGRO), launched in 1991, however, observed a high degree of isotropy of the GRB spatial distribution which indicated that they must be at cosmological distances. Then the Beppo-SAX satellite (1996) succeeded in discovering the previously predicted, longer duration afterglows of GRB, which appear at softer (X-ray, optical and radio) energies yielding accurate angular positions. With the latter it became possible to identify the host galaxies and to measure the cosmological redshift distances of GRB, a task later taken over by the HETE-2 satellite (2001). More recently, dramatic observational advances have been made with the Swift satellite, launched in late 2004, which has enabled fundamental new insights into the physics of GRB thanks to two new capabilities: first, the greater sensitivity of its Burst Alert Telescope (BAT; energy range 20--150 keV); and second, its ability to rapidly (within 100s) slew to the direction of the burst with its high angular resolution X-ray and UV-Optical detectors, yielding prompt and detailed multi-wavelength early afterglow spectra and light curves. The latest, far reaching insights are being obtained through the analysis of data from the recently launched (2008) Fermi satellite. For more details on the observations see Gamma Ray Bursts Observations and Gamma Ray Bursts Afterglows; for recent theoretical reviews see, e.g. Zhang, 2007; Mészáros, 2006.
From the observations, it has been clear for some time now that GRB are associated with cataclysmic stellar events. The short variability timescales $$t_{v,-3}=(t_v/10^{-3}{\rm s}) <1$$ of the prompt gamma-ray emission, together with a light travel time argument, $$r_{min} \leq c t_{v} \sim 10^7 t_{v,-3} {\rm cm}$$ indicates that the central engine dimensions are of order tens of kilometers, typical of stellar mass black holes or neutron stars. The observed fluxes and the cosmological distances (e.g. Van Paradijs, Kouveliotou and Wijers, 2000) imply an energy release of the order of a solar rest-mass, if isotropic, or about $$10^{-2}- 10^{-3}$$ solar rest mass energies when one takes into account quantitative evidence for a collimation of the early emission.
Independently of the details of the central engine, and based only on the release of the above large energies on timescales of tens of seconds or less, the observed emission of gamma-rays and the afterglow must occur via a highly relativistic, in most cases jet-like outflow. The enormous energy release in such short times in such compact regions must lead to the formation of an $$e^\pm ,\gamma$$ fireball, which will expand relativistically (Paczynski, 1986; Goodman, 1986). The fact that observed $$\epsilon_\gamma >10$$ GeV photons survive annihilation against MeV photons through $$\gamma\gamma \to e^\pm$$ constrains (Harding and Baring, 1994) the relative photon incidence angle $$\theta$$ via the threshold condition $$\epsilon_\gamma . \epsilon_t > 2 (m_e c^2)^2/(1-\cos\theta) \sim 4 (m_e c^2)^2/ \theta^2\ ,$$ and from the light cone (causality) condition, the bulk Lorentz factor $$\Gamma$$ must be $\Gamma \geq (1/\theta) \sim 10^2 [(\epsilon_\gamma /{\rm 10 GeV}) (\epsilon_t /{\rm MeV}) ]^{1/2},$ typical observed values being $$\Gamma_{2.5}=(\Gamma/300)\sim 1\ .$$ However, a smoothly expanding fireball (i.e., a laminar flow) would convert most of the explosion energy into kinetic energy of accelerated baryons, rather than into the (very high) observed photon energy, and would also produce a quasi-thermal spectrum (Shemi and Piran, 1990), whereas the usual observational description of GRB spectra is in terms of broken power laws suggesting a non-thermal origin. The most widely held view is that such non-thermal spectra arise from collisionless shocks which reconvert the expansion kinetic energy into non-thermal radiation, after the fireball has become optically thin. This is the fireball shock scenario (Rees and Mészáros, 1992; Mészáros and Rees, 1993a) The complicated light curves can be understood in terms of internal shocks (Rees and Mészáros, 1994; Sari and Piran, 1997) in the outflow itself, caused by velocity variations $$\Delta\Gamma\sim \Gamma$$ in the outflow from the central source, which occur at a radius $r_{dis} \sim 2 c t_{v} \Gamma^2 \sim 6\times 10^{12} t_{v,-3} \Gamma_{2.5}^2 ~ {\rm cm}.$ If the outflow is magnetically dominated, reconnection events leading to particle acceleration provide an alternative mechanism for the prompt emission (e.g. Lyutikov and Blandford, 2003). More recent evidence suggests that the characteristic spectral peak may be thermal in origin, possibly due to a jet photosphere, where the power law extensions may be due to shocks or multiple scattering (Thompson, Mészáros and Rees, 2007).
The external shock blast wave and its reverse shock, which occurs when the fireball ejecta unavoidably runs into the external interstellar medium or into the wind of the progenitor, results via synchrotron and inverse Compton radiation in a broad-band multi-wavelength spectrum (Mészáros and Rees, 1993b). As the fireball sweeps up more matter, the blast wave slows down and results in a subsequent, longer lasting and softer afterglow (Paczynski and Rhoads, 1994; Katz, 1994). For a burst of isotropic equivalent energy $$E_{53} = (E / {10^{53}{\rm erg}})$$ in an external medium of particle density $$n_{0}=(n/{1 \rm cm}^{-3})$$ the external shock emission reaches a maximum at a radius $r_{dec} \sim (3E/4\pi n_o m_p c^2 \Gamma^2)^{1/3} \sim 5\times 10^{16} E_{53}^{1/3} n_{0}^{-1/3} \Gamma_{2.5}^{-2/3} ~{\rm cm},$ and thereafter enters into a self-similar phase. The evolution of the external shock generates a prompt hard spectrum, which evolves as a power law in time into an optical and later a radio spectrum, while the reverse shock predicts a brief optical flash. This generic afterglow model (Mészáros and Rees, 1997) has been widely confirmed in its main features. There continue to remain, however, a number of interesting puzzles.
There are at least two distinct groups of GRB, the long ones with gamma-ray durations in excess of about 2 s, and the short ones with durations less than about 2 s. The long bursts are generally found in small star-forming galaxies, and in some cases long GRB are positionally and temporally associated with the onset of an anomalously broad-lined type Ic supernova ( SN ). Such SN result from the core collapse of stars initially more massive than about 25 solar masses, which lost most of its outer envelope (Wolf-Rayet stars). The stellar core mass is likely to exceed the Chandrasekhar limit, so it collapses either directly to a black hole (BH), or does so after a temporarily rotation-stabilized massive neutron star (NS) phase. The gravitational energy release from the subsequent accretion of gas onto the central BH or NS, or rotational energy of the compact object, is thought to provide the ultimate power for the burst (e.g. Woosley, 1993; MacFadyen and Woosley, 1999). The origin of the short bursts is less clear. There is good evidence that they are associated with old stellar populations, being found both in elliptical galaxies and in spirals or irregulars, and a likely guess (Paczynski, 1986; Eichler, Livio, Piran and Schramm, 1989) is that they result from NS-NS or NS-BH binary mergers (Ramirez-Ruiz, 2006; Lee and Ramirez-Ruiz, 2006), although other schemes involving old stars are not ruled out. The main energy source is likely to be again accretion of debris gas onto a compact central object, either a BH or a temporary massive NS which ultimately collapses to a BH, resulting from the merger or the collapse of a compact progenitor. In both long and short progenitors, accretion onto the central compact object, presumably a BH, is thought to feed the relativistic jet, which expands along the rotation axis. In the stellar collapse scenario the jet breaks through the stellar envelope, which helps to collimate it, while in the merger scenario it is expected to expand freely in a broader cone.
New insights on the burst and afterglow physics have been forthcoming from detailed X-ray light curves from Swift starting about 100 seconds after the trigger. Three of the features characterized by Swift have given rise in particular to much speculation. One of these is an initial very steep temporal decay $$F_X \propto t^{-\alpha_1}$$ with $$3 \leq \alpha_1 \leq 5\ ,$$ and an energy spectrum $$F_\nu \propto \nu^{-\beta_1}$$ with $$1 \leq \beta_1 \leq 2\ ,$$ extending up to times $$300 {\rm s} \leq t_1 \leq 500 {\rm s}\ .$$ The most widely considered explanation for this fast decay (Kumar and Panaitescu, 2000) is that it is due to off-axis emission, at $$\theta > \Gamma^{-1}\ ,$$ which due to Doppler suppression arrives after the line of sight gamma-rays have ceased, being weaker and softer than the latter. This steep X-ray decay is often followed, in Swift observations, by a flatter decay $$F_X \propto t^{-\alpha_2}$$ with $$0.2 \leq \alpha_2 \leq 0.8$$ and $$0.7 \leq \beta_2 \leq 1.2\ ,$$ at $$10^3 {\rm s} \leq t_2 \leq 10^4 {\rm s}\ .$$ Possible explanations include refreshed shocks or a continued energy input into the afterglow (Zhang et al, 2006; Nousek et al, 2006; Granot et al, 2006), varying shock parameters (Ioka et al, 2006), circumstellar gas or dust, etc. In addition, in many afterglows one or more steep X-ray flares appear superposed on the power law decay, typically between 100 s and sometimes as late as $$10^5$$ s, whose energy is $$\leq 0.01-1$$ of the prompt emission. In the case of a single flare reprocessing by a binary companion (MacFadyen, Ramirez-Ruiz and Zhang, 2006) may be a possibility. However, the rise and decay time index can be as steep as $$\pm 3$$ to 6, and especially for multiple flares, this is very hard to explain with any mechanism other than continued internal shocks or sudden dissipation (Zhang et al, 2006; Nousek et al, 2006; Krimm et al, 2007), implying a central engine activity which extends into much later times than usually expected from numerical simulations or analytical estimates.
An area of significant progress has been the connection between SN and long GRB, several of which have been discovered by Swift. Most notable has been the detection of the unusually long ($$\sim 2000$$ s), soft burst, GRB 060218 (Campana et al, 2006), associated with the nearby (z=0.033) SN2006aj, a type Ic supernova. It has been argued that the extremely long, soft power law emission may be caused by a neutron star, rather than a black hole central engine resulting from the core collapse. In any case, this was the first GRB/SN event which was was observed from the first $$\sim$$100~s in X-rays and UV/optical. The early X-ray spectrum is initially dominated by a power-law component, with an increasing black-body component which dominates after $$\approx$$3000~s. This black-body component may be due to the emergence of the SN shock through the optically thick wind of the progenitor (Waxman, Mészáros and Campana, 2007). From other GRB/SN coincidences, a trend that appears to be emerging is that in such cases the GRB is under-energetic, while the SNIc is hyper-energetic (a hypernova), or at any rate has a faster expansion rate than normal SNIc. Such GRB-related hypernovae may be significant contributors to cosmic rays in the $$10^{17}-10^{19}$$ eV range, while (long) GRB in general may accelerate, in the relativistic jet shocks, cosmic rays extending up to $$10^{20}$$ eV energies (Wang, et al, 2007; Budnik et al, 2007), and may also produce TeV-PeV energy neutrinos.
The successful launch of the Fermi Gamma-ray Space Telescope in 2008 has provided a new and powerful window into the very high energy behavior of GRBs. Roughly one GRB per week is detected with the Gamma-ray Burst Monitor (GBM, 8 keV-30 MeV), and roughly one a month is detected with the Large Area Telescope (LAT, 20 MeV-300 GeV). More than a dozen bursts have been detected by the LAT at energies above 1 GeV, including several short bursts. Among the earliest long bursts, much excitement was caused by GRB 080916C, which had 14 events ranging from 1 GeV to 13.6 GeV, and over 200 events above 100 MeV (Abdo, et al, 2009). The burst showed an interesting soft to hard to soft behavior, with a first peak in the MeV range only, but a second peak 3.5 s later with strong GeV emission. The MeV emission subsides after 55 s, but the GeV emission continues until 1400 s after the trigger. The spectra are of the Band-function (broken power law) type, with initially a hardening and then a softening of the peak energy and the high energy slope. The lack of a clearly separate second spectral component suggests a single emission emission mechanism, possibly with varying emission parameters. The presence of photons with up to 13.6 GeV coupled with a measured redshift z= 4.3 gives an estimate for the bulk Lorentz factor of $$\Gamma \geq 800\ .$$ The time lag of 3.6 s between the first GeV pulse and the first MeV pulse implies a lower limit for the quantum gravity (or Lorentz invariance violation) energy scale of $$E_{QG} \geq 1.5 \times 10^{18}$$ GeV for the first order, or $$9.4 \times 10^9$$ GeV for the second order terms (Abdo et al, 2009a).
Even more exciting were the results of the analysis of GRB 090510 (Abdo, et al, 2009b), for three completely different reasons. First, it was the first short GRB to be clearly detected in the LAT, up to 31 GeV, a record at the time of measurement. This required an even larger lower limit for the bulk Lorentz factor, $$\Gamma \geq 1200\ .$$ Second, this burst, in contrast to a number of previous ones, also showed for the first time a clear second spectral component, in addition to the usual Band-type simple broken power law . However, it is as yet unclear whether this is of leptonic or hadronic origin. Third, this burst also showed a time lag between the high and low energy emission, allowing an even stricter limit on the quantum gravity energy scale. The experimental lower limit for the first order term in this burst exceeds the Planck energy by a factor of 4, so the first order term can be ruled out. Only second order term in an effective field theory expansion can be present. This imposes restrictions on certain classes of quantum gravity theories. It is remarkable that these unimaginably high energies around the Planck scale, which are completely out of reach of even the highest energy particle accelerators such as the LHC at CERN, can nonetheless be probed with GRB observations of photons in the tens of GeV range, which give a set of robust experimental lower limits on this fundamental energy scale.
The relativistic jets of GRB are thought to be capable of accelerating cosmic rays up to GZK energies, $$E_p \sim 10^{20}$$ eV, leading to a flux at Earth comparable (Waxman, 1995; Vietri, 1995) to that observed with large extended air shower arrays such as the Pierre AUGER observatory. Both leptonic, e.g. synchrotron and inverse Compton (Sari and Esin, 2001), as well as hadronic processes (Dermer, 2002) can lead to GeV-TeV gamma-rays measurable by Fermi Gamma-ray Space Telescope, AGILE, or air Cherenkov telescopes such as HESS and VERITAS, providing useful probes of the burst physics and model parameters. Photo-meson interactions also produce neutrinos at energies ranging from sub-TeV to EeV (e.g. Waxman, 2006) which is being or will be probed with experiments such as ICECUBE, KM3NeT and ANITA. This would provide information about the fundamental interaction physics, the acceleration mechanism, the nature of the sources and their environment. Another type of non-photonic emission may be gravitational waves, especially from short GRB if these are compact (NS-NS or NS-BH) mergers (e.g. Kobayashi and Mészáros, 2002; Nakar, Gal-Yam and Fox, 2006). Such signals are being actively sought with the LIGO and VIRGO gravitational wave observatories.
Long bursts are being increasingly found at redshift distances z>5. For example, GRB 080913 had a redshift z= 6.7, comparable to the distance of the most remote galaxies and quasars, being observed at a time when the Universe was less than six percent of its present age. This burst was extremely bright, its X-ray flux exceeding for a whole day that of the most distant X-ray quasar by a factor of up to $$10^5\ .$$ Another burst, GRB 080913 was detected at a redshift z=6.7, and GRB 090423 was detected at z=8.3 (Tanvir et al, 2009). The latter is the highest confirmed spectroscopic redshift of any objects so far (July 2009), whether quasar, galaxy or GRB.
The prospect of using such high z GRB for determining cosmological parameters is tempting (Firmani, et al, 2007), but difficult, due to problems in calibrating their absolute luminosities as a yardstick. On the other hand, their intense X-ray beams are excellent for absorption spectroscopic analyses of the intervening intergalactic medium, observed at redshifts when the Universe was being re-ionized by the first stars and galaxies. They can also provide a unique means of tracing star formation rates at very high redshifts.
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• Woosley, S., 1993, Ap.J., 405, 273
• Zhang, B. et al, 2006, ApJ 642:354
• Zhang, B., 2007, ChJAA, 7:1-50
Internal references | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 1, "mathjax_display_tex": 1, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.8878215551376343, "perplexity": 3450.4658470451245}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2023-14/segments/1679296948756.99/warc/CC-MAIN-20230328011555-20230328041555-00411.warc.gz"} |
https://ares.smu.edu.sg/vutran/sensys2018-batteryless/commit/8b191fcd8e904eb78919b6c4ed71deb5ba49a3c3?view=inline | Commit 8b191fcd by Tran Huy Vu
### fix errors
parent b368aa58
... ... @@ -22,7 +22,7 @@ In this section, we present the overall functional architecture of \names, detai \label{fig:step3} \end{subfigure} \end{tabular} \caption{3-step model of \name architecture. a) Step1: The wearable send a ping packet when triggered by gestures. b) Step2: The AP receive ping packets and estimates AoA of the device, and concentrates its energy toward the device. c) Step3: The device harvests the energy and operate its sensors, and transmit the data back the the server once available.} \caption{3-step model of \name architecture. a) Step1: The wearable send a ping packet when triggered by gestures. b) Step2: The AP receives ping packets and estimates AoA of the device, and concentrates its energy toward the device. c) Step3: The device harvests the energy and operate its sensors, and transmit the data back the the server once available.} \label{fig:overview} \end{figure*} ... ... @@ -47,7 +47,7 @@ With the adoption of MIMO technologies in the latest 802.11n and 802.11ac WiFi s \end{figure} \subsection{Locating the Client Device} For beamformed energy transfer to be effective, the WiFi AP needs to know the location of the client device. More specifically, the AP does not really need to know the client's precise location; what it needs is the \emph{angular direction} of the client, \emph{relative to the AP's own location}. To compute this, the WiFi AP utilizes its antenna array to determine the AoA of any wireless transmissions from the client device. The key principle for such angle/direction estimation is that the same signal propagates different amounts of distances to reach different antennas located at the AP, and thus manifests itself in slight shifts in the signal phase changes across the different antenna elements at the AP. As the spacing between the antennas is fixed and known, by measuring the signal phase difference between adjacent antennas, we can estimate the angle of arrival of the signal (device). In practice, the presence of multipath (reflected signals) causes errors in such AoA estimation. Accordingly, we employ the state-of-the-art MUSIC signal processing algorithm~\cite{schmidt1986multiple} to obtain the AoA information for both direct path and multipath signals. Figure~\ref{fig:musicerror} shows the AoA estimation error observed in our office room setting, utilize a 4-element antenna array: we can see that the multi path effect in office environment is quite strong. At 1 location with 10 ping packets, the highest peak in a AoA spectrum is not always the correct angle of the device. However, if the system observes a sufficient number of continuous packets, it can still estimate the real angle of the device. This has been demonstrated in \cite{xiong2013arraytrack}. Note also that this functional step is needed only for mobile clients (e.g., wearable devices worn by an individual), and is unnecessary for more static settings where the location of the sensor devices are predetermined. For beamformed energy transfer to be effective, the WiFi AP needs to know the location of the client device. More specifically, the AP does not really need to know the client's precise location; what it needs is the \emph{angular direction} of the client, \emph{relative to the AP's own location}. To compute this, the WiFi AP utilizes its antenna array to determine the AoA of any wireless transmissions from the client device. The key principle for such angle/direction estimation is that the same signal propagates different amounts of distances to reach different antennas located at the AP, and thus manifests itself in slight shifts in the signal phase changes across the different antenna elements at the AP. As the spacing between the antennas is fixed and known, by measuring the signal phase difference between adjacent antennas, we can estimate the angle of arrival of the signal (device). In practice, the presence of multipath (reflected signals) causes errors in such AoA estimation. Accordingly, we employ the state-of-the-art MUSIC signal processing algorithm~\cite{schmidt1986multiple} to obtain the AoA information for both direct path and multipath signals. Figure~\ref{fig:musicerror} shows the AoA estimation error observed in our office room setting, utilize a 4-element antenna array: we can see that the multi path effect in office environment is quite strong. At 1 location with 10 ping packets, the highest peak in an AoA spectrum is not always the correct angle of the device. However, if the system observes a sufficient number of continuous packets, it can still estimate the real angle of the device. This has been demonstrated in \cite{xiong2013arraytrack}. Note also that this functional step is needed only for mobile clients (e.g., wearable devices worn by an individual), and is unnecessary for more static settings where the location of the sensor devices are predetermined. \begin{figure}[!htb] \centering ... ...
... ... @@ -53,7 +53,7 @@ work, such as ArrayTrack~\cite{xiong2013arraytrack} and Chronos~\cite{vasisht2016} have shown how to leverage active client RF transmissions, coupled with precise AoA computations to very precisely locate the client. We use similar methods in \names. Device-free localisation approaches, such as WiSee~\cite{pu2013whole}, and single AP localization approaches, such as WiSee~\cite{pu2013whole}, and single AP methods, such as Bharadia et. al~\cite{bharadia2013full}, Jain et. al~\cite{jain2011practical}, and IndoTrack~\cite{li2017} were also considered. But they were not robust enough for our arbitrary deployment ... ...
... ... @@ -89,7 +89,7 @@ Each WARP board can be connected to 4 antennas. We use one WARP board with a 4-a Therefore, for our experimental studies, we place the two antenna-array at 2 edges of a table (1 meter from each other). In our implemented system, the wearable transmits 2 types of packets: (1) a ping' packet (to aid AoA estimation) containing 1 preamble byte, 3 address bytes, 1 dummy data byte and 1 CRC byte; and (2) a data packet contains the same preamble, the address is different by 1 bit, a 2-byte packetID and 30 bytes of accelerometer data which is corresponding to 3 seconds of recorded data. \subsection{Wearable Client Device} Via our experimental studies, we are interested in not only studying the wearable device in isolation, but when it is being used by regular users. To perform such studies, we need to ensure that the wearable device can be mounted on an individual's wrist. Clearly, our current prototype isn't a true wearable device: its form-factor is simply too unwieldy for constant wear. However, to perform experimental studies, we place the wearable device in a custom-fabricated container, which is then attached to a person's wrists using multiple velcro straps (see Figure~\ref{fig:wearablecontainer}). Via our experimental studies, we are interested in not only studying the wearable device in isolation, but when it is being used by regular users. To perform such studies, we need to ensure that the wearable device can be mounted on an individual's wrist. Clearly, our current prototype isn't a true wearable device: its form-factor is simply too unwieldy for constant wear. However, to perform experimental studies, we place the wearable device in a custom-fabricated container, which is then attached to a person's wrists using multiple Velcro straps (see Figure~\ref{fig:wearablecontainer}). \subsection{Access Point \& Directional Beams} \begin{figure} ... ... @@ -112,6 +112,6 @@ Via our experimental studies, we are interested in not only studying the wearabl \noindent \textbf{Multiple Ping Packets:} In our initial implementation, the client device generated a single ping' packet whenever the motion harvester indicated significant hand motion. However, the WARP RF transmitters continue to cause interference-induced packet loss at the WARP receiver, making it unable to correctly perform the AoA update on the ping packet. Eventually, we adopted a modified packet generation process, where the client device generate multiple (10 ping packets), with an inter-packet gap of 0.6 msecs. While this slightly increased the RF power consumption after a significant movement event, it dramatically improved the reliability of correct packet reception by the WARP receiver, which was then able to correctly track the motion trajectory of the wearable throughout the duration of our studies. \noindent \textbf{Reliable Transmission of Data Packets:} Currently the WARP board we use which is controlled by matlab is slow to capture all packets. So the receiver WARP board captures and decode only the preamble and address of ping packets to estimate the AoA and to distinct different devices. We employ a separate wearable board to record acceleration data, and to make sure the WiFi harvested devices is working. \noindent \textbf{Reliable Transmission of Data Packets:} Currently the WARP board we use which is controlled by matlab is slow to capture all packets. So the receiver WARP board captures and decodes only the preamble and address of ping packets to estimate the AoA and to distinct different devices. We employ a separate wearable board to record acceleration data, and to make sure the WiFi harvested devices is working.
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https://www.cmi.ac.in/activities/show-abstract.php?absyear=2010&absref=88&abstype=sem | Seminars
12.00 noon Primal Dual algorithms for Resource Allocation Problems Sambuddha Roy IBM, Delhi. 28-10-10 Abstract We consider primal dual algorithms for resource allocation problems, that commonly occur in various real-life scenarios. The problem we consider, the {\tt ResAll} problem is a {\em covering} version of the problem commonly known as the {\tt Unsplittable Flow Problem} (UFP) on the line. The UFP problem on the line is a packing problem, and constant factor approximations are known only for certain special cases (for instance, for instances that satisfy the so-called No Bottleneck Assumption [NBA]). It is a popular conjecture that a constant factor approximation exists for the general UFP problem on the line. We show that, for the corresponding {\em covering} versions of the popular UFP problem, there {\em does} exist (polynomial time) constant factor approximations. The ResAll problem is a generalization of the Minimum Knapsack Problem, and therefore NP-hard; thus we provide polynomial time approximation algorithms for the same. Our techniques are LP based; we exploit the primal dual paradigm for LPs to provide fast combinatorial algorithms for the ResAll problem. The talk will be at an introductory level, and only basic knowledge of algorithms is required. This work is joint with Venkat Chakravarthy, Amit Kumar, Gyana Parija, and Yogish Sabharwal. | {"extraction_info": {"found_math": false, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.9928994178771973, "perplexity": 1199.4690269619714}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2018-39/segments/1537267161638.66/warc/CC-MAIN-20180925123211-20180925143611-00054.warc.gz"} |
https://www.kristybuzard.com/courses/421/ | # ECN 421: Game Theory and Economic Strategy
## What you will learn
By the end of the semester, members of the ECN 421 learning community will be able to:
1. Distinguish a strategic situation from an individual’s decision problem;
2. Describe a given strategic situation and mathematically represent it so that it can be analyzed;
3. Identify, precisely state, justify and apply the appropriate solution concept (i.e. solve the game) for a given strategic situation, including well-known games;
4. Recognize and explain the problems that arise from strategic interactions (i.e. strategic tensions)
5. Use Game Theory to understand and explain strategic interactions and the outcomes to which they lead, both within and beyond the classroom
Kristy Buzard
## FAQs
How much / what kind of math will ECN 421 involve?
We will use both algebra and a high level of logical reasoning throughout the class. For portions of the class, we will use multivariate calculus to solve maximization problems such as the following:
The profit function of an oligopolistic firm is $u_1(q_1,q_2) = (1000 - q_1 - q_2)q_1 - 100q_1$. To find the firm’s optimal response ($q_1$) as a function of its competitor’s quantity choice ($q_2$), we will take the first order condition (that is, take the partial derivative of the above expression with respect to $q_1$, set it equal to zero, and solve for $q_1$). We will also need to check second order conditions to make sure we’re at a maximum and understand when calculus can be applied and when another method must be used.
Will there be homework / problem sets?
There will be two kinds of out-of-class work. First, weekly to bi-weekly problem sets, mostly assigned out of the Watson text. These will not be collected for a grade. The second type of out-of-class work is preparatory reading for each class, on which there will be a reading quiz at the beginning of each class. See FAQ on “Style of lecture” below.
What are the attendance policies for ECN 421?
There is no explicit attendance policy, however attendance weighs heavily on the final grade indirectly. First, 25% of the course grade derives from the combination of quiz scores and participation scores. Second, participation points can only be earned if you have a team assignment, and this depends on maintaining attendance of at least 70% of class participation sessions.
What is the style of ‘lecture’ in ECN 421?
This course centers learning around students. Working most often in small teams, we will emphasize reflection and discussion of the course material and how it relates to applications, using the fundamental economic concepts of the course to help each other understand issues of interest to students.
I believe that the best use of class time is to work together on the most challenging questions with the guidance of your instructors, so students are asked to read the basic materials ahead and are quizzed at the beginning of each class to ensure everyone is prepared. We will use the Turning Point Response Card clickers for these quizzes (which are graded for accuracy) and for individual and team responses to discussion questions posed throughout each class period (which garner participation points only so that there is no anxiety about grades as we wrestle with new ideas). Short periods of lecture will be interspersed with individual reflection and team discussion to move the conversation forward and introduce key new concepts and challenges. In this way, it is my hope that the “heavy lifting” of learning is done in class at a more even pace than might otherwise be the case, with little need for cramming for exams. The learning community that we will create together will become the defining feature of the course. You can find details about the course design in the syllabus. | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 1, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.5142226219177246, "perplexity": 1165.7943365558408}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 20, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2021-43/segments/1634323585518.54/warc/CC-MAIN-20211022181017-20211022211017-00086.warc.gz"} |
https://converter.ninja/volume/us-gallons-to-imperial-cups/847-usgallon-to-brcup/ | # 847 US gallons in imperial cups
## Conversion
847 US gallons is equivalent to 11284.4005500921 imperial cups.[1]
## Conversion formula How to convert 847 US gallons to imperial cups?
We know (by definition) that: $1\mathrm{usgallon}\approx 13.3227869540638\mathrm{brcup}$
We can set up a proportion to solve for the number of imperial cups.
$1 usgallon 847 usgallon ≈ 13.3227869540638 brcup x brcup$
Now, we cross multiply to solve for our unknown $x$:
$x\mathrm{brcup}\approx \frac{847\mathrm{usgallon}}{1\mathrm{usgallon}}*13.3227869540638\mathrm{brcup}\to x\mathrm{brcup}\approx 11284.400550092038\mathrm{brcup}$
Conclusion: $847 usgallon ≈ 11284.400550092038 brcup$
## Conversion in the opposite direction
The inverse of the conversion factor is that 1 imperial cup is equal to 8.8617910677749e-05 times 847 US gallons.
It can also be expressed as: 847 US gallons is equal to $\frac{1}{\mathrm{8.8617910677749e-05}}$ imperial cups.
## Approximation
An approximate numerical result would be: eight hundred and forty-seven US gallons is about eleven thousand, two hundred and eighty-four point three nine imperial cups, or alternatively, a imperial cup is about zero times eight hundred and forty-seven US gallons.
## Footnotes
[1] The precision is 15 significant digits (fourteen digits to the right of the decimal point).
Results may contain small errors due to the use of floating point arithmetic. | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 6, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.6341221928596497, "perplexity": 3612.1515298916497}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2020-45/segments/1603107872686.18/warc/CC-MAIN-20201020105000-20201020135000-00329.warc.gz"} |
http://www.manufacturinget.org/2011/07/alkali-metals/ | # Alkali Metals
Group 1
Period 2
3
Li
3
11
Na
4
19
K
5
37
Rb
6
55
Cs
7 87Fr
The alkali metals are a series of chemical elements in the periodic table. In the modern IUPAC nomenclature, the alkali metals are called the Group 1 elements. The alkali metals include lithium (Li), sodium (Na), potassium (K), rubidium (Rb), caesium (Cs)[note 1] and francium (Fr).[4] Hydrogen (H), although nominally also a member of Group 1,[5] very rarely exhibits behaviour comparable to the alkali metals.
This group lies in the s-block of the periodic table, which means that all its elements have their outermost electron in an s-orbital. The s-block also includes alkaline earth metals, plus hydrogen and helium. The alkali metals provide one of the best examples of group trends in properties in the periodic table, with well characterized homologous behaviour down the group.
All of the alkali metals discovered, as of 2011, are naturally occurring, although francium is the second-rarest naturally occurring element. These metals share similar chemical properties: they are all highly reactive metals under standard conditions. Experiments have been conducted to attempt the synthesis of the next member of the group, which is probably ununennium (Uue), but these have all met with failure, but since ununennium is the first period 8 element and only the first element on the periodic table that has not been discovered, it is likely to be found in the near future. Note that ununennium may not be the next alkali metal due to relativistic effects.
## Characteristics
### Chemistry
Like other groups, the members of this family show patterns in its electronic configuration, especially the outermost shells, resulting in trends in chemical behaviour:
Z Element No. of electrons/shell Electron configuration
1 hydrogen 1 1s1
3 lithium 2, 1 [He]2s1
11 sodium 2, 8, 1 [Ne]3s1
19 potassium 2, 8, 8, 1 [Ar]4s1
37 rubidium 2, 8, 18, 8, 1 [Kr]5s1
55 caesium 2, 8, 18, 18, 8, 1 [Xe]6s1
87 francium 2, 8, 18, 32, 18, 8, 1 [Rn]7s1
The alkali metals are all highly reactive and are never found in elemental forms in nature. Because of this, they are usually stored in mineral oil or kerosene (paraffin oil). They also tarnish easily and have low melting points and densities.[6]
Physically, the alkali metals are mostly silver-colored, except for metallic caesium, which can have a golden tint. These elements are all soft metals of low density. Chemically, all of the alkali metals react aggressively with the halogens to form ionic salts. They all react with water to form strongly alkaline hydroxides. The vigor of reaction increases down the group. All of the atoms of alkali metals have one electron in their valence shells, hence their only way for achieving the equivalent of filled outmost electron shells is to give up one electron to an element with high electronegativity, and hence to become singly charged positive ions, i.e. cations.
Caesium reacts explosively with water even at low temperatures
The alkali metals have the lowest ionization enthalpies in their periods of the periodic table, because the removal of their single electrons from their outmost electron shells gives them the stable electron configuration of inert gases. Another way of stating this is that they all have a high electropositivity. The “second ionization potential” of all of the alkali metals is very high, since removing any electron from an atom having a noble gas configuration is difficult to do.
Series of alkali metals, stored in mineral oil (“Natrium” is sodium.)
All of the alkali metals are notable for their vigorous reactions with water, and these reactions become increasingly vigorous when going down their column in the periodic table towards the heaviest alkali metals, such as caesium. Their chemical reactions with water are as follows:
Alkali metal + water → Alkali metal hydroxide + hydrogen gas
For a typical example (M represents an alkali metal):
2 M (s) + 2 H2O (l) → 2 MOH (aq) + H2 (g)
Alkali metals form a very wide range of amalgams.[7] They tend to form ionically bonded salts with most electronegative elements on the periodic table, like caesium fluoride and sodium chloride.
### Physics
Potassium and rubidium are naturally weakly radioactive as they have naturally occurring radioisotopes (40
K
and 87
Rb
) and francium‘s only naturally occurring isotope (223
Fr
) is also radioactive with a half-life of only 22.0 minutes. Caesium was also thought to have natural radioisotopes before the discovery of francium, which made the group strange compared to the others.[citation needed]
The alkali metals show a number of trends when moving down the group – for instance: decreasing electronegativity, increasing reactivity, and decreasing melting and boiling point. Their densities generally increase, with the notable exception that potassium is less dense than sodium, and the possible exception of francium being less dense than caesium (the highly radioactive element francium only exists in microscopic quantities, so its physical properties have not been measured).
Below, hydrogen is included for comparison.
Group 1 element Standard atomic weight (u) Melting point (K) Melting point (°C) Boiling point (K) Boiling point (°C) Density (g/cm3) Electronegativity (Pauling)
Hydrogen 1.00794 14.2 −258.8 20.3 −252.7 0.00008988 2.20
Lithium 6.941 454 180.5 1615 1342 0.534 0.98
Sodium 22.98976928 370 97.8 1156 883 0.968 0.93
Potassium 39.0983 336 63.38 1032 759 0.89 0.82
Rubidium 85.4678 312 39.31 961 688 1.532 0.82
Caesium 132.9054519 301 28.44 944 671 1.93 0.79
Francium (223) 300.15 27 950.15 677 1.87 0.70
†Estimation[8]
## Hydrogen
The element hydrogen, with its solitary one electron per atom, is usually placed at the top of Group 1 of the periodic table for convenience, but hydrogen is not counted as an alkali metal. Under typical conditions, pure hydrogen exists as a diatomic gas consisting of two atoms per molecule.
The removal of the single electron of hydrogen requires considerably more energy than removal of the outer electron from the atoms of the alkali metals. As in the halogens, only one additional electron is required to fill in the outermost shell of the hydrogen atom, so hydrogen can in some circumstances behave like a halogen, forming the negative hydride ion. Binary compounds of hydrogen with the alkali metals and some transition metals have been produced in the laboratory, but these are only laboratory curiosities without much practical use. Under extremely high pressures and low temperatures, such as those found at the cores of the planets Jupiter and Saturn, hydrogen does become metallic, and it behaves like an alkali metal. This type of hydrogen is known as metallic hydrogen.
Hydrogen is sometimes considered to be an alkali metal as it, like the other alkali metals, has one valence electron; however, hydrogen rarely acts like an alkali metal, as can be seen from the data above. In fact, it is sometimes placed over lithium (due to its electron configuration),[5] sometimes carbon (due to its electronegativity)[9] and sometimes fluorine (due to its chemical properties).[9]
## History
### Lithium
Petalite
Petalite (LiAlSi4O10) was discovered in 1800 by the Brazilian chemist José Bonifácio de Andrada e Silva in a mine on the island of Utö, Sweden.[10][11][12] However, it was not until 1817 that Johan August Arfwedson, then working in the laboratory of the chemist Jöns Jakob Berzelius, detected the presence of a new element while analyzing petalite ore.[13][14][15] This element formed compounds similar to those of sodium and potassium, though its carbonate and hydroxide were less soluble in water and more alkaline.[16] Berzelius gave the alkaline material the name “lithion/lithina“, from the Greek word λιθoς (transliterated as lithos, meaning “stone”), to reflect its discovery in a solid mineral, as opposed to potassium, which had been discovered in plant ashes, and sodium which was known partly for its high abundance in animal blood. He named the metal inside the material as “lithium“.[11][15][17]
### Sodium
Caustic soda
Although sodium (sometimes called “soda” in English) has long been recognized in compounds, it was not isolated until 1807 by Humphry Davy through the electrolysis of caustic soda.[18]
### Potassium
Caustic potash
Potassium metal was first isolated in 1807 in England by Sir Humphry Davy, who derived it from caustic potash (KOH), by the use of electrolysis of the molten salt with the newly discovered voltaic pile. Potassium was the first metal that was isolated by electrolysis.[19] Later in the same year, Davy reported extraction of the metal sodium from a mineral derivative (caustic soda, NaOH, or lye), not a plant salt, by a similar technique, demonstrating the elements, and thus the salts, to be different.[18]
### Rubidium
Lepidolite
Robert Bunsen and Gustav Kirchhoff were the first to suggest finding new elements by spectrum analysis. Rubidium was discovered in 1861 by Bunsen and Kirchhoff, in Heidelberg, Germany, in the mineral lepidolite through the use of a spectroscope. Because of the bright red lines in its emission spectrum, they chose a name derived from the Latin word rubidus, dark red.[20][21]
### Caesium
In 1860, Robert Bunsen and Gustav Kirchhoff discovered caesium in the mineral water from Dürkheim, Germany. Due to the bright blue lines in its emission spectrum, they chose a name derived from the Latin word caesius, meaning sky-blue.[20][21][22][23] Caesium was the first element to be discovered spectroscopically, only one year after the invention of the spectroscope by Bunsen and Kirchhoff.[24]
### Francium
Francium (then known as ekacaesium, because it is below caesium in the periodic table) was discovered in 1939 by Marguerite Perey of the Curie Institute in Paris, France when she purified a sample of actinium-227 which had been reported to have a decay energy of 220 keV. However, Perey noticed decay particles with an energy level below 80 keV. Perey thought this decay activity might have been caused by a previously unidentified decay product, one which was separated during purification, but emerged again out of the pure actinium-227. Various tests eliminated the possibility of the unknown element being thorium, radium, lead, bismuth, or thallium. The new product exhibited chemical properties of an alkali metal (such as coprecipitating with caesium salts), which led Perey to believe that it was element 87, caused by the alpha decay of actinium-227.[25] Perey then attempted to determine the proportion of beta decay to alpha decay in actinium-227. Her first test put the alpha branching at 0.6%, a figure which she later revised to 1%.[26]
Before Perey’s discovery of francium, there were at least three erroneous and incomplete discoveries.[27][28][29][30]
### Eka-francium
The next element below francium is expected to be ununennium (Uue), element 119, although this is not certain. The synthesis of ununennium was attempted in 1985 by bombarding a target of einsteinium-254 with calcium-48 ions at the superHILAC accelerator at Berkeley, California. No atoms were identified, leading to a limiting yield of 300 nb.[31][32]
$\,^{254}_{99}\mathrm{Es} + \,^{48}_{20}\mathrm{Ca} \to \,^{302}_{119}\mathrm{Uue} ^{*} \to \ \ no\ atoms$
It is highly unlikely that this reaction will be useful given the extremely difficult task of making sufficient amounts of 254Es to make a large enough target to increase the sensitivity of the experiment to the required level, due to the rarity of the element, and extreme rarity of the isotope. However, given that ununennium is only the first period 8 element on the extended periodic table, it may well be discovered in the near future. Currently, none of the period 8 elements have been discovered yet. It is also possible that, due to drip instabilities, only the lower period 8 elements are physically possible.
Regardless of what the next element below francium actually is, it will still be known as ekafrancium, as it is below francium in the periodic table.
## Production
### Lithium
Satellite images of the Salar del Hombre Muerto, Argentina (left), and Uyuni, Bolivia (right), salt flats are rich in lithium. The lithium-rich brine is concentrated by pumping it into solar evaporation ponds (visible in the left image).
Since the end of World War II lithium production has greatly increased. The metal is separated from other elements in igneous minerals such as those above. Lithium salts are extracted from the water of mineral springs, brine pools and brine deposits. The metal is produced electrolytically from a mixture of fused lithium chloride and potassium chloride.[33]
### Sodium
Sodium was first produced commercially in 1855 by thermal reduction of sodium carbonate with carbon at 1100 °C, in what is known as the Deville process.[34]
Na2CO3 (l) + 2 C (s) → 2 Na (g) + 3 CO (g)
A process based on the reduction of sodium hydroxide was developed in 1886.[34] Sodium is now produced commercially through the electrolysis of liquid sodium chloride, based on a process patented in 1924.[35][36] This is done in a Downs Cell in which the NaCl is mixed with calcium chloride to lower the melting point below 700 °C. As calcium is less electropositive than sodium, no calcium will be formed at the anode. This method is less expensive than the previous Castner process of electrolyzing sodium hydroxide. Very pure sodium can be isolated by the thermal decomposition of sodium azide.[37]
### Potassium
Pure potassium metal may be isolated by electrolysis of its hydroxide in a process that has changed little since Davy.[38] Thermal methods also are employed in potassium production, using potassium chloride.
Potassium salts such as carnallite, langbeinite, polyhalite, potash and sylvite form extensive deposits in ancient lake and seabeds,[citation needed] making extraction of potassium salts in these environments commercially viable.
### Rubidium
Although rubidium is more abundant in Earth’s crust than caesium the limited applications and the lack of a mineral rich in rubidium limits the production of rubidium compounds to 2 to 4 tonnes per year.[39] There are several methods to separate potassium, rubidium and caesium. The fractional crystallization of a rubidium and caesium alum (Cs,Rb)Al(SO4)2·12H2O yields after 30 subsequent steps pure rubidium alum. Reports of two other methods are given in the literature the chlorostannate process and the ferrocyanide process.[39][40] For several years in the 1950s and 1960s a by-product of the potassium production called Alkarb was a main source for rubidium. Alkarb contained 21% rubidium while the rest was potassium and a small fraction of caesium.[41] Today the largest producers of caesium, for example the Tanco Mine, Manitoba, Canada, produce rubidium as by-product from pollucite.[39]
### Caesium
Pollucite
The mining of pollucite ore is a selective process and is conducted on a small scale in comparison with most metal mining operations. The ore is crushed, hand-sorted, but not usually concentrated, and then ground. Caesium is then extracted from pollucite mainly by three methods: acid digestion, alkaline decomposition, and direct reduction.[39][42]
### Francium
This sample of uraninite contains about 100,000 atoms (3.3×10−20 g) of francium-223 at any given time.[43]
Francium-223 is the result of the alpha decay of actinium-227 and can be found in trace amounts in uranium and thorium minerals.[44] In a given sample of uranium, there is estimated to be only one francium atom for every 1×1018 uranium atoms.[43] It is also calculated that there is at most 30 g of francium in the earth’s crust at any time.[45] This makes it the second rarest element in the crust after astatine.[43][46]
Francium can also be synthesized in the nuclear reaction:
197Au + 18O → 210Fr + 5 n
This process, developed by Stony Brook Physics, yields francium isotopes with masses of 209, 210, and 211,[47] which are then isolated by the magneto-optical trap (MOT).[48]
### Eka-francium
Ununennium has not been produced yet as of 2011.[31][32]
## Occurrence
### Lithium
Although lithium is widely distributed on Earth, it does not naturally occur in elemental form due to its high reactivity.[17] The total lithium content of seawater is very large and is estimated as 230 billion tonnes, where the element exists at a relatively constant concentration of 0.14 to 0.25 parts per million (ppm),[49][50] or 25 micromolar;[51] higher concentrations approaching 7 ppm are found near hydrothermal vents.[50]
### Sodium
Owing to its high reactivity, sodium is found in nature only as a compound and never as the free element. Sodium makes up about 2.6% by weight of the Earth‘s crust, making it the sixth most abundant element overall[52] and the most abundant alkali metal. Sodium is found in many different minerals, of which the most common is ordinary salt (sodium chloride), which occurs in vast quantities dissolved in seawater, as well as in solid deposits (halite). Others include amphibole, cryolite, soda niter and zeolite.[citation needed]
### Potassium
Potassium does not occur as the free element in nature due to its reactivity, but in compounds, makes up 1.5% of the weight of Earth’s crust and is the seventh most abundant chemical element.[citation needed]
### Rubidium
Rubidium is roughly as abundant as zinc and rather more common than copper. It occurs naturally in the minerals leucite, pollucite, carnallite, zinnwaldite and lepidolite.[citation needed]
### Caesium
Caesium is more abundant than antimony, cadmium, tin, tungsten, and much more abundant than mercury or silver, but 30 times less abundant than rubidium—with which it is so closely chemically associated.[53]
### Francium
Francium-223, the only naturally occurring isotope of francium,[54] is the result of the alpha decay of actinium-227 and can be found in trace amounts in uranium and thorium minerals[44] In a given sample of uranium, there is estimated to be only one francium atom for every 1×1018 uranium atoms.[43][55] It is also calculated that there is at most 30 g of francium in the earth’s crust at any time.[45] This makes it the second rarest element in the crust after astatine.[43][46]
### Eka-francium
Ununennium has not been discovered as of 2011.[31][32]
## Applications
All of the alkali metals have very many applications, some of which are mentioned in the links below:
## Biological occurrences
Lithium carbonate
• Lithium has several biological effects. Lithium carbonate is used to treat bipolar disorder (manic-depression) disorders as it works as a mood stabiliser, although there are side effects, e.g. excessive ingestion of lithium poisons the central nervous system, which is even more dangerous as the lethal dose is only just above the therapeutic dose. Lithium is present in the human body at about 30 ppb.[56]
• Sodium is an essential element for survival as its cation, Na+, is important for nerve function. Sodium is present in the human body at about 0.14%.[57]
• Potassium is also an essential element for survival as its cation, K+, is essential for nerve and heart function. Potassium is present in the human body at about 0.2%.[58]
• Rubidium has no biological role but may help stimulate metabolism, and can accumulate ahead of potassium in muscle. Rubidium is present in the body at about 4.6 ppm.[59]
• Caesium has no biological role, but can replace potassium to some extent in the body due to having similar chemical properties. Thus, caesium compounds should be avoided when possible, especially those containing radioisotopes of caesium, such as 134Cs and 137Cs. Rats fed caesium instead of potassium die. Caesium chloride (non-radioactive) has also promoted as an alternative cancer therapy,[60] but has been linked to the deaths of over 50 patients, when it was used as part of a scientifically unvalidated cancer treatment.[61] Caesium is present in the body at about 20 ppb.[62]
• Francium has no biological role[63] and would most likely be extremely toxic due to its extreme radioactivity. If francium was not radioactive, based on periodic trends it would most likely behave like caesium and would presumably be similarly toxic.[citation needed]
## Precautions
The alkali metals all react with water ever more violently and thus should all be handled with great care. Of note is the toxicity of caesium because it replaces potassium, mentioned above. Also, francium’s extreme radioactivity is a great hazard, although fortunately the greatest quantity of francium ever assembled to date is a sphere of radius 1 mm (over 300,000 neutral atoms).[64]
## Notes
1. ^ Caesium is the spelling recommended by the International Union of Pure and Applied Chemistry (IUPAC).[1] The American Chemical Society (ACS) has used the spelling cesium since 1921,[2][3] following Webster’s Third New International Dictionary.
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7. Stein, Benjamin P., Stephen G. Benka, Phillip F. Schewe, and Bertram Schwarzhild (1996). “Physics Update”. Physics Today 49 (6): 9. doi:10.1063/1.2807642. | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 1, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.7681809067726135, "perplexity": 7058.0684109724825}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.3, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2021-31/segments/1627046154457.66/warc/CC-MAIN-20210803092648-20210803122648-00559.warc.gz"} |
http://rspa.royalsocietypublishing.org/content/452/1947/769.short | Future miniaturization and mobilization of computing devices requires energy parsimonious adiabatic' computation. This is contingent on logical reversibility of computation. An example is the idea of quantum computations which are reversible except for the irreversible observation steps. We propose to study quantitatively the exchange of computational resources like time and space for irreversibility in computations. Reversible simulations of irreversible computations are memory intensive. Such (polynomial time) simulations are analysed here in terms of reversible' pebble games. We show that Bennett's pebbling strategy uses least additional space for the greatest number of simulated steps. We derive a trade-off for storage space versus irreversible erasure. Next we consider reversible computation itself. An alternative proof is provided for the precise expression of the ultimate irreversibility cost of an otherwise reversible computation without restrictions on time and space use. A time-irreversibility trade-off hierarchy in the exponential time region is exhibited. Finally, extreme time-irreversibility trade-offs for reversible computations in the thoroughly unrealistic range of computable versus non-computable time-bounds are given. | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 1, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.8869442343711853, "perplexity": 1823.4887923439414}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 20, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2014-52/segments/1418802777438.76/warc/CC-MAIN-20141217075257-00066-ip-10-231-17-201.ec2.internal.warc.gz"} |
http://clay6.com/qa/39646/www.clay6.com/qa/39646/two-ships-a-and-b-are-sailing-straight-away-from-a-fixed-point-o-along-rout | # Two ships A and B are sailing straight away from a fixed point O along routes such that $\;\angle{AOB}\;$ is always $\;120^{0}\;$ . At a certain distance , OA=8 km ,OB=6 km and the ship A is sailing at the rate of 20 km/hr while the ship B sailing at the rate of 30 km/hr . Then the distance between A and B is changing at the rate ( in km/hr ) :
$(a)\;\large\frac{260}{\sqrt{37}} \qquad(b)\;\large\frac{260}{37} \qquad(c)\;\large\frac{80}{\sqrt{37}} \qquad(d)\;\large\frac{80}{37}$ | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 1, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.9462893009185791, "perplexity": 430.16332618588433}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.3, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2018-51/segments/1544376826856.55/warc/CC-MAIN-20181215105142-20181215131142-00496.warc.gz"} |
https://worldwidescience.org/topicpages/a/aggregation+pheromone+compounds.html | #### Sample records for aggregation pheromone compounds
1. Identification of the aggregation pheromone of the melon thrips, Thrips palmi.
Science.gov (United States)
Akella, Sudhakar V S; Kirk, William D J; Lu, Yao-bin; Murai, Tamotsu; Walters, Keith F A; Hamilton, James G C
2014-01-01
The objective of this study was to identify the aggregation pheromone of the melon thrips Thrips palmi, a major pest of vegetable and ornamental plants around the world. The species causes damage both through feeding activities and as a vector of tospoviruses, and is a threat to world trade and European horticulture. Improved methods of detecting and controlling this species are needed and the identification of an aggregation pheromone will contribute to this requirement. Bioassays with a Y-tube olfactometer showed that virgin female T. palmi were attracted to the odour of live males, but not to that of live females, and that mixed-age adults of both sexes were attracted to the odour of live males, indicating the presence of a male-produced aggregation pheromone. Examination of the headspace volatiles of adult male T. palmi revealed only one compound that was not found in adult females. It was identified by comparison of its mass spectrum and chromatographic details with those of similar compounds. This compound had a structure like that of the previously identified male-produced aggregation pheromone of the western flower thrips Frankliniella occidentalis. The compound was synthesised and tested in eggplant crops infested with T. palmi in Japan. Significantly greater numbers of both males and females were attracted to traps baited with the putative aggregation pheromone compared to unbaited traps. The aggregation pheromone of T. palmi is thus identified as (R)-lavandulyl 3-methyl-3-butenoate by spectroscopic, chromatographic and behavioural analysis.
2. Identification of the aggregation pheromone of the melon thrips, Thrips palmi.
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Sudhakar V S Akella
Full Text Available The objective of this study was to identify the aggregation pheromone of the melon thrips Thrips palmi, a major pest of vegetable and ornamental plants around the world. The species causes damage both through feeding activities and as a vector of tospoviruses, and is a threat to world trade and European horticulture. Improved methods of detecting and controlling this species are needed and the identification of an aggregation pheromone will contribute to this requirement. Bioassays with a Y-tube olfactometer showed that virgin female T. palmi were attracted to the odour of live males, but not to that of live females, and that mixed-age adults of both sexes were attracted to the odour of live males, indicating the presence of a male-produced aggregation pheromone. Examination of the headspace volatiles of adult male T. palmi revealed only one compound that was not found in adult females. It was identified by comparison of its mass spectrum and chromatographic details with those of similar compounds. This compound had a structure like that of the previously identified male-produced aggregation pheromone of the western flower thrips Frankliniella occidentalis. The compound was synthesised and tested in eggplant crops infested with T. palmi in Japan. Significantly greater numbers of both males and females were attracted to traps baited with the putative aggregation pheromone compared to unbaited traps. The aggregation pheromone of T. palmi is thus identified as (R-lavandulyl 3-methyl-3-butenoate by spectroscopic, chromatographic and behavioural analysis.
3. Aggregation pheromones for monitoring the coconut rhinoceros beetle (Oryctes rhinoceros) in Jerukwangi Village, Jepara, Indonesia
Science.gov (United States)
Indriyanti, D. R.; Lutfiana, J. E.; Widiyaningrum, P.; Susilowati, E.; Slamet, M.
2018-03-01
Oryctes rhinoceros (Coleoptera: Scarabaeidae) is the most serious pest of coconut plantations in Indonesia. Jerukwangi Village is O. rhinoceros attacked one of the coconuts producing villages with more than 75% of the coconut plant population O. rhinoceros. The study aimed to monitor the population and analyze the sex ratio of O. rhinoceros that were attracted to aggregation pheromones in the field. Aggregation pheromones is a chemical compound containing Ethyl 4-methyl octanoate. The pheromone compounds were placed in traps (buckets), hung 2 meters above the ground. The traps were observed, and the beetles trapped were counted every week. In 12 weeks of monitoring, the traps captured 101 insects consist of 90.1% O. rhinoceros and 9.9% other insect species (Rhynchophorus ferrugineus and Xylotrupes gideon). This result indicates the high population of O. rhinoceros in the field. Aggregation pheromone is useful for attracting females. Rhinoceros by 61% and the males by 39%. The advantage of research is it can be used in integrated pest management (IPM) packages for monitoring of beetle population, and removal of beetles.
4. Silencing the Odorant Binding Protein RferOBP1768 Reduces the Strong Preference of Palm Weevil for the Major Aggregation Pheromone Compound Ferrugineol
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Binu Antony
2018-03-01
Full Text Available In insects, perception of the environment—food, mates, and prey—is mainly guided by chemical signals. The dynamic process of signal perception involves transport to odorant receptors (ORs by soluble secretory proteins, odorant binding proteins (OBPs, which form the first stage in the process of olfactory recognition and are analogous to lipocalin family proteins in vertebrates. Although OBPs involved in the transport of pheromones to ORs have been functionally identified in insects, there is to date no report for Coleoptera. Furthermore, there is a lack of information on olfactory perception and the molecular mechanism by which OBPs participate in the transport of aggregation pheromones. We focus on the red palm weevil (RPW Rhynchophorus ferrugineus, the most devastating quarantine pest of palm trees worldwide. In this work, we constructed libraries of all OBPs and selected antenna-specific and highly expressed OBPs for silencing through RNA interference. Aggregation pheromone compounds, 4-methyl-5-nonanol (ferrugineol and 4-methyl-5-nonanone (ferruginone, and a kairomone, ethyl acetate, were then sequentially presented to individual RPWs. The results showed that antenna-specific RferOBP1768 aids in the capture and transport of ferrugineol to ORs. Silencing of RferOBP1768, which is responsible for pheromone binding, significantly disrupted pheromone communication. Study of odorant perception in palm weevil is important because the availability of literature regarding the nature and role of olfactory signaling in this insect may reveal likely candidates representative of animal olfaction and, more generally, of molecular recognition. Knowledge of OBPs recognizing the specific pheromone ferrugineol will allow for designing biosensors for the detection of this key compound in weevil monitoring in date palm fields.
5. Aggregation pheromone of coconut rhinoceros beetle,Oryctes rhinoceros (L.) (coleoptera: Scarabaeidae).
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Hallett, R H; Perez, A L; Gries, G; Gries, R; Pierce, H D; Yue, J; Oehlschlager, A C; Gonzalez, L M; Borden, J H
1995-10-01
Male coconut rhinoceros beetles,Oryctes rhinoceros (L.), produce three sex-specific compounds, ethyl 4-methyloctanoate, ethyl 4-methylheptanoate, and 4-methyloctanoic acid, the first of which is an aggregation pheromone. Synthesis of these compounds involving conjugate addition of organocuprates to ethyl acrylate is reported. In field trapping experiments, (4S)-ethyl 4-methyloctanoate and the racemic mixture were equally attractive and 10 times more effective in attracting beetles than ethyl chrysanthemumate, a previously recommended attractant. Ethyl 4-methylheptanoate was as attractive as ethyl chrysanthemumate and more attractive than 4-methyloctanoic acid, but further studies are required before it can be classed as an aggregation pheromone. Compared to ethyl 4-methyloctanoate alone, combinations of the three male-produced compounds did not increase attraction, whereas addition of freshly rotting oil palm fruit bunches to pheromone-baited traps significantly enhanced attraction. With increasing dose, captures ofO. rhinoceros increased, but doses of 6, 9, and 18 mg/day were competitive with 30 mg/day lures. Newly designed vane traps were more effective in capturing beetles than were barrier or pitfall traps. Results of this study indicate that there is potential for using ethyl 4-methyloctanoate in operational programs to controlO. rhinoceros in oil palm plantations.
6. Pheromone-mediated aggregation in nonsocial arthropods: an evolutionary ecological perspective
NARCIS (Netherlands)
Wertheim, B.; van Baalen, E-J.A.; Dicke, M.; Vet, L.E.M.
2005-01-01
Although the use of aggregation pheromones has been reported for hundreds of nonsocial arthropod species, the evolutionary ecological aspects of this behavior have received little attention. Despite the elaborate literature on mechanisms, robust data on costs and benefits of aggregation pheromones
7. A synergistic aggregation pheromone component in the banana weevil Cosmopolites sordidus Germar 1824 (Coleoptera: Curculionidae).
Science.gov (United States)
Cerda, H; Mori, K; Nakayama, T; Jaffe, K
1998-01-01
Cosmopolites sordidus is an important pest on banana plantations worldwide. The chemistry of the aggregation pheromone of this insect has been recently resolved and here we present the first evidence from field trails that sordidin, a compound from the male released aggregation pheromone, attracts significant number of weevils only if host plant odors are also present. Sordidin attracts few insects when it is presented without the host plant tissue. However, the attractiveness of host plant tissue increases more than tenfold when it is presented simultaneously with sordidin in field traps. We confirm experimentally that sordidin may be used as part of a system for mass trapping and monitoring this insect.
8. Male-produced aggregation pheromone of Carpophilus sayi, a nitidulid vector of oak wilt disease, and pheromonal comparison with Carpophilus lugubris
Science.gov (United States)
Robert J. Bartelt; John F. Kyhl; Angie K. Ambourn; Jennifer Juzwik; Steven J. Seybold
2004-01-01
Carpophilus sayi, a nitidulid beetle vector of the oak wilt fungus, Ceratocystis fagacearum, was shown to have a male-produced aggregation pheromone. Six male-specific chemicals were identified from collections of volatiles. The two major compounds were (2E,4E,6E,8E)-3,5-dimethyl-7-ethyl-2,4,6,8- undecatetraene and (2E,4E,6E,8E...
9. Behavioural plasticity in support of a benefit for aggregation pheromone use in Drosophila melanogaster
NARCIS (Netherlands)
Wertheim, B.; Dicke, M.; Vet, L.E.M.
2002-01-01
We explored behavioural plasticity in the use of aggregation pheromone in the fruit fly Drosophila melanogaster Meigen (Diptera: Drosophilidae). Based on previous field observations, we formulated two hypotheses on a benefit of using aggregation pheromone for aggregated oviposition. One hypothesis
10. Behavioural plasticity in support of a benefit for aggregation pheromone use in Drosophila melanogaster
NARCIS (Netherlands)
Wertheim, B; Dicke, Marcel; Vet, LEM
We explored behavioural plasticity in the use of aggregation pheromone in the fruit fly Drosophila melanogaster Meigen (Diptera: Drosophilidae). Based on previous field observations, we formulated two hypotheses on a benefit of using aggregation pheromone for aggregated oviposition. One hypothesis
11. Propheromones that release pheromonal carbonyl compounds in light.
Science.gov (United States)
Liu, X; Macaulay, E D; Pickett, J A
1984-05-01
Pheromonal carbonyl compounds; (Z)-11-hexadecanal, (E)-citral, and 2-heptanone were treated with six alcohols to give acetals or ketals, some of which acted as propheromones by releasing the pheromonal carbonyl compounds in ultraviolet or simulated sunlight. Highest yields of pheromone were obtained from adducts prepared witho-nitrobenzyl alcohol ando-nitrophenylethane-1,2-diol. Adducts from (Z)-11-hexadecenal and these two alcohols were employed in lures to catch diamondback moths,Plutella xylostella (L.).
12. Effects of aggregation pheromone on individual behaviour and food web interactions: a field study on Drosophila
NARCIS (Netherlands)
Wertheim, B.; Allemand, R.; Vet, L.E.M.; Dicke, M.
2006-01-01
The effects of an aggregation pheromone on individual behaviour and food web interactions were investigated in two ecological communities, using Drosophila melanogaster and D. simulans as focal species. 2. Fruit substrates with aggregation pheromone were significantly more attractive to adult D.
13. The Lutzomyia longipalpis complex: a brief natural history of aggregation-sex pheromone communication.
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Spiegel, Carolina N; Dias, Denise B Dos Santos; Araki, Alejandra S; Hamilton, James G C; Brazil, Reginaldo P; Jones, Théresa M
2016-11-14
In this paper we review the natural history of pheromone communication and the current diversity of aggregation-sex pheromones in the sand fly Lutzomyia longipalpis. This species complex is the main vector of Leishmania infantum, the agent of visceral leishmaniasis in the Americas. The identification of variation in pheromone chemotypes combined with molecular and sound analyses have all contributed to our understanding of the extent of divergence among cryptic members of this complex. The importance of chemical signals as pre-mating barriers and drivers of speciation is discussed. Moreover, the importance of aggregation-sex pheromones as sexually selected signals is highlighted with evidence from the literature suggesting their potential role in species and mate recognition as well as mate assessment. The distinct evolutionary forces possibly involved are briefly reviewed and discussed in the context of this intriguing insect.
14. Effects of aggregation pheromone on individual behaviour and food web interactions : A field study on Drosophila
NARCIS (Netherlands)
Wertheim, Bregje; Allemand, Roland; Vet, Louise E. M.; Dicke, Marcel
1. The effects of an aggregation pheromone on individual behaviour and food web interactions were investigated in two ecological communities, using Drosophila melanogaster and D. simulatis as focal species. 2. Fruit substrates with aggregation pheromone were significantly more attractive to adult D.
15. Between-season attraction of cotton boll weevil, Anthonomus grandis Boh. (Coleoptera: Curculionidae adults by its aggregation pheromone
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Fernandes Wedson Desidério
2001-01-01
Full Text Available The present study was undertaken to investigate the attractiveness of boll weevil adults by its aggregation pheromone under winter field conditions. Two experimental fields were utilized at "Casa Branca", SP, Brazil. For each one, three areas were established near the refuge vegetation, sparated 500 m from each other. Each area was divided in three sub-areas or blocks of 100 m² to receive pheromone applications (2.5 g per block. In addition to the pre-application counting, five additional evaluations were carried out after the pheromone applicaton. Ten randomized sampling points per block were considered in each evaluation process. A. grandis adults responded immediately to the pheromone applications, and were captured for 14 days . The highest level of attractiveness was observed 24 hours after application. The application of the boll weevil aggregation pheromone during winter could increase the predation by natural enemies, due to the increase of prey availability. Chemical control can be recommended 24 hours after pheromone applications in small plots as a between-season strategy for the suppression of boll weevil adults.
16. Evidence of an aggregation pheromone in the flea beetle,Phyllotreta Cruciferae (Goeze) (Coleoptera: Chrysomelidae).
Science.gov (United States)
Peng, C; Weiss, M J
1992-06-01
Laboratory olfactometer bioassays and field trapping experiments showed that the flea beetle,Phyllotreta cruciferae (Goeze), was highly attracted by oilseed rape(Brassica napus L.) when flea beetles were on the plant. This attraction was mediated by a flea beetle-produced aggregation pheromone based upon: (1) Oilseed rape damaged mechanically, or byP. cruciferae, or by diamondback moth,Plutella xylostella (L.), did not attractP. cruciferae. (2) Contact with the plants or feeding was required for the production of aggregation pheromone because oilseed rape alone was not attractive when separated from flea beetles by a screen. (3) Equal numbers of males and females were attracted.
17. Components of male aggregation pheromone of strawberry blossom weevil, Anthonomus rubi herbst. (Coleoptera:Curculionidae).
Science.gov (United States)
Innocenzi, P J; Hall, D R; Cross, J V
2001-06-01
The strawberry blossom weevil, Anthonomus rubi, is a major pest of strawberries in the United Kingdom and continental Europe. As part of a project to develop noninsecticidal control methods, the pheromone system of this species was investigated. Comparison of volatiles produced by field-collected, overwintering individuals of each sex led to identification of three male-specific compounds--(Z)-2-(3,3-dimethylcyclohexylidene)ethanol, (cis)-1-methyl-2-(1-methylethenyl)cyclobutaneethanol, and 2-(1-methylethenyl)-5-methyl-4-hexen-1-ol (lavandulol)--in amounts of 6.1, 1.2, and 0.82 microg/day/ male. The first two compounds are components of the aggregation pheromone of the boll weevil, Anthonomus grandis, grandlure II and grandlure I, respectively. Grandlure I was the (1R,2S)-(+) enantiomer and lavandulol was a single enantiomer, although the absolute configuration was not determined. Trace amounts of the other two grandlure components (Z)-(3,3-dimethylcyclohexylidene)acetaldehyde (grandlure III) and (E)-(3,3-dimethylcyclohexylidene)acetaldehyde (grandlure IV) were also detected. (E,E)-1-(1-Methylethyl)-4-methylene-8-methyl-2,7-cyclo-decadiene (germacrene-D), a known volatile from strawberry plants, Fragaria ananassa, was collected in increased amounts in the presence of pheromone-producing weevils. Male weevils only produced pheromone on F. ananassa and not on scented mayweed, Matracaria recutita, or cow parsley, Anthriscus sylvestris, although these are known food sources. In field trials using various combinations of synthetic grandlures I, II, III, and IV and lavandulol, significantly more weevils were caught in traps baited with blends containing grandlure I and II and lavandulol than in those baited with blends without lavandulol or unbaited controls. Addition of grandlure III and IV had no significant effect on attractiveness. Horizontal sticky traps were found to be more effective than vertical sticky traps or standard boll weevil traps. In mid-season females
18. Host-Tree Monoterpenes and Biosynthesis of Aggregation Pheromones in the Bark Beetle Ips paraconfusus
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John A. Byers
2012-01-01
Full Text Available A paradigm developed in the 1970s that Ips bark beetles biosynthesize their aggregation pheromone components ipsenol and ipsdienol by hydroxylating myrcene, a host tree monoterpene. Similarly, host α-pinene was hydroxylated to a third pheromone component cis-verbenol. In 1990, however, we reported that amounts of ipsenol and ipsdienol produced by male Ips paraconfusus (Coleoptera: Scolytinae feeding in five host pine species were nearly the same, even though no detectable myrcene precursor was detected in one of these pines (Pinus sabiniana. Subsequent research showed ipsenol and ipsdienol are also biosynthesized from smaller precursors such as acetate and mevalonate, and this de novo pathway is the major one, while host tree myrcene conversion by the beetle is the minor one. We report concentrations of myrcene, α-pinene and other major monoterpenes in five pine hosts (Pinus ponderosa, P. lambertiana, P. jeffreyi, P. sabiniana, and P. contorta of I. paraconfusus. A scheme for biosynthesis of ipsdienol and ipsenol from myrcene and possible metabolites such as ipsenone is presented. Mass spectra and quantities of ipsenone are reported and its possible role in biosynthesis of aggregation pheromone. Coevolution of bark beetles and host trees is discussed in relation to pheromone biosynthesis, host plant selection/suitability, and plant resistance.
19. Sex and aggregation pheromone transport after methyl eugenol consumption in male Bactrocera papayae
International Nuclear Information System (INIS)
Hee, Alvin K.W.; Tan, K.H.
2000-01-01
Amongst at least 52 sibling species complexes in the Oriental fruit fly, Bactrocera dorsalis Hendel (Diptera: Tephritidae), B. papayae (formerly Mal B) Drew and Hancock (Drew and Hancock 1994) is beginning to emerge as an economically important insect pest which poses a severe threat to the fruit cultivation in both subtropical and tropical countries. In Malaysia, B. papayae is one of the most damaging pests which infests many commercially grown fruits (Tan and Lee 1982). Like the Oriental fruit fly and its sibling species complex, B. carambolae Drew and Hancock, B. papayae is also strongly attracted to, and compulsively feeds on, methyl eugenol (ME) (Tan 1993). Chemical analyses revealed that in B. papayae males, ME is converted to phenylpropanoids which are then selectively accumulated in the rectal gland. Of the three major volatile substances, 2-allyl-4,5-dimethoyphenol (allyl-DMP) was detected in higher quantities relative to the trans-coniferyl alcohol (4-(3-hydroxy-E-propenyl)-2-methoxyphenol) (CF) and cis-3,4-dimethoxycinnamyl alcohol (cis-DMC) (Nishida et al. 1988a, 1988b). Behavioural studies have also shown that allyl-DMP and CF function as male sex and aggregation pheromone in B. papayae (Tan and Nishida 1996, Hee and Tan 1998). Allyl-DMP was found to be the most attractive compound and cis-DMC the least attractive to the males (Tan 1996). Consumption of ME enhances the mating competitiveness of males. This is demonstrated by the strong attraction of females to conspecific ME-fed males in wind tunnel experiments (Hee and Tan 1998). In male-male mating competition for virgin females, males that fed on ME performed significantly better (Shelly and Dewire 1994, Tan and Nishida 1996). Thus it appears that ME-fed males produced signals that were more attractive. However, the characterisation and understanding of the functions of these phenylpropanoids have not been accompanied by studies of their physiological mode of transport in male flies. The current
20. 10-Methyldodecanal, a Novel Attractant Pheromone Produced by Males of the South American Cerambycid Beetle Eburodacrys vittata.
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Weliton D Silva
Full Text Available We report the identification, synthesis, and field bioassay of a novel attractant pheromone produced by males of Eburodacrys vittata (Blanchard, a South American cerambycid beetle in the subfamily Cerambycinae. Headspace volatiles from males contained a sex-specific compound, identified as 10-methyldodecanal. In a field bioassay conducted in Brazil, significant numbers of males and females were caught in traps baited with synthesized racemic 10-methyldodecanal, consistent with the aggregation-sex pheromones produced by males of many cerambycine species. This compound represents a new structural class of cerambycid pheromones, and it is the first pheromone identified for a species in the tribe Eburiini.
1. Host-tree monoterpenes and biosynthesis of aggregation pheromones in the bark beetle ips paraconfusus
Science.gov (United States)
In the 1970-80s, vapors of the common conifer tree monoterpenes, myrcene and a-pinene, were shown to serve as precursors of ipsenol, ipsdienol and cis-verbenol, aggregation pheromone components of Ips paraconfusus. A paradigm developed that Ips bark beetles utilize pre-formed monoterpene precursors ...
2. Pheromone produced by the myxobacterium Stigmatella aurantiaca.
OpenAIRE
Stephens, K; Hegeman, G D; White, D
1982-01-01
An extracellular, diffusible signaling molecule (pheromone) was produced by Stigmatella aurantiaca during fruiting body formation. The pheromone decreased the aggregation period in both the light and the dark and substituted for light in stimulating the maturation of aggregates into fruiting bodies. The cells were more sensitive to lower concentrations of pheromone in the light than in the dark, possibly explaining the stimulation of aggregation and fruiting body formation by light. The phero...
3. Synthetic Co-Attractants of the Aggregation Pheromone of the Date Palm Root Borer Oryctes agamemnon.
Science.gov (United States)
Hasni, Narjes; Pinier, Centina; Imed, Cheraief; Ouhichi, Monêem; Couzi, Philippe; Chermiti, Brahim; Frérot, Brigitte; Saïd, Imen; Rochat, Didier
2017-07-01
Laboratory and field investigations to identify and evaluate plant co-attractants of the aggregation pheromone of the date palm pest Oryctes agamemnon are reported. Volatiles emitted by freshly cut palm core and palm core with feeding males, were collected, analyzed by gas chromatography coupled to mass spectrometry and evaluated in olfactometers alone or combined with synthetic pheromone. A collection of palm odor without male effluvia was attractive alone and enhanced attraction to synthetic pheromone in an olfactometer similar to that to a collection of palm odor emitted with feeding males and containing natural pheromone. Behavioral responses to collections of palm volatiles were correlated to the amount of volatiles material in them. Enhancement of the attractiveness of the pheromone was not correlated to chemicals specific to beetle feeding. The chemicals common to the active collections extracts were benzoate esters, mostly ethyl benzoate, anisole derivatives and sesquiterpenes. Blends of the most abundant components of the extracts were evaluated for enhancement of the attractiveness of pheromone (1 μg) in olfactometers at 1 or 10 μg doses. The mixtures were further evaluated by field trapping in Tunisia at 3-10 mg/day using reference (6 mg/day) or experimental pheromone formulations. A mixture of ethyl benzoate, 4-methylanisole and farnesol (1:1:1 w/w at 6.5 mg/day) enhanced captures in pheromone baited traps in 2014 and 2015 and this mixture was as active as the natural palm bait. The practical prospect of the result for the management for O. agamemnon, and other palm beetles is discussed.
4. Orientation of boll weevil,Anthonomus grandis boh. (Coleoptera: Curculionidae), to pheromone and volatile host compound in the laboratory.
Science.gov (United States)
Dickens, J C
1986-01-01
Behavioral responses of male and female boll weevils to the aggregation pheromone, grandlure, and the major volatile of cotton, β-bisabolol, were investigated using a new dual-choice olfactometer. Dosage-response experiments revealed both males and females to be attracted by the aggregation pheromone at the 1.0 μg dosage. However, only males were attracted to β-bisabolol (1.0 μg). Both sexes were repelled by the highest dosage ofβ-bisabolol tested (10 μg). In preference experiment, males chose grandlure over β-bisabolol, while both sexes chose the combination of grandlure + β-bisabolol over β-bisabolol alone. There was some evidence for synergism between pheromone and plant odor for the females. The results correlate well with previous electrophysiological and behavioral experiments.
5. Pheromones of milkweed bugs (Heteroptera: Lygaeidae) attract wayward plant bugs: Phytocoris mirid sex pheromone.
Science.gov (United States)
Zhang, Qing-He; Aldrich, Jeffrey R
2003-08-01
The synthetic aggregation pheromone of the large milkweed bug, Oncopeltus fasciatus (Dallas) (Lygaeinae), also attracted males of the plant bug, Phytocoris difficilis Knight (Miridae). Field testing partial blends against the six-component blend comprising the Oncopeltus pheromone showed that cross-attraction of P. difficilis males was due to synergism between (E)-2-octenyl acetate and (E,E)-2,4-hexadienyl acetate. Hexyl acetate was abundant in the metathoracic scent gland (MSG) secretion of P. difficilis males, but because female P. difficilis could not initially be found in the field, further combinatorial tests were guided by prior research on the pheromones of two Phytocoris species in the western United States. The combination of hexyl, (E)-2-hexenyl, and (E)-2-octenyl acetates was as attractive to P. difficilis males as the milkweed bug pheromone, yet no milkweed bugs were drawn to this blend. Gas chromatographic (GC)-electroantennographic detection (EAD) and GC-mass spectrometric (MS) analyses of female P. difficilis MSGs determined that their secretion contained predominantly hexyl, (E)-2-hexenyl, and (E)-2-octenyl acetates (all strongly EAD-active)-the latter two compounds found only in trace amounts from males-plus five minor female-specific compounds, three of which were EAD-active. (E,E)-2,4-Hexadienyl acetate was not detected from P. difficilis females or males. The blend of the three major components, hexyl, (E)-2-hexenyl, and (E)-2-octenyl acetates (2:1.5:1 by volume), was as attractive as the blend of all six EAD-active compounds identified from females, indicating that this ternary blend constitutes the sex pheromone of P. difficilis. Hexyl acetate with (E)-2-octenyl acetate also attracted males of another species, P. breviusculus Reuter, but addition of (E)-2-hexenyl acetate and/or (E,E)-2,4-hexadienyl acetate inhibited attraction of P. breviusculus males. Attraction of P. difficilis males occurred mainly during the first half of scotophase. The
6. Combining 1,4-dimethoxybenzene, the major flower volatile of wild strawberry Fragaria vesca, with the aggregation pheromone of the strawberry blossom weevil Anthonomus rubi improves attraction
DEFF Research Database (Denmark)
Wibe, Atle; Borg-Karlson, Anna Karin; Cross, Jerry
2014-01-01
The aggregation pheromone of strawberry blossom weevil [Anthonomus rubi Herbst (Col.: Curculionidae)], a 1:4:1 blend of Grandlure I, II and racemic lavadulol, has been available for pest monitoring for several years but shows low attractancy. Attempts to control A.rubi using the pheromone alone...... were also unsuccessful. This paper reports the finding that addition of the major flower volatile from wild strawberry flowers [Fragaria vesca L. (Rosaceae)], 1,4-dimethoxybenzene (comprising 98% of the volatiles emitted from wild strawberry flowers), to the aggregation pheromone increased trap catches...... pest of strawberry....
7. Chemical compounds of the foraging recruitment pheromone in bumblebees
Science.gov (United States)
Granero, Angeles Mena; Sanz, José M. Guerra; Gonzalez, Francisco J. Egea; Vidal, José L. Martinez; Dornhaus, Anna; Ghani, Junaid; Serrano, Ana Roldán; Chittka, Lars
2005-08-01
When the frenzied and irregular food-recruitment dances of bumblebees were first discovered, it was thought that they might represent an evolutionary prototype to the honeybee waggle dance. It later emerged that the primary function of the bumblebee dance was the distribution of an alerting pheromone. Here, we identify the chemical compounds of the bumblebee recruitment pheromone and their behaviour effects. The presence of two monoterpenes and one sesquiterpene (eucalyptol, ocimene and farnesol) in the nest airspace and in the tergal glands increases strongly during foraging. Of these, eucalyptol has the strongest recruitment effect when a bee nest is experimentally exposed to it. Since honeybees use terpenes for marking food sources rather than recruiting foragers inside the nest, this suggests independent evolutionary roots of food recruitment in these two groups of bees.
8. Efficacy of aggregation pheromone in trapping red palm weevil (Rhynchophorus ferrugineus Olivier) and rhinoceros beetle (Oryctes rhinoceros Linn.) from infested coconut palms.
Science.gov (United States)
Chakravarthy, A K; Chandrashekharaiah, M; Kandakoor, Subhash B; Nagaraj, D N
2014-05-01
Red palm weevil and Rhinoceros beetle are the major pests inflicting severe damage to coconut palms. Due to ineffectiveness of the current management practices to control the two important pests on coconut, a study was conducted to know the attractiveness of red palm weevil and rhinoceros beetle to aggregation pheromone. Olfactometer studies indicated that the aggregation pheromone of red palm weevil and rhinoceros beetle attracted significantly more number of weevils (13.4 females and 7.6 male weevils) and beetles (6.5 male and 12.3 female beetles), respectively than control. Similarly, field studies found that both 750 and 1000 mg pheromone dosage lures of red palm weevil and rhinoceros beetle trapped significantly higher numbers of weevils (695.80 and 789 weevils, respectively) and beetles (98 and 108 beetles, respectively) in traps (P rhinoceros beetle population got trapped. Observations indicated activity of red palm weevil throughout the year and of rhinoceros beetle from September to March around Bangalore, South India. Pheromone traps for red palm weevil can be placed in fields from June to August and October to December and September to February for rhinoceros beetle. Population reductions of the two coleopteran pests by pheromone traps are compatible with mechanical and cultural management tools with cumulative effects.
9. Bark beetles, pityogenes bidentatus, orienting to aggregation pheromone avoid conifer monoterpene odors when flying but not when walking
Science.gov (United States)
Previous studies have provided evidence that monoterpene odors from healthy host Scotch pine (Pinus sylvestris) and non-host Norway spruce (Picea abies) significantly reduce the attraction of flying bark beetles, Pityogenes bidentatus, to their aggregation pheromone components (grandisol and cis-ver...
10. Swarming Mechanisms in the Yellow Fever Mosquito: Aggregation Pheromones are Involved in the Mating Behavior of Aedes aegypti
Science.gov (United States)
2014-12-01
behavior of Aedes aegypti Emadeldin Y. Fawaz1, Sandra A. Allan2, Ulrich R. Bernier2, Peter J. Obenauer3, and Joseph W. Diclaro II1 1Vector Biology... Aedes aegypti swarming behavior and identified associated chemical cues. Novel evidence is provided that Ae. aegypti females aggregate by means of...the isolated aggregation pheromones in controlling Ae. aegypti. Journal of Vector Ecology 39 (2): 347-354. 2014. Keyword Index: Aedes aegypti, swarm
11. Identification of the pheromone biosynthesis genes from the sex pheromone gland transcriptome of the diamondback moth, Plutella xylostella.
Science.gov (United States)
Chen, Da-Song; Dai, Jian-Qing; Han, Shi-Chou
2017-11-24
The diamondback moth was estimated to increase costs to the global agricultural economy as the global area increase of Brassica vegetable crops and oilseed rape. Sex pheromones traps are outstanding tools available in Integrated Pest Management for many years and provides an effective approach for DBM population monitoring and control. The ratio of two major sex pheromone compounds shows geographical variations. However, the limitation of our information in the DBM pheromone biosynthesis dampens our understanding of the ratio diversity of pheromone compounds. Here, we constructed a transcriptomic library from the DBM pheromone gland and identified genes putatively involved in the fatty acid biosynthesis, pheromones functional group transfer, and β-oxidation enzymes. In addition, odorant binding protein, chemosensory protein and pheromone binding protein genes encoded in the pheromone gland transcriptome, suggest that female DBM moths may receive odors or pheromone compounds via their pheromone gland and ovipositor system. Tissue expression profiles further revealed that two ALR, three DES and one FAR5 genes were pheromone gland tissue biased, while some chemoreception genes expressed extensively in PG, pupa, antenna and legs tissues. Finally, the candidate genes from large-scale transcriptome information may be useful for characterizing a presumed biosynthetic pathway of the DBM sex pheromone.
12. Pheromone biosynthesis in bark beetles.
Science.gov (United States)
Tittiger, Claus; Blomquist, Gary J
2017-12-01
Pine bark beetles rely on aggregation pheromones to coordinate mass attacks and thus reproduce in host trees. The structural similarity between many pheromone components and those of defensive tree resin led to early suggestions that pheromone components are metabolic derivatives of ingested precursors. This model has given way to our current understanding that most pheromone components are synthesized de novo. Their synthesis involves enzymes that modify products from endogenous metabolic pathways; some of these enzymes have been identified and characterized. Pheromone production is regulated in a complex way involving multiple signals, including JH III. This brief review summarizes progress in our understanding of this highly specialized metabolic process. Copyright © 2017 Elsevier Inc. All rights reserved.
13. Attraction of Cerambycid Beetles to Their Aggregation-Sex Pheromones Is Influenced by Volatiles From Host Plants of Their Larvae.
Science.gov (United States)
Wong, J C H; Zou, Y; Millar, J G; Hanks, L M
2017-06-01
Here, we describe a field experiment that tested for attraction of cerambycid beetles to odors from angiosperm hosts, and whether plant volatiles also serve to enhance attraction of beetles to their aggregation-sex pheromones. Traps were baited with a blend of synthesized chemicals that are common pheromone components of species in the subfamilies Cerambycinae and Lamiinae. The source of plant volatiles was chipped wood from trees of three angiosperm species, as well as from one nonhost, gymnosperm species. Bioassays were conducted in wooded areas of east-central Illinois. Traps were baited with the pheromone blend alone, the blend + wood chips from one tree species, wood chips alone, or a solvent control lure. Seven species of cerambycids were significantly attracted to the pheromone blend, with or without wood chips. In two cases, wood chips from angiosperms appeared to enhance attraction to pheromones, whereas they inhibited attraction in another three cases. Pine chips did not strongly influence attraction of any species. Overall, our results suggest that host plant volatiles from wood chips may improve trap catch with synthesized pheromones for some cerambycid species, but the effect is not general, necessitating case-by-case testing to determine how individual target species are affected. © The Authors 2017. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For Permissions, please email: journals.permissions@oup.com.
14. The use of aggregation pheromone to enhance dissemination of Beauveria bassiana for the control of the banana weevil in Uganda
NARCIS (Netherlands)
Tinzaara, W.; Gold, C.S.; Dicke, M.; Huis, van A.; Nankinga, C.M.; Kagezi, G.H.; Ragama, P.E.
2007-01-01
Candidate strains of Beauveria bassiana were identified for use in integrated pest management of the banana weevil Cosmopolites sordidus. Horizontal field transmission of B. bassiana between banana weevils using different delivery systems, including aggregation pheromones, was investigated. We
15. Olfactory receptor neuron responses of a longhorned beetle, Tetropium fuscum (Fabr.) (Coleoptera: Cerambycidae), to pheromone, host, and non-host volatiles.
Science.gov (United States)
MacKay, Colin A; Sweeney, Jon D; Hillier, N Kirk
2015-12-01
Longhorn wood-boring beetles (Coleoptera: Cerambycidae) use olfactory cues to find mates and hosts for oviposition. Tetropium fuscum (Fabr.) is an invasive longhorned wood-boring beetle originating from Europe that has been established in Nova Scotia, Canada, since at least 1990. This study used single sensillum recordings (SSR) to determine the response of olfactory receptor neurons (ORNs) in the antennal sensilla of male and female T. fuscum to different kinds of olfactory cues, namely host volatiles, non-host volatiles, the aggregation pheromone of T. fuscum (fuscumol), and an aggregation pheromone emitted by other species of longhorn beetles (3-hydroxyhexan-2-one). Each compound had been previously shown to elicit antennal activity in T. fuscum using electroantennography or had been shown to elicit behavioral activity in T. fuscum or other cerambycids. There have been very few SSR studies done on cerambycids, and ours is the first to compare response profiles of pheromone components as well as host and non-host volatiles. Based on SSR studies with other insects, we predicted we would find ORNs that responded to the pheromone alone (pheromone-specialists), as well as ORNs that responded only to host or non-host volatiles, i.e., separation of olfactory cue perception at the ORN level. Also, because male T. fuscum emerge earlier than females and are the pheromone-emitting sex, we predicted that the number of pheromone-sensitive ORNs would be greater in females than males. We found 140 ORNs housed within 97 sensilla that responded to at least one of the 13 compounds. Fuscumol-specific ORNs made up 15% (21/140) of all recordings, but contrary to our prediction, an additional 22 ORNs (16%) responded to fuscumol plus at least one other compound; in total, fuscumol elicited a response from 43/140 (31%) of ORNs with fuscumol-specific ORNs accounting for half of these. Thus, our prediction that pheromone reception would be segregated on specialist ORNs was only partially
16. Pheromone Autodetection: Evidence and Implications
Science.gov (United States)
Holdcraft, Robert; Rodriguez-Saona, Cesar; Stelinski, Lukasz L.
