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Part of the
The IMA Volumes in Mathematics and its Applications
book series (IMA, volume 108)
Molecular similarity aims to give a quantitative answer to the question of how similar two given molecules are. Such indices are of use in drug design as aids to the creation of molecular mimics and in structure-activity studies or measures of molecular diversity. Similarity is most often computed in terms of molecular shape or electrostatic potential.
The advent of combinatorial techniques and the use of high throughput synthesis have created a need for ever faster methods of computation. Numerical calculation has been superceded by analytical evaluation of integrals, but even faster methods are urgently needed. This is especially so if we can ever hope to take thousands of molecules and calculate the similarity between all pairs.
A promising technique is to use two-dimensional molecular representations and to utilise methodologies perfected in optical character recognition.
KeywordsCentral Moment Optical Character Recognition Quantitative Structure Activity Relation Molecular Similarity Comparative Molecular Field Analysis
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.
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Visit "Leo the Gecko" while he stalks crickets. Compliments of Jen Germano, Western student (Quicktime movie)
The ‘rainforest’ of the ocean, coral reefs, also requires a constant input of atmospheric CO2. The coral reefs utilize carbonate chemistry in saline water which creates the molecule CaCO3, calcium carbonate (the same basic molecule as human bone). This molecule creates the structure to the reef and the colors associated with reefs are the organismal tissue over that structure. The color of coral reefs, or more precisely coral polyp tissues, is from a symbiotic relationship with a single-celled microalgae (plant) named zooxanthellae. This plant lives within the corals’ tissue and gives the colony food from photosynthesis as well as tissue color. In turn the nutrient ‘wastes’ from coral polyps benefit the microalgae. It is this relationship that makes the building of coral reefs possible. The relationship is responsible for the distribution of coral reef around the world (Figure 1.).
FIGURE 1: ( http://en.wikipedia.org/wiki/Image:Coral_reef_locations.jpg )
(Red dots indicate a coral reef)
Coral reefs offer an incredible value to society as they provide medicine, fish nurseries, coastal protection, food and many other benefits. The coral reef ecosystem is exceptionally complex and not fully understood. Just as rainforests produce a limited conversion of CO2, so do coral reefs. The remaining CO2 begins to change environmental conditions. To fully appreciate the effects of changing chemical, biological and geological processes on coral reefs in the environments in which they live, we need to examine each of these processes to understand how each may contribute to the success or failure of coral reefs.
We will first consider the broader environmental changes when looking at coral reef ecosystems. As our human population increases the manipulation of the global environment is a constant concern. Climatic and environmental “change” can also be termed as a “stress.” Logging trees allows greater sediment/soil run-off into coastal waters, artificial fertilizers accelerating aquatic phosphorus and nitrogen cycles, and sewage piped into the ocean causing eutrophication are just a few examples of the environmental changes.
Environmental changes are also responsible for the shift in reef carbon budgets (Kleypas, 2000). If the coral reefs need the balanced atmospheric/aqueous CO2 interface, by definition an unbalanced interface may affect coral reefs, Figure 2. For instance, as atmospheric CO2 enters the ocean it quickly dissociates and becomes one of three chemical species; H2CO3, HCO3- and CO32-, Figure 3. The dominant or most abundant species depends on the amount of CO2 present at the interface and existing aqueous conditions such as pH. At present, the marine environmental conditions make HCO3- the dominant species, making the much valued CO32- a growth limiting variable for coral reefs.
FIGURE 2 (Kleypas, National Center for Atmospheric Research)
With CO32-, the dissolved cations in the water, namely Ca2+ combine and the coral reef has its resource to grow. Unfortunately, the increase of CO2 today, is pushing the chemical equilibrium further towards the HCO3- chemical species, making CO32- less available, and coral are either slowing in growth and/or losing density/dissolving (like osteoporosis). The result in the chemical species change is that the ocean environment is becoming more acidic (termed ocean acidification) creating an additional environmental stress, Figure 3 calculation table.
FIGURE 3 (Kleypas, National Center for Atmospheric Research)
Stress is further subdivided into acute and chronic stresses (Table 1). An acute stress is short-term usually causing rapid damage, such as a hurricane. A chronic stress takes place over longer periods of time and is usually associated with a more gradual influence on the environment. The most devastating combination is an already chronically stressed reef (i.e. suffering from ocean acidification) suddenly suffering an acute stress (i.e. hurricane), where reef survival or recovery after the acute stress becomes much more bleak as larger percentage of the reef is damaged. Combinations of factors are most likely what is happening to species such as, Acropora in the Caribbean and around Florida. This “species have suffered a 97% decline in areas off the Florida Keys and the in the Caribbean since 1985.” (Sainz, 2006) The National Oceanic and Atmospheric Administration (NOAA) has recently made great contributions to positive legislation in coral reef protection as deeming the Acropora a threatened species, under the Endangered Species Act. (Sainz, 2006)
The NOAA stated, “If these losses are not arrested and reversed, Florida’s corals could go extinct within the foreseeable future, resulting not only in the loss of these irreplaceable forms of life, but also billions of dollars in tourist, recreational, medicinal, and subsistence income.” Acropora is suffering more than one chronic stress and when large hurricanes travel into coastal waters, the coral are easily damaged and recovery is a much greater challenge.