2016-01-01
Olfactory communication research with insects utilizing sex pheromones has focused on the effects of pheromones on signal receivers. Early pheromone detection studies using the silkworm moth, Bombyx mori L., and Saturniids led to the assumption that emitters, especially females, are unable to detect their own pheromone. Pheromone anosmia, i.e., the inability of females to detect their conspecific sex pheromone, was often assumed, and initially little attention was paid to female behaviors that may result from autodetection, i.e., the ability of females to detect their sex pheromone. Detection of conspecific pheromone plumes from nearby females may provide information to improve chances of mating success and progeny survival. Since the first documented example in 1972, numerous occurrences of autodetection have been observed and verified in field and laboratory studies. We summarize here a significant portion of research relating to autodetection. Electrophysiological and behavioral investigations, as well as expression patterns of proteins involved in pheromone autodetection are included. We discuss problems inherent in defining a boundary between sex and aggregation pheromones considering the occurrence of autodetection, and summarize hypothesized selection pressures favoring autodetection. Importance of including autodetection studies in future work is emphasized by complications arising from a lack of knowledge combined with expanding the use of pheromones in agriculture. PMID:27120623
17. Pheromones and exocrine glands in Isoptera.
Science.gov (United States)
Costa-Leonardo, Ana Maria; Haifig, Ives
2010-01-01
Termites are eusocial insects that have a peculiar and intriguing system of communication using pheromones. The termite pheromones are composed of a blend of chemical substances and they coordinate different social interactions or activities, including foraging, building, mating, defense, and nestmate recognition. Some of these sociochemicals are volatile, spreading in the air, and others are contact pheromones, which are transmitted by trophallaxis and grooming. Among the termite semiochemicals, the most known are alarm, trail, sex pheromones, and hydrocarbons responsible for the recognition of nestmates. The sources of the pheromones are exocrine glands located all over the termite body. The principal exocrine structures considered pheromone-producing glands in Isoptera are the frontal, mandibular, salivary or labial, sternal, and tergal glands. The frontal gland is the source of alarm pheromone and defensive chemicals, but the mandibular secretions have been little studied and their function is not well established in Isoptera. The secretion of salivary glands involves numerous chemical compounds, some of them without pheromonal function. The worker saliva contains a phagostimulating pheromone and probably a building pheromone, while the salivary reservoir of some soldiers contains defensive chemicals. The sternal gland is the only source of trail-following pheromone, whereas sex pheromones are secreted by two glandular sources, the sternal and tergal glands. To date, the termite semiochemicals have indicated that few molecules are involved in their chemical communication, that is, the same compound may be secreted by different glands, different castes and species, and for different functions, depending on the concentration. In addition to the pheromonal parsimony, recent studies also indicate the occurrence of a synergic effect among the compounds involved in the chemical communication of Isoptera. Copyright © 2010 Elsevier Inc. All rights reserved.
18. A temporal comparison of sex-aggregation pheromone gland content and dynamics of release in three members of the Lutzomyia longipalpis (Diptera: Psychodidae species complex.
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Mikel A González
2017-12-01
Full Text Available Lutzomyia longipalpis is the South American vector of Leishmania infantum, the etiologic agent of visceral leishmaniasis (VL. Male L. longipalpis produce a sex-aggregation pheromone that is critical in mating, yet very little is known about its accumulation over time or factors involved in release. This laboratory study aimed to compare accumulation of pheromone over time and determine factors that might influence release in three members of the L. longipalpis species complex.We investigated male sex-aggregation pheromone gland content at different ages and the release rate of pheromone in the presence or absence of females under different light conditions by gas chromatography-mass spectrometry (GC-MS. Pheromone gland content was determined by extraction of whole males and pheromone release rate was determined by collection of headspace volatiles. Pheromone gland content appeared age-related and pheromone began to accumulate between 6 to 12 h post eclosion and gradually increased until males were 7-9 days old. The greatest amount was detected in 9-day old Campo Grande males ((S-9-methylgermacrene-B; X ± SE: 203.5 ± 57.4 ng/male followed by Sobral 2S males (diterpene; 199.9 ± 34.3 and Jacobina males ((1S,3S,7R-3-methyl-α-himachalene; 128.8 ± 30.3 at 7 days old. Pheromone release was not continuous over time. During a 4-hour period, the greatest quantities of pheromone were released during the first hour, when wing beating activity was most intense. It was then substantially diminished for the remainder of the time. During a 24 h period, 4-5 day old male sand flies released approximately 63 ± 11% of the pheromone content of their glands, depending on the chemotype. The presence of females significantly increased pheromone release rate. The light regime under which the sand flies were held had little influence on pheromone release except on Sobral 2S chemotype.Accumulation of pheromone appears to occur at different rates in the different
19. A temporal comparison of sex-aggregation pheromone gland content and dynamics of release in three members of the Lutzomyia longipalpis (Diptera: Psychodidae) species complex.
Science.gov (United States)
González, Mikel A; Bandi, Krishna K; Bell, Melissa J; Brazil, Reginaldo P; Dilger, Erin; Guerrero, Angel; Courtenay, Orin; Hamilton, James G C
2017-12-01
Lutzomyia longipalpis is the South American vector of Leishmania infantum, the etiologic agent of visceral leishmaniasis (VL). Male L. longipalpis produce a sex-aggregation pheromone that is critical in mating, yet very little is known about its accumulation over time or factors involved in release. This laboratory study aimed to compare accumulation of pheromone over time and determine factors that might influence release in three members of the L. longipalpis species complex. We investigated male sex-aggregation pheromone gland content at different ages and the release rate of pheromone in the presence or absence of females under different light conditions by gas chromatography-mass spectrometry (GC-MS). Pheromone gland content was determined by extraction of whole males and pheromone release rate was determined by collection of headspace volatiles. Pheromone gland content appeared age-related and pheromone began to accumulate between 6 to 12 h post eclosion and gradually increased until males were 7-9 days old. The greatest amount was detected in 9-day old Campo Grande males ((S)-9-methylgermacrene-B; X ± SE: 203.5 ± 57.4 ng/male) followed by Sobral 2S males (diterpene; 199.9 ± 34.3) and Jacobina males ((1S,3S,7R)-3-methyl-α-himachalene; 128.8 ± 30.3) at 7 days old. Pheromone release was not continuous over time. During a 4-hour period, the greatest quantities of pheromone were released during the first hour, when wing beating activity was most intense. It was then substantially diminished for the remainder of the time. During a 24 h period, 4-5 day old male sand flies released approximately 63 ± 11% of the pheromone content of their glands, depending on the chemotype. The presence of females significantly increased pheromone release rate. The light regime under which the sand flies were held had little influence on pheromone release except on Sobral 2S chemotype. Accumulation of pheromone appears to occur at different rates in the different chemotypes
20. The asymmetric synthesis of (+-sitophilure, the natural form of the aggregation pheromone of Sitophilus oryzae L. and Sitophilus zeamais M.
Directory of Open Access Journals (Sweden)
Pilli Ronaldo A.
1999-01-01
Full Text Available The asymmetric synthesis of (+-sitophilure, the aggregation pheromone of Sitophilus oryzae L. and Sitophilus zeamais M., was carried out in 12 steps, 18% overall yield and 82% enantiomeric excess from the enzymatic reduction of methyl 3-oxopentanoate with S. cerevisiae in the presence of ethyl chloroacetate.
1. Effects of natural and synthetic alarm pheromone and individual pheromone components on foraging behavior of the giant Asian honey bee, Apis dorsata.
Science.gov (United States)
Li, Jianjun; Wang, Zhengwei; Tan, Ken; Qu, Yufeng; Nieh, James C
2014-10-01
Social pollinators such as honey bees face attacks from predators not only at the nest, but also during foraging. Pollinating honey bees can therefore release alarm pheromones that deter conspecifics from visiting dangerous inflorescences. However, the effect of alarm pheromone and its chemical components upon bee avoidance of dangerous food sources remains unclear. We tested the responses of giant honey bee foragers, Apis dorsata, presented with alarm pheromone at a floral array. Foragers investigated the inflorescence with natural alarm pheromone, but 3.3-fold more foragers preferred to land on the 'safe' inflorescence without alarm pheromone. Using gas chromatography-mass spectrometry analysis, we identified eight chemical components in the alarm pheromone, of which three components (1-octanol, decanal and gamma-octanoic lactone) have not previously been reported in this species. We bioassayed six major compounds and found that a synthetic mixture of these compounds elicited behaviors statistically indistinguishable from responses to natural alarm pheromone. By testing each compound separately, we show that gamma-octanoic lactone, isopentyl acetate and (E)-2-decen-1-yl acetate are active compounds that elicit significant alarm responses. Gamma-octanoic lactone elicited the strongest response to a single compound and has not been previously reported in honey bee alarm pheromone. Isopentyl acetate is widely found in the alarm pheromones of sympatric Asian honey bee species, and thus alarmed A. dorsata foragers may produce information useful for conspecifics and heterospecifics, thereby broadening the effects of alarm information on plant pollination. © 2014. Published by The Company of Biologists Ltd.
2. Pheromone gland development and pheromone production in lutzomyia longipalpis (Diptera: Psychodidae: Phlebotominae).
Science.gov (United States)
Spiegel, Carolina N; Batista-Pereira, Luciane G; Bretas, Jorge A C; Eiras, Alvaro E; Hooper, Antony M; Peixoto, Alexandre A; Soares, Maurilio J
2011-05-01
The sand fly Lutzomyia longipalpis (Lutz & Neiva) (Diptera: Psychodidae: Phlebotominae) is the main vector of American visceral leishmaniasis. Adult males produce a terpenoid sex pheromone that in some cases also acts as male aggregation pheromone. We have analyzed the correlation between male pheromone production levels and pheromone gland cell morphogenesis after adult emergence from pupae. The abdominal tergites of L. longipalpis males were dissected and fixed in glutaraldehyde for transmission electron microscopy, or the pheromone was extracted in analytical grade hexane. Pheromone chemical analysis was carried out at 3- to 6-h intervals during the first 24 h after emergence and continued daily until the seventh day. All extracts were analyzed by gas chromatography. For the morphological analysis, we used insects collected at 0-6, 9-12, 12-14, and 96 h after emergence. Ultrastructural data from 0- to 6-h-old adult males revealed smaller pheromone gland cells with small microvilli at the end apparatus. Lipid droplets and peroxisomes were absent or very rare, but a large number of mitochondria could be seen. Lipid droplets started to appear in the gland cells cytoplasm approximately 9 h after adult emergence, and their number and size increased with age, together with the presence of several peroxisomes, suggesting a role for these organelles in pheromone biosynthesis. At 12-15 h after emergence, the lipid droplets were mainly distributed near the microvilli but were smaller than those in mature older males (4 d old). Pheromone biosynthesis started around 12 h after emergence and increased continuously during the first 3 d, stabilizing thereafter, coinciding with the period when males are more able to attract females.
3. Identification and Characterization of Pheromone Receptors and Interplay between Receptors and Pheromone Binding Proteins in the Diamondback Moth, Plutella xyllostella
OpenAIRE
Sun, Mengjing; Liu, Yang; Walker, William B.; Liu, Chengcheng; Lin, Kejian; Gu, Shaohua; Zhang, Yongjun; Zhou, Jingjiang; Wang, Guirong
2013-01-01
Moths depend on olfactory cues such as sex pheromones to find and recognize mating partners. Pheromone receptors (PRs) and Pheromone binding proteins (PBPs) are thought to be associated with olfactory signal transduction of pheromonal compounds in peripheral olfactory reception. Here six candidate pheromone receptor genes in the diamondback moth, Plutella xyllostella were identified and cloned. All of the six candidate PR genes display male-biased expression, which is a typical characteristic...
4. Efficient synthesis of (+/-)-4-methyloctanoic acid, aggregation pheromone of rhinoceros beetles of the genus Oryctes (Coleoptera: Dynastidae, Scarabaeidae).
Science.gov (United States)
Ragoussis, Valentine; Giannikopoulos, Alexandros; Skoka, Efthymia; Grivas, Panagiotis
2007-06-27
(+/-)-4-Methyloctanoic acid and its ethyl ester are aggregation pheromones of many rhinoceros beetles of the genus Oryctes and are investigated for the control of these pests by olfactory trapping. A simple, economical, and high-yield (>50%) synthesis of (+/-)-4-methyloctanoic acid and its ethyl ester is presented starting from n-hexanal. The key step in this sequence is an orthoester Claisen rearrangement for the elongation of the carbon chain by two.
5. Cerambycid Beetle Species with Similar Pheromones are Segregated by Phenology and Minor Pheromone Components.
Science.gov (United States)
Mitchell, Robert F; Reagel, Peter F; Wong, Joseph C H; Meier, Linnea R; Silva, Weliton Dias; Mongold-Diers, Judith; Millar, Jocelyn G; Hanks, Lawrence M
2015-05-01
Recent research has shown that volatile sex and aggregation-sex pheromones of many species of cerambycid beetles are highly conserved, with sympatric and synchronic species that are closely related (i.e., congeners), and even more distantly related (different subfamilies), using the same or similar pheromones. Here, we investigated mechanisms by which cross attraction is averted among seven cerambycid species that are native to eastern North America and active as adults in spring: Anelaphus pumilus (Newman), Cyrtophorus verrucosus (Olivier), Euderces pini (Olivier), Neoclytus caprea (Say), and the congeners Phymatodes aereus (Newman), P. amoenus (Say), and P. varius (F.). Males of these species produce (R)-3-hydroxyhexan-2-one as their dominant or sole pheromone component. Our field bioassays support the hypothesis that cross attraction between species is averted or at least minimized by differences among species in seasonal phenology and circadian flight periods of adults, and/or by minor pheromone components that act as synergists for conspecifics and antagonists for heterospecifics.
6. Identification of the pheromone biosynthesis genes from the sex pheromone gland transcriptome of the diamondback moth, Plutella xylostella
OpenAIRE
Chen, Da-Song; Dai, Jian-Qing; Han, Shi-Chou
2017-01-01
The diamondback moth was estimated to increase costs to the global agricultural economy as the global area increase of Brassica vegetable crops and oilseed rape. Sex pheromones traps are outstanding tools available in Integrated Pest Management for many years and provides an effective approach for DBM population monitoring and control. The ratio of two major sex pheromone compounds shows geographical variations. However, the limitation of our information in the DBM pheromone biosynthesis damp...
7. Synergy of aggregation pheromone with methyl (E,E,Z)-2,4,6-decatrienoate in attraction of brown marmorated stink bug, Halyomorpha halys
Science.gov (United States)
The male-produced aggregation pheromone of the brown marmorated stink bug ((BMSB), Halyomorpha halys (Stål) (Hemiptera: Pentatomidae)), recently identified as a mixture of (3S,6S,7R,10S)-10,11-epoxy-1-bisabolen-3-ol and (3S,6S,7R,10R)-10,11-epoxy-1-bisabolen-3-ol, offers new opportunities for manage...
8. A Background of a Volatile Plant Compound Alters Neural and Behavioral Responses to the Sex Pheromone Blend in a Moth.
Science.gov (United States)
Dupuy, Fabienne; Rouyar, Angéla; Deisig, Nina; Bourgeois, Thomas; Limousin, Denis; Wycke, Marie-Anne; Anton, Sylvia; Renou, Michel
2017-01-01
Recognition of intra-specific olfactory signals within a complex environment of plant-related volatiles is crucial for reproduction in male moths. Sex pheromone information is detected by specific olfactory receptor neurons (Phe-ORNs), highly abundant on the male antenna. The information is then transmitted to the pheromone processing macroglomerular complex (MGC) within the primary olfactory center, the antennal lobe, where it is processed by local interneurons and projection neurons. Ultimately a behavioral response, orientation toward the pheromone source, is elicited. Volatile plant compounds (VPCs) are detected by other functional types of olfactory receptor neurons (ORNs) projecting in another area of the antennal lobe. However, Phe-ORNs also respond to some VPCs. Female-produced sex pheromones are emitted within a rich environment of VPCs, some of which have been shown to interfere with the detection and processing of sex pheromone information. As interference between the different odor sources might depend on the spatial and temporal features of the two types of stimuli, we investigated here behavioral and neuronal responses to a brief sex pheromone blend pulse in a VPC background as compared to a control background in the male noctuid moth Agrotis ipsilon . We observed male orientation behavior in a wind tunnel and recorded responses of Phe-ORNs and MGC neurons to a brief sex pheromone pulse within a background of individual VPCs. We also recorded the global input signal to the MGC using in vivo calcium imaging with the same stimulation protocol. We found that VPCs eliciting a response in Phe-ORNs and MGC neurons masked responses to the pheromone and decreased the contrast between background odor and the sex pheromone at both levels, whereas α-pinene did not interfere with first order processing. The calcium signal produced in response to a VPC background was tonic, lasting longer than the VPC stimulus duration, and masked entirely the pheromone response
9. Discovery and characterization of natural products that act as pheromones in fish.
Science.gov (United States)
Li, Ke; Buchinger, Tyler J; Li, Weiming
2018-06-20
Covering: up to 2018 Fish use a diverse collection of molecules to communicate with conspecifics. Since Karlson and Lüscher termed these molecules 'pheromones', chemists and biologists have joined efforts to characterize their structures and functions. In particular, the understanding of insect pheromones developed at a rapid pace, set, in part, by the use of bioassay-guided fractionation and natural product chemistry. Research on vertebrate pheromones, however, has progressed more slowly. Initially, biologists characterized fish pheromones by screening commercially available compounds suspected to act as pheromones based upon their physiological function. Such biology-driven screening has proven a productive approach to studying pheromones in fish. However, the many functions of fish pheromones and diverse metabolites that fish release make predicting pheromone identity difficult and necessitate approaches led by chemistry. Indeed, the few cases in which pheromone identification was led by natural product chemistry indicated novel or otherwise unpredicted compounds act as pheromones. Here, we provide a brief review of the approaches to identifying pheromones, placing particular emphasis on the promise of using natural product chemistry together with assays of biological activity. Several case studies illustrate bioassay-guided fractionation as an approach to pheromone identification in fish and the unexpected diversity of pheromone structures discovered by natural product chemistry. With recent advances in natural product chemistry, bioassay-guided fractionation is likely to unveil an even broader collection of pheromone structures and enable research that spans across disciplines.
10. Synthesis and metabolism of pheromones and pheromone analogues
International Nuclear Information System (INIS)
Ding, Y.S.
1987-01-01
[9, 10- 3 H 2 ]Z9-14:Ac was synthesized at high specific activity ( 3 H, 58 Ci/mmole) by partial tritiation of the corresponding alkyne and was converted to the labeled Z9-14:OH and Z9-14:Al to study tissue specificity of acetate esterase (E), alcohol oxidase (OX), and aldehyde dehydrogenase (ALDH) in male and female Heliothis virescens. Soluble and membrane-associated enzyme activities were determined by radio-TLC assays. Compounds of the tritium-labeled Z11-16 series were synthesized and their in vitro fates examined as well. In order to achieve an alternative approach in which (1) pheromone receptor proteins would be stoichiometrically and irreversibly modified, or (2) pheromone-catabolizing enzymes are inactivated by tight-binding or irreversible inhibitors, we have designed analogues of pheromones of lepidopterous insect pests and assayed their biological activity in vitro and in vivo. Various fluorinated molecules such as acyl fluorides, fluoroolefins, 2-fluoro aldehydes, 2,2-difluoro aldehydes and trifluoromethyl ketones were synthesized. The synthesis of some other functional groups such as cyclopropanones, cyclopropanols, cyclopropyl carbinols, cyclopropyl aldehydes and Michael acceptors will also be discussed
11. Differential recognition of geometric isomers by the boll weevil,Anthonomus grandis Boh. (Coleoptera: Curculionidae): Evidence for only three essential components in aggregation pheromone.
Science.gov (United States)
Dickens, J C; Prestwich, G D
1989-02-01
For two decades, the aggregation pheromone of the boll weevil,Anthonomus grandis Boh. (Coleoptera: Curculionidae), was thought to consist of four compounds: I [(+)-(Z)-2-isopropenyl-1-methylcyclobutane ethanol]; II [(Z)-3,3-dimethyl-Δ(I,β)-cyclohexane ethanol]; III [(Z)-3,3-dimethyl-Δ(1,α)-cyclohexane acetaldehyde); and IV [(E)-3,3-dimethyl-Δ(1,α)-cyclohexane acetaldehyde). Evidence is presented from behavioral and electrophysiological studies to show that only three of these components, I, II, and IV, are essential for attraction. Competitive field tests, in which each possible three-component blend was tested against the four-component mixture, demonstrated that omission of I, II. or IV resulted in decreased trap captures (P < 0.01). Trap captures by these blends lacking I, II, or IV resembled those by the hexane solvent alone in a similar experiment. However, omission of III did not significantly alter field attractiveness of the blend. Dosage-response curves constructed from electroantennogram responses of both males and females to serial dilutions of III, IV, and a 50∶50 mixture of the geometric isomers III and IV showed both sexes to be 10- to 100-fold more sensitive to IV than III. Data from the electrophysiological studies were consistent with a single acceptor type for the (E)-cyclohexylidene aldehyde, IV, for males, and possibly one or two acceptor types for III and IV for females. Possible roles for the (Z)-cyclohexylidene aldehyde, III, and implications for the pheromonal attractant currently used in boll weevil eradication/suppression programs are discussed.
12. Behavioral and neurosensory responses of the boll weevil,Anthonomus grandis Boh. (Coleoptera: Curculionidae), to fluorinated analogs of aldehyde components of its pheromone.
Science.gov (United States)
Dickens, J C; Prestwich, G D; Sun, W C
1991-06-01
Competitive field tests with α-fluorinated analogs of compounds III and IV (III-α-F and IV-α-F, respectively) of the boll weevil,Anthonomus grandis Boh., aggregation pheromone showed these compounds, when combined with the other pheromone components [(±)-I and II], to be as attractive as grandlure [(+)-I, II, and III+IV]. Dose-response curves constructed from electroantennograms of male boll weevils to serial stimulus loads of III, IV, III-α-F, IV-α-F, and the corresponding acyl fluorinated analogs (III-acyl-F and IV-acyl-F) showed the α-fiuorinated analogs to be as active as the pheromone components (threshold=0.1 μg), while the acyl fluorinated analogs had a 10-100 x higher threshold (=1-10 μg). Single-neuron recordings showed that IV neurons and II neurons (Dickens, 1990) responded to IV-α-F and III-α-F, respectively, while IV-acyl-F and III-acyl-F were inactive. Since a previous study showed compounds I, II, and IV to be essential for behavioral responses in the field, it seems likely that the activity of the α-fluorinated analogs observed here is due to the stimulation of IV neurons by IV-α-F as indicated in single neuron recordings.
13. Attraction of Chrysoperla carnea complex and Chrysopa spp. lacewings (Neuroptera: Chrysopidae) to aphid sex pheromone components and a synthetic blend of floral compounds in Hungary.
Science.gov (United States)
Koczor, Sándor; Szentkirályi, Ferenc; Birkett, Michael A; Pickett, John A; Voigt, Erzsébet; Tóth, Miklós
2010-12-01
The deployment of synthetic attractants for the manipulation of lacewing populations as aphid predators is currently used in integrated pest management. This study investigates a synthetic bait comprising floral compounds previously found to attract the Chrysoperla carnea complex, and, for the first time, the aphid sex pheromone components (1R,4aS,7S,7aR)-nepetalactol and (4aS,7S,7aR)-nepetalactone, in field experiments in Hungary, for their ability to manipulate lacewing populations. The synthetic floral bait attracted both sexes of the Chrysoperla carnea complex, and Chrysopa formosa Brauer showed minimal attraction. The aphid sex pheromone compounds alone attracted males of C. formosa and C. pallens (Rambur). When the two baits were combined, Chrysopa catches were similar to those with aphid sex pheromone baits alone, but carnea complex catches decreased significantly (by 85-88%). As the floral bait alone attracted both sexes of the carnea complex, it showed potential to manipulate the location of larval density via altering the site of oviposition. Aphid sex pheromone compounds alone attracted predatory males of Chrysopa spp. and can potentially be used to enhance biological control of aphids. For the carnea complex, however, a combination of both baits is not advantageous because of the decrease in adults attracted. Assumptions of intraguild avoidance underlying this phenomenon are discussed. Copyright © 2010 Society of Chemical Industry.
14. Structure elucidation and chemical synthesis of stigmolone, a novel type of prokaryotic pheromone.
Science.gov (United States)
Hull, W E; Berkessel, A; Plaga, W
1998-09-15
Approximately 2 micromol of a novel prokaryotic pheromone, involved in starvation-induced aggregation and formation of fruiting bodies by the myxobacterium Stigmatella aurantiaca, were isolated by a large-scale elution procedure. The pheromone was purified by HPLC, and high-resolution MS, IR, 1H-NMR, and 13C-NMR were used to identify the active substance as the hydroxy ketone 2,5, 8-trimethyl-8-hydroxy-nonan-4-one, which has been named stigmolone. The analysis was complicated by a solvent-dependent equilibrium between stigmolone and the cyclic enol-ether 3,4-dihydro-2,2, 5-trimethyl-6-(2-methylpropyl)-2H-pyran formed by intramolecular nucleophilic attack of the 8-OH group at the ketone C4 followed by loss of H2O. Both compounds were synthesized chemically, and their structures were confirmed by NMR analysis. Natural and synthetic stigmolone have the same biological activity at ca. 1 nM concentration.
15. Identification of Sex Pheromones and Sex Pheromone Mimics for Two North American Click Beetle Species (Coleoptera: Elateridae) in the Genus Cardiophorus Esch.
Science.gov (United States)
Serrano, Jacqueline M; Collignon, R Maxwell; Zou, Yunfan; Millar, Jocelyn G
2018-04-01
To date, all known or suspected pheromones of click beetles (Coleoptera: Elateridae) have been identified solely from species native to Europe and Asia; reports of identifications from North American species dating from the 1970s have since proven to be incorrect. While conducting bioassays of pheromones of a longhorned beetle (Coleoptera: Cerambycidae), we serendipitously discovered that males of Cardiophorus tenebrosus L. and Cardiophorus edwardsi Horn were specifically attracted to the cerambycid pheromone fuscumol acetate, (E)-6,10-dimethylundeca-5,9-dien-2-yl acetate, suggesting that this compound might also be a sex pheromone for the two Cardiophorus species. Further field bioassays and electrophysiological assays with the enantiomers of fuscumol acetate determined that males were specifically attracted by the (R)-enantiomer. However, subsequent analyses of extracts of volatiles from female C. tenebrosus and C. edwardsi showed that the females actually produced a different compound, which was identified as (3R,6E)-3,7,11-trimethyl-6,10-dodecadienoic acid methyl ester (methyl (3R,6E)-2,3-dihydrofarnesoate). In field trials, both the racemate and the (R)-enantiomer of the pheromone attracted similar numbers of male beetles, suggesting that the (S)-enantiomer was not interfering with responses to the insect-produced (R)-enantiomer. This report constitutes the first conclusive identification of sex pheromones for any North American click beetle species. Possible reasons for the strong and specific attraction of males to fuscumol acetate, which is markedly different in structure to the actual pheromone, are discussed.
16. Effects of two pheromone trap densities against banana weevil Cosmopolites sordidus, populations and their impact on plant damage in Uganda
NARCIS (Netherlands)
Tinzaara, W.; Gold, C.S.; Kagezi, G.H.; Dicke, M.; Huis, van A.; Nankinga, C.; Tushemereirwe, W.; Ragama, P.E.
2005-01-01
An on-farm study to evaluate the effect of pheromone trap density on the population of the banana weevil, Cosmopolites sordidus (Germar) (Col., Curculionidae) was conducted in Masaka district, Uganda. The pheromone used was Cosmolure+, a commercially available weevil aggregation pheromone. Forty-two
17. Analysis of the Agrotis segetum pheromone gland transcriptome in the light of sex pheromone biosynthesis.
Science.gov (United States)
Ding, Bao-Jian; Löfstedt, Christer
2015-09-18
Moths rely heavily on pheromone communication for mate finding. The pheromone components of most moths are modified from the products of normal fatty acid metabolism by a set of tissue-specific enzymes. The turnip moth, Agrotis segetum uses a series of homologous fatty-alcohol acetate esters ((Z)-5-decenyl, (Z)-7-dodecenyl, and (Z)-9 tetradecenyl acetate) as its sex pheromone components. The ratio of the components differs between populations, making this species an interesting subject for studies of the enzymes involved in the biosynthetic pathway and their influence on sex pheromone variation. Illumina sequencing and comparative analysis of the transcriptomes of the pheromone gland and abdominal epidermal tissue, enabled us to identify genes coding for putative key enzymes involved in the pheromone biosynthetic pathway, such as fatty acid synthase, β-oxidation enzymes, fatty-acyl desaturases (FAD), fatty-acyl reductases (FAR), and acetyltransferases. We functionally assayed the previously identified ∆11-desaturase [GenBank: ES583599, JX679209] and FAR [GenBank: JX679210] and candidate acetyltransferases (34 genes) by heterologous expression in yeast. The functional assay confirmed that the ∆11-desaturase interacts with palmitate and produces (Z)-11-hexadecenoate, which is the common unsaturated precursor of three homologous pheromone component acetates produced by subsequent chain-shortening, reduction and acetylation. Much lower, but still visible, activity on 14C and 12C saturated acids may account for minor pheromone compounds previously observed in the pheromone gland. The FAR characterized can operate on various unsaturated fatty acids that are the immediate acyl precursors of the different A. segetum pheromone components. None of the putative acetyltransferases that we expressed heterologously did acetylate any of the fatty alcohols tested as substrates. The massive sequencing technology generates enormous amounts of candidate genes potentially
18. Receptor chirality and behavioral specificity of the boll weevil,Anthonomus grandis Boh. (Coleoptera: Curculionidae), for its pheromone, (+)-grandisol.
Science.gov (United States)
Dickens, J C; Mori, K
1989-02-01
Electrophysiological recordings from antennal olfactory receptors and field behavioral experiments showed both male and female boll weevils,Anthonomus grandis Boh. (Coleoptera: Curculionidae), to respond specifically to (+)-grandisol, an enantiomer of compound I of the boll weevil aggregation pheromone. Single-cell recordings revealed antennal olfactory neurons in both male and female weevils keyed to (+)-grandisol. Electroantennograms in response to serial dilutions of the grandisol enaniiomers showed a threshold 100 to 1000 times lower for (+)-grandisol relative to its antipode. In field behavioral experiments, both sexes were significantly more attracted to (+)-grandisol in combination with the three other pheromone components than the combination with (-)-grandisol. When (-)-grandisol was placed with the (+)-enantiomer at equal dosages, a slight although statistically insignificant inhibition occurred. Subsequent field tests showed that the low level of attraction exhibited by (-)-grandisol in combination with the other three pheromone components could be attributed to the other three components alone. These results are in contrast with an earlier study, which found (-)-grandisol to be as attractive as the (+)-enantiomer.
19. Pheromonal Communication in the European House Dust Mite, Dermatophagoides pteronyssinus
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Johannes L.M. Steidle
2014-08-01
Full Text Available Despite the sanitary importance of the European house dust mite Dermatophagoides pteronyssinus (Trouessart, 1897, the pheromonal communication in this species has not been sufficiently studied. Headspace analysis using solid phase micro extraction (SPME revealed that nerol, neryl formate, pentadecane, (6Z,9Z-6,9-heptadecadiene, and (Z-8-heptadecene are released by both sexes whereas neryl propionate was released by males only. Tritonymphs did not produce any detectable volatiles. In olfactometer experiments, pentadecane and neryl propionate were attractive to both sexes as well as to tritonymphs. (Z-8-heptadecene was only attractive to male mites. Therefore it is discussed that pentadecane and neryl propionate are aggregation pheromones and (Z-8-heptadecene is a sexual pheromone of the European house dust mite D. pteronyssinus. To study the potential use of pheromones in dust mite control, long-range olfactometer experiments were conducted showing that mites can be attracted to neryl propionate over distances of at least 50 cm. This indicates that mite pheromones might be useable to monitor the presence or absence of mites in the context of control strategies.
20. Peptide pheromone signaling in Streptococcus and Enterococcus
Science.gov (United States)
Cook, Laura C.; Federle, Michael J.
2014-01-01
Intercellular chemical signaling in bacteria, commonly referred to as quorum sensing (QS), relies on the production and detection of compounds known as pheromones to elicit coordinated responses among members of a community. Pheromones produced by Gram-positive bacteria are comprised of small peptides. Based on both peptide structure and sensory system architectures, Gram-positive bacterial signaling pathways may be classified into one of four groups with a defining hallmark: cyclical peptides of the Agr type, peptides that contain Gly-Gly processing motifs, sensory systems of the RNPP family, or the recently characterized Rgg-like regulatory family. The recent discovery that Rgg family members respond to peptide pheromones increases substantially the number of species in which QS is likely a key regulatory component. These pathways control a variety of fundamental behaviors including conjugation, natural competence for transformation, biofilm development, and virulence factor regulation. Overlapping QS pathways found in multiple species and pathways that utilize conserved peptide pheromones provide opportunities for interspecies communication. Here we review pheromone signaling identified in the genera Enterococcus and Streptococcus, providing examples of all four types of pathways. PMID:24118108
1. Chemical communication in termites: syn-4,6-dimethylundecan-1-ol as trail-following pheromone, syn-4,6-dimethylundecanal and (5E)-2,6,10-trimethylundeca-5,9-dienal as the respective male and female sex pheromones in Hodotermopsis sjoestedti (Isoptera, Archotermopsidae).
Science.gov (United States)
Lacey, Michael J; Sémon, Etienne; Krasulová, Jana; Sillam-Dussès, David; Robert, Alain; Cornette, Richard; Hoskovec, Michal; Záček, Petr; Valterová, Irena; Bordereau, Christian
2011-12-01
The trail-following pheromone and sex pheromones were investigated in the Indomalayan termite Hodotermopsis sjoestedti belonging to the new family Archotermopsidae. Gas chromatography coupled to mass spectrometry (GC-MS) after solid phase microextraction (SPME) of the sternal gland secretion of pseudergates and trail-following bioassays demonstrated that the trail-following pheromone of H. sjoestedti was syn-4,6-dimethylundecan-1-ol, a new chemical structure for termite pheromones. GC-MS after SPME of the sternal gland secretion of alates also allowed the identification of sex-specific compounds. In female alates, the major sex-specific compound was identified as (5E)-2,6,10-trimethylundeca-5,9-dienal, a compound previously identified as the female sex pheromone of the termite Zootermopsis nevadensis. In male alates, the major sex-specific compound was identified as syn-4,6-dimethylundecanal, a homolog of syn-4,6-dimethyldodecanal, which has previously been confirmed as the male sex pheromone of Z. nevadensis. The presence of sex-specific compounds in alates of H. sjoestedti strongly suggests for this termite the presence of sex-specific pairing pheromones which were only known until now in Z. nevadensis. Our results showed therefore a close chemical relationship between the pheromones of the taxa Hodotermopsis and Zootermopsis and, in contrast, a clear difference with the taxa Stolotermes and Porotermes, which is in total agreement with the recent creation of the families Archotermopsidae and Stolotermitidae as a substitute for the former family Termopsidae. Copyright © 2011 Elsevier Ltd. All rights reserved.
2. Pheromone Binding Protein EhipPBP1 Is Highly Enriched in the Male Antennae of the Seabuckthorn Carpenterworm and Is Binding to Sex Pheromone Components
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Ping Hu
2018-04-01
Full Text Available The seabuckthorn carpenterworm moth Eogystia hippophaecolus is a major threat to seabuckthorn plantations, causing considerable ecological and economic losses in China. Transcriptomic analysis of E. hippophaecolus previously identified 137 olfactory proteins, including three pheromone-binding proteins (PBPs. We investigated the function of E. hippophaecolus PBP1 by studying its mRNA and protein expression profiles and its binding ability with different compounds. The highest levels of expression were in the antennae, particularly in males, with much lower levels of expression in the legs and external genitals. Recombinant PBP1 showed strong binding to sex-pheromone components, suggesting that antennal EhipPBP1 is involved in binding sex-pheromone components during pheromone communication.
3. Pheromone Signalling
Science.gov (United States)
2011-01-01
Pheromones are chemicals used to communicate with members of the same species. First described in insects, pheromones are often used to attract mates but in social insects, such as ants and bees, pheromone use is much more sophisticated. For example, ants use pheromones to make foraging trails and the chemical and physical properties of the…
4. Optimization of Pheromone Traps for Coryphodema tristis (Lepidoptera: Cossidae).
Science.gov (United States)
Bouwer, Marc Clement; Slippers, Bernard; Wingfield, Michael John; Allison, Jeremy Dean; Rohwer, Egmont Richard
2017-08-01
The Coryphodema tristis (Drury) is an important pest of Eucalyptus nitens (Deane and Maiden) plantations in South Africa. The gregarious larvae of this pest cause damage by feeding on the tree sapwood, and adults emerge in spring each year. The aim of this study was to optimize pheromone traps for operational use in management programs. This was achieved by investigating different pheromone blend combinations and trap types for efficacy under field conditions. Our results confirm that the cross vane bucket funnel trap baited with a 95:2.5:2.5 volumetric blend of Z9-14:OAc, Z9-14:OH, and 14Ac was superior to similarly baited standard bucket funnel and delta traps. We also estimated the release rate and ratios of the pheromone compounds loaded into an artificial permeation dispenser through solid-phase microextraction sampling. Results showed that the released blend of pheromone compounds mirrored the dispensed ratios relatively accurately and that release rates are affected by temperature. © The Authors 2017. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For Permissions, please email: journals.permissions@oup.com.
5. Intra-annual variation in responses by flying southern pine beetles (Coleoptera: Curculionidae: Scolytinae) to pheromone component endo-brevicomin
Science.gov (United States)
Brian T. Sullivan; Cavell Brownie; JoAnne P. Barrett
2016-01-01
The southern pine beetle Dendroctonus frontalis Zimmermann (Coleoptera: Curculionidae: Scolytinae) is attracted to an aggregation pheromone that includes the multifunctional pheromone component endobrevicomin. The effect of endo-brevicomin on attractive lures varies from strong enhancement to reduction of beetle attraction depending upon release rate, lure component...
6. Characterization of an Aggregation Pheromone in Hylesinus pruinosus (Coleoptera: Curculionidae: Scolytinae)
Science.gov (United States)
William Shepherd; Brian Sullivan; Bradley Hoosier; JoAnne Barrett; Tessa Bauman
2010-01-01
We conducted laboratory and field bioassays to characterize the pheromone system of an ash bark beetle, Hylesinus pruinosus Eichhoff (Coleoptera: Curculionidae: Scolytinae). Solitary females in newly initiated galleries in ash logs produced (+)-exo-brevicomin, whereas male beetles paired with females produced (+)-endo-brevicomin, lesser quantities of...
7. Synthetic sex pheromone attracts the leishmaniasis vector Lutzomyia longipalpis (Diptera: Psychodidae) to traps in the field.
Science.gov (United States)
Bray, D P; Bandi, K K; Brazil, R P; Oliveira, A G; Hamilton, J G C
2009-05-01
Improving vector control remains a key goal in reducing the world's burden of infectious diseases. More cost-effective approaches to vector control are urgently needed, particularly because vaccines are unavailable and treatment is prohibitively expensive. The causative agent of American visceral leishmaniasis (AVL), Leishmania chagasi, Cunha and Chagas (Kinetoplastida: Trypanosomatidae), is transmitted between animal and human hosts by blood-feeding female sand flies attracted to mating aggregations formed on or above host animals by male-produced sex pheromones. Our results show the potential of using synthetic pheromones to control populations of Lutzomyia longipalpis Lutz and Neiva (Diptera: Psychodidae), the sand fly vector of one of the world's most important neglected diseases, AVL. We showed that a synthetic pheromone, (+/-)-9-methylgermacrene-B, produced from a low-cost plant intermediate, attracted females in the laboratory. By formulating dispensers that released this pheromone at a rate similar to that released by aggregating males, we were able to attract flies of both sexes to traps in the field. These dispensers worked equally well when deployed with mechanical light traps and inexpensive sticky traps. If deployed effectively, pheromone-based traps could be used to decrease AVL transmission rates through specific targeting and reduction of L. longipalpis populations. This is the first study to show attraction of a human disease-transmitting insect to a synthetic pheromone in the field, showing the general applicability of this novel approach for developing new tools for use in vector control.
8. Synthetic Sex Pheromone Attracts the Leishmaniasis Vector Lutzomyia longipalpis (Diptera: Psychodidae) to Traps in the Field
Science.gov (United States)
Bray, D. P.; Bandi, K. K.; Brazil, R. P.; Oliveira, A. G.; Hamilton, J.G.C.
2011-01-01
Improving vector control remains a key goal in reducing the world’s burden of infectious diseases. More cost-effective approaches to vector control are urgently needed, particularly as vaccines are unavailable and treatment is prohibitively expensive. The causative agent of AVL, Leishmania chagasi, Cunha and Chagas (Kinetoplastida: Trypanosomatidae) is transmitted between animal and human hosts by blood-feeding female sand flies, attracted to mating aggregations formed on or above host animals by male-produced sex pheromones. Our results demonstrate the potential of using synthetic pheromones to control populations of Lutzomyia longipalpis Lutz and Neiva (Diptera: Psychodidae), the sand fly vector of one of the world’s most important neglected diseases, American visceral leishmaniasis (AVL). We showed that a synthetic pheromone, (±)-9-methylgermacrene-B, produced from a low-cost plant intermediate, attracted females in the laboratory. Then by formulating dispensers that released this pheromone at a rate similar to that released by aggregating males, we were able to attract flies of both sexes to traps in the field. These dispensers worked equally well when deployed with mechanical light traps and inexpensive sticky traps. If deployed effectively, pheromone-based traps could be used to decrease AVL transmission rates through specific targeting and reduction of L. longipalpis populations. This is the first study to show attraction of a human disease-transmitting insect to a synthetic pheromone in the field, demonstrating the general applicability of this novel approach for developing new tools for use in vector control. PMID:19496409
9. Moth sex pheromone receptors and deceitful parapheromones.
Directory of Open Access Journals (Sweden)
Pingxi Xu
Full Text Available The insect's olfactory system is so selective that male moths, for example, can discriminate female-produced sex pheromones from compounds with minimal structural modifications. Yet, there is an exception for this "lock-and-key" tight selectivity. Formate analogs can be used as replacement for less chemically stable, long-chain aldehyde pheromones, because male moths respond physiologically and behaviorally to these parapheromones. However, it remained hitherto unknown how formate analogs interact with aldehyde-sensitive odorant receptors (ORs. Neuronal responses to semiochemicals were investigated with single sensillum recordings. Odorant receptors (ORs were cloned using degenerate primers, and tested with the Xenopus oocyte expression system. Quality, relative quantity, and purity of samples were evaluated by gas chromatography and gas chromatography-mass spectrometry. We identified olfactory receptor neurons (ORNs housed in trichoid sensilla on the antennae of male navel orangeworm that responded equally to the main constituent of the sex pheromone, (11Z,13Z-hexadecadienal (Z11Z13-16Ald, and its formate analog, (9Z,11Z-tetradecen-1-yl formate (Z9Z11-14OFor. We cloned an odorant receptor co-receptor (Orco and aldehyde-sensitive ORs from the navel orangeworm, one of which (AtraOR1 was expressed specifically in male antennae. AtraOR1•AtraOrco-expressing oocytes responded mainly to Z11Z13-16Ald, with moderate sensitivity to another component of the sex pheromone, (11Z,13Z-hexadecadien-1-ol. Surprisingly, this receptor was more sensitive to the related formate than to the natural sex pheromone. A pheromone receptor from Heliothis virescens, HR13 ( = HvirOR13 showed a similar profile, with stronger responses elicited by a formate analog than to the natural sex pheromone, (11Z-hexadecenal thus suggesting this might be a common feature of moth pheromone receptors.
10. Sex Pheromone of the Cotton Mealybug, Phenacoccus solenopsis, with an Unusual Cyclobutane Structure.
Science.gov (United States)
Tabata, Jun; Ichiki, Ryoko T
2016-11-01
The cotton mealybug, Phenacoccus solenopsis, the distribution of which was formerly limited to Nearctic and Neotropical regions, recently invaded many countries in various regions including Asia, Africa, and the Pacific. More recently, P. solenopsis was newly recorded in Japan and is currently an emerging pest of agricultural crops. In this study, we determined the structure of a sex pheromone of P. solenopsis in order to develop an effective lure for monitoring this pest. From volatiles emitted by virgin adult females, we isolated a compound attractive to males. By means of coupled gas chromatography-mass spectrometry and nuclear magnetic resonance spectroscopy, we identified this as (2,2-dimethyl-3-isopropylidenecyclobutyl)methyl 3-methylbut-2-enoate. This compound was synthesized and shown to be attractive to male P. solenopsis. Analysis by gas chromatography using an enantioselective stationary phase and polarimetry analyses of the natural pheromone and synthetic enantiomers showed the natural compound to be the (R)-(-)-enantiomer. This compound is an ester of maconelliol, which has an unusual cyclobutane structure found in sex pheromones of other mealybug species, and senecioic acid, also found in the pheromones of other mealybug species. However, this is the first example of the ester of maconelliol and senecioic acid as a natural product.
11. Male sex pheromone components in Heliconius butterflies released by the androconia affect female choice
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Kathy Darragh
2017-11-01
Full Text Available Sex-specific pheromones are known to play an important role in butterfly courtship, and may influence both individual reproductive success and reproductive isolation between species. Extensive ecological, behavioural and genetic studies of Heliconius butterflies have made a substantial contribution to our understanding of speciation. Male pheromones, although long suspected to play an important role, have received relatively little attention in this genus. Here, we combine morphological, chemical and behavioural analyses of male pheromones in the Neotropical butterfly Heliconius melpomene. First, we identify putative androconia that are specialized brush-like scales that lie within the shiny grey region of the male hindwing. We then describe putative male sex pheromone compounds, which are largely confined to the androconial region of the hindwing of mature males, but are absent in immature males and females. Finally, behavioural choice experiments reveal that females of H. melpomene, H. erato and H. timareta strongly discriminate against conspecific males which have their androconial region experimentally blocked. As well as demonstrating the importance of chemical signalling for female mate choice in Heliconius butterflies, the results describe structures involved in release of the pheromone and a list of potential male sex pheromone compounds.
12. Isolation of a pyrazine alarm pheromone component from the fire ant, Solenopsis invicta.
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Vander Meer, Robert K; Preston, Catherine A; Choi, Man-Yeon
2010-02-01
Alarm pheromones in social insects are an essential part of a complex of pheromone interactions that contribute to the maintenance of colony integrity and sociality. The alarm pheromones of ants were among the first examples of animal pheromones identified, primarily because of the large amount of chemical produced and the distinctive responses of ants to the pheromone. However, the alarm pheromone of the fire ant, Solenopsis invicta, eluded identification for over four decades. We identified 2-ethyl-3,6-dimethylpyrazine as an alarm pheromone component of S. invicta. Worker fire ants detect the pyrazine alarm pheromone at 30 pg/ml, which is comparable to alarm pheromone sensitivities reported for other ant species. The source of this alarm pheromone are the mandibular glands, which, in fire ants, are not well developed and contain only about 300 pg of the compound, much less than the microgram quantities of alarm pheromones reported for several other ant species. Female and male sexuals and workers produce the pyrazine, which suggests that it may be involved in fire ant mating flight initiation, as well as the typical worker alarm response. This is the first report of 2-ethyl-3,6-dimethylpyrazine from a Solenopsis species and the first example of this alkaloid functioning as an alarm pheromone.
13. Selective breeding for increased pheromone production in the boll weevil (Coleoptera: Curculionidae)
International Nuclear Information System (INIS)
McCoy, J.R.; Wright, J.E.
1990-01-01
The male boll weevil, Anthonomus grandis grandis Boheman, uses an aggregating pheromone to attract females, after which mating often occurs. Sterile boll weevil release programs depend upon this phenomenon to produce sterile matings with feral females. In an effort to increase the effectiveness of the individual sterile male and thereby reduce the number of sterile males required per hectare, a selective-breeding system was used to increase the total pheromone produced by individual male boll weevils. This breeding program increased the total pheromone production by individual male boll weevils to 4.5 times that of the parent population. After irradiation-induced sterilization, there remained 2.2 times more pheromone produced by the selected strain. Therefore, these sterile weevils should be about 2.2 times more attractive to feral females than the parent weevils now in use, and they have the potential to reduce the number of sterile males required in a sterile release program
14. Pheromone Production by an Invasive Bark Beetle Varies with Monoterpene Composition of its Naïve Host.
Science.gov (United States)
Taft, Spencer; Najar, Ahmed; Erbilgin, Nadir
2015-06-01
The secondary chemistry of host plants can have cascading impacts on the establishment of new insect herbivore populations, their long-term population dynamics, and their invasion potential in novel habitats. Mountain pine beetle, Dendroctonus ponderosae Hopkins (Coleoptera: Curculionidae) has recently expanded its range into forests of jack pine, Pinus banksiana Lamb., in western Canada. We investigated whether variations in jack pine monoterpenes affect beetle pheromone production, as the primary components of the beetle's aggregation pheromone, (-)-trans-verbenol and anti-aggregation pheromone (-)-verbenone, are biosynthesized from the host monoterpene α-pinene. Jack pine bolts were collected from five Canadian provinces east of the beetle's current range, live D. ponderosae were introduced into them, and their monoterpene compositions were characterized. Production of (-)-trans-verbenol and (-)-verbenone emitted by beetles was measured to determine whether pheromone production varies with monoterpene composition of jack pines. Depending on particular ratios of major monoterpenes in host phloem, jack pine could be classified into three monoterpenoid groups characterized by high amounts of (+)-α-pinene, 3-carene, or a more moderate blend of monoterpenes, and beetle pheromone production varied among these groups. Specifically, beetles reared in trees characterized by high (+)-α-pinene produced the most (-)-trans-verbenol and (-)-verbenone, while beetles in trees characterized by high 3-carene produced the least. Our results indicate that pheromone production by D. ponderosae will remain a significant aspect and important predictor of its survival and persistence in the boreal forest.
15. A protecting group-free synthesis of the Colorado potato beetle pheromone
NARCIS (Netherlands)
Wu, Zhongtao; Buter, Jeffrey; Minnaard, Adriaan J.; Jäger, Manuel; Dickschat, J.S.
2013-01-01
A novel synthesis of the aggregation pheromone of the Colorado potato beetle, Leptinotarsa decemlineata, has been developed based on a Sharpless asymmetric epoxidation in combination with a chemoselective alcohol oxidation using catalytic [(neocuproine)PdOAc](2)OTf2. Employing this approach, the
16. Blends of Pheromones, With and Without Host Plant Volatiles, Can Attract Multiple Species of Cerambycid Beetles Simultaneously
Science.gov (United States)
L.M. Hanks; J.A. Mongold-Diers; T.H. Atkinson; M.K. Fierke; M.D. Ginzel; E.E. Graham; T.M. Poland; A.B. Richards; M.L. Richardson; J.G. Millar
2018-01-01
Pheromone components of cerambycid beetles are often conserved, with a given compound serving as a pheromone component for multiple related species, including species native to different continents. Consequently, a single synthesized compound may attract multiple species to a trap simultaneously. Furthermore, our previous research in east-central Illinois had...
17. Unexpected plant odor responses in a moth pheromone system
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Angéla eRouyar
2015-05-01
Full Text Available Male moths rely on olfactory cues to find females for reproduction. Males also use volatile plant compounds (VPCs to find food sources and might use host-plant odor cues to identify the habitat of calling females. Both the sex pheromone released by conspecific females and VPCs trigger well-described oriented flight behavior towards the odor source. Whereas detection and central processing of pheromones and VPCs have been thought for a long time to be highly separated from each other, recent studies have shown that interactions of both types of odors occur already early at the periphery of the olfactory pathway. Here we show that detection and early processing of VPCs and pheromone can overlap between the two sub-systems. Using complementary approaches, i.e. single-sensillum recording of olfactory receptor neurons, in vivo calcium imaging in the antennal lobe, intracellular recordings of neurons in the macroglomerular complex (MGC and flight tracking in a wind tunnel, we show that some plant odorants alone, such as heptanal, activate the pheromone-specific pathway in male Agrotis ipsilon at peripheral and central levels. To our knowledge, this is the first report of a plant odorant with no chemical similarity to the molecular structure of the pheromone, acting as a partial agonist of a moth sex pheromone.
18. Chemical similarity between historical and novel host plants promotes range and host expansion of the mountain pine beetle in a naïve host ecosystem.
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Erbilgin, Nadir; Ma, Cary; Whitehouse, Caroline; Shan, Bin; Najar, Ahmed; Evenden, Maya
2014-02-01
Host plant secondary chemistry can have cascading impacts on host and range expansion of herbivorous insect populations. We investigated the role of host secondary compounds on pheromone production by the mountain pine beetle (Dendroctonus ponderosae) (MPB) and beetle attraction in response to a historical (lodgepole pine, Pinus contorta var. latifolia) and a novel (jack pine, Pinus banksiana) hosts, as pheromones regulate the host colonization process. Beetles emit the same pheromones from both hosts, but more trans-verbenol, the primary aggregation pheromone, was emitted by female beetles on the novel host. The phloem of the novel host contains more α-pinene, a secondary compound that is the precursor for trans-verbenol production in beetle, than the historical host. Beetle-induced emission of 3-carene, another secondary compound found in both hosts, was also higher from the novel host. Field tests showed that the addition of 3-carene to the pheromone mixture mimicking the aggregation pheromones produced from the two host species increased beetle capture. We conclude that chemical similarity between historical and novel hosts has facilitated host expansion of MPB in jack pine forests through the exploitation of common host secondary compounds for pheromone production and aggregation on the hosts. Furthermore, broods emerging from the novel host were larger in terms of body size. © 2013 The Authors. New Phytologist © 2013 New Phytologist Trust.
19. Identifying Possible Pheromones of Cerambycid Beetles by Field Testing Known Pheromone Components in Four Widely Separated Regions of the United States.
Science.gov (United States)
Millar, Jocelyn G; Mitchell, Robert F; Mongold-Diers, Judith A; Zou, Yunfan; Bográn, Carlos E; Fierke, Melissa K; Ginzel, Matthew D; Johnson, Crawford W; Meeker, James R; Poland, Therese M; Ragenovich, Iral; Hanks, Lawrence M
2018-02-09
20. Identification of the sex pheromone of the tree infesting Cossid Moth Coryphodema tristis (Lepidoptera: Cossidae.
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Marc Clement Bouwer
1. Identification of the sex pheromone of the tree infesting Cossid Moth Coryphodema tristis (Lepidoptera: Cossidae).
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Bouwer, Marc Clement; Slippers, Bernard; Degefu, Dawit; Wingfield, Michael John; Lawson, Simon; Rohwer, Egmont Richard
2015-01-01
2. Functional specificity of sex pheromone receptors in the cotton bollworm Helicoverpa armigera.
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Yang Liu
Full Text Available Male moths can accurately perceive the sex pheromone emitted from conspecific females by their highly accurate and specific olfactory sensory system. Pheromone receptors are of special importance in moth pheromone reception because of their central role in chemosensory signal transduction processes that occur in olfactory receptor neurons in the male antennae. There are a number of pheromone receptor genes have been cloned, however, only a few have been functionally characterized. Here we cloned six full-length pheromone receptor genes from Helicoverpa armigera male antennae. Real-time PCR showing all genes exhibited male-biased expression in adult antennae. Functional analyses of the six pheromone receptor genes were then conducted in the heterologous expression system of Xenopus oocytes. HarmOR13 was found to be a specific receptor for the major sex pheromone component Z11-16:Ald. HarmOR6 was equally tuned to both of Z9-16: Ald and Z9-14: Ald. HarmOR16 was sensitively tuned to Z11-16: OH. HarmOR11, HarmOR14 and HarmOR15 failed to respond to the tested candidate pheromone compounds. Our experiments elucidated the functions of some pheromone receptor genes of H. armigera. These advances may provide remarkable evidence for intraspecific mating choice and speciation extension in moths at molecular level.
3. Degradation of pheromone and plant volatile components by a same odorant-degrading enzyme in the cotton leafworm, Spodoptera littoralis.
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Nicolas Durand
Full Text Available Odorant-Degrading Enzymes (ODEs are supposed to be involved in the signal inactivation step within the olfactory sensilla of insects by quickly removing odorant molecules from the vicinity of the olfactory receptors. Only three ODEs have been both identified at the molecular level and functionally characterized: two were specialized in the degradation of pheromone compounds and the last one was shown to degrade a plant odorant.Previous work has shown that the antennae of the cotton leafworm Spodoptera littoralis, a worldwide pest of agricultural crops, express numerous candidate ODEs. We focused on an esterase overexpressed in males antennae, namely SlCXE7. We studied its expression patterns and tested its catalytic properties towards three odorants, i.e. the two female sex pheromone components and a green leaf volatile emitted by host plants.SlCXE7 expression was concomitant during development with male responsiveness to odorants and during adult scotophase with the period of male most active sexual behaviour. Furthermore, SlCXE7 transcription could be induced by male exposure to the main pheromone component, suggesting a role of Pheromone-Degrading Enzyme. Interestingly, recombinant SlCXE7 was able to efficiently hydrolyze the pheromone compounds but also the plant volatile, with a higher affinity for the pheromone than for the plant compound. In male antennae, SlCXE7 expression was associated with both long and short sensilla, tuned to sex pheromones or plant odours, respectively. Our results thus suggested that a same ODE could have a dual function depending of it sensillar localisation. Within the pheromone-sensitive sensilla, SlCXE7 may play a role in pheromone signal termination and in reduction of odorant background noise, whereas it could be involved in plant odorant inactivation within the short sensilla.
4. Poison and alarm: the Asian hornet Vespa velutina uses sting venom volatiles as an alarm pheromone.
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Cheng, Ya-Nan; Wen, Ping; Dong, Shi-Hao; Tan, Ken; Nieh, James C
2017-02-15
In colonial organisms, alarm pheromones can provide a key fitness advantage by enhancing colony defence and warning of danger. Learning which species use alarm pheromone and the key compounds involved therefore enhances our understanding of how this important signal has evolved. However, our knowledge of alarm pheromones is more limited in the social wasps and hornets compared with the social bees and ants. Vespa velutina is an economically important and widespread hornet predator that attacks honey bees and humans. This species is native to Asia and has now invaded Europe. Despite growing interest in V. velutina , it was unknown whether it possessed an alarm pheromone. We show that these hornets use sting venom as an alarm pheromone. Sting venom volatiles were strongly attractive to hornet workers and triggered attacks. Two major venom fractions, consisting of monoketones and diketones, also elicited attack. We used gas chromatography coupled to electroantennographic detection (GC-EAD) to isolate 13 known and 3 unknown aliphatic ketones and alcohols in venom that elicited conspicuous hornet antennal activity. Two of the unknown compounds may be an undecen-2-one and an undecene-2,10-dinone. Three major compounds (heptan-2-one, nonan-2-one and undecan-2-one) triggered attacks, but only nonan-2-one did so at biologically relevant levels (10 hornet equivalents). Nonan-2-one thus deserves particular attention. However, the key alarm releasers for V. velutina remain to be identified. Such identification will help to illuminate the evolution and function of alarm compounds in hornets. © 2017. Published by The Company of Biologists Ltd.
5. Electrophysiological and olfactometer responses of two histerid predators to three pine bark beetle pheromones
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William P. Shepherd; Brian T. Sullivan; Richard A. Goyer; Kier D. Klepzig
2005-01-01
We measured electrophysiological responses in the antennae of two predaceous hister beetles, Platysoma parallelum and Plegaderus transversus, exposes to racemic mixtures of primary aggregation pheromones of scolytid bark beetle prey, ipsenol, ipsdienol, and frontalin. No significant differences were found for either histerid...
6. Nectar Attracts Foraging Honey Bees with Components of Their Queen Pheromones.
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Liu, Fanglin; Gao, Jie; Di, Nayan; Adler, Lynn S
2015-11-01
Floral nectar often contains chemicals that are deterrent to pollinators, presenting potential challenges to outcrossing plant species. Plants may be able to co-opt pollinator chemical signals to mitigate the negative effects of nectar deterrent compounds on pollination services. We found that buckwheat (Fagopyrum esculentum) and Mexican sunflower (Tithonia diversifolia) produce nectar with abundant phenolics, including three components of the Apis honeybee queen mandibular pheromone (QMP). In addition, these nectars contain a non-pheromonal phenolic, chlorogenic acid (CA), which was toxic to honeybees, and T. diversifolia nectar also contained isochlorogenic acid (IA). Fresh nectar or solutions containing nectar phenolics reduced Apis individual feeding compared to sucrose solutions. However, freely foraging bees preferred solutions with QMP components to control solutions, and QMP components over-rode or reversed avoidance of CA and IA. Furthermore, prior exposure to the presence or just the odor of QMP components removed the deterrent effects of CA and IA. By mimicking the honey bee pheromone blend, nectar may maintain pollinator attraction in spite of deterrent nectar compounds.
7. (R)-3-hydroxyhexan-2-one is a major pheromone component of Anelaphus inflaticollis (Coleoptera: Cerambycidae).
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Ray, A M; Swift, I P; Moreira, J A; Millar, J G; Hanks, L M
2009-10-01
We report the identification and field bioassays of a major component of the male-produced aggregation pheromone of Anelaphus inflaticollis Chemsak, an uncommon desert cerambycine beetle. Male A. inflaticollis produced a sex-specific blend of components that included (R)-3-hydroxyhexan-2-one, (S)-2-hydroxyhexan-3-one, 2,3-hexanedione, and (2R,3R)- and (2R,3S)-2,3-hexanediols. Field trials with baited bucket traps determined that the reconstructed synthetic pheromone blend and (R)-3-hydroxyhexan-2-one alone attracted adult A. inflaticollis of both sexes, with significantly more beetles being attracted to the blend. We conclude that (R)-3-hydroxyhexan-2-one is a major pheromone component of A. inflaticollis, and our results suggest that one or more of the minor components may further increase attraction of conspecifics. Scanning electron microscopy showed that male A. inflaticollis have pores on the prothorax that are consistent in structure with sex-specific pheromone gland pores in related species. Males also displayed stereotyped calling behavior similar to that observed in other cerambycine species. This study represents the first report of volatile pheromones for a cerambycine species in the tribe Elaphidiini.
8. HONEY BEE COLONY PHEROMONES
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M Dražić
2001-09-01
Full Text Available ABSTRACT Pheromones are chemicals produced as liquids by specialised cells or glands and transmitted into the environment as liquids or gases. In contrary to hormones, which are excreted in organism and have effect exclusively on organism that produced them, pheromones are excreted outside organism and effect on different individuals of the same species. Pheromones mediate nearly all aspects of honeybee colony life including social defence, brood care, mating, orientation, foraging and reproduction. Pheromone investigation has high economic importance. With use of pheromones it is possible to manipulate with pest insects on crops or to direct honeybees during pollination on target plants.
9. Attraction of stink bug (Hemiptera: Pentatomidae) nymphs to Euschistus aggregation pheromone in the field
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Phytophagous stink bugs (Hemiptera: Pentatomidae) are primary pests in most fruit, vegetable, grain, and row crops worldwide. Pheromones have been identified and synthesized for several species of economically important stink bug pests. When yellow pyramid traps are baited with lures containing thes...
10. Pheromone discrimination by a pH-tuned polymorphism of the Bombyx mori pheromone-binding protein
OpenAIRE
Damberger, Fred F.; Michel, Erich; Ishida, Yuko; Leal, Walter S.; Wüthrich, Kurt
2013-01-01
Pheromone recognition by insect olfactory organs is critical for the ability of insects to locate mates. The silkworm moth Bombyx mori has long served as a model organism for studies of this process. Key components in the sensory organs have been identified, including the pheromone bombykol, pheromone-binding protein (BmorPBP), ligand-degrading enzymes, and the pheromone receptor, but many details of the mechanism allowing highly sensitive and selective pheromone detection are still elusive. ...
11. Alarm Pheromone Activity of Nymph-specific Geraniol in Chrysanthemum Lace Bug Corythucha marmorata against Adults and Nymphs.
Science.gov (United States)
Watanabe, Kisaki; Shimizu, Nobuhiro
2015-09-01
The exotic insect pest Corythucha marmorata (Uhler) is increasingly spreading in Japan using the weed Solidago canadensis L. as a major host plant. The nymphs form colonies on the backs of leaves where they crowd together; however, aggregation does not occur in the adults. When an individual nymph is crushed using a needle tip and further the needle tip covered with the nymph's bodily fluids is moved slowly toward the center of the crowd, the surrounding nymphs display an escape behavior and their aggregation is disrupted. We detected geraniol as a nymph-specific volatile component. Bioassay results indicated that geraniol was effective as an alarm pheromone on second to fifth instar nymphs. Furthermore, we found that male and female adults responded sensitively to the alarm pheromone produced by nymphs. These results suggest that although the adult insects do not secrete geraniol, they can detect it produced by nymphs, thereby retaining the ability to escape from danger while suppressing the cost of geraniol production. The present study is the first to demonstrate that an alarm pheromone secreted by nymphs is also effective in adults among Tingidae.
12. Novel direct factor Xa inhibitory compounds from Tenebrio molitor with anti-platelet aggregation activity.
Science.gov (United States)
Lee, Wonhwa; Kim, Mi-Ae; Park, InWha; Hwang, Jae Sam; Na, MinKyun; Bae, Jong-Sup
2017-11-01
Tenebrio molitor is an edible insect that has antimicrobial, anticancer, and antihypertensive effects. The aim of this study was to identify the unreported bioactive compounds from T. molitor larvae with inhibitory activities against factor Xa (FXa) and platelet aggregation. Isolated compounds were evaluated for their anti-FXa and anti-platelet aggregation properties by monitoring clotting time, platelet aggregation, FXa activity, and thrombus formation. A diketopiperazine (1, cyclo( L -Pro- L -Tyr)) and a phenylethanoid (2, N-acetyltyramine) were isolated and inhibited the catalytic activity of FXa in a mixed inhibition model and inhibited platelet aggregation induced by adenosine diphosphate (ADP) and U46619. They inhibited ADP- and U46619-induced phosphorylation of myristoylated alanine-rich C kinase substrate (MARCKS) and the expression of P-selectin and PAC-1 in platelets. They also improved the production of nitric oxide and inhibited the oversecretion of endothelin-1 compared to that of the ADP- or U46619-treated group. In an animal model of arterial and pulmonary thrombosis, the isolated compounds showed enhanced antithrombotic effects. They also elicited anticoagulant effects in mice. Compounds 1-2 inhibited ADP-, collagen-, or U46619-induced platelet aggregation and showed similar anti-thrombotic efficacy to rivaroxaban, a positive control. Therefore, 1-2 could serve as candidates and provide scaffolds for the development of new anti-FXa and anti-platelet drugs. Copyright © 2017 Elsevier Ltd. All rights reserved.
13. Effects of sex pheromones and sexual maturation on locomotor activity in female sea lamprey (Petromyzon marinus)
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Walaszczyk, Erin J.; Johnson, Nicholas S.; Steibel, Juan Pedro; Li, Weiming
2013-01-01
Synchronization of male and female locomotor rhythmicity can play a vital role in ensuring reproductive success. Several physiological and environmental factors alter these locomotor rhythms. As sea lamprey, Petromyzon marinus, progress through their life cycle, their locomotor activity rhythm changes multiple times. The goal of this study was to elucidate the activity patterns of adult female sea lamprey during the sexual maturation process and discern the interactions of these patterns with exposure to male pheromones. During these stages, preovulated and ovulated adult females are exposed to sex pheromone compounds, which are released by spermiated males and attract ovulated females to the nest for spawning. The locomotor behavior of adult females was monitored in a natural stream with a passive integrated tag responder system as they matured, and they were exposed to a sex pheromone treatment (spermiated male washings) or a control (prespermiated male washings). Results showed that, dependent on the hour of day, male sex pheromone compounds reduce total activity (p reproductive synchrony of mature adults, thus increasing reproductive success in this species.
14. Attraction of spathius agrili yang (Hymenoptera: eulophidae) to male-produced "aggregation-sex pheromone:" differences between the sexes and mating status
Science.gov (United States)
Male and female Spathius agrili Yang were tested for attraction to the synthetic male pheromone. Lures consisting of a 3-component pheromone blend were placed in the center of a white filter paper target used to activate upwind flight in the wind tunnel. When virgin males and females were tested for...
15. Sex Pheromone of the Almond Moth and the Indian Meal Moth: cis-9, trans-12-Tetradecadienyl Acetate.
Science.gov (United States)
Kuwahara, Y; Kitamura, C; Takashi, S; Hara, H; Ishii, S; Fukami, H
1971-02-26
Female moths of different species but belonging to the same subfamily produce an identical compound as their sex pheromone. The sex pheromone of the almond moth, Cadra cautella (Walker), and the Indian meal moth, Plodia interpunctella (Hübner), has been isolated and identified as cis-9, trans-12-tetradecadienyl acetate.
16. It's All in the Mix: Blend-Specific Behavioral Response to a Sexual Pheromone in a Butterfly
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Larsdotter-Mellström, Helena; Eriksson, Kerstin; Liblikas I, Ilme; Wiklund, Christer; Borg-Karlson, Anna K.; Nylin, Sören; Janz, Niklas; Carlsson, Mikael A.
2016-01-01
Among insects, sexual pheromones are typically mixtures of two to several components, all of which are generally required to elicit a behavioral response. Here we show for the first time that a complete blend of sexual pheromone components is needed to elicit a response also in a butterfly. Males of the Green-veined White, Pieris napi, emit an aphrodisiac pheromone, citral, from wing glands. This pheromone is requisite for females to accept mating with a courting male. Citral is a mixture of the two geometric isomers geranial (E-isomer) and neral (Z-isomer) in an approximate 1:1 ratio. We found that both these compounds are required to elicit acceptance behavior, which indicates synergistic interaction between processing of the isomers. Using functional Ca2+ imaging we found that geranial and neral evoke significantly different but overlapping glomerular activity patterns in the antennal lobe, which suggests receptors with different affinity for the two isomers. However, these glomeruli were intermingled with glomeruli responding to, for example, plant-related compounds, i.e., no distinct subpopulation of pheromone-responding glomeruli as in moths and other insects. In addition, these glomeruli showed lower specificity than pheromone-activated glomeruli in moths. We could, however, not detect any mixture interactions among four identified glomeruli, indicating that the synergistic effect may be generated at a higher processing level. Furthermore, correlations between glomerular activity patterns evoked by the single isomers and the blend did not change over time. PMID:26973536
17. The male sex pheromone of the butterfly Bicyclus anynana: towards an evolutionary analysis.
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Caroline M Nieberding
Full Text Available BACKGROUND: Female sex pheromones attracting mating partners over long distances are a major determinant of reproductive isolation and speciation in Lepidoptera. Males can also produce sex pheromones but their study, particularly in butterflies, has received little attention. A detailed comparison of sex pheromones in male butterflies with those of female moths would reveal patterns of conservation versus novelty in the associated behaviours, biosynthetic pathways, compounds, scent-releasing structures and receiving systems. Here we assess whether the African butterfly Bicyclus anynana, for which genetic, genomic, phylogenetic, ecological and ethological tools are available, represents a relevant model to contribute to such comparative studies. METHODOLOGY/PRINCIPAL FINDINGS: Using a multidisciplinary approach, we determined the chemical composition of the male sex pheromone (MSP in the African butterfly B. anynana, and demonstrated its behavioural activity. First, we identified three compounds forming the presumptive MSP, namely (Z-9-tetradecenol (Z9-14:OH, hexadecanal (16:Ald and 6,10,14-trimethylpentadecan-2-ol (6,10,14-trime-15-2-ol, and produced by the male secondary sexual structures, the androconia. Second, we described the male courtship sequence and found that males with artificially reduced amounts of MSP have a reduced mating success in semi-field conditions. Finally, we could restore the mating success of these males by perfuming them with the synthetic MSP. CONCLUSIONS/SIGNIFICANCE: This study provides one of the first integrative analyses of a MSP in butterflies. The toolkit it has developed will enable the investigation of the type of information about male quality that is conveyed by the MSP in intraspecific communication. Interestingly, the chemical structure of B. anynana MSP is similar to some sex pheromones of female moths making a direct comparison of pheromone biosynthesis between male butterflies and female moths relevant
18. Natural variation in dauer pheromone production and sensing supports intraspecific competition in nematodes.
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Bose, Neelanjan; Meyer, Jan M; Yim, Joshua J; Mayer, Melanie G; Markov, Gabriel V; Ogawa, Akira; Schroeder, Frank C; Sommer, Ralf J
2014-07-07
Dauer formation, a major nematode survival strategy, represents a model for small-molecule regulation of metazoan development [1-10]. Free-living nematodes excrete dauer-inducing pheromones that have been assumed to target conspecifics of the same genotype [9, 11]. However, recent studies in Pristionchus pacificus revealed that the dauer pheromone of some strains affects conspecifics of other genotypes more strongly than individuals of the same genotype [12]. To elucidate the mechanistic basis for this intriguing cross-preference, we compared six P. pacificus wild isolates to determine the chemical composition of their dauer-inducing metabolomes and responses to individual pheromone components. We found that these isolates produce dauer pheromone blends of different composition and respond differently to individual pheromone components. Strikingly, there is no correlation between production of and dauer response to a specific compound in individual strains. Specifically, pheromone components that are abundantly produced by one genotype induce dauer formation in other genotypes, but not necessarily in the abundant producer. Furthermore, some genotypes respond to pheromone components they do not produce themselves. These results support a model of intraspecific competition in nematode dauer formation. Indeed, we observed intraspecific competition among sympatric strains in a novel experimental assay, suggesting a new role of small molecules in nematode ecology. Copyright © 2014 Elsevier Ltd. All rights reserved.
19. Pheromones and pheromone receptors are required for proper sexual development in the homothallic ascomycete Sordaria macrospora.
Science.gov (United States)
Mayrhofer, Severine; Weber, Jan M; Pöggeler, Stefanie
2006-03-01
The homothallic, filamentous ascomycete Sordaria macrospora is self-fertile and produces sexual fruiting bodies (perithecia) without a mating partner. Even so, S. macrospora transcriptionally expresses two pheromone-precursor genes (ppg1 and ppg2) and two pheromone-receptor genes (pre1 and pre2). The proteins encoded by these genes are similar to alpha-factor-like and a-factor-like pheromones and to G-protein-coupled pheromone receptors of the yeast Saccharomyces cerevisiae. It has been suggested that in S. macrospora, PPG1/PRE2 and PPG2/PRE1 form two cognate pheromone-receptor pairs. To investigate their function, we deleted (delta) pheromone-precursor genes (delta ppg1, delta ppg2) and receptor genes (delta pre1, delta pre2) and generated single- as well as double-knockout strains. No effect on vegetative growth, fruiting-body, and ascospore development was seen in the single pheromone-mutant and receptor-mutant strains, respectively. However, double-knockout strains lacking any compatible pheromone-receptor pair (delta pre2/delta ppg2, delta pre1/delta ppg1) and the double-pheromone mutant (delta ppg1/delta ppg2) displayed a drastically reduced number of perithecia and sexual spores, whereas deletion of both receptor genes (delta pre1/delta pre2) completely eliminated fruiting-body and ascospore formation. The results suggest that pheromones and pheromone receptors are required for optimal sexual reproduction of the homothallic S. macrospora.
20. Multi-functional roles of a soldier-specific volatile as a worker arrestant, primer pheromone and an antimicrobial agent in a termite.
Science.gov (United States)
Mitaka, Yuki; Mori, Naoki; Matsuura, Kenji
2017-07-26
Division of labour in eusocial insects is characterized by efficient communication systems based on pheromones. Among such insects, termites have evolved specialized sterile defenders, called soldiers. Because they are incapable of feeding themselves, it has been suggested that soldiers are sustained by workers and emit the pheromone arresting workers. However, such a soldier pheromone has not been identified in any termite species, and the details of the soldier-worker interaction remain to be explored. Here, we identified a soldier-specific volatile sesquiterpene as a worker arrestant, which also acts as a primer pheromone regulating soldier differentiation and fungistatic agent in a termite Reticulitermes speratus Chemical analyses revealed that (-)- β -elemene is the major component of soldier extract, and its authentic standard exhibited arrestant activity to workers and inhibited the differentiation from workers to soldiers. This compound also showed fungistatic activity against entomopathogenic fungi. These suggest that (-)- β -elemene secreted by soldiers acts not only as a worker arrestant but also as one component of inhibitory primer pheromone and an anti-pathogenic agent. Our study provides novel evidence supporting the multi-functionality of termite soldier pheromone and provides new insights into the role of soldiers and the evolutionary mechanisms of pheromone compounds. © 2017 The Author(s).
1. Attraction Pheromone of The Benthic Diatom Seminavis robusta: Studies on Structure-Activity Relationships.
Science.gov (United States)
Lembke, Christine; Stettin, Daniel; Speck, Franziska; Ueberschaar, Nico; De Decker, Sam; Vyverman, Wim; Pohnert, Georg
2018-04-01
Recently the first pheromone of a marine diatom was identified to be the diketopiperazine (S,S)-diproline. This compound facilitates attraction between mating partners in the benthic diatom Seminavis robusta. Interestingly, sexualized S. robusta cells are attracted to both the natural pheromone (S,S)-diproline as well as to its enantiomer (R,R)-diproline. Usually stereospecificity is a prerequisite for successful substrate-receptor interactions, and especially pheromone perception is often highly enantioselective. Here we introduce a structure-activity relationship study, to learn more about the principles of pheromone reception in diatoms. We analyzed the activity of nine different diketopiperazines in attraction and interference assays. The pheromone diproline itself, as well as a pipecolic acid derived diketopiperazine with two expanded aliphatic ring systems, showed the highest attractivity. Hydroxylatoin of the aliphatic rings abolished any bioactivity. Diketopiperazines derived from acyclic amino acids were not attrative as well. All stereoisomers of both the diproline and the pipecolic acid derived diketopiperazine were purified by enantioselective high-performance liquid chromatography, and application in bioactivity tests confirmed that attraction pheromone perception in this diatom is indeed not stereospecific. However, the lack of activity of diketopiperazines derived from acyclic amino acids suggests a specificity that prevents misguidance to sources of other naturally occurring diketopiperazines.
2. IT’S ALL IN THE MIX: BLEND-SPECIFIC BEHAVIOURAL RESPONSE TO A SEXUAL PHEROMONE IN A BUTTERFLY
Directory of Open Access Journals (Sweden)
Helena eLarsdotter-Mellström
2016-02-01
Full Text Available Among insects, sexual pheromones are typically mixtures of two to several components, all of which are generally required to elicit a behavioural response. Here we show for the first time that a complete blend of sexual pheromone components is needed to elicit a response also in a butterfly. Males of the Green-veined White, Pieris napi, emit an aphrodisiac pheromone, citral, from wing glands. This pheromone is requisite for females to accept mating with a courting male. Citral is a mixture of the two geometric isomers geranial (E-isomer and neral (Z-isomer in an approximate 1:1 ratio. We found that both these compounds are required to elicit acceptance behaviour, which indicates synergistic interaction between processing of the isomers. Using functional Ca2+ imaging we found that geranial and neral evoke significantly different but overlapping glomerular activity patterns in the antennal lobe, which suggests receptors with different affinity for the two isomers. However, these glomeruli were intermingled with glomeruli responding to ,for example, plant-related compounds, i.e. no distinct subpopulation of pheromone-responding glomeruli as in moths and other insects. In addition, these glomeruli showed lower specificity than pheromone-activated glomeruli in moths. We could, however, not detect any mixture interactions among four identified glomeruli, indicating that the synergistic effect may be generated at a higher processing level. Furthermore, correlations between glomerular activity patterns evoked by the single isomers and the blend did not change over time.
3. Molecular switches for pheromone release from a moth pheromone-binding protein
International Nuclear Information System (INIS)
Xu Wei; Leal, Walter S.
2008-01-01
Pheromone-binding proteins (PBPs) are involved in the uptake of pheromones from pores on the antennae, transport through an aqueous environment surrounding the olfactory receptor neurons, and fast delivery to pheromone receptors. We tested the hypothesis that a C-terminal segment and a flexible loop are involved in the release of pheromones to membrane-bound receptors. We expressed in Escherichia coli 11 mutants of the PBP from the silkworm moth, BmorPBP, taking into consideration structural differences between the forms with high and low binding affinity. The N-terminus was truncated and His-69, His-70 and His-95 at the base of a flexible loop, and a cluster of acidic residues at the C-terminus were mutated. Binding assays and circular dichroism analyses support a mechanism involving protonation of acidic residues Asp-132 and Glu-141 at the C-terminus and histidines, His-70 and His-95, in the base of a loop covering the binding pocket. The former leads to the formation of a new α-helix, which competes with pheromone for the binding pocket, whereas positive charge repulsion of the histidines opens the opposite side of the binding pocket
4. Pheromonal Cues Deposited by Mated Females Convey Social Information about Egg-Laying Sites in Drosophila Melanogaster.
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Duménil, Claire; Woud, David; Pinto, Francesco; Alkema, Jeroen T; Jansen, Ilse; Van Der Geest, Anne M; Roessingh, Sanne; Billeter, Jean-Christophe
2016-03-01
Individuals can make choices based on information learned from others, a phenomenon called social learning. How observers differentiate between which individual they should or should not learn from is, however, poorly understood. Here, we showed that Drosophila melanogaster females can influence the choice of egg-laying site of other females through pheromonal marking. Mated females mark territories of high quality food by ejecting surplus male sperm containing the aggregation pheromone cis-11-vaccenyl acetate (cVA) and, in addition, deposit several sex- and species-specific cuticular hydrocarbon (CHC) pheromones. These pheromonal cues affect the choices of other females, which respond by preferentially laying eggs on the marked food. This system benefits both senders and responders, as communal egg laying increases offspring survival. Virgin females, however, do not elicit a change in the egg-laying decision of mated females, even when food has been supplemented with ejected sperm from mated females, thus indicating the necessity for additional cues. Genetic ablation of either a female's CHC pheromones or those of their mate results in loss of ability of mated females to attract other females. We conclude that mated females use a pheromonal marking system, comprising cVA acquired from male ejaculate with sex- and species-specific CHCs produced by both mates, to indicate egg-laying sites. This system ensures information reliability because mated, but not virgin, females have both the ability to generate the pheromone blend that attracts other flies to those sites and a direct interest in egg-laying site quality.
5. Odour-mediated foraging by yellowjacket wasps (Hymenoptera: Vespidae): predation on leks of pheromone-calling Mediterranean fruit fly males (Diptera: Tephritidae).
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Hendrichs, J; Katsoyannos, B I; Wornoayporn, V; Hendrichs, M A
1994-09-01
Predation is probably the most important male mortality factor in insect species with courtship displays that render males performing them conspicuous targets of predators. Sexually active Mediterranean fruit fly males, Ceratitis capitata (Wied.), aggregate in leks, where they participate in agonistic encounters and engage in visual, acoustic and pheromone-calling displays to attract receptive females. The objective of this study was to assess: a) whether sexually displaying C. capitata males in leks inside host and non-host foliage are subject to predation by the most prominent predators yellow-jacket wasps, Vespula germanica (F.), and if so, b) whether olfactory, visual or auditive stimuli are used by foraging wasps in locating male C. capitata prey. Studies were carried out in a citrus orchard and surroundings on the island of Chios, Greece. Observations were conducted using perforated containers hung within mulberry, fig or citrus foliage. Living C. capitata flies of different sex and either mature or immature were placed inside. Our results show that the yellowjacket wasps have learned to associate the presence of sexually active medfly males aggregated in leks with their prey's pheromone (kairomone). Foraging wasps, flying through the crowns of host trees, responded to the odour source of C. capitata male pheromone by approaching from downwind. Even inside dense citrus tree foliage, wasps keyed in on aggregations of pheromone-calling males using olfactory stimuli. Stimuli of visual and acoustic male signalling were only used at close range, after having followed the pheromone plume close to its source. Visual cues played a greater role in directing wasp foraging under more open and exposed host foliage conditions. Odour-based foraging of wasps inside host foliage in the mid-morning hours, when medfly male lekking activities peak, shifted gradually to a more visual-based host fruit patrolling in the afternoons to capture ovipositing and feeding medfly females
6. A conserved neuronal DAF-16/FoxO plays an important role in conveying pheromone signals to elicit repulsion behavior in Caenorhabditis elegans.
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Park, Donha; Hahm, Jeong-Hoon; Park, Saeram; Ha, Go; Chang, Gyeong-Eon; Jeong, Haelim; Kim, Heekyeong; Kim, Sunhee; Cheong, Eunji; Paik, Young-Ki
2017-08-03
Animals use pheromones as a conspecific chemical language to respond appropriately to environmental changes. The soil nematode Caenorhabditis elegans secretes ascaroside pheromones throughout the lifecycle, which influences entry into dauer phase in early larvae, in addition to sexual attraction and aggregation. In adult hermaphrodites, pheromone sensory signals perceived by worms usually elicit repulsion as an initial behavioral signature. However, the molecular mechanisms underlying neuronal pheromone sensory process from perception to repulsion in adult hermaphrodites remain poorly understood. Here, we show that pheromone signals perceived by GPA-3 is conveyed through glutamatergic neurotransmission in which neuronal DAF-16/FoxO plays an important modulatory role by controlling glutaminase gene expression. We further provide evidence that this modulatory role for DAF-16/FoxO seems to be conserved evolutionarily by electro-physiological study in mouse primary hippocampal neurons that are responsible for glutamatergic neurotransmission. These findings provide the basis for understanding the nematode pheromone signaling, which seems crucial for adaptation of adult hermaphrodites to changes in environmental condition for survival.
7. Sex in the night: fatty acid-derived sex pheromones and corresponding membrane pheromone receptors in insects.
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Koutroumpa, Fotini A; Jacquin-Joly, Emmanuelle
2014-12-01
The moth sex pheromone communication is one of the most striking examples of chemical communication in the animal kingdom. Investigating the molecular mechanisms of pheromone biosynthesis in the female pheromone gland and of pheromone reception in the male antennae not only defines new concepts in signalling research but also opens new perspectives for insect control. In this mini-review, we use the cotton leafworm Spodoptera littoralis as a guideline to illustrate the recent advances gained in the understanding of moth sex pheromone communication. Copyright © 2014 Elsevier Masson SAS. All rights reserved.
8. SNMP is a signaling component required for pheromone sensitivity in Drosophila.
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Jin, Xin; Ha, Tal Soo; Smith, Dean P
2008-08-05
The only known volatile pheromone in Drosophila, 11-cis-vaccenyl acetate (cVA), mediates a variety of behaviors including aggregation, mate recognition, and sexual behavior. cVA is detected by a small set of olfactory neurons located in T1 trichoid sensilla on the antennae of males and females. Two components known to be required for cVA reception are the odorant receptor Or67d and the extracellular pheromone-binding protein LUSH. Using a genetic screen for cVA-insensitive mutants, we have identified a third component required for cVA reception: sensory neuron membrane protein (SNMP). SNMP is a homolog of CD36, a scavenger receptor important for lipoprotein binding and uptake of cholesterol and lipids in vertebrates. In humans, loss of CD36 is linked to a wide range of disorders including insulin resistance, dyslipidemia, and atherosclerosis, but how CD36 functions in lipid transport and signal transduction is poorly understood. We show that SNMP is required in pheromone-sensitive neurons for cVA sensitivity but is not required for sensitivity to general odorants. Using antiserum to SNMP infused directly into the sensillum lymph, we show that SNMP function is required on the dendrites of cVA-sensitive neurons; this finding is consistent with a direct role in cVA signal transduction. Therefore, pheromone perception in Drosophila should serve as an excellent model to elucidate the role of CD36 members in transmembrane signaling.
9. Counter-perfume: using pheromones to prevent female remating.
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Malouines, Clara
2017-08-01
Strong selection to secure paternity in polyandrous species leads to the evolution of numerous chemicals in the male's seminal content. These include antiaphrodisiac pheromones, which are transmitted from the male to the female during mating to render her unattractive to subsequent males. An increasing number of species have been shown to use these chemicals. Herein, I examine the taxonomic distribution of species using antiaphrodisiac pheromones, the selection pressures driving their evolution in both males and females, and the ecological interactions in which these pheromones are involved. The literature review shows a highly skewed distribution of antiaphrodisiac use; all species currently known to use them are insects with the exception of the garter snakes Thamnophis sirtalis parietalis and T. radix. Nonetheless, many taxa have not yet been tested for the presence of antiaphrodisiacs, in groups both closely and distantly related to species known to express them. Within the Insecta, there have been multiple cases of convergent evolution of antiaphrodisiac pheromones using different chemical compounds and methods of transmission. Antiaphrodisiacs usually benefit males, but their effect on females is variable as they can either prevent them from mating multiple times or help them reduce male harassment when they are unreceptive. Some indirect costs of antiaphrodisiacs also impact both males and females, but more research is needed to determine how general this pattern is. Additional research is also important to understand how antiaphrodisiacs interact with the reproductive biology and sexual communication in different species. © 2016 Cambridge Philosophical Society.
10. Ovarian steroid sulphate functions as priming pheromone in male ...
Unknown
The study reveals that pre-ovulatory females of the fish Barilius bendelisis (Ham.) release sex steroids and their conjugates into the water and that a steroid sulphate of these compounds functions as a potent sex pheromone which stimulates milt production in conspecific males prior to spawning. Since males exposed to the ...
11. Genes involved in sex pheromone biosynthesis of Ephestia cautella, an important food storage pest, are determined by transcriptome sequencing
KAUST Repository
Antony, Binu
2015-07-18
Background Insects use pheromones, chemical signals that underlie all animal behaviors, for communication and for attracting mates. Synthetic pheromones are widely used in pest control strategies because they are environmentally safe. The production of insect pheromones in transgenic plants, which could be more economical and effective in producing isomerically pure compounds, has recently been successfully demonstrated. This research requires information regarding the pheromone biosynthetic pathways and the characterization of pheromone biosynthetic enzymes (PBEs). We used Illumina sequencing to characterize the pheromone gland (PG) transcriptome of the Pyralid moth, Ephestia cautella, a destructive storage pest, to reveal putative candidate genes involved in pheromone biosynthesis, release, transport and degradation. Results We isolated the E. cautella pheromone compound as (Z,E)-9,12-tetradecadienyl acetate, and the major pheromone precursors 16:acyl, 14:acyl, E14-16:acyl, E12-14:acyl and Z9,E12-14:acyl. Based on the abundance of precursors, two possible pheromone biosynthetic pathways are proposed. Both pathways initiate from C16:acyl-CoA, with one involving ∆14 and ∆9 desaturation to generate Z9,E12-14:acyl, and the other involving the chain shortening of C16:acyl-CoA to C14:acyl-CoA, followed by ∆12 and ∆9 desaturation to generate Z9,E12-14:acyl-CoA. Then, a final reduction and acetylation generates Z9,E12-14:OAc. Illumina sequencing yielded 83,792 transcripts, and we obtained a PG transcriptome of ~49.5 Mb. A total of 191 PBE transcripts, which included pheromone biosynthesis activating neuropeptides, fatty acid transport proteins, acetyl-CoA carboxylases, fatty acid synthases, desaturases, β-oxidation enzymes, fatty acyl-CoA reductases (FARs) and fatty acetyltransferases (FATs), were selected from the dataset. A comparison of the E. cautella transcriptome data with three other Lepidoptera PG datasets revealed that 45 % of the sequences were shared
12. Queen pheromones
Science.gov (United States)
2010-01-01
Group-living species produce signals that alter the behavior and even the physiology of their social partners. Social insects possess especially sophisticated chemical communication systems that govern every aspect of colony life, including the defining feature of eusociality: reproductive division of labor. Current evidence hints at the central importance of queen pheromones, but progress has been hindered by the fact that such pheromones have only been isolated in honeybees. In a pair of papers on the ant Lasius niger, we identified and investigated a queen pheromone regulating worker sterility. The cuticular hydrocarbon 3-methylhentriacontane (3-MeC31) is correlated with queen maturity and fecundity and workers are also more likely to execute surplus queens that have low amounts of this chemical. Experiments with synthetic 3-MeC31 found that it inhibits ovarian development in queenless workers and lowers worker aggression towards objects coated with it. Production of 3-MeC31 by queens was depressed by an experimental immune challenge, and the same chemical was abundant on queenlaid eggs, suggesting that the workers' responses to the queen are conditional on her health and fecundity. Together with other studies, these results indicate that queen pheromones are honest signals of quality that simultaneously regulate multiple social behaviors. PMID:21331238
13. The evolution of female sex pheromones
Directory of Open Access Journals (Sweden)
2013-08-01
Full Text Available The role of female sex pheromones in natural selection, particularly as a means for species recognition to avoid the generation of hybrid offspring with low fitness, has been widely explored and is generally accepted by scholars. However, the significance of sex pheromones in shaping mate choice (sexual selection and in competition over breeding resources (social selection has been largely ignored. The effect of sexual selection on sex pheromones as a sexually dimorphic signaling trait has been discounted because the amount of pheromone released by females is typically minute, while the role of sex pheromones in competition over breeding resources (other than mates has not yet been considered. As a result of natural selection, variation in sex pheromones among females is expected to be low, and males are not expected to choose their mates among pheromone-releasing conspecific females. Sexual selection, on the other hand, should drive the increase in pheromone variance among females, and males are expected to choose females based on this variation. Moreover, social selection resulting from more general social interactions, for example competition among females for breeding sites and food, should also promote variance among female sex pheromones. Here, we review the current evidence for each of the three selection processes acting on sex pheromones of female moths as an advertising trait. We suggest that the three selection types are not mutually exclusive but rather act together to promote different fitness components in diverse ecological situations [Current Zoology 59 (4: 569–578, 2013].
14. Sex Pheromone and Trail Pheromone of the Sand Termite Psammotermes hybostoma
Czech Academy of Sciences Publication Activity Database
Sillam-Dusses, David; Hanus, Robert; Abd El-Latif, A. O.; Jiroš, Pavel; Krasulová, Jana; Kalinová, Blanka; Valterová, Irena; Šobotník, Jan
2011-01-01
Roč. 37, č. 2 (2011), s. 179-188 ISSN 0098-0331 R&D Projects: GA ČR GAP506/10/1570 Institutional research plan: CEZ:AV0Z40550506 Keywords : sex pheromone * trail pheromone * Psammotermes hybostoma * termites * Rhinotermitidae Subject RIV: CC - Organic Chemistry Impact factor: 2.657, year: 2011
15. Role of solid-phase microextraction in the identification of highly volatile pheromones of two Rhinoceros beetles Scapanes australis and Strategus aloeus (Coleoptera, Scarabaeidae, Dynastinae).
Science.gov (United States)
Rochat, D; Ramirez-Lucas, P; Malosse, C; Aldana, R; Kakul, T; Morin, J P
2000-07-14
Solid-phase microextraction (SPME) samplings from live insects or natural secretion allowed one to identify the aggregation pheromones of the pest beetles Scapanes australis and Strategus aloeus by efficient and rapid isolation of their highly volatile (72 < M(r) < 116) components. S. australis male pheromone was identified as a 84:12:4 (w/w) mixture of 2-butanol [67:33 (R)-(-):(S)-(+) ratio], 3-hydroxy-2-butanone and 2,3-butanediol [43:17:40 (R,R)-(-):(S,S)-(+):meso ratio], and S. aloeus pheromone as a 95.5:4.0:0.5 (w/w) mixture of 2-butanone, 3-pentanone and sec.-butyl acetate by GC-MS using conventional and chiral capillary columns. This is the first report of Scarabaeidae pheromones based on such small and common molecules.
16. Discrimination of bile acids by the rainbow trout olfactory system: Evidence as potential pheromone
Directory of Open Access Journals (Sweden)
PERCILIA C GIAQUINTO
2008-01-01
Full Text Available Electro-olfactogram recording was used to determine whether the olfactory epithelium of adult rainbow trout is specifically sensitive to bile acids, some of which have been hypothesized to function as pheromones. Of 38 bile acids that had been pre-screened for olfactory activity, 6 were selected. The rainbow trout-specific bile acids, taurocholic acid (TCA, and taurolithocholic acid 3-sulfate (TLS were the most potent compounds tested. TLS had a distinctive dose-response curve. Cross-adaptation experiments demonstrated that sensitivity to bile acids is attributable to at least 3 independent classes of olfactory receptor sites. Our data suggest that bile acids are discriminated by olfaction in rainbow trout, supporting the possibility that these compounds function as pheromones
17. Verbenone: Dose-Dependent Interruption of Pheromone-Based Attraction of Three Sympatric Species of Pine Bark Beetles (Coleoptera: Scolytidae)
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Daniel R. Miller; John H. Borden; B. Staffan Lindgren
1995-01-01
Verbenone significantly reduced catches of Ips latidens (LeConte), I. pini (Say), and Dendroctonus ponderosae Hopkins in multiple-funnel traps, baited with aggregation pheromones, in stands of lodgepole pine in southern British Columbia. Interruption of attraction was dose dependent for all three species. There...
18. Evidence for the presence of a female produced sex pheromone in the banana weevil, Cosmopolites sordidus Germar (Coleoptera: Curculionidae)
Science.gov (United States)
Behavior-modifying chemicals such as pheromones and kairomones have great potential in pest management. Studies reported here investigated chemical cues involved in mating and aggregation behavior of banana weevil, Cosmopolites sordidus, a major insect pest of banana in every country where bananas a...
19. The use of lithium compounds for inhibiting alkali-aggregate reaction effects in pavement structures
Science.gov (United States)
Zapała-Sławeta, J.; Owsiak, Z.
2018-05-01
Internal corrosion of concrete caused by the reaction of reactive aggregate with sodium and potassium hydroxides from cement is a threat to the durability of concrete pavements. Traditional methods for reducing the negative effects of the reaction include the use of unreactive aggregates, low alkali cements, mineral additives or chemical admixtures, incorporated during mixing. Lowering the relative humidity of the concrete below 80% is another measure for limiting the destructive reaction. The incorporation of lithium compounds, in particular lithium nitrate and lithium hydroxide, to the concrete mix is a method of limiting alkali-silica reaction effects. The challenge is to reduce the negative effects of aggregate reactivity in members in which the reaction has occurred because the aggregate happened to be reactive. The paper presents ways of limiting the deterioration of ASR-affected concrete in road pavements and other forms of transportation infrastructure, mainly through the use of lithium compounds, i.e. lithium nitrate. Impregnation methods that allow the penetration of lithium ions into the concrete structure were characterized, as was the effectiveness of the solutions applied.
20. Do pheromones reveal male immunocompetence?
Science.gov (United States)
Rantala, Markus J; Jokinen, Ilmari; Kortet, Raine; Vainikka, Anssi; Suhonen, Jukka
2002-01-01
Pheromones function not only as mate attractors, but they may also relay important information to prospective mates. It has been shown that vertebrates can distinguish, via olfactory mechanisms, major histocompatibility complex types in their prospective mates. However, whether pheromones can transmit information about immunocompetence is unknown. Here, we show that female mealworm beetles (Tenebrio molitor) prefer pheromones from males with better immunocompetence, indicated by a faster encapsulation rate against a novel antigen, and higher levels of phenoloxidase in haemolymph. Thus, the present study indicates that pheromones could transmit information about males' parasite resistance ability and may work as a reliable sexual ornament for female choice. PMID:12204128
1. Host plant odours enhance the responses of adult banana weevil to the synthetic aggregation pheromone Cosmolure+
NARCIS (Netherlands)
Tinzaara, W.; Gold, C.S.; Dicke, M.; Huis, van A.; Ragama, P.E.
2007-01-01
Attraction of adult banana weevil, Cosmopolites sordidus to volatiles from banana pseudostem tissue and the synthetic pheromone Cosmolure+ presented singly or in combination, was studied in the laboratory and in the field. Olfactometric studies in the laboratory showed that 50 g of fermented banana
2. Silent genes and rare males: A fresh look at pheromone blend response specificity in the European corn borer moth, Ostrinia nubilalis
Directory of Open Access Journals (Sweden)
Charles Linn Jr.
2003-05-01
Full Text Available The response of male moths from two pheromone races of the European corn borer, Ostrinia nubilalis, was measured in a flight tunnel assay to different ratios of structurally different compounds that comprise the sex pheromone of the Asian corn borer, Ostrinia furnacalis. For both O. nubilalis races, between 1 and 5% of the males completed upwind flights to two different blends of the O. furnacalis pheromone components (the 2:1 Z/E12-14:OAc female-produced blend, and a 97:3 Z/E mix, confirming that rare males exist in the O. nubilalis populations that can detect and respond to mixtures of the O. furnacalis pheromone components. Rare males that responded to the O. furnacalis blends also responded to their own O. nubilalis blends (97:3 or 1:99 Z/E11-14:OAc, indicating that rare O. nubilalis males are not preferentially sensitive to mixtures of the O. furnacalis compounds, but rather that they have a broad range of response specificity, which includes recognition of a wide range of conspecific female-produced ratios, and also recognition of heterospecific mixtures. The results support the hypothesis that saltational shifts in pheromone blend composition (Roelofs et al., 2002 can lead to the evolution of a new species-specific communication system, in part because the broad response specificity of some males includes the ability to respond in an agonistic manner to novel mixtures of compounds.
3. Pheromones in White Pine Cone Beetle, Conophthorus coniperdu (Schwarz) (Coleoptera: Scolytidae)
Science.gov (United States)
Goran Birgersson; Gary L. DeBarr; Peter de Groot; Mark J. Dalusky; Harold D. Pierce; John H. Borden; Holger Meyer; Wittko Francke; Karl E. Espelie; C. Wayne Berisford
1995-01-01
Female white pine cone beetles, Conophrhorus coniperda, attacking second-year cones of eastern white pine, Pinus strobus L., produced a sex-specific pheromone that attracted conspecific males in laboratory bioassays and to field traps. Beetle response was enhanced by host monoterpenes. The female-produced compound was identified in...
4. Manipulation of insect behavior with Specialized Pheromone & Lure Application Technology (SPLAT®)
Science.gov (United States)
Agenor Mafra-Neto; Frédérique M. de Lame; Christopher J. Fettig; A. Steven Munson; Thomas M. Perring; Lukasz L. Stelinski; Lyndsie Stoltman; Leandro E.J. Mafra; Rafael Borges; Roger I. Vargas
2013-01-01
SPLAT® (Specialized Pheromone and Lure Application Technology) emulsion is a unique controlled-release technology that can be adapted to dispense and protect a wide variety of compounds from degradation, including semiochemicals, pesticides, and phagostimulants, in diverse environments. ISCA Technologies, Inc., in collaboration with colleagues in academia, government,...
5. Understanding the logics of pheromone processing in the honeybee brain: from labeled-lines to across-fiber patterns
Directory of Open Access Journals (Sweden)
Nina Deisig
2007-12-01
Full Text Available Honeybees employ a very rich repertoire of pheromones to ensure intraspecific communication in a wide range of behavioral contexts. This communication can be complex, since the same compounds can have a variety of physiological and behavioral effects depending on the receiver. Honeybees constitute an ideal model to study the neurobiological basis of pheromonal processing, as they are already one of the most infl uential animal models for the study of general odor processing and learning at behavioral, cellular and molecular levels. Accordingly, the anatomy of the bee brain is well characterized and electro- and opto-physiological recording techniques at different stages of the olfactory circuit are possible in the laboratory. Here we review pheromone communication in honeybees and analyze the different stages of olfactory processing in the honeybee brain, focusing on available data on pheromone detection, processing and representation at these different stages. In particular, we argue that the traditional distinction between labeled-line and across-fi ber pattern processing, attributed to pheromone and general odors respectively, may not be so clear in the case of honeybees, especially for social-pheromones. We propose new research avenues for stimulating future work in this area.
6. A new class of mealybug pheromones: a hemiterpene ester in the sex pheromone of Crisicoccus matsumotoi
Science.gov (United States)
Tabata, Jun; Narai, Yutaka; Sawamura, Nobuo; Hiradate, Syuntaro; Sugie, Hajime
2012-07-01
Mealybugs, which include several agricultural pests, are small sap feeders covered with a powdery wax. They exhibit clear sexual dimorphism; males are winged but fragile and short lived, whereas females are windless and less mobile. Thus, sex pheromones emitted by females facilitate copulation and reproduction by serving as a key navigation tool for males. Although the structures of the hitherto known mealybug pheromones vary among species, they have a common structural motif; they are carboxylic esters of monoterpene alcohols with irregular non-head-to-tail linkages. However, in the present study, we isolated from the Matsumoto mealybug, Crisicoccus matsumotoi (Siraiwa), a pheromone with a completely different structure. Using gas chromatography-mass spectrometry and nuclear magnetic resonance spectroscopy, we identified the pheromone as 3-methyl-3-butenyl 5-methylhexanoate. Its attractiveness to males was confirmed in a series of field trapping experiments involving comparison between the isolated natural product and a synthetic sample. This is the first report of a hemiterpene mealybug pheromone. In addition, the acid moiety (5-methylhexanoate) appears to be rare in insect pheromones.
7. Characterization of Odorant Receptors from a Non-ditrysian Moth, Eriocrania semipurpurella Sheds Light on the Origin of Sex Pheromone Receptors in Lepidoptera.
Science.gov (United States)
Yuvaraj, Jothi Kumar; Corcoran, Jacob A; Andersson, Martin N; Newcomb, Richard D; Anderbrant, Olle; Löfstedt, Christer
2017-11-01
Pheromone receptors (PRs) are essential in moths to detect sex pheromones for mate finding. However, it remains unknown from which ancestral proteins these specialized receptors arose. The oldest lineages of moths, so-called non-ditrysian moths, use short-chain pheromone components, secondary alcohols, or ketones, so called Type 0 pheromones that are similar to many common plant volatiles. It is, therefore, possible that receptors for these ancestral pheromones evolved from receptors detecting plant volatiles. Hence, we identified the odorant receptors (ORs) from a non-ditrysian moth, Eriocrania semipurpurella (Eriocraniidae, Lepidoptera), and performed functional characterization of ORs using HEK293 cells. We report the first receptors that respond to Type 0 pheromone compounds; EsemOR3 displayed highest sensitivity toward (2S, 6Z)-6-nonen-2-ol, whereas EsemOR5 was most sensitive to the behavioral antagonist (Z)-6-nonen-2-one. These receptors also respond to plant volatiles of similar chemical structures, but with lower sensitivity. Phylogenetically, EsemOR3 and EsemOR5 group with a plant volatile-responding receptor from the tortricid moth Epiphyas postvittana (EposOR3), which together reside outside the previously defined lepidopteran PR clade that contains the PRs from more derived lepidopteran families. In addition, one receptor (EsemOR1) that falls at the base of the lepidopteran PR clade, responded specifically to β-caryophyllene and not to any other additional plant or pheromone compounds. Our results suggest that PRs for Type 0 pheromones have evolved from ORs that detect structurally-related plant volatiles. They are unrelated to PRs detecting pheromones in more derived Lepidoptera, which, in turn, also independently may have evolved a novel function from ORs detecting plant volatiles. © The Author 2017. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution.
8. Sublethal Effects of Neonicotinoid Insecticide on Calling Behavior and Pheromone Production of Tortricid Moths.
Science.gov (United States)
Navarro-Roldán, Miguel A; Gemeno, César
2017-09-01
In moths, sexual behavior combines female sex pheromone production and calling behavior. The normal functioning of these periodic events requires an intact nervous system. Neurotoxic insecticide residues in the agroecosystem could impact the normal functioning of pheromone communication through alteration of the nervous system. In this study we assess whether sublethal concentrations of the neonicotinoid insecticide thiacloprid, that competitively modulates nicotinic acetylcholine receptors at the dendrite, affect pheromone production and calling behavior in adults of three economically important tortricid moth pests; Cydia pomonella (L.), Grapholita molesta (Busck), and Lobesia botrana (Denis & Schiffermüller). Thiacloprid significantly reduced the amount of calling in C. pomonella females at LC 0.001 (a lethal concentration that kills only 1 in 10 5 individuals), and altered its calling period at LC 1 , and in both cases the effect was dose-dependent. In the other two species the effect was similar but started at higher LCs, and the effect was relatively small in L. botrana. Pheromone production was altered only in C. pomonella, with a reduction of the major compound, codlemone, and one minor component, starting at LC 10 . Since sex pheromones and neonicotinoids are used together in the management of these three species, our results could have implications regarding the interaction between these two pest control methods.
9. Female Sex Pheromone in Trails of the Minute Pirate Bug, Orius minutus (L).
Science.gov (United States)
Maeda, Taro; Fujiwara-Tsujii, Nao; Yasui, Hiroe; Matsuyama, Shigeru
2016-05-01
Orius minutus (L.) (Heteroptera: Anthocoridae) is a natural enemy of agricultural pests such as thrips, aphids, and various newly hatched insect juveniles. In this study, we conducted 1) behavioral assays for evidence of contact sex pheromone activity in trails of O. minutus, and 2) chemical analysis to identify the essential chemical components of the trails. Males showed arrestment to trails of mature virgin females but not to trails from either conspecific nymphs or immature females. Females also showed arrestment to trails from conspecific males, although the response was weaker than that exhibited by males. The activity of female trails lasted for at least 46 h after deposition. Males showed a response irrespective of mating experience. Following confirmation that a contact sex pheromone was present in the trails of female O. minutus, we used a bioassay-driven approach to isolate the active chemicals. After fractionation on silica gel, the n-hexane fraction was found to be biologically active to males. A major compound in the active fraction was (Z)-9-nonacosene; this compound was found only in trail extracts of mature virgin females. Synthetic (Z)-9-nonacosene arrested O. minutus males, indicating that it is the major active component of the contact sex pheromone in the trails of female O. minutus.
10. Pheromone binding proteins enhance the sensitivity of olfactory receptors to sex pheromones in Chilo suppressalis.
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Chang, Hetan; Liu, Yang; Yang, Ting; Pelosi, Paolo; Dong, Shuanglin; Wang, Guirong
2015-08-27
Sexual communication in moths offers a simplified scenario to model and investigate insect sensory perception. Both PBPs (pheromone-binding proteins) and PRs (pheromone receptors) are involved in the detection of sex pheromones, but the interplay between them still remains largely unknown. In this study, we have measured the binding affinities of the four recombinant PBPs of Chilo suppressalis (CsupPBPs) to pheromone components and analogs and characterized the six PRs using the Xenopus oocytes expression system. Interestingly, when the responses of PRs were recorded in the presence of PBPs, we measured in several combinations a dramatic increase in signals as well as in sensitivity of such combined systems. Furthermore, the discrimination ability of appropriate combinations of PRs and PBPs was improved compared with the performance of PBPs or PRs alone. Besides further supporting a role of PBPs in the pheromone detection and discrimination, our data shows for the first time that appropriate combinations of PRs and PBPs improved the discrimination ability of PBPs or PRs alone. The variety of responses measured with different pairing of PBPs and PRs indicates the complexity of the olfaction system, which, even for the relatively simple task of detecting sex pheromones, utilises a highly sophisticated combinatorial approach.
11. Pheromone disruption of Argentine ant trail integrity
Science.gov (United States)
Suckling, D.M.; Peck, R.W.; Manning, L.M.; Stringer, L.D.; Cappadonna, J.; El-Sayed, A. M.
2008-01-01
Disruption of Argentine ant trail following and reduced ability to forage (measured by bait location success) was achieved after presentation of an oversupply of trail pheromone, (Z)-9-hexadecenal. Experiments tested single pheromone point sources and dispersion of a formulation in small field plots. Ant walking behavior was recorded and digitized by using video tracking, before and after presentation of trail pheromone. Ants showed changes in three parameters within seconds of treatment: (1) Ants on trails normally showed a unimodal frequency distribution of walking track angles, but this pattern disappeared after presentation of the trail pheromone; (2) ants showed initial high trail integrity on a range of untreated substrates from painted walls to wooden or concrete floors, but this was significantly reduced following presentation of a point source of pheromone; (3) the number of ants in the pheromone-treated area increased over time, as recruitment apparently exceeded departures. To test trail disruption in small outdoor plots, the trail pheromone was formulated with carnuba wax-coated quartz laboratory sand (1 g quartz sand/0.2 g wax/1 mg pheromone). The pheromone formulation, with a half-life of 30 h, was applied by rotary spreader at four rates (0, 2.5, 7.5, and 25 mg pheromone/m2) to 1- and 4-m2 plots in Volcanoes National Park, Hawaii. Ant counts at bait cards in treated plots were significantly reduced compared to controls on the day of treatment, and there was a significant reduction in ant foraging for 2 days. These results show that trail pheromone disruption of Argentine ants is possible, but a much more durable formulation is needed before nest-level impacts can be expected. ?? 2008 Springer Science+Business Media, LLC.
12. Simultaneously hermaphroditic shrimp use lipophilic cuticular hydrocarbons as contact sex pheromones.
Science.gov (United States)
Zhang, Dong; Terschak, John A; Harley, Maggy A; Lin, Junda; Hardege, Jörg D
2011-04-20
Successful mating is essentially a consequence of making the right choices at the correct time. Animals use specific strategies to gain information about a potential mate, which is then applied to decision-making processes. Amongst the many informative signals, odor cues such as sex pheromones play important ecological roles in coordinating mating behavior, enabling mate and kin recognition, qualifying mate choice, and preventing gene exchange among individuals from different populations and species. Despite overwhelming behavioral evidence, the chemical identity of most cues used in aquatic organisms remains unknown and their impact and omnipresence have not been fully recognized. In many crustaceans, including lobsters and shrimps, reproduction happens through a cascade of events ranging from initial attraction to formation of a mating pair eventually leading to mating. We examined the hypothesis that contact pheromones on the female body surface of the hermaphroditic shrimp Lysmata boggessi are of lipophilic nature, and resemble insect cuticular hydrocarbon contact cues. Via chemical analyses and behavioural assays, we show that newly molted euhermaphrodite-phase shrimp contain a bouquet of odor compounds. Of these, (Z)-9-octadecenamide is the key odor with hexadecanamide and methyl linoleate enhancing the bioactivity of the pheromone blend. Our results show that in aquatic systems lipophilic, cuticular hydrocarbon contact sex pheromones exist; this raises questions on how hydrocarbon contact signals evolved and how widespread these are in the marine environment.
13. Simultaneously hermaphroditic shrimp use lipophilic cuticular hydrocarbons as contact sex pheromones.
Directory of Open Access Journals (Sweden)
Dong Zhang
Full Text Available Successful mating is essentially a consequence of making the right choices at the correct time. Animals use specific strategies to gain information about a potential mate, which is then applied to decision-making processes. Amongst the many informative signals, odor cues such as sex pheromones play important ecological roles in coordinating mating behavior, enabling mate and kin recognition, qualifying mate choice, and preventing gene exchange among individuals from different populations and species. Despite overwhelming behavioral evidence, the chemical identity of most cues used in aquatic organisms remains unknown and their impact and omnipresence have not been fully recognized. In many crustaceans, including lobsters and shrimps, reproduction happens through a cascade of events ranging from initial attraction to formation of a mating pair eventually leading to mating. We examined the hypothesis that contact pheromones on the female body surface of the hermaphroditic shrimp Lysmata boggessi are of lipophilic nature, and resemble insect cuticular hydrocarbon contact cues. Via chemical analyses and behavioural assays, we show that newly molted euhermaphrodite-phase shrimp contain a bouquet of odor compounds. Of these, (Z-9-octadecenamide is the key odor with hexadecanamide and methyl linoleate enhancing the bioactivity of the pheromone blend. Our results show that in aquatic systems lipophilic, cuticular hydrocarbon contact sex pheromones exist; this raises questions on how hydrocarbon contact signals evolved and how widespread these are in the marine environment.
14. Olfactory responses of banana weevil predators to volatiles from banana pseudostem tissue and synthetic pheromone.
Science.gov (United States)
Tinzaara, W; Gold, C S; Dicke, M; van Huis, A
2005-07-01
As a response to attack by herbivores, plants can emit a variety of volatile substances that attract natural enemies of these insect pests. Predators of the banana weevil, Cosmopolites sordidus (Germar) (Coleoptera: Curculionidae) such as Dactylosternum abdominale (Coleoptera: Hydrophilidae) and Pheidole megacephala (Hymenoptera: Formicidae), are normally found in association with weevil-infested rotten pseudostems and harvested stumps. We investigated whether these predators are attracted to such environments in response to volatiles produced by the host plant, by the weevil, or by the weevil plant complex. We evaluated predator responses towards volatiles from banana pseudostem tissue (synomones) and the synthetic banana weevil aggregation pheromone Cosmolure+ in a two-choice olfactometer. The beetle D. abdominale was attracted to fermenting banana pseudostem tissue and Cosmolure+, whereas the ant P. megacephala was attracted only to fermented pseudostem tissue. Both predators were attracted to banana pseudostem tissue that had been damaged by weevil larvae irrespective of weevil presence. Adding pheromone did not enhance predator response to volatiles from pseudostem tissue fed on by weevils. The numbers of both predators recovered with pseudostem traps in the field from banana mats with a pheromone trap were similar to those in pseudostem traps at different distance ranges from the pheromone. Our study shows that the generalist predators D. abdominale and P. megacephala use volatiles from fermented banana pseudostem tissue as the major chemical cue when searching for prey.
15. Effect of storage of pheromone lures for Amyelois transitella: field performance and compound ratios
Science.gov (United States)
Experiments during the flight of the overwintering generation of navel orangeworm revealed that Suterra NOW Biolure pheromone lures held in storage at -20°C increased significantly in field effectiveness with time in storage over a period of 0-2 years. This increase in field effectiveness coincided ...
16. Identification of novel inhibitors of calling and in vitro [14C]acetate incorporation by pheromone glands of Plodia interpunctella.
Science.gov (United States)
Hirashima, A; Eiraku, T; Watanabe, Y; Kuwano, E; Taniguchi, E; Eto, M
2001-08-01
Some octopamine agonists were found to suppress in vitro biosynthesis of the calling pheromone of the Indian meal moth, Plodia interpunctella. Isolated pheromone-gland preparations incorporated sodium [14C]acetate at a linear rate for 3 h when incubated with the pheromone biosynthesis activating neuropeptide (PBAN). This incorporation was dependent on the dose of PBAN (up to 0.5 microM). Thin-layer chromatography of a pheromone-gland extract revealed quantitative incorporation of radioactivity into a product exhibiting the same mobility as (Z,E)-9,12-tetradecadienyl acetate, the main component of the calling pheromone of P interpunctella. Twenty-seven octopamine agonists were initially screened using a calling behaviour bioassay of female P interpunctella. Four derivatives with activity in the nanomolar range were identified which were, in order of decreasing pheromonostatic activity: 2-(2,6-diethylphenylimino)thiazolidine > 2-(2,6-diethylphenylimino)oxazolidine > 2-(2,6-dimethylphenylimino)thiazolidine > 2-(2-ethylphenylimino)oxazolidine. These compounds also showed in vitro inhibitory activity in intracellular de novo pheromone biosynthesis. The results of the present study indicate that these derivatives could provide useful information in the characterization and differentiation of octopaminergic receptor types and subtypes.
17. Geographic Variation in Sexual Attraction of Spodoptera frugiperda Corn- and Rice-Strain Males to Pheromone Lures
Science.gov (United States)
Unbehend, Melanie; Hänniger, Sabine; Vásquez, Gissella M.; Juárez, María Laura; Reisig, Dominic; McNeil, Jeremy N.; Meagher, Robert L.; Jenkins, David A.; Heckel, David G.; Groot, Astrid T.
2014-01-01
The corn- and rice-strains of Spodoptera frugiperda exhibit several genetic and behavioral differences and appear to be undergoing ecological speciation in sympatry. Previous studies reported conflicting results when investigating male attraction to pheromone lures in different regions, but this could have been due to inter-strain and/or geographic differences. Therefore, we investigated whether corn- and rice-strain males differed in their response to different synthetic pheromone blends in different regions in North America, the Caribbean and South America. All trapped males were strain-typed by two strain-specific mitochondrial DNA markers. In the first experiment, we found a nearly similar response of corn- and rice-strain males to two different 4-component blends, resembling the corn- and rice-strain female blend we previously described from females in Florida. This response showed some geographic variation in fields in Canada, North Carolina, Florida, Puerto Rico, and South America (Peru, Argentina). In dose-response experiments with the critical secondary sex pheromone component (Z)-7-dodecenyl acetate (Z7-12:OAc), we found some strain-specific differences in male attraction. While the response to Z7-12:OAc varied geographically in the corn-strain, rice-strain males showed almost no variation. We also found that the minor compound (Z)-11-hexadecenyl acetate (Z11-16:OAc) did not increase attraction of both strains in Florida and of corn-strain males in Peru. In a fourth experiment, where we added the stereo-isomer of the critical sex pheromone component, (E)-7-dodecenyl acetate, to the major pheromone component (Z)-9-tetradecenyl acetate (Z9-14:OAc), we found that this compound was attractive to males in North Carolina, but not to males in Peru. Overall, our results suggest that both strains show rather geographic than strain-specific differences in their response to pheromone lures, and that regional sexual communication differences might cause geographic
18. Geographic variation in sexual attraction of Spodoptera frugiperda corn- and rice-strain males to pheromone lures.
Directory of Open Access Journals (Sweden)
Melanie Unbehend
Full Text Available The corn- and rice-strains of Spodoptera frugiperda exhibit several genetic and behavioral differences and appear to be undergoing ecological speciation in sympatry. Previous studies reported conflicting results when investigating male attraction to pheromone lures in different regions, but this could have been due to inter-strain and/or geographic differences. Therefore, we investigated whether corn- and rice-strain males differed in their response to different synthetic pheromone blends in different regions in North America, the Caribbean and South America. All trapped males were strain-typed by two strain-specific mitochondrial DNA markers. In the first experiment, we found a nearly similar response of corn- and rice-strain males to two different 4-component blends, resembling the corn- and rice-strain female blend we previously described from females in Florida. This response showed some geographic variation in fields in Canada, North Carolina, Florida, Puerto Rico, and South America (Peru, Argentina. In dose-response experiments with the critical secondary sex pheromone component (Z-7-dodecenyl acetate (Z7-12:OAc, we found some strain-specific differences in male attraction. While the response to Z7-12:OAc varied geographically in the corn-strain, rice-strain males showed almost no variation. We also found that the minor compound (Z-11-hexadecenyl acetate (Z11-16:OAc did not increase attraction of both strains in Florida and of corn-strain males in Peru. In a fourth experiment, where we added the stereo-isomer of the critical sex pheromone component, (E-7-dodecenyl acetate, to the major pheromone component (Z-9-tetradecenyl acetate (Z9-14:OAc, we found that this compound was attractive to males in North Carolina, but not to males in Peru. Overall, our results suggest that both strains show rather geographic than strain-specific differences in their response to pheromone lures, and that regional sexual communication differences might cause
19. Presence of Putative Male-Produced Sex Pheromone in Lutzomyia cruciata (Diptera: Psychodidae), Vector of Leishmania mexicana.
Science.gov (United States)
Serrano, A K; Rojas, J C; Cruz-López, L C; Malo, Edi A; Mikery, O F; Castillo, A
2016-11-01
Lutzomyia cruciata (Coquillet) is a vector of cutaneous leishmaniasis in Mexico and Central America. However, several aspects of its ecology and behavior are unknown, including whether a male pheromone partially mediates the sexual behavior of this sand fly. In this study, we evaluated the behavioral response of females to male abdominal extracts in a Y-tube olfactometer. The volatile compounds from male abdominal extracts were identified by gas chromatography-mass spectrometry and compared with those of female abdominal extracts. Finally, the disseminating structures of the putative sex pheromone were examined by scanning electron microscopy in the male abdomen. Females were more attracted to male abdominal extract than to the hexane control, suggesting the presence of male-produced sex pheromone. The male abdominal extracts were characterized by the presence of 12 sesquiterpene compounds. The major component, an unknown sesquiterpene with an abundance of 60%, had a mass spectrum with molecular ion of m/z 262. In contrast, the abdominal female extracts contained saturated fatty acids. Finally, we detected the presence of small "papules" with a mammiform morphology distributed on the abdominal surface of tergites IV-VII of male Lu. cruciata These structures are not present in females. We conclude that Lu. cruciata males likely produce a pheromone involved in attracting or courting females. © The Authors 2016. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For Permissions, please email: journals.permissions@oup.com.
20. Evaluating the binding efficiency of pheromone binding protein with its natural ligand using molecular docking and fluorescence analysis
Science.gov (United States)
Ilayaraja, Renganathan; Rajkumar, Ramalingam; Rajesh, Durairaj; Muralidharan, Arumugam Ramachandran; Padmanabhan, Parasuraman; Archunan, Govindaraju
2014-06-01
Chemosignals play a crucial role in social and sexual communication among inter- and intra-species. Chemical cues are bound with protein that is present in the pheromones irrespective of sex are commonly called as pheromone binding protein (PBP). In rats, the pheromone compounds are bound with low molecular lipocalin protein α2u-globulin (α2u). We reported farnesol is a natural endogenous ligand (compound) present in rat preputial gland as a bound volatile compound. In the present study, an attempt has been made through computational method to evaluating the binding efficiency of α2u with the natural ligand (farnesol) and standard fluorescent molecule (2-naphthol). The docking analysis revealed that the binding energy of farnesol and 2-naphthol was almost equal and likely to share some binding pocket of protein. Further, to extrapolate the results generated through computational approach, the α2u protein was purified and subjected to fluorescence titration and binding assay. The results showed that the farnesol is replaced by 2-naphthol with high hydrophobicity of TYR120 in binding sites of α2u providing an acceptable dissociation constant indicating the binding efficiency of α2u. The obtained results are in corroboration with the data made through computational approach.
1. Methodology in structural determination and synthesis of insect pheromone
Directory of Open Access Journals (Sweden)
Guo-Qiang Lin
1991-01-01
Full Text Available By means of ethereal washing of insect pheromone glands of female moths, GC-MS detection along with microchemical reactions and electroantennogram (EAG survey, six economically important insect species were targeted for pheromone identification. The discovery of a natural pheromone inhibitor, chemo-selectivity and species isolation by pheromone will be described. The modified triple bond migration and triethylamine liganded vinyl cuprate were applied for achiral pheromone synthesis in double bond formation. Some optically active pheromones and their stereoisomers were synthesized through chiral pool or asymmetric synthesis. Some examples of chiral recognition of insects towards their chiral pheromones will be discussed. A CaH2 and silica gel catalyzed Sharpless Expoxidation Reaction was found in shortening the reaction time.
2. Enzymatic oxidations of alcohols in biosynthesis of bumblebee pheromones
OpenAIRE
2016-01-01
Secretion of cephalic labial gland of Buff-tailed bumblebee males (Bombus terrestris) contains a mixture of terpene alcohols, aliphatic alcohols, esters and alkanes with small amount of aldehydes potentially biosynthetized of (S)-2,3-dihydrofarnesol and geranylcitronellol (major alcoholic compounds). This secretion acts as a marking and luring pheromone during patrolling. This study is focused on oxidation of terpene alcohols using enzymes of cephalic labial gland of a bumblebee. In vitro inc...
3. Protein Folding and Aggregation into Amyloid: The Interference by Natural Phenolic Compounds
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Massimo Stefani
2013-06-01
Full Text Available Amyloid aggregation is a hallmark of several degenerative diseases affecting the brain or peripheral tissues, whose intermediates (oligomers, protofibrils and final mature fibrils display different toxicity. Consequently, compounds counteracting amyloid aggregation have been investigated for their ability (i to stabilize toxic amyloid precursors; (ii to prevent the growth of toxic oligomers or speed that of fibrils; (iii to inhibit fibril growth and deposition; (iv to disassemble preformed fibrils; and (v to favor amyloid clearance. Natural phenols, a wide panel of plant molecules, are one of the most actively investigated categories of potential amyloid inhibitors. They are considered responsible for the beneficial effects of several traditional diets being present in green tea, extra virgin olive oil, red wine, spices, berries and aromatic herbs. Accordingly, it has been proposed that some natural phenols could be exploited to prevent and to treat amyloid diseases, and recent studies have provided significant information on their ability to inhibit peptide/protein aggregation in various ways and to stimulate cell defenses, leading to identify shared or specific mechanisms. In the first part of this review, we will overview the significance and mechanisms of amyloid aggregation and aggregate toxicity; then, we will summarize the recent achievements on protection against amyloid diseases by many natural phenols.
4. A yeast pheromone-based inter-species communication system.
Science.gov (United States)
Hennig, Stefan; Clemens, André; Rödel, Gerhard; Ostermann, Kai
2015-02-01
We report on a pheromone-based inter-species communication system, allowing for a controlled cell-cell communication between the two species Saccharomyces cerevisiae and Schizosaccharomyces pombe as a proof of principle. It exploits the mating response pathways of the two yeast species employing the pheromones, α- or P-factor, as signaling molecules. The authentic and chimeric pheromone-encoding genes were engineered to code for the P-factor in S. cerevisiae and the α-factor in S. pombe. Upon transformation of the respective constructs, cells were enabled to express the mating pheromone of the opposite species. The supernatant of cultures of S. pombe cells expressing α-factor were able to induce a G1 arrest in the cell cycle, a change in morphology to the typical shmoo effect and expression driven by the pheromone-responsive FIG1 promoter in S. cerevisiae. The supernatant of cultures of S. cerevisiae cells expressing P-factor similarly induced cell cycle arrest in G1, an alteration in morphology typical for mating as well as the activation of the pheromone-responsive promoters of the rep1 and sxa2 genes in a pheromone-hypersensitive reporter strain of S. pombe. Apparently, both heterologous pheromones were correctly processed and secreted in an active form by the cells of the other species. Our data clearly show that the species-specific pheromone systems of yeast species can be exploited for a controlled inter-species communication.
5. Olfaction in the boll weevil,Anthonomus grandis Boh. (Coleoptera: Curculionidae): Electroantennogram studies.
Science.gov (United States)
Dickens, J C
1984-12-01
Electroantennogram (EAG) techniques were utilized to measure the antennal olfactory responsiveness of adult boll weevils,Anthonomus grandis Boh. (Coleoptera: Curculionidae), to 38 odorants, including both insect and host plant (Gossypium hirsutum L.) volatiles. EAGs of both sexes were indicative of at least two receptor populations: one receptor population primarily responsive to pheromone components and related compounds, the other receptor population primarily responsive to plant odors. Similar responses to male aggregation pheromone components (i.e., compounds I, II, and III + IV) were obtained from both sexes, but females were slightly more sensitive to I. Both sexes were highly responsive to components of the "green leaf volatile complex," especially the six-carbon saturated and monounsaturated primary alcohols. Heptanal was the most active aldehyde tested. More acceptors responded to oxygenated monoterpenes than to monoterpene hydrocarbons. β-Bisabolol, the major volatile of cotton, was the most active sesquiterpene. In general, males, which are responsible for host selection and pheromone production, were more sensitive to plant odors than were females. In fact, males were as sensitive to β-bisabolol and heptanal as to aggregation pheromone components. Electrophysiological data are discussed with regard to the role of insect and host plant volatiles in host selection and aggregation behavior of the boll weevil.
6. Conditional deletion of ERK5 MAP kinase in the nervous system impairs pheromone information processing and pheromone-evoked behaviors.
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Junhui Zou
Full Text Available ERK5 MAP kinase is highly expressed in the developing nervous system but absent in most regions of the adult brain. It has been implicated in regulating the development of the main olfactory bulb and in odor discrimination. However, whether it plays an essential role in pheromone-based behavior has not been established. Here we report that conditional deletion of the Mapk7 gene which encodes ERK5 in mice in neural stem cells impairs several pheromone-mediated behaviors including aggression and mating in male mice. These deficits were not caused by a reduction in the level of testosterone, by physical immobility, by heightened fear or anxiety, or by depression. Using mouse urine as a natural pheromone-containing solution, we provide evidence that the behavior impairment was associated with defects in the detection of closely related pheromones as well as with changes in their innate preference for pheromones related to sexual and reproductive activities. We conclude that expression of ERK5 during development is critical for pheromone response and associated animal behavior in adult mice.
7. Moths behaving like butterflies. Evolutionary loss of long range attractant pheromones in castniid moths: a Paysandisia archon model.
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Sarto i Monteys, Víctor; Acín, Patricia; Rosell, Glòria; Quero, Carmen; Jiménez, Miquel A; Guerrero, Angel
2012-01-01
In the course of evolution butterflies and moths developed two different reproductive behaviors. Whereas butterflies rely on visual stimuli for mate location, moths use the 'female calling plus male seduction' system, in which females release long-range sex pheromones to attract conspecific males. There are few exceptions from this pattern but in all cases known female moths possess sex pheromone glands which apparently have been lost in female butterflies. In the day-flying moth family Castniidae ("butterfly-moths"), which includes some important crop pests, no pheromones have been found so far. Using a multidisciplinary approach we described the steps involved in the courtship of P. archon, showing that visual cues are the only ones used for mate location; showed that the morphology and fine structure of the antennae of this moth are strikingly similar to those of butterflies, with male sensilla apparently not suited to detect female-released long range pheromones; showed that its females lack pheromone-producing glands, and identified three compounds as putative male sex pheromone (MSP) components of P. archon, released from the proximal halves of male forewings and hindwings. This study provides evidence for the first time in Lepidoptera that females of a moth do not produce any pheromone to attract males, and that mate location is achieved only visually by patrolling males, which may release a pheromone at short distance, putatively a mixture of Z,E-farnesal, E,E-farnesal, and (E,Z)-2,13-octadecadienol. The outlined behavior, long thought to be unique to butterflies, is likely to be widespread in Castniidae implying a novel, unparalleled butterfly-like reproductive behavior in moths. This will also have practical implications in applied entomology since it signifies that the monitoring/control of castniid pests should not be based on the use of female-produced pheromones, as it is usually done in many moths.
8. Pheromone communication in the fission yeast Schizosaccharomyces pombe
DEFF Research Database (Denmark)
Nielsen, O; Davey, William John; Nielsen, Olaf
1995-01-01
Conjugation between two haploid yeast cells is generally controlled by the reciprocal action of diffusible mating pheromones, cells of each mating type releasing pheromones that induce mating-specific changes in cells of the opposite type. Recent studies into pheromone signalling in the fission...
9. Pheromone reception in moths: from molecules to behaviors.
Science.gov (United States)
Zhang, Jin; Walker, William B; Wang, Guirong
2015-01-01
Male moths detect and find their mates using species-specific sex pheromones emitted by conspecific females. Olfaction plays a vital role in this behavior. Since the first discovery of an insect sex pheromone from the silkmoth Bombyx mori, great efforts have been spent on understanding the sensing of the pheromones in vivo. Much progress has been made in elucidating the molecular mechanisms that mediate chemoreception in insects in the past few decades. In this review, we focus on pheromone reception and detection in moths, from the molecular to the behavioral level. We trace the information pathway from the capture of pheromone by male antennae, binding and transportation to olfactory receptor neurons, receptor activation, signal transduction, molecule inactivation, through brain processing and behavioral response. We highlight the impact of recent studies and also provide our insights into pheromone processing. © 2015 Elsevier Inc. All rights reserved.
10. Alarm pheromone processing in the ant brain: an evolutionary perspective
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Makoto Mizunami
2010-06-01
Full Text Available Social insects exhibit sophisticated communication by means of pheromones, one example of which is the use of alarm pheromones to alert nestmates for colony defense. We review recent advances in the understanding of the processing of alarm pheromone information in the ant brain. We found that information about formic acid and n-undecane, alarm pheromone components, is processed in a set of specific glomeruli in the antennal lobe of the ant Camponotus obscuripes. Alarm pheromone information is then transmitted, via projection neurons, to the lateral horn and the calyces of the mushroom body of the protocerebrum. In the lateral horn, we found a specific area where terminal boutons of alarm pheromone-sensitive projection neurons are more densely distributed than in the rest of the lateral horn. Some neurons in the protocerebrum responded specifically to formic acid or n-undecane and they may participate in the control of behavioral responses to each pheromone component. Other neurons, especially those originating from the mushroom body lobe, responded also to non-pheromonal odors and may play roles in integration of pheromonal and non-pheromonal signals. We found that a class of neurons receive inputs in the lateral horn and the mushroom body lobe and terminate in a variety of premotor areas. These neurons may participate in the control of aggressive behavior, which is sensitized by alarm pheromones and is triggered by non-pheromonal sensory stimuli associated with a potential enemy. We propose that the alarm pheromone processing system has evolved by differentiation of a part of general odor processing system.
11. RNA interference of pheromone biosynthesis-activating neuropeptide receptor suppresses mating behavior by inhibiting sex pheromone production in Plutella xylostella (L.).
Science.gov (United States)
Lee, Dae-Weon; Shrestha, Sony; Kim, A Young; Park, Seok Joo; Yang, Chang Yeol; Kim, Yonggyun; Koh, Young Ho
2011-04-01
Sex pheromone production is regulated by pheromone biosynthesis-activating neuropeptide (PBAN) in many lepidopteran species. We cloned a PBAN receptor (Plx-PBANr) gene from the female pheromone gland of the diamondback moth, Plutella xylostella (L.). Plx-PBANr encodes 338 amino acids and has conserved structural motifs implicating in promoting G protein coupling and tyrosine-based sorting signaling along with seven transmembrane domains, indicating a typical G protein-coupled receptor. The expression of Plx-PBANr was found only in the pheromone gland of female adults among examined tissues and developmental stages. Heterologous expression in human uterus cervical cancer cells revealed that Plx-PBANr induced significant calcium elevation when challenged with Plx-PBAN. Female P. xylostella injected with double-stranded RNA specific to Plx-PBANr showed suppression of the receptor gene expression and exhibited significant reduction in pheromone biosynthesis, which resulted in loss of male attractiveness. Taken together, the identified PBAN receptor is functional in PBAN signaling via calcium secondary messenger, which leads to activation of pheromone biosynthesis and male attraction. Copyright © 2011 Elsevier Ltd. All rights reserved.
12. Nutrient-dependent/pheromone-controlled adaptive evolution: a model
Directory of Open Access Journals (Sweden)
James Vaughn Kohl
2013-06-01
Full Text Available Background: The prenatal migration of gonadotropin-releasing hormone (GnRH neurosecretory neurons allows nutrients and human pheromones to alter GnRH pulsatility, which modulates the concurrent maturation of the neuroendocrine, reproductive, and central nervous systems, thus influencing the development of ingestive behavior, reproductive sexual behavior, and other behaviors. Methods: This model details how chemical ecology drives adaptive evolution via: (1 ecological niche construction, (2 social niche construction, (3 neurogenic niche construction, and (4 socio-cognitive niche construction. This model exemplifies the epigenetic effects of olfactory/pheromonal conditioning, which alters genetically predisposed, nutrient-dependent, hormone-driven mammalian behavior and choices for pheromones that control reproduction via their effects on luteinizing hormone (LH and systems biology. Results: Nutrients are metabolized to pheromones that condition behavior in the same way that food odors condition behavior associated with food preferences. The epigenetic effects of olfactory/pheromonal input calibrate and standardize molecular mechanisms for genetically predisposed receptor-mediated changes in intracellular signaling and stochastic gene expression in GnRH neurosecretory neurons of brain tissue. For example, glucose and pheromones alter the hypothalamic secretion of GnRH and LH. A form of GnRH associated with sexual orientation in yeasts links control of the feedback loops and developmental processes required for nutrient acquisition, movement, reproduction, and the diversification of species from microbes to man. Conclusion: An environmental drive evolved from that of nutrient ingestion in unicellular organisms to that of pheromone-controlled socialization in insects. In mammals, food odors and pheromones cause changes in hormones such as LH, which has developmental affects on pheromone-controlled sexual behavior in nutrient-dependent reproductively
13. Pheromone-based disruption of Eucosma sonomana and Rhyacionia zozana (Lepidoptera: Tortricidae) using aerially applied microencapsulated pheromone
Science.gov (United States)
Nancy E. Gillette; John D. Stein; Donald R. Owen; Jeffrey N. Webster; Sylvia R. Mori
2006-01-01
Two aerial applications of microencapsulated pheromone were conducted on five 20.2 ha plots to disrupt western pine shoot borer (Eucosma sonomana Kearfott) and ponderosa pine tip moth (Rhyacionia zowna (Kearfott): Lepidoptera: Tortricidae) orientation to pheromones and oviposition in ponderosa pine plantations in 2002 and 2004...
14. Characterization of E and Z isomers in macrocyclic lactones and acyclic pheromones by NMR spectra
International Nuclear Information System (INIS)
Mahajan, J.R.; Resck, I.S.; Braz Filho, R.; Carvalho, M.G. de
1995-01-01
A large proportion of pheromones, isolated from a variety of insects, constitutes a big list of diversely functionalized acyclic compounds, which have been synthesized by several routes. Catalytic or chemical methods were examined for the Z to E isomerization and their efficiency checked by 1 H and 13 C NMR spectra. Nuclear magnetic resonance has been used to identify and characterize molecular structure of the compounds, besides chemical shifts was analysed
15. Pheromone Static Routing Strategy for Complex Networks
Science.gov (United States)
Hu, Mao-Bin; Henry, Y. K. Lau; Ling, Xiang; Jiang, Rui
2012-12-01
We adopt the concept of using pheromones to generate a set of static paths that can reach the performance of global dynamic routing strategy [Phys. Rev. E 81 (2010) 016113]. The path generation method consists of two stages. In the first stage, a pheromone is dropped to the nodes by packets forwarded according to the global dynamic routing strategy. In the second stage, pheromone static paths are generated according to the pheromone density. The output paths can greatly improve traffic systems' overall capacity on different network structures, including scale-free networks, small-world networks and random graphs. Because the paths are static, the system needs much less computational resources than the global dynamic routing strategy.
16. Semiochemicals to enhance herbivory by Diorhabda carinulata aggregations in saltcedar (Tamarix spp.) infestations
Science.gov (United States)
Alexander M. Gaffke; Sharlene E. Sing; Tom L. Dudley; Daniel W. Bean; Justin A. Russak; Agenor Mafra-Neto; Paul A. Grieco; Robert K. D. Peterson; David K. Weaver
2018-01-01
BACKGROUND: Semiochemicals formonitoring, attracting or repelling pest and beneficial organisms are increasingly deployed in agricultural and forest systems for pest management. However, the use of aggregation pheromones and host-plant attractants for the express purpose of increasing the efficacy of classical biological control agents of weeds has not been widely...
17. A Predictive Model for Yeast Cell Polarization in Pheromone Gradients.
Science.gov (United States)
Muller, Nicolas; Piel, Matthieu; Calvez, Vincent; Voituriez, Raphaël; Gonçalves-Sá, Joana; Guo, Chin-Lin; Jiang, Xingyu; Murray, Andrew; Meunier, Nicolas
2016-04-01
Budding yeast cells exist in two mating types, a and α, which use peptide pheromones to communicate with each other during mating. Mating depends on the ability of cells to polarize up pheromone gradients, but cells also respond to spatially uniform fields of pheromone by polarizing along a single axis. We used quantitative measurements of the response of a cells to α-factor to produce a predictive model of yeast polarization towards a pheromone gradient. We found that cells make a sharp transition between budding cycles and mating induced polarization and that they detect pheromone gradients accurately only over a narrow range of pheromone concentrations corresponding to this transition. We fit all the parameters of the mathematical model by using quantitative data on spontaneous polarization in uniform pheromone concentration. Once these parameters have been computed, and without any further fit, our model quantitatively predicts the yeast cell response to pheromone gradient providing an important step toward understanding how cells communicate with each other.
18. Heritable variation of sex pheromone composition and the potential for evolution of resistance to pheromone-based control of the Indian meal moth, Plodia interpunctella.
Science.gov (United States)
Svensson, Glenn P; Ryne, Camilla; Löfstedt, Christer
2002-07-01
The short-term evolutionary effect of pheromone-based mating disruption on the mating ability of the Indian meal moth, Plodia interpunctella, was investigated. Three independent selection lines were established, and the mating ability of moths in plastic tents treated with high doses of pheromone and in control tents was compared for two consecutive generations. In addition, the heritability of the sex pheromone blend, measured as the ratio of two major pheromone components (Z,E)-9,12-tetradecadienyl acetate and (Z,E)-9,12-tetradecadienol, was estimated. Based on a mother-daughter regression analysis including 21 families, the heritability of the pheromone blend was 0.65 +/- 0.14, indicating a potential for evolutionary change of the character. However, no increase in mating ability of females in pheromone-treated tents or alteration of the pheromone blend was observed in any selection line when compared with control lines, indicating no or weak selection on the pheromone blend as well as other traits influencing mating ability of this species under the created mating disruption conditions. Factors contributing to the lack of selection effects are discussed.
19. Ratiometric Decoding of Pheromones for a Biomimetic Infochemical Communication System
Directory of Open Access Journals (Sweden)
Guangfen Wei
2017-10-01
Full Text Available Biosynthetic infochemical communication is an emerging scientific field employing molecular compounds for information transmission, labelling, and biochemical interfacing; having potential application in diverse areas ranging from pest management to group coordination of swarming robots. Our communication system comprises a chemoemitter module that encodes information by producing volatile pheromone components and a chemoreceiver module that decodes the transmitted ratiometric information via polymer-coated piezoelectric Surface Acoustic Wave Resonator (SAWR sensors. The inspiration for such a system is based on the pheromone-based communication between insects. Ten features are extracted from the SAWR sensor response and analysed using multi-variate classification techniques, i.e., Linear Discriminant Analysis (LDA, Probabilistic Neural Network (PNN, and Multilayer Perception Neural Network (MLPNN methods, and an optimal feature subset is identified. A combination of steady state and transient features of the sensor signals showed superior performances with LDA and MLPNN. Although MLPNN gave excellent results reaching 100% recognition rate at 400 s, over all time stations PNN gave the best performance based on an expanded data-set with adjacent neighbours. In this case, 100% of the pheromone mixtures were successfully identified just 200 s after they were first injected into the wind tunnel. We believe that this approach can be used for future chemical communication employing simple mixtures of airborne molecules.
20. Pest repellent properties of ant pheromones
DEFF Research Database (Denmark)
Offenberg, Joachim
2012-01-01
of ant pheromones may be sufficient to repel pest insects from ant territories. The study of ant semiochemicals is in its infancy, yet, evidence for their potential use in pest management is starting to build up. Pheromones from four of five tested ant species have been shown to deter herbivorous insect...... prey and competing ant species are also deterred by ant deposits, whereas ant symbionts may be attracted to them. Based on these promising initial findings, it seems advisable to further elucidate the signaling properties of ant pheromones and to test and develop their use in future pest management....
1. Identification of volatile sex pheromone components released by the southern armyworm,Spodoptera eridania (Cramer).
Science.gov (United States)
Teal, P E; Mitchell, E R; Tumlinson, J H; Heath, R R; Sugie, H
1985-06-01
2. Captura de Rhynchophorus palmarum L. (Coleoptera: curculionidae em armadilhas iscadas com o feromônio de agregação e compostos voláteis de frutos do abacaxi Trap catches of Rhynchophorus palmarum L. (Coleoptera: curculionidae baited with its aggregation pheromone and volatile compounds from pineapple
Directory of Open Access Journals (Sweden)
2003-04-01
3. Olfactory responses of Plutella xylostella natural enemies to host pheromone, larval frass, and green leaf cabbage volatiles.
Science.gov (United States)
Reddy, G V P; Holopainen, J K; Guerrero, A
2002-01-01
The parasitoids Trichogramma chilonis (Hymenoptera: Trichogrammatidae) and Cotesia plutellae (Hymenoptera: Braconidae), and the predator Chrysoperla carnea (Neuroptera: Chrysopidae), are potential biological control agents for the diamondback moth, Plutella xylostella (Lepidoptera: Yponomeutidae). We present studies on the interactions between these bioagents and various host-associated volatiles using a Y olfactometer. T chilonis was attracted to a synthetic pheromone blend (Z11-16:Ald, Z11-16:Ac, and Z11-16:OH in a 1:1:0.01 ratio), to Z11-16:Ac alone, and to a 1:1 blend of Z11-16:Ac and Z11-16:Ald. C. plutellae responded to the blend and to Z11-16:Ac and Z11-16:Ald. Male and female C. carnea responded to the blend and to a 1:1 blend of the major components of the pheromone, although no response was elicited by single compounds. Among the four host larval frass volatiles tested (dipropyl disulfide, dimethyl disulfide, allyl isothiocyanate, and dimethyl trisulfide), only allyl isothiocyanate elicited significant responses in the parasitoids and predator, but C. plutellae and both sexes of C. carnea did respond to all four volatiles. Among the green leaf volatiles of cabbage (Brassica oleracea subsp. capitata), only Z3-6:Ac elicited significant responses from T. chilonis, C. plutellae, and C. carnea, but C. plutellae also responded to E2-6:Ald and Z3-6:OH. When these volatiles were blended with the pheromone, the responses were similar to those elicited by the pheromone alone, except for C. carnea males, which had an increased response. The effect of temperature on the response of the biological agents to a mixture of the pheromone blend and Z3-6:Ac was also studied. T. chilonis was attracted at temperatures of 25-35 degrees C, while C. plutellae and C. carnea responded optimally at 30-35 degrees C and 20-25 degrees C, respectively. These results indicate that the sex pheromone and larval frass volatiles from the diamondback moth, as well as volatile compounds from
4. Two odorant-binding proteins mediate the behavioural response of aphids to the alarm pheromone (E-ß-farnesene and structural analogues.
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Yu Feng Sun
Full Text Available Aphids are agricultural pests of great economical interest. Alternatives to insecticides, using semiochemicals, are of difficult applications. In fact, sex pheromones are of little use as aphids reproduce partenogenetically most of the time. Besides, the alarm pheromone, (E-ß-farnesene for a great number of species, is difficult to synthesize and unstable in the environment. The search for novel semiochemicals to be used in population control can be efficiently approached through the study of the olfactory system at the biochemical level. Recently odorant-binding proteins (OBPs have been shown to play a central role in olfactory recognition, thus becoming the target of choice for designing new semiochemicals.To address the question of how the alarm message is recognised at the level of OBPs, we have tested 29 compounds, including (E-ß-farnesene, in binding assays with 6 recombinant proteins and in behaviour experiments. We have found that good repellents bind OBP3 and/or OBP7, while non repellents present different spectra of binding. These results have been verified with two species of aphids, Acyrthosiphon pisum and Myzus persicae, both using (E-ß-farnesene as the alarm pheromone.Our results represent further support to the idea (so far convincingly demonstrated only in Drosophila that OBPs are involved in decoding the chemical information of odorants and pheromones, and for the first time provide such evidence in other insect species and using wild-type insects. Moreover, the data offer guidelines and protocols for the discovery of potential alarm pheromones, using ligand-binding assays as a preliminary screening before subjecting selected compounds to behaviour tests.
5. Collection of pheromone from atmosphere surrounding boll weevils,Anthonomus grandis.
Science.gov (United States)
Chang, J F; Benedict, J H; Payne, T L; Camp, B J; Vinson, S B
1989-02-01
An effluvial method was developed to collect the pheromone, grandlure from actively calling male boll weevils,Anthonomus grandis Boheman. The adsorbant, Porapak Q (ethylvinylbenzene-divinylbenzene), was utilized to trap and concentrate the pheromone. Captured pheromone was desorbed from columns packed with Porapak Q by elution withn-pentane and quantified by capillary column gas-liquid chromatography. In recovery studies with known amounts of synthetic grandlure, we found that the amount of each pheromone component collected was a function of collection duration, elution volume, and initial concentration. This effluvial method was capable of recovering as much as 94.9% of a known quantity (80 μg) of grandlure. The chromatograms were free of extraneous peaks. In studies of insect-produced pheromone, the effluvial method was used to collect pheromone from the air space surrounding male boll weevils as they fed on flower buds from CAMD-E cotton. The quantity and quality of boll-weevil-produced pheromone was determined for days 6, 8, 10, 11, 12, 13, and 14 of boll weevil adulthood. The maximum quantity of natural pheromone was produced on day 13 (4.2 μg/weevil) with a pheromone component ratio of 2.41∶2.29∶0.95∶1 for components I, II, III, and IV, respectively. The effluvial method described in this report is an efficient method to collect and quantify boll weevil pheromone from the atmosphere surrounding actively calling insects. Other applications of this method are suggested.
6. Controlled release of insect sex pheromones from paraffin wax and emulsions.
Science.gov (United States)
Atterholt, C A; Delwiche, M J; Rice, R E; Krochta, J M
1999-02-22
Paraffin wax and aqueous paraffin emulsions can be used as controlled release carriers for insect sex pheromones for mating disruption of orchard pests. Paraffin can be applied at ambient temperature as an aqueous emulsion, adheres to tree bark or foliage, releases pheromone for an extended period of time, and will slowly erode from bark and biodegrade in soil. Pheromone emulsions can be applied with simple spray equipment. Pheromone release-rates from paraffin were measured in laboratory flow-cell experiments. Pheromone was trapped from an air stream with an adsorbent, eluted periodically, and quantified by gas chromatography. Pheromone release from paraffin was partition-controlled, providing a constant (zero-order) release rate. A typical paraffin emulsion consisted of 30% paraffin, 4% pheromone, 4% soy oil, 1% vitamin E, 2% emulsifier, and the balance water. Soy oil and vitamin E acted as volatility suppressants. A constant release of oriental fruit moth pheromone from paraffin emulsions was observed in the laboratory for more than 100 days at 27 degreesC, with release-rates ranging from 0.4 to 2 mg/day, depending on the concentration and surface area of the dried emulsion. The use of paraffin emulsions is a viable method for direct application of insect pheromones for mating disruption. Sprayable formulations can be designed to release insect pheromones to the environment at a rate necessary for insect control by mating disruption. At temperatures below 38 degreesC, zero-order release was observed. At 38 degreesC and higher, pheromone oxidation occurred. A partition-controlled release mechanism was supported by a zero-order pheromone release-rate, low air/wax partition coefficients, and pheromone solubility in paraffin.
7. Pheromone communication in amphibians and reptiles.
Science.gov (United States)
Houck, Lynne D
2009-01-01
This selective review considers herpetological papers that feature the use of chemical cues, particularly pheromones involved in reproductive interactions between potential mates. Primary examples include garter snake females that attract males, lacertid lizards and the effects of their femoral gland secretions, aquatic male newts that chemically attract females, and terrestrial salamander males that chemically persuade a female to mate. Each case study spans a number of research approaches (molecular, biochemical, behavioral) and is related to sensory processing and the physiological effects of pheromone delivery. These and related studies show that natural pheromones can be identified, validated with behavioral tests, and incorporated in research on vomeronasal functional response.
8. Novel, male-produced aggregation pheromone of the cerambycid beetle Rosalia alpina, a priority species of European conservation concern
Czech Academy of Sciences Publication Activity Database
Žunič Kosi, A.; Zou, Y.; Hoskovec, Michal; Vrezec, A.; Stritih, N.; Millar, J. G.
2017-01-01
Roč. 12, č. 8 (2017), č. článku e0183279. E-ISSN 1932-6203 Institutional support: RVO:61388963 Keywords : 1758 Coleoptera Cerambycidae * host plant volatiles * sex pheromone Subject RIV: CC - Organic Chemistry OBOR OECD: Organic chemistry Impact factor: 2.806, year: 2016 http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0183279
9. Intercellular signaling in Stigmatella aurantiaca: purification and characterization of stigmolone, a myxobacterial pheromone.
Science.gov (United States)
Plaga, W; Stamm, I; Schairer, H U
1998-09-15
The myxobacterium Stigmatella aurantiaca passes through a life cycle that involves formation of a multicellular fruiting body as the most complex stage. An early step in this differentiation process depends on a signal factor secreted by the cells when nutrients become limited. The formation of a fruiting body from a small cell population can be accelerated by addition of this secreted material. The bioactive compound was found to be steam volatile. It was purified to homogeneity by steam distillation followed by reversed-phase and normal-phase HPLC. The pheromone was named stigmolone, in accordance with the structure 2,5, 8-trimethyl-8-hydroxy-nonan-4-one, as determined by NMR and mass spectrometry. Stigmolone represents a structurally unique and highly bioactive prokaryotic pheromone that is effective in the bioassay at 1 nM concentration.
10. General odorant-binding proteins and sex pheromone guide larvae of Plutella xylostella to better food.
Science.gov (United States)
Zhu, Jiao; Ban, Liping; Song, Li-Mei; Liu, Yang; Pelosi, Paolo; Wang, Guirong
2016-05-01
Olfaction of Lepidopteran larvae has received little attention, compared to the damage to crops done by insects at this stage. We report that larvae of the diamondback moth Plutella xylostella are attracted to their natural sex pheromone and to their major component (Z)-11-hexadecenal, but only in a food context. For such task they use two general odorant-binding proteins (GOBPs), abundantly expressed in the three major sensilla basiconica of the larval antenna, as shown by whole-mount immunostaining and immunocytochemistry experiments. None of the three genes encoding pheromone-binding proteins (PBPs) are expressed at this stage. Both recombinant GOBPs bind (Z)-11-hexadecenal and the corresponding alcohol, but not the acetate. Binding experiments performed with five mutants of GOBP2, where aromatic residues in the binding pocket were replaced with leucine showed that only one or two amino acid substitutions can completely abolish binding to the pheromone shifting the affinity to plant-derived compounds. We hypothesise that detection of their species-specific pheromone may direct larvae to the sites of foraging chosen by their mother when laying eggs, to find better food, as well as to reduce competition with individuals of the same or other species sharing the same host plant. We also provide evidence that GOBP2 is a narrowly tuned binding protein, whose affinity can be easily switched from linear pheromones to branched plants terpenoids, representing a tool better suited for the simple olfactory system of larvae, as compared to the more sophisticated organ of adults. Copyright © 2016 Elsevier Ltd. All rights reserved.
11. Functionality of the Paracoccidioides mating α-pheromone-receptor system.
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Jéssica A Gomes-Rezende
Full Text Available Recent evidence suggests that Paracoccidioides species have the potential to undergo sexual reproduction, although no sexual cycle has been identified either in nature or under laboratory conditions. In the present work we detected low expression levels of the heterothallic MAT loci genes MAT1-1 and MAT1-2, the α-pheromone (PBα gene, and the α- and a-pheromone receptor (PREB and PREA genes in yeast and mycelia forms of several Paracoccidioides isolates. None of the genes were expressed in a mating type dependent manner. Stimulation of P. brasiliensis MAT1-2 strains with the synthetic α-pheromone peptide failed to elicit transcriptional activation of MAT1-2, PREB or STE12, suggesting that the strains tested are insensitive to α-pheromone. In order to further evaluate the biological functionality of the pair α-pheromone and its receptor, we took advantage of the heterologous expression of these Paracoccidioides genes in the corresponding S. cerevisiae null mutants. We show that S. cerevisiae strains heterologously expressing PREB respond to Pbα pheromone either isolated from Paracoccidioides culture supernatants or in its synthetic form, both by shmoo formation and by growth and cell cycle arrests. This allowed us to conclude that Paracoccidioides species secrete an active α-pheromone into the culture medium that is able to activate its cognate receptor. Moreover, expression of PREB or PBα in the corresponding null mutants of S. cerevisiae restored mating in these non-fertile strains. Taken together, our data demonstrate pheromone signaling activation by the Paracoccidioides α-pheromone through its receptor in this yeast model, which provides novel evidence for the existence of a functional mating signaling system in Paracoccidioides.
12. Genomewide identification of pheromone-targeted transcription in fission yeast
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Wright Anthony
2006-11-01
Full Text Available Abstract Background Fission yeast cells undergo sexual differentiation in response to nitrogen starvation. In this process haploid M and P cells first mate to form diploid zygotes, which then enter meiosis and sporulate. Prior to mating, M and P cells communicate with diffusible mating pheromones that activate a signal transduction pathway in the opposite cell type. The pheromone signalling orchestrates mating and is also required for entry into meiosis. Results Here we use DNA microarrays to identify genes that are induced by M-factor in P cells and by P-factor in M-cells. The use of a cyr1 genetic background allowed us to study pheromone signalling independently of nitrogen starvation. We identified a total of 163 genes that were consistently induced more than two-fold by pheromone stimulation. Gene disruption experiments demonstrated the involvement of newly discovered pheromone-induced genes in the differentiation process. We have mapped Gene Ontology (GO categories specifically associated with pheromone induction. A direct comparison of the M- and P-factor induced expression pattern allowed us to identify cell-type specific transcripts, including three new M-specific genes and one new P-specific gene. Conclusion We found that the pheromone response was very similar in M and P cells. Surprisingly, pheromone control extended to genes fulfilling their function well beyond the point of entry into meiosis, including numerous genes required for meiotic recombination. Our results suggest that the Ste11 transcription factor is responsible for the majority of pheromone-induced transcription. Finally, most cell-type specific genes now appear to be identified in fission yeast.
13. Putative pathway of sex pheromone biosynthesis and degradation by expression patterns of genes identified from female pheromone gland and adult antenna of Sesamia inferens (Walker).
Science.gov (United States)
Zhang, Ya-Nan; Xia, Yi-Han; Zhu, Jia-Yao; Li, Sheng-Yun; Dong, Shuang-Lin
2014-05-01
The general pathway of biosynthesis and degradation for Type-I sex pheromones in moths is well established, but some genes involved in this pathway remain to be characterized. The purple stem borer, Sesamia inferens, employs a pheromone blend containing components with three different terminal functional groups (Z11-16:OAc, Z11-16:OH, and Z11-16:Ald) of Type-I sex pheromones. Thus, it provides a good model to study the diversity of genes involved in pheromone biosynthesis and degradation pathways. By analyzing previously obtained transcriptomic data of the sex pheromone glands and antennae, we identified 73 novel genes that are possibly related to pheromone biosynthesis (46 genes) or degradation (27 genes). Gene expression patterns and phylogenetic analysis revealed that one desaturase (SinfDes4), one fatty acid reductase (SinfFAR2), and one fatty acid xtransport protein (SinfFATP1) genes were predominantly expressed in pheromone glands, and clustered with genes involved in pheromone synthesis in other moth species. Ten genes including five carboxylesterases (SinfCXE10, 13, 14, 18, and 20), three aldehyde oxidases (SinfAOX1, 2 and 3), and two alcohol dehydrogenases (SinfAD1 and 3) were expressed specifically or predominantly in antennae, and could be candidate genes involved in pheromone degradation. SinfAD1 and 3 are the first reported alcohol dehydrogenase genes with antennae-biased expression. Based on these results we propose a pathway involving these potential enzyme-encoding gene candidates in sex pheromone biosynthesis and degradation in S. inferens. This study provides robust background information for further elucidation of the genetic basis of sex pheromone biosynthesis and degradation, and ultimately provides potential targets to disrupt sexual communication in S. inferens for control purposes.
14. Pest repelling properties of ant pheromones
DEFF Research Database (Denmark)
Offenberg, Joachim
2014-01-01
Ants control pests via predation and physical deterrence; however, ant communication is based on chemical cues which may serve as warning signals to potential prey and other intruders. The presence of ant pheromones may, thus, be sufficient to repel pests from ant territories. This mini-review sh......-review shows that four out of five tested ant species deposit pheromones that repel herbivorous prey from their host plants.......Ants control pests via predation and physical deterrence; however, ant communication is based on chemical cues which may serve as warning signals to potential prey and other intruders. The presence of ant pheromones may, thus, be sufficient to repel pests from ant territories. This mini...
15. Characteristic odor of Osmoderma eremita identified as a male-released pheromone.
Science.gov (United States)
Larsson, Mattias C; Hedin, Jonas; Svensson, Glenn P; Tolasch, Till; Francke, Wittko
2003-03-01
Osmoderma eremita (Scopoli) is an endangered scarab beetle living in hollow trees. It has mainly been known for its characteristic odor, typically described as a fruity, peachlike or plumlike aroma. The odor emanating from a single beetle can sometimes be perceived from a distance of several meters. In this paper, we show that the characteristic odor from O. eremita is caused by the compound (R)-(+)-gamma-decalactone, released in large quantities mainly or exclusively by male beetles. Antennae from male and female beetles responded in a similar way to (R)-(+)-gamma-decalactone in electroantennographic recordings. Field trapping experiments showed that (R)-(+)-gamma-decalactone is a pheromone attracting female beetles. Lactones similar to (R)-(+)-gamma-decalactone are frequently used as female-released sex pheromones by phytophagous scarabs. This is, however, the first evidence of a lactone used as a male-produced pheromone in scarab beetles. We propose that the strong signal from males is a sexually selected trait used to compete for females and matings. The signal could work within trees but also act as a guide to tree hollows, which are an essential resource for O. eremita. Males may, thus, attract females dispersing from their natal tree by advertising a suitable habitat. This signal could also be exploited by other males searching for tree hollows or for females, which would explain the catch of several males in our traps.
16. With or without pheromone habituation: possible differences between insect orders?
Science.gov (United States)
Suckling, David Maxwell; Stringer, Lloyd D; Jiménez-Pérez, Alfredo; Walter, Gimme H; Sullivan, Nicola; El-Sayed, Ashraf M
2018-06-01
Habituation to sex pheromones is one of the key mechanisms in mating disruption, an insect control tactic. Male moths often show reduced sexual response after pre-exposure to female sex pheromone. Mating disruption is relatively rare in insect orders other than Lepidoptera. As a positive control we confirmed habituation in a moth (Epiphyas postvittana) using 24 h pre-exposure to sex pheromone to reduce subsequent activation behaviour. We then tested the impact of pre-exposure to sex or trail pheromone on subsequent behavioural response with insects from three other orders. Similar pre-exposure for 24 h to either sex pheromone [Pseudococcus calceolariae (Homoptera) and apple leaf curling midge Dasineura mali (Diptera), or trail pheromone of Argentine ants (Linepithema humile (Hymenoptera)], followed by behavioural assay in clean air provided no evidence of habituation after pre-exposure in these latter cases. The moths alone were affected by pre-exposure to pheromone. For pests without habituation, sustained attraction to a point source may make lure and kill more economical. Improved knowledge of behavioural processes should lead to better success in pest management and mechanisms should be investigated further to inform studies and practical efforts generally enhancing effectiveness of pheromone-based management. © 2017 Society of Chemical Industry. © 2017 Society of Chemical Industry.
17. Pheromone use for insect control: present status and prospect in Bangladesh
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Md. Azharul Islam
2012-06-01
Full Text Available The insect’s world is filled with many odors. Insects use these odors to cue them in a variety of complex social behaviors, including courtship, mating, and egg laying. Scientists and pest control specialists have known about these complex communication systems for decades. The main aim of this study was to visualize the availability, trends and differences in the sources of pheromone control in agricultural growth of Bangladesh. It also concerned on constrains and present use of pheromone and their possible recommendation on behalf of Bangladesh agriculture. It concentrated on the data during last three decades (1980-2010, comprising status of pheromone use in Bangladesh agriculture and its future. Review revealed that Bangladesh has been enormously successful in increasing pheromone use in agricultural production (especially for vegetables. Understanding of the nature of pheromones and their potential for pest control along with the future prospective of pheromone technique in agriculture were stated. Since the pheromone, technologies for control of major crop pests in Bangladesh are still limited. So that this review emphasized on more attention to the authority to increase the research works and project facilities related to develop and promote pheromone techniques. It is highly recommended to increase availability of pheromone in market, more investment in research and development, introduction of newly identified pheromone for specific pest, to assist government and non-government organizations to work with farmers to reduce harmful insecticide use and promote pheromone tactics as one part of integrated crop management (ICM.
18. Steel slag aggregate in concrete: the effect of ageing on potentially expansive compounds
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Frías, M.
2010-02-01
Full Text Available Growing numbers of plants have sprung up in recent years to treat the electric arc furnace slag generated in scrap metal melting. When this by-product is separated, crushed and screened, it yields a granular material known as steel slag aggregate, which may be profitably used in the manufacture of commercial concrete. The feasibility of this application depends essentially on the volume stability of the resulting aggregate. The present paper discusses the potentially expansive compounds (Cl-, SO3, free CaO and free MgO present in aggregate derived from different types of black slag during aggregate ageing. The aim is to establish optimal ageing conditions to ensure volume stability in steel slag aggregate. The findings showed that the slag analyzed had low concentrations of the expansive compounds studied and that possible swelling can be reduced by 45day ageing.
En los últimos años están surgiendo diferentes plantas de tratamiento de las escorias generadas en el proceso de fusión de la chatarra en los hornos de arco eléctrico. Mediante procesos de separación, machaqueo y cribado se obtiene un material granular denominado árido siderúrgico, que puede ser atractivo para su utilización en la fabricación de hormigones comerciales. En este sentido, la viabilidad de dicha aplicación dependerá, fundamentalmente, de asegurar su estabilidad en volumen. Este trabajo presenta un estudio de los compuestos potencialmente expansivos (Cl-, SO3, CaO libre y MgO libre de los áridos siderúrgicos procedentes de diferentes tipos de escorias negras, así como su evolución después de un proceso de envejecimiento. El objetivo es establecer las condiciones óptimas de un proceso de envejecimiento a partir del cual se pueda asegurar la estabilidad, en volumen, del árido siderúrgico. Los resultados evidencian que las escorias analizadas tienen bajas concentraciones de los compuestos expansivos
19. A contact sex pheromone component of the emerald ash borer Agrilus planipennis Fairmaire (Coleoptera: Buprestidae).
Science.gov (United States)
Silk, Peter J; Ryall, Krista; Barry Lyons, D; Sweeney, Jon; Wu, Junping
2009-05-01
Analyses of the elytral hydrocarbons from male and female emerald ash borer, Agrilus planipennis Fairmaire, that were freshly emerged vs. sexually mature (>10 days old) revealed a female-specific compound, 9-methyl-pentacosane (9-Me-C(25)), only present in sexually mature females. This material was synthesized by the Wittig reaction of 2-decanone with (n-hexadecyl)-triphenylphosphonium bromide followed by catalytic reduction to yield racemic 9-Me C(25), which matched the natural compound by gas chromatography/mass spectrometry (retention time and EI mass spectrum). In field bioassays with freeze-killed sexually mature A. planipennis females, feral males spent significantly more time in contact and attempting copulation with unwashed females than with females that had been washed in n-hexane to remove the cuticular lipids. Hexane-washed females to which 9-Me-C(25) had been reapplied elicited similar contact time and percentage of time attempting copulation as unwashed females, indicating that 9-methyl-pentacosane is a contact sex pheromone component of A. planipennis. This is the first contact sex pheromone identified in the Buprestidae.
20. Pheromones cause disease: the exocrinology of anorexia nervosa.
Science.gov (United States)
Nicholson, B
2000-03-01
The aetiology of anorexia nervosa is exocrinological. This notion is supported by physical evidence in animal models with directly comparable symptomatology. Anorexia nervosa (AN) syndrome would be a puberty delay caused by reception and autoreception of conspecific pheromone emissions: a pheromone-induced puberty delay (PIPD). As such, it would be amenable to medical treatment drawing from forty years of research in animals. This hypothesis is testable. For instance, since food ad libitum is a prerequisite for PIPD, occasional supervised fasting in healthy peripuberal subjects should prevent AN. Besides, tolerating an untestable thought disease (1,2) with symptoms of a curable well-understood animal condition would be anti-scientific and perpetuates medical disaster. Even their endocrinologies are identical. Pheromone feedback tunes animal appetites and immunity to available resources and prospects. In addition to timing puberty, pheromones regulate fertility. Pheromones will probably be implicated in the aetiology of the psychiatric and autoimmune diseases. This is the second in a series of twelve papers to explore this contention systematically. (c) 2000 Harcourt Publishers Ltd Copyright 2000 Harcourt Publishers Ltd.
1. The Dynamics of Pheromone Gland Synthesis and Release: a Paradigm Shift for Understanding Sex Pheromone Quantity in Female Moths.
Science.gov (United States)
Foster, Stephen P; Anderson, Karin G; Casas, Jérôme
2018-05-10
Moths are exemplars of chemical communication, especially with regard to specificity and the minute amounts they use. Yet, little is known about how females manage synthesis and storage of pheromone to maintain release rates attractive to conspecific males and why such small amounts are used. We developed, for the first time, a quantitative model, based on an extensive empirical data set, describing the dynamical relationship among synthesis, storage (titer) and release of pheromone over time in a moth (Heliothis virescens). The model is compartmental, with one major state variable (titer), one time-varying (synthesis), and two constant (catabolism and release) rates. The model was a good fit, suggesting it accounted for the major processes. Overall, we found the relatively small amounts of pheromone stored and released were largely a function of high catabolism rather than a low rate of synthesis. A paradigm shift may be necessary to understand the low amounts released by female moths, away from the small quantities synthesized to the (relatively) large amounts catabolized. Future research on pheromone quantity should focus on structural and physicochemical processes that limit storage and release rate quantities. To our knowledge, this is the first time that pheromone gland function has been modeled for any animal.
2. Gonadotropin-Releasing Hormone Modulates Vomeronasal Neuron Response to Male Salamander Pheromone
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Celeste R. Wirsig-Wiechmann
2012-01-01
Full Text Available Electrophysiological studies have shown that gonadotropin-releasing hormone (GnRH modifies chemosensory neurons responses to odors. We have previously demonstrated that male Plethodon shermani pheromone stimulates vomeronasal neurons in the female conspecific. In the present study we used agmatine uptake as a relative measure of the effects of GnRH on this pheromone-induced neural activation of vomeronasal neurons. Whole male pheromone extract containing 3 millimolar agmatine with or without 10 micromolar GnRH was applied to the nasolabial groove of female salamanders for 45 minutes. Immunocytochemical procedures were conducted to visualize and quantify relative agmatine uptake as measured by labeling density of activated vomeronasal neurons. The relative number of labeled neurons did not differ between the two groups: pheromone alone or pheromone-GnRH. However, vomeronasal neurons exposed to pheromone-GnRH collectively demonstrated higher labeling intensity, as a percentage above background (75% as compared with neurons exposed to pheromone alone (63%, P < 0.018. Since the labeling intensity of agmatine within neurons signifies the relative activity levels of the neurons, these results suggest that GnRH increases the response of female vomeronasal neurons to male pheromone.
3. Mating Disruption of the Navel Orangeworm (Lepidoptera: Pyralidae) Using Widely Spaced, Aerosol Dispensers: Is the Pheromone Blend the Most Efficacious Disruptant?
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Higbee, Bradley S; Burks, Charles S; Cardé, Ring T
2017-10-01
The navel orangeworm, Amyelois transitella (Walker) (Lepidoptera: Pyralidae), is a key pest of almonds and pistachios and is sometimes controlled using mating disruption as part of a program of integrated management. The formulation used has a single, nonattractive compound [(11Z,13Z)-hexadecadienal] as the active ingredient that is emitted from timed aerosol dispensers. This study compared this nonattractive, single-compound formulation with two aerosol formulations also containing two additional compounds [(11Z,13Z)-hexadecadien-1-ol and (3Z,6Z,9Z,12Z,15Z)-tricosapentaene] that are found in the pheromone glands, and that in combination with the aldehyde are attractive in wind-tunnel and field-attraction trials. An experiment in pistachios found 97% to 99% suppression of males captured in female-baited traps and 82-93% suppression of mating in sentinel females. Both assays revealed a trend to greater suppression by the more complete pheromone formulations. In almonds, where the abundance of navel orangeworm was lower, all three formulations suppressed males captured in traps and mating in sentinel females by >99%. Each of the formulations significantly reduced damage to Nonpareil almonds. In almonds, there were no significant differences among the formulations in disruption of sexual communication or in damage. These findings suggest that it may be possible to make mating disruption more cost-effective and to achieve higher levels of mating disruption by using attractive aerosol formulations to reduce the number of dispenser per ha. Such a formulation, however, would be more expensive to register in the United States than pheromones meeting the definition of straight-chain lepidopteran pheromone, including the currently used aldehyde-only formulation. Published by Oxford University Press on behalf of Entomological Society of America 2017. This work is written by (a) US Government employee(s) and is in the public domain in the US.
4. Queen pheromones: The chemical crown governing insect social life
DEFF Research Database (Denmark)
Holman, Luke
2010-01-01
Group-living species produce signals that alter the behavior and even the physiology of their social partners. Social insects possess especially sophisticated chemical communication systems that govern every aspect of colony life, including the defining feature of eusociality: reproductive division...... of labor. Current evidence hints at the central importance of queen pheromones, but progress has been hindered by the fact that such pheromones have only been isolated in honeybees. In a pair of papers on the ant Lasius niger, we identified and investigated a queen pheromone regulating worker sterility...... with other studies, these results indicate that queen pheromones are honest signals of quality that simultaneously regulate multiple social behaviors....