TABLE 1 (Kleypas, National Center for Atmospheric Research)
Chronic Stresses Global Regional Local Comments
Carbonate ion decrease and reduced calcification X Cooler areas will be stressed first, opposing possible warming benefit
Temperature increase X Gradual increase may be chronic stress in warm areas, benefit in cool
Over harvesting X X X Fishing, commercial, recreational, souvenir and trade
Nutrient Loading X X Land use, agriculture, sewage treatment, burning and increased run-off
Introduced/invasive Species/Disease X Increased competition and debilitation by parasites, predators or disease
Ocean/Atmospheric circulation change X Specific predictions are difficult
Coastal and watershed alteration X X Alteration of circulation patterns, run-off and land-ocean coupling
Sedimentation X X Land use for agriculture, land clearing, construction, increased erosion and run-off
Temperature increases X X Transient high-temperature episodes are major stresses
Intensified climate change X X Linkage to climate change uncertain, major factor in acute temperature stress
Diseases; introduced or invasive species X X
Storm frequency and intensity increases X X Increased virulence and frequency of disease outbreaks may be linked to climate change
Sedimentation X X Land use for agriculture, land clearing, construction, increased erosion and run-off
Urbanization, watershed modification X X Increase in waste, other discharges into the environment, alteration of land-ocean coupling
Commercial and incidental destruction X X Transportation, tourism and recreational use, mining, dredging, destructive fishing
Other stresses can be seen in Figure 4.
Coastal zone modification and mining of coral reefs are stresses directly attributed to humankind. A classic example would be the modification of the Florida Keys, the third largest coral reef tract in the world (EPA online). The Florida Keys, with bridges now attaching once separate islands, have resulted in waterways being redirected and human pollutants being introduced…greatly impacting these coral reefs over the last several decades. These modifications to the marine environment in conjunction with, “relentlessly growing human populations…poor water quality from land-based sources including sewage, fertilizers, and sedimentation; over-fishing; and global climate change,” may have changed the coral reefs surrounding Florida indefinitely (Ogden and Miller, 2001). Another attack to coral reefs by human influences occur when building supplies for industry and resident homes are in low supply and reefs are used for construction materials.
Invasive marine species are often introduced into coastal environments by the massive trades of goods from port-to-port around the world. “Accidentally introduced into Tampa Bay (U.S.A.) in the Gulf of Mexico in 1999, the green mussel (Perna viridis), a native to the Indo-Pacific region, has proliferated and dispersed southwards along peninsular Florida.
FIGURE 4: http://maps.grida.no/go/graphic/reefs_at_risk_major_observed_threats_to_the_world_s_coral_reefs
During 2002 another introduction of P. viridis occurred on the northeast coast of Florida and larval dispersal has also carried the species northward in Atlantic coastal waters.” (Powers et al., 2004) These invasive species are disruptors to a balanced and seemingly fragile ecosystem, when they out compete endemic organisms for resources. The major concerns for coral reefs are the introduced diseases or parasites from other parts of the world that produce additional stresses. And, as Dr. Harvell wrote in 2002, “changes in El NiĖo-Southern Oscillation events have had a detectable influence on marine and terrestrial pathogens, including coral diseases, oyster pathogens…” The bacterial diseases of concern for Caribbean coral are called, “black-band disease and white-band disease.” (Patterson, et al., 2002) With in introduction of invasive species, climatic changes can create more inhospitable environments to reproduce, resulting in greater short-term and long-term damages.
Coral reefs also have predators. The crown-of-thorns starfish is a powerful biological stress and like a sickness has population explosions or outbreaks when large numbers of them attack a coral reef simultaneously. The crown-of-thorns starfish moves over live coral colonies and inverts its stomach onto the coral tissue, releasing digestive enzymes, and sucks up the dissolving coral tissues. It is thought that a decrease in crown-of-thorn starfish predators from over fishing and increased anthropogenic nutrients in the marine environment have created an epidemic-like population of the species.