5. Insectivorous birds eavesdrop on the pheromones of their prey.
Science.gov (United States)
Saavedra, Irene; Amo, Luisa
2018-01-01
Chemical cues play a fundamental role in mate attraction and mate choice. Lepidopteran females, such as the winter moth (Operophtera brumata), emit pheromones to attract males in the reproductive period. However, these chemical cues could also be eavesdropped by predators. To our knowledge, no studies have examined whether birds can detect pheromones of their prey. O. brumata adults are part of the winter diet of some insectivorous tit species, such as the great tit (Parus major) and blue tit (Cyanistes caeruleus). We performed a field experiment aimed to disentangle whether insectivorous birds can exploit the pheromones emitted by their prey for prey location. We placed artificial larvae and a dispenser on branches of Pyrenean oak trees (Quercus pyrenaica). In half of the trees we placed an O. brumata pheromone dispenser and in the other half we placed a control dispenser. We measured the predation rate of birds on artificial larvae. Our results show that more trees had larvae with signs of avian predation when they contained an O. brumata pheromone than when they contained a control dispenser. Furthermore, the proportion of artificial larvae with signs of avian predation was greater in trees that contained the pheromone than in control trees. Our results indicate that insectivorous birds can exploit the pheromones emitted by moth females to attract males, as a method of prey detection. These results highlight the potential use of insectivorous birds in the biological control of insect pests.
6. Use of Mixture Designs to Investigate Contribution of Minor Sex Pheromone Components to Trap Catch of the Carpenterworm Moth, Chilecomadia valdiviana.
Science.gov (United States)
Lapointe, Stephen L; Barros-Parada, Wilson; Fuentes-Contreras, Eduardo; Herrera, Heidy; Kinsho, Takeshi; Miyake, Yuki; Niedz, Randall P; Bergmann, Jan
2017-12-01
Field experiments were carried out to study responses of male moths of the carpenterworm, Chilecomadia valdiviana (Lepidoptera: Cossidae), a pest of tree and fruit crops in Chile, to five compounds previously identified from the pheromone glands of females. Previously, attraction of males to the major component, (7Z,10Z)-7,10-hexadecadienal, was clearly demonstrated while the role of the minor components was uncertain due to the use of an experimental design that left large portions of the design space unexplored. We used mixture designs to study the potential contributions to trap catch of the four minor pheromone components produced by C. valdiviana. After systematically exploring the design space described by the five pheromone components, we concluded that the major pheromone component alone is responsible for attraction of male moths in this species. The need for appropriate experimental designs to address the problem of assessing responses to mixtures of semiochemicals in chemical ecology is described. We present an analysis of mixture designs and response surface modeling and an explanation of why this approach is superior to commonly used, but statistically inappropriate, designs.
7. Activity of male pheromone of Melanesian rhinoceros beetle Scapanes australis.
Science.gov (United States)
Rochat, Didier; Morin, Jean-Paul; Kakul, Titus; Beaudoin-Ollivier, Laurence; Prior, Robert; Renou, Michel; Malosse, Isabelle; Stathers, Tanya; Embupa, Sebastian; Laup, Samson
2002-03-01
Laboratory and field investigations were carried out to investigate the nature and role of the male pheromone emitted by the Dynast beetle Scapanes australis and to develop a mass trapping technique against this major coconut pest in Papua New Guinea. We report the biological data obtained from natural and synthetic pheromone, previously described as an 84:12:4 (w/w) mixture of 2-butanol (1), 3-hydoxy-2-butanone (2), and 2,3-butanediol (3). EAG recordings from natural and synthetic pheromone and a pitfall olfactometer were poorly informative. In contrast, extensive field trapping trials with various synthetic pheromone mixtures and doses showed that 1 and 2 (formulated in polyethylene sachets in 90:5 v/v ratio) were necessary and sufficient for optimum long-range attraction. Beetles were captured in traps baited with racemic 1 plus 2, with or without a stereoisomer mixture of 3 (2.5- to 2500-mg/day doses). Plant pieces, either sugarcane or coconut, enhanced captures by the synthetic pheromone, which was active alone. Traps with the pheromone caught both sexes in a 3:2 female-male ratio. A pheromone-based mass trapping led to the capture of 2173 beetles in 14 traps surrounding 40 ha of a cocoa-coconut plantation. The captures followed a log-linear decrease during the 125-week trapping program. The role of the male pheromone and its potential for crop protection are discussed.
8. Functional Studies of Sex Pheromone Receptors in Asian Corn Borer Ostrinia furnacalis
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Wei Liu
2018-05-01
Full Text Available Lepidopteran insects use sex pheromones for sexual communication. Pheromone receptors expressed on peripheral olfactory receptor neurons (ORNs are critical part to detect the sex pheromones. In genus Ostrinia, several pheromone receptors were functional analyzed in O. nubilalis and O. scapulalis but the knowledge in O. furnacalis was rare. In this study, seven pheromone receptors were deorphanized by heterologous expression system of Xenopus oocytes. Functional types of sensilla trichoidea were classified by single sensillum recordings to interpret the response pattern of olfactory sensory neurons to Ostrinia pheromone components. OfurOR4 and OfurOR6 responded to the major sex pheromone Z/E12-14:OAc. OfurOR4 is the main receptor for both Z/E12-14:OAc and OfurOR6 mainly responded to E12-14:OAc. Functional differentiation of gene duplication were found between OfurOR5a and OfurOR5b. OfurOR5b showed a broad response to most of the pheromone components in O. furnacalis, whereas OfurOR5a was found without ligands. OfurOR7 showed a specific response to Z9-14:OAc and OfurOR8 mainly responded to Z11-14:OAc and E11-14:OAc. OfurOR3 did not respond to any pheromone components. Our results improved the current knowledge of pheromone reception in Ostrinia species which may contribute to speciation.
9. Existence of a sex pheromone in Triatoma infestans (Hemiptera: Reduvidae: II. Electrophysiological correlates
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Maria G. de Brito Sanchez
1995-10-01
Full Text Available The stimulus provided by a copulating pair of Triatoma infestans significantly affects the electrical activity of the nervous system of Triatoma infestans. Electrophysiological recordings were perfomed on stationary adult males presented with stimuli of an air current carrying odors from males, females, non-copulating pairs and mating pairs. The electrophysiological response was characterized by the low frequency occurrence of biphasic compound impulses. A significant increase in the frequency of the impulses occurred in stationary males when exposed to air currents of mating pairs, when compared to that evoked by a clean air stream. Analysis of the time course of the assays, showed that the electrophisiological activity during the copula was higher than prior to or after copula. The electrophysiological evidence presented here strongly supports the existence of pheromone(s released by one or both sexes during mating and which is perceived by male chemoreceptors located on the antennae.
10. Trail Pheromone Disruption of Argentine Ant Trail Formation and Foraging
Science.gov (United States)
Suckling, D.M.; Peck, R.W.; Stringer, L.D.; Snook, K.; Banko, P.C.
2010-01-01
Trail pheromone disruption of invasive ants is a novel tactic that builds on the development of pheromone-based pest management in other insects. Argentine ant trail pheromone, (Z)-9-hexadecenal, was formulated as a micro-encapsulated sprayable particle and applied against Argentine ant populations in 400 m2 field plots in Hawai'i Volcanoes National Park. A widely dispersed point source strategy for trail pheromone disruption was used. Traffic rates of ants in bioassays of treated filter paper, protected from rainfall and sunlight, indicated the presence of behaviorally significant quantities of pheromone being released from the formulation for up to 59 days. The proportion of plots, under trade wind conditions (2-3 m s-1), with visible trails was reduced for up to 14 days following treatment, and the number of foraging ants at randomly placed tuna-bait cards was similarly reduced. The success of these trail pheromone disruption trials in a natural ecosystem highlights the potential of this method for control of invasive ant species in this and other environments. ?? Springer Science+Business Media, LLC 2010.
11. Hourly and seasonable variation in catch of winter moths and bruce spanworm in pheromone-baited traps
Science.gov (United States)
Joseph Elkinton; Natalie Leva; George Boettner; Roy Hunkins; Marinko. Sremac
2011-01-01
Elkinton et al. recently completed a survey of northeastern North America for the newly invasive winter moth, Operophtera brumata L. The survey used traps baited with the winter moth pheromone, which, as far as it is known, consists of a single compound that is also used by Bruce spanworm, the North American congener of winter moth, O....
12. Sex pheromone and period gene characterization of Lutzomyia longipalpis sensu lato (Lutz & Neiva) (Diptera: Psychodidae) from Posadas, Argentina.
Science.gov (United States)
Salomón, Oscar D; Araki, Alejandra S; Hamilton, James Gc; Acardi, Soraya A; Peixoto, Alexandre A
2010-11-01
Lutzomyia longipalpis s.l. is the primary vector of Leishmania (L.) infantum in the New World. In this study, male Lutzomyia longipalpis specimens from Posadas, Argentina were characterized for two polymorphic markers: the male sex pheromone and the period (per) gene. The male sex pheromone was identified as (S)-9-methylgermacrene-B, the same compound produced by Lu. longipalpis from Paraguay and many populations from Brazil. The analysis of per gene sequences revealed that the population from Argentina is significantly differentiated from previously studied Brazilian populations. Marker studies could contribute to the understanding of the distribution and spread of urban American visceral leishmaniasis, thus aiding in the design of regional surveillance and control strategies.
13. Evidence for volatile male-produced pheromone in banana weevilCosmopolites sordidus.
Science.gov (United States)
Budenberg, W J; Ndiege, I O; Karago, F W
1993-09-01
Females of the banana weevil,Cosmopolites sordidus, were attracted to and made longer visits to live conspecific males, trapped volatiles from males, and dissected male hindguts in a still-air olfactometer. Male weevils were attracted to volatiles trapped from males and made longer visits to live males and volatiles from males. Live females, collected volatiles from females and female hindguts, elicited small or no behavioral responses from either sex. Electroantennogram (EAG) responses from both male and female antennae were elicited by collected volatiles from males and by dichloromethane extracts of male hindguts and bodies but not by surface washes of males. No significant EAG responses were given to equivalent material from females. It is therefore suggested that male banana weevils release an aggregation pheromone via their hindgut.
14. Genetic Control of Conventional and Pheromone-Stimulated Biofilm Formation in Candida albicans
Science.gov (United States)
Lin, Ching-Hsuan; Kabrawala, Shail; Fox, Emily P.; Nobile, Clarissa J.; Johnson, Alexander D.; Bennett, Richard J.
2013-01-01
Candida albicans can stochastically switch between two phenotypes, white and opaque. Opaque cells are the sexually competent form of C. albicans and therefore undergo efficient polarized growth and mating in the presence of pheromone. In contrast, white cells cannot mate, but are induced – under a specialized set of conditions – to form biofilms in response to pheromone. In this work, we compare the genetic regulation of such “pheromone-stimulated” biofilms with that of “conventional” C. albicans biofilms. In particular, we examined a network of six transcriptional regulators (Bcr1, Brg1, Efg1, Tec1, Ndt80, and Rob1) that mediate conventional biofilm formation for their potential roles in pheromone-stimulated biofilm formation. We show that four of the six transcription factors (Bcr1, Brg1, Rob1, and Tec1) promote formation of both conventional and pheromone-stimulated biofilms, indicating they play general roles in cell cohesion and biofilm development. In addition, we identify the master transcriptional regulator of pheromone-stimulated biofilms as C. albicans Cph1, ortholog of Saccharomyces cerevisiae Ste12. Cph1 regulates mating in C. albicans opaque cells, and here we show that Cph1 is also essential for pheromone-stimulated biofilm formation in white cells. In contrast, Cph1 is dispensable for the formation of conventional biofilms. The regulation of pheromone- stimulated biofilm formation was further investigated by transcriptional profiling and genetic analyses. These studies identified 196 genes that are induced by pheromone signaling during biofilm formation. One of these genes, HGC1, is shown to be required for both conventional and pheromone-stimulated biofilm formation. Taken together, these observations compare and contrast the regulation of conventional and pheromone-stimulated biofilm formation in C. albicans, and demonstrate that Cph1 is required for the latter, but not the former. PMID:23637598
15. The water-borne protein signals (pheromones) of the Antarctic ciliated protozoan Euplotes nobilii: structure of the gene coding for the En-6 pheromone.
Science.gov (United States)
La Terza, Antonietta; Dobri, Nicoleta; Alimenti, Claudio; Vallesi, Adriana; Luporini, Pierangelo
2009-01-01
The marine Antarctic ciliate, Euplotes nobilii, secretes a family of water-borne signal proteins, denoted as pheromones, which control vegetative proliferation and mating in the cell. Based on the knowledge of the amino acid sequences of a set of these pheromones isolated from the culture supernatant of wild-type strains, we designed probes to identify their encoding genes in the cell somatic nucleus (macronucleus). The full-length gene of the pheromone En-6 was determined and found to contain an open-reading frame specific for the synthesis of the En-6 cytoplasmic precursor (pre-pro-En-6), which requires 2 proteolytic cleavages to remove the signal peptide (pre) and the prosegment before secretion of the mature protein. In contrast to the sequence variability that distinguishes the secreted pheromones, the pre- and pro-sequences appear to be tightly conserved and useful for the construction of probes to clone every other E. nobilii pheromone gene. Potential intron sequences in the coding region of the En-6 gene imply the synthesis of more En-6 isoforms.
16. Sexy DEG/ENaC channels involved in gustatory detection of fruit fly pheromones.
Science.gov (United States)
Pikielny, Claudio W
2012-11-06
Hydrocarbon pheromones on the cuticle of Drosophila melanogaster modulate the complex courtship behavior of males. Recently, three members of the degenerin/epithelial Na+ channel (DEG/ENaC) family of sodium channel subunits, Ppk25, Ppk23, and Ppk29 (also known as Nope), have been shown to function in gustatory perception of courtship-modulating contact pheromones. All three proteins are required for the activation of male courtship by female pheromones. Specific interactions between two of them have been demonstrated in cultured cells, suggesting that, in a subset of cells where they are coexpressed, these three subunits function within a common heterotrimeric DEG/ENaC channel. Such a DEG/ENaC channel may be gated by pheromones, either directly or indirectly, or alternatively may control the excitability of pheromone-sensing cells. In addition, these studies identify taste neurons that respond specifically to courtship-modulating pheromones and mediate their effects on male behavior. Two types of pheromone-sensing taste neurons, F and M cells, have been defined on the basis of their specific response to either female or male pheromones. These reports set the stage for the dissection of the molecular and cellular mechanisms that mediate gustatory detection of contact pheromones.
17. An End-to-End Model of Plant Pheromone Channel for Long Range Molecular Communication.
Science.gov (United States)
Unluturk, Bige D; Akyildiz, Ian F
2017-01-01
A new track in molecular communication is using pheromones which can scale up the range of diffusion-based communication from μm meters to meters and enable new applications requiring long range. Pheromone communication is the emission of molecules in the air which trigger behavioral or physiological responses in receiving organisms. The objective of this paper is to introduce a new end-to-end model which incorporates pheromone behavior with communication theory for plants. The proposed model includes both the transmission and reception processes as well as the propagation channel. The transmission process is the emission of pheromones from the leaves of plants. The dispersion of pheromones by the flow of wind constitutes the propagation process. The reception process is the sensing of pheromones by the pheromone receptors of plants. The major difference of pheromone communication from other molecular communication techniques is the dispersion channel acting under the laws of turbulent diffusion. In this paper, the pheromone channel is modeled as a Gaussian puff, i.e., a cloud of pheromone released instantaneously from the source whose dispersion follows a Gaussian distribution. Numerical results on the performance of the overall end-to-end pheromone channel in terms of normalized gain and delay are provided.
18. The role of pheromone receptors for communication and mating in Hypocrea jecorina (Trichoderma reesei)
Science.gov (United States)
Seibel, Christian; Tisch, Doris; Kubicek, Christian P.; Schmoll, Monika
2012-01-01
Discovery of sexual development in the ascomycete Trichoderma reesei (Hypocrea jecorina) as well as detection of a novel class of peptide pheromone precursors in this fungus indicates promising insights into its physiology and lifestyle. Here we investigated the role of the two pheromone receptors HPR1 and HPR2 in the H. jecorina pheromone-system. We found that these pheromone receptors show an unexpectedly high genetic variability among H. jecorina strains. HPR1 and HPR2 confer female fertility in their cognate mating types (MAT1-1 or MAT1-2, respectively) and mediate induction of fruiting body development. One compatible pheromone precursor–pheromone receptor pair (hpr1–hpp1 or hpr2–ppg1) in mating partners was sufficient for sexual development. Additionally, pheromone receptors were essential for ascospore development, hence indicating their involvement in post-fertilisation events. Neither pheromone precursor genes nor pheromone receptor genes of H. jecorina were transcribed in a strictly mating type dependent manner, but showed enhanced expression levels in the cognate mating type. In the presence of a mating partner under conditions favoring sexual development, transcript levels of pheromone precursors were significantly increased, while those of pheromone receptor genes do not show this trend. In the female sterile T. reesei strain QM6a, transcriptional responses of pheromone precursor and pheromone receptor genes to a mating partner were clearly altered compared to the female fertile wild-type strain CBS999.97. Consequently, a delayed and inappropriate response to the mating partner may be one aspect causing female sterility in QM6a. PMID:22884620
19. Multiple length peptide-pheromone variants produced by Streptococcus pyogenes directly bind Rgg proteins to confer transcriptional regulation.
Science.gov (United States)
Aggarwal, Chaitanya; Jimenez, Juan Cristobal; Nanavati, Dhaval; Federle, Michael J
2014-08-08
Streptococcus pyogenes, a human-restricted pathogen, accounts for substantial mortality related to infections worldwide. Recent studies indicate that streptococci produce and respond to several secreted peptide signaling molecules (pheromones), including those known as short hydrophobic peptides (SHPs), to regulate gene expression by a quorum-sensing mechanism. Upon transport into the bacterial cell, pheromones bind to and modulate activity of receptor proteins belonging to the Rgg family of transcription factors. Previously, we reported biofilm regulation by the Rgg2/3 quorum-sensing circuit in S. pyogenes. The aim of this study was to identify the composition of mature pheromones from cell-free culture supernatants that facilitate biofilm formation. Bioluminescent reporters were employed to detect active pheromones in culture supernatants fractionated by reverse-phase chromatography, and mass spectrometry was used to characterize their properties. Surprisingly, multiple SHPs that varied by length were detected. Synthetic peptides of each variant were tested individually using bioluminescence reporters and biofilm growth assays, and although activities differed widely among the group, peptides comprising the C-terminal eight amino acids of the full-length native peptide were most active. Direct Rgg/SHP interactions were determined using a fluorescence polarization assay that utilized FITC-labeled peptide ligands. Peptide receptor affinities were seen to be as low as 500 nm and their binding affinities directly correlated with observed bioactivity. Revelation of naturally produced pheromones along with determination of their affinity for cognate receptors are important steps forward in designing compounds whose purpose is positioned for future therapeutics aimed at treating infections through the interference of bacterial communication. © 2014 by The American Society for Biochemistry and Molecular Biology, Inc.
20. Identification and field evaluation of attractants for the cranberry weevil, Anthonomus musculus Say.
Science.gov (United States)
Szendrei, Zsofia; Averill, Anne; Alborn, Hans; Rodriguez-Saona, Cesar
2011-04-01
Studies were conducted to develop an attractant for the cranberry weevil, Anthonomus musculus, a pest of blueberry and cranberry flower buds and flowers in the northeastern United States. In previous studies, we showed that cinnamyl alcohol, the most abundant blueberry floral volatile, and the green leaf volatiles (Z)-3-hexenyl acetate and hexyl acetate, emitted from both flowers and flower buds, elicit strong antennal responses from A. musculus. Here, we found that cinnamyl alcohol did not increase capture of A. musculus adults on yellow sticky traps compared with unbaited controls; however, weevils were highly attracted to traps baited with the Anthonomus eugenii Cano aggregation pheromone, indicating that these congeners share common pheromone components. To identify the A. musculus aggregation pheromone, headspace volatiles were collected from adults feeding on blueberry or cranberry flower buds and analyzed by gas chromatography-mass spectrometry. Three male-specific compounds were identified: (Z)-2-(3,3-dimethyl-cyclohexylidene) ethanol (Z grandlure II); (Z)-(3,3-dimethylcyclohexylidene) acetaldehyde (grandlure III); and (E)-(3,3- dimethylcyclohexylidene) acetaldehyde (grandlure IV). A fourth component, (E)-3,7-dimethyl-2,6-octadien-1-ol (geraniol), was emitted in similar quantities by males and females. The emission rates of these volatiles were about 2.8, 1.8, 1.3, and 0.9 ng/adult/d, respectively. Field experiments in highbush blueberry (New Jersey) and cranberry (Massachusetts) examined the attraction of A. musculus to traps baited with the male-produced compounds and geraniol presented alone and combined with (Z)-3-hexenyl acetate and hexyl acetate, and to traps baited with the pheromones of A. eugenii and A. grandis. In both states and crops, traps baited with the A. musculus male-produced compounds attracted the highest number of adults. Addition of the green leaf volatiles did not affect A. musculus attraction to its pheromone but skewed the sex ratio
1. Peripheral, central and behavioral responses to the cuticular pheromone bouquet in Drosophila melanogaster males.
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Tsuyoshi Inoshita
Full Text Available Pheromonal communication is crucial with regard to mate choice in many animals including insects. Drosophila melanogaster flies produce a pheromonal bouquet with many cuticular hydrocarbons some of which diverge between the sexes and differently affect male courtship behavior. Cuticular pheromones have a relatively high weight and are thought to be -- mostly but not only -- detected by gustatory contact. However, the response of the peripheral and central gustatory systems to these substances remains poorly explored. We measured the effect induced by pheromonal cuticular mixtures on (i the electrophysiological response of peripheral gustatory receptor neurons, (ii the calcium variation in brain centers receiving these gustatory inputs and (iii the behavioral reaction induced in control males and in mutant desat1 males, which show abnormal pheromone production and perception. While male and female pheromones induced inhibitory-like effects on taste receptor neurons, the contact of male pheromones on male fore-tarsi elicits a long-lasting response of higher intensity in the dedicated gustatory brain center. We found that the behavior of control males was more strongly inhibited by male pheromones than by female pheromones, but this difference disappeared in anosmic males. Mutant desat1 males showed an increased sensitivity of their peripheral gustatory neurons to contact pheromones and a behavioral incapacity to discriminate sex pheromones. Together our data indicate that cuticular hydrocarbons induce long-lasting inhibitory effects on the relevant taste pathway which may interact with the olfactory pathway to modulate pheromonal perception.
2. Identification of receptors of main sex-pheromone components of three Lepidopteran species.
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Mitsuno, Hidefumi; Sakurai, Takeshi; Murai, Masatoshi; Yasuda, Tetsuya; Kugimiya, Soichi; Ozawa, Rika; Toyohara, Haruhiko; Takabayashi, Junji; Miyoshi, Hideto; Nishioka, Takaaki
2008-09-01
Male moths discriminate conspecific female-emitted sex pheromones. Although the chemical components of sex pheromones have been identified in more than 500 moth species, only three components in Bombyx mori and Heliothis virescens have had their receptors identified. Here we report the identification of receptors for the main sex-pheromone components in three moth species, Plutella xylostella, Mythimna separata and Diaphania indica. We cloned putative sex-pheromone receptor genes PxOR1, MsOR1 and DiOR1 from P. xylostella, M. separata and D. indica, respectively. Each of the three genes was exclusively expressed with an Or83b orthologous gene in male olfactory receptor neurons (ORNs) that are surrounded by supporting cells expressing pheromone-binding-protein (PBP) genes. By two-electrode voltage-clamp recording, we tested the ligand specificity of Xenopus oocytes co-expressing PxOR1, MsOR1 or DiOR1 with an OR83b family protein. Among the seven sex-pheromone components of the three moth species, the oocytes dose-dependently responded only to the main sex-pheromone component of the corresponding moth species. In our study, PBPs were not essential for ligand specificity of the receptors. On the phylogenetic tree of insect olfactory receptors, the six sex-pheromone receptors identified in the present and previous studies are grouped in the same subfamily but have no relation with the taxonomy of moths. It is most likely that sex-pheromone receptors have randomly evolved from ancestral sex-pheromone receptors before the speciation of moths and that their ligand specificity was modified by mutations of local amino acid sequences after speciation.
3. Binding interaction between a queen pheromone component HOB and pheromone binding protein ASP1 of Apis cerana.
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Weng, Chen; Fu, Yuxia; Jiang, Hongtao; Zhuang, Shulin; Li, Hongliang
2015-01-01
The honeybee's social behavior is closely related to the critical response to pheromone, while pheromone binding proteins (PBPs) play an important role in binding and transferring those pheromones. Here we report one known PBP, antennal special protein 1(ASP1), which has high affinity with a queen mandibular pheromone component, methyl-p-hydroxybenzoate (HOB). In this study, multiple fluorescent spectra, UV absorption spectra, circular dichroism (CD) spectra and molecular docking analysis were combined to clarify the binding process. Basically, fluorescence intensity of ASP1 could be considerably quenched by HOB with an appropriate interaction distance (3.1 nm), indicating that a complex, which is more stable in lower temperature, was formed. The fact ΔH < 0, ΔS < 0, by thermodynamic analysis, indicated the van der Waals and hydrogen bond as main driving force. Moreover, synchronous fluorescence spectra and CD spectra analysis showed the change of partial hydrophilicity of ASP1 and the increase of α-helix after HOB addition. In conclusion, ASP1 can strongly and spontaneously interact with HOB. But the binding ability decreases with the rise of temperature, which may be necessary for sufficient social stability of hives. This study provides elucidation of the detailed binding mechanism and potential physicochemical basis of thermal stability to the social behavior of honeybee. Copyright © 2014 Elsevier B.V. All rights reserved.
4. Pheromone and Animal Reproducton: Speciation in Response to ...
African Journals Online (AJOL)
While humans are highly dependent upon visual cues when in close proximity, smell also play a big role in sociosexual behaviours. There is an inherent difficulty in studying human pheromones because of the need for cleanliness and odourlessness in human participants. Pheromones are often divided by function into two: ...
5. Effect of Brood Pheromone on Survival and Nutrient Intake of African Honey Bees (Apis mellifera scutellata) under Controlled Conditions.
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Démares, Fabien J; Yusuf, Abdullahi A; Nicolson, Susan W; Pirk, Christian W W
2017-05-01
The influence of pheromones on insect physiology and behavior has been thoroughly reported for numerous aspects, such as attraction, gland development, aggregation, mate and kin recognition. Brood pheromone (BP) is released by honey bee larvae to indicate their protein requirements to the colony. Although BP is known to modulate pollen and protein consumption, which in turn can affect physiological and morphological parameters, such as hypopharyngeal gland (HPG) development and ovarian activation, few studies have focused on the effect of BP on nutritional balance. In this study, we exposed newly emerged worker bees for 14 d and found that BP exposure increased protein intake during the first few days, with a peak in consumption at day four following exposure. BP exposure decreased survival of caged honey bees, but did not affect either the size of the HPG acini or ovarian activation stage. The uncoupling of the BP releaser effect, facilitated by working under controlled conditions, and the presence of larvae as stimulating cues are discussed.
6. Semi-selective fatty acyl reductases from four heliothine moths influence the specific pheromone composition
NARCIS (Netherlands)
Hagström, Å.K; Liénard, M.A.; Groot, A.T.; Hedenström, E; Löfstedt, C.
2012-01-01
Background: Sex pheromones are essential in moth mate communication. Information on pheromone biosynthetic genes and enzymes is needed to comprehend the mechanisms that contribute to specificity of pheromone signals. Most heliothine moths use sex pheromones with (Z)-11-hexadecenal as the major
7. Saproxylic community, guild and species responses to varying pheromone components of a pine bark beetle.
Science.gov (United States)
Etxebeste, Iñaki; Lencina, José L; Pajares, Juan
2013-10-01
Some bark beetle species (Coleoptera: Scolytinae) produce aggregation pheromones that allow coordinated attack on their conifer hosts. As a new saproxylic habitat is founded, an assemblage of associated beetles kairomonally respond to bark beetle infochemicals. Ips sexdentatus is one of the major damaging insects of Pinus spp. in Southern Europe. Its response to varying ipsenol (Ie) percentages in relation to ipsdienol (Id) was studied in northwestern Spain, along with the entire saproxylic beetle assemblage captured at multiple-funnel traps. Response profile modeling was undertaken for I. sexdentatus sexes and sex-ratios, associated species and for selected trophic groups using a reference Gaussian model. In addition, the effects on the saproxylic assemblages were analyzed. I. sexdentatus response curve peaked at 22.7% Ie content, while remaining taxa that could be modeled, peaked above ca. 40% Ie. Predator guilds showed a linear relationship with Ie proportion, while competitors showed a delayed response peak. Consequently, species assemblages differed markedly between varying pheromone component mixtures. Given that the evaluated pheromonal proportions mimicked that of logs being colonized by I. sexdentatus, results suggested that the registered differential responses at different levels might provide I. sexdentatus with a temporal window that maximizes conspecific attraction while reducing interference with competitor and predatory guilds. Described responses might help improve the monitoring of the population status of target bark beetles and their associates, but also point toward the by-catch of many natural enemies, as well as rare saproxylic beetle species, interfering with the aims of sustainable forest management.
8. Temperature limits trail following behaviour through pheromone decay in ants
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van Oudenhove, Louise; Billoir, Elise; Boulay, Raphaël; Bernstein, Carlos; Cerdá, Xim
2011-12-01
In Mediterranean habitats, temperature affects both ant foraging behaviour and community structure. Many studies have shown that dominant species often forage at lower temperature than subordinates. Yet, the factors that constrain dominant species foraging activity in hot environments are still elusive. We used the dominant ant Tapinoma nigerrimum as a model species to test the hypothesis that high temperatures hinder trail following behaviour by accelerating pheromone degradation. First, field observations showed that high temperatures (> 30°C) reduce the foraging activity of T. nigerrimum independently of the daily and seasonal rhythms of this species. Second, we isolated the effect of high temperatures on pheromone trail efficacy from its effect on worker physiology. A marked substrate was heated during 10 min (five temperature treatments from 25°C to 60°C), cooled down to 25°C, and offered in a test choice to workers. At hot temperature treatments (>40°C), workers did not discriminate the previously marked substrate. High temperatures appeared therefore to accelerate pheromone degradation. Third, we assessed the pheromone decay dynamics by a mechanistic model fitted with Bayesian inference. The model predicted ant choice through the evolution of pheromone concentration on trails as a function of both temperature and time since pheromone deposition. Overall, our results highlighted that the effect of high temperatures on recruitment intensity was partly due to pheromone evaporation. In the Mediterranean ant communities, this might affect dominant species relying on chemical recruitment, more than subordinate ant species, less dependent on chemical communication and less sensitive to high temperatures.
9. Two pheromone precursor genes are transcriptionally expressed in the homothallic ascomycete Sordaria macrospora.
Science.gov (United States)
Pöggeler, S
2000-06-01
In order to analyze the involvement of pheromones in cell recognition and mating in a homothallic fungus, two putative pheromone precursor genes, named ppg1 and ppg2, were isolated from a genomic library of Sordaria macrospora. The ppg1 gene is predicted to encode a precursor pheromone that is processed by a Kex2-like protease to yield a pheromone that is structurally similar to the alpha-factor of the yeast Saccharomyces cerevisiae. The ppg2 gene encodes a 24-amino-acid polypeptide that contains a putative farnesylated and carboxy methylated C-terminal cysteine residue. The sequences of the predicted pheromones display strong structural similarity to those encoded by putative pheromones of heterothallic filamentous ascomycetes. Both genes are expressed during the life cycle of S. macrospora. This is the first description of pheromone precursor genes encoded by a homothallic fungus. Southern-hybridization experiments indicated that ppg1 and ppg2 homologues are also present in other homothallic ascomycetes.
10. Resisting majesty: Apis cerana, has lower antennal sensitivity and decreased attraction to queen mandibular pheromone than Apis mellifera
OpenAIRE
Shihao Dong; Ping Wen; Qi Zhang; Xinyu Li; Ken Tan; James Nieh
2017-01-01
In highly social bees, queen mandibular pheromone (QMP) is vital for colony life. Both Apis cerana (Ac) and Apis mellifera (Am) share an evolutionarily conserved set of QMP compounds: (E)-9-oxodec-2-enoic acid (9-ODA), (E)-9-hydroxydec-2-enoic acid (9-HDA), (E)-10-hydroxy-dec-2-enoic acid (10-HDA), 10-hydroxy-decanoic acid (10-HDAA), and methyl p?hydroxybenzoate (HOB) found at similar levels. However, evidence suggests there may be species-specific sensitivity differences to QMP compounds bec...
11. Sensory reception of the primer pheromone ethyl oleate
Science.gov (United States)
Muenz, Thomas S.; Maisonnasse, Alban; Plettner, Erika; Le Conte, Yves; Rössler, Wolfgang
2012-05-01
Social work force distribution in honeybee colonies critically depends on subtle adjustments of an age-related polyethism. Pheromones play a crucial role in adjusting physiological and behavioral maturation of nurse bees to foragers. In addition to primer effects of brood pheromone and queen mandibular pheromone—both were shown to influence onset of foraging—direct worker-worker interactions influence adult behavioral maturation. These interactions were narrowed down to the primer pheromone ethyl oleate, which is present at high concentrations in foragers, almost absent in young bees and was shown to delay the onset of foraging. Based on chemical analyses, physiological recordings from the antenna (electroantennograms) and the antennal lobe (calcium imaging), and behavioral assays (associative conditioning of the proboscis extension response), we present evidence that ethyl oleate is most abundant on the cuticle, received by olfactory receptors on the antenna, processed in glomeruli of the antennal lobe, and learned in olfactory centers of the brain. The results are highly suggestive that the primer pheromone ethyl oleate is transmitted and perceived between individuals via olfaction at close range.
12. Pheromones: a new ergogenic aid in sport?
Science.gov (United States)
Papaloucas, Marios; Kyriazi, Kyriaki; Kouloulias, Vassilis
2015-10-01
Nowadays, antidoping laboratories are improving detection methods to confirm the use of forbidden substances. These tests are based both on direct identification of new substances or their metabolites and on indirect evaluation of changes in gene, protein, or metabolite patterns (genomics, proteomics, or metabolomics). The World Anti-Doping Agency (WADA) officially monitors anabolic steroids, hormones, growth factors, β-agonists, hormone and metabolic modulators, masking agents, street drugs, manipulation of blood and blood components, chemical and physical manipulation, gene doping, stimulants, narcotics, glucocorticosteroids, and β-blockers. However, several other substances are under review by WADA. Pheromones accomplish the structure and function of life from its first step, while they have an impact on the body's performance. Both testosterone and pheromones have an ergogenic effect that could potentially affect an athlete's performance. The authors share their questions concerning the potential impact of pheromones in sports.
13. Male Sexual Behavior and Pheromone Emission Is Enhanced by Exposure to Guava Fruit Volatiles in Anastrepha fraterculus.
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Guillermo E Bachmann
Full Text Available Plant chemicals can affect reproductive strategies of tephritid fruit flies by influencing sex pheromone communication and increasing male mating competitiveness.We explored whether exposure of Anastrepha fraterculus males to guava fruit volatiles and to a synthetic blend of volatile compounds released by this fruit affects the sexual performance of wild and laboratory flies. By means of bioassays and pheromone collection we investigated the mechanism underlying this phenomenon.Guava volatile exposure enhanced male mating success and positively affected male calling behavior and pheromone release in laboratory and wild males. Changes in male behavior appear to be particularly important during the initial phase of the sexual activity period, when most of the mating pairs are formed. Exposure of laboratory males to a subset of guava fruit volatiles enhanced mating success, showing that the response to the fruit might be mimicked artificially.Volatiles of guava seem to influence male mating success through an enhancement of chemical and physical signals related to the communication between sexes. This finding has important implications for the management of this pest species through the Sterile Insect Technique. We discuss the possibility of using artificial blends to improve the sexual competitiveness of sterile males.
14. How flies respond to honey bee pheromone: the role of the foraging gene on reproductive response to queen mandibular pheromone
Science.gov (United States)
Camiletti, Alison L.; Awde, David N.; Thompson, Graham J.
2014-01-01
In this study we test one central prediction from sociogenomic theory—that social and non-social taxa share common genetic toolkits that regulate reproduction in response to environmental cues. We exposed Drosophila females of rover ( for R) and sitter ( for s) genotypes to an ovary-suppressing pheromone derived from the honeybee Apis mellifera. Surprisingly, queen mandibular pheromone (QMP) affected several measures of fitness in flies, and in a manner comparable to the pheromone's normal effect on bee workers. QMP-treated sitter flies had smaller ovaries that contained fewer eggs than did untreated controls. QMP-treated rover flies, by contrast, showed a more variable pattern that only sometimes resulted in ovary inhibition, while a third strain of fly that contains a sitter mutant allele in a rover background ( for s2) showed no ovarian response to QMP. Taken together, our results suggest that distinctly non-social insects have some capacity to respond to social cues, but that this response varies with fly genotype. In general, the interspecific response is consistent with a conserved gene set affecting reproductive physiology. The differential response among strains in particular suggests that for is itself important for modulating the fly's pheromonal response.
15. Synthesis of tritiated sex pheromones of the processionary moth Thaumetopoea pityocampa and the Egyptian armyworm Spodoptera littoralis
International Nuclear Information System (INIS)
Guerrero, Angel; Feixas, Joan
1996-01-01
Synthesis of tritiated sex phenomones of the processionary moth Thaumetopoea pityocampa and the Egyptian armyworm Spodoptera littoralis has been accomplished by a simple route involving tritiated sodium borohydride reduction of the corresponding aldehyde followed by acetylation of the resulting radiolabelled alcohol. The process occurs with high chemical and radiochemical yields and the compounds have been used in pheromone catabolism studies. (author)
16. Shifts in sensory neuron identity parallel differences in pheromone preference in the European corn borer
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Fotini A Koutroumpa
2014-10-01
Full Text Available Pheromone communication relies on highly specific signals sent and received between members of the same species. However, how pheromone specificity is determined in moth olfactory circuits remains unknown. Here we provide the first glimpse into the mechanism that generates this specificity in Ostrinia nubilalis. In Ostrinia nubilalis it was found that a single locus causes strain-specific, diametrically opposed preferences for a 2-component pheromone blend. Previously we found pheromone preference to be correlated with the strain and hybrid-specific relative antennal response to both pheromone components. This led to the current study, in which we detail the underlying mechanism of this differential response, through chemotopically mapping of the pheromone detection circuit in the antenna. We determined that both strains and their hybrids have swapped the neuronal identity of the pheromone-sensitive neurons co-housed within a single sensillum. Furthermore, neurons that mediate behavioral antagonism surprisingly co-express up to five pheromone receptors, mirroring the concordantly broad tuning to heterospecific pheromones. This appears as possible evolutionary adaptation that could prevent cross attraction to a range of heterospecific signals, while keeping the pheromone detection system to its simplest tripartite setup.
17. Alarm pheromone does not modulate 22-kHz calls in male rats.
Science.gov (United States)
Muyama, Hiromi; Kiyokawa, Yasushi; Inagaki, Hideaki; Takeuchi, Yukari; Mori, Yuji
2016-03-15
Rats are known to emit a series of ultrasonic vocalizations, termed 22-kHz calls, when exposed to distressing stimuli. Pharmacological studies have indicated that anxiety mediates 22-kHz calls in distressed rats. We previously found that exposure to the rat alarm pheromone increases anxiety in rats. Therefore, we hypothesized that the alarm pheromone would increase 22-kHz calls in pheromone-exposed rats. Accordingly, we tested whether exposure to the alarm pheromone induced 22-kHz calls, as well as whether the alarm pheromone increased 22-kHz calls in response to an aversive conditioned stimulus (CS). Rats were first fear-conditioned to an auditory and contextual CS. On the following day, the rats were either exposed to the alarm pheromone or a control odor that was released from the neck region of odor-donor rats. Then, the rats were re-exposed to the aversive CS. The alarm pheromone neither induced 22-kHz calls nor increased 22-kHz calls in response to the aversive CS. In contrast, the control odor unexpectedly reduced the total number and duration of 22-kHz calls elicited by the aversive CS, as well as the duration of freezing. These results suggest that the alarm pheromone does not affect 22-kHz calls in rats. However, we may have found evidence for an appeasing olfactory signal, released from the neck region of odor-donor rats. Copyright © 2016 Elsevier Inc. All rights reserved.
18. Pheromone-modulated behavioral suites influence colony growth in the honey bee (Apis mellifera)
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Pankiw, Tanya; Roman, Roman; Sagili, Ramesh R.; Zhu-Salzman, Keyan
2004-12-01
The success of a species depends on its ability to assess its environment and to decide accordingly which behaviors are most appropriate. Many animal species, from bacteria to mammals, are able to communicate using interspecies chemicals called pheromones. In addition to exerting physiological effects on individuals, for social species, pheromones communicate group social structure. Communication of social structure is important to social insects for the allocation of its working members into coordinated suites of behaviors. We tested effects of long-term treatment with brood pheromone on suites of honey bee brood rearing and foraging behaviors. Pheromone-treated colonies reared significantly greater brood areas and more adults than controls, while amounts of stored pollen and honey remained statistically similar. Brood pheromone increased the number of pollen foragers and the pollen load weights they returned. It appeared that the pheromone-induced increase in pollen intake was directly canalized into more brood rearing. A two-way pheromone priming effect was observed, such that some workers from the same age cohorts showed an increased and extended capacity to rear larvae, while others were recruited at significantly younger ages into pollen-specific foraging. Brood pheromone affected suites of nursing and foraging behaviors allocating worker and pollen resources associated with an important fitness trait, colony growth.
19. System of forest insect pheromone communication: stability of «information» molecules to environmental factors
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V. G. Soukhovolsky
2016-06-01
Full Text Available Features of external environmental factors (such as electromagnetic radiation in certain spectral bands influencing pheromone molecules, which are carriers of information for forest insects in the search of the opposite sex, were examined. Stability of pheromone molecules for external influences has been studied for siberian moth Dendrolimus superans sibiricus Tschetv., pine moth Dendrilimus pini L., gypsy moth Lymantria dispar L., for xylophages Ips typographus L., Monochamus urussovi Fish. and Monochamus galloprovincialis Oliv. Properties of pheromone molecules were evaluated by calculations using quantum-chemical method B3LYP. Existing methods of quantum-chemical calculations are useful for analyzing the properties of quite small and uncomplicated molecules of forest insect pheromones. The calculations showed that the molecules of insect pheromones are able to absorb light in the ultraviolet range and move into an excited state. The values of dipole moments, the wavelengths of the absorption, atomic and molecular electronic properties of pheromones in the ground and excited states were calculated. The calculations showed that for the reaction of pheromones with oxygen an energy barrier is somewhat higher than for reactions of pheromones with water vapor. The worst reaction of pheromones with water molecules likely to pheromones such molecules whose dipole moment is comparable to the dipole moment of water. Quantum-chemical characteristics of the pheromone molecules can be linked to specific behavior of the insects.
20. PHEROMONAL MODULATION OF REPRODUCTIVE FUNCTION IN MAMMALS
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Matthieu Keller
2011-11-01
Full Text Available Social olfactory signals, often known as pheromones, are powerful regulators of reproductive function. These chemosignals can be detected by two olfactory systems, namely the main or the accessory olfactory systems. While initially anatomically segregated, both systems converge functionally as they can detect and process overlapping sets of chemosignals. This convergence also takes place at the level of their central projections in the hypothalamus. It is probably at this level that future investigations will be needed. Indeed, if the physiology of both olfactory system and reproductive function are now quite well characterized, the interrelation between both systems is unclear. Among the many cell populations that can serve as targets or relays for the pheromonal information in the hypothalamus are GnRH cells or the recently discovered Kispeptin population which have been showed to be activated after pheromonal activation. However, many works will be needed before having a definitive picture.
1. NMR structure of navel orangeworm moth pheromone-binding protein (AtraPBP1): implications for pH-sensitive pheromone detection.
Science.gov (United States)
Xu, Xianzhong; Xu, Wei; Rayo, Josep; Ishida, Yuko; Leal, Walter S; Ames, James B
2010-02-23
The navel orangeworm, Amyelois transitella (Walker), is an agricultural insect pest that can be controlled by disrupting male-female communication with sex pheromones, a technique known as mating disruption. Insect pheromone-binding proteins (PBPs) provide fast transport of hydrophobic pheromones through the aqueous sensillar lymph and promote sensitive delivery of pheromones to receptors. Here we present the three-dimensional structure of a PBP from A. transitella (AtraPBP1) in solution at pH 4.5 determined by nuclear magnetic resonance (NMR) spectroscopy. Pulsed-field gradient NMR diffusion experiments, multiangle light scattering, and (15)N NMR relaxation analysis indicate that AtraPBP1 forms a stable monomer in solution at pH 4.5 in contrast to forming mostly dimers at pH 7. The NMR structure of AtraPBP1 at pH 4.5 contains seven alpha-helices (alpha1, L8-L23; alpha2, D27-F36; alpha3, R46-V62; alpha4, A73-M78; alpha5, D84-S100; alpha6, R107-L125; alpha7, M131-E141) that adopt an overall main-chain fold similar to that of PBPs found in Antheraea polyphemus and Bombyx mori. The AtraPBP1 structure is stabilized by three disulfide bonds formed by C19/C54, C50/C108, and C97/C117 and salt bridges formed by H69/E60, H70/E57, H80/E132, H95/E141, and H123/D40. All five His residues are cationic at pH 4.5, whereas H80 and H95 become neutral at pH 7.0. The C-terminal helix (alpha7) contains hydrophobic residues (M131, V133, V134, V135, V138, L139, and A140) that contact conserved residues (W37, L59, A73, F76, A77, I94, V111, and V115) suggested to interact with bound pheromone. Our NMR studies reveal that acid-induced formation of the C-terminal helix at pH 4.5 is triggered by a histidine protonation switch that promotes rapid release of bound pheromone under acidic conditions.
2. Self-aggregation of liquids from biomass in aqueous solution
International Nuclear Information System (INIS)
Lomba, Laura; Giner, Beatriz; Zuriaga, Estefanía; Moya, Juana; Lafuente, Carlos
2013-01-01
Highlights: • Aggregation behaviour of liquids from biomass in aqueous solution has been studied. • Standard Gibbs free energies of aggregation have been calculated. • Solubility in water of these compounds has been determined. • Critical aggregation concentration decreases as the solubility in water does. -- Abstract: Aggregation of several chemicals from biomass: furfural derived compounds (furfural, 5-methylfurfural, furfuryl alcohol and tetrahydrofurfuryl alcohol), lactate derived compounds (methyl lactate, ethyl lactate and butyl lactate), acrylate derived compound (methyl acrylate) and levulinate compounds (methyl levulinate, ethyl levulinate and butyl levulinate) in aqueous solution has been characterised at T = 298.15 K through density, ρ, speed of sound, u, and isentropic compressibilities, κ S , measurements. In addition the standard Gibbs free energies of aggregation have been also calculated. Furthermore, in order to deepen insight the behaviour of these chemicals in aqueous solution, the solubility of these compounds has been measured at T = 298.15 K
3. Short-chain alkanes synergise responses of moth pests to their sex pheromones.
Science.gov (United States)
Gurba, Alexandre; Guerin, Patrick M
2016-05-01
The use of sex pheromones for mating disruption of moth pests of crops is increasing worldwide. Efforts are under way to augment the efficiency and reliability of this control method by adding molecules derived from host plants to the sex attractants in dispensers. We show how attraction of the European grapevine moth, Lobesia botrana Den. & Schiff., and the codling moth, Cydia pomonella L., males to underdosed levels of their sex pheromones is increased by adding heptane or octane over a range of release rates. Pheromone-alkane mixtures enhance male recruitment by up to 30%, reaching levels induced by calling females, and shorten the flight time to the sex attractant by a factor of 2. The findings show the promise of using short-chain alkanes as pheromone synergists for mating disruption of insect pests of food crops. Alkane-pheromone combinations are expected to increase the competitiveness of dispensers with females, and to reduce the amount of pheromone needed for the control of these pests. © 2015 Society of Chemical Industry.
4. Transcriptome exploration of the sex pheromone gland of Lutzomyia longipalpis (Diptera: Psychodidae: Phlebotominae).
Science.gov (United States)
González-Caballero, Natalia; Valenzuela, Jesus G; Ribeiro, José M C; Cuervo, Patricia; Brazil, Reginaldo P
2013-03-07
Molecules involved in pheromone biosynthesis may represent alternative targets for insect population control. This may be particularly useful in managing the reproduction of Lutzomyia longipalpis, the main vector of the protozoan parasite Leishmania infantum in Latin America. Besides the chemical identity of the major components of the L. longipalpis sex pheromone, there is no information regarding the molecular biology behind its production. To understand this process, obtaining information on which genes are expressed in the pheromone gland is essential. In this study we used a transcriptomic approach to explore the pheromone gland and adjacent abdominal tergites in order to obtain substantial general sequence information. We used a laboratory-reared L. longipalpis (one spot, 9-Methyl GermacreneB) population, captured in Lapinha Cave, state of Minas Gerais, Brazil for this analysis. From a total of 3,547 cDNA clones, 2,502 high quality sequences from the pheromone gland and adjacent tissues were obtained and assembled into 1,387 contigs. Through blast searches of public databases, a group of transcripts encoding proteins potentially involved in the production of terpenoid precursors were identified in the 4th abdominal tergite, the segment containing the pheromone gland. Among them, protein-coding transcripts for four enzymes of the mevalonate pathway such as 3-hydroxyl-3-methyl glutaryl CoA reductase, phosphomevalonate kinase, diphosphomevalonate descarboxylase, and isopentenyl pyrophosphate isomerase were identified. Moreover, transcripts coding for farnesyl diphosphate synthase and NADP+ dependent farnesol dehydrogenase were also found in the same tergite. Additionally, genes potentially involved in pheromone transportation were identified from the three abdominal tergites analyzed. This study constitutes the first transcriptomic analysis exploring the repertoire of genes expressed in the tissue containing the L. longipalpis pheromone gland as well as the
5. Identification of pheromone-carrying protein in the preorbital gland post in the endangered Indian male Blackbuck Antelope cervicapra L.
Science.gov (United States)
Rajagopal, T; Rajkumar, R; Ponmanickam, P; Achiraman, S; Padmanabhan, P; Archunan, G
2015-12-01
In mammals, a low molecular mass protein (17-20 KDa) reported from the pheromone sources such as urine, saliva, glandular secretion, etc., as ligand-carrier (pheromone carrier) has been associated with chemo-communication. Since the preorbital gland post is one of the major pheromone sources in Indian Blackbuck, an endangered species, we assumed that it possibly contains low molecular mass protein for chemical communication. Hence, we investigated the preorbital gland post in territorial and non-territorial male blackbucks for such low molecular mass proteins adopting SDS-PAGE and LC-MS/MS analysis. The total content of protein was higher in the post of territorial males than non-territorial males of adult and sub-adult. In fact, the protein profiles such as 17, 21, 25, 42 and 61 kDa were noted in the gland secretion of territorial and non-territorial males. The intensity of the 17 kDa protein band was higher in territorial males than non-territorial males. In-gel trypsin digestion of the 17 kDa band was processed and subjected to LC-MS/MS and SEQUEST analyses. The results of LC-MS/MS and SEQUEST search showed the presence of α(2u)-globulin in the 17 kDa band. In addition, the identified α(2u)-globulin sequence possessed GDW residues, which are the characteristic signature for lipocalin family. Since the α(2u)-globulin has been reported from the pheromone-carrying proteins in some mammals, this protein may carry the volatiles (pheromone compounds) in male Blackbucks preorbital gland to evoke the scent marking for maintaining territoriality (home range) and attraction towards female, through the secretion of glandular protein.
6. Weathering the storm: how lodgepole pine trees survive mountain pine beetle outbreaks.
Science.gov (United States)
Erbilgin, Nadir; Cale, Jonathan A; Hussain, Altaf; Ishangulyyeva, Guncha; Klutsch, Jennifer G; Najar, Ahmed; Zhao, Shiyang
2017-06-01
Recent mountain pine beetle outbreaks in western North America killed millions of lodgepole pine trees, leaving few survivors. However, the mechanism underlying the ability of trees to survive bark beetle outbreaks is unknown, but likely involve phytochemicals such as monoterpenes and fatty acids that can drive beetle aggregation and colonization on their hosts. Thus, we conducted a field survey of beetle-resistant lodgepole pine (Pinus contorta) trees to retrospectively deduce whether these phytochemicals underlie their survival by comparing their chemistry to that of non-attacked trees in the same stands. We also compared beetle attack characteristics between resistant and beetle-killed trees. Beetle-killed trees had more beetle attacks and longer ovipositional galleries than resistant trees, which also lacked the larval establishment found in beetle-killed trees. Resistant trees contained high amounts of toxic and attraction-inhibitive compounds and low amounts of pheromone-precursor and synergist compounds. During beetle host aggregation and colonization, these compounds likely served three critical roles in tree survival. First, low amounts of pheromone-precursor (α-pinene) and synergist (mycrene, terpinolene) compounds reduced or prevented beetles from attracting conspecifics to residual trees. Second, high amounts of 4-allyanisole further inhibited beetle attraction to its pheromone. Finally, high amounts of toxic limonene, 3-carene, 4-allyanisole, α-linolenic acid, and linoleic acid inhibited beetle gallery establishment and oviposition. We conclude that the variation of chemotypic expression of local plant populations can have profound ecological consequences including survival during insect outbreaks.
7. Directional Bias and Pheromone for Discovery and Coverage on Networks
Energy Technology Data Exchange (ETDEWEB)
Fink, Glenn A.; Berenhaut, Kenneth S.; Oehmen, Christopher S.
2012-09-11
Natural multi-agent systems often rely on “correlated random walks” (random walks that are biased toward a current heading) to distribute their agents over a space (e.g., for foraging, search, etc.). Our contribution involves creation of a new movement and pheromone model that applies the concept of heading bias in random walks to a multi-agent, digital-ants system designed for cyber-security monitoring. We examine the relative performance effects of both pheromone and heading bias on speed of discovery of a target and search-area coverage in a two-dimensional network layout. We found that heading bias was unexpectedly helpful in reducing search time and that it was more influential than pheromone for improving coverage. We conclude that while pheromone is very important for rapid discovery, heading bias can also greatly improve both performance metrics.
8. Irradiated boll weevils: pheromone production determined by GLC analysis
International Nuclear Information System (INIS)
McGovern, W.L.; McKibben, G.H.; Gueldner, R.C.; Cross, W.H.
1975-01-01
The production of pheromone by Anthonomus grandis Boheman when treated with 10,000 rad of 60 Co gamma irradiation compared favorably with that of control weevils for 5 days; however, feeding (determined by frass collection) was reduced from day one. No direct correlation was found between production of pheromone and elimination of frass
9. 40 CFR 180.1124 - Arthropod pheromones; exemption from the requirement of a tolerance.
Science.gov (United States)
2010-07-01
... 40 Protection of Environment 23 2010-07-01 2010-07-01 false Arthropod pheromones; exemption from... FOOD Exemptions From Tolerances § 180.1124 Arthropod pheromones; exemption from the requirement of a tolerance. Arthropod pheromones, as described in § 152.25(b) of this chapter, when used in retrievably sized...
10. Male Sexual Behavior and Pheromone Emission Is Enhanced by Exposure to Guava Fruit Volatiles in Anastrepha fraterculus
Science.gov (United States)
Bachmann, Guillermo E.; Segura, Diego F.; Devescovi, Francisco; Juárez, M. Laura; Ruiz, M. Josefina; Vera, M. Teresa; Cladera, Jorge L.; Fernández, Patricia C.
2015-01-01
Background Plant chemicals can affect reproductive strategies of tephritid fruit flies by influencing sex pheromone communication and increasing male mating competitiveness. Objective and Methodology We explored whether exposure of Anastrepha fraterculus males to guava fruit volatiles and to a synthetic blend of volatile compounds released by this fruit affects the sexual performance of wild and laboratory flies. By means of bioassays and pheromone collection we investigated the mechanism underlying this phenomenon. Results Guava volatile exposure enhanced male mating success and positively affected male calling behavior and pheromone release in laboratory and wild males. Changes in male behavior appear to be particularly important during the initial phase of the sexual activity period, when most of the mating pairs are formed. Exposure of laboratory males to a subset of guava fruit volatiles enhanced mating success, showing that the response to the fruit might be mimicked artificially. Conclusions Volatiles of guava seem to influence male mating success through an enhancement of chemical and physical signals related to the communication between sexes. This finding has important implications for the management of this pest species through the Sterile Insect Technique. We discuss the possibility of using artificial blends to improve the sexual competitiveness of sterile males. PMID:25923584
11. Non-Host Plant Volatiles Disrupt Sex Pheromone Communication in a Specialist Herbivore.
Science.gov (United States)
Wang, Fumin; Deng, Jianyu; Schal, Coby; Lou, Yonggen; Zhou, Guoxin; Ye, Bingbing; Yin, Xiaohui; Xu, Zhihong; Shen, Lize
2016-09-02
The ecological effects of plant volatiles on herbivores are manifold. Little is known, however, about the impacts of non-host plant volatiles on intersexual pheromonal communication in specialist herbivores. We tested the effects of several prominent constitutive terpenoids released by conifers and Eucalyptus trees on electrophysiological and behavioral responses of an oligophagous species, Plutella xylostella, which feeds on Brassicaceae. The non-host plant volatile terpenoids adversely affected the calling behavior (pheromone emission) of adult females, and the orientation responses of adult males to sex pheromone were also significantly inhibited by these terpenoids in a wind tunnel and in the field. We suggest that disruption of both pheromone emission and orientation to sex pheromone may explain, at least in part, an observed reduction in herbivore attack in polyculture compared with monoculture plantings. We also propose that mating disruption of both male and female moths with non-host plant volatiles may be a promising alternative pest management strategy.
12. Non-Host Plant Volatiles Disrupt Sex Pheromone Communication in a Specialist Herbivore
Science.gov (United States)
Wang, Fumin; Deng, Jianyu; Schal, Coby; Lou, Yonggen; Zhou, Guoxin; Ye, Bingbing; Yin, Xiaohui; Xu, Zhihong; Shen, Lize
2016-01-01
The ecological effects of plant volatiles on herbivores are manifold. Little is known, however, about the impacts of non-host plant volatiles on intersexual pheromonal communication in specialist herbivores. We tested the effects of several prominent constitutive terpenoids released by conifers and Eucalyptus trees on electrophysiological and behavioral responses of an oligophagous species, Plutella xylostella, which feeds on Brassicaceae. The non-host plant volatile terpenoids adversely affected the calling behavior (pheromone emission) of adult females, and the orientation responses of adult males to sex pheromone were also significantly inhibited by these terpenoids in a wind tunnel and in the field. We suggest that disruption of both pheromone emission and orientation to sex pheromone may explain, at least in part, an observed reduction in herbivore attack in polyculture compared with monoculture plantings. We also propose that mating disruption of both male and female moths with non-host plant volatiles may be a promising alternative pest management strategy. PMID:27585907
13. An anti-steroidogenic inhibitory primer pheromone in male sea lamprey (Petromyzon marinus)
Science.gov (United States)
Chung-Davidson, Yu-Wen; Wang, Huiyong; Bryan, Mara B.; Wu, Hong; Johnson, Nicholas S.; Li, Weiming
2013-01-01
Reproductive functions can be modulated by both stimulatory and inhibitory primer pheromones released by conspecifics. Many stimulatory primer pheromones have been documented, but relatively few inhibitory primer pheromones have been reported in vertebrates. The sea lamprey male sex pheromone system presents an advantageous model to explore the stimulatory and inhibitory primer pheromone functions in vertebrates since several pheromone components have been identified. We hypothesized that a candidate sex pheromone component, 7α, 12α-dihydroxy-5α-cholan-3-one-24-oic acid (3 keto-allocholic acid or 3kACA), exerts priming effects through the hypothalamic-pituitary-gonadal (HPG) axis. To test this hypothesis, we measured the peptide concentrations and gene expressions of lamprey gonadotropin releasing hormones (lGnRH) and the HPG output in immature male sea lamprey exposed to waterborne 3kACA. Exposure to waterborne 3kACA altered neuronal activation markers such as jun and jun N-terminal kinase (JNK), and lGnRH mRNA levels in the brain. Waterborne 3kACA also increased lGnRH-III, but not lGnRH-I or -II, in the forebrain. In the plasma, 3kACA exposure decreased all three lGnRH peptide concentrations after 1 h exposure. After 2 h exposure, 3kACA increased lGnRHI and -III, but decreased lGnRH-II peptide concentrations in the plasma. Plasma lGnRH peptide concentrations showed differential phasic patterns. Group housing condition appeared to increase the averaged plasma lGnRH levels in male sea lamprey compared to isolated males. Interestingly, 15α-hydroxyprogesterone (15α-P) concentrations decreased after prolonged 3kACA exposure (at least 24 h). To our knowledge, this is the only known synthetic vertebrate pheromone component that inhibits steroidogenesis in males.
14. Inhibition of the Responses to Sex Pheromone of the Fall Armyworm, Spodoptera frugiperda
Science.gov (United States)
Malo, Edi A.; Rojas, Julio C.; Gago, Rafael; Guerrero, Ángel
2013-01-01
Trifluoromethyl ketones reversibly inhibit pheromone-degrading esterases in insect olfactory tissues, affecting pheromone detection and behavior of moth males. In this work, (Z)-9-tetradecenyl trifluoromethyl ketone (Z9-14:TFMK), a closely-related analogue of the pheromone of the fall armyworm, Spodoptera frugiperda (Smith) (Lepidoptera: Noctuidae), was prepared and tested in electroantennogram and field tests as possible inhibitors of the pheromone action. The electroantennogram parameters, amplitude, and the repolarization time of the antennal responses of S. frugiperda males were affected by Z9-14:TFMK vapors. Exposure of male antennae to a stream of air passing through 100 ìg of the ketone produced a significant reduction of the amplitude and an increase of 2/3 repolarization time signals to the pheromone. The effect was reversible and dose-dependent. In the field, the analogue significantly decreased the number of males caught when mixed with the pheromone in 10:1 ratio. The results suggest that Z9-14:TFMK is a mating disruptant of S. frugiperda and may be a good candidate to consider in future strategies to control this pest. PMID:24766416
15. Neurotoxicology of insecticides and pheromones
National Research Council Canada - National Science Library
Narahashi, Toshio
1979-01-01
The purpose of this symposium was to provide a forum where a variety of scientists who were interested in the interactions of insecticides and pheromones with the nervous system got together to exchange their views...
16. Aggressive reproductive competition among hopelessly queenless honeybee workers triggered by pheromone signaling
Science.gov (United States)
Malka, O.; Shnieor, S.; Katzav-Gozansky, T.; Hefetz, A.
2008-06-01
In the honeybee, Apis mellifera, the queen monopolizes reproduction, while the sterile workers cooperate harmoniously in nest maintenance. However, under queenless (QL) conditions, cooperation collapses and reproductive competition among workers ensues. This is mediated through aggression and worker oviposition, as well as shifts in pheromones, from worker to queen-like composition. Many studies suggest a dichotomy between conflict resolution through aggression or through pheromonal signaling. In this paper, we demonstrate that both phenomena comprise essential components of reproductive competition and that pheromone signaling actually triggers the onset of aggression. We kept workers as QL groups until first aggression was observed and subsequently determined the contestants’ reproductive status and content of the mandibular (MG) and Dufour’s glands (DG). In groups in which aggression occurred early, the attacked bee had consistently more queen-like pheromone in both the MG and DG, although both contestants had undeveloped ovaries. In groups with late aggression, the attacked bee had consistently larger oocytes and more queen-like pheromone in the DG, but not the MG. We suggest that at early stages of competition, the MG secretion is utilized to establish dominance and that the DG provides an honest fertility signal. We further argue that it is the higher amount of DG pheromone that triggers aggression.
17. The antibacterial protein lysozyme identified as the termite egg recognition pheromone.
Directory of Open Access Journals (Sweden)
Kenji Matsuura
Full Text Available Social insects rely heavily on pheromone communication to maintain their sociality. Egg protection is one of the most fundamental social behaviours in social insects. The recent discovery of the termite-egg mimicking fungus 'termite-ball' and subsequent studies on termite egg protection behaviour have shown that termites can be manipulated by using the termite egg recognition pheromone (TERP, which strongly evokes the egg-carrying and -grooming behaviours of workers. Despite the great scientific and economic importance, TERP has not been identified because of practical difficulties. Herein we identified the antibacterial protein lysozyme as the TERP. We isolated the target protein using ion-exchange and hydrophobic interaction chromatography, and the MALDI-TOF MS analysis showed a molecular size of 14.5 kDa. We found that the TERP provided antibacterial activity against a gram-positive bacterium. Among the currently known antimicrobial proteins, the molecular size of 14.5 kDa limits the target to lysozyme. Termite lysozymes obtained from eggs and salivary glands, and even hen egg lysozyme, showed a strong termite egg recognition activity. Besides eggs themselves, workers also supply lysozyme to eggs through frequent egg-grooming, by which egg surfaces are coated with saliva containing lysozyme. Reverse transcript PCR analysis showed that mRNA of termite lysozyme was expressed in both salivary glands and eggs. Western blot analysis confirmed that lysozyme production begins in immature eggs in queen ovaries. This is the first identification of proteinaceous pheromone in social insects. Researchers have focused almost exclusively on hydrocarbons when searching for recognition pheromones in social insects. The present finding of a proteinaceous pheromone represents a major step forward in, and result in the broadening of, the search for recognition pheromones. This novel function of lysozyme as a termite pheromone illuminates the profound influence
18. A moth pheromone brewery: production of (Z)-11-hexadecenol by heterologous co-expression of two biosynthetic genes from a noctuid moth in a yeast cell factory.
Science.gov (United States)
Hagström, Åsa K; Wang, Hong-Lei; Liénard, Marjorie A; Lassance, Jean-Marc; Johansson, Tomas; Löfstedt, Christer
2013-12-13
Moths (Lepidoptera) are highly dependent on chemical communication to find a mate. Compared to conventional unselective insecticides, synthetic pheromones have successfully served to lure male moths as a specific and environmentally friendly way to control important pest species. However, the chemical synthesis and purification of the sex pheromone components in large amounts is a difficult and costly task. The repertoire of enzymes involved in moth pheromone biosynthesis in insecta can be seen as a library of specific catalysts that can be used to facilitate the synthesis of a particular chemical component. In this study, we present a novel approach to effectively aid in the preparation of semi-synthetic pheromone components using an engineered vector co-expressing two key biosynthetic enzymes in a simple yeast cell factory. We first identified and functionally characterized a ∆11 Fatty-Acyl Desaturase and a Fatty-Acyl Reductase from the Turnip moth, Agrotis segetum. The ∆11-desaturase produced predominantly Z11-16:acyl, a common pheromone component precursor, from the abundant yeast palmitic acid and the FAR transformed a series of saturated and unsaturated fatty acids into their corresponding alcohols which may serve as pheromone components in many moth species. Secondly, when we co-expressed the genes in the Brewer's yeast Saccharomyces cerevisiae, a set of long-chain fatty acids and alcohols that are not naturally occurring in yeast were produced from inherent yeast fatty acids, and the presence of (Z)-11-hexadecenol (Z11-16:OH), demonstrated that both heterologous enzymes were active in concert. A 100 ml batch yeast culture produced on average 19.5 μg Z11-16:OH. Finally, we demonstrated that oxidized extracts from the yeast cells containing (Z)-11-hexadecenal and other aldehyde pheromone compounds elicited specific electrophysiological activity from male antennae of the Tobacco budworm, Heliothis virescens, supporting the idea that genes from different
19. A study of the female produced sex pheromone of Tenebrio molitor (Coleoptera: Tenebrionidae)
Science.gov (United States)
Mangat, Jaswinder
Mating behaviour in the yellow mealworm beetle, Tenebrio molitor , is mediated by several pheromones, including the female-produced 4-methylnonanol (4-MNol). Mating causes a decline in the titre of 4-MNol. The overall goal of this study was to determine the biochemical mechanism(s) responsible for this decline: i.e., whether the decline was due to an inhibition of pheromone biosynthesis and/or a stimulation of pheromone degradation; whether the decline was caused by the physical effect of mating or was due to the transfer of a factor from the male; and to conduct a preliminary investigation of the regulatory and signal transduction mechanisms involved in the regulation of 4-MNol production. In vitro radioassays for 4-MNol biosynthesis and degradation were developed and used to compare the levels of 4-MNol biosynthesis and degradation in virgin and mated females. Mating caused an inhibition of 4-MNol biosynthesis within 2 hours, but did not affect the rate of pheromone degradation. Decapitation of virgin females caused an inhibition of pheromone biosynthesis and did not prevent the inhibitory effect of mating. The inhibitory effect of mating was mimicked in females that were artificially inseminated with male reproductive tract homogenates (MRTH), but not in females similarly "inseminated" with water, saline, or air. Furthermore, 4-MNol biosynthesis could be inhibited in vitro by the addition of MRTH. These findings indicate that the male transferred one or more pheromonostatic factor(s) to the female during copulation that acted directly on the pheromone-producing tissue (the ovaries). In order to investigate the biochemical basis for the inhibition of pheromone biosynthesis after mating, the role of calcium was determined by modulating the level of calcium (using a calcium chelator, an ionophore, and calcium). However, due to the precipitation of calcium with the phosphate present in the buffer solution, we were unable to determine the role of calcium in the
20. A Forward Genetic Screen for Molecules Involved in Pheromone-Induced Dauer Formation in Caenorhabditis elegans
Directory of Open Access Journals (Sweden)
Scott J. Neal
2016-05-01
Full Text Available Animals must constantly assess their surroundings and integrate sensory cues to make appropriate behavioral and developmental decisions. Pheromones produced by conspecific individuals provide critical information regarding environmental conditions. Ascaroside pheromone concentration and composition are instructive in the decision of Caenorhabditis elegans to either develop into a reproductive adult or enter into the stress-resistant alternate dauer developmental stage. Pheromones are sensed by a small set of sensory neurons, and integrated with additional environmental cues, to regulate neuroendocrine signaling and dauer formation. To identify molecules required for pheromone-induced dauer formation, we performed an unbiased forward genetic screen and identified phd (pheromone response-defective dauer mutants. Here, we describe new roles in dauer formation for previously identified neuronal molecules such as the WD40 domain protein QUI-1 and MACO-1 Macoilin, report new roles for nociceptive neurons in modulating pheromone-induced dauer formation, and identify tau tubulin kinases as new genes involved in dauer formation. Thus, phd mutants define loci required for the detection, transmission, or integration of pheromone signals in the regulation of dauer formation.
1. Excavation and aggregation as organizing factors in de novo construction by mound-building termites.
Science.gov (United States)
Green, Ben; Bardunias, Paul; Turner, J Scott; Nagpal, Radhika; Werfel, Justin
2017-06-14
Termites construct complex mounds that are orders of magnitude larger than any individual and fulfil a variety of functional roles. Yet the processes through which these mounds are built, and by which the insects organize their efforts, remain poorly understood. The traditional understanding focuses on stigmergy, a form of indirect communication in which actions that change the environment provide cues that influence future work. Termite construction has long been thought to be organized via a putative 'cement pheromone': a chemical added to deposited soil that stimulates further deposition in the same area, thus creating a positive feedback loop whereby coherent structures are built up. To investigate the detailed mechanisms and behaviours through which termites self-organize the early stages of mound construction, we tracked the motion and behaviour of major workers from two Macrotermes species in experimental arenas. Rather than a construction process focused on accumulation of depositions, as models based on cement pheromone would suggest, our results indicated that the primary organizing mechanisms were based on excavation. Digging activity was focused on a small number of excavation sites, which in turn provided templates for soil deposition. This behaviour was mediated by a mechanism of aggregation, with termites being more likely to join in the work at an excavation site as the number of termites presently working at that site increased. Statistical analyses showed that this aggregation mechanism was a response to active digging, distinct from and unrelated to putative chemical cues that stimulate deposition. Agent-based simulations quantitatively supported the interpretation that the early stage of de novo construction is primarily organized by excavation and aggregation activity rather than by stigmergic deposition. © 2017 The Author(s).
2. Genetic dissection of pheromone processing reveals main olfactory system-mediated social behaviors in mice.
Science.gov (United States)
Matsuo, Tomohiko; Hattori, Tatsuya; Asaba, Akari; Inoue, Naokazu; Kanomata, Nobuhiro; Kikusui, Takefumi; Kobayakawa, Reiko; Kobayakawa, Ko
2015-01-20
Most mammals have two major olfactory subsystems: the main olfactory system (MOS) and vomeronasal system (VNS). It is now widely accepted that the range of pheromones that control social behaviors are processed by both the VNS and the MOS. However, the functional contributions of each subsystem in social behavior remain unclear. To genetically dissociate the MOS and VNS functions, we established two conditional knockout mouse lines that led to either loss-of-function in the entire MOS or in the dorsal MOS. Mice with whole-MOS loss-of-function displayed severe defects in active sniffing and poor survival through the neonatal period. In contrast, when loss-of-function was confined to the dorsal MOB, sniffing behavior, pheromone recognition, and VNS activity were maintained. However, defects in a wide spectrum of social behaviors were observed: attraction to female urine and the accompanying ultrasonic vocalizations, chemoinvestigatory preference, aggression, maternal behaviors, and risk-assessment behaviors in response to an alarm pheromone. Functional dissociation of pheromone detection and pheromonal induction of behaviors showed the anterior olfactory nucleus (AON)-regulated social behaviors downstream from the MOS. Lesion analysis and neural activation mapping showed pheromonal activation in multiple amygdaloid and hypothalamic nuclei, important regions for the expression of social behavior, was dependent on MOS and AON functions. Identification of the MOS-AON-mediated pheromone pathway may provide insights into pheromone signaling in animals that do not possess a functional VNS, including humans.
3. Recent development in insect pheromone research, in particular in the Netherlands
NARCIS (Netherlands)
Ritter, F.J.; Persoons, C.J.
1975-01-01
A review is given of recent pheromone work carried out in the Netherlands on Lepidoptera, cockroaches, pharaoh's ants and termites, special emphasis being given to isolation and identification aspects. The sex pheromones of three leaf roller moths (Tortricidae) have been isolated, identified and
4. Assessment of pheromone production and response in fission yeast by a halo test of induced sporulation
DEFF Research Database (Denmark)
Egel, R; Willer, M; Kjaerulff, S
1994-01-01
We describe a rapid, sensitive and semi-quantitative plate assay for monitoring pheromone activity in the fission yeast Schizosaccharomyces pombe. It is based on the observation that meiosis requires stimulation by pheromone and exploits diploid strains that will only sporulate after addition...... of exogenous pheromone. The tester strains are heterozygous for mating type, are non-switching, and are mutated in one of the early subfunctions (either mat1-Mc or mat1-Pc), so that meiosis is only induced after exposure to exogenous pheromone (M-factor or P-factor, respectively). Pheromone activity...
5. A pheromone analogue affects the evaporation rate of (+)-disparlure in Lymantria dispar.
Science.gov (United States)
Sollai, Giorgia; Murgia, Sergio; Secci, Francesco; Frongia, Angelo; Cerboneschi, Anna; Masala, Carla; Liscia, Anna; Crnjar, Roberto; Solari, Paolo
2014-04-01
The gypsy moth Lymantria dispar L. is a widespread pest that causes economic damage to cork oak forests. Females produce the sex pheromone (+)-(7R,8S)-epoxy-2-methyloctadecane, known as (+)-disparlure [(+)D], for long-distance attraction of conspecific males. A (+)D analogue, 2-decyl-1-oxaspiro[2.2]pentane (OXP-01), neither stimulating nor attractive by itself, causes short-time inhibition of male response in a 1:1 blend with (+)D. The authors investigated whether and how the biological activity of the natural pheromone is affected by OXP-01 on a long-time basis (up to 16 days), also by looking at possible physicochemical reciprocal interactions. Blending of (+)D with OXP-01 decreased, under low evaporation rate, the pheromone effectiveness, as assessed by electroantennogram recordings. In male trappings, within the first 24 h, OXP-01 decreased and later enhanced the blend attractiveness, but only under high evaporation rate. Gas chromatography-mass spectroscopy indicates that quantitative retrieval of (+)D from blend cartridges is higher than for pure pheromone, and nuclear magnetic resonance measurements show that OXP-01 produces, possibly by Van der Waals interactions, a bimolecular entity with pheromone causing retention and lengthening of its attractiveness over time. The biological and physicochemical interactions between (+)D and OXP-01 may provide valuable information for the optimisation of pheromone-based control strategies for gypsy moths. © 2013 Society of Chemical Industry.
6. Genome-wide identification of pheromone-targeted transcrption in fission yeast
DEFF Research Database (Denmark)
Xue-Franzen, Y.; Kjærulff, S.; Holmberg, C.
2006-01-01
Background Fission yeast cells undergo sexual differentiation in response to nitrogen starvation. In this process haploid M and P cells first mate to form diploid zygotes, which then enter meiosis and sporulate. Prior to mating, M and P cells communicate with diffusible mating pheromones that act......Background Fission yeast cells undergo sexual differentiation in response to nitrogen starvation. In this process haploid M and P cells first mate to form diploid zygotes, which then enter meiosis and sporulate. Prior to mating, M and P cells communicate with diffusible mating pheromones...... transcription factor is responsible for the majority of pheromone-induced transcription. Finally, most cell-type specific genes now appear to be identified in fission yeast....
7. Sex pheromone receptor proteins. Visualization using a radiolabeled photoaffinity analog
International Nuclear Information System (INIS)
Vogt, R.G.; Prestwich, G.D.; Riddiford, L.M.
1988-01-01
A tritium-labeled photoaffinity analog of a moth pheromone was used to covalently modify pheromone-selective binding proteins in the antennal sensillum lymph and sensory dendritic membranes of the male silk moth, Antheraea polyphemus. This analog, (E,Z)-6,11-[ 3 H]hexadecadienyl diazoacetate, allowed visualization of a 15-kilodalton soluble protein and a 69-kilodalton membrane protein in fluorescence autoradiograms of electrophoretically separated antennal proteins. Covalent modification of these proteins was specifically reduced when incubation and UV irradiation were conducted in the presence of excess unlabeled pheromone, (E,Z)-6,11-hexadecadienyl acetate. These experiments constitute the first direct evidence for a membrane protein of a chemosensory neuron interacting in a specific fashion with a biologically relevant odorant
8. Interference of plant volatiles on pheromone receptor neurons of male Grapholita molesta (Lepidoptera: Tortricidae).
Science.gov (United States)
Ammagarahalli, Byrappa; Gemeno, César
2015-10-01
In moths, sex pheromone components are detected by pheromone-specific olfactory receptor neurons (ph-ORNs) housed in sensilla trichodea in the male antennae. In Grapholita molesta, ph-ORNs are highly sensitive and specific to the individual sex pheromone components, and thus help in the detection and discrimination of the unique conspecific pheromone blend. Plant odors interspersed with a sub-optimal pheromone dose are reported to increase male moth attraction. To determine if the behavioral synergism of pheromone and plant odors starts at the ph-ORN level, single sensillum recordings were performed on Z8-12:Ac and E8-12:Ac ph-ORNs (Z-ORNs and E-ORNs, respectively) stimulated with pheromone-plant volatile mixtures. First, biologically meaningful plant-volatile doses were determined by recording the response of plant-specific ORNs housed in sensilla auricillica and trichodea to several plant odorants. This exploration provided a first glance at plant ORNs in this species. Then, using these plant volatile doses, we found that the spontaneous activity of ph-ORNs was not affected by the stimulation with plant volatiles, but that a binary mixture of sex pheromone and plant odorants resulted in a small (about 15%), dose-independent, but statistically significant, reduction in the spike frequency of Z-ORNs with respect to stimulation with Z8-12:Ac alone. The response of E-ORNs to a combination of E8-12:Ac and plant volatiles was not different from E8-12:Ac alone. We argue that the small inhibition of Z-ORNs caused by physiologically realistic plant volatile doses is probably not fully responsible for the observed behavioral synergism of pheromone and plant odors. Copyright © 2015 Elsevier Ltd. All rights reserved.
9. Variation in courtship ultrasounds of three Ostrinia moths with different sex pheromones
DEFF Research Database (Denmark)
Takanashi, Takuma; Nakano, Ryo; Surlykke, Annemarie
2010-01-01
energy at 40 kHz, but distinctly different from the ultrasound produced by O. furnacalis, consisting of groups of pulses peaking at 50 kHz and with substantially more energy up to 80 kHz. Despite overall similarities, temporal features and patterns of amplitude modulation differed significantly among...... the geographic populations of O. nubilalis and O. scapulalis, which differed in pheromone type. In contrast, no significant difference in hearing was found among the three species with regard to the most sensitive frequencies and hearing threshold levels. The patterns of variations in the songs and pheromones...... well reflected those of the phylogenetic relationships, implying that ultrasound and pheromone communications have diverged concordantly. Our results suggest that concordant evolution in sexual signals such as courtship ultrasounds and sex pheromones occurs in moths....
10. THE USE OF GRIGNARD REAGENT IN PHEROMONE SYNTHESIS FOR PALM WEEVIL (Rhynchorus, Sp
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Warsito Warsito
2010-06-01
Full Text Available In an integrated controlling system of palm weevil, using of synthetic feromoid is strickly needed. The research is aimed to synthesize pheromone which secreted by the weevil, e.g. 4-methyl-5-nonanol (R. ferrugineus and 3-methyl-4-octanol (R. schach through Grignard reagent which formed in situ. The synthesis was proceded by retrosynthesis to determine the precursor, valeraldehyde. The precursor was reacted with Grignard reagent of sec-amyl magnesium bromide (R. ferrugenieus and sec-butyl magnesium bromide (R. shach which made in situ. Characterization of the synthetic molecular pheromone was performed by Gas Chromatography-mass spectroscopy and Fourier Transformed Infra Red. The bioassay of the molecule was carried out by olfactometer. The result showed that the conversion of the reactions were 51.28% (4-methyl-5-nonanol and 85.90% (3-methyl-4-octanol. The character of physico-chemical and bioactivity of the synthetic pheromone are identic with natural pheromones. Keywords: palm weevil, pheromone, grignard reagent
11. Allelic exchange of pheromones and their receptors reprograms sexual identity in Cryptococcus neoformans.
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Brynne C Stanton
2010-02-01
Full Text Available Cell type specification is a fundamental process that all cells must carry out to ensure appropriate behaviors in response to environmental stimuli. In fungi, cell identity is critical for defining "sexes" known as mating types and is controlled by components of mating type (MAT loci. MAT-encoded genes function to define sexes via two distinct paradigms: 1 by controlling transcription of components common to both sexes, or 2 by expressing specially encoded factors (pheromones and their receptors that differ between mating types. The human fungal pathogen Cryptococcus neoformans has two mating types (a and alpha that are specified by an extremely unusual MAT locus. The complex architecture of this locus makes it impossible to predict which paradigm governs mating type. To identify the mechanism by which the C. neoformans sexes are determined, we created strains in which the pheromone and pheromone receptor from one mating type (a replaced the pheromone and pheromone receptor of the other (alpha. We discovered that these "alpha(a" cells effectively adopt a new mating type (that of a cells; they sense and respond to alpha factor, they elicit a mating response from alpha cells, and they fuse with alpha cells. In addition, alpha(a cells lose the alpha cell type-specific response to pheromone and do not form germ tubes, instead remaining spherical like a cells. Finally, we discovered that exogenous expression of the diploid/dikaryon-specific transcription factor Sxi2a could then promote complete sexual development in crosses between alpha and alpha(a strains. These data reveal that cell identity in C. neoformans is controlled fully by three kinds of MAT-encoded proteins: pheromones, pheromone receptors, and homeodomain proteins. Our findings establish the mechanisms for maintenance of distinct cell types and subsequent developmental behaviors in this unusual human fungal pathogen.
12. Allelic exchange of pheromones and their receptors reprograms sexual identity in Cryptococcus neoformans.
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Stanton, Brynne C; Giles, Steven S; Staudt, Mark W; Kruzel, Emilia K; Hull, Christina M
2010-02-26
Cell type specification is a fundamental process that all cells must carry out to ensure appropriate behaviors in response to environmental stimuli. In fungi, cell identity is critical for defining "sexes" known as mating types and is controlled by components of mating type (MAT) loci. MAT-encoded genes function to define sexes via two distinct paradigms: 1) by controlling transcription of components common to both sexes, or 2) by expressing specially encoded factors (pheromones and their receptors) that differ between mating types. The human fungal pathogen Cryptococcus neoformans has two mating types (a and alpha) that are specified by an extremely unusual MAT locus. The complex architecture of this locus makes it impossible to predict which paradigm governs mating type. To identify the mechanism by which the C. neoformans sexes are determined, we created strains in which the pheromone and pheromone receptor from one mating type (a) replaced the pheromone and pheromone receptor of the other (alpha). We discovered that these "alpha(a)" cells effectively adopt a new mating type (that of a cells); they sense and respond to alpha factor, they elicit a mating response from alpha cells, and they fuse with alpha cells. In addition, alpha(a) cells lose the alpha cell type-specific response to pheromone and do not form germ tubes, instead remaining spherical like a cells. Finally, we discovered that exogenous expression of the diploid/dikaryon-specific transcription factor Sxi2a could then promote complete sexual development in crosses between alpha and alpha(a) strains. These data reveal that cell identity in C. neoformans is controlled fully by three kinds of MAT-encoded proteins: pheromones, pheromone receptors, and homeodomain proteins. Our findings establish the mechanisms for maintenance of distinct cell types and subsequent developmental behaviors in this unusual human fungal pathogen.
13. Refining the dual olfactory hypothesis: pheromone reward and odour experience.
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Martínez-García, Fernando; Martínez-Ricós, Joana; Agustín-Pavón, Carmen; Martínez-Hernández, Jose; Novejarque, Amparo; Lanuza, Enrique
2009-06-25
In rodents, sexual advertisement and gender recognition are mostly (if not exclusively) mediated by chemosignals. Specifically, there is ample evidence indicating that female mice are 'innately' attracted by male sexual pheromones that have critical non-volatile components and are detected by the vomeronasal organ. These pheromones can only get access to the vomeronasal organ by active pumping mechanisms that require close contact with the source of the stimulus (e.g. urine marks) during chemoinvestigation. We have hypothesised that male sexual pheromones are rewarding to female mice. Indeed, male-soiled bedding can be used as a reinforcer to induce conditioned place preference, provided contact with the bedding is allowed. The neural mechanisms of pheromone reward seem, however, different from those employed by other natural reinforcers, such as the sweetness or postingestive effects of sucrose. In contrast to vomeronasal-detected male sexual pheromones, male-derived olfactory stimuli (volatiles) are not intrinsically attractive to female mice. However, after repeated exposure to male-soiled bedding, intact female mice develop an acquired preference for male odours. On the contrary, in females whose accessory olfactory bulbs have been lesioned, exposure to male-soiled bedding induces aversion to male odorants. These considerations, together with data on the different properties of olfactory and vomeronasal receptors, lead us to make a proposal for the complementary roles that the olfactory and vomeronasal systems play in intersexual attraction and in other forms of intra- or inter-species communication.
14. Queen pheromones: The chemical crown governing insect social life.
Science.gov (United States)
Holman, Luke
2010-11-01
Group-living species produce signals that alter the behavior and even the physiology of their social partners. Social insects possess especially sophisticated chemical communication systems that govern every aspect of colony life, including the defining feature of eusociality: reproductive division of labor. Current evidence hints at the central importance of queen pheromones, but progress has been hindered by the fact that such pheromones have only been isolated in honeybees. In a pair of papers on the ant Lasius niger, we identified and investigated a queen pheromone regulating worker sterility. The cuticular hydrocarbon 3-methylhentriacontane (3-MeC(31)) is correlated with queen maturity and fecundity and workers are also more likely to execute surplus queens that have low amounts of this chemical. Experiments with synthetic 3-MeC(31) found that it inhibits ovarian development in queenless workers and lowers worker aggression towards objects coated with it. Production of 3-MeC(31) by queens was depressed by an experimental immune challenge, and the same chemical was abundant on queenlaid eggs, suggesting that the workers' responses to the queen are conditional on her health and fecundity. Together with other studies, these results indicate that queen pheromones are honest signals of quality that simultaneously regulate multiple social behaviors.
15. Ready for a fight? The physiological effects of detecting an opponent's pheromone cues prior to a contest.
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Garcia, Mark J; Williams, John; Sinderman, Benjamin; Earley, Ryan L
2015-10-01
Reception of pheromone cues can elicit significant physiological (e.g. steroid hormone levels) changes in the recipient. These pheromone-induced physiological changes have been well documented for male-female interactions, but scarcely in same-sex interactions (male-male and female-female). We sought to address this dearth in the current literature and examine whether mangrove rivulus fish (Kryptolebias marmoratus) could detect and, ultimately, mount a physiological response to the pheromone signature of a potential, same-sex competitor. We examined steroid hormone levels in mangrove rivulus exposed to one of three treatments: 1) isolation, 2) exposure to pheromones of a size-matched partner, and 3) pheromone exposure to a size-matched opponent followed by a physical encounter with the opponent. We found that exposure to a competitor's pheromone cues elicited a significant increase in testosterone levels. Increases in testosterone were similar across genetically distinct lineages derived from geographically distinct populations. Further, testosterone levels were similar between individuals only exposed to pheromone cues and individuals exposed to both pheromone cues and a subsequent physical encounter. Our findings led us to generate a number of testable predictions regarding how mangrove rivulus utilize pheromone signals in social interactions, the molecular mechanisms linking social stimuli and hormonal responses, and the possible adaptive benefits of hormonal responsiveness to receiving a potential competitor's pheromone cues. Copyright © 2015 Elsevier Inc. All rights reserved.
16. Identification and behavioral evaluation of sex pheromone components of the Chinese pine caterpillar moth, Dendrolimus tabulaeformis.
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Xiang-Bo Kong
Full Text Available BACKGROUND: The Chinese pine caterpillar moth, Dendrolimus tabulaeformis Tsai and Liu (Lepidoptera: Lasiocampidae is the most important defoliator of coniferous trees in northern China. Outbreaks occur over enormous areas and often lead to the death of forests during 2-3 successive years of defoliation. The sex pheromone of D. tabulaeformis was investigated to define its chemistry and behavioral activity. METHODOLOGY/PRINCIPAL FINDINGS: Sex pheromone was collected from calling female D. tabulaeformis by headspace solid phase microextraction (SPME and by solvent extraction of pheromone glands. Extracts were analyzed by coupled gas chromatography/mass spectrometry (GC-MS and coupled GC-electroantennographic detection (GC-EAD, using antennae from male moths. Five components from the extracts elicited antennal responses. These compounds were identified by a combination of retention indices, electron impact mass spectral matches, and derivatization as (Z-5-dodecenyl acetate (Z5-12:OAc, (Z-5-dodecenyl alcohol (Z5-12:OH, (5Z,7E-5,7-dodecadien-1-yl acetate (Z5,E7-12:OAc, (5Z,7E-5,7-dodecadien-1-yl propionate (Z5,E7-12:OPr, and (5Z,7E-5,7-dodecadien-1-ol (Z5,E7-12:OH. Behavioral assays showed that male D. tabulaeformis strongly discriminated against incomplete and aberrant blend ratios. The correct ratio of Z5,E7-12:OAc, Z5,E7-12:OH, and Z5,E7-12:OPr was essential for optimal upwind flight and source contact. The two monoenes, Z5-12:OAc and Z5-12:OH, alone or binary mixtures, had no effect on behavioral responses when added to the optimal three-component blend. CONCLUSIONS/SIGNIFICANCE: The fact that deviations from the optimal ratio of 100:100:4.5 of Z5,E7-12:OAc, Z5,EZ7-12:OH, and Z5,E7-12:OPr resulted in marked decreases in male responses suggests that biosynthesis of the pheromone components is precisely controlled. The optimal blend of the sex pheromone components of D. tabulaeformis worked out in this study should find immediate use in monitoring
17. Pheromone application in prevention and therapy of domestic animal behavioral disorder
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Vučinić Marijana
2007-01-01
Full Text Available This review-type paper presents the latest knowledge on pheromone therapy. Pheromone therapy does not imply merely the use of structural analogues of pheromones in therapy, but also in the prevention of behavioral disorders in domestic animals. Their application is induced in all cases in which the effects of stressors are expected and their negative effect on the health condition, welfare and production results of domestic animals. Structural analogues of pheromones can successfully be applied in the prevention and therapy of behavioral disorders in horses, swine, dogs, and cats. Recent investigations have confirmed that structural analogues of semiochemicals exert a positive effect also on the production results and meat quality of broilers. They realize their therapeutic and preventive effect on the behavior of domestic animals through the stabilization of the emotional state, relaxation, and calming the animals that are disturbed, or could become disturbed due to the effect of stressors.
18. Pheromone-Based Pest Management in China: Past, Present, and Future Prospects.
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Cui, Gen Zhong; Zhu, Junwei Jerry
2016-07-01
Semiochemical-based pest management technology has been widely used to monitor and control insect pests in agricultural, forestry, and public health sectors in the western world. It became a popular tool in the early 1970s with tremendous efforts in developing environment-friendly control technologies for the integrated pest management. However, in China, similar research lagged 15 to 20 years and was not initiated until the late 1980s. In this review, we present the early history of pheromone research that has led to the current practical applications in China, particularly in the development of pheromone-based pest management products. We also provide information regarding the current status of pheromone-based product manufacturing, marketing, and regulatory issues related to local semiochemical industries, which may be useful to other international companies interested in pursuing business in China. In addition, we share some research topics that represent new directions of the present pheromone research to explore novel tools for advancing semiochemical-based pest management in China.
19. Foragers of sympatric Asian honey bee species intercept competitor signals by avoiding benzyl acetate from Apis cerana alarm pheromone.
Science.gov (United States)
Wen, Ping; Cheng, Yanan; Qu, Yufeng; Zhang, Hongxia; Li, Jianjun; Bell, Heather; Tan, Ken; Nieh, James
2017-07-27
While foraging, animals can form inter- and intraspecific social signalling networks to avoid similar predators. We report here that foragers of different native Asian honey bee species can detect and use a specialized alarm pheromone component, benzyl acetate (BA), to avoid danger. We analysed the volatile alarm pheromone produced by attacked workers of the most abundant native Asian honey bee, Apis cerana and tested the responses of other bee species to these alarm signals. As compared to nest guards, A. cerana foragers produced 3.38 fold higher levels of BA. In foragers, BA and (E)-dec-2-en-1-yl acetate (DA) generated the strongest antennal electrophysiological responses. BA was also the only compound that alerted flying foragers and inhibited A. cerana foraging. BA thereby decreased A. cerana foraging for risky sites. Interestingly, although BA occurs only in trace amounts and is nearly absent in sympatric honeybee species (respectively only 0.07% and 0.44% as much in A. dorsata and A. florea), these floral generalists detected and avoided BA as strongly as they did to their own alarm pheromone on natural inflorescences. These results demonstrate that competing pollinators can take advantage of alarm signal information provided by other species.
20. Different bioassays for investigating orientation responses of the banana weevil, Cosmopolites sordidus, show additive effects of host plant volatiles and a synthetic male-produced aggregation pheromone
NARCIS (Netherlands)
Tinzaara, W.; Dicke, M.; Huis, van A.; Loon, van J.A.; Gold, C.S.
2003-01-01
Three different bioassay methods to investigate the orientation behaviour of the banana weevil, Cosmopolites sordidus (Germar) (Coleoptera: Curculionidae), to host plant volatiles and a synthetic pheromone (cosmolure+) were compared. A locomotion compensator was used to separately record walking
1. Sex pheromones of the southern armyworm moth: isolation, identification, and synthesis.
Science.gov (United States)
Jacobson, M; Redfern, R E; Jones, W A; Aldridge, M H
1970-10-30
Two sex pheromones have been isolated from the female southern armyworm moth, Prodenia eridania (Cramer), and identified as cis-9-tetradecen-1-ol acetate, identical with the sex pheromone of the fall armyworm moth, Spodoptera frugiperda (J. E. Smith), and cis-9,trans-12-tetradecadien-1-ol acetate.
2. The ras1 function of Schizosaccharomyces pombe mediates pheromone-induced transcription
DEFF Research Database (Denmark)
Nielsen, O; Davey, William John; Egel, R
1992-01-01
Loss of ras1+ function renders fission yeast cells unable to undergo morphological changes in response to mating pheromones, whereas cells carrying activated mutations in ras1 are hyper-responsive. This has led to the suggestion that the ras1 gene product plays a role in mating pheromone signal...
3. Monitoring Pseudococcus calceolariae (Hemiptera: Pseudococcidae) in Fruit Crops Using Pheromone-Baited Traps.
Science.gov (United States)
Flores, M Fernanda; Romero, Alda; Oyarzun, M Soledad; Bergmann, Jan; Zaviezo, Tania
2015-10-01
The citrophilus mealybug, Pseudococcus calceolariae (Maskell), is an important pest of fruit crops in many regions of the world. Recently, its sex pheromone has been identified and synthesized. We carried out field experiments with the goal of developing monitoring protocols for P. calceolariae using pheromone-baited traps. Traps checked hourly for 24 hours showed a distinct diel pattern of male flight, between 18:00 and 21:00 h. The presence of unnatural stereoisomers did not affect trap captures, with isomeric mixtures capturing similar amounts of males as the biological active isomer. Dose of isomeric mixture pheromone (0-100 µg) had a nonlinear effect on male captures, with 10, 30, and 50 µg capturing similar amounts. The effective range of pheromone traps was determined by placing traps at different distances (15, 40, and 80 m) from an infested blueberry field, loaded with 0, 1 and 25 µg of the pheromone. For all distances, 25 µg dose captured more males, and was highly attractive up to 40 m. There was a significant effect of lure age on male captures (0-150 d), with similar amount of males captured up to 90-day-old lure, and lower captures in the 150-day-old lure compared with fresh ones. We found significant positive correlations between P. calceolariae males caught in pheromone traps with female abundance and fruit infestation at harvest. Our results show the usefulness of P. calceolariae pheromones for monitoring at field level and provide information for the design of monitoring protocols. © The Authors 2015. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For Permissions, please email: journals.permissions@oup.com.
4. Courtship Pheromone Use in a Model Urodele, the Mexican Axolotl (Ambystoma mexicanum).
Science.gov (United States)
Maex, Margo; Van Bocxlaer, Ines; Mortier, Anneleen; Proost, Paul; Bossuyt, Franky
2016-02-04
Sex pheromones have been shown to constitute a crucial aspect of salamander reproduction. Until now, courtship pheromones of Salamandridae and Plethodontidae have been intensively studied, but information on chemical communication in other urodelan families is essentially lacking. The axolotl (Ambystoma mexicanum, Ambystomatidae) has a courtship display that suggests a key role for chemical communication in the orchestration of its sexual behavior, but no sex pheromones have yet been characterized from this species. Here we combined whole transcriptome analyses of the male cloaca with proteomic analyses of water in which axolotls were allowed to court to show that male axolotls secrete multiple ca. 20 kDa glycosylated sodefrin precursor-like factor (SPF) proteins during courtship. In combination with phylogenetic analyses, our data show that the male cloaca essentially secretes a courtship-specific clade of SPF proteins that is orthologous to salamandrid courtship pheromones. In addition, we identified an SPF protein for which no orthologs have been described from other salamanders so far. Overall, our study advocates a central role for SPF proteins during the courtship display of axolotls and adds knowledge on pheromone use in a previously unexplored deep evolutionary branch of salamander evolution.
5. Age-related and Individual Variation in Male Piezodorus hybneri (Heteroptera: Pentatomidae Pheromones
Directory of Open Access Journals (Sweden)
2012-01-01
Full Text Available Males of the Piezodorus hybneri stink bug produce a pheromone comprising β-sesquiphellandrene (Sesq, (R-15-hexadecanolide (R15, and methyl (Z-8-hexadecenoate (Z8. We collected airborne volatiles from individual P. hybneri males and analyzed them by GC-MS. Daily analysis from 1 to 16 days after adult emergence showed that pheromone emission started around 3 to 6 days after adult emergence and peaked (~1 μg/male/day on day 11. The proportion of Sesq tended to increase with age to about 80% on days 12 to 16. On the other hand, the proportion of R15 tended to decrease with age. The proportion of Z8 reached a maximum of about 34% on day 9 but otherwise remained below 20%. The total amount of pheromone emitted by individual males varied considerably: three males emitted more than 10 μg, whereas another three males emitted little or no pheromone and failed to survive by the end of the experiment. These results suggest that the amount of P. hybneri pheromone and its blend ratio could be affected by the male’s physical conditions, such as vitality and age.
6. The Effect of Trail Pheromone and Path Confinement on Learning of Complex Routes in the Ant Lasius niger.
Science.gov (United States)
Czaczkes, Tomer J; Weichselgartner, Tobias; Bernadou, Abel; Heinze, Jürgen
2016-01-01
Route learning is key to the survival of many central place foragers, such as bees and many ants. For ants which lay pheromone trails, the presence of a trail may act as an important source of information about whether an error has been made. The presence of trail pheromone has been demonstrated to support route learning, and the effect of pheromones on route choice have been reported to persist even after the pheromones have been removed. This could be explained in two ways: the pheromone may constrain the ants onto the correct route, thus preventing errors and aiding learning. Alternatively, the pheromones may act as a 'reassurance', signalling that the learner is on the right path and that learning the path is worthwhile. Here, we disentangle pheromone presence from route confinement in order to test these hypotheses, using the ant Lasius niger as a model. Unexpectedly, we did not find any evidence that pheromones support route learning. Indeed, there was no evidence that ants confined to the correct route learned at all. Thus, while we cannot support the 'reassurance' hypothesis, we can rule out the 'confinement' hypothesis. Other findings, such as a reduction in pheromone deposition in the presence of trail pheromones, are remarkably consistent with previous experiments. As previously reported, ants which make errors on their outward journey upregulate pheromone deposition on their return. Surprisingly, ants which would go on to make an error down-regulate pheromone deposition on their outward journey, hinting at a capacity for ants to gauge the quality of their own memories.
7. The Effect of Trail Pheromone and Path Confinement on Learning of Complex Routes in the Ant Lasius niger.
Directory of Open Access Journals (Sweden)
Tomer J Czaczkes
Full Text Available Route learning is key to the survival of many central place foragers, such as bees and many ants. For ants which lay pheromone trails, the presence of a trail may act as an important source of information about whether an error has been made. The presence of trail pheromone has been demonstrated to support route learning, and the effect of pheromones on route choice have been reported to persist even after the pheromones have been removed. This could be explained in two ways: the pheromone may constrain the ants onto the correct route, thus preventing errors and aiding learning. Alternatively, the pheromones may act as a 'reassurance', signalling that the learner is on the right path and that learning the path is worthwhile. Here, we disentangle pheromone presence from route confinement in order to test these hypotheses, using the ant Lasius niger as a model. Unexpectedly, we did not find any evidence that pheromones support route learning. Indeed, there was no evidence that ants confined to the correct route learned at all. Thus, while we cannot support the 'reassurance' hypothesis, we can rule out the 'confinement' hypothesis. Other findings, such as a reduction in pheromone deposition in the presence of trail pheromones, are remarkably consistent with previous experiments. As previously reported, ants which make errors on their outward journey upregulate pheromone deposition on their return. Surprisingly, ants which would go on to make an error down-regulate pheromone deposition on their outward journey, hinting at a capacity for ants to gauge the quality of their own memories.
8. REPRODUCTIVE CHARACTER DISPLACEMENT OF EPICUTICULAR COMPOUNDS AND THEIR CONTRIBUTION TO MATE CHOICE IN DROSOPHILA SUBQUINARIA AND DROSOPHILA RECENS
Science.gov (United States)
Dyer, Kelly A.; White, Brooke E.; Sztepanacz, Jacqueline L.; Bewick, Emily R.; Rundle, Howard D.
2014-01-01
Interactions between species can alter selection on sexual displays used in mate choice within species. Here we study the epicuticular pheromones of two Drosophila species that overlap partially in geographic range and are incompletely reproductively isolated. Drosophila subquinaria shows a pattern of reproductive character displacement against Drosophila recens, and partial behavioral isolation between conspecific sympatric versus allopatric populations, whereas D. recens shows no such variation in mate choice. First, using manipulative perfuming experiments, we show that females use pheromones as signals for mate discrimination both between species and among populations of D. subquinaria. Second, we show that patterns of variation in epicuticular compounds, both across populations and between species, are consistent with those previously shown for mating probabilities: pheromone compositions differ between populations of D. subquinaria that are allopatric versus sympatric with D. recens, but are similar across populations of D. recens regardless of overlap with D. subquinaria. We also identify differences in pheromone composition among allopatric regions of D. subquinaria. In sum, our results suggest that epicuticular compounds are key signals used by females during mate recognition, and that these traits have diverged among D. subquinaria populations in response to reinforcing selection generated by the presence of D. recens. PMID:24351014
9. Different roles suggested by sex-biased expression and pheromone binding affinity among three pheromone binding proteins in the pink rice borer, Sesamia inferens (Walker) (Lepidoptera: Noctuidae).
Science.gov (United States)
Jin, Jun-Yan; Li, Zhao-Qun; Zhang, Ya-Nan; Liu, Nai-Yong; Dong, Shuang-Lin
2014-07-01
Pheromone binding proteins (PBPs) are thought to bind and transport hydrophobic sex pheromone molecules across the aqueous sensillar lymph to specific pheromone receptors on the dendritic membrane of olfactory neurons. A maximum of 3 PBP genes have been consistently identified in noctuid species, and each of them shares high identity with its counterparts in other species within the family. The functionality differences of the 3 proteins are poorly understood. In the present study, 3 PBP cDNAs (SinfPBP1, 2, 3) were identified from the pink rice borer, Sesamia inferens, for the first time. The quantitative real-time PCR indicated that the 3 PBPs displayed similar temporal but very different sex related expression profiles. Expression of SinfPBP1 and SinfPBP2 were highly and moderately male biased, respectively, while SinfPBP3 was slightly female biased, as SinfPBPs were expressed at very different levels (PBP1>PBP2≫PBP3) in male antennae, but at similar levels in female antennae. Furthermore, the 3 SinfPBPs displayed different ligand binding profiles in fluorescence competitive binding assays. SinfPBP1 exhibited high and similar binding affinities to all 3 sex pheromone components (Ki=0.72-1.60 μM), while SinfPBP2 showed selective binding to the alcohol and aldehyde components (Ki=0.78-1.71 μM), and SinfPBP3 showed no obvious binding to the 3 sex pheromone components. The results suggest that SinfPBP1 plays a major role in the reception of female sex pheromones in S. inferens, while SinfPBP3 plays a least role (if any) and SinfPBP2 functions as a recognizer of alcohol and aldehyde components. Copyright © 2014 Elsevier Ltd. All rights reserved.
10. Pheromone modulates two phenotypically plastic traits - adult reproduction and larval diapause - in the nematode Caenorhabditis elegans.
Science.gov (United States)
Wharam, Barney; Weldon, Laura; Viney, Mark
2017-08-22
Animals use information from their environment to make decisions, ultimately to maximize their fitness. The nematode C. elegans has a pheromone signalling system, which hitherto has principally been thought to be used by worms in deciding whether or not to arrest their development as larvae. Recent studies have suggested that this pheromone can have other roles in the C. elegans life cycle. Here we demonstrate a new role for the C. elegans pheromone, showing that it accelerates hermaphrodites' reproductive rate, a phenomenon which we call pheromone-dependent reproductive plasticity (PDRP). We also find that pheromone accelerates larval growth rates, but this depends on a live bacterial food source, while PDRP does not. Different C. elegans strains all show PDRP, though the magnitude of these effects differ among the strains, which is analogous to the diversity of arrested larval phenotypes that this pheromone also induces. Using a selection experiment we also show that selection for PDRP or for larval arrest affects both the target and the non-target trait, suggesting that there is cross-talk between these two pheromone-dependent traits. Together, these results show that C. elegans' pheromone is a signal that acts at two key life cycle points, controlling alternative larval fates and affecting adult hermaphrodites' reproduction. More broadly, these results suggest that to properly understand and interpret the biology of pheromone signalling in C. elegans and other nematodes, the life-history biology of these organisms in their natural environment needs to be considered.
11. 40 CFR 180.1064 - Tomato pinworm insect pheromone; exemption from the requirement of a tolerance.
Science.gov (United States)
2010-07-01
... 40 Protection of Environment 23 2010-07-01 2010-07-01 false Tomato pinworm insect pheromone... RESIDUES IN FOOD Exemptions From Tolerances § 180.1064 Tomato pinworm insect pheromone; exemption from the... residues of both components of the tomato pinworm insect pheromone (E)-4-tridecen-1-yl acetate and (Z)-4...
12. 40 CFR 180.1080 - Plant volatiles and pheromone; exemptions from the requirement of a tolerance.
Science.gov (United States)
2010-07-01
... 40 Protection of Environment 23 2010-07-01 2010-07-01 false Plant volatiles and pheromone... RESIDUES IN FOOD Exemptions From Tolerances § 180.1080 Plant volatiles and pheromone; exemptions from the... pheromone Z-2-isopropenyl-1-methylcyclobutaneethanol; Z-3,3-dimethyl-Δ1,β-cyclohexaneethanol; Z-3,3-dimethyl...
13. Proteinaceous Pheromone Homologs Identified from the Cloacal Gland Transcriptome of a Male Axolotl, Ambystoma mexicanum.
Directory of Open Access Journals (Sweden)
Kevin W Hall
Full Text Available Pheromones play an important role in modifying vertebrate behavior, especially during courtship and mating. Courtship behavior in urodele amphibians often includes female exposure to secretions from the cloacal gland, as well as other scent glands. The first vertebrate proteinaceous pheromone discovered, the decapeptide sodefrin, is a female attracting pheromone secreted by the cloacal gland of male Cynops pyrrhogaster. Other proteinaceous pheromones in salamanders have been shown to elicit responses from females towards conspecific males. The presence and levels of expression of proteinaceous pheromones have not been identified in the family Ambystomatidae, which includes several important research models. The objective of this research was therefore to identify putative proteinaceous pheromones from male axolotls, Ambystoma mexicanum, as well as their relative expression levels. The results indicate that axolotls possess two different forms of sodefrin precursor-like factor (alpha and beta, as well as a putative ortholog of plethodontid modulating factor. The beta form of sodefrin precursor-like factor was amongst the most highly expressed transcripts within the cloacal gland. The ortholog of plethodontid modulating factor was expressed at a level equivalent to the beta sodefrin precursor-like factor. The results are from a single male axolotl; therefore, we are unable to assess how representative our results may be. Nevertheless, the presence of these highly expressed proteinaceous pheromones suggests that male axolotls use multiple chemical cues to attract female conspecifics. Behavioral assays would indicate whether the putative protein pheromones elicit courtship activity from female axolotls.
14. Proteinaceous Pheromone Homologs Identified from the Cloacal Gland Transcriptome of a Male Axolotl, Ambystoma mexicanum.
Science.gov (United States)
Hall, Kevin W; Eisthen, Heather L; Williams, Barry L
2016-01-01
Pheromones play an important role in modifying vertebrate behavior, especially during courtship and mating. Courtship behavior in urodele amphibians often includes female exposure to secretions from the cloacal gland, as well as other scent glands. The first vertebrate proteinaceous pheromone discovered, the decapeptide sodefrin, is a female attracting pheromone secreted by the cloacal gland of male Cynops pyrrhogaster. Other proteinaceous pheromones in salamanders have been shown to elicit responses from females towards conspecific males. The presence and levels of expression of proteinaceous pheromones have not been identified in the family Ambystomatidae, which includes several important research models. The objective of this research was therefore to identify putative proteinaceous pheromones from male axolotls, Ambystoma mexicanum, as well as their relative expression levels. The results indicate that axolotls possess two different forms of sodefrin precursor-like factor (alpha and beta), as well as a putative ortholog of plethodontid modulating factor. The beta form of sodefrin precursor-like factor was amongst the most highly expressed transcripts within the cloacal gland. The ortholog of plethodontid modulating factor was expressed at a level equivalent to the beta sodefrin precursor-like factor. The results are from a single male axolotl; therefore, we are unable to assess how representative our results may be. Nevertheless, the presence of these highly expressed proteinaceous pheromones suggests that male axolotls use multiple chemical cues to attract female conspecifics. Behavioral assays would indicate whether the putative protein pheromones elicit courtship activity from female axolotls.
15. Factors Affecting sex pheromone production in female cotton leaf worm moth, Spodoptera littoralis (boisd.)
International Nuclear Information System (INIS)
Sallam, H.A.; Hazaa, M.A.; Abd El-Rahman, H.A.; Hussein, M.A.
2000-01-01
Factors influencing sex pheromone production in the cotton leaf worm female moth with emphasis on gamma radiation were investigated. To determine the effect of age on sex pheromone production, ether extracts of the female abdominal tips were prepared from virgin females of various ages in a concentration of 0.01 FE/mu L. Each female extract was tested against 1-2 days-old males. The obtained results indicated that virgin females could secrete sex pheromone early at the beginning of their life. The pheromone production increased rapidly to reach its maximum on the second day. To study the effect of daytime on sex pheromone production, the ether extracts of 1-2 days old virgin female abdominal tips were prepared at 3 hour-intervals, throughout the photo phase and scotophase in a concentration of 0.01 FE/mu L. The obtained results indicated that pheromone production showed a minimum concentration at mid-day during the photo phase. It then increased to a moderate concentration from 7:0 p.m. to 10:0 p.m. and reached its maximum titer at almost mid-night. The obtained data on the effect of gamma irradiation indicated that irradiation of 3 and 6-day-old female pupae with doses of 60 and 120 Gy, respectively caused a reduction of 28.1 and 27.3 % in male response, respectively, to female sex pheromone extracts. When full-grown female pupae were irradiated with 200 and 350 Gy, a reduction of 15.6 and 75% in male response, respectively, was reached. Thus, an irradiation dose of 350 Gy applied to full-grown female pupae could severely affect pheromone production of the emerging female moths
16. Assessment of commercially available pheromone lures for monitoring diamondback moth (Lepidoptera: Plutellidae) in canola.
Science.gov (United States)
Evenden, M L; Gries, R
2010-06-01
Sex pheromone monitoring lures from five different commercial sources were compared for their attractiveness to male diamondback moth, Plutella xylostella L. (Lepidoptera: Plutellidae) in canola, Brassica napus L., fields in western Canada. Lures that had the highest pheromone release rate, as determined by aeration analyses in the laboratory, were the least attractive in field tests. Lures from all the commercial sources tested released more (Z)-11-hexadecenal than (Z)-11-hexadecenyl acetate and the most attractive lures released a significantly higher aldehyde to acetate ratio than less attractive lures. Traps baited with sex pheromone lures from APTIV Inc. (Portland, OR) and ConTech Enterprises Inc. (Delta, BC, Canada) consistently captured more male diamondback moths than traps baited with lures from the other sources tested. In two different lure longevity field trapping experiments, older lures were more attractive to male diamondback moths than fresh lures. Pheromone release from aged lures was constant at very low release rates. The most attractive commercially available sex pheromone lures tested attracted fewer diamondback moth males than calling virgin female moths suggesting that research on the development of a more attractive synthetic sex pheromone lure is warranted.
17. Identification of a sex pheromone of the chrysanthemum lace bug Corythucha marmorata (Hemiptera: Tingidae).
Science.gov (United States)
Watanabe, Kisaki; Shimizu, Nobuhiro
2017-08-04
Although the nymphs of Corythucha marmorata form clusters on the undersides of host plant leaves, as frequently observed for Hemiptera, the adults are scattered in the vicinity of the nymph population. By investigating the biological activities of volatile secretions from the adult, we found that the secretions activated male mounting behaviour. A chemical analysis revealed that borneol was a common component of the secretions from both sexes. The absolute configuration of the natural product was the (+)-enantiomer of borneol and the optical isomer was undetectable. Although (+)-borneol showed significant sex pheromone activity against males, the antipode (-)-borneol also induced sex pheromone activity, albeit only slightly. Males may not have a strict identification mechanism based on stereochemistry. To verify the origin of this sex pheromone, we analysed the components of the essential oil of the leaves of Solidago canadensis L. (Compositae: Asteraceae), a host plant; bornyl acetate was detected to be a major component. The plant-produced bornyl acetate had different stereochemistry from the sex pheromone. The results suggested that the adults do not utilise the secondary metabolites of plants but biosynthesise this sex pheromone themselves. This is the first report on sex pheromone identification in Tingidae.
18. Effect of gamma irradiation on scent gland development and pheromone production in Spodoptera Littoralis
International Nuclear Information System (INIS)
Hazaa, M.A.M.
1995-01-01
The cotton leaf worm, Spodoptera Littoralis (Boisd) is one of the important pests of cotton and many other crops in egypt. Several methods have been tried for its control. Among these, the sterile insect technique and the application of sex attractant pheromones appeared to be promissing in an integrated programme for the control of this and other serious insect pests. The high doses of gamma radiation required in such technique may affect some physiological and biological aspects of the insect as well; specially its reproductive potential. This effect may disturb the intraspecific communication between males and females by adversely affecting pheromone glands and hence pheromone production (Stimman et al., 1972; abdu et al., 1985 and El - Degwi, 1990). Insect sex pheromones are chemical substances secreted by either sex to attract the other sex and get them together for copulation. Trials to seek some of the factors that can prevent such communication in the cotton leaf worm may be of importance in its integrated control programme. This stimulated the present study to investigate the effect of gamma radiation doses on sex pheromone gland and pheromone production in this economically important insect pest.8 tabs., 14 figs., 92 refs
19. REDUCING THE THREAT TO CONTROL INVASIVE SIGNAL CRAYFISH REDUCING: THE POTENTIAL USE OF PHEROMONES
Directory of Open Access Journals (Sweden)
STEBBING P. D.
2003-04-01
Full Text Available The need for an effective method of controlling invasive species of crayfish is of utmost importance given the plight of Europe’s native crayfish species. Many techniques have been applied to the growing problem with little success. Pheromones have been used to control terrestrial insect pests for a number of years with many success stories. The concept of applying pheromone control methods to the aquatic environment is by no means new, but has not been previously developed. This paper discusses the preliminary results from field trials testing traps baited with Pacifastacus leniusculus pheromones, and the potential application of the pheromones in controlling P. leniusculus populations.
20. A Biologically Active Analog of the Sex Pheromone of the Emerald Ash Borer, Agrilus planipennis.
Science.gov (United States)
Silk, P J; Ryall, K; Mayo, P; MaGee, D I; Leclair, G; Fidgen, J; Lavallee, R; Price, J; McConaghy, J
2015-03-01
The emerald ash borer, Agrilus planipennis (Coleoptera: Buprestidae) (EAB), is an invasive species causing unprecedented levels of mortality to ash trees in its introduced range. The female-produced sex pheromone of EAB has been shown to contain the macrocyclic lactone (3Z)-dodecen-12-olide. This compound and its geometrical isomer, (3E)-dodecen-12-olide, have been demonstrated previously to be EAG active and, in combination with a host-derived green leaf volatile, (3Z)-hexenol, to be attractive to male EAB in green prism traps deployed in the ash tree canopy. In the current study, we show that the saturated analog, dodecan-12-olide, is similarly active, eliciting an antennal response and significant attraction of EAB in both olfactometer and trapping bioassays in green traps with (3Z)-hexenol. Conformational modeling of the three lactones reveals that their energies and shapes are very similar, suggesting they might share a common receptor in EAB antennae. These findings provide new insight into the pheromone ecology of this species, highlighting the apparent plasticity in response of adults to the pheromone and its analog. Both of the unsaturated isomers are costly to synthesize, involving multistep, low-yielding processes. The saturated analog can be made cheaply, in high yield, and on large scale via Mitsunobu esterification of a saturated ω-hydroxy acid or more simply by Baeyer-Villiger oxidation of commercially available cyclododecanone. The analog can thus provide an inexpensive option as a lure for detection surveys as well as for possible mitigation purposes, such as mating disruption.
1. Cloning and functional characterization of three new pheromone receptors from the diamondback moth, Plutella xylostella.
Science.gov (United States)
Liu, Yipeng; Liu, Yang; Jiang, Xingchuan; Wang, Guirong
The highly specialized olfactory receptor neurons (ORNs) on the antennae of male moths can recognize blends of several pheromone components. In previous studies, a total of six candidate pheromone receptor (PR) genes were cloned and functionally characterized in the diamondback moth, Plutella xylostella. In the present work, we report on three novel candidate pheromone receptor genes: PxylOR8, PxylOR41, and PxylOR45 in the same species. Gene expression analysis revealed that PxylOR8 is specifically expressed in female adult antennae, while PxylOR41 and PxylOR45 are expressed in antennae in both sexes, but with a male bias. In situ hybridization revealed that PxylOR8, PxylOR41 and PxylOR45 are localized in long trichoid sensilla. Functional analyses on the three pheromone receptor genes were then performed using the heterologous expression system of Xenopus oocytes. PxylOR41 was tuned to two minor pheromone components Z9-14:Ac, Z9-14:OH, and their analog Z9-14:Ald. PxylOR8 and PxylOR45 did not respond to any tested pheromone components and analogs. These results may contribute to clarifying how pheromone detection works in P. xylostella. Copyright © 2018 Elsevier Ltd. All rights reserved.
2. Protein aggregates as depots for the release of biologically active compounds.
Science.gov (United States)
Artemova, Natalya V; Kasakov, Alexei S; Bumagina, Zoya M; Lyutova, Elena M; Gurvits, Bella Ya
2008-12-12
Protein misfolding and aggregation is one of the most serious problems in cell biology, molecular medicine, and biotechnology. Misfolded proteins interact with each other or with other proteins in non-productive or damaging ways. However, a new paradigm arises that protein aggregation may be exploited by nature to perform specific functions in different biological contexts. From this consideration, acceleration of stress-induced protein aggregation triggered by any factor resulting in the formation of soluble aggregates may have paradoxical positive consequences. Here, we suggest that amorphous aggregates can act as a source for the release of biologically active proteins after removal of stress conditions. To address this concept, we investigated the kinetics of thermal aggregation in vitro of yeast alcohol dehydrogenase (ADH) as a model substrate in the presence of two amphiphilic peptides: Arg-Phe or Ala-Phe-Lys. Using dynamic light scattering (DLS) and turbidimetry, we have demonstrated that under mild stress conditions the concentration-dependent acceleration of ADH aggregation by these peptides results in formation of large but soluble complexes of proteins prone to refolding.
3. Male scent-marking pheromone of Bombus ardens ardens (Hymenoptera; Apidae) attracts both conspecific queens and males
Science.gov (United States)
Kubo, Ryohei; Harano, Ken-ichi; Ono, Masato
2017-10-01
To explore the role of the volatiles emitted from male labial gland (LG) of the bumblebee Bombus ardens ardens, we investigated the responses of virgin queens and males to volatiles using a gas chromatography-electroantennographic detector (GC-EAD) system and Y-tube olfactometer. GC-EAD analysis revealed that citronellol, the main compound detected in the male LG, caused clear electrophysiological responses in the antennae of B. a. ardens virgin queens and males although two minor compounds elicited antennal responses when applied in a high concentration. Behavioral tests using a Y-tube olfactometer showed that queens and males were significantly attracted to both LG extracts and citronellol more than to the solvent alone. This is the first study to demonstrate that citronellol as a major compound of male scent-marking pheromone in B. a. ardens functions as a sex attractant for queens. The results also suggest that this compound has another function as a trail marker used by males.
4. Fitness cost of pheromone production in signaling female moths.
Science.gov (United States)
Harari, Ally R; Zahavi, Tirtza; Thiéry, Denis
2011-06-01
A secondary sexual character may act as an honest signal of the quality of the individual if the trait bears a cost and if its expression is phenotypically condition dependent. The cost of increasing the trait should be tolerable for individuals in good condition but not for those in a poor condition. The trait thus provides an honest signal of quality that enables the receiver to choose higher quality mates. Evidence for sex pheromones, which play a major role in shaping sexual evolution, inflicting a signaling cost is scarce. Here, we demonstrate that the amount of the major component of the pheromone in glands of Lobesia botrana (Lepidoptera) females at signaling time was significantly greater in large than in small females, that male moths preferred larger females as mates when responding to volatile signals, and small virgin females, but not large ones, exposed to conspecific pheromone, produced, when mated, significantly fewer eggs than nonexposed females. The latter indicates a condition-dependent cost of signaling. These results are in accordance with the predictions of condition-dependent honest signals. We therefore suggest that female signaling for males using sex pheromones bears a cost and thus calling may serve as honest advertisement for female quality. © 2011 The Author(s). Evolution© 2011 The Society for the Study of Evolution.
5. Synthetic sex pheromone attracts the leishmaniasis vector Lutzomyia longipalpis to experimental chicken sheds treated with insecticide
Directory of Open Access Journals (Sweden)
Brazil Reginaldo P
2010-03-01
Full Text Available Abstract Background Current strategies for controlling American visceral leishmaniasis (AVL have been unable to prevent the spread of the disease across Brazil. With no effective vaccine and culling of infected dogs an unpopular and unsuccessful alternative, new tools are urgently needed to manage populations of the sand fly vector, Lutzomyia longipalpis Lutz and Neiva (Diptera: Psychodidae. Here, we test two potential strategies for improving L. longipalpis control using the synthetic sand fly pheromone (±-9-methylgermacrene-B: the first in conjunction with spraying of animal houses with insecticide, the second using coloured sticky traps. Results Addition of synthetic pheromone resulted in greater numbers of male and female sand flies being caught and killed at experimental chicken sheds sprayed with insecticide, compared to pheromone-less controls. Furthermore, a ten-fold increase in the amount of sex pheromone released from test sheds increased the number of females attracted and subsequently killed. Treating sheds with insecticide alone resulted in a significant decrease in numbers of males attracted to sheds (compared to pre-spraying levels, and a near significant decrease in numbers of females. However, this effect was reversed through addition of synthetic pheromone at the time of insecticide spraying, leading to an increase in number of flies attracted post-treatment. In field trials of commercially available different coloured sticky traps, yellow traps caught more males than blue traps when placed in chicken sheds. In addition, yellow traps fitted with 10 pheromone lures caught significantly more males than pheromone-less controls. However, while female sand flies showed a preference for both blue and yellow pheromone traps sticky traps over white traps in the laboratory, neither colour caught significant numbers of females in chicken sheds, either with or without pheromone. Conclusions We conclude that synthetic pheromone could
6. Structure-Activity Relationship of α Mating Pheromone from the Fungal Pathogen Fusarium oxysporum.
Science.gov (United States)
Vitale, Stefania; Partida-Hanon, Angélica; Serrano, Soraya; Martínez-Del-Pozo, Álvaro; Di Pietro, Antonio; Turrà, David; Bruix, Marta
2017-03-03
During sexual development ascomycete fungi produce two types of peptide pheromones termed a and α. The α pheromone from the budding yeast Saccharomyces cerevisiae , a 13-residue peptide that elicits cell cycle arrest and chemotropic growth, has served as paradigm for the interaction of small peptides with their cognate G protein-coupled receptors. However, no structural information is currently available for α pheromones from filamentous ascomycetes, which are significantly shorter and share almost no sequence similarity with the S. cerevisiae homolog. High resolution structure of synthetic α-pheromone from the plant pathogenic ascomycete Fusarium oxysporum revealed the presence of a central β-turn resembling that of its yeast counterpart. Disruption of the-fold by d-alanine substitution of the conserved central Gly 6 -Gln 7 residues or by random sequence scrambling demonstrated a crucial role for this structural determinant in chemoattractant activity. Unexpectedly, the growth inhibitory effect of F. oxysporum α-pheromone was independent of the cognate G protein-coupled receptors Ste2 and of the central β-turn but instead required two conserved Trp 1 -Cys 2 residues at the N terminus. These results indicate that, despite their reduced size, fungal α-pheromones contain discrete functional regions with a defined secondary structure that regulate diverse biological processes such as polarity reorientation and cell division. © 2017 by The American Society for Biochemistry and Molecular Biology, Inc.
7. Functional characterization of sex pheromone receptors in the purple stem borer, Sesamia inferens (Walker).
Science.gov (United States)
Zhang, Y-N; Zhang, J; Yan, S-W; Chang, H-T; Liu, Y; Wang, G-R; Dong, S-L
2014-10-01
The sex pheromone communication system in moths is highly species-specific and extremely sensitive, and pheromone receptors (PRs) are thought to be the most important factors in males. In the present study, three full-length cDNAs encoding PRs were characterized from Sesamia inferens antennae. These three PRs were all male-specific in expression, but their relative expression levels were very different; SinfOR29 was 17- to 23-fold higher than the other two PRs. Phylogenetic and motif pattern analyses showed that these three PRs were allocated to different PR subfamilies with different motif patterns. Functional analysis using the heterologous expression system of Xenopus oocytes demonstrated that SinfOR29 specifically and sensitively responded to the major pheromone component, Z11-16:OAc [concentration for 50% of maximal effect (EC50 ) = 3.431 × 10(-7) M], while SinfOR21 responded robustly to a minor pheromone component Z11-16:OH (EC50 = 1.087 × 10(-6) M). SinfOR27, however, displayed no response to any of the three pheromone components, but, interestingly, it was sensitive to a non-sex pheromone component Z9,E12-14:OAc (EC50 = 1.522 × 10(-6) M). Our results provide insight into the molecular mechanisms of specificity and sensitivity of the sex pheromone communication system in moths. © 2014 The Royal Entomological Society.
8. 10-Undecenoic Acid, an Inexpensive Source for the Synthesis of the Pheromones of Cotton Pests, Peach Tree Borer and Cherry Tree Borer
Directory of Open Access Journals (Sweden)
1997-06-01
Full Text Available The aldehyde 7, derived from 10-undecenoic acid (5 on cis-selective Wittig reaction with pentylidenetriphenylphosphorane, subsequent deprotection and oxidation gave the pheromone (11Z-hexadecenal (1. Wittig-Horner olefination of 1 with the phosphonate 9 furnished the conjugated ester 10 which on base catalyzed isomerization to the (3Z-ester 11 followed by LAH reduction and acetylation gave (3Z,13Z-octadeadien-1-yl acetate (2. Compound 10 on the other hand was chemoselectively reduced and acetylated to furnish the pheromone (2E,13Z-octadeadien-1-yl acetate (4. For the synthesis of (3E,13Z-octadeadien-1-yl acetate (3, 1 was condensed with malonic acid under modified condition to afford the acid 13 which was converted to 3 by standard reaction protocol.
9. Indium mediated isoprenylation of carbonyl compounds with 2-bromomethyl-1,3-butadiene: a short synthesis of (±-ipsenol
Directory of Open Access Journals (Sweden)
Ceschi Marco A.
2003-01-01
Full Text Available Isoprenylation of aldehydes and ketones was directly performed by selective indium insertion on a mixture of 2-bromomethyl-1,3-butadiene and its vinylic isomers in good yields. A short synthesis of (±-ipsenol, an aggregation pheromone of the Ips paraconfusus bark beetle, demonstrates the utility of this method in organic synthesis.
10. Phylogenetic distribution of a male pheromone that may exploit a nonsexual preference in lampreys.
Science.gov (United States)
Buchinger, T J; Bussy, U; Li, K; Wang, H; Huertas, M; Baker, C F; Jia, L; Hayes, M C; Li, W; Johnson, N S
2017-12-01
Pheromones are among the most important sexual signals used by organisms throughout the animal kingdom. However, few are identified in vertebrates, leaving the evolutionary mechanisms underlying vertebrate pheromones poorly understood. Pre-existing biases in receivers' perceptual systems shape visual and auditory signalling systems, but studies on how receiver biases influence the evolution of pheromone communication remain sparse. The lamprey Petromyzon marinus uses a relatively well-understood suite of pheromones and offers a unique opportunity to study the evolution of vertebrate pheromone communication. Previous studies indicate that male signalling with the mating pheromone 3-keto petromyzonol sulphate (3kPZS) may exploit a nonsexual attraction to juvenile-released 3kPZS that guides migration into productive rearing habitat. Here, we infer the distribution of male signalling with 3kPZS using a phylogenetic comparison comprising six of 10 genera and two of three families. Our results indicate that only P. marinus and Ichthyomyzon castaneus release 3kPZS at high rates. Olfactory and behavioural assays with P. marinus, I. castaneus and a subset of three other species that do not use 3kPZS as a sexual signal indicate that male signalling might have driven the evolution of female adaptations to detect 3kPZS with specific olfactory mechanisms and respond to 3kPZS with targeted attraction relevant during mate search. We postulate that 3kPZS communication evolved independently in I. castaneus and P. marinus, but cannot eliminate the alternative that other species lost 3kPZS communication. Regardless, our results represent a rare macroevolutionary investigation of a vertebrate pheromone and provide insight into the evolutionary mechanisms underlying pheromone communication. © 2017 European Society For Evolutionary Biology. Journal of Evolutionary Biology © 2017 European Society For Evolutionary Biology.
11. Modeling of pheromone communication system of forest Lepidopterous insects. II. Model of female searching by male
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A. V. Kovalev
2015-06-01
Full Text Available We propose an agentbased simulation model search. This model allows us to evaluate the effectiveness of different malesfemales pheromone search strategies for Lepidoptera. In the model, we consider the simplest case of the search, when the pheromone has only one chemical component. It is assumed that the insects are able to detect the pheromone molecules and the sensory cells generate action potentials in contact with the pheromone for some time. Thereafter pheromone molecule is inactivated. This behavior can be regarded as a memory of individual. Proportion of individuals who have reached the source is selected as an integral indicator of the search efficiency. To evaluate the effectiveness, numeric experiments were performed in different conditions: random walk, search algorithm without memory, and algorithm with memory and return mechanism. The resulting effectiveness of source localization by insects for flight in turbulent flows is ~ 70 %, which corresponds to experiments with live specimens in literature. In this case, proposed pheromone search algorithm is quite simple, which makes it biologically correct. Conducted modeling calculations can be the starting point for planning of field observations and pest monitoring systems using pheromone traps.
12. Do aphid colonies amplify their emission of alarm pheromone?
Science.gov (United States)
Hatano, Eduardo; Kunert, Grit; Bartram, Stefan; Boland, Wilhelm; Gershenzon, Jonathan; Weisser, Wolfgang W
2008-09-01
When aphids are attacked by natural enemies, they emit alarm pheromone to alert conspecifics. For most aphids tested, (E)-beta-farnesene (EBF) is the main, or only, constituent of the alarm pheromone. In response to alarm pheromone, alerted aphids drop off the plant, walk away, or attempt to elude predators. However, under natural conditions, EBF concentration might be low due to the low amounts emitted, to rapid air movement, or to oxidative degradation. To ensure that conspecifics are warned, aphids might conceivably amplify the alarm signal by emitting EBF in response to EBF emitted by other aphids. To examine whether such amplification occurs, we synthesized deuterated EBF (DEBF), which allowed us to differentiate between applied and aphid-derived chemical. Colonies of Acyrthosiphon pisum were treated with DEBF, and headspace volatiles were collected and analyzed for evidence of aphid-derived EBF. No aphid-derived EBF was detected, suggesting that amplification of the alarm signal does not occur. We discuss the disadvantages of alarm signal reinforcement.
13. Identification and Isolation of Human Alarm Pheromones
National Research Council Canada - National Science Library
Mujica-Parodi, Lilianne R; Strey, Helmut
2006-01-01
.... Task I, Optimization of Sample Collection, focused on the collection of the putative alarm pheromone via axillary sweat samples obtained during reference (physical exercise) and arousal (skydive) conditions...
14. Spatial focalization of pheromone/MAPK signaling triggers commitment to cell–cell fusion
Science.gov (United States)
Merlini, Laura
2016-01-01
Cell fusion is universal in eukaryotes for fertilization and development, but what signals this process is unknown. Here, we show in Schizosaccharomyces pombe that fusion does not require a dedicated signal but is triggered by spatial focalization of the same pheromone–GPCR (G-protein-coupled receptor)–MAPK signaling cascade that drives earlier mating events. Autocrine cells expressing the receptor for their own pheromone trigger fusion attempts independently of cell–cell contact by concentrating pheromone release at the fusion focus, a dynamic actin aster underlying the secretion of cell wall hydrolases. Pheromone receptor and MAPK cascade are similarly enriched at the fusion focus, concomitant with fusion commitment in wild-type mating pairs. This focalization promotes cell fusion by immobilizing the fusion focus, thus driving local cell wall dissolution. We propose that fusion commitment is imposed by a local increase in MAPK concentration at the fusion focus, driven by a positive feedback between fusion focus formation and focalization of pheromone release and perception. PMID:27798845
15. Kinetic properties of a sex pheromone-degrading enzyme: the sensillar esterase of Antheraea polyphemus.
OpenAIRE
Vogt, R G; Riddiford, L M; Prestwich, G D
1985-01-01
Behavioral and electrophysiological evidence has suggested that sex pheromone is rapidly inactivated within the sensory hairs soon after initiation of the action-potential spike. We report the isolation and characterization of a sex-pheromone-degrading enzyme from the sensory hairs of the silkmoth Antheraea polyphemus. In the presence of this enzyme at physiological concentration, the pheromone [(6E,11Z)-hexadecadienyl acetate] has an estimated half-life of 15 msec. Our findings suggest a mol...
16. A Single Sex Pheromone Receptor Determines Chemical Response Specificity of Sexual Behavior in the Silkmoth Bombyx mori
OpenAIRE
Sakurai, Takeshi; Mitsuno, Hidefumi; Haupt, Stephan Shuichi; Uchino, Keiro; Yokohari, Fumio; Nishioka, Takaaki; Kobayashi, Isao; Sezutsu, Hideki; Tamura, Toshiki; Kanzaki, Ryohei
2011-01-01
In insects and other animals, intraspecific communication between individuals of the opposite sex is mediated in part by chemical signals called sex pheromones. In most moth species, male moths rely heavily on species-specific sex pheromones emitted by female moths to identify and orient towards an appropriate mating partner among a large number of sympatric insect species. The silkmoth, Bombyx mori, utilizes the simplest possible pheromone system, in which a single pheromone component, (E, Z...
17. Stochasticity in the enterococcal sex pheromone response revealed by quantitative analysis of transcription in single cells.
Science.gov (United States)
Breuer, Rebecca J; Bandyopadhyay, Arpan; O'Brien, Sofie A; Barnes, Aaron M T; Hunter, Ryan C; Hu, Wei-Shou; Dunny, Gary M
2017-07-01
In Enterococcus faecalis, sex pheromone-mediated transfer of antibiotic resistance plasmids can occur under unfavorable conditions, for example, when inducing pheromone concentrations are low and inhibiting pheromone concentrations are high. To better understand this paradox, we adapted fluorescence in situ hybridization chain reaction (HCR) methodology for simultaneous quantification of multiple E. faecalis transcripts at the single cell level. We present direct evidence for variability in the minimum period, maximum response level, and duration of response of individual cells to a specific inducing condition. Tracking of induction patterns of single cells temporally using a fluorescent reporter supported HCR findings. It also revealed subpopulations of rapid responders, even under low inducing pheromone concentrations where the overall response of the entire population was slow. The strong, rapid induction of small numbers of cells in cultures exposed to low pheromone concentrations is in agreement with predictions of a stochastic model of the enterococcal pheromone response. The previously documented complex regulatory circuitry controlling the pheromone response likely contributes to stochastic variation in this system. In addition to increasing our basic understanding of the biology of a horizontal gene transfer system regulated by cell-cell signaling, demonstration of the stochastic nature of the pheromone response also impacts any future efforts to develop therapeutic agents targeting the system. Quantitative single cell analysis using HCR also has great potential to elucidate important bacterial regulatory mechanisms not previously amenable to study at the single cell level, and to accelerate the pace of functional genomic studies.
18. A sex pheromone receptor in the Hessian fly Mayetiola destructor (Diptera, Cecidomyiidae
Directory of Open Access Journals (Sweden)
2016-09-01
Full Text Available The Hessian fly, Mayetiola destructor Say (Diptera, Cecidomyiidae, is a pest of wheat and belongs to a group of gall-inducing herbivores. This species has a unique life history and several ecological features that differentiate it from other Diptera such as Drosophila melanogaster and blood-feeding mosquitoes. These features include a short, non-feeding adult life stage (1-2 days and the use of a long-range sex pheromone produced and released by adult females. Sex pheromones are detected by members of the odorant receptor (OR family within the Lepidoptera, but no receptors for similar long-range sex pheromones have been characterized from the Diptera. Previously, 122 OR genes have been annotated from the Hessian fly genome, with many of them showing sex-biased expression in the antennae. Here we have expressed, in HEK293 cells, five MdesORs that display male-biased expression in antennae, and we have identified MdesOR115 as a Hessian fly sex pheromone receptor. MdesOR115 responds primarily to the sex pheromone component (2S,8E,10E-8,10-tridecadien-2-yl acetate, and secondarily to the corresponding Z,E-isomer. Certain sensory neuron membrane proteins (i.e., SNMP1 are important for responses of pheromone receptors in flies and moths. The Hessian fly genome is unusual in that it encodes six SNMP1 paralogues, of which five are expressed in antennae. We co-expressed each of the five antennal SNMP1 paralogues together with each of the five candidate sex pheromone receptors from the Hessian fly and found that they do not influence the response of MdesOR115, nor do they confer responsiveness in any of the non-responsive ORs to any of the sex pheromone components identified to date in the Hessian fly. Using Western blots, we detected protein expression of MdesOrco, all MdesSNMPs, and all MdesORs except for MdesOR113, potentially explaining the lack of response from this OR. In conclusion, we report the first functional characterization of an OR from the
19. Demonstration and Characterization of a Persistent Pheromone Lure for the Navel Orangeworm, Amyelois transitella (Lepidoptera: Pyralidae
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2014-07-01
Full Text Available The lack of an effective pheromone lure has made it difficult to monitor and manage the navel orangeworm, Amyelois transitella (Lepidoptera: Pyralidae, in the economically important crops in which it is the primary insect pest. A series of experiments was conducted to demonstrate and characterize a practical synthetic pheromone lure for capturing navel orangeworm males. Traps baited with lures prepared with 1 or 2 mg of a three- or four-component formulation captured similar numbers of males. The fluctuation over time in the number of males captured in traps baited with the pheromone lure correlated significantly with males captured in female-baited traps. Traps baited with the pheromone lure usually did not capture as many males as traps baited with unmated females, and the ratio of males trapped with pheromone to males trapped with females varied between crops and with abundance. The pheromone lure described improves the ability of pest managers to detect and monitor navel orangeworm efficiently and may improve management and decrease insecticide treatments applied as a precaution against damage. Awareness of differences between male interaction with the pheromone lure and calling females, as shown in these data, will be important as further studies and experience determine how best to use this lure for pest management.
20. Trail communication regulated by two trail pheromone components in the fungus-growing termite Odontotermes formosanus (Shiraki).
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Wen, Ping; Ji, Bao-Zhong; Sillam-Dussès, David
2014-01-01
The eusocial termites are well accomplished in chemical communication, but how they achieve the communication using trace amount of no more than two pheromone components is mostly unknown. In this study, the foraging process and trail pheromones of the fungus-growing termite Odontotermes formosanus (Shiraki) were systematically studied and monitored in real-time using a combination of techniques, including video analysis, solid-phase microextraction, gas chromatography coupled with either mass spectrometry or an electroantennographic detector, and bioassays. The trail pheromone components in foraging workers were (3Z)-dodec-3-en-1-ol and (3Z,6Z)-dodeca-3,6-dien-1-ol secreted by their sternal glands. Interestingly, ratio of the two components changed according to the behaviors that the termites were displaying. This situation only occurs in termites whereas ratios of pheromone components are fixed and species-specific for other insect cuticular glands. Moreover, in bioassays, the active thresholds of the two components ranged from 1 fg/cm to 10 pg/cm according to the behavioral contexts or the pheromonal exposure of tested workers. The two components did not act in synergy. (3Z)-Dodec-3-en-1-ol induced orientation behavior of termites that explore their environment, whereas (3Z,6Z)-dodeca-3,6-dien-1-ol had both an orientation effect and a recruitment effect when food was discovered. The trail pheromone of O. formosanus was regulated both quantitatively by the increasing number of workers involved in the early phases of foraging process, and qualitatively by the change in ratio of the two pheromone components on sternal glandular cuticle in the food-collecting workers. In bioassays, the responses of workers to the pheromone were also affected by the variation in pheromone concentration and component ratio in the microenvironment. Thus, this termite could exchange more information with nestmates using the traces of the two trail pheromone components that can be easily
1. A single sex pheromone receptor determines chemical response specificity of sexual behavior in the silkmoth Bombyx mori.
Science.gov (United States)
Sakurai, Takeshi; Mitsuno, Hidefumi; Haupt, Stephan Shuichi; Uchino, Keiro; Yokohari, Fumio; Nishioka, Takaaki; Kobayashi, Isao; Sezutsu, Hideki; Tamura, Toshiki; Kanzaki, Ryohei
2011-06-01
In insects and other animals, intraspecific communication between individuals of the opposite sex is mediated in part by chemical signals called sex pheromones. In most moth species, male moths rely heavily on species-specific sex pheromones emitted by female moths to identify and orient towards an appropriate mating partner among a large number of sympatric insect species. The silkmoth, Bombyx mori, utilizes the simplest possible pheromone system, in which a single pheromone component, (E, Z)-10,12-hexadecadienol (bombykol), is sufficient to elicit full sexual behavior. We have previously shown that the sex pheromone receptor BmOR1 mediates specific detection of bombykol in the antennae of male silkmoths. However, it is unclear whether the sex pheromone receptor is the minimally sufficient determination factor that triggers initiation of orientation behavior towards a potential mate. Using transgenic silkmoths expressing the sex pheromone receptor PxOR1 of the diamondback moth Plutella xylostella in BmOR1-expressing neurons, we show that the selectivity of the sex pheromone receptor determines the chemical response specificity of sexual behavior in the silkmoth. Bombykol receptor neurons expressing PxOR1 responded to its specific ligand, (Z)-11-hexadecenal (Z11-16:Ald), in a dose-dependent manner. Male moths expressing PxOR1 exhibited typical pheromone orientation behavior and copulation attempts in response to Z11-16:Ald and to females of P. xylostella. Transformation of the bombykol receptor neurons had no effect on their projections in the antennal lobe. These results indicate that activation of bombykol receptor neurons alone is sufficient to trigger full sexual behavior. Thus, a single gene defines behavioral selectivity in sex pheromone communication in the silkmoth. Our findings show that a single molecular determinant can not only function as a modulator of behavior but also as an all-or-nothing initiator of a complex species-specific behavioral sequence.
2. A single sex pheromone receptor determines chemical response specificity of sexual behavior in the silkmoth Bombyx mori.
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Takeshi Sakurai
2011-06-01
Full Text Available In insects and other animals, intraspecific communication between individuals of the opposite sex is mediated in part by chemical signals called sex pheromones. In most moth species, male moths rely heavily on species-specific sex pheromones emitted by female moths to identify and orient towards an appropriate mating partner among a large number of sympatric insect species. The silkmoth, Bombyx mori, utilizes the simplest possible pheromone system, in which a single pheromone component, (E, Z-10,12-hexadecadienol (bombykol, is sufficient to elicit full sexual behavior. We have previously shown that the sex pheromone receptor BmOR1 mediates specific detection of bombykol in the antennae of male silkmoths. However, it is unclear whether the sex pheromone receptor is the minimally sufficient determination factor that triggers initiation of orientation behavior towards a potential mate. Using transgenic silkmoths expressing the sex pheromone receptor PxOR1 of the diamondback moth Plutella xylostella in BmOR1-expressing neurons, we show that the selectivity of the sex pheromone receptor determines the chemical response specificity of sexual behavior in the silkmoth. Bombykol receptor neurons expressing PxOR1 responded to its specific ligand, (Z-11-hexadecenal (Z11-16:Ald, in a dose-dependent manner. Male moths expressing PxOR1 exhibited typical pheromone orientation behavior and copulation attempts in response to Z11-16:Ald and to females of P. xylostella. Transformation of the bombykol receptor neurons had no effect on their projections in the antennal lobe. These results indicate that activation of bombykol receptor neurons alone is sufficient to trigger full sexual behavior. Thus, a single gene defines behavioral selectivity in sex pheromone communication in the silkmoth. Our findings show that a single molecular determinant can not only function as a modulator of behavior but also as an all-or-nothing initiator of a complex species
3. Multiphasic on/off pheromone signalling in moths as neural correlates of a search strategy.
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Dominique Martinez
Full Text Available Insects and robots searching for odour sources in turbulent plumes face the same problem: the random nature of mixing causes fluctuations and intermittency in perception. Pheromone-tracking male moths appear to deal with discontinuous flows of information by surging upwind, upon sensing a pheromone patch, and casting crosswind, upon losing the plume. Using a combination of neurophysiological recordings, computational modelling and experiments with a cyborg, we propose a neuronal mechanism that promotes a behavioural switch between surge and casting. We show how multiphasic On/Off pheromone-sensitive neurons may guide action selection based on signalling presence or loss of the pheromone. A Hodgkin-Huxley-type neuron model with a small-conductance calcium-activated potassium (SK channel reproduces physiological On/Off responses. Using this model as a command neuron and the antennae of tethered moths as pheromone sensors, we demonstrate the efficiency of multiphasic patterning in driving a robotic searcher toward the source. Taken together, our results suggest that multiphasic On/Off responses may mediate olfactory navigation and that SK channels may account for these responses.
4. Multiphasic on/off pheromone signalling in moths as neural correlates of a search strategy.
Science.gov (United States)
Martinez, Dominique; Chaffiol, Antoine; Voges, Nicole; Gu, Yuqiao; Anton, Sylvia; Rospars, Jean-Pierre; Lucas, Philippe
2013-01-01
Insects and robots searching for odour sources in turbulent plumes face the same problem: the random nature of mixing causes fluctuations and intermittency in perception. Pheromone-tracking male moths appear to deal with discontinuous flows of information by surging upwind, upon sensing a pheromone patch, and casting crosswind, upon losing the plume. Using a combination of neurophysiological recordings, computational modelling and experiments with a cyborg, we propose a neuronal mechanism that promotes a behavioural switch between surge and casting. We show how multiphasic On/Off pheromone-sensitive neurons may guide action selection based on signalling presence or loss of the pheromone. A Hodgkin-Huxley-type neuron model with a small-conductance calcium-activated potassium (SK) channel reproduces physiological On/Off responses. Using this model as a command neuron and the antennae of tethered moths as pheromone sensors, we demonstrate the efficiency of multiphasic patterning in driving a robotic searcher toward the source. Taken together, our results suggest that multiphasic On/Off responses may mediate olfactory navigation and that SK channels may account for these responses.
5. Gβ promotes pheromone receptor polarization and yeast chemotropism by inhibiting receptor phosphorylation.
Science.gov (United States)
Ismael, Amber; Tian, Wei; Waszczak, Nicholas; Wang, Xin; Cao, Youfang; Suchkov, Dmitry; Bar, Eli; Metodiev, Metodi V; Liang, Jie; Arkowitz, Robert A; Stone, David E
2016-04-12
Gradient-directed cell migration (chemotaxis) and growth (chemotropism) are processes that are essential to the development and life cycles of all species. Cells use surface receptors to sense the shallow chemical gradients that elicit chemotaxis and chemotropism. Slight asymmetries in receptor activation are amplified by downstream signaling systems, which ultimately induce dynamic reorganization of the cytoskeleton. During the mating response of budding yeast, a model chemotropic system, the pheromone receptors on the plasma membrane polarize to the side of the cell closest to the stimulus. Although receptor polarization occurs before and independently of actin cable-dependent delivery of vesicles to the plasma membrane (directed secretion), it requires receptor internalization. Phosphorylation of pheromone receptors by yeast casein kinase 1 or 2 (Yck1/2) stimulates their internalization. We showed that the pheromone-responsive Gβγ dimer promotes the polarization of the pheromone receptor by interacting with Yck1/2 and locally inhibiting receptor phosphorylation. We also found that receptor phosphorylation is essential for chemotropism, independently of its role in inducing receptor internalization. A mathematical model supports the idea that the interaction between Gβγ and Yck1/2 results in differential phosphorylation and internalization of the pheromone receptor and accounts for its polarization before the initiation of directed secretion. Copyright © 2016, American Association for the Advancement of Science.
6. Temperature dependent rapid annealing effect induces amorphous aggregation of human serum albumin.
Science.gov (United States)
Ishtikhar, Mohd; Ali, Mohd Sajid; Atta, Ayman M; Al-Lohedan, Hammad; Badr, Gamal; Khan, Rizwan Hasan
2016-01-01
This study represents an analysis of the thermal aggregation of human serum albumin (HSA) induced by novel rosin modified compounds. The aggregation process causes conformational alterations in the secondary and tertiary structures of the proteins. The conversion of globular protein to amorphous aggregates was carried out by spectroscopic, calorimetric and microscopic techniques to investigate the factors that are responsible for the structural, conformational and morphological alteration in the protein. Our outcome results show that the aggregation of HSA was dependent on the hydrophobicity, charge and temperature, because the formation of amorphous aggregates occurs in the presence of a novel cationic rosin compound, quaternary amine of rosin diethylaminoethyl ester (QRMAE), at 40°C and pH 7.4 (but at 25°C on similar pH value, there was no evidence of aggregate formation). In addition, the parent compound of QRMAE, i.e., abietic acid, and other derivatives such as nonionic rosin compounds [(RMPEG-750) and (RMA-MPEG-750)] do not shows the aggregating property. This work provides precise and necessary information that aid in the understanding the effects of rosin derivative compounds on HSA. This study also restrains important information for athletes, health providers, pharmaceutical companies, industries, and soft drink-processing companies. Copyright © 2015 Elsevier B.V. All rights reserved.
7. Development of a method to quantitate nematode pheromone for study of small-molecule metabolism in Caenorhabditis elegans.
Science.gov (United States)
Kim, Kwang-Youl; Joo, Hyoe-Jin; Kwon, Hye-Won; Kim, Heekyeong; Hancock, William S; Paik, Young-Ki
2013-03-05
Pheromones produced by Caenorhabditis elegans are considered key regulators of development, mating, and social behaviors in this organism. Here, we present a rapid mass spectrometry-based method (PheroQu) for absolute quantitation of nematode pheromones (e.g., daumone 1, 2, and 3) both in C. elegans worm bodies (as few as 20 worms) and in liquid culture medium. Pheromones were separated by ultra performance liquid chromatography and monitored by a positive electrospray ionization detector in the multiple-reaction monitoring mode. The daf-22 mutant worms were used as surrogate matrix for calibration, and stable deuterated isotope-containing pheromone was used as internal standard for measuring changes in pheromones in N2 wild-type and other strains under different growth conditions. The worm-body pheromones were extracted by acidified acetonitrile solvent, and the secreted pheromones were extracted from culture medium with solid-phase extraction cartridges. The run time was achieved in less than 2 min. The method was validated for specificity, linearity, accuracy, precision, recovery, and stability. The assay was linear over an amount range of 2-250 fmol, and the limit of quantitation was 2 fmol amounts for daumone 1, 2, and 3 in both worm bodies and culture medium. With the PheroQu method, we were able to identify the location of pheromone biosynthesis and determine the changes in different pheromone types synthesized, according to developmental stages and aging process. This method, which is simple, rapid, sensitive, and specific, will be useful for the study of small-molecule metabolism during developmental stages of C. elegans.
8. Primer and short-range releaser pheromone properties of premolt female urine from the shore crab Carcinus maenas.
Science.gov (United States)
Ekerholm, Mattias; Hallberg, Eric
2005-08-01
The European shore crab Carcinus maenas is considered to rely on a female pheromone when mating. Evidence, however, is scarce on how the urine pheromone in itself affects males. We investigated male primer and releaser responses to female pheromones with methods that minimized effects from females, delivering female urine either as a pump-generated plume or deposited on a polyurethane sponge. We delivered the pheromone at different concentrations in far, near, and close/contact range to get a picture of how distance affects behavioral response. Our results show that substances in premolt female urine (PMU) function as primer and potent short-range releaser pheromones. Based on the olfactometer and sponge tests, we conclude that PMU stimulus in itself is sufficient to elicit increased search and mating-specific behaviors such as posing, posing search, cradle carrying, and stroking. Pheromone concentrations do not seem to be important for attenuating search and posing as long as the level is above a certain threshold concentration. Instead, pheromone levels seem to play a role in male acceptance of females, recruiting more males to respond, and generating better responses with increasing concentration.
9. Pheromone-sensing neurons regulate peripheral lipid metabolism in Caenorhabditis elegans.
Science.gov (United States)
Hussey, Rosalind; Stieglitz, Jon; Mesgarzadeh, Jaleh; Locke, Tiffany T; Zhang, Ying K; Schroeder, Frank C; Srinivasan, Supriya
2017-05-01
It is now established that the central nervous system plays an important role in regulating whole body metabolism and energy balance. However, the extent to which sensory systems relay environmental information to modulate metabolic events in peripheral tissues has remained poorly understood. In addition, it has been challenging to map the molecular mechanisms underlying discrete sensory modalities with respect to their role in lipid metabolism. In previous work our lab has identified instructive roles for serotonin signaling as a surrogate for food availability, as well as oxygen sensing, in the control of whole body metabolism. In this study, we now identify a role for a pair of pheromone-sensing neurons in regulating fat metabolism in C. elegans, which has emerged as a tractable and highly informative model to study the neurobiology of metabolism. A genetic screen revealed that GPA-3, a member of the Gα family of G proteins, regulates body fat content in the intestine, the major metabolic organ for C. elegans. Genetic and reconstitution studies revealed that the potent body fat phenotype of gpa-3 null mutants is controlled from a pair of neurons called ADL(L/R). We show that cAMP functions as the second messenger in the ADL neurons, and regulates body fat stores via the neurotransmitter acetylcholine, from downstream neurons. We find that the pheromone ascr#3, which is detected by the ADL neurons, regulates body fat stores in a GPA-3-dependent manner. We define here a third sensory modality, pheromone sensing, as a major regulator of body fat metabolism. The pheromone ascr#3 is an indicator of population density, thus we hypothesize that pheromone sensing provides a salient 'denominator' to evaluate the amount of food available within a population and to accordingly adjust metabolic rate and body fat levels.
10. Communication disruption of guava moth (Coscinoptycha improbana) using a pheromone analog based on chain length.
Science.gov (United States)
Suckling, D M; Dymock, J J; Park, K C; Wakelin, R H; Jamieson, L E
2013-09-01
The guava moth, Coscinoptycha improbana, an Australian species that infests fruit crops in commercial and home orchards, was first detected in New Zealand in 1997. A four-component pheromone blend was identified but is not yet commercially available. Using single sensillum recordings from male antennae, we established that the same olfactory receptor neurons responded to two guava moth sex pheromone components, (Z)-11-octadecen-8-one and (Z)-12-nonadecen-9-one, and to a chain length analog, (Z)-13-eicosen-10-one, the sex pheromone of the related peach fruit moth, Carposina sasakii. We then field tested whether this non-specificity of the olfactory neurons might enable disruption of sexual communication by the commercially available analog, using male catch to synthetic lures in traps in single-tree, nine-tree and 2-ha plots. A disruptive pheromone analog, based on chain length, is reported for the first time. Trap catches for guava moth were disrupted by three polyethylene tubing dispensers releasing the analog in single-tree plots (86% disruption of control catches) and in a plots of nine trees (99% disruption). Where peach fruit moth pheromone dispensers were deployed at a density of 1000/ha in two 2-ha areas, pheromone traps for guava moth were completely disrupted for an extended period (up to 470 days in peri-urban gardens in Mangonui and 422 days in macadamia nut orchards in Kerikeri). In contrast, traps in untreated areas over 100 m away caught 302.8 ± 128.1 moths/trap in Mangonui and 327.5 ± 78.5 moths/ trap in Kerikeri. The longer chain length in the pheromone analog has greater longevity than the natural pheromone due to its lower volatility. Chain length analogs may warrant further investigation for mating disruption in Lepidoptera, and screening using single-sensillum recording is recommended.
11. Range of Attraction of Pheromone Lures and Dispersal Behavior of Cerambycid Beetles
Science.gov (United States)
E. Dunn; J. Hough-Goldstein; L. M. Hanks; J. G. Millar; V. D' Amico
2016-01-01
Cerambycid beetles (Coleoptera: Cerambycidae) can locate suitable hosts and mates by sensing pheromones and plant volatiles. Many cerambycid pheromone components have been identified and are now produced synthetically for trap lures. The range over which these lures attract cerambycids within a forest, and the tendency for cerambycids to move out of a forest in...
12. Pheromones in sex and reproduction: Do they have a role in humans?
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Taymour Mostafa
2012-01-01
Full Text Available Pheromones are found throughout the living world and are a primal form of communication. These chemical messengers are transported outside the body and have a direct developmental effect on hormone levels and/or behaviour. This review article aims to highlight the role of human pheromones in sex and reproduction. A review of published articles was carried out, using PubMed, medical subject heading (MSH databases and the Scopus engine. Key words used to assess exposure, outcome, and estimates for the concerned associations, were; olfaction; sex; pheromones; libido; behaviour; reproduction; humans; and smell. Although there are studies to support this phenomenon, they are weak because they were not controlled; others have proposed that human olfactory communication is able to perceive certain pheromones that may play a role in behavioural as well as reproductive biology. Unfolding the mysteries of smells and the way they are perceived requires more time and effort as humans are not systems that instinctively fall into a behaviour in response to an odour, they are thinking individuals that exercise judgment and subjected to different motivations.
13. Resposta de Cosmopolites sordidus (Germar (Coleoptera, Curculionidae aos voláteis da planta hospedeira e de adultos coespecíficos em olfatômetro Response of Cosmopolites sordidus (Germar (Coleoptera, Curculionidae to host volatiles and conspecific in olfactometer
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Fernando A. C. de Mendonça
1999-01-01
Full Text Available The response of Cosmopolites sordidus (Germar, 1824 to the volatiles of its host banana plant (Musa paradisiaca cv. Prata and conspecific adults was studied. In olfactometer, the attraction of males and females of C. sordidus to rhizome and pseudotem of the banana, fresh or rotting, was observed. The results suggested that the aggregation pheromone is produced by males and that it attracts both sexes, and that there is another pheromone produced by females which attracts males only. The results also suggest that the females are the first responsible for the aggregation of the species, but the male pheromone is mainly responsible for the mass aggregation. Nevertheless, the aggregation phenomenon is a consequence of the mutual action of both pheromones plus the kairomones produced by the banana plant.
14. Investigating a novel pathway by which pheromone-based mating disruption may protect crops
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Pheromone-based mating disruption has been a successful, relatively new technology that growers use to reduce key insect populations. Mating disruption systems function by sending out false plumes of the insect sex pheromones – this interferes with the insect’s ability to find a mate, preempting egg...
15. Role of polarized G protein signaling in tracking pheromone gradients
Science.gov (United States)
McClure, Allison W.; Minakova, Maria; Dyer, Jayme M.; Zyla, Trevin R.; Elston, Timothy C.; Lew, Daniel J.
2015-01-01
Summary Yeast cells track gradients of pheromones to locate mating partners. Intuition suggests that uniform distribution of pheromone receptors over the cell surface would yield optimal gradient sensing. However, yeast cells display polarized receptors. The benefit of such polarization was unknown. During gradient tracking, cell growth is directed by a patch of polarity regulators that wanders around the cortex. Patch movement is sensitive to pheromone dose, with wandering reduced on the up-gradient side of the cell, resulting in net growth in that direction. Mathematical modeling suggests that active receptors and associated G proteins lag behind the polarity patch and act as an effective drag on patch movement. In vivo, the polarity patch is trailed by a G protein-rich domain, and this polarized distribution of G proteins is required to constrain patch wandering. Our findings explain why G protein polarization is beneficial, and illuminate a novel mechanism for gradient tracking. PMID:26609960
16. Mixtures of Two Bile Alcohol Sulfates Function as a Proximity Pheromone in Sea Lamprey.
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Cory O Brant
Full Text Available Unique mixtures of pheromone components are commonly identified in insects, and have been shown to increase attractiveness towards conspecifics when reconstructed at the natural ratio released by the signaler. In previous field studies of pheromones that attract female sea lamprey (Petromyzon marinus, L., putative components of the male-released mating pheromone included the newly described bile alcohol 3,12-diketo-4,6-petromyzonene-24-sulfate (DkPES and the well characterized 3-keto petromyzonol sulfate (3kPZS. Here, we show chemical evidence that unequivocally confirms the elucidated structure of DkPES, electrophysiological evidence that each component is independently detected by the olfactory epithelium, and behavioral evidence that mature female sea lamprey prefer artificial nests activated with a mixture that reconstructs the male-released component ratio of 30:1 (3kPZS:DkPES, molar:molar. In addition, we characterize search behavior (sinuosity of swim paths of females approaching ratio treatment sources. These results suggest unique pheromone ratios may underlie reproductive isolating mechanisms in vertebrates, as well as provide utility in pheromone-integrated control of invasive sea lamprey in the Great Lakes.
17. Cuticular hydrocarbons of Glossina austeni and Glossina pallidipes: Similarities between populations and activity as sex pheromones
International Nuclear Information System (INIS)
Carlson, D.A.; Bernier, U.R.; Sutton, B.D.
2000-01-01
Tsetse flies are a hazard to the health of humans and domestic animals because they spread trypanosomiasis, also known as nagana. Glossina austeni Newstead and Glossina pallidipes Austen are important vectors of this disease in East Africa. Sex pheromones were shown to be present in the surface or cuticular hydrocarbon waterproofing waxes of female of several species of the tsetse fly (Huyton et al. 1980). The pheromones identified in Glossina morsitans morsitans Westwood (Carlson et al. 1978) and G. pallidipes (Carlson et al. 1984, McDowell et al. 1985) have been shown to consist of species-specific, long-chain, high molecular weight hydrocarbons with several methyl branches, present with at least 20 other hydrocarbon compounds in the surface waxes (Nelson and Carlson 1986, Nelson et al. 1988, Sutton and Carlson 1997). The assignment of KI (Kovacx Index) narrows the range of possible methyl-branch configurations in cases of ambiguous or insufficient EI (electron impact) spectra (Carlson et al. 1998). We used gas chromatography/mass spectrometry to demonstrate that different populations of tsetse flies (Carlson et al. 1993) are closely related by investigating these patterns of surface hydrocarbons
18. Re-evaluation of the PBAN receptor molecule: characterization of PBANR variants expressed in the pheromone glands of moths
Science.gov (United States)
Sex pheromone production in most moths is initiated following pheromone biosynthesis activating neuropeptide receptor (PBANR) activation. PBANR was initially cloned from pheromone glands (PGs) of Helicoverpa zea and Bombyx mori. The B. mori PBANR is characterized by a relatively long C-terminus that...
19. A novel mechanism regulating a sexual signal: the testosterone-based inhibition of female sex pheromone expression in garter snakes.
Science.gov (United States)
Parker, M Rockwell; Mason, Robert T
2014-08-01
Vertebrates communicate their sex to conspecifics through the use of sexually dimorphic signals, such as ornaments, behaviors and scents. Furthermore, the physiological connection between hormones and secondary sexual signal expression is key to understanding their dimorphism, seasonality and evolution. The red-sided garter snake (Thamnophis sirtalis parietalis) is the only reptile for which a described pheromone currently exists, and because garter snakes rely completely on the sexual attractiveness pheromone for species identification and mate choice, they constitute a unique model species for exploring the relationship between pheromones and the endocrine system. We recently demonstrated that estrogen can activate female pheromone production in male garter snakes. The purpose of this study was to determine the mechanism(s) acting to prevent female pheromone production in males. We found that castrated males (GX) are courted by wild males in the field and produce appreciable amounts of female sex pheromone. Furthermore, pheromone production is inhibited in castrates given testosterone implants (GX+T), suggesting that pheromone production is actively inhibited by the presence of testosterone. Lastly, testosterone supplementation alone (T) increased the production of several saturated methyl ketones in the pheromone but not the unsaturated ketones; this may indicate that saturated ketones are testosterone-activated components of the garter snake's skin lipid milieu. Collectively, our research has shown that pheromone expression in snakes results from two processes: activation by the feminizing steroid estradiol and inhibition by testosterone. We suggest that basal birds and garter snakes share common pathways of activation that modulate crucial intraspecific signals that originate from skin. Copyright © 2013 Elsevier Inc. All rights reserved.
20. Drosophila pheromone-sensing neurons expressing the ppk25 ion channel subunit stimulate male courtship and female receptivity.
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Vijayan, Vinoy; Thistle, Rob; Liu, Tong; Starostina, Elena; Pikielny, Claudio W
2014-03-01
As in many species, gustatory pheromones regulate the mating behavior of Drosophila. Recently, several ppk genes, encoding ion channel subunits of the DEG/ENaC family, have been implicated in this process, leading to the identification of gustatory neurons that detect specific pheromones. In a subset of taste hairs on the legs of Drosophila, there are two ppk23-expressing, pheromone-sensing neurons with complementary response profiles; one neuron detects female pheromones that stimulate male courtship, the other detects male pheromones that inhibit male-male courtship. In contrast to ppk23, ppk25, is only expressed in a single gustatory neuron per taste hair, and males with impaired ppk25 function court females at reduced rates but do not display abnormal courtship of other males. These findings raised the possibility that ppk25 expression defines a subset of pheromone-sensing neurons. Here we show that ppk25 is expressed and functions in neurons that detect female-specific pheromones and mediates their stimulatory effect on male courtship. Furthermore, the role of ppk25 and ppk25-expressing neurons is not restricted to responses to female-specific pheromones. ppk25 is also required in the same subset of neurons for stimulation of male courtship by young males, males of the Tai2 strain, and by synthetic 7-pentacosene (7-P), a hydrocarbon normally found at low levels in both males and females. Finally, we unexpectedly find that, in females, ppk25 and ppk25-expressing cells regulate receptivity to mating. In the absence of the third antennal segment, which has both olfactory and auditory functions, mutations in ppk25 or silencing of ppk25-expressing neurons block female receptivity to males. Together these results indicate that ppk25 identifies a functionally specialized subset of pheromone-sensing neurons. While ppk25 neurons are required for the responses to multiple pheromones, in both males and females these neurons are specifically involved in stimulating
1. Semiochemicals from herbivory induced cotton plants enhance the foraging behavior of the cotton boll weevil, Anthonomus grandis.
Science.gov (United States)
Magalhães, D M; Borges, M; Laumann, R A; Sujii, E R; Mayon, P; Caulfield, J C; Midega, C A O; Khan, Z R; Pickett, J A; Birkett, M A; Blassioli-Moraes, M C
2012-12-01
The boll weevil, Anthonomus grandis, has been monitored through deployment of traps baited with aggregation pheromone components. However, field studies have shown that the number of insects caught in these traps is significantly reduced during cotton squaring, suggesting that volatiles produced by plants at this phenological stage may be involved in attraction. Here, we evaluated the chemical profile of volatile organic compounds (VOCs) emitted by undamaged or damaged cotton plants at different phenological stages, under different infestation conditions, and determined the attractiveness of these VOCs to adults of A. grandis. In addition, we investigated whether or not VOCs released by cotton plants enhanced the attractiveness of the aggregation pheromone emitted by male boll weevils. Behavioral responses of A. grandis to VOCs from conspecific-damaged, heterospecific-damaged (Spodoptera frugiperda and Euschistus heros) and undamaged cotton plants, at different phenological stages, were assessed in Y-tube olfactometers. The results showed that volatiles emitted from reproductive cotton plants damaged by conspecifics were attractive to adults boll weevils, whereas volatiles induced by heterospecific herbivores were not as attractive. Additionally, addition of boll weevil-induced volatiles from reproductive cotton plants to aggregation pheromone gave increased attraction, relative to the pheromone alone. The VOC profiles of undamaged and mechanically damaged cotton plants, in both phenological stages, were not different. Chemical analysis showed that cotton plants produced qualitatively similar volatile profiles regardless of damage type, but the quantities produced differed according to the plant's phenological stage and the herbivore species. Notably, vegetative cotton plants released higher amounts of VOCs compared to reproductive plants. At both stages, the highest rate of VOC release was observed in A. grandis-damaged plants. Results show that A. grandis uses
2. Nickel aggregates produced by radiolysis
International Nuclear Information System (INIS)
Marignier, J.L.; Belloni, J.
1988-01-01
Nickel aggregates with subcolloidal size and stable in water have been synthesized by inhibiting the corrosion by the medium. The protective effect of the surfactant is discussed in relation with the characteristics of various types of polyvinyl alcohol studied. The reactivity of aggregates towards oxidizing compounds, nitro blue tetrazolium, methylene blue, silver ions, oxygen, methylviologen, enables an estimation of the redox potential of nickel aggregates (E = - 04 ± 0.05 V). It has been applied to quantitative analysis of the particles in presence of nickel ions. 55 refs [fr
3. Factors influencing capture of invasive sea lamprey in traps baited with a synthesized sex pheromone component
Science.gov (United States)
Johnson, Nicholas; Siefkes, Michael J.; Wagner, C. Michael; Bravener, Gale; Steeves, Todd; Twohey, Michael; Li, Weiming
2015-01-01
The sea lamprey, Petromyzon marinus, is emerging as a model organism for understanding how pheromones can be used for manipulating vertebrate behavior in an integrated pest management program. In a previous study, a synthetic sex pheromone component 7α,12α, 24-trihydroxy-5α-cholan-3-one 24-sulfate (3kPZS) was applied to sea lamprey traps in eight streams at a final in-stream concentration of 10−12 M. Application of 3kPZS increased sea lamprey catch, but where and when 3kPZS had the greatest impact was not determined. Here, by applying 3kPZS to additional streams, we determined that overall increases in yearly exploitation rate (proportion of sea lampreys that were marked, released, and subsequently recaptured) were highest (20–40 %) in wide streams (~40 m) with low adult sea lamprey abundance (pheromone), sea lamprey may have been more responsive to a partial sex pheromone blend emitted from traps. Furthermore, we found that the largest and most consistent responses to 3kPZS were during nights early in the trapping season, when water temperatures were increasing. This may have occurred because, during periods of increasing water temperatures, sea lamprey become more active and males at large may not have begun to release sex pheromone. In general, our results are consistent with those for pheromones of invertebrates, which are most effective when pest density is low and when pheromone competition is low.
4. Tissue localization and partial characterization of pheromone ...
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Female sex pheromone production in certain moth species have been shown to be regulated by a cephalic endo- crine peptidic .... A nitrogen laser (659 nm) was used as the desorption/ .... from the Council of Scientific and Industrial Research.
5. Codling Moth, Cydia pomonella (L. (Lep.:Tortricidae Control by Mating Disruption Method by Synthetic Pheromones in Khorasan Razavi Province
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Hashem Kamali
2017-03-01
Full Text Available Introduction: Codling moth, Cydia pomonella is one of the key pests of apple in Khorasan Razavi province which annually causes severe fruit damage to apple crop. There are several ways that are used to control and prevent injury to apple products in the world. The most successful and widespread use of pheromones has been in monitoring traps. Mating disruption method by pheromones takes place when enough artificial sources of pheromone are placed in the area that the chance of finding a female by a male is high. Mating, and laying viable eggs is reduced below the point where economically significant damage occurs. Large-scale mating disruption implementation trials have yielded significant reduction in pesticide use while keeping crop damage levels acceptably low. Mating disruption works best if large areas are treated with the pheromones. Currently, chemical control is the most common method of the pest control by using insecticides. In this research, with the goal of eliminating codling moth and minimizing the use of chemical compounds on the apple fruits, the ability of artificial sex pheromones in controlling the codling moth based on mating disruption method was investigated and compared with chemical control in Ghochan County, Khorasan-e-Razavi Province, Iran, in 2013. Materials and Methods: The experiments were conducted in 20 replicates based on a CRB design. The treatments were mating disruption with pheromone dispensers mating disruption + chemical control and chemical control based on the local method. Adult moth was sampled using Delta traps with a sticky insert. 1000 pheromone, which is a two-strand wire rod was produced has been installed on trees per hectare. Pheromones were installed before the first appearance of male moths. 20 to 25 days after each pest generation, randomly 25 fruits were selected and recorded from different directions and heights base on healthy and infected fruits. Results and Discussion: The mating disruption
6. Sex-linked pheromone receptor genes of the European corn borer, Ostrinia nubilalis, are in tandem arrays.
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Yuji Yasukochi
Full Text Available BACKGROUND: Tuning of the olfactory system of male moths to conspecific female sex pheromones is crucial for correct species recognition; however, little is known about the genetic changes that drive speciation in this system. Moths of the genus Ostrinia are good models to elucidate this question, since significant differences in pheromone blends are observed within and among species. Odorant receptors (ORs play a critical role in recognition of female sex pheromones; eight types of OR genes expressed in male antennae were previously reported in Ostrinia moths. METHODOLOGY/PRINCIPAL FINDINGS: We screened an O. nubilalis bacterial artificial chromosome (BAC library by PCR, and constructed three contigs from isolated clones containing the reported OR genes. Fluorescence in situ hybridization (FISH analysis using these clones as probes demonstrated that the largest contig, which contained eight OR genes, was located on the Z chromosome; two others harboring two and one OR genes were found on two autosomes. Sequence determination of BAC clones revealed the Z-linked OR genes were closely related and tandemly arrayed; moreover, four of them shared 181-bp direct repeats spanning exon 7 and intron 7. CONCLUSIONS/SIGNIFICANCE: This is the first report of tandemly arrayed sex pheromone receptor genes in Lepidoptera. The localization of an OR gene cluster on the Z chromosome agrees with previous findings for a Z-linked locus responsible for O. nubilalis male behavioral response to sex pheromone. The 181-bp direct repeats might enhance gene duplications by unequal crossovers. An autosomal locus responsible for male response to sex pheromone in Heliothis virescens and H. subflexa was recently reported to contain at least four OR genes. Taken together, these findings support the hypothesis that generation of additional copies of OR genes can increase the potential for male moths to acquire altered specificity for pheromone components, and accordingly
7. Larval salivary glands are a source of primer and releaser pheromone in honey bee ( Apis mellifera L.)
Science.gov (United States)
Conte, Yves Le; Bécard, Jean-Marc; Costagliola, Guy; de Vaublanc, Gérard; Maâtaoui, Mohamed El; Crauser, Didier; Plettner, Erika; Slessor, Keith N.
2006-05-01
A brood pheromone identified in honeybee larvae has primer and releaser pheromone effects on adult bees. Using gas chromatography-mass spectrometry (GC-MS) to evaluate fatty acid esters—the pheromonal compounds—in different parts of the larvae, we have localized the source of the esters as the larval salivary glands. A histochemical study describes the glands and confirms the presence of lipids in the glands. Epithelial cells of the gland likely secrete the fatty acids into the lumen of the gland. These results demonstrate the salivary glands to be a reservoir of esters, components of brood pheromone, in honeybee larvae.
8. Alterations in premating behavior and pheromone biology of gamma-irradiated Trichoplusia ni (Lepidoptera:Noctuidae)
International Nuclear Information System (INIS)
Szentesi, A.; McLaughlin, J.R.; Coffelt, J.A.
1977-01-01
Exposure of female cabbage looper pupae, Trichoplusia ni, to gamma irradiation at 0 to 72 hr before eclosion resulted in significantly reduced moving and calling activity of the adults. The effects were dose-related from 10 to 40 kR. Generally, irradiation in a nitrogen atmosphere slightly reduced deleterious effects, but fractionation of the radiation dose did not. Four-day-old irradiated females contained significantly more sex pheromone than untreated females, indicating that loss of pheromone is positively correlated to the amount of calling activity. Males exposed to 20 kR or 40 kR in nitrogen were not affected in their flight response in an olfactometer to a level of synthetic pheromone ca. equal to that released by a calling female or to 0.1 x this level. The response of males exposed to 40 kR in air, however, was significantly decreased at the lower pheromone concentration
9. Re: The Search for Human Pheromones: The Lost Decades and the Necessity of Returning to First Principles
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Fehmi Narter
2017-03-01
Full Text Available EDITORIAL COMMENT Pheromones are chemical signals that have evolved for communication with other members of the same species. We do not know yet if humans have pheromones. Over the last 45 years, some scientists have claimed that a number of molecules are human pheromones, but these claims have little scientific validity. The first chemical identification of a pheromone, the silk moth’s female sex pheromone (bombykol, achieved by the German chemist Adolf Butenandt and after this finding, four steroid molecules have been described as human pheromones: androstenone, androstenol, androstadienone and estratetraenol. The possibility of human pheromones has been downplayed in part because in the past, it has been assumed erroneously that we have a poor sense of smell. Humans have a “main olfactory system” but they do not have a functional vomeronasal organ (or “second nose”; Jacobson’s organ, is an auxiliary olfactory sense organ that is found in many animals. It lies close to the vomer and nasal bones. In the near future, researches will be focused on identification and synthesis of these bioactive molecule(s, followed by bioassay techniques, again. Especially, comparison of secretions from adult and pre-pubertal humans may highlight potential molecules involved in sexual behaviour. Further search will benefit from the techniques developed by olfactory researchers including those who have worked on the steroids previously.
10. Synthesis, crystal structure and aggregation-induced emission of a new pyrene-based compound, 3,3-diphenyl-2-[4-(pyren-1-ylphenyl]acrylonitrile
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Bao-Xi Miao
2018-05-01
Full Text Available The title organic compound, C37H23N, crystallizing in the triclinic space group P\\overline{1}, has been designed, synthesized and characterized by single-crystal X-ray diffaction, MS, NMR and elemental analysis. There are alternating relatively strong and weak intermolecular π–π interactions between adjacent pyrene ring systems, forming a one-dimensional supramolecular structure. The compound is weakly fluorescent in THF solution, but it is highly emissive in the condensed phase, revealing distinct aggregation-induced emission (AIE characteristics.
11. Disruption of Darna pallivitta (Lepidoptera: Limacodidae) by Conventional and Mobile Pheromone Deployment.
Science.gov (United States)
Siderhurst, Matthew S; Jang, Eric B; Carvalho, Lori A F N; Nagata, Janice T; Derstine, Nathan T
2015-01-01
Identification of the Darna pallivitta (Moore) pheromone component n-butyl (E)-7,9-decadienoate (E7,9-10:COOn-Bu) has made it possible to investigate communication disruption to control this lepidopteran pest. Conventional communication disruption trials showed marked decreases in the mean number of male moths captured in E7,9-10:COOnBu-treated fields compared with control fields. For traps baited with E7,9-10:COOnBu, percent disruptions were 94.4% and 92.1% for septa (1 g pheromone/ha, 1-wk trial duration) and spirals (6 g pheromone/ha, 8-wk trial duration) respectively. For traps baited with virgin female moths, percent disruption was 73.3% using septa disruptors (1 g pheromone/ha, 1-wk trial duration). Mobile communication disruption using Bactrocera cucurbitae (Coquillett) as carriers for E7,9-10:COOn-Bu was evaluated in the following three areas: fly survivorship, attraction of male moths to treated flies, and moth disruption in a small-scale field trial. Topical application of E7,9-10:COOnBu showed no significant decrease in survivorship at 50 and 80 µg/fly. However, decreased survivorship was observed at 100 µg/fly and linear regression showed E7,9-10:COOnBu dose was significantly correlated with B. cucurbitae survivorship. Traps containing honey-pheromone-fed flies attracted and caught D. pallivitta over a 1-wk period, demonstrating the attractiveness of the carrier. Releasing E7,9-10:COOnBu-fed B. cucurbitae (∼2 g pheromone/ha, 1-wk trial duration) resulted in significantly reduced trap catches in treatment fields compared with control fields on the first 2 d of the field trial. Percent disruptions were 84.7% (day 1) and 56.0% (day 2). These results suggest that both conventional communication disruption and mobile communication disruption have potential to control D. pallivitta. © The Author 2015. Published by Oxford University Press on behalf of the Entomological Society of America.
12. Effectiveness of Sex Pheromone in Controlling Cocoa Pod Borer, Conopomorpha cramerella (Snell.
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Endang Sulistyowati
2014-08-01
Full Text Available Cocoa pod borer (CPB, Conopomorpha cramerella nell. is a dangerous pest of cocoa which seriously reduce cocoa production mainly in Southeast Asia and Pasific. Prevention of CPB attack can be done by pod sleeving to prevent CPBs lay eggs on pod, or reduction of source of CPB infestation by using pheromone or kairomone as attractant in an insect trap. A preliminary research using sex pheromone has been conducted at endemic cocoa area infested by CPB in East Java. The objective of this study was to evaluate the effectiveness of sex pheromonesin controlling CPB. Trial was arranged by randomized completely block design in four treatments and four blocks as replication. Four densities trap/ha (0, 4, 8, and 12 traps/ha were used as a treatments. Sex pheromone trap consisted of synthetic pheromone (lure and sticky liner was hanged on 0.5 m above the cocoa canopy. The results showed that the number of CPB captured during four months was significantly decreased. The number of CPB captured per trap during the first two months in the treatment of 0, 4, 8 and 12 traps/ha were 0, 6.5, 4.72, and 5.58 CPBs, respectively. Four months after treatment, the number of CPB captured in the respective treatments was reduced to 0, 0.25, 0.6, and 0.96 CPBs. Estimate calculation on yield loss due to CPB attack showed that before treatment the yield loss ranged 37.4—45.6%, however six months after treatment, the yield loss in treatment plots decreased to 9.4—21%, whereas on control 38.47%. Use of sex pheromones to attract CPB at a density of 4 traps/ha reduced yield losses due to CPB damage by 67.7%. The significant correlation betweenthe number of CPB captured with the damage intensity followed regression equation of Y = - 0,00044X + 0,32059. Use of sex pheromone for monitoring or masstrapping of CPB, as a component in IPM of CPB is promising, due to its nature for specific target, environmentally friendly, effectiveness, and economic values
13. Factors Influencing Male Plutella xylostella (Lepidoptera: Plutellidae) Capture Rates in Sex Pheromone-Baited Traps on Canola in Western Canada.
Science.gov (United States)
Miluch, C E; Dosdall, L M; Evenden, M L
2014-12-01
Optimization of male moth trapping rates in sex pheromone-baited traps plays a key role in managing Plutella xylostella (L.). We investigated various ways to increase the attractiveness of pheromone-baited traps to P. xylostella in canola agroecosystems in AB, Canada. Factors tested included pheromone blend and dose, addition of a green leaf volatile to the pheromone at different times during the season, lure type, trap color, and height. The industry standard dose of 100 μg of pheromone (four-component blend) per lure (ConTech Enterprises Inc., Delta, British Columbia [BC], Canada) captured the most moths in the two lure types tested. Traps baited with pheromone released from gray rubber septa captured more males than those baited with red rubber septa. Traps baited with lures in which Z11-16: Ac is the main component attracted significantly more moths than those in which Z11-16: Ald is the main component. The addition of the green leaf volatile, (Z)-3-hexenyl acetate, to pheromone at a range of doses, did not increase moth capture at any point during the canola growing season. Unpainted white traps captured significantly more male moths than pheromone-baited traps that were painted yellow. Trap height had no significant effect on moth capture. Recommendations for monitoring P. xylostella in canola agroecosystems of western Canada include using a pheromone blend with Z11-16: Ac as the main component released from gray rubber septa at a dose of 100 μg. © 2014 Entomological Society of America.
14. Impact of Gamma Radiation on Sex Pheromone Gland of Female and Male Response of Ephestia calidella (Guen.)
International Nuclear Information System (INIS)
Hazaa, M.A.M.; Alm El-Din, M. M. S.; Mikhaiel, A.A.
2012-01-01
The sex pheromone gland of female oases date moth, Ephestia calidella is located inter segmentally between eight and nine abdominal segment. Effect of three sub sterilizing doses 75, 100 and 125 Gy of gamma radiation on pheromone production and on male response were studied. The results obtained revealed that gamma irradiation reduce the pheromone production by female and the responsiveness of male. The effect was increased by increasing the radiation dose. Histological studies of pheromone gland also, indicated that gamma irradiation disturb epithelial cells of the gland and becoming thin at certain parts. Also, gland hairs ruptured or completely disappeared at the highest dose of 125 Gy.
15. Neural correlates underlying naloxone-induced amelioration of sexual behavior deterioration due to an alarm pheromone
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Tatsuya eKobayashi
2015-02-01
Full Text Available Sexual behavior is suppressed by various types of stressors. We previously demonstrated that an alarm pheromone released by stressed male Wistar rats is a stressor to other rats, increases the number of mounts needed for ejaculation, and decreases the hit rate (described as the number of intromissions/sum of the mounts and intromissions. This deterioration in sexual behavior was ameliorated by pretreatment with the opioid receptor antagonist naloxone. However, the neural mechanism underlying this remains to be elucidated. Here, we examined Fos expression in 31 brain regions of pheromone-exposed rats and naloxone-pretreated pheromone-exposed rats 60 min after 10 intromissions. As previously reported, the alarm pheromone increased the number of mounts and decreased the hit rate. In addition, Fos expression was increases in the anterior medial division, anterior lateral division and posterior division of the bed nucleus of the stria terminalis, parvocellular part of the paraventricular nucleus of the hypothalamus, arcuate nucleus, dorsolateral and ventrolateral periaqueductal gray, and nucleus paragigantocellularis. Fos expression decreased in the magnocellular part of the paraventricular nucleus of the hypothalamus. Pretreatment with naloxone blocked the pheromone-induced changes in Fos expression in the magnocellular part of the paraventricular nucleus of the hypothalamus, ventrolateral periaqueductal gray, and nucleus paragigantocellularis. Based on these results, we hypothesize that the alarm pheromone deteriorated sexual behavior by activating the ventrolateral periaqueductal gray-nucleus paragigantocellularis cluster and suppressing the magnocellular part of the paraventricular nucleus of the hypothalamus via the opioidergic pathway.
16. Management strategy evaluation of pheromone-baited trapping techniques to improve management of invasive sea lamprey
Science.gov (United States)
Dawson, Heather; Jones, Michael L.; Irwin, Brian J.; Johnson, Nicholas; Wagner, Michael C.; Szymanski, Melissa
2016-01-01
We applied a management strategy evaluation (MSE) model to examine the potential cost-effectiveness of using pheromone-baited trapping along with conventional lampricide treatment to manage invasive sea lamprey. Four pheromone-baited trapping strategies were modeled: (1) stream activation wherein pheromone was applied to existing traps to achieve 10−12 mol/L in-stream concentration, (2) stream activation plus two additional traps downstream with pheromone applied at 2.5 mg/hr (reverse-intercept approach), (3) trap activation wherein pheromone was applied at 10 mg/hr to existing traps, and (4) trap activation and reverse-intercept approach. Each new strategy was applied, with remaining funds applied to conventional lampricide control. Simulating deployment of these hybrid strategies on fourteen Lake Michigan streams resulted in increases of 17 and 11% (strategies 1 and 2) and decreases of 4 and 7% (strategies 3 and 4) of the lakewide mean abundance of adult sea lamprey relative to status quo. MSE revealed performance targets for trap efficacy to guide additional research because results indicate that combining lampricides and high efficacy trapping technologies can reduce sea lamprey abundance on average without increasing control costs.
17. Flavonoids purified from parsley inhibit human blood platelet aggregation and adhesion to collagen under flow.
Science.gov (United States)
Gadi, Dounia; Bnouham, Mohamed; Aziz, Mohammed; Ziyyat, Abderrahim; Legssyer, Abdelkhaleq; Bruel, Arlette; Berrabah, Mohamed; Legrand, Chantal; Fauvel-Lafeve, Françoise; Mekhfi, Hassane
2012-08-10
Blood platelets are directly involved in both haemostatic and pathologic thrombotic processes, through their adhesion, secretion and aggregation. In this study, we investigated the effect of genins (aglycone flavonoids without sugar group) isolated from parsley (Petroselinum crispum) leaves in vitro on human platelet aggregation and adhesion to a collagen-coated surface under physiologic flow conditions. The aggregation and adhesion studies were monitored after pre-incubation of platelets with genins. Genins inhibited dose dependently aggregation induced by thrombin, ADP and collagen. The strongest effect was observed in collagen induced aggregation (IC50 = 0.08 ± 0.01 mg/ml). The HPLC identification of genins compounds revealed the presence of keampferol, apigenin and other not identified compounds. The aggregation tests showed that these compounds have anti-aggregating activity. In addition, adhesion of human platelets to collagen was greatly decreased (over 75 %) by genins (0.3 mg/ml). While the mechanism by which genins act is unclear, we suggest that these compounds may interfere with a multiple target step in the haemostasis process. These results show that genins isolated from parsley has a potent antiplatelet activity. It may be an important source of beneficial antiplatelet compounds that decrease thrombosis and cardiovascular diseases.
18. Genes involved in sex pheromone biosynthesis of Ephestia cautella, an important food storage pest, are determined by transcriptome sequencing
KAUST Repository
Antony, Binu; Soffan, Alan; Jakše, Jernej; Alfaifi, Sulieman; Sutanto, Koko D.; Aldosari, Saleh A.; Aldawood, Abdulrahman S.; Pain, Arnab
2015-01-01
Our study provides important background information on the enzymes involved in pheromone biosynthesis. This information will be useful for the in vitro production of E. cautella sex pheromones and may provide potential targets for disrupting the pheromone-based communication system of E. cautella to prevent infestations.
19. Identification of lipases involved in PBAN stimulated pheromone production in Bombyx mori using the DGE and RNAi approaches.
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Mengfang Du
Full Text Available BACKGROUND: Pheromone biosynthesis activating neuropeptide (PBAN is a neurohormone that regulates sex pheromone synthesis in female moths. Bombyx mori is a model organism that has been used to explore the signal transduction pattern of PBAN, which is mediated by a G-protein coupled receptor (GPCR. Although significant progress has been made in elucidating PBAN-regulated lipolysis that releases the precursor of the sex pheromone, little is known about the molecular components involved in this step. To better elucidate the molecular mechanisms of PBAN-stimulated lipolysis of cytoplasmic lipid droplets (LDs, the associated lipase genes involved in PBAN- regulated sex pheromone biosynthesis were identified using digital gene expression (DGE and subsequent RNA interference (RNAi. RESULTS: Three DGE libraries were constructed from pheromone glands (PGs at different developed stages, namely, 72 hours before eclosion (-72 h, new emergence (0 h and 72 h after eclosion (72 h, to investigate the gene expression profiles during PG development. The DGE evaluated over 5.6 million clean tags in each PG sample and revealed numerous genes that were differentially expressed at these stages. Most importantly, seven lipases were found to be richly expressed during the key stage of sex pheromone synthesis and release (new emergence. RNAi-mediated knockdown confirmed for the first time that four of these seven lipases play important roles in sex pheromone synthesis. CONCLUSION: This study has identified four lipases directly involved in PBAN-stimulated sex pheromone biosynthesis, which improve our understanding of the lipases involved in releasing bombykol precursors from triacylglycerols (TAGs within the cytoplasmic LDs.
20. LUSH-based SPR sensor for the detection of alcohols and pheromone
Science.gov (United States)
Lau, Hui-Chong; Lee, Yeon-Kyung; Kwon, Jae-Young; Sohn, Young-Soo; Lim, Jeong Ok
2013-05-01
Protein is a widely used sensing substrate in the biosensing technology. In the study conducted here, we used odorant binding protein, LUSH from Drosophila as a biosensing substrate in a miniaturized surface plasmon resonance (SPR) sensor. LUSH contains the specific alcohols binding sites, which mediates the detection of alcohols and pheromone. We first modified the surface of the gold sensor chip using the self assembled monolayer in the chloroform solution. The saturated concentration was determined prior to the detection of alcohols and pheromone at various concentrations. The results showed that the LUSH was saturated at 1000 μg/ml on the gold sensor chip. The detection response of LUSH was significant at higher concentration of alcohols. LUSH detected ethanol at concentration >=50% propanol was detected at >=25% whereas pheromone was detected at >=1.25 μg/μl. The results provide some fundamental information on the potential use of LUSH-based SPR as a simple and easy protein-based sensor in the near future.
1. Functional characterization of an alpha-factor-like Sordaria macrospora peptide pheromone and analysis of its interaction with its cognate receptor in Saccharomyces cerevisiae.
Science.gov (United States)
Mayrhofer, Severine; Pöggeler, Stefanie
2005-04-01
The homothallic filamentous ascomycete Sordaria macrospora possesses genes which are thought to encode two pheromone precursors and two seven-transmembrane pheromone receptors. The pheromone precursor genes are termed ppg1 and ppg2. The putative products derived from the gene sequence show structural similarity to the alpha-factor precursors and a-factor precursors of the yeast Saccharomyces cerevisiae. Likewise, sequence similarity has been found between the putative products of the pheromone receptor genes pre2 and pre1 and the S. cerevisiae Ste2p alpha-factor receptor and Ste3p a-factor receptor, respectively. To investigate whether the alpha-factor-like pheromone-receptor pair of S. macrospora is functional, a heterologous yeast assay was used. Our results show that the S. macrospora alpha-factor-like pheromone precursor PPG1 is processed into an active pheromone by yeast MATalpha cells. The S. macrospora PRE2 protein was demonstrated to be a peptide pheromone receptor. In yeast MATa cells lacking the endogenous Ste2p receptor, the S. macrospora PRE2 receptor facilitated all aspects of the pheromone response. Using a synthetic peptide, we can now predict the sequence of one active form of the S. macrospora peptide pheromone. We proved that S. macrospora wild-type strains secrete an active pheromone into the culture medium and that disruption of the ppg1 gene in S. macrospora prevents pheromone production. However, loss of the ppg1 gene does not affect vegetative growth or fertility. Finally, we established the yeast assay as an easy and useful system for analyzing pheromone production in developmental mutants of S. macrospora.
2. Pheromones enhance somatosensory processing in newt brains through a vasotocin-dependent mechanism.
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Thompson, R R; Dickinson, P S; Rose, J D; Dakin, K A; Civiello, G M; Segerdahl, A; Bartlett, R
2008-07-22
We tested whether the sex pheromones that stimulate courtship clasping in male roughskin newts do so, at least in part, by amplifying the somatosensory signals that directly trigger the motor pattern associated with clasping and, if so, whether that amplification is dependent on endogenous vasotocin (VT). Female olfactory stimuli increased the number of action potentials recorded in the medulla of males in response to tactile stimulation of the cloaca, which triggers the clasp motor reflex, as well as to tactile stimulation of the snout and hindlimb. That enhancement was blocked by exposing the medulla to a V1a receptor antagonist before pheromone exposure. However, the antagonist did not affect medullary responses to tactile stimuli in the absence of pheromone exposure, suggesting that pheromones amplify somatosensory signals by inducing endogenous VT release. The ability of VT to couple sensory systems together in response to social stimulation could allow this peptide to induce variable behavioural outcomes, depending on the immediate context of the social interaction and thus on the nature of the associated stimuli that are amplified. If widespread in vertebrates, this mechanism could account for some of the behavioural variability associated with this and related peptides both within and across species.
3. Aphid alarm pheromone as a cue for ants to locate aphid partners.
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François J Verheggen
Full Text Available The mutualistic relationships that occur between myrmecophilous aphids and ants are based on the rich food supply that honeydew represents for ants and on the protection they provide against aphid natural enemies. While aphid predators and parasitoids actively forage for oviposition sites by using aphid semiochemicals, scouts of aphid-tending ant species would also benefit from locating honeydew resources by orienting toward aphid pheromone sources. The present study aims to provide additional information on the use of Aphis fabae alarm pheromone, i.e. (E-β-farnesene (EβF, by ant scouts. The perception and behavioral impact of EβF on Lasius niger were investigated using electroantennography and two bio-assays measuring their attraction and orientation towards aphid semiochemicals. Pronounced electrical depolarizations were observed from L. niger scout antennae to stimulations of A. fabae alarm pheromone, while other sesquiterpenes elicited weak or no responses. L. niger scouts were significantly attracted toward EβF in a four-arm olfactometer, as well as in an two-choice bioassay. These laboratory results suggest for the first time that low amounts of aphid alarm pheromone can be used by L. niger scouts as a cue indicating the presence of aphid colonies and could therefore mediate the aphid-ant partnership in the field.
4. Differential interactions of sex pheromone and plant odour in the olfactory pathway of a male moth.
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Nina Deisig
Full Text Available Most animals rely on olfaction to find sexual partners, food or a habitat. The olfactory system faces the challenge of extracting meaningful information from a noisy odorous environment. In most moth species, males respond to sex pheromone emitted by females in an environment with abundant plant volatiles. Plant odours could either facilitate the localization of females (females calling on host plants, mask the female pheromone or they could be neutral without any effect on the pheromone. Here we studied how mixtures of a behaviourally-attractive floral odour, heptanal, and the sex pheromone are encoded at different levels of the olfactory pathway in males of the noctuid moth Agrotis ipsilon. In addition, we asked how interactions between the two odorants change as a function of the males' mating status. We investigated mixture detection in both the pheromone-specific and in the general odorant pathway. We used a recordings from individual sensilla to study responses of olfactory receptor neurons, b in vivo calcium imaging with a bath-applied dye to characterize the global input response in the primary olfactory centre, the antennal lobe and c intracellular recordings of antennal lobe output neurons, projection neurons, in virgin and newly-mated males. Our results show that heptanal reduces pheromone sensitivity at the peripheral and central olfactory level independently of the mating status. Contrarily, heptanal-responding olfactory receptor neurons are not influenced by pheromone in a mixture, although some post-mating modulation occurs at the input of the sexually isomorphic ordinary glomeruli, where general odours are processed within the antennal lobe. The results are discussed in the context of mate localization.
5. Effect of pheromone induction on transfer of the Enterococcus faecalis plasmid pCF10 in intestinal mucus ex vivo
DEFF Research Database (Denmark)
Licht, Tine Rask; Hammerum, Anette Marie; Jensen, Lars Bogø
2001-01-01
The effect of synthetic sex pheromone on pheromone-inducible conjugation between the isogenic Enterococcus faecalis strains OG1RF and OG1SS was investigated in (i) Todd-Hewitt broth medium and (ii) intestinal mucus isolated from germ-free rats. In broth, the presence of synthetic pheromone cCF10...
6. Sex pheromone in the moth Heliothis virescens is produced as a mixture of two pools: de novo and via precursor storage in glycerolipids.
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Foster, Stephen P; Anderson, Karin G; Casas, Jérôme
2017-08-01
Most species of moths use a female-produced volatile sex pheromone, typically produced via de novo fatty acid synthesis in a specialized gland, for communication among mates. While de novo biosynthesis of pheromone (DNP) is rapid, suggesting transient precursor acids, substantial amounts of pheromone precursor (and other) acids are stored, predominantly in triacylglycerols in the pheromone gland. Whether these stored acids are converted to pheromone later or not has been the subject of some debate. Using a tracer/tracee approach, in which we fed female Heliothis virescens U- 13 C-glucose, we were able to distinguish two pools of pheromone, in which precursors were temporally separated (after and before feeding on labeled glucose): DNP synthesized from a mixed tracer/tracee acetyl CoA pool after feeding, and pheromone made from precursor acids primarily synthesized before feeding, which we call recycled precursor fat pheromone (RPP). DNP titer varied from high (during scotophase) to low (photophase) and with presence/absence of pheromone biosynthesis activating neuropeptide (PBAN), in accord with native pheromone titer previously observed. By contrast, RPP was constant throughout the photoperiod and did not change with PBAN presence/absence. The amount of RPP (6.3-10.3 ng/female) was typically much lower than that of DNP, especially during the scotophase (peak DNP, 105 ng/female). We propose an integral role for stored fats in pheromone biosynthesis, in which they are hydrolyzed and re-esterified throughout the photoperiod, with a small proportion of liberated precursor acyl CoAs being converted to pheromone. During the sexually active period, release of PBAN results in increased flux of glucose (from trehalose) and hydrolyzed acids entering the mitochondria, producing acetyl CoA precursor for de novo fat and pheromone biosynthesis. Copyright © 2017 Elsevier Ltd. All rights reserved.
7. Biological Control of the Chagas Disease Vector Triatoma infestans with the Entomopathogenic Fungus Beauveria bassiana Combined with an Aggregation Cue: Field, Laboratory and Mathematical Modeling Assessment.
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Lucas Forlani
2015-05-01
Full Text Available Current Chagas disease vector control strategies, based on chemical insecticide spraying, are growingly threatened by the emergence of pyrethroid-resistant Triatoma infestans populations in the Gran Chaco region of South America.We have already shown that the entomopathogenic fungus Beauveria bassiana has the ability to breach the insect cuticle and is effective both against pyrethroid-susceptible and pyrethroid-resistant T. infestans, in laboratory as well as field assays. It is also known that T. infestans cuticle lipids play a major role as contact aggregation pheromones. We estimated the effectiveness of pheromone-based infection boxes containing B. bassiana spores to kill indoor bugs, and its effect on the vector population dynamics. Laboratory assays were performed to estimate the effect of fungal infection on female reproductive parameters. The effect of insect exuviae as an aggregation signal in the performance of the infection boxes was estimated both in the laboratory and in the field. We developed a stage-specific matrix model of T. infestans to describe the fungal infection effects on insect population dynamics, and to analyze the performance of the biopesticide device in vector biological control.The pheromone-containing infective box is a promising new tool against indoor populations of this Chagas disease vector, with the number of boxes per house being the main driver of the reduction of the total domestic bug population. This ecologically safe approach is the first proven alternative to chemical insecticides in the control of T. infestans. The advantageous reduction in vector population by delayed-action fungal biopesticides in a contained environment is here shown supported by mathematical modeling.
8. Ejaculate of sneaker males is pheromonally inconspicuous in the black goby, Gobius niger (Teleostei, Gobiidae).
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Locatello, L; Mazzoldi, C; Rasotto, M B
2002-11-01
The black goby, Gobius niger, shows alternative male mating tactics, i.e., parental and sneaker males. Males release a sexual pheromone that attracts females and stimulates aggressive displays in males. This pheromone is produced by the mesorchial gland, a structure well developed in parental males but markedly undeveloped in sneakers. We measured the behavioral response of parental males to the ejaculates of males performing different reproductive tactics. Parental males reacted to the ejaculate of other parental males, with stereotypic aggressive behaviors, but not to the ejaculate of sneakers; consequently sneaker male ejaculate appears to be pheromonally inconspicuous. Copyright 2002 Wiley-Liss, Inc.
9. Exploring the structural diversity in inhibitors of α-synuclein amyloidogenic folding, aggregation and neurotoxicity
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Das, Sukanya; Pukala, Tara L.; Smid, Scott D.
2018-05-01
Aggregation of α-Synuclein (αS) protein to amyloid fibrils is a neuropathological hallmark of Parkinson’s disease (PD). Growing evidence suggests that extracellular αS aggregation plays a pivotal role in neurodegeneration found in PD in addition to the intracellular αS aggregates in Lewy bodies (LB). Here, we identified and compared a diverse set of molecules capable of mitigating protein aggregation and exogenous toxicity of αSA53T, a more aggregation-prone αS mutant found in familial PD. For the first time, we investigated the αS anti-amyloid activity of semi-synthetic flavonoid 2', 3', 4' trihydroxyflavone or 2-D08, which was compared with natural flavones myricetin and transilitin, as well as such structurally diverse polyphenols as honokiol and punicalagin. Additionally, two novel synthetic compounds with a dibenzyl imidazolidine scaffold, Compound 1 and Compound 2, were also investigated as they exhibited favourable binding with αSA53T. All seven compounds inhibited αSA53T aggregation as demonstrated by Thioflavin T fluorescence assays, with modified fibril morphology observed by transmission electron microscopy. Ion mobility-mass spectrometry (IM-MS) was used to monitor the structural conversion of native αSA53T into amyloidogenic conformations and all seven compounds preserved the native unfolded conformations of αSA53T following 48 hrs incubation. The presence of each test compound in a 1:2 molar ratio was also shown to inhibit the neurotoxicity of preincubated αSA53T using phaeochromocytoma (PC12) cell viability assays. Among the seven tested compounds 2-D08, honokiol and the synthetic Compound 2 demonstrated the highest inhibition of aggregation, coupled with neuroprotection from preincubated αSA53T in vitro. Molecular docking predicted that all compounds bound near the lysine-rich region of the N-terminus of αSA53T, where the flavonoids and honokiol predominantly interacted with Lys 23. Overall, these findings highlight that i
10. Composição química da glândula abdominal da fêmea da mariposa Castnia licus (Drury (Lepidoptera:Castniidae: possíveis feromônios e precursores Chemical composition from female pheromone gland of Castnia licus (Drury (Lepidoptera: Castniidae
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Lúcia M. C. Rebouças
1999-09-01
Full Text Available The hexane and methanolic extracts from pheromonal glands of Castnia licus (Drury virgin females have been studied. Analyses by gas chromatography and mass spectrometry allowed us to determine the major constituents present in the hexane extract as n-alkanes C21 to C30, (Z-9-hexadecenoic acid (C16, and (Z-9-octadecenoic acid (C18 and hexadecanoic acid (C16. Aldehyds, alkenes and acetates were also detected in low concentrations in the extracts. Female pheromone glands were analysed for pheromone precursors using the methanolic extract. In addition to the compounds methyl hexadecanoate and methyl (Z-9-octadecenoate, the glandular tissue contains a homologous series of methyl esters from C12 to C24. The hexane extract of the female abdomenal glands elicited activity from males in a behavioural bioassay.
11. Advances in Attract-and-Kill for Agricultural Pests: Beyond Pheromones.
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Gregg, Peter C; Del Socorro, Alice P; Landolt, Peter J
2018-01-07
Attract-and-kill has considerable potential as a tactic in integrated management of pests of agricultural crops, but the use of sex pheromones as attractants is limited by male multiple mating and immigration of mated females into treated areas. Attractants for both sexes, and particularly females, would minimize these difficulties. Volatile compounds derived from plants or fermentation of plant products can attract females and have been used in traps for monitoring and control, and in sprayable attract-and-kill formulations or bait stations. Recent advances in fundamental understanding of insect responses to plant volatiles should contribute to the development of products that can help manage a wide range of pests with few impacts on nontarget organisms, but theory must be tempered with pragmatism in the selection of volatiles and toxicants and in defining their roles in formulations. Market requirements and regulatory factors must be considered in parallel with scientific constraints if successful products are to be developed.
12. An Insecticide Further Enhances Experience-Dependent Increased Behavioural Responses to Sex Pheromone in a Pest Insect.
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Antoine Abrieux
Full Text Available Neonicotinoid insecticides are widely used to protect plants against pest insects, and insecticide residues remaining in the environment affect both target and non-target organisms. Whereas low doses of neonicotinoids have been shown to disturb the behaviour of pollinating insects, recent studies have revealed that a low dose of the neonicotinoid clothianidin can improve behavioural and neuronal sex pheromone responses in a pest insect, the male moth Agrotis ipsilon, and thus potentially improve reproduction. As male moth behaviour depends also on its physiological state and previous experience with sensory signals, we wondered if insecticide effects would be dependent on plasticity of olfactory-guided behaviour. We investigated, using wind tunnel experiments, whether a brief pre-exposure to the sex pheromone could enhance the behavioural response to this important signal in the moth A. ipsilon at different ages (sexually immature and mature males and after different delays (2 h and 24 h, and if the insecticide clothianidin would interfere with age effects or the potential pre-exposure-effects. Brief pre-exposure to the pheromone induced an age-independent significant increase of sex pheromone responses 24 h later, whereas sex pheromone responses did not increase significantly 2 h after exposure. However, response delays were significantly shorter compared to naïve males already two hours after exposure. Oral treatment with clothianidin increased sex pheromone responses in sexually mature males, confirming previous results, but did not influence responses in young immature males. Males treated with clothianidin after pre-exposure at day 4 responded significantly more to the sex pheromone at day 5 than males treated with clothianidin only and than males pre-exposed only, revealing an additive effect of experience and the insecticide. Plasticity of sensory systems has thus to be taken into account when investigating the effects of sublethal doses
13. An Insecticide Further Enhances Experience-Dependent Increased Behavioural Responses to Sex Pheromone in a Pest Insect.
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Abrieux, Antoine; Mhamdi, Amel; Rabhi, Kaouther K; Egon, Julie; Debernard, Stéphane; Duportets, Line; Tricoire-Leignel, Hélène; Anton, Sylvia; Gadenne, Christophe
2016-01-01
Neonicotinoid insecticides are widely used to protect plants against pest insects, and insecticide residues remaining in the environment affect both target and non-target organisms. Whereas low doses of neonicotinoids have been shown to disturb the behaviour of pollinating insects, recent studies have revealed that a low dose of the neonicotinoid clothianidin can improve behavioural and neuronal sex pheromone responses in a pest insect, the male moth Agrotis ipsilon, and thus potentially improve reproduction. As male moth behaviour depends also on its physiological state and previous experience with sensory signals, we wondered if insecticide effects would be dependent on plasticity of olfactory-guided behaviour. We investigated, using wind tunnel experiments, whether a brief pre-exposure to the sex pheromone could enhance the behavioural response to this important signal in the moth A. ipsilon at different ages (sexually immature and mature males) and after different delays (2 h and 24 h), and if the insecticide clothianidin would interfere with age effects or the potential pre-exposure-effects. Brief pre-exposure to the pheromone induced an age-independent significant increase of sex pheromone responses 24 h later, whereas sex pheromone responses did not increase significantly 2 h after exposure. However, response delays were significantly shorter compared to naïve males already two hours after exposure. Oral treatment with clothianidin increased sex pheromone responses in sexually mature males, confirming previous results, but did not influence responses in young immature males. Males treated with clothianidin after pre-exposure at day 4 responded significantly more to the sex pheromone at day 5 than males treated with clothianidin only and than males pre-exposed only, revealing an additive effect of experience and the insecticide. Plasticity of sensory systems has thus to be taken into account when investigating the effects of sublethal doses of insecticides
14. Of pheromones and kairomones: what receptors mediate innate emotional responses?
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Fortes-Marco, Lluis; Lanuza, Enrique; Martinez-Garcia, Fernando
2013-09-01
Some chemicals elicit innate emotionally laden behavioral responses. Pheromones mediate sexual attraction, parental care or agonistic confrontation, whereas predators' kairomones elicit defensive behaviors in their preys. This essay explores the hypothesis that the detection of these semiochemicals relies on highly specific olfactory and/or vomeronasal receptors. The V1R, V2R, and formyl-peptide vomeronasal receptors bind their ligands in highly specific and sensitive way, thus being good candidates for pheromone- or kairomone-detectors (e.g., secreted and excreted proteins, peptides and lipophilic volatiles). The olfactory epithelium also expresses specific receptors, for example trace amine-associated receptors (TAAR) and guanylyl cyclase receptors (GC-D and other types), some of which bind kairomones and putative pheromones. However, most of the olfactory neurons express canonical olfactory receptors (ORs) that bind many ligands with different affinity, being not suitable for mediating responses to pheromones and kairomones. In this respect, trimethylthiazoline (TMT) is considered a fox-derived kairomone for mice and rats, but it seems to be detected by canonical ORs. Therefore, we have reassessed the kairomonal nature of TMT by analyzing the behavioral responses of outbred (CD1) and inbred mice (C57BL/J6) to TMT. Our results confirm that both mouse strains avoid TMT, which increases immobility in C57BL/J6, but not CD1 mice. However, mice of both strains sniff at TMT throughout the test and show no trace of TMT-induced contextual conditioning (immobility or avoidance). This suggests that TMT is not a kairomone but, similar to a loud noise, in high concentrations it induces aversion and stress as unspecific responses to a strong olfactory stimulation. Copyright © 2013 Wiley Periodicals, Inc.
15. Identification of the Female-Produced Sex Pheromone of an Invasive Greenhouse Pest, the European Pepper Moth (Duponchelia fovealis).
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Molnár, Péter Béla; Bognár, Csengele; Erdei, Anna Laura; Fujii, Takeshi; Vági, Pál; Jósvai, Júlia Katalin; Kárpáti, Zsolt
2018-03-01
The European pepper moth (Duponchelia fovealis, Lepidoptera, Crambidae, Spilomelinae) is an invasive pest of greenhouses in many countries, causing serious damages to horticultural plants. Coupled gas chromatographic-electroantennographic detection analysis of the female gland extract revealed two antennally active peaks. Using coupled gas chromatography-mass spectrometry (GC-MS), one was identified as (Z)-11-hexadecenal (Z11-16:Ald); however, further analysis on different types of capillary columns indicated that the second active compound has two different isomers, (E)-13-octadecenal (E13-18:Ald) and (Z)-13-octadecenal (Z13-18:Ald). The approximate ratio of E13-18:Ald, Z13-18:Ald and Z11-16:Ald in the crude pheromone gland extract was 10:1:0.1, respectively. Single sensillum recordings showed that there was one sensory neuron that responded with a high amplitude spike to both E13-18:Ald and Z13-18:Ald, while another neuron housed in the same sensillum responded to Z11-16:Ald. Field evaluation of the identified compounds indicated that the E13-18:Ald was necessary to evoke the attraction of males; although the presence of Z13-18:Ald and Z11-16:Ald increased the catches in traps. The highest number of caught males was achieved when E13-18:Ald, Z13-18:Ald and Z11-16:Ald were present in baits in the same ratio as in the female gland extract. This pheromone can be used in a monitoring strategy and could potentially lead to the development of mating disruption.
16. Enterococcus faecalis Sex Pheromone cCF10 Enhances Conjugative Plasmid Transfer In Vivo.
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Hirt, Helmut; Greenwood-Quaintance, Kerryl E; Karau, Melissa J; Till, Lisa M; Kashyap, Purna C; Patel, Robin; Dunny, Gary M
2018-02-13
Cell-cell communication mediated by peptide pheromones (cCF10 [CF]) is essential for high-frequency plasmid transfer in vitro in Enterococcus faecalis To examine the role of pheromone signaling in vivo , we established either a CF-producing (CF+) recipient or a recipient producing a biologically inactive variant of CF (CF- recipient) in a germfree mouse model 3 days before donor inoculation and determined transfer frequencies of the pheromone-inducible plasmid pCF10. Plasmid transfer was detected in the upper and middle sections of the intestinal tract 5 h after donor inoculation and was highly efficient in the absence of antibiotic selection. The transconjugant/donor ratio reached a maximum level approaching 1 on day 4 in the upper intestinal tract. Plasmid transfer was significantly lower with the CF- recipient. While rescue of the CF- mating defect by coculture with CF+ recipients is easily accomplished in vitro , no extracellular complementation occurred in vivo This suggests that most pheromone signaling in the gut occurs between recipient and donor cells in very close proximity. Plasmid-bearing cells (donors plus transconjugants) steadily increased in the population from 0.1% after donor inoculation to about 10% at the conclusion of the experiments. This suggests a selective advantage of pCF10 carriage distinct from antibiotic resistance or bacteriocin production. Our results demonstrate that pheromone signaling is required for efficient pCF10 transfer in vivo In the absence of CF+ recipients, a low level of transfer to CF- recipients occurred in the gut. This may result from low-level host-mediated induction of the donors in the gastrointestinal (GI) tract, similar to that previously observed in serum. IMPORTANCE Horizontal gene transfer is a major factor in the biology of Enterococcus faecalis , an important nosocomial pathogen. Previous studies showing efficient conjugative plasmid transfer in the gastrointestinal (GI) tracts of experimental animals did
17. Avoidance and contextual learning induced by a kairomone, a pheromone and a common odorant in female CD1 mice.
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Fortes-Marco, Lluís; Lanuza, Enrique; Martínez-García, Fernando; Agustín-Pavón, Carmen
2015-01-01
Chemosignals mediate both intra- and inter-specific communication in most mammals. Pheromones elicit stereotyped reactions in conspecifics, whereas kairomones provoke a reaction in an allospecific animal. For instance, predator kairomones elicit anticipated defensive responses in preys. The aim of this work was to test the behavioral responses of female mice to two chemosignals: 2-heptanone (2-HP), a putative alarm pheromone, and 2,4,5-trimethylthiazoline (TMT), a fox-derived putative kairomone, widely used to investigate fear and anxiety in rodents. The banana-like odorant isoamyl acetate (IA), unlikely to act as a chemosignal, served as a control odorant. We first presented increasing amounts of these odorants in consecutive days, in a test box in which mice could explore or avoid them. Female mice avoided the highest amounts of all three compounds, with TMT and IA eliciting avoidance at lower amounts (3.8 pmol and 0.35 μmol, respectively) than 2-HP (35 μmol). All three compounds induced minimal effects in global locomotion and immobility in this set up. Further, mice detected 3.5 pmol of TMT and IA in a habituation-dishabituation test, so avoidance of IA started well beyond the detection threshold. Finally, both TMT and IA, but not 2-HP, induced conditioned place avoidance and increased immobility in the neutral compartment during a contextual memory test. These data suggest that intense odors can induce contextual learning irrespective of their putative biological significance. Our results support that synthetic predator-related compounds (like TMT) or other intense odorants are useful to investigate the neurobiological basis of emotional behaviors in rodents. Since intense odorants unlikely to act as chemosignals can elicit similar behavioral reactions than chemosignals, we stress the importance of using behavioral measures in combination with other physiological (e.g., hormonal levels) or neural measures (e.g., immediate early gene expression) to establish
18. Multimodal stimulation of Colorado potato beetle reveals modulation of pheromone response by yellow light.
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Fernando Otálora-Luna
Full Text Available Orientation of insects to host plants and conspecifics is the result of detection and integration of chemical and physical cues present in the environment. Sensory organs have evolved to be sensitive to important signals, providing neural input for higher order multimodal processing and behavioral output. Here we report experiments to determine decisions made by Colorado potato beetle (CPB, Leptinotarsa decemlineata, in response to isolated stimuli and multimodal combinations of signals on a locomotion compensator. Our results show that in complete darkness and in the absence of other stimuli, pheromonal stimulation increases attraction behavior of CPB as measured in oriented displacement and walking speed. However, orientation to the pheromone is abolished when presented with the alternative stimulation of a low intensity yellow light in a dark environment. The ability of the pheromone to stimulate these diurnal beetles in the dark in the absence of other stimuli is an unexpected but interesting observation. The predominance of the phototactic response over that to pheromone when low intensity lights were offered as choices seems to confirm the diurnal nature of the insect. The biological significance of the response to pheromone in the dark is unclear. The phototactic response will play a key role in elucidating multimodal stimulation in the host-finding process of CPB, and perhaps other insects. Such information might be exploited in the design of applications to attract and trap CPB for survey or control purposes and other insect pests using similar orientation mechanisms.
19. Pheromone-assisted techniques to improve the efficacy of insecticide sprays against Linepithema humile (Hymenoptera: Formicidae).
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Choe, Dong-Hwan; Tsai, Kasumi; Lopez, Carlos M; Campbell, Kathleen
2014-02-01
Outdoor residual sprays are among the most common methods for targeting pestiferous ants in urban pest management programs. If impervious surfaces such as concrete are treated with these insecticides, the active ingredients can be washed from the surface by rain or irrigation. As a result, residual sprays with fipronil and pyrethroids are found in urban waterways and aquatic sediments. Given the amount of insecticides applied to urban settings for ant control and their possible impact on urban waterways, the development of alternative strategies is critical to decrease the overall amounts of insecticides applied, while still achieving effective control of target ant species. Herein we report a "pheromone-assisted technique" as an economically viable approach to maximize the efficacy of conventional sprays targeting the Argentine ant. By applying insecticide sprays supplemented with an attractive pheromone compound, (Z)-9-hexadecenal, Argentine ants were diverted from nearby trails and nest entrances and subsequently exposed to insecticide residues. Laboratory experiments with fipronil and bifenthrin sprays indicated that the overall kill of the insecticides on Argentine ant colonies was significantly improved (57-142% increase) by incorporating (Z)-9-hexadecenal in the insecticide sprays. This technique, once it is successfully implemented in practical pest management programs, has the potential of providing maximum control efficacy with reduced amount of insecticides applied in the environment.
20. Diel periodicity of pheromone release by females of Planococcus citri and Planococcus ficus and the temporal flight activity of their conspecific males
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Levi-Zada, Anat; Fefer, Daniela; David, Maayan; Eliyahu, Miriam; Franco, José Carlos; Protasov, Alex; Dunkelblum, Ezra; Mendel, Zvi
2014-08-01
The diel periodicity of sex pheromone release was monitored in two mealybug species, Planococcus citri and Planococcus ficus (Hemiptera; Pseudococcidae), using sequential SPME/GCMS analysis. A maximal release of 2 ng/h pheromone by 9-12-day-old P. citri females occurred 1-2 h before the beginning of photophase. The highest release of pheromone by P. ficus females was 1-2 ng/2 h of 10-20-day-old females, approximately 2 h after the beginning of photophase. Mating resulted in termination of the pheromone release in both mealybug species. The temporal flight activity of the males was monitored in rearing chambers using pheromone baited delta traps. Males of both P. citri and P. ficus displayed the same flight pattern and began flying at 06:00 hours when the light was turned on, reaching a peak during the first and second hour of the photophase. Our results suggest that other biparental mealybug species display also diel periodicities of maximal pheromone release and response. Direct evaluation of the diel periodicity of the pheromone release by the automatic sequential analysis is convenient and will be very helpful in optimizing the airborne collection and identification of other unknown mealybug pheromones and to study the calling behavior of females. Considering this behavior pattern may help to develop more effective pheromone-based management strategies against mealybugs.
1. Structure activity relationship study of curcumin analogues toward the amyloid-beta aggregation inhibitor.
Science.gov (United States)
Endo, Hitoshi; Nikaido, Yuri; Nakadate, Mamiko; Ise, Satomi; Konno, Hiroyuki
2014-12-15
Inhibition of the amyloid β aggregation process could possibly prevent the onset of Alzheimer's disease. In this article, we report a structure-activity relationship study of curcumin analogues for anti amyloid β aggregation activity. Compound 7, the ideal amyloid β aggregation inhibitor in vitro among synthesized curcumin analogues, has not only potent anti amyloid β aggregation effects, but also water solubility more than 160 times that of curcumin. In addition, new approaches to improve water solubility of curcumin-type compounds are proposed. Copyright © 2014 Elsevier Ltd. All rights reserved.
2. Conserved queen pheromones in bumblebees: a reply to Amsalem et al.
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Luke Holman
2017-05-01
Full Text Available In a recent study, Amsalem, Orlova & Grozinger (2015 performed experiments with Bombus impatiens bumblebees to test the hypothesis that saturated cuticular hydrocarbons are evolutionarily conserved signals used to regulate reproductive division of labor in many Hymenopteran social insects. They concluded that the cuticular hydrocarbon pentacosane (C25, previously identified as a queen pheromone in a congeneric bumblebee, does not affect worker reproduction in B. impatiens. Here we discuss some shortcomings of Amsalem et al.’s study that make its conclusions unreliable. In particular, several confounding effects may have affected the results of both experimental manipulations in the study. Additionally, the study’s low sample sizes (mean n per treatment = 13.6, range: 4–23 give it low power, not 96–99% power as claimed, such that its conclusions may be false negatives. Inappropriate statistical tests were also used, and our reanalysis found that C25 substantially reduced and delayed worker egg laying in B. impatiens. We review the evidence that cuticular hydrocarbons act as queen pheromones, and offer some recommendations for future queen pheromone experiments.
3. Behavioural evidence of male volatile pheromones in the sex-role reversed wolf spiders Allocosa brasiliensis and Allocosa alticeps
Science.gov (United States)
Aisenberg, Anita; Baruffaldi, Luciana; González, Macarena
2010-01-01
The use of chemical signals in a sexual context is widespread in the animal kingdom. Most studies in spiders report the use of female pheromones that attract potential sexual partners. Allocosa brasiliensis and Allocosa alticeps are two burrowing wolf spiders that show sex-role reversal. Females locate male burrows and initiate courtship before males perform any detectable visual or vibratory signal. So, females of these species would be detecting chemical or mechanical cues left by males. Our objective was to explore the potential for male pheromones to play a role in mate detection in A. brasiliensis and A. alticeps. We designed two experiments. In Experiment 1, we tested the occurrence of male contact pheromones by evaluating female courtship when exposed to empty burrows constructed by males or females (control). In Experiment 2, we tested the existence of male volatile pheromones by evaluating female behaviour when exposed to artificial burrows connected to tubes containing males, females or empty tubes (control). Our results suggest the occurrence of male volatile pheromones that trigger female courtship in both Allocosa species. The sex-role reversal postulated for these wolf spiders could be driving the consequent reversal in typical pheromone-emitter and detector roles expected for spiders.
4. Enterococcus faecalis Sex Pheromone cCF10 Enhances Conjugative Plasmid Transfer In Vivo
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Helmut Hirt
2018-02-01
Full Text Available Cell-cell communication mediated by peptide pheromones (cCF10 [CF] is essential for high-frequency plasmid transfer in vitro in Enterococcus faecalis. To examine the role of pheromone signaling in vivo, we established either a CF-producing (CF+ recipient or a recipient producing a biologically inactive variant of CF (CF− recipient in a germfree mouse model 3 days before donor inoculation and determined transfer frequencies of the pheromone-inducible plasmid pCF10. Plasmid transfer was detected in the upper and middle sections of the intestinal tract 5 h after donor inoculation and was highly efficient in the absence of antibiotic selection. The transconjugant/donor ratio reached a maximum level approaching 1 on day 4 in the upper intestinal tract. Plasmid transfer was significantly lower with the CF− recipient. While rescue of the CF− mating defect by coculture with CF+ recipients is easily accomplished in vitro, no extracellular complementation occurred in vivo. This suggests that most pheromone signaling in the gut occurs between recipient and donor cells in very close proximity. Plasmid-bearing cells (donors plus transconjugants steadily increased in the population from 0.1% after donor inoculation to about 10% at the conclusion of the experiments. This suggests a selective advantage of pCF10 carriage distinct from antibiotic resistance or bacteriocin production. Our results demonstrate that pheromone signaling is required for efficient pCF10 transfer in vivo. In the absence of CF+ recipients, a low level of transfer to CF− recipients occurred in the gut. This may result from low-level host-mediated induction of the donors in the gastrointestinal (GI tract, similar to that previously observed in serum.
5. Case Study: Trap Crop with Pheromone Traps for Suppressing Euschistus servus (Heteroptera: Pentatomidae in Cotton
Directory of Open Access Journals (Sweden)
P. G. Tillman
2012-01-01
Full Text Available The brown stink bug, Euschistus servus (Say, can disperse from source habitats, including corn, Zea mays L., and peanut, Arachis hypogaea L., into cotton, Gossypium hirsutum L. Therefore, a 2-year on-farm experiment was conducted to determine the effectiveness of a sorghum (Sorghum bicolor (L. Moench spp. bicolor trap crop, with or without Euschistus spp. pheromone traps, to suppress dispersal of this pest to cotton. In 2004, density of E. servus was lower in cotton fields with sorghum trap crops (with or without pheromone traps compared to control cotton fields. Similarly, in 2006, density of E. servus was lower in cotton fields with sorghum trap crops and pheromone traps compared to control cotton fields. Thus, the combination of the sorghum trap crop and pheromone traps effectively suppressed dispersal of E. servus into cotton. Inclusion of pheromone traps with trap crops potentially offers additional benefits, including: (1 reducing the density of E. servus adults in a trap crop, especially females, to possibly decrease the local population over time and reduce the overwintering population, (2 reducing dispersal of E. servus adults from the trap crop into cotton, and (3 potentially attracting more dispersing E. servus adults into a trap crop during a period of time when preferred food is not prevalent in the landscape.
6. Field dispersal ability and taxis to sex pheromone of irradiated F-1 male Asian corn borer
International Nuclear Information System (INIS)
Wang Huasong; Liu Qiongru; Lu Daguang; Wang Endong; Kang Wen; Li Yongjun; He Qiulan; Hu Jianguo
1998-01-01
The dispersal ability of F-1 male Asian corn borer, Ostrinia furnacalis (Guenee), irradiated with 100, 150 and 200 Gy Separately in parental generation were tested by marking (with Calco oil red or Sudan blue internally)-releasing-recapturing (with synthesized sex pheromone) method in the field where the farthest distance from release point to pheromone trap was 550 m. The results showed that, as compared with the normal male moths, despite of the fact that a part of the irradiated F-1 males had lost dispersal ability or taxis to sex pheromone, there was no significant difference between the captured rates of irradiated F-1 males and normal males in the trap 550 m from release point, indicated that the dispersal ability or taxis to sex pheromone of irradiated F-1 males arrived at 550 m from release point are still well matched with the normal ones
7. Aggregation pheromone compounds of the black larder beetle Dermestes haemorrhoidalis Kuster (Coleoptera: Dermestidae)
NARCIS (Netherlands)
2011-01-01
Gas chromatography with simultaneous flame ionisation and electroantennographic detection (GCEAD) and gas chromatography with mass spectrometry analysis (GCMS) of abdominal extracts of adult male Dermestes haemorrhoidalis Kuster (Coleoptera: Dermestidae) revealed the presence of
8. Identification and functional characterization of a sex pheromone receptor in the silkmoth Bombyx mori
Science.gov (United States)
Sakurai, Takeshi; Nakagawa, Takao; Mitsuno, Hidefumi; Mori, Hajime; Endo, Yasuhisa; Tanoue, Shintarou; Yasukochi, Yuji; Touhara, Kazushige; Nishioka, Takaaki
2004-01-01
Sex pheromones released by female moths are detected with high specificity and sensitivity in the olfactory sensilla of antennae of conspecific males. Bombykol in the silkmoth Bombyx mori was the first sex pheromone to be identified. Here we identify a male-specific G protein-coupled olfactory receptor gene, B. mori olfactory receptor 1 (BmOR-1), that appears to encode a bombykol receptor. The BmOR-1 gene is located on the Z sex chromosome, has an eight-exon/seven-intron structure, and exhibits male-specific expression in the pheromone receptor neurons of male moth antenna during late pupal and adult stages. Bombykol stimulation of Xenopus laevis oocytes expressing BmOR-1 and BmGαq elicited robust dose-dependent inward currents on two-electrode voltage clamp recordings, demonstrating that the binding of bombykol to BmOR-1 leads to the activation of a BmGαq-mediated signaling cascade. Antennae of female moths infected with BmOR-1-recombinant baculovirus showed electrophysiological responses to bombykol but not to bombykal. These results provide evidence that BmOR-1 is a G protein-coupled sex pheromone receptor that recognizes bombykol. PMID:15545611
9. Asymmetric total synthesis of a putative sex pheromone component from the parasitoid wasp Trichogramma turkestanica
NARCIS (Netherlands)
Geerdink, Danny; Buter, Jeffrey; van Beek, Teris A.; Minnaard, Adriaan J.
2014-01-01
Virgin females of the parasitoid wasp Trichogramma turkestanica produce minute amounts of a sex pheromone, the identity of which has not been fully established. The enantioselective synthesis of a putative component of this pheromone, (6S,8S,10S)-4,6,8,10-tetramethyltrideca-2E,4E-dien-1-ol (2), is
10. A Drosophila protein family implicated in pheromone perception is related to Tay-Sachs GM2-activator protein.
Science.gov (United States)
Starostina, Elena; Xu, Aiguo; Lin, Heping; Pikielny, Claudio W
2009-01-02
Low volatility, lipid-like cuticular hydrocarbon pheromones produced by Drosophila melanogaster females play an essential role in triggering and modulating mating behavior, but the chemosensory mechanisms involved remain poorly understood. Recently, we showed that the CheB42a protein, which is expressed in only 10 pheromone-sensing taste hairs on the front legs of males, modulates progression to late stages of male courtship behavior in response to female-specific cuticular hydrocarbons. Here we report that expression of all 12 genes in the CheB gene family is predominantly or exclusively gustatory-specific, and occurs in many different, often non-overlapping patterns. Only the Gr family of gustatory receptor genes displays a comparable variety of gustatory-specific expression patterns. Unlike Grs, however, expression of all but one CheB gene is sexually dimorphic. Like CheB42a, other CheBs may therefore function specifically in gustatory perception of pheromones. We also show that CheBs belong to the ML superfamily of lipid-binding proteins, and are most similar to human GM2-activator protein (GM2-AP). In particular, GM2-AP residues involved in ligand binding are conserved in CheBs but not in other ML proteins. Finally, CheB42a is specifically secreted into the inner lumen of pheromone-sensing taste hairs, where pheromones interact with membrane-bound receptors. We propose that CheB proteins interact directly with lipid-like Drosophila pheromones and modulate their detection by the gustatory signal transduction machinery. Furthermore, as loss of GM2-AP in Tay-Sachs disease prevents degradation of GM2 gangliosides and results in neurodegeneration, the function of CheBs in pheromone response may involve biochemical mechanisms critical for lipid metabolism in human neurons.
11. A Drosophila Protein Family Implicated in Pheromone Perception Is Related to Tay-Sachs GM2-Activator Protein*
Science.gov (United States)
Starostina, Elena; Xu, Aiguo; Lin, Heping; Pikielny, Claudio W.
2009-01-01
Low volatility, lipid-like cuticular hydrocarbon pheromones produced by Drosophila melanogaster females play an essential role in triggering and modulating mating behavior, but the chemosensory mechanisms involved remain poorly understood. Recently, we showed that the CheB42a protein, which is expressed in only 10 pheromone-sensing taste hairs on the front legs of males, modulates progression to late stages of male courtship behavior in response to female-specific cuticular hydrocarbons. Here we report that expression of all 12 genes in the CheB gene family is predominantly or exclusively gustatory-specific, and occurs in many different, often non-overlapping patterns. Only the Gr family of gustatory receptor genes displays a comparable variety of gustatory-specific expression patterns. Unlike Grs, however, expression of all but one CheB gene is sexually dimorphic. Like CheB42a, other CheBs may therefore function specifically in gustatory perception of pheromones. We also show that CheBs belong to the ML superfamily of lipid-binding proteins, and are most similar to human GM2-activator protein (GM2-AP). In particular, GM2-AP residues involved in ligand binding are conserved in CheBs but not in other ML proteins. Finally, CheB42a is specifically secreted into the inner lumen of pheromone-sensing taste hairs, where pheromones interact with membrane-bound receptors. We propose that CheB proteins interact directly with lipid-like Drosophila pheromones and modulate their detection by the gustatory signal transduction machinery. Furthermore, as loss of GM2-AP in Tay-Sachs disease prevents degradation of GM2 gangliosides and results in neurodegeneration, the function of CheBs in pheromone response may involve biochemical mechanisms critical for lipid metabolism in human neurons. PMID:18952610
12. Understanding curcumin-induced modulation of protein aggregation.
Science.gov (United States)
Ahmad, Basir; Borana, Mohanish S; Chaudhary, Ankur P
2017-07-01
Curcumin, a diarylheptanoid compound, found in spice turmeric is known to alter the aggregation of proteins and reduce the toxicity of the aggregates. This review looks at the molecular basis of modulating protein aggregation and toxicity of the aggregates. Foremost, we identify the interaction of curcumin and its derivatives with proteins/peptides and the effect of their interaction on the conformational stability and unfolding/folding pathway(s). The unfolding/folding processes generate partially folded/unfolded intermediate, which serve as aggregation precursor state. Secondly, we discuss the effect of curcumin binding on the kinetics parameters of the aggregation process, which give information about the mechanism of the aggregation inhibition. We describe, in addition, that curcumin can accelerate/promote fibril formation by binding to oligomeric intermediate(s) accumulated in the aggregation pathway. Finally, we discuss the correlation of curcumin-induced monomeric and/or oligomeric precursor states with aggregate structure and toxicity. On the basis of these discussions, we propose a model describing curcumin-induced inhibition/promotion of formation of amyloid-like fibrils. Copyright © 2016 Elsevier B.V. All rights reserved.
13. Cross-generational impact of a male murine pheromone 2-sec-butyl-4,5-dihydrothiazole in female mice
Science.gov (United States)
Koyama, Sachiko; Soini, Helena A.; Wager-Miller, James; Alley, William R.; Pizzo, Matthew J.; Rodda, Cathleen; Alberts, Jeffrey; Crystal, Jonathon D.; Lai, Cary; Foley, John; Novotny, Milos V.
2015-01-01
The current understanding of the activity of mammalian pheromones is that endocrine and behavioural effects are limited to the exposed individuals. Here, we demonstrate that the nasal exposure of female mice to a male murine pheromone stimulates expansion of mammary glands, leading to prolonged nursing of pups. Subsequent behavioural testing of the pups from pheromone-exposed dams exhibited enhanced learning. Sialic acid components in the milk are known to be involved in brain development. We hypothesized that the offspring might have received more of this key nutrient that promotes brain development. The mRNA for polysialyltransferase, which produces polysialylated neural cell adhesion molecules related to brain development, was increased in the brain of offspring of pheromone-exposed dams at post-natal day 10, while it was not different at embryonic stages, indicating possible differential brain development during early post-natal life. PMID:26136453
14. Identification of the sex pheromone of Lutzomyia longipalpis (Lutz & Neiva, 1912 (Diptera: Psychodidae from Asunción, Paraguay
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Caballero Norath
2009-11-01
Full Text Available Abstract The sand fly Lutzomyia longipalpis is the main vector of Leishmania (L. infantum (Nicolle, the causative agent of American visceral leishmaniasis (AVL in the New World. Male Lu. longipalpis have secretory glands which produce sex pheromones in either abdominal tergites 4 or 3 and 4. These glands are sites of sex pheromone production and each pheromone type may represent true sibling species. In Latin America, apart from Lu. pseudolongipalpis Arrivillaga and Feliciangeli from Venezuela, populations of Lu. longipalpis s.l. can be identified by their male-produced sex pheromones: (S-9-methylgermacrene-B, 3-methyl-α-himachalene and the two cembrenes, 1 and 2. In this study, we present the results of a coupled gas chromatography - mass spectrometry analysis of the pheromones of males Lu. longipalpis captured in an endemic area of visceral leishmaniasis in Asunción, Paraguay. Our results show that Lu. longipalpis from this site produce (S-9-methylgermacrene-B which has also been found in Lu. longipalpis from different areas of Brazil, Colombia and Central America.
15. Synthesis and field evaluation of synthetic blends of the sex pheromone of Crocidosema aporema (Lepidoptera: Tortricidae) in soybean
Energy Technology Data Exchange (ETDEWEB)
Gonzalez, Andres; Altesor, Paula; Liberati, Paola; Rossini, Carmen [Laboratorio de Ecologia Quimica, Facultad de Quimica, Universidad de la Republica, Montevideo (Uruguay); Alves, Leticia; Ramos, Juan; Carrera, Ignacio; Gonzalez, David; Seoane, Gustavo; Gamenara, Daniela [Departamento de Quimica Organica, Facultad de Quimica, Universidad de la Republica, Montevideo (Uruguay); Silva, Horacio; Castiglioni, Enrique [Departamento de Proteccion Vegetal, Facultad de Agronomia, EEMAC, Universidad de la Republica, Paysandu (Uruguay)
2012-11-15
Crocidosema (= Epinotia) aporema (Walsingham) (Lepidoptera: Tortricidae) is a bud borer that feeds on soybean and forage legumes. Its economic importance is restricted to South America, where it can alternate throughout the year between forage and grain legumes. The sex pheromone of C. aporema females is composed of a 15:1 mixture of (7Z,9Z)-dodeca-7,9-dien-1-ol and (7Z,9Z)- dodeca-7,9-dienyl acetate. Aiming at the development of a monitoring tool, it was synthesized both components of the pheromone and evaluated male captures in pheromone traps baited with different blends of synthetic pheromone, in an experimental soybean field in Uruguay. The conjugated dienes were obtained from 2-pentyn-1-ol and 1,7-heptanediol, by oxidation of the former, Wittig coupling and Zn-catalyzed reduction of the triple bond. The 1:1 mixture was the most efficient in capturing males. The pheromone traps were attractive for up to 40 days, even with small septum loads (0.1 mg) and low population levels. (author)
16. Identification of the sex pheromone of Lutzomyia longipalpis (Lutz & Neiva, 1912) (Diptera: Psychodidae) from Asunción, Paraguay
Science.gov (United States)
Brazil, Reginaldo P; Caballero, Norath Natalia; Hamilton, James Gordon C
2009-01-01
The sand fly Lutzomyia longipalpis is the main vector of Leishmania (L.) infantum (Nicolle), the causative agent of American visceral leishmaniasis (AVL) in the New World. Male Lu. longipalpis have secretory glands which produce sex pheromones in either abdominal tergites 4 or 3 and 4. These glands are sites of sex pheromone production and each pheromone type may represent true sibling species. In Latin America, apart from Lu. pseudolongipalpis Arrivillaga and Feliciangeli from Venezuela, populations of Lu. longipalpis s.l. can be identified by their male-produced sex pheromones: (S)-9-methylgermacrene-B, 3-methyl-α-himachalene and the two cembrenes, 1 and 2. In this study, we present the results of a coupled gas chromatography - mass spectrometry analysis of the pheromones of males Lu. longipalpis captured in an endemic area of visceral leishmaniasis in Asunción, Paraguay. Our results show that Lu. longipalpis from this site produce (S)-9-methylgermacrene-B which has also been found in Lu. longipalpis from different areas of Brazil, Colombia and Central America. PMID:19883505
17. Identification of the sex pheromone of Lutzomyia longipalpis (Lutz & Neiva, 1912) (Diptera: Psychodidae) from Asunción, Paraguay.
Science.gov (United States)
Brazil, Reginaldo P; Caballero, Norath Natalia; Hamilton, James Gordon C
2009-11-02
The sand fly Lutzomyia longipalpis is the main vector of Leishmania (L.) infantum (Nicolle), the causative agent of American visceral leishmaniasis (AVL) in the New World. Male Lu. longipalpis have secretory glands which produce sex pheromones in either abdominal tergites 4 or 3 and 4. These glands are sites of sex pheromone production and each pheromone type may represent true sibling species. In Latin America, apart from Lu. pseudolongipalpis Arrivillaga and Feliciangeli from Venezuela, populations of Lu. longipalpis s.l. can be identified by their male-produced sex pheromones: (S)-9-methylgermacrene-B, 3-methyl-alpha-himachalene and the two cembrenes, 1 and 2.In this study, we present the results of a coupled gas chromatography - mass spectrometry analysis of the pheromones of males Lu. longipalpis captured in an endemic area of visceral leishmaniasis in Asunción, Paraguay. Our results show that Lu. longipalpis from this site produce (S)-9-methylgermacrene-B which has also been found in Lu. longipalpis from different areas of Brazil, Colombia and Central America.
18. Food collection and response to pheromones in an ant species exposed to electromagnetic radiation.
Science.gov (United States)
Cammaerts, Marie-Claire; Rachidi, Zoheir; Bellens, François; De Doncker, Philippe
2013-09-01
We used the ant species Myrmica sabuleti as a model to study the impact of electromagnetic waves on social insects' response to their pheromones and their food collection. We quantified M. sabuleti workers' response to their trail, area marking and alarm pheromone under normal conditions. Then, we quantified the same responses while under the influence of electromagnetic waves. Under such an influence, ants followed trails for only short distances, no longer arrived at marked areas and no longer orientated themselves to a source of alarm pheromone. Also when exposed to electromagnetic waves, ants became unable to return to their nest and recruit congeners; therefore, the number of ants collecting food increases only slightly and slowly. After 180 h of exposure, their colonies deteriorated. Electromagnetic radiation obviously affects social insects' behavior and physiology.
19. Identification of the female-produced sex pheromone of the leafminer Holocacista capensis infesting grapevine in South Africa
NARCIS (Netherlands)
Wang, H.-L.; Geertsema, H.; Nieukerken, van E.J.; Löfstedt, C.
2015-01-01
We report the first identification of a sex pheromone in a heliozelid moth, Holocacista capensis van Nieukerken & Geertsema. This leafminer recently infested grapevine in South Africa. Compared to solvent extraction of pheromone glands, solid phase microextraction (SPME) proved to be highly
20. Geometric isomers of sex pheromone components do not affect attractancy of Conopomorpha cramerella in cocoa plantations
Science.gov (United States)
Sex pheromone of cocoa pod borer (CPB), Conopomorpha cramerella, has previously been identified as a blend of (E,Z,Z)- and (E,E,Z)-4,6,10-hexadecatrienyl acetates and the corresponding alcohols. These pheromone components have been synthesized with modification of the existing method and relative at...
1. Structure elucidation of some insect pheromones : a contribution to the development of selective pest control agents
NARCIS (Netherlands)
Persoons, C.J.
1977-01-01
The use of pheromones is one of the methods currently being investigated intensively as an alternative method of insect control. The various ways in which pheromones might be used in insect control programmes are briefly discussed in Chapter 1.
Chapter 2 gives a detailed description of the
2. Male pheromone protein components activate female vomeronasal neurons in the salamander Plethodon shermani
Directory of Open Access Journals (Sweden)
Feldhoff Pamela W
2006-03-01
Full Text Available Abstract Background The mental gland pheromone of male Plethodon salamanders contains two main protein components: a 22 kDa protein named Plethodon Receptivity Factor (PRF and a 7 kDa protein named Plethodon Modulating Factor (PMF, respectively. Each protein component individually has opposing effects on female courtship behavior, with PRF shortening and PMF lengthening courtship. In this study, we test the hypothesis that PRF or PMF individually activate vomeronasal neurons. The agmatine-uptake technique was used to visualize chemosensory neurons that were activated by each protein component individually. Results Vomeronasal neurons exposed to agmatine in saline did not demonstrate significant labeling. However, a population of vomeronasal neurons was labeled following exposure to either PRF or PMF. When expressed as a percent of control level labeled cells, PRF labeled more neurons than did PMF. These percentages for PRF and PMF, added together, parallel the percentage of labeled vomeronasal neurons when females are exposed to the whole pheromone. Conclusion This study suggests that two specific populations of female vomeronasal neurons are responsible for responding to each of the two components of the male pheromone mixture. These two neural populations, therefore, could express different receptors which, in turn, transmit different information to the brain, thus accounting for the different female behavior elicited by each pheromone component.
3. Female detection of the synthetic sex pheromone contributes to the efficacy of mating disruption of the European grapevine moth, Lobesia botrana.
Science.gov (United States)
Harari, Ally R; Zahavi, Tirtza; Steinitz, Hadass
2015-02-01
Studies of the mechanisms by which mating-disruption techniques control insect pest populations have traditionally focused on the effects of the species-specific sex pheromone on the male moths, while neglecting possible direct effects of the pheromone on females. Here, the effects of exposure to synthetic species-specific sex-pheromone on Lobesia botrana (European grapevine moth) females were tested. Females in vineyards that were treated with mating-disruption pheromone burst into short bouts of flying more frequently, but called significantly less frequently than females in untreated plots. Reduced calling caused by exposure to the species-specific sex-pheromone may increase the age at which females mate and thereby reduce female fecundity. Females that called in a pheromone-saturated environment experienced a decrease in number of oviposited eggs. A further decrease in reproductive success may occur if females delay oviposition when exposed to access of the synthetic pheromone. In addition to reducing the ability of males to locate females, the mating-disruption technique can suppress pest numbers as a consequence of its direct effects on females. The two mechanisms probably act synergistically. © 2014 Society of Chemical Industry.
4. Spatial displacement of release point can enhance activity of an attractant pheromone synergist of a bark beetle.
Science.gov (United States)
Brian Sullivan; Kenji Mori
2009-01-01
Flight responses of the southern pine beetle, Dendroctonus frontalis Zimmermann, to widely-spaced (>130 m) traps baited with pine volatiles (in turpentine) and the female-produced pheromone component frontalin were enhanced when a bait containing the male pheromone component (+)-endo-brevicomin was attached...
5. Pheromone dispensers, including organic polymer fibers, described in the crop protection literature: comparison of their innovation potential.
Science.gov (United States)
Hummel, Hans E; Langner, S S; Eisinger, M-T
2013-01-01
Pheromone dispensers, although known in a variety of different designs, are one of the few remaining technical bottlenecks along the way to a sustainable pheromone based strategy in integrated pest management (IPM). Mating disruption with synthetic pheromones is a viable pest management approach. Suitable pheromone dispensers for these mating disruption schemes, however, are lagging behind the general availability of pheromones. Specifically, there is a need for matching the properties of the synthetic pheromones, the release rates suitable for certain insect species, and the environmental requirements of specific crop management. The "ideal" dispenser should release pheromones at a constant but pre-adjustable rate, should be mechanically applicable, completely biodegradable and thus save the costs for recovering spent dispensers. These should be made from renewable, cheap organic material, be economically inexpensive, and be toxicologically and eco-toxicologically inert to provide satisfactory solutions for the needs of practicing growers. In favourable cases, they will be economically competitive with conventional pesticide treatments and by far superior in terms of environmental and eco-toxicological suitability. In the course of the last 40 years, mating disruption, a non-toxicological approach, provided proof for its potential in dozens of pest insects of various orders and families. Applications for IPM in many countries of the industrialized and developing world have been reported. While some dispensers have reached wide circulation, only few of the key performing parameters fit the above requirements ideally and must be approximated with some sacrifice in performance. A fair comparison of the innovation potential of currently available pheromone dispensers is attempted. The authors advance here the use of innovative electrospun organic fibers with dimensions in the "meso" (high nano- to low micrometer) region. Due to their unique multitude of adjustable
6. Trail marking and following by larvae of the small ermine moth Yponomeuta cagnagellus
NARCIS (Netherlands)
Roessingh, P.
1989-01-01
The importance of chemical cues in insect behaviour is well established (Bell & Cardé, 1984). The best known examples include the sex pheromones of butterflies and moths, and the aggregation pheromones of bark beetles. In eusocial insects (bees, wasps, ants, and termites) pheromones are
7. Thermodynamics of the hydrophobic effect. III. Condensation and aggregation of alkanes, alcohols, and alkylamines.
Science.gov (United States)
Matulis, D
2001-10-18
Knowledge of the energetics of the low solubility of non-polar compounds in water is critical for the understanding of such phenomena as protein folding and biomembrane formation. Solubility in water can be considered as one leg of the three-part thermodynamic cycle - vaporization from the pure liquid, hydration of the vapor in aqueous solution, and aggregation of the substance back into initial pure form as an immiscible phase. Previous studies on the model compounds n-alkanes, 1-alcohols, and 1-aminoalkanes have noted that the thermodynamic parameters (Gibbs free energy, DeltaG; enthalpy, DeltaH; entropy, DeltaS; and heat capacity, DeltaC(p)) associated with these three processes are generally linear functions of the number of carbons in the alkyl chains. Here we assess the accuracy and limitations of the assumption of additivity of CH(2) group contributions to the thermodynamic parameters for vaporization, hydration, and aggregation. Processes of condensation from pure gas to liquid and aqueous solution to aggregate are compared. Hydroxy, amino, and methyl headgroup contributions are estimated, liquid and solid aggregates are distinguished. Most data in the literature were obtained for compounds with short aliphatic hydrocarbon tails. Here we emphasize long aliphatic chain behavior and include our recent experimental data on long chain alkylamine aggregation in aqueous solution obtained by titration calorimetry and van't Hoff analysis. Contrary to what is observed for short compounds, long aliphatic compound aggregation has a large exothermic enthalpy and negative entropy.
8. A reference gene set for sex pheromone biosynthesis and degradation genes from the diamondback moth, Plutella xylostella, based on genome and transcriptome digital gene expression analyses
OpenAIRE
He, Peng; Zhang, Yun-Fei; Hong, Duan-Yang; Wang, Jun; Wang, Xing-Liang; Zuo, Ling-Hua; Tang, Xian-Fu; Xu, Wei-Ming; He, Ming
2017-01-01
Background Female moths synthesize species-specific sex pheromone components and release them to attract male moths, which depend on precise sex pheromone chemosensory system to locate females. Two types of genes involved in the sex pheromone biosynthesis and degradation pathways play essential roles in this important moth behavior. To understand the function of genes in the sex pheromone pathway, this study investigated the genome-wide and digital gene expression of sex pheromone biosynthesi...
9. Resisting majesty: Apis cerana, has lower antennal sensitivity and decreased attraction to queen mandibular pheromone than Apis mellifera
Science.gov (United States)
Dong, Shihao; Wen, Ping; Zhang, Qi; Li, Xinyu; Tan, Ken; Nieh, James
2017-03-01
In highly social bees, queen mandibular pheromone (QMP) is vital for colony life. Both Apis cerana (Ac) and Apis mellifera (Am) share an evolutionarily conserved set of QMP compounds: (E)-9-oxodec-2-enoic acid (9-ODA), (E)-9-hydroxydec-2-enoic acid (9-HDA), (E)-10-hydroxy-dec-2-enoic acid (10-HDA), 10-hydroxy-decanoic acid (10-HDAA), and methyl p-hydroxybenzoate (HOB) found at similar levels. However, evidence suggests there may be species-specific sensitivity differences to QMP compounds because Ac workers have higher levels of ovarian activation than Am workers. Using electroantennograms, we found species-specific sensitivity differences for a blend of the major QMP compounds and three individual compounds (9-HDA, 10-HDAA, and 10-HDA). As predicted, Am was more sensitive than Ac in all cases (1.3- to 2.7- fold higher responses). There were also species differences in worker retinue attraction to three compounds (9-HDA, HOB, and 10-HDA). In all significantly different cases, Am workers were 4.5- to 6.2-fold more strongly attracted than Ac workers were. Thus, Ac workers responded less strongly to QMP than Ac workers, and 9-HDA and 10-HDA consistently elicited stronger antennal and retinue formation responses.
10. Benzbromarone, Quercetin, and Folic Acid Inhibit Amylin Aggregation
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Laura C. López
2016-06-01
Full Text Available Human Amylin, or islet amyloid polypeptide (hIAPP, is a small hormone secreted by pancreatic β-cells that forms aggregates under insulin deficiency metabolic conditions, and it constitutes a pathological hallmark of type II diabetes mellitus. In type II diabetes patients, amylin is abnormally increased, self-assembled into amyloid aggregates, and ultimately contributes to the apoptotic death of β-cells by mechanisms that are not completely understood. We have screened a library of approved drugs in order to identify inhibitors of amylin aggregation that could be used as tools to investigate the role of amylin aggregation in type II diabetes or as therapeutics in order to reduce β-cell damage. Interestingly, three of the compounds analyzed—benzbromarone, quercetin, and folic acid—are able to slow down amylin fiber formation according to Thioflavin T binding, turbidimetry, and Transmission Electron Microscopy assays. In addition to the in vitro assays, we have tested the effect of these compounds in an amyloid toxicity cell culture model and we have found that one of them, quercetin, has the ability to partly protect cultured pancreatic insulinoma cells from the cytotoxic effect of amylin. Our data suggests that quercetin can contribute to reduce oxidative damage in pancreatic insulinoma β cells by modulating the aggregation propensity of amylin.
11. Sex Pheromone Investigation of Anastrepha serpentina (Diptera: Tephritidae)
Science.gov (United States)
Attraction of virgin females to odor of calling males was demonstrated. This sex pheromone mediated attraction occurred during the latter half of a 13-h photophase but not during the first half of the day. Two major components of emissions of calling males, 2,5-dimethylpyrazine (DMP) and 2,5-dihyd...
12. Do perfume additives termed human pheromones warrant being termed pheromones?
Science.gov (United States)
Winman, Anders
2004-09-30
Two studies of the effects of perfume additives, termed human pheromones by the authors, have conveyed the message that these substances can promote an increase in human sociosexual behaviour [Physiol. Behav. 75 (2003) R1; Arch. Sex. Behav. 27 (1998) R2]. The present paper presents an extended analysis of this data. It is shown that in neither study is there a statistically significant increase in any of the sociosexual behaviours for the experimental groups. In the control groups of both studies, there are, however, moderate but statistically significant decreases in the corresponding behaviour. Most notably, there is no support in data for the claim that the substances increase the attractiveness of the wearers of the substances to the other sex. It is concluded that more research using matched homogenous groups of participants is needed. Copyright 2004 Elsevier Inc.
13. [Sex pheromone secondary components of Indian meal moth Plodia interpunctella in China. HU wenlil 2, DU].
Science.gov (United States)
Hu, Wenli; Du, Jiawei
2005-09-01
Indian meal moth Plodia interpunctella Hübner (Lepidoptera: Pyralidae) is considered as an important insect pest infesting stored grains and other products in China. The major sex pheromone component of P. interpunctella, Z9, E12-14: OAc (TDA), has already been identified. Though the efficiency of male capture by using the bait with this component alone is quite good, the pheromone system is far from fully understood. The identification with capillary chromatographic analysis and GC-MS methods showed that there were four main components, i. e., Z9, E12-14: OAc(A), Z9, E12-14: OH (B), Z9, E12-14: Ald(C), and Z9-14: OAc(D), in the sex pheromone gland of female P. interpunctella, and the ratio of these four components was A: B: C:D= 100:22: 12:9. Wind tunnel experimental results suggested that the response of male P. interpunctella to a blend (A: B: C: D = 8:2:1:0.8) was not significantly different from that to female sex pheromone gland extracts.
14. Sex versus sweet: opposite effects of opioid drugs on the reward of sucrose and sexual pheromones.
Science.gov (United States)
Agustín-Pavón, Carmen; Martínez-Ricós, Joana; Martínez-García, Fernando; Lanuza, Enrique
2008-04-01
Endogenous opioids mediate some reward processes involving both natural (food, sweet taste) and artificial (morphine, heroin) rewards. In contrast, sexual behavior (which is also reinforcing) is generally inhibited by opioids. To establish the role of endogenous opioids for a newly described natural reinforcer, namely male sexual pheromones for female mice, we checked the effects of systemic injections of the general opioid antagonist naloxone (1-10 mg/kg) and the agonist fentanyl (0.1- 0.5 mg/kg) in a number of behavioral tests. Naloxone affected neither the innate preference for male-soiled bedding (vs. female-soiled bedding) in 2-choice tests nor the induction of place conditioning using male pheromones as rewarding stimuli, although it effectively blocked the preference for consuming a sucrose solution. In contrast, fentanyl inhibited the preference for male chemosignals without altering sucrose preference. These results suggest that, in macrosmatic animals such as rodents, opioidergic inhibition of sexual behavior might be due, at least partially, to an impaired processing of pheromonal cues and that the hedonic value of sweet-tasting solutions and sexual pheromones are under different opioid modulation.
15. A sea lamprey (Petromyzon marinus) sex pheromone mixture increases trap catch relative to a single synthesized component in specific environments
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Johnson, Nicholas S.; Tix, John A.; Hlina, Benjamin L.; Wagner, C. Michael; Siefkes, Michael J.; Wang, Huiyong; Li, Weiming
2015-01-01
Spermiating male sea lamprey (Petromyzon marinus) release a sex pheromone, of which a component, 7α, 12α, 24-trihydoxy-3-one-5α-cholan-24-sulfate (3kPZS), has been identified and shown to induce long distance preference responses in ovulated females. However, other pheromone components exist, and when 3kPZS alone was used to control invasive sea lamprey populations in the Laurentian Great Lakes, trap catch increase was significant, but gains were generally marginal. We hypothesized that free-ranging sea lamprey populations discriminate between a partial and complete pheromone while migrating to spawning grounds and searching for mates at spawning grounds. As a means to test our hypothesis, and to test two possible uses of sex pheromones for sea lamprey control, we asked whether the full sex pheromone mixture released by males (spermiating male washings; SMW) is more effective than 3kPZS in capturing animals in traditional traps (1) en route to spawning grounds and (2) at spawning grounds. At locations where traps target sea lampreys en route to spawning grounds, SMW-baited traps captured significantly more sea lampreys than paired 3kPZS-baited traps (~10 % increase). At spawning grounds, no difference in trap catch was observed between 3kPZS and SMW-baited traps. The lack of an observed difference at spawning grounds may be attributed to increased pheromone competition and possible involvement of other sensory modalities to locate mates. Because fishes often rely on multiple and sometimes redundant sensory modalities for critical life history events, the addition of sex pheromones to traditionally used traps is not likely to work in all circumstances. In the case of the sea lamprey, sex pheromone application may increase catch when applied to specifically designed traps deployed in streams with low adult density and limited spawning habitat.
16. The Post-mating Switch in the Pheromone Response of Nasonia Females Is Mediated by Dopamine and Can Be Reversed by Appetitive Learning
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Maria Lenschow
2018-01-01
Full Text Available The olfactory sense is of crucial importance for animals, but their response to chemical stimuli is plastic and depends on their physiological state and prior experience. In many insect species, mating status influences the response to sex pheromones, but the underlying neuromodulatory mechanisms are poorly understood. After mating, females of the parasitic wasp Nasonia vitripennis are no longer attracted to the male sex pheromone. Here we show that this post-mating behavioral switch is mediated by dopamine (DA. Females fed a DA-receptor antagonist prior to mating maintained their attraction to the male pheromone after mating while virgin females injected with DA became unresponsive. However, the switch is reversible as mated females regained their pheromone preference after appetitive learning. Feeding mated N. vitripennis females with antagonists of either octopamine- (OA or DA-receptors prevented relearning of the pheromone preference suggesting that both receptors are involved in appetitive learning. Moreover, DA injection into mated females was sufficient to mimic the oviposition reward during odor conditioning with the male pheromone. Our data indicate that DA plays a key role in the plastic pheromone response of N. vitripennis females and reveal some striking parallels between insects and mammals in the neuromodulatory mechanisms underlying olfactory plasticity.
17. Two group A streptococcal peptide pheromones act through opposing Rgg regulators to control biofilm development.
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Jennifer C Chang
2011-08-01
Full Text Available Streptococcus pyogenes (Group A Streptococcus, GAS is an important human commensal that occasionally causes localized infections and less frequently causes severe invasive disease with high mortality rates. How GAS regulates expression of factors used to colonize the host and avoid immune responses remains poorly understood. Intercellular communication is an important means by which bacteria coordinate gene expression to defend against host assaults and competing bacteria, yet no conserved cell-to-cell signaling system has been elucidated in GAS. Encoded within the GAS genome are four rgg-like genes, two of which (rgg2 and rgg3 have no previously described function. We tested the hypothesis that rgg2 or rgg3 rely on extracellular peptides to control target-gene regulation. We found that Rgg2 and Rgg3 together tightly regulate two linked genes encoding new peptide pheromones. Rgg2 activates transcription of and is required for full induction of the pheromone genes, while Rgg3 plays an antagonistic role and represses pheromone expression. The active pheromone signals, termed SHP2 and SHP3, are short and hydrophobic (DI[I/L]IIVGG, and, though highly similar in sequence, their ability to disrupt Rgg3-DNA complexes were observed to be different, indicating that specificity and differential activation of promoters are characteristics of the Rgg2/3 regulatory circuit. SHP-pheromone signaling requires an intact oligopeptide permease (opp and a metalloprotease (eep, supporting the model that pro-peptides are secreted, processed to the mature form, and subsequently imported to the cytoplasm to interact directly with the Rgg receptors. At least one consequence of pheromone stimulation of the Rgg2/3 pathway is increased biogenesis of biofilms, which counteracts negative regulation of biofilms by RopB (Rgg1. These data provide the first demonstration that Rgg-dependent quorum sensing functions in GAS and substantiate the role that Rggs play as peptide
18. Evidence for a Nest Defense Pheromone in Bald-Faced Hornets, Dolichovespula Maculata, and Identification of Components.
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Jimenez, Sebastian Ibarra; Gries, Regine; Zhai, Huimin; Derstine, Nathan; McCann, Sean; Gries, Gerhard
2016-05-01
In eusocial insects like Bald-faced hornets, Dolichovespula maculata, nest defense is essential because nests contain a large number of protein-rich larvae and pupae, and thus are attractive to nest predators. Our objectives were to investigate whether D. maculata exhibit pheromone-mediated nest defense, and to identify and field test any pheromone components. We tested for pheromone-mediated nest defense behavior of D. maculata by placing a paired box-apparatus near the entrance of D. maculata nests, and treating both boxes with a solvent control, or one of the two boxes with a solvent control and the other with either venom sac extract, the putative source of nest defense pheromone, or synthetic pheromone. The sound impulses caused by nest mates attempting to sting or strike the boxes were recorded for 3 min. Compared to the double-control treatment, the number of strikes increased 27-fold when one of the two boxes was treated with venom sac extract, providing evidence for an alarm response. The box treated with venom sac extract also induced a significantly greater proportion of strikes than the corresponding control box, providing evidence for a target-oriented response. Analyzing venom sac extract by gas chromatographic-electroantennographic detection (GC-EAD) and GC-mass spectrometry resulted in the identification of seven candidate pheromone components: (a) dimethylaminoethanol, (b) dimethylamino ethyl acetate, (c) 2,5-dimethylpyrazine, (d) N-3-methylbutylacetamide, (e) 2-heptadecanone, (f) (Z)-8-heptadecen-2-one, and (g) (Z)-10-nonadecen-2-one. Testing in paired-box bioassays blends of the nitrogen-containing volatile components a-d, the less volatile ketones e-g, or both (a-g), indicated that a-d primarily have an alarm function. The ketones e-g, in contrast, induced target-oriented responses, possibly marking the box, or potential nest predators, for guided and concerted attacks, or enhancing the alarm-inducing effect of the volatile pheromone components
19. Evolution of moth sex pheromone composition by a single amino acid substitution in a fatty acid desaturase
Czech Academy of Sciences Publication Activity Database
Buček, Aleš; Matoušková, P.; Vogel, H.; Šebesta, Petr; Jahn, Ullrich; Weissflog, J.; Svatoš, Aleš; Pichová, Iva
2015-01-01
Roč. 112, č. 41 (2015), s. 12586-12591 ISSN 0027-8424 R&D Projects: GA MŠk LO1302 Institutional support: RVO:61388963 Keywords : fatty acid desaturase * Manduca sexta * sex pheromone biosynthesis * pheromone evolution * substrate specificity Subject RIV: CC - Organic Chemistry Impact factor: 9.423, year: 2015
20. Bioaccessible Porosity in Soil Aggregates and Implications for Biodegradation of High Molecular Weight Petroleum Compounds.
Science.gov (United States)
Akbari, Ali; Ghoshal, Subhasis
2015-12-15
We evaluated the role of soil aggregate pore size on biodegradation of essentially insoluble petroleum hydrocarbons that are biodegraded primarily at the oil-water interface. The size and spatial distribution of pores in aggregates sampled from biodegradation experiments of a clayey, aggregated, hydrocarbon-contaminated soil with relatively high bioremediation end point were characterized by image analyses of X-ray micro-CT scans and N2 adsorption. To determine the bioaccessible pore sizes, we performed separate experiments to assess the ability of hydrocarbon degrading bacteria isolated from the soil to pass through membranes with specific sized pores and to access hexadecane (model insoluble hydrocarbon). Hexadecane biodegradation occurred only when pores were 5 μm or larger, and did not occur when pores were 3 μm and smaller. In clayey aggregates, ∼ 25% of the aggregate volume was attributed to pores larger than 4 μm, which was comparable to that in aggregates from a sandy, hydrocarbon-contaminated soil (~23%) scanned for comparison. The ratio of volumes of inaccessible pores (4 μm) in the clayey aggregates was 0.32, whereas in the sandy aggregates it was approximately 10 times lower. The role of soil microstructure on attainable bioremediation end points could be qualitatively assessed in various soils by the aggregate characterization approach outlined herein.
1. Development of a pheromone elution rate physical model
Science.gov (United States)
M.E. Teske; H.W. Thistle; B.L. Strom; H. Zhu
2015-01-01
A first principle modeling approach has been applied to available data describing the elution of semiochemicals from pheromone dispensers. These data included field data for 27 products developed by several manufacturers, including homemade devices, as well as environmental chamber data collected on three semiochemical products. The goal of this effort was to...
2. Regulation of Isoprenoid Pheromone Biosynthesis in Bumblebee Males
Czech Academy of Sciences Publication Activity Database
Prchalová, Darina; Buček, Aleš; Brabcová, Jana; Žáček, Petr; Kindl, Jiří; Valterová, Irena; Pichová, Iva
2016-01-01
Roč. 17, č. 3 (2016), s. 260-267 ISSN 1439-4227 R&D Projects: GA MŠk LO1302; GA ČR GA15-06569S Institutional support: RVO:61388963 Keywords : biosynthesis * Bombus spp. * gene expression * isoprenoid s * pheromones * transcriptional regulation Subject RIV: CE - Biochemistry Impact factor: 2.847, year: 2016
3. A reference gene set for sex pheromone biosynthesis and degradation genes from the diamondback moth, Plutella xylostella, based on genome and transcriptome digital gene expression analyses.
Science.gov (United States)
He, Peng; Zhang, Yun-Fei; Hong, Duan-Yang; Wang, Jun; Wang, Xing-Liang; Zuo, Ling-Hua; Tang, Xian-Fu; Xu, Wei-Ming; He, Ming
2017-03-01
Female moths synthesize species-specific sex pheromone components and release them to attract male moths, which depend on precise sex pheromone chemosensory system to locate females. Two types of genes involved in the sex pheromone biosynthesis and degradation pathways play essential roles in this important moth behavior. To understand the function of genes in the sex pheromone pathway, this study investigated the genome-wide and digital gene expression of sex pheromone biosynthesis and degradation genes in various adult tissues in the diamondback moth (DBM), Plutella xylostella, which is a notorious vegetable pest worldwide. A massive transcriptome data (at least 39.04 Gb) was generated by sequencing 6 adult tissues including male antennae, female antennae, heads, legs, abdomen and female pheromone glands from DBM by using Illumina 4000 next-generation sequencing and mapping to a published DBM genome. Bioinformatics analysis yielded a total of 89,332 unigenes among which 87 transcripts were putatively related to seven gene families in the sex pheromone biosynthesis pathway. Among these, seven [two desaturases (DES), three fatty acyl-CoA reductases (FAR) one acetyltransferase (ACT) and one alcohol dehydrogenase (AD)] were mainly expressed in the pheromone glands with likely function in the three essential sex pheromone biosynthesis steps: desaturation, reduction, and esterification. We also identified 210 odorant-degradation related genes (including sex pheromone-degradation related genes) from seven major enzyme groups. Among these genes, 100 genes are new identified and two aldehyde oxidases (AOXs), one aldehyde dehydrogenase (ALDH), five carboxyl/cholinesterases (CCEs), five UDP-glycosyltransferases (UGTs), eight cytochrome P450 (CYP) and three glutathione S-transferases (GSTs) displayed more robust expression in the antennae, and thus are proposed to participate in the degradation of sex pheromone components and plant volatiles. To date, this is the most
4. Avoidance and contextual learning induced by a kairomone, a pheromone and a common odorant in female CD1 mice
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Lluís eFortes-Marco
2015-10-01
Full Text Available Chemosignals mediate both intra- and inter-specific communication in most mammals. Pheromones elicit stereotyped reactions in conspecifics, whereas kairomones provoke a reaction in an allospecific animal. For instance, predator kairomones elicit anticipated defensive responses in preys. The aim of this work was to test the behavioral responses of female mice to two chemosignals: 2-heptanone (2-HP, a putative alarm pheromone, and 2,4,5-trimethylthiazoline (TMT, a fox-derived putative kairomone, widely used to investigate fear and anxiety in rodents. The banana-like odorant isoamyl acetate (IA, unlikely to act as a chemosignal, served as a control odorant. We first presented increasing amounts of these odorants in consecutive days, in a test box in which mice could explore or avoid them. Female mice avoided the highest amounts of all three compounds, with TMT and IA eliciting avoidance at lower amounts (3.8 pmol and 0.35 μmol, respectively than 2-HP (35 μmol. All three compounds induced minimal effects in global locomotion and immobility in this set up. Further, mice detected 3.5 pmol of TMT and IA in a habituation-dishabituation test, so avoidance of IA started well beyond the detection threshold. Finally, both TMT and IA, but not 2-HP, induced conditioned place avoidance and increased immobility in the neutral compartment during a contextual memory test. These data suggest that intense odors can induce contextual learning irrespective of their putative biological significance. Our results support that synthetic predator-related compounds (like TMT or other intense odorants are useful to investigate the neurobiological basis of emotional behaviors in rodents. Since intense odorants unlikely to act as chemosignals can elicit similar behavioral reactions than chemosignals, we stress the importance of using behavioral measures in combination with other physiological (e.g. hormonal levels or neural measures (e.g. immediate early gene expression to
5. Mimicking Insect Communication: Release and Detection of Pheromone, Biosynthesized by an Alcohol Acetyl Transferase Immobilized in a Microreactor
NARCIS (Netherlands)
Munoz, L.; Dimov, N.G.; Carot-Sans, G.; Bula, W.P.; Guerrero, A.; Gardeniers, Johannes G.E.
2012-01-01
Infochemical production, release and detection of (Z,E)-9,11-tetradecadienyl acetate, the major component of the pheromone of the moth Spodoptera littoralis, is achieved in a novel microfluidic system designed to mimic the final step of the pheromone biosynthesis by immobilized recombinant alcohol
6. Sampling gravid Culex quinquefasciatus (Diptera: Culicidae) in Tanzania with traps baited with synthetic oviposition pheromone and grass infusions
NARCIS (Netherlands)
Mboera, L.E.G.; Takken, W.; Mdira, K.Y.; Pickett, J.A.
2000-01-01
The effectiveness of traps baited with (5R,6S)-6-acetoxy-5-hexadecanolide (the synthetic oviposition pheromone) and grass infusions in sampling a population of gravid Culex quinquefasciatus Say was conducted in Muheza, Northeast Tanzania. A counterflow geometry (CFG) trap baited with pheromone and
7. Gqalpha-linked PLCbeta and PLCgamma are essential components of the pheromone biosynthesis activating neuropeptide (PBAN) signal transduction cascade
Science.gov (United States)
Sex pheromone production for most moths is regulated by pheromone biosynthesis activating neuropeptide (PBAN). In Bombyx mori, PBAN binding triggers the opening of store-operated Ca2+ channels, suggesting the involvement of a receptor-activated phospholipase C (PLC). In this study, we found that P...
8. Gypsy moth (Lepidoptera: Lymantriidae) flight behavior and phenology based on field-deployed automated pheromone-baited traps
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Patrick C. Tobin; Kenneth T. Klein; Donna S. Leonard
2009-01-01
Populations of the gypsy moth, Lymantria dispar (L.), are extensively monitored in the United States through the use of pheromone-baited traps.We report on use of automated pheromone-baited traps that use a recording sensor and data logger to record the unique date-time stamp of males as they enter the trap.We deployed a total of 352 automated traps...
9. Variation in sex pheromone emission does not reflect immunocompetence but affects attractiveness of male burying beetles-a combination of laboratory and field experiments.
Science.gov (United States)
Chemnitz, Johanna; Bagrii, Nadiia; Ayasse, Manfred; Steiger, Sandra
2017-08-01
Life history theory predicts a trade-off between male sexual trait expression and immunocompetence. Using burying beetles, Nicrophorus vespilloides, as a model, we investigated the relationship between male immune function, sex pheromone emission, and attractiveness under field conditions. In the first experiment, we tested whether there is a positive correlation between immune capacity, sex pheromone characteristics (quantity, relative composition, and time invested in pheromone emission), and male attractiveness. As a measurement of immune capacity, we used an individual's encapsulation ability against a novel antigen. In the second experiment, we specifically examined whether a trade-off between chemical trait expression and immune function existed. To this end, we challenged the immune system and measured the subsequent investment in sex pheromone emission and the attractiveness of the male under field conditions. We found that a male's immunocompetence was neither related to the emission of the male's sex pheromone nor to its attractiveness in the field. Furthermore, none of the immune-challenge treatments affected the subsequent investment in pheromone emission or number of females attracted. However, we showed that the same males that emitted a high quantity of their sex pheromone in the laboratory were able to attract more females in the field. Our data suggest that the chemical signal is not a reliable predictor of a male's immunocompetence but rather is a general important fitness-related trait, with a higher emission of the sex pheromone measured in the laboratory directly affecting the attractiveness of a male under field conditions.
10. Variation in sex pheromone emission does not reflect immunocompetence but affects attractiveness of male burying beetles—a combination of laboratory and field experiments
Science.gov (United States)
Chemnitz, Johanna; Bagrii, Nadiia; Ayasse, Manfred; Steiger, Sandra
2017-08-01
Life history theory predicts a trade-off between male sexual trait expression and immunocompetence. Using burying beetles, Nicrophorus vespilloides, as a model, we investigated the relationship between male immune function, sex pheromone emission, and attractiveness under field conditions. In the first experiment, we tested whether there is a positive correlation between immune capacity, sex pheromone characteristics (quantity, relative composition, and time invested in pheromone emission), and male attractiveness. As a measurement of immune capacity, we used an individual's encapsulation ability against a novel antigen. In the second experiment, we specifically examined whether a trade-off between chemical trait expression and immune function existed. To this end, we challenged the immune system and measured the subsequent investment in sex pheromone emission and the attractiveness of the male under field conditions. We found that a male's immunocompetence was neither related to the emission of the male's sex pheromone nor to its attractiveness in the field. Furthermore, none of the immune-challenge treatments affected the subsequent investment in pheromone emission or number of females attracted. However, we showed that the same males that emitted a high quantity of their sex pheromone in the laboratory were able to attract more females in the field. Our data suggest that the chemical signal is not a reliable predictor of a male's immunocompetence but rather is a general important fitness-related trait, with a higher emission of the sex pheromone measured in the laboratory directly affecting the attractiveness of a male under field conditions.
11. Old maids have more appeal: effects of age and pheromone source on mate attraction in an orb-web spider
Directory of Open Access Journals (Sweden)
Anna-Lena Cory
2016-04-01
Full Text Available Background. In many insects and spider species, females attract males with volatile sex pheromones, but we know surprisingly little about the costs and benefits of female pheromone emission. Here, we test the hypothesis that mate attraction by females is dynamic and strategic in the sense that investment in mate attraction is matched to the needs of the female. We use the orb-web spider Argiope bruennichi in which females risk the production of unfertilised egg clutches if they do not receive a copulation within a certain time-frame. Methods. We designed field experiments to compare mate attraction by recently matured (young females with females close to oviposition (old. In addition, we experimentally separated the potential sources of pheromone transmission, namely the female body and the web silk. Results. In accordance with the hypothesis of strategic pheromone production, the probability of mate attraction and the number of males attracted differed between age classes. While the bodies and webs of young females were hardly found by males, the majority of old females attracted up to two males within two hours. Old females not only increased pheromone emission from their bodies but also from their webs. Capture webs alone spun by old females were significantly more efficient in attracting males than webs of younger females. Discussion. Our results suggest that females modulate their investment in signalling according to the risk of remaining unmated and that they thereby economize on the costs associated with pheromone production and emission.
12. Old maids have more appeal: effects of age and pheromone source on mate attraction in an orb-web spider.
Science.gov (United States)
Cory, Anna-Lena; Schneider, Jutta M
2016-01-01
Background. In many insects and spider species, females attract males with volatile sex pheromones, but we know surprisingly little about the costs and benefits of female pheromone emission. Here, we test the hypothesis that mate attraction by females is dynamic and strategic in the sense that investment in mate attraction is matched to the needs of the female. We use the orb-web spider Argiope bruennichi in which females risk the production of unfertilised egg clutches if they do not receive a copulation within a certain time-frame. Methods. We designed field experiments to compare mate attraction by recently matured (young) females with females close to oviposition (old). In addition, we experimentally separated the potential sources of pheromone transmission, namely the female body and the web silk. Results. In accordance with the hypothesis of strategic pheromone production, the probability of mate attraction and the number of males attracted differed between age classes. While the bodies and webs of young females were hardly found by males, the majority of old females attracted up to two males within two hours. Old females not only increased pheromone emission from their bodies but also from their webs. Capture webs alone spun by old females were significantly more efficient in attracting males than webs of younger females. Discussion. Our results suggest that females modulate their investment in signalling according to the risk of remaining unmated and that they thereby economize on the costs associated with pheromone production and emission.
13. Pheromone evolution, reproductive genes, and comparative transcriptomics in mediterranean earthworms (annelida, oligochaeta, hormogastridae).
Science.gov (United States)
Novo, Marta; Riesgo, Ana; Fernández-Guerra, Antoni; Giribet, Gonzalo
2013-07-01
Animals inhabiting cryptic environments are often subjected to morphological stasis due to the lack of obvious agents driving selection, and hence chemical cues may be important drivers of sexual selection and individual recognition. Here, we provide a comparative analysis of de novo-assembled transcriptomes in two Mediterranean earthworm species with the objective to detect pheromone proteins and other reproductive genes that could be involved in cryptic speciation processes, as recently characterized in other earthworm species. cDNA libraries of unspecific tissue of Hormogaster samnitica and three different tissues of H. elisae were sequenced in an Illumina Genome Analyzer II or Hi-Seq. Two pheromones, Attractin and Temptin were detected in all tissue samples and both species. Attractin resulted in a reliable marker for phylogenetic inference. Temptin contained multiple paralogs and was slightly overexpressed in the digestive tissue, suggesting that these pheromones could be released with the casts. Genes involved in sexual determination and fertilization were highly expressed in reproductive tissue. This is thus the first detailed analysis of the molecular machinery of sexual reproduction in earthworms.
14. An Alien in the Group: Eusocial Male Bees Sharing Nonspecific Reproductive Aggregations
Science.gov (United States)
dos Santos, C. F.; Ferreira-Caliman, M. J.; Nascimento, F. S.
2015-01-01
Sexual selection predicts that individuals competing for access to sexual partners should maximize their chances of mating by looking for sites where the chances of finding partners are more likely to occur. However, males of stingless bees have been observed sharing nonspecific reproductive aggregations. This uncommon behavior appears to confer no obvious increase of individual fitness. It has been suggested that this reproductive strategy is due to the similarity between male odors common to different stingless bee species. Cuticular hydrocarbons (CHCs) are candidate odors of interest because their nonvolatile pheromone nature allows them to play an important role in sexual behavior and species recognition. Here, we review the literature to evaluate whether any phylogenetic patterns exist among male stingless bees that aggregate with closely or distantly related species. We also compared the CHC profiles of males of Neotropical stingless bee species (Plebeia sp. Schwarz, Trigona spinipes (F.), Tetragona clavipes (F.), Nannotrigona testaceicornis (Lepeletier), Scaptotrigona aff. depilis (Moure), Tetragonisca angustula (Latreille), and Melipona subnitida (Ducke) to reveal any chemical similarities among their male odors. We found males of 21 stingless bee species involved in interspecific interactions mainly from Neotropical and Indo-Malayan/Australasian regions. Alien males did not necessarily visit host aggregations of closely related species. Furthermore, the CHC profiles of different studied species were very distinct from each other and do not overlapped at all. It is unclear yet why this apparently nonadaptive behavior carried out by some stingless bee males. PMID:26518220
15. ELECTROSPUN MESOFIBERS, A NOVEL BIODEGRADABLE PHEROMONE DISPENSER TECHNOLOGY, ARE COMBINED WITH MECHANICAL DEPLOYMENT FOR EFFICIENT IPM OF LOBESIA BOTRANA IN VINEYARDS.
Science.gov (United States)
Hummel, Hans E; Langner, S S; Breuer, M
2015-01-01
Behaviour modifying pheromones are well known agents for disrupting mating communication of pest insects. For optimal activity, they must be dispensed in time and space at a quantitatively measurable, predetermined release rate covering the flight period of the target species. Pheromones appeal to environmentally conscientious entomologists for their biodegradability, non-toxicity and ecological compatibility. In attempts of combining the virtues of pheromones, suitable slow release dispensers, and their mechanical deployment, an ecologically sensible, reasonably priced and patented procedure was developed and tested with the vineyard pest Lobesia botrana (Lep.: Tortricidae). It is characterized by (1) Electrospun mesofibers with diameters ranging from 0.6 to 3.5 micrometres, containing disruptants and dispensing it by slow release diffusion into the crop, (2) simultaneous application of the fully biodegradable combination of pheromone with Ecoflex polyester mesofiber, (3) combination of mechanical deployment by multi-purpose cultivators of the prefabricated pheromone dispensers with other simultaneous cultivation measures, and thus further reducing labour time and treatment costs. The dispensers are biodegradable within half a year without leaving any objectionable residues. In the standard eco-toxicology tests pheromone dispensers are harmless to non-target organisms. The disruptive effect of one treatment lasts for seven weeks which covers well one of several flight periods of L. botrana.
16. Innate recognition of pheromone and food odors in moths: a common mechanism in the antennal lobe?
Directory of Open Access Journals (Sweden)
Joshua P Martin
2010-09-01
Full Text Available The survival of an animal often depends on an innate response to a particular sensory stimulus. For an adult male moth, two categories of odors are innately attractive: pheromone released by conspecific females, and the floral scents of certain, often co-evolved, plants. These odors consist of multiple volatiles in characteristic mixtures. Here, we review evidence that both categories of odors are processed as sensory objects, and we suggest a mechanism in the primary olfactory center, the antennal lobe (AL, that encodes the configuration of these mixtures and may underlie recognition of innately attractive odors. In the pheromone system, mixtures of two or three volatiles elicit upwind flight. Peripheral changes are associated with behavioral changes in speciation, and suggest the existence of a pattern recognition mechanism for pheromone mixtures in the AL. Moths are similarly innately attracted to certain floral scents. Though floral scents consist of multiple volatiles that activate a broad array of receptor neurons, only a smaller subset, numerically comparable to pheromone mixtures, is necessary and sufficient to elicit behavior. Both pheromone and floral scent mixtures that produce attraction to the odor source elicit synchronous action potentials in particular populations of output (projection neurons (PNs in the AL. We propose a model in which the synchronous output of a population of PNs encodes the configuration of an innately attractive mixture, and thus comprises an innate mechanism for releasing odor-tracking behavior. The particular example of olfaction in moths may inform the general question of how sensory objects trigger innate responses.
17. Site of pheromone biosynthesis and isolation of HMG-CoA reductase cDNA in the cotton boll weevil, Anthonomus grandis.
Science.gov (United States)
Taban, A Huma; Fu, Jessica; Blake, Jacob; Awano, Ami; Tittiger, Claus; Blomquist, Gary J
2006-08-01
Isolated gut tissue from male cotton boll weevil, Anthonomus grandis (Coleoptera: Curculionidae), incorporated radiolabeled acetate into components that co-eluted with monoterpenoid pheromone components on HPLC. This demonstrates that pheromone components of male A. grandis are produced de novo and strongly suggests that pheromone biosynthesis occurs in gut tissue. A central enzyme in isoprenoid biosynthesis is 3-hydroxy-3-methylglutaryl-CoA reductase (HMG-R), and a full-length HMG-R cDNA was isolated from A. grandis. The predicted translation product was 54 and 45% identical to HMG-R from Ips paraconfusus and Drosophila melanogaster, respectively. HMG-R gene expression gradually increased with age in male A. grandis, which correlates with pheromone production. However, topical application of JH III did not significantly increase HMG-R mRNA levels.
18. Aggregate exposure to common fragrance compounds: Comparison of the contribution of essential oils and cosmetics using probabilistic methods and the example of limonene.
Science.gov (United States)
Dornic, N; Roudot, A C; Batardière, A; Nedelec, A S; Bourgeois, P; Hornez, N; Le Caer, F; Ficheux, A S
2018-04-09
The knowledge of aggregate exposure to different types of products is paramount in the risk assessment. The aim of this study was to compare the relative contribution of essential oils compared to cosmetics on the daily dermal exposure to limonene, an ubiquitous fragrance compound that can be an allergen depending on its degree of oxidation. Aggregate daily exposure to limonene was calculated among a panel of French volunteers using both essential oils and cosmetics, for 4 different specific zones, i.e. face and neck, chest, upper limbs and lower limbs. Calculations were made using a probabilistic Monte Carlo method and sensitivity analysis. The main strength of this work was the inclusion of essential oils in addition to cosmetics in the model. For the first time, the generated data could be used to compare the contribution of these two products in dermal exposure. Essential oils appear to be significant contributors to exposure to limonene particularly for the face. This work is a first step that will permit to determine the exposure to other fragrance compounds with sensitizing potential. These data will be useful for risk managers to consider the inclusion of essential oils in the overall burden of this pathology. Copyright © 2018 Elsevier Ltd. All rights reserved.
19. Curcumin inhibits aggregation of alpha-synuclein.
Science.gov (United States)
Pandey, Neeraj; Strider, Jeffrey; Nolan, William C; Yan, Sherry X; Galvin, James E
2008-04-01
Aggregation of amyloid-beta protein (Abeta) is a key pathogenic event in Alzheimer's disease (AD). Curcumin, a constituent of the Indian spice Turmeric is structurally similar to Congo Red and has been demonstrated to bind Abeta amyloid and prevent further oligomerization of Abeta monomers onto growing amyloid beta-sheets. Reasoning that oligomerization kinetics and mechanism of amyloid formation are similar in Parkinson's disease (PD) and AD, we investigated the effect of curcumin on alpha-synuclein (AS) protein aggregation. In vitro model of AS aggregation was developed by treatment of purified AS protein (wild-type) with 1 mM Fe3+ (Fenton reaction). It was observed that the addition of curcumin inhibited aggregation in a dose-dependent manner and increased AS solubility. The aggregation-inhibiting effect of curcumin was next investigated in cell culture utilizing catecholaminergic SH-SY5Y cell line. A model system was developed in which the red fluorescent protein (DsRed2) was fused with A53T mutant of AS and its aggregation examined under different concentrations of curcumin. To estimate aggregation in an unbiased manner, a protocol was developed in which the images were captured automatically through a high-throughput cell-based screening microscope. The obtained images were processed automatically for aggregates within a defined dimension of 1-6 microm. Greater than 32% decrease in mutant alpha-synuclein aggregation was observed within 48 h subsequent to curcumin addition. Our data suggest that curcumin inhibits AS oligomerization into higher molecular weight aggregates and therefore should be further explored as a potential therapeutic compound for PD and related disorders.
20. The evolution of honest queen pheromones in insect societies
DEFF Research Database (Denmark)
van Zweden, Jelle Stijn
2010-01-01
of their ovaries and by preventing other workers from reproducing (worker policing). However, what maintains the honesty of such queen pheromones is still under discussion. The explanation that an honest queen signal evolves simply because it serves the interest of all colony members does not seem to hold, since...
1. Changes in pheromone production, release, mating behaviour and reproductive ability of the gamma-irradiated cockroach Nauphoeta cinerea (Olivier)
International Nuclear Information System (INIS)
Menon, M.
1978-01-01
Mature males of Nauphoeta cinerea produce a sex pheromone 'seducin' which has short-range effects in attracting mature females of the same species. Exposure of newly-emerged adult males to 3.5, 7, 14 or 21 krad of gamma-radiation decreased their life expectancy and affected their mating behaviour. Bioassay of dichloromethane extracts of males showed that radiation doses (14 krad) sufficient to induce sterility did not affect the ability to produce pheromone but significantly reduced the release of pheromone by inhibiting wing-raising. The sterile-male technique using males sterilized by ionizing radiation in air may not be the method of choice for control of Nauphoeta cinerea. (author)
2. Molecular characterization of pheromone biosynthesis activating neuropeptide from the diamondback moth, Plutella xylostella (L.).
Science.gov (United States)
Lee, Dae-Weon; Boo, Kyung Saeng
2005-12-01
Pheromone biosynthesis activating neuropeptide (PBAN) produced in the subesophageal ganglion stimulates pheromone production in the pheromone gland. A cDNA isolated from female adult heads of the diamondback moth (Plutella xylostella (L.)) encodes 193 amino acids including PBAN, designated as Plx-PBAN, and four other neuropeptides (NPs): diapause hormone (DH) homologue, alpha-NP, beta-NP and gamma-NP. All of the peptides are amidated in their C-termini and shared a conserved motif, FXPR(or K)L structure, as reported from other PBAN cDNAs. Plx-PBAN consists of 30 amino acids, the shortest PBAN so far reported. Plx-PBAN exhibited below 50% homology, compared with other known PBANs. The Plx-DH homologue is structurally different from DH of Bombyx mori. The length of Plx-beta-NP (16 amino acids) was the shortest and showed relatively low similarity, whereas gamma-NP (10 amino acids in length) was the longest among examined gamma-NPs. When female adults were injected with synthetic Plx-PBAN, pheromone production showed a maximal increase 1h post-injection. RT-PCR screening revealed that Plx-PBAN cDNA was expressed in all examined body parts, with the highest expression level in the head of female adults. Analysis of RT-PCR products indicated the Plx-PBAN sequence was identical in all examined body parts of both sexes. Phylogenetic analysis revealed that the Plx-PBAN gene is distantly related to other PBANs, demonstrated by the relatively low similarity.
3. Quantitative Trait Locus Analysis of Mating Behavior and Male Sex Pheromones in Nasonia Wasps
Directory of Open Access Journals (Sweden)
Wenwen Diao
2016-06-01
Full Text Available A major focus in speciation genetics is to identify the chromosomal regions and genes that reduce hybridization and gene flow. We investigated the genetic architecture of mating behavior in the parasitoid wasp species pair Nasonia giraulti and Nasonia oneida that exhibit strong prezygotic isolation. Behavioral analysis showed that N. oneida females had consistently higher latency times, and broke off the mating sequence more often in the mounting stage when confronted with N. giraulti males compared with males of their own species. N. oneida males produce a lower quantity of the long-range male sex pheromone (4R,5S-5-hydroxy-4-decanolide (RS-HDL. Crosses between the two species yielded hybrid males with various pheromone quantities, and these males were used in mating trials with females of either species to measure female mate discrimination rates. A quantitative trait locus (QTL analysis involving 475 recombinant hybrid males (F2, 2148 reciprocally backcrossed females (F3, and a linkage map of 52 equally spaced neutral single nucleotide polymorphism (SNP markers plus SNPs in 40 candidate mating behavior genes revealed four QTL for male pheromone amount, depending on partner species. Our results demonstrate that the RS-HDL pheromone plays a role in the mating system of N. giraulti and N. oneida, but also that additional communication cues are involved in mate choice. No QTL were found for female mate discrimination, which points at a polygenic architecture of female choice with strong environmental influences.
4. Pheromonal regulation of starvation resistance in honey bee workers ( Apis mellifera)
Science.gov (United States)
Fischer, Patrick; Grozinger, Christina M.
2008-08-01
Most animals can modulate nutrient storage pathways according to changing environmental conditions, but in honey bees nutrient storage is also modulated according to changing behavioral tasks within a colony. Specifically, bees involved in brood care (nurses) have higher lipid stores in their abdominal fat bodies than forager bees. Pheromone communication plays an important role in regulating honey bee behavior and physiology. In particular, queen mandibular pheromone (QMP) slows the transition from nursing to foraging. We tested the effects of QMP exposure on starvation resistance, lipid storage, and gene expression in the fat bodies of worker bees. We found that indeed QMP-treated bees survived much longer compared to control bees when starved and also had higher lipid levels. Expression of vitellogenin RNA, which encodes a yolk protein that is found at higher levels in nurses than foragers, was also higher in the fat bodies of QMP-treated bees. No differences were observed in expression of genes involved in insulin signaling pathways, which are associated with nutrient storage and metabolism in a variety of species; thus, other mechanisms may be involved in increasing the lipid stores. These studies demonstrate that pheromone exposure can modify nutrient storage pathways and fat body gene expression in honey bees and suggest that chemical communication and social interactions play an important role in altering metabolic pathways.
5. Artificial pheromone for path selection by a foraging swarm of robots.
Science.gov (United States)
Campo, Alexandre; Gutiérrez, Alvaro; Nouyan, Shervin; Pinciroli, Carlo; Longchamp, Valentin; Garnier, Simon; Dorigo, Marco
2010-11-01
Foraging robots involved in a search and retrieval task may create paths to navigate faster in their environment. In this context, a swarm of robots that has found several resources and created different paths may benefit strongly from path selection. Path selection enhances the foraging behavior by allowing the swarm to focus on the most profitable resource with the possibility for unused robots to stop participating in the path maintenance and to switch to another task. In order to achieve path selection, we implement virtual ants that lay artificial pheromone inside a network of robots. Virtual ants are local messages transmitted by robots; they travel along chains of robots and deposit artificial pheromone on the robots that are literally forming the chain and indicating the path. The concentration of artificial pheromone on the robots allows them to decide whether they are part of a selected path. We parameterize the mechanism with a mathematical model and provide an experimental validation using a swarm of 20 real robots. We show that our mechanism favors the selection of the closest resource is able to select a new path if a selected resource becomes unavailable and selects a newly detected and better resource when possible. As robots use very simple messages and behaviors, the system would be particularly well suited for swarms of microrobots with minimal abilities.
6. The adipokinetic hormone receptor modulates sexual behavior, pheromone perception and pheromone production in a sex-specific and starvation-dependent manner in Drosophila melanogaster
Directory of Open Access Journals (Sweden)
Sebastien eLebreton
2016-01-01
Full Text Available Food availability and nutritional status shape the reproductive activity of many animals. In rodents, hormones such as gonadotropin-releasing hormone (GnRH, restore energy homeostasis not only through regulating e.g. caloric intake and energy housekeeping, but also through modulating sex drive. We investigated whether the insect homologue of the GnRH receptor, the adipokinetic hormone receptor (AKHR modulates sexual behavior of the fruit fly Drosophila melanogaster depending on nutritional status. We found that AKHR regulates male, but not female sexual behavior in a starvation-dependent manner. Males lacking AKHR showed a severe decrease in their courtship activity when starved, as well as an increase in mating duration when fed. AKHR expression is particularly strong in the subesophageal zone (SEZ, Ito et al. 2014. We found axonal projections from AKHR-expressing neurons to higher brain centers including specific glomeruli in the antennal lobe. Among the glomeruli that received projections were those dedicated to detecting the male specific pheromone cis-vaccenyl acetate (cVA. Accordingly, responses to cVA were dependent on the nutritional status of flies. AKHR was also involved in the regulation of the production of cuticular pheromones, 7,11-heptacosadiene and 7-tricosene. This effect was observed only in females and depended on their feeding state. AKHR has therefore a dual role on both pheromone perception and production. For the first time our study shows an effect of AKHR on insect sexual behavior and physiology. Our results support the hypothesis of a conserved role of the GnRH/AKH pathway on a nutritional state-dependent regulation of reproduction in both vertebrates and invertebrates.
7. Age-dependent plasticity of sex pheromone response in the moth, Agrotis ipsilon: combined effects of octopamine and juvenile hormone
DEFF Research Database (Denmark)
Jarriault, David; Barrozo, Romina B; de Carvalho Pinto, Carlos J
2009-01-01
Male moths use sex pheromones to find their mating partners. In the moth, Agrotis ipsilon, the behavioral response and the neuron sensitivity within the primary olfactory centre, the antennal lobe (AL), to sex pheromone increase with age and juvenile hormone (JH) biosynthesis. By manipulating...
8. Aphrodisiac Pheromone and its role in mating behaviour of Gamma irradiated SPODOPTERA LITTORALIS (BOISD.)
International Nuclear Information System (INIS)
ALM EL-DIN, M.M.S.; HAZAA, M.A.M.; EL-SHALL, S.S.A.
2007-01-01
The aphrodisiac pheromone in male moth of the cotton leaf worm, Spodoptera littoralis, is secreted from a scent gland that lies in the fore wings and hair pencils. The damage of the gland by gamma irradiation or elimination of the fore wings reduced mating percentage and the other related mating aspects. Multiple mating seldom was occurred in the eliminated wing males and this mean that the wing gland was effective in mating behaviour. The knowledge on pheromone glands and their role in mating behaviour have been appeared to be essential in the integrated control programmes
9. Coincidence of pheromone and plant odor leads to sensory plasticity in the heliothine olfactory system.
Directory of Open Access Journals (Sweden)
Elena Ian
Full Text Available Male moths possess a highly specialized olfactory system comprised of two segregated sub-arrangements dedicated to processing information about plant odors and pheromones, respectively. Communication between these two sub-systems has been described at the peripheral level, but relatively little is known about putative interactions at subsequent synaptic relays. The male moth faces the challenge of seeking out the conspecific female in a highly dynamic odor world. The female-produced pheromone blend, which is a limited resource serving as guidance for the male, will reach his antennae in intermittent pockets of odor filaments mixed with volatiles from various plants. In the present study we performed calcium imaging for measuring odor-evoked responses in the uni-glomerular antennal-lobe projection neurons (analog to mitral cells in the vertebrate olfactory bulb of Helicoverpa armigera. In order to investigate putative interactions between the two sub-systems tuned to plant volatiles and pheromones, respectively, we performed repeated stimulations with a selection of biologically relevant odors. We found that paired stimulation with a plant odor and the pheromone led to suppressed responses in both sub-systems as compared to those evoked during initial stimulation including application of each odor stimulus alone. The fact that the suppression persisted also after pairing, indicates the existence of a Hebbian-like plasticity in the primary olfactory center established by temporal pairing of the two odor stimulation categories.
10. CMPH: a multivariate phase-type aggregate loss distribution
Directory of Open Access Journals (Sweden)
Ren Jiandong
2017-12-01
Full Text Available We introduce a compound multivariate distribution designed for modeling insurance losses arising from different risk sources in insurance companies. The distribution is based on a discrete-time Markov Chain and generalizes the multivariate compound negative binomial distribution, which is widely used for modeling insurance losses.We derive fundamental properties of the distribution and discuss computational aspects facilitating calculations of risk measures of the aggregate loss, as well as allocations of the aggregate loss to individual types of risk sources. Explicit formulas for the joint moment generating function and the joint moments of different loss types are derived, and recursive formulas for calculating the joint distributions given. Several special cases of particular interest are analyzed. An illustrative numerical example is provided.
11. Management of Cosmopolites sordidus and Metamasius hemipterus in banana by pheromone-based mass trapping.
Science.gov (United States)
Alpizar, D; Fallas, M; Oehlschlager, A C; Gonzalez, L M
2012-03-01
Mass trapping Cosmopolites sordidus (Coleoptera, Curculionidae) using a pheromone-baited pitfall trap and Metamasius hemipterus (Coleoptera, Curculionidae) using a pheromone-sugarcane-baited open gallon trap was conducted in commercial banana. Four traps for each insect per hectare were placed in each of two 5-hectare plots of banana. Two additional 5-hectare plots were designated as controls and treated according to the plantation protocol. Capture rates of C. sordidus and M. hemipterus declined by >75 % over 10-12 months. In the banana growing region studied, corm damage was due primarily to C. sordidus, while only a minor amount of damage was attributable to M. hemipterus. Corm damage reduction in trapping plots was, thus, attributed primarily to C. sordidus trapping. In trapping plots, corm damage decreased by 61-64 % during the experiment. Banana bunch weights increased 23 % relative to control plots after 11-12 months of trapping. Fruit diameter did not vary between bunches harvested from trapping plots vs. control plots. Plant vigor, however, as determined by stem circumference at one meter above ground increased in plots with traps compared to control plots. Trapping for C. sordidus in two plantations of over 200 hectares each, reduced corm damage 62-86 % relative to pre-trapping levels. Insecticide control measures in place when the experiment commenced resulted in about 20-30 % corm damage, while use of pheromone trapping to manage C. sordidus lowered corm damage to 10 % or less. It is estimated that the increase in value of increased yield obtained in this trial (23 %) is about $4,240 USD per year per hectare, while the cost of pheromone trapping is approximately$185 USD per year per hectare. The trapping program becomes revenue neutral if bunch weights increase by an average of 1 % per year of trapping. Approximately 10 % of all plantation area in Costa Rica use the pheromone trapping system described here. The system also is used in Martinique
12. Aggregation behavior of cholic acid derivatives in organic solvents and in water
NARCIS (Netherlands)
Willemen, H.M.
2002-01-01
In this thesis various cholic acid derivatives are reported that display aggregation in water or in organic solvents. Spontaneous aggregation of single molecules into larger, ordered structures occurs at the borderline of solubility. Amphiphilic compounds, or surfactants, which possess a
13. HSF-1 is involved in regulation of ascaroside pheromone biosynthesis by heat stress in Caenorhabditis elegans.
Science.gov (United States)
Joo, Hyoe-Jin; Park, Saeram; Kim, Kwang-Youl; Kim, Mun-Young; Kim, Heekyeong; Park, Donha; Paik, Young-Ki
2016-03-15
The nematode worm Caenorhabditis elegans survives by adapting to environmental stresses such as temperature extremes by increasing the concentrations of ascaroside pheromones, termed ascarosides or daumones, which signal early C. elegans larvae to enter a non-aging dauer state for long-term survival. It is well known that production of ascarosides is stimulated by heat stress, resulting in enhanced dauer formation by which worms can adapt to environmental insults. However, the molecular mechanism by which ascaroside pheromone biosynthesis is stimulated by heat stress remains largely unknown. In the present study, we show that the heat-shock transcription factor HSF-1 can mediate enhanced ascaroside pheromone biosynthesis in response to heat stress by activating the peroxisomal fatty acid β-oxidation genes in C. elegans. To explore the potential molecular mechanisms, we examined the four major genes involved in the ascaroside biosynthesis pathway and then quantified the changes in both the expression of these genes and ascaroside production under heat-stress conditions. The transcriptional activation of ascaroside pheromone biosynthesis genes by HSF-1 was quite notable, which is not only supported by chromatin immunoprecipitation assays, but also accompanied by the enhanced production of chemically detectable major ascarosides (e.g. daumones 1 and 3). Consequently, the dauer formation rate was significantly increased by the ascaroside pheromone extracts from N2 wild-type but not from hsf-1(sy441) mutant animals grown under heat-stress conditions. Hence heat-stress-enhanced ascaroside production appears to be mediated at least in part by HSF-1, which seems to be important in adaptation strategies for coping with heat stress in this nematode. © 2016 Authors; published by Portland Press Limited.
14. COMPARING THE EFFECTIVENESS RATIOS OF PHEROMONE LURES OF IPSOWIT® ,IPSTYP®, AND TYPOSAN® AGAINST IPS TYPOGRAPHUS (L. (COL.: SCOLYTIDAE
Directory of Open Access Journals (Sweden)
Temel Göktürk
2005-04-01
Full Text Available In this study, effectiveness ratios of Ipsowit®, Ipstyp®, and Typosan® pheromone lures were compared. One research area within the pure spruce forests of Ardanuç-Karanlıkmeşe in Artvin Province of Turkey was selected for this study. A total of 30 pheromone traps (with ten of each type of pheromone lures were placed in the area. The traps hunging in the third week of May in 2003 stayed for 45 days. All of them were checked four times in 45 days to count trapped insects. As a result, in the early weeks of the placement, there were more insects collected, followed by a gradual decrease in trapped insect number in the later weeks. Furthermore, there was no significant difference between Ipstyp® and Typosan® in number of trapped insects. Both pheromone lures were, however, much more effective than Ipsowit®That is why, instead of Ipsowit®, using Ipstyp® and/or Typosan® lures against the pest would be more economic and more effective.
15. Combined action of sex pheromone and wasp Apanteles gelechiidivoris in greenhouse Tomato crops
International Nuclear Information System (INIS)
Morales, Jessica; Munoz, Laura; Rodriguez, Daniel; Cantor, Fernando
2014-01-01
The Tomato budworm, Tuta absoluta, is considered main pest of Tomato crops. Control of this pest is performed with hemicals, although, there are other strategies such as biological and ethological control. In Colombia there is not precedent that combines both strategies: ethological control with sexual pheromone and biological control with Apanteles gelechiidivoris, for the control of this pest in Tomato crops. In this work four different treatments under greenhouse conditions were evaluated including biological control with A. gelechiidivoris, ethological control with sexual pheromone traps, and combined action of both controls and traditional control (chemicals). The experiments aimed to developing a control strategy to reduce populations of T. absoluta. This was done sampling a plant every to 2 meters. From each plant a sample composed by one leaf by stratum was taken and the variables number of total larvae of third instar and parasited and number of captured adults for trap. The maximum parasitism in the population of susceptible larvae was 86.38 % and for total population of larvae was 68.75 %. The combined action of pheromone traps and A. gelechiidivoris presented a greater efficiency and permanence on the control of larvae of T. absoluta.
16. Behavior of Pectinophora gossypiella (gelechiidae) (pink bollworm) males monitored with pheromone trap in cotton
International Nuclear Information System (INIS)
Pontes de Melo, Elmo; Degrande, Paulo Eduardo; Aveiro Cessa, Raphael Maia; De Lima Junior, Izidro dos Santos; Barros, Ricardo; Fernandes Nogueira, Rodrigo
2012-01-01
The objective of the present study was to evaluate the behavior of p. gossypiella males captured with pheromone-baited traps in cotton field. Three experiments were done during the 2001-02 and 2002-03 growing seasons using the delta opal cotton cultivar. The first experiment was related to the insect population captured during the crop cycle by of two commercially available delta type traps, the second experiment was conducted to evaluate the efficiency of traps in capturing p. gossypiella males and, the third experiment assessed the nocturnal circadian rhythm. It was realized a descriptive analysis of the data collected to first and third experiment. Used in this second experiment consisted of comparing randomly selected groups and the means were compared by t-test, the significance level was set at 5 %, and, the canonical correlation analysis was performed. The delta pheromone trap was more efficient in capturing p. gossypiella than was the PET pheromone trap. Nocturnal activity peaks were found to be related with the time of year and it occurs between 11:00 p.m. and 2:00 a.m.
17. Computational Selection of Inhibitors of A-beta Aggregation and Neuronal Toxicity
Science.gov (United States)
Chen, Deliang; Martin, Zane S.; Soto, Claudio; Schein, Catherine H.
2009-01-01
Alzheimer’s Disease (AD) is characterized by the cerebral accumulation of misfolded and aggregated amyloid-β protein (Aβ). Disease symptoms can be alleviated, in vitro and in vivo, by “β-sheet breaker” pentapeptides that reduce plaque volume. However the peptide nature of these compounds, made them biologically unstable and unable to penetrate membranes with high efficiency. The main goal of this study was to use computational methods to identify small molecule mimetics with better drug-like properties. For this purpose, the docked conformations of the active peptides were used to identify compounds with similar activities. A series of related β-sheet breaker peptides were docked to solid state NMR structures of a fibrillar form of Aβ. The lowest energy conformations of the active peptides were used to design three dimensional (3D)-pharmacophores, suitable for screening the NCI database with Unity. Small molecular weight compounds with physicochemical features in a conformation similar to the active peptides were selected, ranked by docking solubility parameters. Of 16 diverse compounds selected for experimental screening, 2 prevented and reversed Aβ aggregation at 2–3 μM concentration, as measured by Thioflavin T (ThT) fluorescence and ELISA assays. They also prevented the toxic effects of aggregated Aβ on neuroblastoma cells. Their low molecular weight and aqueous solubility makes them promising lead compounds for treating AD. PMID:19540126
18. Indium mediated isoprenylation of carbonyl compounds with 2-bromomethyl-1,3-butadiene: a short synthesis of (±)-ipsenol
OpenAIRE
Ceschi Marco A.; Petzhold Cesar; Schenato Rossana A.
2003-01-01
Isoprenylation of aldehydes and ketones was directly performed by selective indium insertion on a mixture of 2-bromomethyl-1,3-butadiene and its vinylic isomers in good yields. A short synthesis of (±)-ipsenol, an aggregation pheromone of the Ips paraconfusus bark beetle, demonstrates the utility of this method in organic synthesis. A isoprenilação de aldeídos e cetonas foi realizada através da inserção seletiva de índio sobre uma mistura de 2-bromometil-1,3-butadieno e seus isômeros viníl...
19. De novo analysis of the Adelphocoris suturalis Jakovlev metathoracic scent glands transcriptome and expression patterns of pheromone biosynthesis-related genes.
Science.gov (United States)
Luo, Jing; Liu, Xiangyang; Liu, Lang; Zhang, Poyao; Chen, Longjia; Gao, Qiao; Ma, Weihua; Chen, Lizhen; Lei, Chaoliang
2014-11-10
Adelphocoris suturalis Jakovlev is a major cotton pest in Southern China. Metathoracic scent glands (MTGs) produced pheromones that play an important role in survival and population propagation of this species, and also show great potential for pest control. Up to the present, there is little information that underlined the molecular basis of the pheromone biosynthesis of this bug. It is essential to clarify genes involved in the production of pheromone components, and also in the regulation of the variation of the blend ratio. We sequenced the transcriptome of metathoracic scent glands (MTGs) of A. suturalis. A total of 52 million 91-bp-long reads were obtained and assembled into 70,296 unigenes with a mean length of 691bp. Of these unigenes, a total of 26,744 (38%) unigenes showed significant similarity to known proteins in the NCBI database (E-valuepheromone biosynthesis were selected, and the gene expression patterns were verified by qRT-PCR. The qRT-PCR results indicated that Asdelta9-DES, AsFAR, AsAOX, Ascarboxylesterase, AsNT-ES and AsATFs have a higher expression level in the period when female A. suturalis release sex pheromones. These data constitutes the first transcriptomic analysis exploring the repertoire of genes expressed in insect MTGs. We identified a large number of potential pheromone biosynthetic pathway genes. In this context, our study provides an invaluable resource for future exploration of molecular mechanisms of pheromone biosynthesis in A. suturalis, as well as other hemipteran species. Copyright © 2014 Elsevier B.V. All rights reserved.
20. Asymmetric Total Synthesis of Four Stereoisomers of the Sex Pheromone of the Western Corn Rootworm
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Zhi-Feng Sun
2018-03-01
Full Text Available A convergent synthesis of four stereoisomers of the sex pheromone of the western corn rootworm (8-methyldecan-2-yl propionate, 1 from commercially available chiral starting materials is reported. The key step was Julia–Kocienski olefination between chiral BT-sulfone and chiral aldehyde. This synthetic route provided the four stereoisomers of 1 in 24–29% total yield via a six-step sequence. The simple scale-up strategy provides a new way to achieve the asymmetric synthesis of the sex pheromone.
1. Stylopsal: The First Identified Female-produced Sex Pheromone of Strepsiptera
Czech Academy of Sciences Publication Activity Database
Cvačka, Josef; Jiroš, Pavel; Kalinová, Blanka; Straka, J.; Černá, K.; Šebesta, Petr; Tomčala, Aleš; Vašíčková, Soňa; Jahn, Ullrich; Šobotník, Jan
2012-01-01
Roč. 38, č. 12 (2012), s. 1483-1491 ISSN 0098-0331 R&D Projects: GA ČR GAP506/10/1466 Institutional support: RVO:61388963 Keywords : strepsiptera * stylops * sex pheromone * aldehyde * trimethyldodecanal * fat body Subject RIV: CC - Organic Chemistry Impact factor: 2.462, year: 2012
2. Trail pheromone of the leaf-cutting ant,Acromyrmex octospinosus (Reich), (Formicidae: Myrmicinae).
Science.gov (United States)
Cross, J H; West, J R; Silverstein, R M; Jutsum, A R; Cherrett, J M
1982-08-01
The most active component of the trail pheromone of the leafcutting ant,Acromyrmex octospinosus, is methyl 4-methylpyrrole-2-carboxylate (I). Two pyrazine isomers (II) and (III) are present but inactive.
3. Darcin: a male pheromone that stimulates female memory and sexual attraction to an individual male's odour
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McLean Lynn
2010-06-01
Full Text Available Abstract Background Among invertebrates, specific pheromones elicit inherent (fixed behavioural responses to coordinate social behaviours such as sexual recognition and attraction. By contrast, the much more complex social odours of mammals provide a broad range of information about the individual owner and stimulate individual-specific responses that are modulated by learning. How do mammals use such odours to coordinate important social interactions such as sexual attraction while allowing for individual-specific choice? We hypothesized that male mouse urine contains a specific pheromonal component that invokes inherent sexual attraction to the scent and which also stimulates female memory and conditions sexual attraction to the airborne odours of an individual scent owner associated with this pheromone. Results Using wild-stock house mice to ensure natural responses that generalize across individual genomes, we identify a single atypical male-specific major urinary protein (MUP of mass 18893Da that invokes a female's inherent sexual attraction to male compared to female urinary scent. Attraction to this protein pheromone, which we named darcin, was as strong as the attraction to intact male urine. Importantly, contact with darcin also stimulated a strong learned attraction to the associated airborne urinary odour of an individual male, such that, subsequently, females were attracted to the airborne scent of that specific individual but not to that of other males. Conclusions This involatile protein is a mammalian male sex pheromone that stimulates a flexible response to individual-specific odours through associative learning and memory, allowing female sexual attraction to be inherent but selective towards particular males. This 'darcin effect' offers a new system to investigate the neural basis of individual-specific memories in the brain and give new insights into the regulation of behaviour in complex social mammals. See associated
4. Darcin: a male pheromone that stimulates female memory and sexual attraction to an individual male's odour.
Science.gov (United States)
Roberts, Sarah A; Simpson, Deborah M; Armstrong, Stuart D; Davidson, Amanda J; Robertson, Duncan H; McLean, Lynn; Beynon, Robert J; Hurst, Jane L
2010-06-03
Among invertebrates, specific pheromones elicit inherent (fixed) behavioural responses to coordinate social behaviours such as sexual recognition and attraction. By contrast, the much more complex social odours of mammals provide a broad range of information about the individual owner and stimulate individual-specific responses that are modulated by learning. How do mammals use such odours to coordinate important social interactions such as sexual attraction while allowing for individual-specific choice? We hypothesized that male mouse urine contains a specific pheromonal component that invokes inherent sexual attraction to the scent and which also stimulates female memory and conditions sexual attraction to the airborne odours of an individual scent owner associated with this pheromone. Using wild-stock house mice to ensure natural responses that generalize across individual genomes, we identify a single atypical male-specific major urinary protein (MUP) of mass 18893Da that invokes a female's inherent sexual attraction to male compared to female urinary scent. Attraction to this protein pheromone, which we named darcin, was as strong as the attraction to intact male urine. Importantly, contact with darcin also stimulated a strong learned attraction to the associated airborne urinary odour of an individual male, such that, subsequently, females were attracted to the airborne scent of that specific individual but not to that of other males. This involatile protein is a mammalian male sex pheromone that stimulates a flexible response to individual-specific odours through associative learning and memory, allowing female sexual attraction to be inherent but selective towards particular males. This 'darcin effect' offers a new system to investigate the neural basis of individual-specific memories in the brain and give new insights into the regulation of behaviour in complex social mammals.See associated Commentary http://www.biomedcentral.com/1741-7007/8/71.
5. Synthetic sex pheromone in a long-lasting lure attracts the visceral leishmaniasis vector, Lutzomyia longipalpis, for up to 12 weeks in Brazil.
Directory of Open Access Journals (Sweden)
Daniel P Bray
2014-03-01
Full Text Available Current control methodologies have not prevented the spread of visceral leishmaniasis (VL across Brazil. Here, we describe the development of a new tool for controlling the sand fly vector of the disease: a long-lasting lure, which releases a synthetic male sex pheromone, attractive to both sexes of Lutzomyia longipalpis. This device could be used to improve the effectiveness of residual insecticide spraying as a means of sand fly control, attracting L. longipalpis to insecticide-treated animal houses, where they could be killed in potentially large numbers over a number of weeks. Different lure designs releasing the synthetic pheromone (±-9-methylgermacrene-B (CAS 183158-38-5 were field-tested in Araçatuba, São Paulo (SP. Experiments compared numbers of sand flies caught overnight in experimental chicken sheds with pheromone lures, to numbers caught in control sheds without pheromone. Prototype lures, designed to last one night, were first used to confirm the attractiveness of the pheromone in SP, and shown to attract significantly more flies to test sheds than controls. Longer-lasting lures were tested when new, and at fortnightly intervals. Lures loaded with 1 mg of pheromone did not attract sand flies for more than two weeks. However, lures loaded with 10 mg of pheromone, with a releasing surface of 15 cm2 or 7.5 cm2, attracted female L. longipalpis for up to ten weeks, and males for up to twelve weeks. Approximately five times more sand flies were caught with 7.5 cm2 10 mg lures when first used than occurred naturally in non-experimental chicken resting sites. These results demonstrate that these lures are suitably long-lasting and attractive for use in sand fly control programmes in SP. To our knowledge, this is the first sex pheromone-based technology targeting an insect vector of a neglected human disease. Further studies should explore the general applicability of this approach for combating other insect-borne diseases.
6. Aggregation in the tick Ixodes ricinus (Acari: Ixodidae): use and reuse of questing vantage points.
Science.gov (United States)
Healy, John A E; Bourke, Patrick
2008-03-01
Ongoing work in oak woods in Killarney National Park in southwestern Ireland is focusing on the factors influencing the fine-scale aggregated distribution of Ixodes ricinus L. (Acari: Ixodidae) on the ground. The extent of reuse of stems of vegetation as questing points by adult ticks was determined by paint-marking stems on which ticks were found, counting and removing these ticks, and subsequently reexamining the same stems for ticks on two further occasions. Overall, an estimated 2,967 stems in 123 separate rush plants (Juncus effusus L.) were examined. Statistical analysis of the data demonstrated a highly significant reoccupancy by ticks of stems previously and recently used. Furthermore, it is shown that the extent of stem reuse by ticks is significantly and positively correlated with the numbers of ticks originally observed on those stems. Although other factors may be involved in generating clumping of ticks, the results are compatible with the proposition that aggregation of I. ricinus on the ground is pheromone-mediated. The findings are discussed in relation to what is known about the powers of lateral movement of I. ricinus on the ground and the possible implications for the performance of tick traps.
7. Symmetry breaking on density in escaping ants: experiment and alarm pheromone model.
Directory of Open Access Journals (Sweden)
Geng Li
Full Text Available The symmetry breaking observed in nature is fascinating. This symmetry breaking is observed in both human crowds and ant colonies. In such cases, when escaping from a closed space with two symmetrically located exits, one exit is used more often than the other. Group size and density have been reported as having no significant impact on symmetry breaking, and the alignment rule has been used to model symmetry breaking. Density usually plays important roles in collective behavior. However, density is not well-studied in symmetry breaking, which forms the major basis of this paper. The experiment described in this paper on an ant colony displays an increase then decrease of symmetry breaking versus ant density. This result suggests that a Vicsek-like model with an alignment rule may not be the correct model for escaping ants. Based on biological facts that ants use pheromones to communicate, rather than seeing how other individuals move, we propose a simple yet effective alarm pheromone model. The model results agree well with the experimental outcomes. As a measure, this paper redefines symmetry breaking as the collective asymmetry by deducing the random fluctuations. This research indicates that ants deposit and respond to the alarm pheromone, and the accumulation of this biased information sharing leads to symmetry breaking, which suggests true fundamental rules of collective escape behavior in ants.
8. Sexual selection, sexual isolation and pheromones in Drosophila melanogaster strains after long-term maintaining on different diets.
Science.gov (United States)
Trajković, Jelena; Miličić, Dragana; Savić, Tatjana; Pavković-Lučić, Sofija
2017-07-01
Evolution of reproductive isolation may be a consequence of a variety of signals used in courtship and mate preferences. Pheromones play an important role in both sexual selection and sexual isolation. The abundance of pheromones in Drosophila melanogaster may depend on different environmental factors, including diet. The aim of this study was to ascertain to which degree principal pheromones affect sexual selection in D. melanogaster. We used D. melanogaster strains reared for 14 years on four substrates: standard cornmeal substrate and those containing tomato, banana and carrot. We have previously determined that long-term maintaining of these dietary strains resulted in differences in their cuticular hydrocarbons profile (CHs). In this work, we have tested the level of sexual selection and sexual isolation between aforementioned strains. We found that the high levels of cis-vaccenyl acetate, 7-pentacosene and 7,11-nonacosadiene in the strain reared on a substrate containing carrot affected the individual attractiveness and influenced sexual isolation between flies of this strain and flies reared on a substrate containing banana. Based on these results, long-term different diets, may contribute, to sexual behaviour of D. melanogaster via the effects of principal pheromones. Copyright © 2017 Elsevier B.V. All rights reserved.
9. Changes of sex pheromone communication systems associated with tebufenozide and abamectin resistance in diamondback moth, Plutella xylostella (L.).
Science.gov (United States)
Xu, Zhen; Cao, Guang-Chun; Dong, Shuang-Lin
2010-05-01
Many insect pests have evolved resistance to insecticides. Along with this evolution, the sex pheromone communication system of insects also may change, and subsequently reproductive isolation may occur between resistant and susceptible populations. In this study of the diamondback moth, we found that resistant females (especially Abamectin resistant females) produced less sex pheromone and displayed a lower level of calling behavior. Resistant males showed higher EAG responsiveness to the sex pheromone mixture of females, and responded to a broader range of ratios between the two major components compared to the responses of susceptible moths. In addition, wind tunnel experiments indicated that changes associated with insecticide resistance in the Abamectin resistant strain (Aba-R) significantly reduced female attractiveness to susceptible males. Furthermore, mating choice experiments confirmed that non-random mating occurred between the two different strains. Aba-R females with an abnormal pheromone production and blend ratio exhibited significantly lower mating percentages with males from either their own strain or other strains, which corroborates the results obtained by the wind tunnel experiments. The implications of this non-random mating for insect speciation and insecticide resistance management are discussed.
10. Enhanced attraction of Plutella xylostella (Lepidoptera: Plutellidae) to pheromone-baited traps with the addition of green leaf volatiles.
Science.gov (United States)
Li, Pengyan; Zhu, Junwei; Qin, Yuchuan
2012-08-01
Diamondback moth, Plutella xylostella (L.) (Lepidoptera: Plutellidae), is one of the most serious pests of Brassicaceae crops worldwide. Electrophysiological and behavioral responses of P. xylostella to green leaf volatiles (GLVs) alone or together with its female sex pheromone were investigated in laboratory and field. GLVs 1-hexanol and (Z)-3-hexen-1-ol elicited strong electroantennographic responses from unmated male and female P. xylostella, whereas (Z)-3-hexenyl acetate only produced a relatively weak response. The behavioral responses of unmated moths to GLVs were further tested in Y-tube olfactometer experiments. (E)-2-Hexenal, (Z)-3-hexen-1-ol, and (Z)-3-hexenyl acetate induced attraction of males, reaching up to 50%, significantly higher than the response to the unbaited control arm. In field experiments conducted in 2008 and 2009, significantly more moths were captured in traps baited with synthetic sex pheromone with either (Z)-3-hexenyl acetate alone or a blend of (Z)-3-hexenyl acetate, (Z)-3-hexen-1-ol, and (E)-2-hexenal compared with sex pheromone alone and other blend mixtures. These results demonstrated that GLVs could be used to enhance the attraction of P. xylostella males to sex pheromone-baited traps.
11. Sexy Mouth Odour? Male Oral Gland Pheromone in the Grain Beetle Parasitoid Lariophagus distinguendus (Förster) (Hymenoptera: Pteromalidae).
Science.gov (United States)
König, Kerstin; Seeger, Lucy; Steidle, Johannes L M
2015-01-01
Throughout the animal kingdom, sexual pheromones are used for the attraction of mates and as courtship signals but also enable sexual isolation between species. In the parasitic wasp Lariophagus distinguendus, male courtship behaviour consisting of wing fanning, antennal stroking of the female antenna, and head nodding stimulates female receptivity leading to copulation. Recently L. distinguendus was reported to consist of two different lineages, which are sexually isolated because males fail to elicit receptivity in foreign females. It is unclear, however, which part of the courtship behaviour triggers female receptivity and therefore could be a mechanism causing sexual isolation. Here we show that in L. distinguendus a nonvolatile male oral pheromone is essential to release the female receptivity signal. In contrast, male wing fanning and antennal contact play a minor role. Additionally, the composition of the oral pheromone depends on the developmental host and females learn the composition upon emergence from the host substrate. These results will enable more detailed work on oral sexual pheromones to answer the question of how they are involved in the speciation process of L. distinguendus and other parasitoid species, for a better understanding of the huge biodiversity in this group.
12. Sexy Mouth Odour? Male Oral Gland Pheromone in the Grain Beetle Parasitoid Lariophagus distinguendus (Förster (Hymenoptera: Pteromalidae
Directory of Open Access Journals (Sweden)
Kerstin König
2015-01-01
Full Text Available Throughout the animal kingdom, sexual pheromones are used for the attraction of mates and as courtship signals but also enable sexual isolation between species. In the parasitic wasp Lariophagus distinguendus, male courtship behaviour consisting of wing fanning, antennal stroking of the female antenna, and head nodding stimulates female receptivity leading to copulation. Recently L. distinguendus was reported to consist of two different lineages, which are sexually isolated because males fail to elicit receptivity in foreign females. It is unclear, however, which part of the courtship behaviour triggers female receptivity and therefore could be a mechanism causing sexual isolation. Here we show that in L. distinguendus a nonvolatile male oral pheromone is essential to release the female receptivity signal. In contrast, male wing fanning and antennal contact play a minor role. Additionally, the composition of the oral pheromone depends on the developmental host and females learn the composition upon emergence from the host substrate. These results will enable more detailed work on oral sexual pheromones to answer the question of how they are involved in the speciation process of L. distinguendus and other parasitoid species, for a better understanding of the huge biodiversity in this group.
13. Light-induced aggregation of microbial exopolymeric substances.
Science.gov (United States)
Sun, Luni; Xu, Chen; Zhang, Saijin; Lin, Peng; Schwehr, Kathleen A; Quigg, Antonietta; Chiu, Meng-Hsuen; Chin, Wei-Chun; Santschi, Peter H
2017-08-01
14. A candidate pheromone receptor and two odorant receptors of the hawkmoth Manduca sexta.
Science.gov (United States)
Patch, Harland M; Velarde, Rodrigo A; Walden, Kimberly K O; Robertson, Hugh M
2009-05-01
In this study, we cloned and characterized three Manduca sexta odorant receptors (ORs). One receptor is a putative pheromone receptor expressed exclusively in a cell associated with male-specific type-I trichoid sensilla. We describe the results of real-time PCR (RT-PCR) and quantitative real-time PCR (qRT-PCR) experiments that show MsextaOR1 is expressed only in male antennae. In situ hybridization labels a single cell associated with type-1 trichoid sensilla, which houses two neurons that have been previously determined to respond to the major components of the pheromone blend. The second receptor, MsextaOR2, was discovered using degenerate primers designed to conserved motifs of a unique group ORs that share as much as 88% identity. Comparison of RT-PCR, qRT-PCR, and in situ hybridization results with those of ORs in the Drosophila melanogaster Or83b subfamily shows a strong sequence and expression pattern similarity. The third receptor, MsextaOR3, was found by 5'-end sequencing of a normalized and subtracted cDNA library from male M. sexta antennae. RT-PCR and qRT-PCR show that this receptor is expressed only in male and female antennae. These are the first ORs, including a putative pheromone receptor, to be described from M. sexta.
15. Multiple functions of a multi-component mating pheromone in sea lamprey Petromyzon marinus
Science.gov (United States)
Johnson, N.S.; Yun, S.-S.; Buchinger, T.J.; Li, W.
2012-01-01
The role of the C24 sulphate in the mating pheromone component, 7α,12α,24-trihydroxy-5α-cholan-3-one 24-sulphate (3kPZS), to specifically induce upstream movement in ovulated female sea lampreys Petromyzon marinus was investigated. 7α,12α-dihydroxy-5α-cholan-3-one 24-oic acid (3kACA), a structurally similar bile acid released by spermiated males, but lacking the C24 sulphate ester, was tested in bioassays at concentrations between 10−11 and 10−14 molar (M). 3kACA did not induce upstream movement in females or additional reproductive behaviours. In contrast, spermiated male washings induced upstream movement, prolonged retention on a nest and induced an array of nesting behaviours. Differential extraction and elution by solid-phase extraction resins showed that components other than 3kPZS + 3kACA are necessary to retain females on nests and induce nest cleaning behaviours. All pheromone components, including components in addition to 3kPZS + 3kACA that retain females and induce nest cleaning behaviours were released from the anterior region of the males, as had been reported for 3kPZS. It is concluded that the sea lamprey male mating pheromone has multiple functions and is composed of multiple components.
16. The effect of queen pheromone status on Varroa mite removal from honey bee colonies with different grooming ability.
Science.gov (United States)
Bahreini, Rassol; Currie, Robert W
2015-07-01
The objective of this study was to assess the effects of honey bees (Apis mellifera L.) with different grooming ability and queen pheromone status on mortality rates of Varroa mites (Varroa destructor Anderson and Trueman), mite damage, and mortality rates of honey bees. Twenty-four small queenless colonies containing either stock selected for high rates of mite removal (n = 12) or unselected stock (n = 12) were maintained under constant darkness at 5 °C. Colonies were randomly assigned to be treated with one of three queen pheromone status treatments: (1) caged, mated queen, (2) a synthetic queen mandibular pheromone lure (QMP), or (3) queenless with no queen substitute. The results showed overall mite mortality rate was greater in stock selected for grooming than in unselected stock. There was a short term transitory increase in bee mortality rates in selected stock when compared to unselected stock. The presence of queen pheromone from either caged, mated queens or QMP enhanced mite removal from clusters of bees relative to queenless colonies over short periods of time and increased the variation in mite mortality over time relative to colonies without queen pheromone, but did not affect the proportion of damaged mites. The effects of source of bees on mite damage varied with time but damage to mites was not reliably related to mite mortality. In conclusion, this study showed differential mite removal of different stocks was possible under low temperature. Queen status should be considered when designing experiments using bioassays for grooming response.
17. Potential for the use of male pheromone components in female trapping: a progress report
International Nuclear Information System (INIS)
Howse, P.E.; Underwood, K.L.; Knapp, J.J.; Alemany Ferra, A.; Miranda, M.A.
1999-01-01
Experiments were conducted to determine if reducing the male population using TML traps and pheromone baited traps would enhance female Mediterranean fruit fly capture. Investigations were conducted in citrus plantations in Mallorca. In the first trial (0.36 ha, Son Coll Vey, Palma) Agrisense yellow delta traps were deployed on every third tree in adjacent rows. On each other tree, a TML bait was placed with an insecticide strip containing Dichlorvos. Thus, each of the delta traps was surrounded by a hexagon of TML + insecticide baited trees. The rationale of this experiment was to remove males from the vicinity of pheromone-baited traps and thereby increase the apparency of the female lure. Before the trial, male catches averaged 4.1 per day in TML traps. During the trial, this was reduced to approximately 0.6 males/trap/day. The traps with pheromone (pyrazines in various combinations and ratios) caught around 0.05 females/trap/day. The pheromone traps remained female selective, with a negligible male catch, similar to that in unbaited traps. The most likely cause for the very low female catch may be that insufficient males were removed by the lure and kill devices. In the second trial (0.67 ha, Inca, Mallorca) the proprietor had deployed 83 traps, baited with TML and insecticide, for 18 days prior to the placement of five treatments with six replicates. The delta traps were placed on every third tree, with replicates every third row. The female catch showed a progressive enhancement over a period of 6 weeks, reaching a level about six times that of males in TML traps. (author)
18. How to make a sexy snake: estrogen activation of female sex pheromone in male red-sided garter snakes.
Science.gov (United States)
Parker, M Rockwell; Mason, Robert T
2012-03-01
Vertebrates indicate their genetic sex to conspecifics using secondary sexual signals, and signal expression is often activated by sex hormones. Among vertebrate signaling modalities, the least is known about how hormones influence chemical signaling. Our study species, the red-sided garter snake (Thamnophis sirtalis parietalis), is a model vertebrate for studying hormonal control of chemical signals because males completely rely on the female sex pheromone to identify potential mates among thousands of individuals. How sex hormones can influence the expression of this crucial sexual signal is largely unknown. We created two groups of experimental males for the first experiment: Sham (blank implants) and E2 (17β-estradiol implants). E2 males were vigorously courted by wild males in outdoor bioassays, and in a Y-maze E2 pheromone trails were chosen by wild males over those of small females and were indistinguishable from large female trails. Biochemically, the E2 pheromone blend was similar to that of large females, and it differed significantly from Shams. For the second experiment, we implanted males with 17β-estradiol in 2007 but removed the implants the following year (2008; Removal). That same year, we implanted a new group of males with estrogen implants (Implant). Removal males were courted by wild males in 2008 (implant intact) but not in 2009 (removed). Total pheromone quantity and quality increased following estrogen treatment, and estrogen removal re-established male-typical pheromone blends. Thus, we have shown that estrogen activates the production of female pheromone in adult red-sided garter snakes. This is the first known study to quantify both behavioral and biochemical responses in chemical signaling following sex steroid treatment of reptiles in the activation/organization context. We propose that the homogametic sex (ZZ, male) may possess the same targets for activation of sexual signal production, and the absence of the activator (17
19. Change in sex pheromone expression by nutritional shift in male cockroaches
DEFF Research Database (Denmark)
Jensen, Kim; Shearman, Melanie; Rapkin, James
2017-01-01
affected by dietary nutrient composition with higher values on carbohydrate-biased diet, and males had significantly higher and lower levels of consumption, lipid reserves, and sex pheromones when shifted to a carbohydrate-biased and a protein-biased diet, respectively, compared with males maintained...
20. Pheromone-induced priming of a defensive response in Western flower thrips
NARCIS (Netherlands)
de Bruijn, P.J.A.; Egas, M.; Janssen, A.; Sabelis, M.W.
2006-01-01
Abstract The Western flower thrips Frankliniella occidentalis produces conspicuous anal droplets that function as a direct defense against various predators. These droplets also function in pheromonal communication in that they contain a mixture of decyl acetate and dodecyl acetate, which acts as an
1. Brood pheromone effects on colony protein supplement consumption and growth in the honey bee (Hymenoptera: Apidae) in a subtropical winter climate.
Science.gov (United States)
Pankiw, Tanya; Sagili, Ramesh R; Metz, Bradley N
2008-12-01
Fatty acid esters extractable from the surface of honey bee, Apis mellifera L. (Hymenoptera: Apidae), larvae, called brood pheromone, significantly increase rate of colony growth in the spring and summer when flowering plant pollen is available in the foraging environment. Increased colony growth rate occurs as a consequence of increased pollen intake through mechanisms such as increasing number of pollen foragers and pollen load weights returned. Here, we tested the hypothesis that addition of brood pheromone during the winter pollen dearth period of a humid subtropical climate increases rate of colony growth in colonies provisioned with a protein supplement. Experiments were conducted in late winter (9 February-9 March 2004) and mid-winter (19 January-8 February 2005). In both years, increased brood area, number of bees, and amount of protein supplement consumption were significantly greater in colonies receiving daily treatments of brood pheromone versus control colonies. Amount of extractable protein from hypopharyngeal glands measured in 2005 was significantly greater in bees from pheromone-treated colonies. These results suggest that brood pheromone may be used as a tool to stimulate colony growth in the southern subtropical areas of the United States where the package bee industry is centered and a large proportion of migratory colonies are overwintered.
2. Expression of the mevalonate pathway enzymes in the Lutzomyia longipalpis (Diptera: Psychodidae) sex pheromone gland demonstrated by an integrated proteomic approach.
Science.gov (United States)
González-Caballero, Natalia; Rodríguez-Vega, Andrés; Dias-Lopes, Geovane; Valenzuela, Jesus G; Ribeiro, Jose M C; Carvalho, Paulo Costa; Valente, Richard H; Brazil, Reginaldo P; Cuervo, Patricia
2014-01-16
In Latin America, Lutzomyia longipalpis is the main vector of the protozoan parasite Leishmania infantum, which is the causal agent of American Visceral Leishmaniasis. This insect uses male-produced pheromones for mate recognition. Elucidation of pheromone biogenesis or its regulation may enable molecular strategies for mating disruption and, consequently, the vector's population management. Motivated by our recent results of the transcriptomic characterization of the L. longipalpis pheromone gland, we performed a proteomic analysis of this tissue combining SDS-PAGE, and mass spectrometry followed by an integrative data analysis. Considering that annotated genome sequences of this sand fly are not available, we designed an alternative workflow searching MS/MS data against two customized databases using three search engines: Mascot, OMSSA and ProLuCID. A total of 542 proteins were confidently characterized, 445 of them using a Uniref100-insect protein database, and 97 using a transcript translated database. In addition, use of PEAKS for de novo peptide sequencing of MS/MS data confirmed ~90% identifications made with the combination of the three search engines. Our results include the identification of six of the seven enzymes of the mevalonate-pathway, plus the enzymes involved in sesquiterpenoid biosynthesis, all of which are proposed to be involved in pheromone production in L. longipalpis. L. longipalpis is the main vector of the protozoan parasite L. infantum, which is the causal agent of American Visceral Leishmaniasis. One of the control measures of such disease is focused on vector population control. As this insect uses male-produced pheromones for mate recognition, the elucidation of pheromone biogenesis or its regulating process may enable molecular strategies for mating disruption and, consequently, this vector's population management. On this regard, in this manuscript we report expression evidence, at the protein level, of several molecules potentially
3. New Sesquiterpenoids and Anti-Platelet Aggregation Constituents from the Rhizomes of Curcuma zedoaria.
Science.gov (United States)
Chen, Jih-Jung; Tsai, Tung-Han; Liao, Hsiang-Ruei; Chen, Li-Chai; Kuo, Yueh-Hsiung; Sung, Ping-Jyun; Chen, Chun-Lin; Wei, Chun-Sheng
2016-10-17
Two new sesquiterpenoids-13-hydroxycurzerenone ( 1 ) and 1-oxocurzerenone ( 2 )-have been isolated from the rhizomes of Curcuma zedoaria , together with 13 known compounds ( 3 - 15 ). The structures of two new compounds were determined through spectroscopic and MS analyses. Among the isolated compounds, 13-hydroxycurzerenone ( 1 ), 1-oxocurzerenone ( 2 ), curzerenone ( 3 ), germacrone ( 4 ), curcolone ( 5 ), procurcumenol ( 6 ), ermanin ( 7 ), curcumin ( 8 ), and a mixture of stigmast-4-en-3,6-dione ( 12 ) and stigmasta-4,22-dien-3,6-dione ( 13 ) exhibited inhibition (with inhibition % in the range of 21.28%-67.58%) against collagen-induced platelet aggregation at 100 μM. Compounds 1 , 5 , 7 , 8 , and the mixture of 12 and 13 inhibited arachidonic acid (AA)-induced platelet aggregation at 100 μM with inhibition % in the range of 23.44%-95.36%.
4. Role of nitric oxide in pheromone-mediated intraspecific communication in mice.
Science.gov (United States)
Agustín-Pavón, Carmen; Martínez-Ricós, Joana; Martínez-García, Fernando; Lanuza, Enrique
2009-12-07
Nitric oxide is known to take part in the control of sexual and agonistic behaviours. This is usually attributed to its role in neural transmission in the hypothalamus and other structures of the limbic system. However, socio-sexual behaviours in rodents are mainly directed by chemical signals detected by the vomeronasal system, and nitric oxide is abundant in key structures along the vomeronasal pathway. Thus, here we check whether pharmacological treatments interfering with nitrergic transmission could affect socio-sexual behaviour by impairing the processing of chemical signals. Treatment with an inhibitor of nitric oxide synthesis (Nomega-Nitro-l-arginine methyl ester hydrochloride, L-NAME, 100mg/kg) blocks the innate preference displayed by female mice for sexual pheromones contained in male-soiled bedding, with a lower dose of the drug (50mg/kg) having no effect. Animals treated with the high dose of L-NAME show no reduction of olfactory discrimination of male urine in a habituation-dishabituation test, thus suggesting that the effect of the drug on the preference for male pheromones is not due to an inability to detect male urine. Alternatively, it may result from an alteration in processing the reinforcing value of pheromones as sexual signals. These results add a new piece of evidence to our understanding of the neurochemistry of intraspecific chemical communication in rodents, and suggest that the role of nitric oxide in socio-sexual behaviours should be re-evaluated taking into account the involvement of this neuromodulator in the processing of chemical signals.
5. Trail pheromone of the Argentine ant, Linepithema humile (Mayr (Hymenoptera: Formicidae.
Directory of Open Access Journals (Sweden)
Dong-Hwan Choe
Full Text Available The Argentine ant (Linepithema humile is recognized as one of the world's most damaging invasive species. One reason for the ecological dominance of introduced Argentine ant populations is their ability to dominate food and habitat resources through the rapid mobilization and recruitment of thousands of workers. More than 30 years ago, studies showed that (Z-9-hexadecenal strongly attracted Argentine ant workers in a multi-choice olfactometer, suggesting that (Z-9-hexadecenal might be the trail pheromone, or a component of a trail pheromone mixture. Since then, numerous studies have considered (Z-9-hexadecenal as the key component of the Argentine ant trails. Here, we report the first chemical analyses of the trails laid by living Argentine ants and find that (Z-9-hexadecenal is not present in a detectible quantity. Instead, two iridoids, dolichodial and iridomyrmecin, appear to be the primary chemical constituents of the trails. Laboratory choice tests confirmed that Argentine ants were attracted to artificial trails comprised of these two chemicals significantly more often than control trails. Although (Z-9-hexadecenal was not detected in natural trails, supplementation of artificial dolichodial+iridomyrmecin trails with an extremely low concentraion of (Z-9-hexadecenal did increase the efficacy of the trail-following behavior. In stark contrast with previous dogma, our study suggests that dolichodial and iridomyrmecin are major components of the Argentine ant trail pheromone. (Z-9-hexadecenal may act in an additive manner with these iridoids, but it does not occur in detectable quantities in Argentine ant recruitment trails.
6. Continued pheromone release by boll weevils (Coleoptera: curculionidae) following host removal
Science.gov (United States)
Pheromone traps are a key component of management and eradication programs directed against the boll weevil, Anthonomus grandis (Boheman), but trap data remain difficult to interpret because of the day-to-day variability in captures. Our prior observations suggested a substantial proportion of boll...
7. Manipulating Aggregation Behavior of the Uncharged Peptide Carbetocin
DEFF Research Database (Denmark)
Høgstedt, Ulrich B; Østergaard, Jesper; Weiss, Torsten
2018-01-01
Peptides are usually administered through subcutaneous injection. For low potency drugs, this may require high concentration formulations increasing the risk of peptide aggregation, especially for compounds without any intrinsic chargeable groups. Carbetocin was used as a model to study the behav...
8. Optimum timing of insecticide applications against diamondback moth Plutella xylostella in cole crops using threshold catches in sex pheromone traps.
Science.gov (United States)
Reddy, G V; Guerrero, A
2001-01-01
Field trials were conducted in cabbage (Brassica oleracea var capitata), cauliflower (B oleracea var botrytis) and knol khol (B oleracea gongylodes) crops at two different locations in Karnataka State (India) to optimize the timing of insecticide applications to control the diamondback moth, Plutella xylostella, using sex pheromone traps. Our results indicate that applications of cartap hydrochloride as insecticide during a 12-24 h period after the pheromone traps had caught on average 8, 12 and 16 males per trap per night in cabbage, cauliflower and knol khol, respectively, were significantly more effective than regular insecticide sprays at 7, 9, 12 or 15 days after transplantation. This was demonstrated by estimation of the mean number of eggs and larvae per plant, the percentage of holes produced, as well as the marketable yield of the three crops at each location. A good correlation between the immature stages, infestation level, the estimated crop yield and the number of moths caught in pheromone traps was also found, indicating the usefulness of pheromone-based monitoring traps to predict population densities of the pest.
9. Various Bee Pheromones Binding Affinity, Exclusive Chemosensillar Localization, and Key Amino Acid Sites Reveal the Distinctive Characteristics of Odorant-Binding Protein 11 in the Eastern Honey Bee, Apis cerana.
Science.gov (United States)
Song, Xin-Mi; Zhang, Lin-Ya; Fu, Xiao-Bin; Wu, Fan; Tan, Jing; Li, Hong-Liang
2018-01-01
Odorant-binding proteins (OBPs) are the critical elements responsible for binding and transporting odors and pheromones in the sensitive olfactory system in insects. Honey bees are representative social insects that have complex odorants and pheromone communication systems relative to solitary insects. Here, we first cloned and characterized OBP11 ( AcerOBP11 ), from the worker bees antennae of Eastern honey bee, Apis cerana . Based on sequence and phylogenetic analysis, most sequences homologous to AcerOBP11 belong to the typical OBPs family. The transcriptional expression profiles showed that AcerOBP11 was expressed throughout the developmental stages and highly specifically expressed in adult antennae. Using immunofluorescence localization, AcerOBP11 in worker bee's antennae was only localized in the sensilla basiconica (SB) near the fringe of each segment. Fluorescence ligand-binding assay showed that AcerOBP11 protein had strong binding affinity with the tested various bee pheromones components, including the main queen mandibular pheromones (QMPs), methyl p-hydroxybenzoate (HOB), and ( E )-9-oxo-2-decanoic acid (9-ODA), alarm pheromone (n-hexanol), and worker pheromone components. AcerOBP11 also had strong binding affinity to plant volatiles, such as 4-Allylveratrole. Based on the docking and site-directed mutagenesis, two key amino acid residues (Ile97 and Ile140) were involved in the binding of AcerOBP11 to various bee pheromones. Taken together, we identified that AcerOBP11 was localized in a single type of antennal chemosensilla and had complex ligand-binding properties, which confer the dual-role with the primary characteristics of sensing various bee pheromones and secondary characteristics of sensing general odorants. This study not only prompts the theoretical basis of OBPs-mediated bee pheromones recognition of honey bee, but also extends the understanding of differences in pheromone communication between social and solitary insects.
10. Various Bee Pheromones Binding Affinity, Exclusive Chemosensillar Localization, and Key Amino Acid Sites Reveal the Distinctive Characteristics of Odorant-Binding Protein 11 in the Eastern Honey Bee, Apis cerana
Directory of Open Access Journals (Sweden)
Xin-Mi Song
2018-04-01
Full Text Available Odorant-binding proteins (OBPs are the critical elements responsible for binding and transporting odors and pheromones in the sensitive olfactory system in insects. Honey bees are representative social insects that have complex odorants and pheromone communication systems relative to solitary insects. Here, we first cloned and characterized OBP11 (AcerOBP11, from the worker bees antennae of Eastern honey bee, Apis cerana. Based on sequence and phylogenetic analysis, most sequences homologous to AcerOBP11 belong to the typical OBPs family. The transcriptional expression profiles showed that AcerOBP11 was expressed throughout the developmental stages and highly specifically expressed in adult antennae. Using immunofluorescence localization, AcerOBP11 in worker bee's antennae was only localized in the sensilla basiconica (SB near the fringe of each segment. Fluorescence ligand-binding assay showed that AcerOBP11 protein had strong binding affinity with the tested various bee pheromones components, including the main queen mandibular pheromones (QMPs, methyl p-hydroxybenzoate (HOB, and (E-9-oxo-2-decanoic acid (9-ODA, alarm pheromone (n-hexanol, and worker pheromone components. AcerOBP11 also had strong binding affinity to plant volatiles, such as 4-Allylveratrole. Based on the docking and site-directed mutagenesis, two key amino acid residues (Ile97 and Ile140 were involved in the binding of AcerOBP11 to various bee pheromones. Taken together, we identified that AcerOBP11 was localized in a single type of antennal chemosensilla and had complex ligand-binding properties, which confer the dual-role with the primary characteristics of sensing various bee pheromones and secondary characteristics of sensing general odorants. This study not only prompts the theoretical basis of OBPs-mediated bee pheromones recognition of honey bee, but also extends the understanding of differences in pheromone communication between social and solitary insects.
11. Isolation, identification and field tests of the sex pheromone of the carambola fruit borer, Eucosma notanthes.
Science.gov (United States)
Hung, C C; Hwang, J S; Hung, M D; Yen, Y P; Hou, R F
2001-09-01
Two components, (Z)-8-dodecenyl acetate (Z8-12:Ac) and (Z)-8-dodecenol (Z8-12:OH), were isolated from sex pheromone glands of the carambola fruit borer, Eucosma notanthes, and were identified by GC, and GC-MS, chemical derivatization, and comparison of retention times. The ratio of the alcohol to acetate in the sex pheromone extracts was 2.7. However, synthetic mixtures (1 mg) in ratios ranging from 0.5 to 1.5 were more effective than other blends in trapping male moths in field tests.
12. Effect of surfactants on the aggregation of pyronin B and pyronin Y in aqueous solution
Energy Technology Data Exchange (ETDEWEB)
Arik, Mustafa; Meral, Kadem [Department of Chemistry, Faculty of Sciences, Atatuerk University, 25240 Erzurum (Turkey); Onganer, Yavuz, E-mail: yonganer@atauni.edu.t [Department of Chemistry, Faculty of Sciences, Atatuerk University, 25240 Erzurum (Turkey)
2009-06-15
Molecular dynamics of pyronin B (PyB) and pyronin Y (PyY) in aqueous solution containing different surfactants were investigated by using absorption and fluorescence spectroscopy techniques. First, the interactions of PyB and PyY with the negatively charged surfactant sodium dodecyl sulphate (SDS) were investigated in the below and above critical micelle concentration (cmc). The H-aggregate formation of the dye compounds was observed for below the cmc of SDS surfactant. The absorbance of H-aggregate absorption band of PyB and PyY decreased according to the aggregate-monomer equilibrium by increasing SDS surfactant concentration towards the cmc. Therefore, equilibrium constants of the aggregate formation and oscillator strengths of monomer and aggregate of the dye compounds were calculated from spectral studies. Moreover, aggregate formation dynamics was discussed in terms of thermodynamic functions by using temperature studies. The interactions of PyB and PyY with the positively charged hexadecyltrimethylammonium bromide (CTAB) and neutral Triton X-100 (TX-100) were also studied and it was observed that there was no aggregate formation on the absorption and fluorescence spectra for below and above the cmc.
13. Dynamical modeling of the moth pheromone-sensitive olfactory receptor neuron within its sensillar environment.
Directory of Open Access Journals (Sweden)
Yuqiao Gu
Full Text Available In insects, olfactory receptor neurons (ORNs, surrounded with auxiliary cells and protected by a cuticular wall, form small discrete sensory organs--the sensilla. The moth pheromone-sensitive sensillum is a well studied example of hair-like sensillum that is favorable to both experimental and modeling investigations. The model presented takes into account both the molecular processes of ORNs, i.e. the biochemical reactions and ionic currents giving rise to the receptor potential, and the cellular organization and compartmentalization of the organ represented by an electrical circuit. The number of isopotential compartments needed to describe the long dendrite bearing pheromone receptors was determined. The transduction parameters that must be modified when the number of compartments is increased were identified. This model reproduces the amplitude and time course of the experimentally recorded receptor potential. A first complete version of the model was analyzed in response to pheromone pulses of various strengths. It provided a quantitative description of the spatial and temporal evolution of the pheromone-dependent conductances, currents and potentials along the outer dendrite and served to determine the contribution of the various steps in the cascade to its global sensitivity. A second simplified version of the model, utilizing a single depolarizing conductance and leak conductances for repolarizing the ORN, was derived from the first version. It served to analyze the effects on the sensory properties of varying the electrical parameters and the size of the main sensillum parts. The consequences of the results obtained on the still uncertain mechanisms of olfactory transduction in moth ORNs--involvement or not of G-proteins, role of chloride and potassium currents--are discussed as well as the optimality of the sensillum organization, the dependence of biochemical parameters on the neuron spatial extension and the respective contributions
14. Anti-Platelet Aggregation and Vasorelaxing Effects of the Constituents of the Rhizomes of Zingiber officinale
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Tian-Shung Wu
2012-07-01
Full Text Available In the present study, the chemical investigation of the bioactive fractions of the rhizomes of Zingiber officinale has resulted in the identification of twenty-nine compounds including one new compound, O-methyldehydrogingerol (1. Some of the isolates were subjected into the evaluation of their antiplatelet aggregation and vasorelaxing bioactivities. Among the tested compounds, [6]-gingerol (13 and [6]-shogaol (17 exhibited potent anti-platelet aggregation bioactivity. In addition, [10]-gingerol (15 inhibited the Ca2+-dependent contractions in high K+ medium. According to the results in the present research, the bioactivity of ginger could be related to the anti-platelet aggregation and vasorelaxing mechanism.
15. Tracking of Fluid-Advected Odor Plumes: Strategies Inspired by Insect Orientation to Pheromone
National Research Council Canada - National Science Library
Li, Wei
2002-01-01
.... These strategies are inspired by the maneuvers of moths flying upwind along a pheromone plume. Although moth maneuvers are well documented, the mechanisms underlying sensory perception and navigation are not fully understood...
16. Healthy Adult Male Facial Skin Surface Lipid Pheromone p.o. to Treat Opioid Addiction
Science.gov (United States)
2018-03-20
Opioid Addiction; Opioid Abuse, Continuous Use; Opioid Use; Opioid-Related Disorders; Paternal Pheromone Deficiency; Opioid Dependence; Opioid Abuse; Opioid-use Disorder; Opioid Intoxication; Opioid Abuse, Episodic
17. Integration of pheromones and biological control for the management of cotton bollworms in Pakistan
International Nuclear Information System (INIS)
Ahmad, N.; Ashraf, M.; Hussain, T.; Fatima, B.
2002-01-01
The management of cotton bollworms in a semi-isolated area through the use of inundative releases of the egg parasitoid Trichogramma chilonis (Hymenoptera: Trichogrammatidae) in conjunction with pheromones suppressed populations of the pink and spotted bollworms to sub-economic levels. The parasitoid was more effective against pink bollworm than spotted bollworm. Applications of either pheromones or parasitoids by themselves were less effective when compared to the combined treatment. The level of parasitism in the cotton field was comparatively low in June and July but gradually increased during August and September. Maximum parasitism was recorded in November. Studies indicated that temperature affected the establishment of the parasitoid, and populations increased significantly when favourable conditions prevailed in the cotton field. (author)
18. Functional evolution of a multigene family: orthologous and paralogous pheromone receptor genes in the turnip moth, Agrotis segetum.
Directory of Open Access Journals (Sweden)
Dan-Dan Zhang
Full Text Available Lepidopteran pheromone receptors (PRs, for which orthologies are evident among closely related species, provide an intriguing example of gene family evolution in terms of how new functions may arise. However, only a limited number of PRs have been functionally characterized so far and thus evolutionary scenarios suffer from elements of speculation. In this study we investigated the turnip moth Agrotis segetum, in which female moths produce a mixture of chemically related pheromone components that elicit specific responses from receptor cells on male antennae. We cloned nine A. segetum PR genes and the Orco gene by degenerate primer based RT-PCR. The nine PR genes, named as AsegOR1 and AsegOR3-10, fall into four distinct orthologous clusters of known lepidopteran PRs, of which one contains six paralogues. The paralogues are under relaxed selective pressure, contrasting with the purifying selection on other clusters. We identified the receptors AsegOR9, AsegOR4 and AsegOR5, specific for the respective homologous pheromone components (Z-5-decenyl, (Z-7-dodecenyl and (Z-9-tetradecenyl acetates, by two-electrode voltage clamp recording from Xenopus laevis oocytes co-expressing Orco and each PR candidate. These receptors occur in three different orthologous clusters. We also found that the six paralogues with high sequence similarity vary dramatically in ligand selectivity and sensitivity. Different from AsegOR9, AsegOR6 showed a relatively large response to the behavioural antagonist (Z-5-decenol, and a small response to (Z-5-decenyl acetate. AsegOR1 was broadly tuned, but most responsive to (Z-5-decenyl acetate, (Z-7-dodecenyl acetate and the behavioural antagonist (Z-8-dodecenyl acetate. AsegOR8 and AsegOR7, which differ from AsegOR6 and AsegOR1 by 7 and 10 aa respectively, showed much lower sensitivities. AsegOR10 showed only small responses to all the tested compounds. These results suggest that new receptors arise through gene duplication, and
19. Synthesis of insect pheromones belonging to the group of (Z)-trisubstituted alkenes
International Nuclear Information System (INIS)
Grigorieva, Natalia Ya; Tsiklauri, Paata G
2000-01-01
Stereo- and regiocontrolled methods for the construction of a (Z)-trisubstituted C=C bond and for the regiospecific introduction of a chiral fragment are exemplified in total syntheses of insect pheromones belonging to (Z)-trisubstituted alkenes. The bibliography includes 113 references.
20. Factors influencing pheromone trap effectiveness in attracting the banana weevil, Cosmopolites sordidus
NARCIS (Netherlands)
Tinzaara, W.; Gold, C.S.; Dicke, M.; Huis, van A.; Ragama, P.E.
2005-01-01
Studies were conducted in Uganda to evaluate the influence of distance, environmental factors, trap location and trap type on catches of Cosmopolites sordidus (Germar) (Coleoptera: Curculionidae) in pheromone-baited traps. Marked weevils were released at recorded locations within plots. Trap
1. Specialized odorant receptors in social insects that detect cuticular hydrocarbon cues and candidate pheromones.
Science.gov (United States)
Pask, Gregory M; Slone, Jesse D; Millar, Jocelyn G; Das, Prithwiraj; Moreira, Jardel A; Zhou, Xiaofan; Bello, Jan; Berger, Shelley L; Bonasio, Roberto; Desplan, Claude; Reinberg, Danny; Liebig, Jürgen; Zwiebel, Laurence J; Ray, Anandasankar
2017-08-17
Eusocial insects use cuticular hydrocarbons as components of pheromones that mediate social behaviours, such as caste and nestmate recognition, and regulation of reproduction. In ants such as Harpegnathos saltator, the queen produces a pheromone which suppresses the development of workers' ovaries and if she is removed, workers can transition to a reproductive state known as gamergate. Here we functionally characterize a subfamily of odorant receptors (Ors) with a nine-exon gene structure that have undergone a massive expansion in ants and other eusocial insects. We deorphanize 22 representative members and find they can detect cuticular hydrocarbons from different ant castes, with one (HsOr263) that responds strongly to gamergate extract and a candidate queen pheromone component. After systematic testing with a diverse panel of hydrocarbons, we find that most Harpegnathos saltator Ors are narrowly tuned, suggesting that several receptors must contribute to detection and discrimination of different cuticular hydrocarbons important in mediating eusocial behaviour.Cuticular hydrocarbons (CHC) mediate the interactions between individuals in eusocial insects, but the sensory receptors for CHCs are unclear. Here the authors show that in ants such as H. saltator, the 9-exon subfamily of odorant receptors (HsOrs) responds to CHCs, and ectopic expression of HsOrs in Drosophila neurons imparts responsiveness to CHCs.
2. Development of an efficient pheromone-based trapping method for the banana root borer Cosmopolites sordidus.
Science.gov (United States)
Reddy, G V P; Cruz, Z T; Guerrero, A
2009-01-01
The banana root borer Cosmopolites sordidus (Germar) (Coleoptera: Curculionidae) is a major pest of bananas throughout the world. Chemical control is both undesirable and expensive, where biological control alternatives are limited, and pheromone-based trapping results in low captures. In this study, several important factors that affect pheromone-based catches, such as trap type, trap dimensions, and color and position of the traps, were optimized. Ground traps were found to be superior to ramp and pitfall traps, and larger traps (40 x 25 cm and above) were more efficient than smaller ones (30 x 15 cm). In a color-choice test, the banana weevil clearly preferred brown traps over yellow, red, gray, blue, black, white, and green, with mahogany being more attractive than other shades of brown. In addition, pheromone baited ground traps positioned in the shade of the canopy caught significantly more adults than those placed in sunlight. Therefore, mahogany-brown ground traps 40 x 25 cm appear to be the most efficient at catching C. sordidus adults and have the greatest potential for use in mass trapping and programs for eradication of this pest.
3. The sxa2-dependent inactivation of the P-factor mating pheromone in the fission yeast Schizosaccharomyces pombe
DEFF Research Database (Denmark)
Ladds, G; Rasmussen, E M; Young, T
1996-01-01
Haploid cells of the fission yeast Schizosaccharomyces pombe exist in one of two mating types, referred to as M and P. Conjugation occurs between cells of opposite mating type and is controlled by the reciprocal action of diffusible pheromones. Loss of function of the sxa2 gene in M cells causes...... hypersensitivity to the P-factor mating pheromone and a reduction in mating efficiency. Here we demonstrate the secretion of an sxa2-dependent carboxypeptidase that inactivates P-factor by removal of the C-terminal leucine residue....
4. 'Does my Diet Affect my Perfume?' Identification and Quantification of Cuticular Compounds in Five Drosophila melanogaster Strains Maintained over 300 Generations on Different Diets.
Science.gov (United States)
Pavković-Lučić, Sofija; Todosijević, Marina; Savić, Tatjana; Vajs, Vlatka; Trajković, Jelena; Anđelković, Boban; Lučić, Luka; Krstić, Gordana; Makarov, Slobodan; Tomić, Vladimir; Miličić, Dragana; Vujisić, Ljubodrag
2016-02-01
Cuticular hydrocarbons (CHCs) in Drosophila melanogaster represent the basis of chemical communication being involved in many important biological functions. The aim of this study was to characterize chemical composition and variation of cuticular profiles in five D. melanogaster strains. These strains were reared for approximately 300 generations on five diets: standard cornmeal medium and substrates prepared with apple, banana, tomato, and carrot. Differences in quantity and/or quality in CHCs were assumed as a result of activation of different metabolic pathways involved in food digestion and adaptations to the particular diet type. In total, independently of sex and strain, 66 chemical compounds were identified. In females of all strains, 60 compounds were identified, while, in males, 47 compounds were extracted. Certain new chemical compounds for D. melanogaster were fo | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 1, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.5259804129600525, "perplexity": 16672.01747249267}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2022-40/segments/1664030334514.38/warc/CC-MAIN-20220925035541-20220925065541-00480.warc.gz"} |
http://www.numdam.org/item/AIF_1970__20_2_45_0/ | Theorems of Krein Milman type for certain convex sets of functions operators
Annales de l'Institut Fourier, Tome 20 (1970) no. 2, p. 45-54
On donne des conditions suffisantes sous lesquelles, pour un convexe borné fermé $B$ d’un espace localement convexe réel $E$, l’ensemble $C\left(X,B\right)$ [des fonctions continues de l’espace compact $X$ dans $B$] est l’enveloppe convexe uniformément fermée dans $C\left(X,E\right)$ de ses points extrémaux. On applique ces résultats à la boule unité de l’espace d’opérateurs bornés (ou compacts, ou faiblement compacts) de certains espaces de Banach dans $C\left(X\right)$.
Sufficient conditions are given in order that, for a bounded closed convex subset $B$ of a locally convex space $E$, the set $C\left(X,B\right)$ of continuous functions from the compact space $X$ into $B$, is the uniformly closed convex hull in $C\left(X,E\right)$ of its extreme points. Applications are made to the unit ball of bounded (or compact, or weakly compact) operators from certain Banach spaces into $C\left(X\right)$.
@article{AIF_1970__20_2_45_0,
author = {Phelps, Robert R.},
title = {Theorems of Krein Milman type for certain convex sets of functions operators},
journal = {Annales de l'Institut Fourier},
publisher = {Imprimerie Durand},
volume = {20},
number = {2},
year = {1970},
pages = {45-54},
doi = {10.5802/aif.351},
zbl = {0195.40807},
mrnumber = {44 \#4501},
language = {en},
url = {http://www.numdam.org/item/AIF_1970__20_2_45_0}
}
Phelps, Robert R. Theorems of Krein Milman type for certain convex sets of functions operators. Annales de l'Institut Fourier, Tome 20 (1970) no. 2, pp. 45-54. doi : 10.5802/aif.351. http://www.numdam.org/item/AIF_1970__20_2_45_0/
[1] Erret Bishop and R. R. Phelps, The support functionals of a convex set, Proc. Symp. Pure Math. vol 7 (Convexity), A.M.S. (1963), p. 27-35. | MR 27 #4051 | Zbl 0149.08601
[2] R. M. Blumenthal, J. Lindenstrauss and R. R. Phelps, Extreme operators into C(K), Pacific J. Math. 15 (1965), p. 747-756. | MR 35 #758 | Zbl 0141.32101
[3] N. Bourbaki, Espaces vectoriels topologiques, Ch. 1 et 2, 2e édition, Paris, 1966.
[4] N. Dinculeanu, Vector measures, Berlin, 1967.
[5] N. Dunford and J. T. Schwartz, Linear operators Part I, (1958), Interscience. | Zbl 0084.10402
[6] P. D. Morris and R. R. Phelps, Theorems of Krein-Milman type for certain convex sets of operators, Trans. Amer. Math. Soc. 150 (1970), 183-200. | MR 41 #7409 | Zbl 0198.46601
[7] G. Seever, Generalization of a theorem of Lindenstrauss (dittoed notes). | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 14, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 1, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.5347829461097717, "perplexity": 3540.6740090445514}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2019-13/segments/1552912203493.88/warc/CC-MAIN-20190324210143-20190324232143-00406.warc.gz"} |
https://chemistry.stackexchange.com/questions/28449/bonding-and-phase-changes | # Bonding and Phase Changes?
When water boils into water vapor, its temperature (average kinetic energy) does not change because the inputed energy is used to break its bonds. But how does that work?
Also, in a liquid, aren’t intermolecular bonds broken and reformed constantly anyway? Why does a phase change require a time interval for breaking bonds?
Temperature involves kinetic energy; however, bonds and intermolecular forces (IMF's) involve potential energy. The potential energy of the system increases when water vaporizes, but kinetic energy does not change.
In a liquid, for each IMF broken, another is made, resulting in a net change of zero.
A phase change requires a time interval because it takes time to add energy to the system.
• +1. Indeed the answer lies within the word "potential". – M.A.R. ಠ_ಠ Apr 9 '15 at 17:38
• Wait, the potential energy of the system increases when bonds are being broken? – lightweaver Apr 10 '15 at 11:19
• Yes. When two objects that are attracted to each other by a force are moved farther apart, potential energy increases. – Brinn Belyea Apr 13 '15 at 13:39
The trivial reason that the phase change liquid to vapour takes time is that this can only occur at the surface of a liquid, but I suspect that this is not what you mean when you talk about a ‘time interval’ to break bonds. In fact time does not come into it. I try to explain what happens below. I've added some background also in case you are not familiar with it; if you are you need only read the paras around the figure.
Boiling occurs when the vapour pressure of the liquid equals the external pressure, normally 1 atm (or 1 bar; almost the same thing). To boil a liquid, energy has to be continuously suppled as molecules are escaping as vapour and taking energy away with them in doing so. (Holding a rapidly evaporating solvent feels cold). At the boiling point the temperature remains constant until all the liquid has evaporated.
The average energy a liquid or gas has at temperature T is $3k_BT/2$. Trouton’s rule states that the latent heat (enthalpy) of vaporisation is related to the boiling temperature $T_B$ as $L_{vap} /T_B \approx 80 \pu {J K^{-1}mol^{-1}}$. This borne out by many liquids, with a range of $\pu{70 - 90 J K^{-1}mol^{-1}}$; those with values greater than this range are hydrogen bonded, e.g. water, ethanol, and if less than this range, form dimers in the vapour, e.g. acetic acid. From this value the cohesive energy can be estimated and comes to $\approx 9 k_BT$. By cohesive energy is meant all the pairwise interactions between one molecule and its neighbours. Thus molecules will condense to form liquids when their cohesive energy exceeds $\approx 9 k_BT$. Thus to reverse the process, which is most quickly done by boiling, this much energy has to be supplied per molecule.
Energy is present in a molecule as both kinetic (translation plus vibrations/ & rotations ) and potential(bonds). In addition, when in a liquid there is always inter-molecular potential energy, e.g. via pairwise dispersion forces, which are always present between any atom or molecule, and dipole and induced dipole forces etc, which are generally called van-der-Waals forces. These form the cohesive energy. (We shall assume that chemical bonds are so strong that boiling does not change them which is usually the case. This makes hydrogen bonds inter-molecular bonds).
As you mention in your question inter-molecular bonds are made and broken all the time and this because there is a distribution of energies. The Boltzmann eqn. $\ce{exp}(-E/(k_BT))$ gives the chance of having energy E. This distribution of energies is also why it is possible for a liquid to evaporate at room temperature, albeit slowly compared to boiling, as a few molecules / second will randomly gain enough energy to escape the liquid.
The nature of these intermolecular forces is important. At infinite separation the intermolecular potential energy is zero, as molecules approach one another the potential energy falls (an attractive interaction) and reaches a minimum value, say, at 0.5 nm or some similar small separation which is somewhat larger than a chemical bond length. At yet smaller separation there is strong repulsion between the electrons on either molecule and the potential energy rises very rapidly. In practice ‘infinite separation’ can mean just 3 or 4 times the minimum, equilibrium separation. The shape of the inter-molecular potential typically has the form given by a Lennard-Jones or Morse equation. See the figure for a sketch, which is not to scale.
The minimum energy is negative. Note that if the intermolecular potential were harmonic in form, then liquids could never evaporate as the harmonic potential energy extends to infinity.
As the average energy increases the cohesive (intermolecular) potential energy increases also until it reaches zero and only kinetic (internal and translational, rotational) is left. The molecules can now escape the solution.
(Finally, note that a molecule has the same average kinetic energy in the liquid or vapour at the same temperature and is $3k_BT/2$. In the liquid the motion is restricted to a smaller space around the potential energy minimum than it is in the gas phase.) | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 1, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.8794780373573303, "perplexity": 623.8315999650938}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2019-26/segments/1560627999838.23/warc/CC-MAIN-20190625112522-20190625134522-00388.warc.gz"} |
https://ham.stackexchange.com/questions/1410/what-is-the-peak-voltage-at-the-tips-of-a-dipole-antenna/1422#1422 | # What is the peak voltage at the tips of a dipole antenna?
What is the peak voltage present at the very end tips of half-wave dipole antenna in free space, and how might this peak voltage relate to transmitter type, transmitter power, RF frequency vs. antenna half-wave frequency mismatch, feed line, SWR, wire diameter, and etc.
I'm going to approach this a little differently starting from roughly the same place. Here I am going to use a resonant $\lambda$/2 20m dipole driven by 100 W as the model.
Let's compute the current at the feed point of a dipole at resonance, this is found with the input power (100 watts) and the feed point impedance; which for our dipole is assumed to be the theoretical 73 $\Omega$ :
$$I = \left(\frac{W}{R}\right)^{\frac{1}{2}} = \left(\frac{100 \mathrm W}{73 \Omega}\right)^{\frac{1}{2}} = 1.17 \: \text{amps (RMS)}$$
Therefore the driving voltage can be calulated with Ohm's Law:
$$V_\text{feed} = I \cdot R = 1.17 \mathrm A_\text{RMS} \cdot 73 \Omega = 85.44 \:\mathrm V_\text{RMS}$$ (unmodulated signal)
The voltage at the end of the dipole would require us to calculate the Q and solve the following:
$$V_\text{end} = \frac{Q\:V_\text{feed}}{2}$$
Trying to minimize the hand-waving, we can use some approximations from transmission line theory to give us the Q. (See Edmund Laport's Radio Antenna Engineering for a complete (and math heavy) explanation) To do this we need the characteristic impedance of the dipole (considered as a transmission line). That is given by:
$$Z_{0} = 276 \cdot \log_{10}\frac{l}{p} = 972.31 \Omega$$
Where $l$ is the total length of the dipole and $p$ is the radius of the conductor (all in the same units). I am going to ignore calculating the exact length here, we know it's approximately 5% shorter than the real wavelength to make up for velocity factor and end effects. This next bit leans on transmission line theory and can turn into a bag of snakes, if you want to know more about where these equations come from, check the reference quoted above. $Q$ here is the ratio of the voltage of the direct wave and the reflected wave:
$$Q = \frac{1+m}{1-m}$$
and $m$ is calculated from the feed point impedance $R$ and the characteristic impedance $Z_0$:
$$m = \frac{Z_0-R}{Z_0+R}$$
When I calculate $\ Z_0$, I am going to assume our dipole is made with 3mm wire. Now to crank through the numbers:
$$m = \frac{972\Omega-73\Omega}{972\Omega+73\Omega} = .86$$
$$Q = \frac{1+.86}{1-.86} = 13.29$$
Now we can solve for $V_\text{end}$:
$$V_\text{end} = \frac{(13.29 \cdot 85.44 \mathrm V)}{2} = 568 \:\mathrm V_\text{RMS}$$
Again, this is the RMS voltage we should convert to peak voltage:
$$568 \:\mathrm V_\text{RMS} \cdot \sqrt{2} = \pm 804 \:\mathrm V_\text{peak}$$
This is all for 100W, if we instead plug 1500W into the above math, we come up with
$$4397 \:\mathrm V_\text{RMS} \:\text{or} \: \pm 6200 \:\mathrm V_\text{peak}$$
That's a pretty hefty jolt. So getting back to the OP's other questions, the input power has a substantial effect on the voltage. The rest of the factors are all the same as for maximizing antenna efficiency (resonance, conductor size, etc.)
EDIT: Most of the above equations come from the section on Circuital Design in the reference listed above. The book is more math heavy than typical amateur radio references, but not as bad as some of the more modern engineering texts. It's slow going, but a worthwhile read.
• An interesting consequence of this which I had not previously considered: a thicker antenna will have a lower peak voltage. (And also: wider bandwidth, lower resistive losses. Overall a win.) Feb 12 '14 at 16:07
• Would the reported computation be equivalent to this (since you already computed the characteristic impedance) 972.31 Ohm * 1.17 Amps / 2 = 568 V (rms) ? Mar 26 '18 at 22:56
• In running through the numbers, it appears you used the wire size diameter, rather than the radius as called for in the formulas cited. Wire size of 3mm would have a radius of .0015, but the calculation appears to use diameter of 3mm (.003m) or approximately 10AWG wire. Or did you mean to say that you used 6mm diameter wire? At 1500W, then, the V-pk is closer to ±6881V-pk at 14.2Mhz, for example, versus the ±6200 calculated. Can you comment on how this method applies to the voltage(s) at the end of an elevated Ground Plane (tip of radiator and ends of 4x radials)?
– K1VF
Nov 11 '18 at 15:47
• Z0=276⋅log10lp=972.31Ω Where does 276 come from in this formula? And will this value (276) change in a 50 ohm dipole antenna? Please help me for my calculate tnx. Met Nov 4 '20 at 12:20
• @HAMRADIO Apparently I slept since I wrote this post. I have been out of radio for some years. Looking back through these equations, I can see why you are confused about the number, but I can't think of it myself, it must have come from the textbook. Nov 5 '20 at 18:35
It's really hard to say, because it depends on so many things. Analyzing the antenna in free space simplifies some things, but we'd still have to consider the exact geometry of the antenna (How thick are the wires? Are they bent at all?) and the material from which they are made (any resistance will decrease the Q factor of the antenna, reducing the peak voltage).
However, if you look to analysis of end-fed dipoles, you can find that it's been determined empirically and by modeling that the impedance at the end of a real half-wave dipole is somewhere between 1800 to 5000 ohms.
Knowing this, we can calculate what the voltage is for a given power into the antenna. If we are putting 100W into the antenna, and we figure the impedance at the ends is 4000 ohms, then:
\begin{align} P &= V^2/R \\ 100\mathrm W &= V^2 / 4000\Omega \\ \sqrt{100\mathrm W \cdot 4000 \Omega} &= V \\ V &\approx 632 \mathrm V \end{align}
This is an RMS value. Knowing that our transmission is approximately sinusoidal, then the peak voltage is something like:
$$632 \cdot \sqrt{2} = \pm 894 \mathrm V$$
From the above equations, we can see that power is proportional to the square of voltage:
$$P \propto V^2$$
This is the power delivered to the antenna. Transmitter type and the match to the antenna (SWR) are relevant only to the extent that they change the power delivered to the antenna.
This is all assuming that the antenna is operated at resonance. As the frequency moves away from resonance, the peak voltage decreases. The reason why is simple: this high voltage is attainable because each cycle reinforces the previous. If you take a limiting case where the antenna is operated at DC, the voltage at the ends is equal to the voltage at the feedpoint, because there is no resonance to reinforce the voltage at the ends.
For those of you with EZNEC or some other antenna modeling software, there is a way to answer this question using EZNEC. Model a 1/4WL stub in free space taking care not to violate any geometry checks. Put a 100w source at one end of the stub and a 10 megohm load at the other end of the stub. Adjust the stub length and user defined wire loss to obtain the resistive feedpoint impedance of a dipole looking into the stub. Then display the load data. It will tell you the voltage at the end of a dipole. I set my 4 MHz stub for 70 ohms and got 879 volts across the 10 megohm load resistor. The additional user defined wire loss is equivalent to the power lost from the dipole through radiation.
• Cecil! It's good to see you here! Gentlemen, welcome another BSEE! :-) Nov 12 '18 at 0:09 | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 1, "mathjax_display_tex": 1, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 1, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.9409974813461304, "perplexity": 753.487097963973}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2021-39/segments/1631780061350.42/warc/CC-MAIN-20210929004757-20210929034757-00531.warc.gz"} |
https://chemistry.stackexchange.com/questions/81630/the-affect-of-effective-nuclear-charge-on-energy-gap-between-subshells | # The affect of effective nuclear charge on energy gap between subshells
A few days ago my teacher taught me about $\mathrm{d}$ orbital contraction. He said that in $\ce{SF6}$ the hybridization of sulphur is $\mathrm{sp^3d^2}$. He said that although the $\mathrm{d}$ orbital is higher in energy than $\mathrm{s}$ and $\mathrm{p}$ orbitals due to increase in positive charge on sulphur, due to high electronegativity of flourine the $\mathrm{d}$ orbitals contract more than $\mathrm{s}$ and $\mathrm{p}$ orbitals, hence the difference in energy decreases and $\mathrm{d}$ orbital can participate in hybridization.
There was no problem with the explanation as it seemed perfectly plausible. But today, while teaching MOT, he told that the gap between $\mathrm{2s}$ and $\mathrm{2p}$ orbitals increases as we move from lithium to flourine due to increase in effective nuclear charge and interelectronic repulsion, which is quite opposite to what he told some days ago.
What am I missing? Which of the following interpretation is correct? A qualitative explanation involving less of quantum mechanics is that I want and involving MOT and VBT only because I know only those theories. According to advanced theories d orbitals will not participate in bonding in SF6 but according to VBT they will. As I already mentioned that I know only VBT and MOT so I have asked the question in the context of these two theories. | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 1, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.9163514971733093, "perplexity": 605.5238413350172}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2022-49/segments/1669446710890.97/warc/CC-MAIN-20221202014312-20221202044312-00432.warc.gz"} |
https://www.scipopt.org/doc-7.0.0/html/type__stat_8h_source.php | # SCIP
Solving Constraint Integer Programs
type_stat.h
Go to the documentation of this file.
1 /* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
2 /* */
3 /* This file is part of the program and library */
4 /* SCIP --- Solving Constraint Integer Programs */
5 /* */
7 /* fuer Informationstechnik Berlin */
8 /* */
10 /* */
12 /* along with SCIP; see the file COPYING. If not visit scipopt.org. */
13 /* */
14 /* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
15
16 /**@file type_stat.h
17 * @brief type definitions for problem statistics
18 * @author Tobias Achterberg
19 */
20
21 /*---+----1----+----2----+----3----+----4----+----5----+----6----+----7----+----8----+----9----+----0----+----1----+----2*/
22
23 #ifndef __SCIP_TYPE_STAT_H__
24 #define __SCIP_TYPE_STAT_H__
25
26 #ifdef __cplusplus
27 extern "C" {
28 #endif
29
30 /** SCIP solving status */
32 {
33 SCIP_STATUS_UNKNOWN = 0, /**< the solving status is not yet known */
34 SCIP_STATUS_USERINTERRUPT = 1, /**< the user interrupted the solving process (by pressing CTRL-C) */
35 SCIP_STATUS_NODELIMIT = 2, /**< the solving process was interrupted because the node limit was reached */
36 SCIP_STATUS_TOTALNODELIMIT = 3, /**< the solving process was interrupted because the total node limit was
37 * reached (incl. restarts)
38 */
39 SCIP_STATUS_STALLNODELIMIT = 4, /**< the solving process was interrupted because the stalling node limit was
40 * reached (no inprovement w.r.t. primal bound)
41 */
42 SCIP_STATUS_TIMELIMIT = 5, /**< the solving process was interrupted because the time limit was reached */
43 SCIP_STATUS_MEMLIMIT = 6, /**< the solving process was interrupted because the memory limit was reached */
44 SCIP_STATUS_GAPLIMIT = 7, /**< the solving process was interrupted because the gap limit was reached */
45 SCIP_STATUS_SOLLIMIT = 8, /**< the solving process was interrupted because the solution limit was
46 * reached
47 */
48 SCIP_STATUS_BESTSOLLIMIT = 9, /**< the solving process was interrupted because the solution improvement limit
49 * was reached
50 */
51 SCIP_STATUS_RESTARTLIMIT = 10, /**< the solving process was interrupted because the restart limit was reached */
52 SCIP_STATUS_OPTIMAL = 11, /**< the problem was solved to optimality, an optimal solution is available */
53 SCIP_STATUS_INFEASIBLE = 12, /**< the problem was proven to be infeasible */
54 SCIP_STATUS_UNBOUNDED = 13, /**< the problem was proven to be unbounded */
55 SCIP_STATUS_INFORUNBD = 14, /**< the problem was proven to be either infeasible or unbounded */
56 SCIP_STATUS_TERMINATE = 15 /**< status if the process received a SIGTERM signal */
57 };
58 typedef enum SCIP_Status SCIP_STATUS;
59
60 typedef struct SCIP_Stat SCIP_STAT; /**< problem and runtime specific statistics */
61
62 #ifdef __cplusplus
63 }
64 #endif
65
66 #endif
enum SCIP_Status SCIP_STATUS
Definition: type_stat.h:58
SCIP_Status
Definition: type_stat.h:31 | {"extraction_info": {"found_math": false, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.8525447845458984, "perplexity": 2575.6004918128865}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2021-39/segments/1631780053717.37/warc/CC-MAIN-20210916174455-20210916204455-00282.warc.gz"} |
https://indico.cern.ch/event/443176/contributions/2151917/ | # SUSY 2016
Jul 3 – 8, 2016
The University of Melbourne
Australia/Melbourne timezone
## Top-philic Scalar DM with a Vector-like Top Partner
Jul 7, 2016, 3:00 PM
20m
Carillo Gantner Theatre
### Carillo Gantner Theatre
Carrillo Gantner Theatre, Sidney Myer Asia Centre The University of Melbourne VIC 3010 Australia
Talk Dark Matter and Particle Astrophysics
### Speaker
Peiwen Wu (Korea Institute for Advanced Study (KIAS))
### Description
We consider a scalar top-philic Dark Matter (DM) $S$ coupling, apart from the Higgs portal, exclusively to the right-handed top quark $t_R$ and a colored vector-like top partner $T$ with a Yukawa coupling $y_{ST}$ which we call the topVL portal. When the Higgs portal is closed and $y_{ST}$ is perturbative $(<1)$, $TS\to (W^+b, gt)$, $SS\to t\bar{t}$ and $T\bar{T}\to (q\bar{q},gg)$ provide the dominant annihilation contributions to obtain the correct thermal relic density in light, medium and heavy DM mass range, respectively. However, large $y_{ST}\sim\mathcal{O}(10)$ can make $SS\to gg$ dominate via the loop-induced coupling $C_{SSgg}$ in the $m_S < m_t$ region. In this model it is the $C_{SSgg}$ coupling that dominates DM-nucleon scattering in the direct detection, which can be large when $SS\to gg$ dominates the DM annihilation. The current LUX results can exclude the $SS\to gg$ dominating scenario and the expected sensitivity of XENON-1T may further test $y_{ST} > 1$, and $0.5 < y_{ST} < 1$ may be covered in the future LUX-ZP experiment. The indirect detection results from Fermi gamma-ray observations can also exclude the $SS\to gg$ dominating scenario and play a complementary role to direct detection in the heavy DM mass region, of which one order of magnitude of sensitivity improvement will push DM mass to be heavier than about 400, 600, 1000 GeV for $y_{ST}=0.3, 0.5, 1.0$, respectively. The colored top partner $T$ and its anti-particle can be produced in pair at the hadron collider. They will decay $100\%$ into $t\bar{t}+E^{miss}_T$ signal when kinematically open and receive constraints from the corresponding CMS measurements at 8 TeV. We found that the top partner mass in the range 300 (450)-850 GeV can be excluded for $m_S$ =0 (200) GeV.
### Primary author
Peiwen Wu (Korea Institute for Advanced Study (KIAS))
### Co-authors
Prof. Seungwon Baek (Korea Institute for Advanced Study (KIAS)) pyungwon ko (Korea Inst. for Advanced Study (KIAS)) | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 1, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.8546288013458252, "perplexity": 2989.5683707071075}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2022-40/segments/1664030334974.57/warc/CC-MAIN-20220927002241-20220927032241-00146.warc.gz"} |
https://www.transtutors.com/questions/1-consider-the-element-and-the-coordinate-systems-x-and-x-shown-in-figure-below-5-po-2635354.htm | # 1. Consider the element and the coordinate systems x and X shown in figure below. (5 points) Assu...
1. Consider the element and the coordinate systems x and X shown in figure below. (5 points) Assuming the linear variation for the dependent variable, T, is as follows: a) Derive the finite element shape (interpolation) functions x) and S,(x) by solving ch and c2 the shape functions obtained satisfy the Lagrangian properties. c) Find the transformation between the coordinate systems x and X d) Using the transformation in (c), express the shape functions found in (a), in terms of X
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https://testbook.com/objective-questions/mcq-on-motion-in-a-magnetic-field--5eea6a1339140f30f369ef80 | # A particle of charge e and mass m moves with a velocity v in a magnetic field B applied perpendicular to the motion of the particle. The radius r of its path in the field is _______
1. $$\frac{mv}{Be}$$
2. $$\frac{Be}{mv}$$
3. $$\frac{ev}{Bm}$$
4. $$\frac{Bv}{em}$$
## Answer (Detailed Solution Below)
Option 1 : $$\frac{mv}{Be}$$
## Motion in a Magnetic Field MCQ Question 1 Detailed Solution
CONCEPT:
• When moving through a magnetic field, the charged particle experiences a force.
• When the direction of the velocity of the charged particle is perpendicular to the magnetic field:
• Magnetic force is always perpendicular to velocity and the field by the Right-Hand Rule.
• And the particle starts to follow a curved path.
• The particle continuously follows this curved path until it forms a complete circle.
• This magnetic force works as the centripetal force.
• Centripetal force (FC) = Magnetic force (FB)
⇒ qvB = mv2/R
⇒ R = mv/qB
where q is the charge on the particle, v is the velocity of it, m is the mass of the particle, B is the magnetic field in space where it circles, and R is the radius of the circle in which it moves.
EXPLANATION:
Given that particle has charge e; mass = m; and moves with a velocity v in a magnetic field B. So
• Centripetal force (FC) = Magnetic force (FB)
⇒ qvB = mv2/R
$$\Rightarrow R=\frac{mv}{qB}$$
$$\Rightarrow r=\frac{mv}{Be}$$
So the correct answer is option 1.
# What will be the direction of a magnetic field if an alpha particle projected towards the north is deflected towards East by a magnetic field?
1. Towards South
2. Upward
3. Towards East
4. Downwards
## Answer (Detailed Solution Below)
Option 2 : Upward
## Motion in a Magnetic Field MCQ Question 2 Detailed Solution
CONCEPT:
• Fleming Left-hand rule gives the force experienced by a charged particle moving in a magnetic field or a current-carrying wire placed in a magnetic field.
• It states that "stretch the thumb, the forefinger, and the central finger of the left hand so that they are mutually perpendicular to each other. If the forefinger points in the direction of the magnetic field, the central finger points in the direction of motion of charge, then the thumb points in the direction of force experienced by positively charged particles."
Force is given by:
F = q v B
Where F is force, q is a charge, v is velocity and B is the magnetic field.
EXPLANATION:
• Here the alpha particle projected towards the north i.e current is towards the north (middle finger).
• Particle deflects towards east i.e direction of force is towards the east (thumb).
• So the direction of a magnetic field will be in the upward direction (forefinger). So option 2 is correct.
# When an alpha particle with mass m, charge 2e enters into a magnetic field B with velocity v perpendicular to the direction of the magnetic field, the radius of the curved path will be ____________.
1. $${mv \over eB}$$
2. $${mv \over 2eB}$$
3. $${2mv \over eB}$$
4. $${mv \over 4eB}$$
## Answer (Detailed Solution Below)
Option 2 : $${mv \over 2eB}$$
## Motion in a Magnetic Field MCQ Question 3 Detailed Solution
CONCEPT:
• When moving through a magnetic field, the charged particle experiences a force.
• When the direction of the velocity of the charged particle is perpendicular to the magnetic field:
• Magnetic force is always perpendicular to velocity and the field by the Right-Hand Rule.
• And the particle starts to follow a curved path.
• The particle continuously follows this curved path until it forms a complete circle.
• This magnetic force works as the centripetal force.
Centripetal force (FC) = Magnetic force (FB)
q v B = mv2/R
R = mv/qB
where q is the charge on the particle, v is the velocity of it, m is the mass of the particle, B is the magnetic field in space where it circles, and R is the radius of the circle in which it moves.
EXPLANATION:
• When a charge moves through a magnetic field in a perpendicular direction, it will move in a circular motion as explained above with a radius
R = mv/qB
For alpha particle according to the question mass is m, velocity is v, the charge is 2e, and the magnetic field is B. So
$$R={mv \over qB}={mv \over (2e)B}$$
• So the correct answer is option 2.
# When a charged particle enters into a magnetic field with velocity perpendicular to the direction of the magnetic field. The particle follows a curved path. What will happen to the radius of this curved path if the magnetic field is increased?
1. particle goes in straight line.
2. radius will remain same
3. radius will increase
4. radius will decrease
## Answer (Detailed Solution Below)
Option 4 : radius will decrease
## Motion in a Magnetic Field MCQ Question 4 Detailed Solution
CONCEPT:
• When moving through a magnetic field, the charged particle experiences a force.
• When the direction of the velocity of the charged particle is perpendicular to the magnetic field:
• Magnetic force is always perpendicular to velocity and the field by the Right-Hand Rule.
• And the particle starts to follow a curved path.
• The particle continuously follows this curved path until it forms a complete circle.
• This magnetic force works as the centripetal force.
Centripetal force (FC) = Magnetic force (FB)
q v B = mv2/R
R = mv/qB
where q is the charge on the particle, v is the velocity of it, m is the mass of the particle, B is the magnetic field in space where it circles, and R is the radius of the circle in which it moves.
EXPLANATION:
• When a charge moves through a magnetic field in a perpendicular direction, it will move in a circular motion as explained above with a radius
$$R={mv \over qB}$$
$$R\alpha{1 \over B}$$
• So the radius of the curved path is inversely proportional to the magnetic field.
• So as the magnetic field increases, the radius of the curved path will decrease.
• Hence the correct answer is option 4.
# A charged particle with velocity v and charge q passes through a magnetic field B. What will be the force on it due to magnetic field given that the velocity is along the direction of magnetic field?
1. 0
2. qv2B
3. qv/B
4. qvB
Option 1 : 0
## Motion in a Magnetic Field MCQ Question 5 Detailed Solution
CONCEPT:
• When moving through a magnetic field, the charged particle experiences a force.
• This force is given by the charge times the vector product of velocity and magnetic field.
$$F = q (\vec{v}\times \vec{B}) =qvBsinθ$$
where q is the charge on particle, v is perpendicular velocity and B is the magnetic field, θ is the angle between v and B.
EXPLANATION:
Force on a charged particle in a magnetic field is given by
$$F = qvBsinθ$$
• Since the velocity and magnetic field are in the same direction. The angle between them will be 0°.
θ = 0°
$$F = qvBsinθ= qvBsin0=0$$
• Hence the magnetic force on it will be 0.
• So the correct answer is option 1.
# A charge moves in a circle perpendicular to a magnetic field. The time period of revolution is independent of :
1. velocity
2. mass
3. charge
4. magnetic field
## Answer (Detailed Solution Below)
Option 1 : velocity
## Motion in a Magnetic Field MCQ Question 6 Detailed Solution
CONCEPT:
• Lorentz force: It is defined as the force exerted on a charged particle q moving with velocity v through an electric field E and magnetic field B. The entire electromagnetic force on the charged particle is called the Lorentz force and is given by
⇒ FL = qE + qvBsinθ
• charged particle experiences a force when it moves in a magnetic field.
⇒ F = qvBsinθ
Where, F = force due to magnetic field, q = magnitude of charge, v = speed of charge, B = magnetic field and θ = angle between v and B
CALCULATION:
• When the velocity of a charged particle is perpendicular to a magnetic field, it describes a circle and the radius of the circle is given by:
$$⇒ r=\frac{mv}{qB}$$ -----(1)
• Time is taken by a charged particle to complete one revolution.
$$\Rightarrow T=\frac{2\pi r}{v}$$ -----(2)
Where T = time period
From equation 1 and equation 2, we get
$$\Rightarrow T=\frac{2\pi m}{qB}$$
• From the above equation, it is clear that the time period depends on mass, charge, and magnetic field but it is independent of velocity.
• Hence, option 1 is correct.
# A charge particle is moving perpendicular to a uniform magnetic field. Which quantity will change:
1. Speed
2. Velocity
3. Direction of motion
4. Both option 2 and 3
## Answer (Detailed Solution Below)
Option 4 : Both option 2 and 3
## Motion in a Magnetic Field MCQ Question 7 Detailed Solution
CONCEPT:
• A charged particle experiences a force when it moves in a magnetic field.
⇒ F = qvBsinθ
Where, F = force due to magnetic field, q = magnitude of charge, v = velocity of charge, B = magnetic field, and θ = angle between v and B
• When the velocity of a charged particle is perpendicular to a magnetic field, it describes a circle and the radius of the circle is given by:
$$⇒ r=\frac{mv}{qB}$$
EXPLANATION:
• When a charged particle moves perpendicular (θ = 90°) to the magnetic field, the force experienced by it is given as,
⇒ F = qvBsin(90)
⇒ F = qvB [∵ sin(90) = 1]
• According to Newton's first law of motion, a body will accelerate if a force acts on the body.
• Since a force act on the charged particle when it moves perpendicular to a uniform magnetic field so it will accelerate and the velocity will change.
• When the velocity of a charged particle is perpendicular to a magnetic field, it describes a circle. So its direction will also change.
• Hence, option 4 is correct.
# When a charged particle moves through a perpendicular magnetic field, it undergoes a change in its
1. energy
2. mass
3. speed
4. direction of motion
## Answer (Detailed Solution Below)
Option 4 : direction of motion
## Motion in a Magnetic Field MCQ Question 8 Detailed Solution
CONCEPT:
The motion of the charged particle in a uniform magnetic field:
• When a charged particle q enters a magnetic field $$\vec B$$ with velocity $$\vec v$$, it experiences a force
$$⇒ \vec F = q\left( {\vec v \times \vec B} \right)$$
• The direction of this force is perpendicular to both $$\vec v$$ and $$\vec B$$. The magnitude of this force is
⇒ F = qvB sin θ
EXPLANATION:
• The direction of this force is perpendicular to both $$\vec v$$ and $$\vec B$$ and the magnitude of this force is given as
⇒ F = qvB sin θ
• If a charged particle enters a magnetic field with velocity v such that the direction between the velocity of the charged particle q and magnetic field B is 90°, then it experiences a maximum force.
Here θ = 90°, so
⇒ F = qvB sin 90° = qvB = a maximum force
• As the magnetic force acts on a particle perpendicular to its velocity, it does not do any work on the particle. It does not change the kinetic energy or the speed of the particle.
• The magnetic field B is perpendicular to the paper and going into it (show by small cross).
• A charge +q is projected with speed v in the plane of the paper. The velocity is perpendicular to the magnetic field. A force F = qvB acts on the particle perpendicular to both $$\vec v$$ and $$\vec B$$.
• This force continuously deflects the particle sideways without changing its speed and the particle will move along a circle perpendicular to the field. Therefore option 4 is correct.
# A strong magnetic field is applied on a stationary electron. Then the electron:
1. remains stationary
2. moves perpendicular to the direction of magnetic field
3. moves in the direction of magnetic field
4. moves opposite to the direction of magnetic field
## Answer (Detailed Solution Below)
Option 1 : remains stationary
## Motion in a Magnetic Field MCQ Question 9 Detailed Solution
The correct answer is option 1) i.e. remains stationary
CONCEPT:
• Lorentz force: A charged particle moving relative to a magnetic field experiences a force due to the magnetic field. This force is called the Lorentz force.
• When a charged particle q is moving with a velocity of v in a magnetic field of intensity B, the Lorentz force (F) is given by:
$$\Rightarrow \vec{F} = q(\vec{v}\times \vec{B})$$
EXPLANATION:
In the given situation, the electron is stationary i.e. its velocity, $$\vec{v} = 0$$
• Therefore, the force on a stationary electron is
$$\Rightarrow \vec{F} = q(\vec{v}\times \vec{B}) = q(0\times \vec{B}) =0$$
• Hence the electron experiences zero force due to the applied magnetic field and thus remains stationary.
# Which of the following particle will not experience any magnetic force in a magnetic field?
1. A proton moving in a magnetic field
2. An electron moving in a magnetic field
3. An alpha particle moving in a magnetic field
4. A neutron moving in a magnetic field
## Answer (Detailed Solution Below)
Option 4 : A neutron moving in a magnetic field
## Motion in a Magnetic Field MCQ Question 10 Detailed Solution
CONCEPT:
Magnetic field (B):
• The region or space around a current-carrying wire or around a magnet in which magnetic force can be experienced by other magnets is called a magnetic field.
• When a moving charged particle enters a magnetic field then the path followed by the charged particle is circular if the magnetic field is perpendicular to the velocity of the particle.
• While moving through a magnetic field, the charged particle experiences a force.
• This force is given by the charge times the vector product of velocity and magnetic field.
$$F = q (\vec{v}\times \vec{B})$$
where q is the charge on particle, v is perpendicular velocity and B is the magnetic field.
EXPLANATION:
• According to the above discussion, it is clear that the magnetic force can act only on moving charged particles, magnets, and current element.
• So there will be a magnetic force on electrons, protons, and alpha particles. Because they have a charge and they are moving.
But for a neutron, q = 0
$$F = q (\vec{v}\times \vec{B}) = 0$$
• Thus a neutron moving in a magnetic field will not experience any magnetic force.
# Which of the following particles will not be deflected when subjected to an external magnetic field?
1. Proton
2. Positron
3. Photon
4. Deuteron
## Answer (Detailed Solution Below)
Option 3 : Photon
## Motion in a Magnetic Field MCQ Question 11 Detailed Solution
CONCEPT:
• The space or region around the electric charge in which electrostatic force can be experienced by other charged particles is called an electric field by that electric charge.
• The imaginary lines which are used to represent the electric field are called as electric field line.
• The tangent line at a point on the electric field line gives the direction of the electric field at that point.
• The field lines emerge from a positive charge and terminate at a negative charge.
• Whenever a charged particle enters a magnetic field, it experiences a force and the magnitude of this force is given by
⇒ F = qvB sin θ
EXPLANATION:
• A photon is a tiny light particle that comprises waves of electromagnetic radiation.
• James Maxwell observed photons are just electric fields traveling through space.
• Photons have no charge and no resting mass. Therefore it is not deflected by an external magnetic field. Hence option 3 is correct.
• Whereas protonpositron, and deuteron possess charge and thus are deflected by an external magnetic field.
# When an electron enters a perpendicular magnetic field, the kinetic energy of the electron will-
1. Increase
2. Decrease
3. remain constant
4. Need more data to say
## Answer (Detailed Solution Below)
Option 3 : remain constant
## Motion in a Magnetic Field MCQ Question 12 Detailed Solution
The correct answer is Remain constant.
CONCEPT:
• The property of matter which is responsible for electrostatic force is called an electric charge.
• Proton is a positively charged particle whereas electron is a negatively charged particle.
• The region around any magnet in which the magnetic force can be experienced by any other magnet or by any magnetic material is called a magnetic field of the magnet.
• Magnetic force on any moving charged particle
$$\Rightarrow \vec F= {\rm{}}q\vec V \times \vec B$$
Where q = charge, $$\vec V$$ = velocity vector and $$\vec B$$ = magnetic field vector
$$\vec V \times \vec B$$ is the cross product of velocity vector and magnetic field vector
EXPLANATION:
• Magnetic force on any moving charged particle
$$\Rightarrow \vec F= {\rm{}}q\vec V \times \vec B$$
• Since the magnetic force is in the direction of the cross product of velocity and magnetic field which is perpendicular to the velocity of the charged particle.
• As the magnetic force on any moving charged particle is perpendicular to the velocity of that particle. So the magnetic force never changes the magnitude of velocity. It just changes the direction of the velocity.
• As the magnitude of the velocity is equal to speed. So the speed of the electron particle remains constant in a magnetic field and thus the kinetic energy of the electron remains constant. Therefore option 3 is correct.
# An electron (mass = 9 × 10-31 kg. charge = 1.6 × 10-19 coul.) whose kinetic energy is 7.2 × 10-18 joule is moving in a circular orbit in a magnetic field of 9 × 10-5 weber/m2. The radius of the orbit is
1. 1.25 cm
2. 2.5 cm
3. 12.5 cm
4. 25.0 cm
## Answer (Detailed Solution Below)
Option 4 : 25.0 cm
## Motion in a Magnetic Field MCQ Question 13 Detailed Solution
CONCEPT:
• When a moving charged particle enters a magnetic field then path followed by the charged particle is circular if the magnetic field is perpendicular to the velocity of the particle.
• More the radius of the path followed by the particle, lesser will be the curvature, and lesser the radius, more will be curvature.
• To perform the circular motion, the required centripetal force would be provided by the magnetic force on the moving charge.
The radius of the path followed by the charged particle moving in the magnetic field is given by:
$${\text{r}} = \frac{{{\text{mv}}}}{{{\text{Bq}}}}$$
where r = radius, m = mass, v = velocity, B = strength of the magnetic field, q = charge on the particle.
• The relation between kinetic energy (KE) and the radius followed by the charged particle is given by:
$$r\; = \;\frac{{\sqrt {2m(K E)} }}{{qB}}$$
EXPLANATION:
Given - mass (m) = 9 × 10-31 kg, charge (q) = 1.6 × 10-19 C, kinetic energy (KE) = 7.2 × 10-18 J and magnetic field (B) = 9 × 10-5 weber/m2
• The radius of the orbit is given by
$$\Rightarrow r\; = \;\frac{{\sqrt {2m(K E)} }}{{qB}}$$
$$\Rightarrow r\; = \; {\frac{{\sqrt{2 \times 9 \times {{10}^{ - 31}} \times 7.2 \times {{10}^{ - 18}}}}}{{1.6 \times {{10}^{ - 19}} \times q \times {{10}^{ - 5}}}}} \; = \;0.25\;m\; = \;25\;cm$$
# A charged particle experience magnetic force in the presence of magnetic field. Which of the following statement is correct?
1. The particle is moving and magnetic field is perpendicular to the velocity.
2. The particle is moving and magnetic field is parallel to velocity.
3. The particle is stationary and magnetic field is perpendicular.
4. The particle is stationary and magnetic field is parallel.
## Answer (Detailed Solution Below)
Option 1 : The particle is moving and magnetic field is perpendicular to the velocity.
## Motion in a Magnetic Field MCQ Question 14 Detailed Solution
CONCEPT:
• When moving through a magnetic field, the charged particle experiences a force.
• This force is given by the charge times the vector product of velocity and magnetic field.
$$F = q (\vec{v}\times \vec{B})$$
where q is the charge on particle, v is perpendicular velocity and B is the magnetic field.
• Right-Hand Rule: The direction of the force on a moving charge is given by right-hand rule 1 (RHR-1): Point the thumb of the right hand in the direction of v, the fingers in the direction of B, and perpendicular to the palm points in the direction of F.
• This force is always perpendicular to the plane formed by velocity v and magnetic field B.
EXPLANATION:
• If the particle is stationary, means v = 0
• There will be no force from the formula. F = 0
• So, options 3 and 4 are incorrect.
• If the particle velocity is parallel to the magnetic field,
• $$\vec{v}\times \vec{B} = 0$$ ; F = 0
• So, option 2 is incorrect.
• The particle should have velocity perpendicular to the magnetic field so that F ≠ 0. So the correct answer will be option 1.
# On which of the following, no magnetic force will act in a magnetic field region?
1. Beam of electrons
2. Beam of protons
3. Piece of a magnet
4. charge particle at rest
## Answer (Detailed Solution Below)
Option 4 : charge particle at rest
## Motion in a Magnetic Field MCQ Question 15 Detailed Solution
The correct option is 4.
CONCEPT:
• Magnetic field (B): The region or space around a current-carrying wire or around a magnet in which magnetic force can be experienced by other magnets is called a magnetic field.
• When a moving charged particle enters a magnetic field then the path followed by the charged particle is circular if the magnetic field is perpendicular to the velocity of the particle.
• While moving through a magnetic field, the charged particle experiences a force.
• This force is given by the charge times the vector product of velocity and magnetic field.
$$F = q (\vec{v}\times \vec{B})$$
where q is the charge on particle, v is perpendicular velocity and B is the magnetic field.
EXPLANATION:
• According to the above discussion, it is clear that the magnetic force can act only on moving charge particles, magnets, and current element.
• So there will be a magnetic force on the beam of electrons and protons. Because they are moving.
• A magnetic force will also act on a piece of a magnet but not on a charged particle at rest.
For a charge particle at rest: v = 0
$$F = q (\vec{v}\times \vec{B}) = 0$$
• Thus a charge particle at rest will have no magnetic force in a magnetic field region.
# Which of the following particle will go on straight line while passing through a magnetic field?
1. electron
2. alpha particle
3. beta particle
4. neutron
## Answer (Detailed Solution Below)
Option 4 : neutron
## Motion in a Magnetic Field MCQ Question 16 Detailed Solution
CONCEPT:
• When moving through a magnetic field, the charged particle experiences a force.
• When the direction of the velocity of the charged particle is perpendicular to the magnetic field:
• Magnetic force is always perpendicular to velocity and the field by the Right-Hand Rule.
• And the particle starts to follow a curved path.
• The particle continuously follows this curved path until it forms a complete circle.
• This magnetic force works as the centripetal force.
Centripetal force (FC) = Magnetic force (FB)
q v B = mv2/R
R = mv/qB
where q is the charge on the particle, v is the velocity of it, m is the mass of the particle, B is the magnetic field in space where it circles, and R is the radius of the circle in which it moves.
EXPLANATION:
• When a charge moves through a magnetic field, it will move in a circular motion as explained above with a radius R = mv/qB
• Electron, alpha particles, and beta particles are charged particles, so they will move in a circular motion.
• Neutron is not a charged particle.
• There will be no magnetic force on the neutron.
• So, It will not move in a circular motion and will go in a straight line.
• Hence the correct answer is option 4.
# The electron, proton and the neutron are moving with velocity v. If all the three particles enter perpendicularly into the uniform magnetic field of intensity B, then which particle will have the maximum acceleration:
1. electron
2. proton
3. neutron
4. All particles will have equal acceleration
## Answer (Detailed Solution Below)
Option 1 : electron
## Motion in a Magnetic Field MCQ Question 17 Detailed Solution
CONCEPT:
• charged particle experiences a force when it moves in a magnetic field.
⇒ F = qvBsinθ
Where, F = force due to magnetic field, q = magnitude of charge, v = velocity of charge, B = magnetic field, and θ = angle between v and B
Newton's second law of motion:
• According to Newton's second law of motion, the rate of change of momentum of a body is directly proportional to the applied unbalanced force.
• The magnitude of the force is given as,
⇒ F = ma
CALCULATION:
Given θ = 90°
• Since the neutron is a chargeless particle, so neutron will not experience any force when it enters the magnetic field. Therefore the acceleration of the neutron will be zero.
• The charge and the velocity of the electron and the proton is equal, so the force experienced by both the particle when they enter into the magnetic field of intensity B is given as,
⇒ F = qvB × sin90
⇒ F = qvB
• So, the force on the electron and the proton will be equal.
• By Newton's second law the acceleration of the particle is given as,
$$\Rightarrow a=\frac{F}{m}$$
$$\Rightarrow a\propto\frac{1}{m}$$
• When force is the same, the acceleration is inversely proportional to the mass.
• We know that the mass of the proton is more than the electron, so the acceleration of the electron will be more. Hence, option 1 is correct.
# A particle of mass m, charge Q and kinetic energy T enters a transverse uniform magnetic field of induction $$\vec{B}$$. After 3 seconds the kinetic energy of the particle will be -
1. T
2. 4 T
3. 3 T
4. 2 T
Option 1 : T
## Motion in a Magnetic Field MCQ Question 18 Detailed Solution
CONCEPT:
• Magnetic Field: The field around the magnet that exerts a magnetic force on the magnetic substances is called a magnetic field.
• When a charged particle enters a region of the uniform magnetic field,
• it experiences a magnetic force which remains perpendicular to its motion due to which the particle undergoes a uniform circular motion.
• As the magnetic force remain perpendicular to the motion, work done by the magnetic force on the particle = 0
• Work done is given by the change in kinetic energy since work done is zero so is the kinetic energy.
• Change in kinetic energy of the particle is "0".
Work done (W) = Force (F).displacement (s) Cosθ
Where θ is the angle between F and s
EXPLANATION:
In the case of magnetic force,
The force acting is perpendicular to the velocity of the particle,
So θ = 90°
Work done (W) = F s cos90° = 0
• The kinetic energy of the particle will remain constant i.e. T.
The correct option is 1.
# A cyclotron is used to -
1. Accelerate protons
2. Accelerate electrons
3. Accelerate both protons and electrons
4. Accelerate neutrons
## Answer (Detailed Solution Below)
Option 1 : Accelerate protons
## Motion in a Magnetic Field MCQ Question 19 Detailed Solution
CONCEPT:
• cyclotron is a machine that is used to accelerate charged particles or ions to high energies.
• A simple cyclotron consists of a large circular magnet providing a constant magnetic field across the gap between the pole-faces.
• A charged particle is injected in the middle of the magnetic field and the particle is accelerated in the magnetic field in a circular shape.
EXPLANATION:
• Electrons cannot be accelerated in a cyclotron. A large increase in their energy increases their velocity to a very large extent. This throws the electrons out of step with the oscillating field. So option 2 and 3 are not correct.
• Thus, Cyclotron only accelerates protons and Ions to high energies. So option 1 is correct.
• Neutrons do not carry any charge with them so can’t be accelerated. So option 4 is not correct.
# A charged particle falls perpendicularly into a uniform magnetic field and traces a circular path. The relationship between radius r of the circular path and KE of the particle is given as-
1. r ∝ KE2
2. r ∝ KE-1
3. r2 ∝ KE3
4. r ∝ $$\sqrt{KE}$$
## Answer (Detailed Solution Below)
Option 4 : r ∝ $$\sqrt{KE}$$
## Motion in a Magnetic Field MCQ Question 20 Detailed Solution
The correct answer is option 4) i.e. r ∝ $$\sqrt{KE}$$
CONCEPT:
• Magnetic force: Magnetic force is the force experienced by electrically charged particles moving in a magnetic field.
• The magnitude of the magnetic force (F) on a charge (q) moving at a speed (v) in a magnetic field of strength B is given by:
$$F = qvBsin θ$$
Where θ is the angle enclosing v and B.
• Right-hand rule: The magnetic force acting on a moving charged particle is always perpendicular to the plane formed by v and B and follows the right-hand rule.
• When a charged particle moves perpendicular to the magnetic field (θ = 90), it follows a curved path and undergoes circular motion.
• Here, the magnetic force supplies the centripetal force which keeps the particle in a circular motion.
Magnetic force, $$F = qvB =\frac{mv^2}{r}$$
Where m is the mass of the particle, v is the velocity of the particle, and r is the radius of the circular path traced by the particle.
EXPLANATION:
The kinetic energy of a particle is given by $$KE = \frac{1}{2}mv^2$$
Where m is the mass and v is its velocity.
$$\Rightarrow v = \sqrt{\frac{2KE}{m}}$$ ----(1)
The magnetic force experienced by the particle$$F = \frac{mv^2}{r} = qvB$$
$$\Rightarrow r = \frac{mv}{qB}$$ ----(2)
Substituting (1) in (2),
$$\Rightarrow r = \frac{m{\sqrt{\frac{2KE}{m}}}}{qB} = \frac{\sqrt{2mKE}}{qB}$$
$$\Rightarrow r \propto \sqrt{KE}$$ | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 1, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.9604822397232056, "perplexity": 798.181499504018}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.3, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2022-21/segments/1652662625600.87/warc/CC-MAIN-20220526193923-20220526223923-00129.warc.gz"} |
http://gmatclub.com/forum/set-x-consists-of-100-numbers-the-average-arithmetic-mean-103536.html | Find all School-related info fast with the new School-Specific MBA Forum
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# Set X consists of 100 numbers. The average (arithmetic mean)
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Set X consists of 100 numbers. The average (arithmetic mean) of set X [#permalink] 30 May 2010, 05:49
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Set X consists of 100 numbers. The average (arithmetic mean) of set X is 10, and the standard deviation is 4.6. Which of the following two numbers, when added to set X, will decrease the set’s standard deviation by the greatest amount?
A. -100 and -100
B. -10 and -10
C. 0 and 0
D. 0 and 20
E. 10 and 10
[Reveal] Spoiler: OA
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Last edited by Bunuel on 24 Sep 2015, 02:52, edited 1 time in total.
Renamed the topic, edited the question and added the OA.
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Re: Set X consists of 100 numbers. The average (arithmetic mean) of set X [#permalink] 30 May 2010, 06:22
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Hussain15 wrote:
Set X consists of 100 numbers. The average (arithmetic mean) of set X is 10, and the standard deviation is 4.6. Which of the following two numbers, when added to set X, will decrease the set’s standard deviation by the greatest amount?
A. -100 & -100
B. -10 & -10
C. 0 & 0
D. 0 & 20
E. 10 & 10
Standard Deviation is deviation from the mean. If all the numbers in a set are equal to mean, then the standard deviation will be zero.
Therefore, in the given set with mean of 10, if we add 10 & 10, then the standard deviation will reduce. All other numbers will increase the standard deviation.
Please note that B is not the answer. Mean is +10 and, therefore, -10 is 20 points away from +10 (its not equal to the mean). Therefore, -10 will increase the standard deviation of the given set.
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Re: Set X consists of 100 numbers. The average (arithmetic mean) of set X [#permalink] 02 Jun 2010, 16:48
Clearly E, as the mean of the set is 10. Adding the mean as an extra value in the set will decrease the standard deviation.
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Re: Set X consists of 100 numbers. The average (arithmetic mean) of set X [#permalink] 04 Jun 2010, 02:41
I have a doubt for this explaination.
The question says "will decrease the set’s standard deviation by the GREATEST amount" Now if SD is +ve then adding a negetive number will reduce the standard deviation correct?? and if SD is -ve then adding the positive number will reduce the standard deviation. the value of the added will depend on the number of data given.
Please correct me if i am wrong.
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Re: Set X consists of 100 numbers. The average (arithmetic mean) of set X [#permalink] 04 Jun 2010, 05:04
I have another doubt:
If we will add 10 & 10 to set X, then the arithematic mean will not change i.e it will still be 10. Hence the standar deviation will not change & will remain the same. But our requirement is that SD will decrease in maximum.
What am I missing here?
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Re: Set X consists of 100 numbers. The average (arithmetic mean) of set X [#permalink] 04 Jun 2010, 05:14
Hussain15 wrote:
I have another doubt:
If we will add 10 & 10 to set X, then the arithematic mean will not change i.e it will still be 10. Hence the standar deviation will not change & will remain the same. But our requirement is that SD will decrease in maximum.
What am I missing here?
I think the red portion in my statement above is not correct. SD will come down.
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Re: Set X consists of 100 numbers. The average (arithmetic mean) of set X [#permalink] 04 Jun 2010, 05:43
Yes, this part is incorrect.
There will be no change in the average if you add (10, 10), but the difference will be zero, when we calculate for SD. So, SD will be <4.6.
E is correct, which brings the miminum sum after subtracting and squaring the differences for SD calculations.
Hussain15 wrote:
Hussain15 wrote:
I have another doubt:
If we will add 10 & 10 to set X, then the arithematic mean will not change i.e it will still be 10. Hence the standar deviation will not change & will remain the same. But our requirement is that SD will decrease in maximum.
What am I missing here?
I think the red portion in my statement above is not correct. SD will come down.
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Re: Set X consists of 100 numbers. The average (arithmetic mean) of set X [#permalink] 04 Jun 2010, 05:49
Expert's post
Hussain15 wrote:
Hussain15 wrote:
I have another doubt:
If we will add 10 & 10 to set X, then the arithematic mean will not change i.e it will still be 10. Hence the standar deviation will not change & will remain the same. But our requirement is that SD will decrease in maximum.
What am I missing here?
I think the red portion in my statement above is not correct. SD will come down.
"Standard deviation shows how much variation there is from the mean. A low standard deviation indicates that the data points tend to be very close to the mean, whereas high standard deviation indicates that the data are spread out over a large range of values."
So when we add numbers, which are far from the mean we are stretching the set making SD bigger and when we add numbers which are close to the mean we are shrinking the set making SD smaller.
According to the above adding two numbers which are closest to the mean will shrink the set most, thus decreasing SD by the greatest amount.
Closest to the mean are 10 and 10 (actually these numbers equal to the mean) thus adding them will shrink the set most, thus decreasing SD by the greatest amount.
amitjash wrote:
I have a doubt for this explaination.
The question says "will decrease the set’s standard deviation by the GREATEST amount" Now if SD is +ve then adding a negetive number will reduce the standard deviation correct?? and if SD is -ve then adding the positive number will reduce the standard deviation. the value of the added will depend on the number of data given.
Please correct me if i am wrong.
SD is always $$\geq{0}$$. SD is 0 only when the list contains all identical elements (or which is same only 1 element).
For more on this issue please check Standard Deviation chapter of Math Book (link in my signature) and the following two topics for practice:
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Re: Set X consists of 100 numbers. The average (arithmetic mean) of set X [#permalink] 04 Jun 2010, 09:48
You can prove it yourself with a couple quick calculations. Try calculating the SD for the set
{1,2,3}
and then calculate it for the set
{1,2,2,3}
Notice how it decreases.
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Set X consists of 100 numbers. The average (arithmetic mean) [#permalink] 24 Oct 2010, 13:05
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Set X consists of 100 numbers. The average (arithmetic mean) of set X is 10, and the standard deviation is 4.6. Which of the following two numbers, when added to set X, will decrease the set’s standard deviation by the greatest amount?
A. -100 and -100
B. -10 and -10
C. 0 and 0
D. 0 and 20
E. 10 and 10
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Re: Standard Devi [#permalink] 24 Oct 2010, 13:10
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shrive555 wrote:
Set X consists of 100 numbers. The average (arithmetic mean) of set X is 10, and the standard deviation is 4.6. Which of the following two numbers, when added to set X, will decrease the set’s standard deviation by the greatest amount?
A. -100 and -100
B. -10 and -10
C. 0 and 0
D. 0 and 20
E. 10 and 10
"Standard deviation shows how much variation there is from the mean. A low standard deviation indicates that the data points tend to be very close to the mean, whereas high standard deviation indicates that the data are spread out over a large range of values."
So when we add numbers, which are far from the mean we are stretching the set making SD bigger and when we add numbers which are close to the mean we are shrinking the set making SD smaller.
According to the above adding two numbers which are closest to the mean will shrink the set most, thus decreasing SD by the greatest amount.
Closest to the mean are 10 and 10 (actually these numbers equal to the mean) thus adding them will shrink the set most, thus decreasing SD by the greatest amount.
For more on this issue please check Standard Deviation chapter of Math Book (link in my signature) and the following two topics for practice:
Hope it helps.
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Re: Set X consists of 100 numbers. The average (arithmetic mean) [#permalink] 08 Dec 2013, 23:33
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Bunuel wrote:
gmatgambler wrote:
Set X consists of 100 numbers. The average (arithmetic mean) of set X is 10, and the standard deviation is 4.6. Which of the following two numbers, when added to set X, will decrease the set’s standard deviation by the greatest amount?
A)-100 and -100
B)-10 and -10
C)0 and 0
D)0 and 20
E)10 and 10
Merging similar topics. Please refer to the solutions above.
Theory on Statistics and Sets problems: math-standard-deviation-87905.html
All DS Statistics and Sets problems to practice: search.php?search_id=tag&tag_id=34
All PS Statistics and Sets problems to practice: search.php?search_id=tag&tag_id=55
Similar questions to practice:
a-certain-list-has-an-average-of-6-and-a-standard-deviation-97473.html
a-certain-list-of-100-data-has-an-average-arithmetic-mean-87743.html
a-certain-list-of-200-test-scores-has-an-average-131448.html
new-ds-set-150653-60.html#p1211907
Hope this helps.
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Re: Set X consists of 100 numbers. The average (arithmetic mean) [#permalink] 14 Jun 2014, 04:51
How I think about problems associated with means and standard deviations is with scattered data points. Since this question is regarding standard deviations (and how to reduce it), a quantity calculated to indicate the extent of deviation for the group -- the greater the deviation from the mean the greater the standard deviation. Therefore what data points will help to reduce deviation from the mean of set X [10]. If you add two points with the value of the mean their deviation will be 0, which is the smallest deviation you can add to the set of numbers.
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Re: Set X consists of 100 numbers. The average (arithmetic mean) of set X [#permalink] 24 Sep 2015, 01:33
i reviewed math of Gmat club and found that 10,10 will not decrease the SD
Re: Set X consists of 100 numbers. The average (arithmetic mean) of set X [#permalink] 24 Sep 2015, 01:33
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http://mathhelpforum.com/pre-calculus/83889-solving-exponential-simultaneous-equations.html | Math Help - Solving exponential simultaneous equations
1. Solving exponential simultaneous equations
The actual problem shows a graph however I can state all the information. The graph is of a sinusiodal waveform where the amplitude is decaying exponentially. The formula for the graph is given by the equation:
T = Ae^-Ktsin(wt + ø)
The question is to find A,K,w and ø
Being quite confident in sinusoidal waveforms I can tell you that:
w = 40 x pi or 125.66 (whichever tickles your fancy)
ø = -1.885
However im stuck with the A and K.
Assuming that the maximum peaks occur when sin(wt + ø) = 1 then:
0.23 = Ae^-K0.0275
0.08 = Ae^-K0.0775
I now have 2 points to solve simultaneously for A and K.
Heres my attempt:
0.23/0.08 = Ae^-K0.0275/Ae^-K0.0775
2.875 = e^-K0.5
K = (1/0.5) x ln(2.875) = 2.1121
When you plug this back into the two equations however you get two different answers for A and A is supposed to be a constant!! Can anyone see where im going wrong here?
Thanks in advance for any help.
2. Hi
0.23/0.08 = Ae^-K0.0275/Ae^-K0.0775
2.875 = e^K0.05
K = (1/0.05) x ln(2.875) = 21.121
3. oops LOL. Thats typical me that is. Do all the hard work then miss out a zero or put in the wrong sign convention. lol. cheers. | {"extraction_info": {"found_math": false, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.8076895475387573, "perplexity": 2227.3136950105018}, "config": {"markdown_headings": false, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2015-18/segments/1430460160413.1/warc/CC-MAIN-20150501060240-00090-ip-10-235-10-82.ec2.internal.warc.gz"} |
http://blog.nguyenvq.com/blog/tag/rmpi/ | ## Scheduled Parallel Computing with R: R + Rmpi + OpenMPI + Sun Grid Engine (SGE)
Recently I’ve learned how to do parallel computing in R on a cluster of machines thanks to the R packages snowfall, snow, and Rmpi. I’ve been using the SOCKET method with snowfall since together they make things simple. With these tools, I can reduce day/week long jobs to hours or a day across many (100) cores/cpus.
However, system admins would prefer me to do things using the sun grid engine (sge) or one of their job scheduler since clusters are usually a shared resource and having “rogue” jobs like mine that hog all the resources aren’t really a good thing. Aside from scheduling jobs, another great thing about SGE is that it determines which nodes to use (idle?) with R so I don’t have to determine the list of nodes.
Luckily, people have attacked this problem already. First, Revolutions Computing has an internal document that gives instructions on how to install R, Rmpi, OpenMPI, and SGE to get them to work together. If you email them and ask for it, they are more than willing to share it. The document is “sge-snow.pdf.” After things are installed, here is how to get things to work.
### Rmpi with OpenMPI and SGE via qsub:
First, copy the content of Rprofile that is packaged in Rmpi into ~/.Rprofile. Place the following in a shell script to be submitted by qsub (an example script is at the end):
mpirun -np 51 R --no-save -q < SGEtest.R > SGEtest.Rout
NOTE: 51 is the number of cores/cpus to use, 1 master + 50 slaves. Inside the R script, do not use anything that belongs to snow or snowfall. Just use Rmpi’s functions. Also, by using mpirun, we do NOT need to spawn slaves as they are spawned in the mpirun command. We also do not need to call library(Rmpi). Put the following in the R script (SGEtest.R) to see that things are running:
mpi.remote.exec(paste("I am",mpi.comm.rank(),"of",mpi.comm.size()))
mpi.remote.exec(paste("I am",Sys.info(),"of",mpi.comm.size()))
### snow with OpenMPI and SGE via qsub:
First, place the location of the executable RMPISNOW from the snow package in the PATH variable (or use the direct location wherever you see RMPISNOW in the command line). DO NOT put the Rprofile from Rmpi into ~/.Rprofile. Place the following in the shell script to be submitted by qsub:
mpirun -np 21 RMPISNOW < SGEtest2.R > SGEtest2.Rout
In the R script, use only snow functions (not Rmpi or snowfall). No need to call library(snow). Put the following in the R script (SGEtest2.R) to test:
cl <- makeCluster()
print(clusterCall(cl, function() Sys.info()))
### snow with OpenMPI and SGE via qrsh (interactive)
Similar to 2, but run
qrsh -V -q int64 mpirun -np 9 RMPISNOW
instead of the qsub command to get an interactive session.
### Sample script for SGE
For the first two cases, a sample openMPI_R.sh script is:
#!/bin/bash
# here's the SGE directives
# ------------------------------------------
#$-q longbat-adc # <- the name of the Q you want to submit to #$ -pe openmpi 51 # <- load the openmpi parallel env w/ 4 slots
#$-S /bin/bash # <- run the job under bash #$ -N MPI-SGE # <- name of the job in the qstat output
#$-o MPI-SGE.out # <- name of the output file. #$ -e MPI-SGE.stderr # <- name of the stderr file.
echo "calling mpirun now"
## mpirun -np 51 R --no-save -q < SGEtest.R > SGEtest.Rout
mpirun -np 21 RMPISNOW < SGEtest2.R > SGEtest2.Rout
## call via: qsub openMPI_R.sh
Finally, I would like to point out that currently snowfall does not yet work with SGE because it requires a call to sfInit(), and this conflicts with the cluster called from mpirun. This made me learn some functions from snow, which aren’t all that much different from snowfall.
Also, there is an rsge package for R that seems to work too.
### UPDATE 1/25/2010
1. We don’t need to specify -np 51 in the mpirun command. If we omit it, SGE passes this information directly to OpenMPI.
2. I tried installing this myself. A few things to note are: a. compile OpenMPI with the –with-sge flag. b. Place the bin directory of OpenMPI in PATH if it is installed in a non-standard placed. Also, remember to place the directory where RMPISNOW resides into PATH as well. c. install Rmpi: R CMD INSTALL Rmpi_0.5-8.tar.gz –lib=~/Rlib –configure-args=”–with-mpi=/home/vqnguyen/openmpi-1.4.1-vqn/” OR specify MPI_ROOT environment variable as home/vqnguyen/openmpi-1.4.1-vqn. d. Place “export LD_LIBRARY_PATH=/path/to/libmpifolder:$LD_LIBRARY_PATH” in .bashrc if the variable does not include it. This is required for library(Rmpi) to work. Also place “.libPaths(“~/Rlib”)” in RMPISNOWprofile in order to see where my Rmpi is. e. Set up a parallel environment in SGE either with qmon or on the command line with: $ qconf -Ap openmpi.config where the config file is as follow:
openmpi configuration:
===============================
pe_name openmpi
slots 666
user_lists arusers
xuser_lists NONE
start_proc_args /bin/true
stop_proc_args /bin/true
allocation_rule \$round_robin
control_slaves TRUE
urgency_slots min
accounting_summary TRUE
===============================
You can name the PE anything and set the number slots. Make sure the user list has you in it. Also, make sure you add the Q’s u want to work with into this PE.
1. specifying an outfile in the makeCluster() command in RMPISNOW doesn’t do anything since the cluster is called at the RMPISNOW’s invocation. If we look at the RMPISNOWprofile, we see that the output is sink to /dev/null. I tried a few ways to get the workers’ output out, via sink() on each worker via clusterEvalQ or setting the OUT or R_SNOW_OUTFILE variables (see RMPInode.R and RMPInode.sh). How I got it to work was with:
clusterEvalQ(cl, sinkWorkerOutput("nodes.out"))
1. Of course, make sure u have passwordless ssh on. If you have host key messages (ie, type yes to accept key) and your job doesnt run, put
StrictHostKeyChecking no | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 1, "mathjax_display_tex": 0, "mathjax_asciimath": 1, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.46093156933784485, "perplexity": 6614.800962648999}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2019-26/segments/1560627997731.69/warc/CC-MAIN-20190616042701-20190616064701-00473.warc.gz"} |
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Question from david: hi how many concrete blocks would i need for an extension 50 ft long ,20 ft wide and 12ft height
Hi David,
The concrete blocks that form one of the walls in my office measure 16 inches by 8 inches so each one covers an area of $16 \times 8 = 128$ square inches.
The 50 foot long by 12 foot high wall you want to construct is $50 \times 12 = 600$ inches by $12 \times 12 = 144$ inches so its area is $600 \times 144$ square inches. Thus the number of blocks you need for this wall is
$\frac{600 \times 144}{128}.$
Perform the analogous calculation for the 20 foot walls and total the number of blocks you obtain. You will need to add a few extra as there will be some cutting and wastage at the corners.
Penny
Math Central is supported by the University of Regina and The Pacific Institute for the Mathematical Sciences. | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 2, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.6737061738967896, "perplexity": 608.8208169712318}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2019-13/segments/1552912202326.46/warc/CC-MAIN-20190320105319-20190320131319-00224.warc.gz"} |
https://de.maplesoft.com/support/help/view.aspx?path=StudyGuides%2FMultivariateCalculus%2FChapter1%2FExamples%2FSection1-5%2FExample1-5-1 | Example 1-5-1 - Maple Help
Chapter 1: Vectors, Lines and Planes
Section 1.5: Applications of Vector Products
Example 1.5.1
If , , and ,
a) Compute $\left[\mathbf{ABC}\right]$, the Triple Scalar (or Box) Product $\mathbf{A}·\mathbf{B}×\mathbf{C}$.
b) Verify the identity $\mathbf{A}·\mathbf{B}×\mathbf{C}=\mathbf{A}×\mathbf{B}·\mathbf{C}$ for the Triple Scalar Product.
For more information on Maplesoft products and services, visit www.maplesoft.com | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 103, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.8377891778945923, "perplexity": 7739.71778253382}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.3, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2023-14/segments/1679296943698.79/warc/CC-MAIN-20230321131205-20230321161205-00070.warc.gz"} |
https://www.lessonplanet.com/teachers/what-is-the-formula-for-the-nth-term-in-a-geometric-sequence | # What is the Formula for the nth Term in a Geometric Sequence?
What is the difference between an arithematic sequence and a geometric sequence? In an arithematic sequence the constant ratio is added, and in a geometric sequence the constant ratio is multiplied. Watch this video and learn how to use a formula to find the nth term in a geometric sequence.
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## lgbasallote 3 years ago What is the converse of the implication "If |x| = x, then x >= 0" Delete Cancel Submit
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1. lgbasallote
• 3 years ago
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it would be if x > =0 then |x| = x yes?
• 3 years ago
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if $\left| x \right|=x,then x <, 0$
3. lgbasallote
• 3 years ago
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isn't that inverse?
4. lgbasallote
• 3 years ago
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wait..no...it isn't...
5. lgbasallote
• 3 years ago
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i don't know what kind of statement that is...
6. lgbasallote
• 3 years ago
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if p then not q
7. PhoenixFire
• 3 years ago
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No, @lgbasallote is right. $P \rightarrow Q$ converse is $Q \rightarrow P$
8. lgbasallote
• 3 years ago
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wonderful
• 3 years ago
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excuse me ,sorry for the confusion
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Thanks for being so helpful in mathematics. If you are getting quality help, make sure you spread the word about OpenStudy. | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 1, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.9998613595962524, "perplexity": 15156.710073351713}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2015-48/segments/1448398461132.22/warc/CC-MAIN-20151124205421-00014-ip-10-71-132-137.ec2.internal.warc.gz"} |
http://mathoverflow.net/questions/87669/psi-class-in-overlinem-0-n?sort=newest | # $\psi$ class in $\overline{M}_{0,n}$
Basic question, but I found no reference.
Is the $\psi$ class the only one which is not a boundary class in the PIcard group of the Deligne-Mumford compactification of $\mathcal{M}_{0,n}$? Or can it be expressed in terms of boundary divisors? If yes what is its expression?
-
Unless you mean something else when you write $\psi$ class, it is expressible in terms of boundary divisors.
That is, if $\psi_i$ is the $i$-th cotangent bundle, then you can write it in terms of boundary divisors. One reference for this is the tome "Mirror Symmetry" by Hori, Katz, Klemm, et al. on p. 513, the comparison lemma.
The idea is that you can consider the forgetful maps $\pi$ from $M_{0,n}$ to $M_{0,n-1}$ and look at the divisor $$\psi_i - \pi^*\psi_i$$ (where the $\psi$ classes are, by abuse of notation, living on different spaces). This is expressible in terms of boundary divisors, and so we can inductively write out the $\psi$ classes on any $M_{0,n}$. | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 1, "mathjax_display_tex": 1, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.9509677290916443, "perplexity": 148.55434693222296}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 20, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2015-40/segments/1443736676381.33/warc/CC-MAIN-20151001215756-00141-ip-10-137-6-227.ec2.internal.warc.gz"} |