El NiĖo is often connected to global warming and remains complex in its far reaching effects. El NiĖo essentially transfers the world-wide heat or energy budget into shifting areas of climatic extremes. For instance, winds created by El NiĖo can cause water to be about 2 feet higher in Indonesia than Ecuador (NOAA online). The changes in water depth, along with heat and wind can also change the water column stratification either creating colder water or warmer water at abnormal depths depending where on earth the phenomenon is being observed. The warmer waters tend to collect in latitudinal areas directly effecting coral reefs communities, increasing sea surface temperature. Storms are also created by El NiĖo, but are usually more intense and severe. The reference to the, El NiĖo-Southern Oscillation, takes into consideration the variable of climate change in addition to a list of other stresses. In work done by Dr. Peter W. Glynn, he showed wide-spread coral bleaching in direct relationship with the El NiĖo events in 1982-1983, 1987-1988 and in 1997-1998.
Coral bleaching viewed as a combination of stresses (chronic, acute and/or climatic) results in discoloration/whitening of the coral reefs. Bleaching is the expulsion of zooxanthellae from the coral tissue, which is naturally translucent, and the calcium carbonate structure can be seen underneath. Coral reefs have “bleached” for centuries for natural adaptation. The cycle is to remove zooxanthellae of the symbiotic relationship when conditions are physiologically taxing, and re-absorb the zooxanthellae when conditions return to normal, or more tolerant zooxanthellae are found. If the zooxanthellae do not return to the coral tissue, coral reefs most often die. Specific factors also causing bleaching are: high and low temperatures, intense light and salinity change. Coral bleaching is further defined into three types of bleaching 1) animal-stress bleaching, 2) algal-stress bleaching and 3) physiological bleaching (Fitt et al, 2001). Extremely problematic coral reef bleaching events occur when a large percentage of the overall coral reef population bleaches; mortality is high, and the recovery growth of the remaining species remaining is naturally slow.
It is thought that in approximately thirty years we could see the complete extinction of coral reefs around the world (IMAX film quote, “Coral Reef”). The projected model by Dr. Kleypas shows that as sea surface temperature (SST) increases with increased atmospheric CO2 the available building blocks of coral reef, CO32-, continually decrease, Figure 5.
To further explain the effect of ocean acidification on carbonate species, as they relate to coral reefs, Figure 7 illustrates that as pH changes the availability of the three carbonate species changes. The mean pH of the ocean is approximately 8.3. As pH becomes more acidic Figure 7 shows that the CO32- decreases in availability and of HCO3- increases. If we model a monoprotic acid in water, water compromises the following species: H2O, H3O+, H+ and OH-. The increasing acidity makes it chemically inefficient to subtract an H+ from HCO3- than it does to add H+ to HCO3- (the characteristic of decreasing pH is the greater concentration of H+), Figure 8 (Honeyman, Colorado School of Mines). The addition of H+ to HCO3- is carbonic acid, H2CO3, Figure 6.
The future impacts of increased sea surface temperatures and a lower availability of CO32- are almost certainly going to have a negative affect on coral reefs over the next 30 years. A widely accepted prediction is, “a doubling of the pre-industrial pCO2 by the year 2065.” (Kleypas et al, 2000) The ocean temperatures will also increase, but rhe exact increments can not be accurately determined. There is a theory that global warming will create the potential for coral reefs to live at higher latitudes assuming, “a 2°C warming of SST and (assuming) that reef growth is limited to depths where irradiance was 200-300 Ķmol m-2 / s. The pole-ward shift in the 18°C isotherm resulted in a 2.5-3.5% increase in potential reef habitat area. This does not account for loss of habitat due to too-warm temperatures, and assumes that reduced light at higher latitudes is not a factor in reef development” (Kleypas et al, 2000).
Gattuso et al. 1999, continues to state that the same doubling affects will result in a decrease at an estimate of 30% of available CO32- in tropical regions. Again the result of decreased chemical availability for structure building molecules will most likely result in a decrease of coral reefs in tropical areas. A number Kleypas et al, 2000 predicts at about a 14-30% decrease in reef calcification and “those reefs which already have a low surplus of carbonate production will become non-reef coral communities.”
To look one of the United States’ most valuable coral reef ecosystems, the Florida Keys, which extends from Miami to the Dry Tortugas are included in the Florida Keys National Marine Sanctuary (FKNMS), and the Biscayne and Dry Tortugas National Parks. The FKNMS covers an area approximately, “9850 km2 with 1400 km2 of coral reef and hard bottom habitat” (Australian Institute of Marine Science, Status of Coral Reefs of the World: 2004). According to this report, the Caribbean possesses some of the best documented reef ecosystems in the world and consist of a species diversity of 64 hard coral species, 2 fire corals, and 55 octocoral species. It is to be noted that in this sanctuary the diseased stony coral has, “increased alarmingly from 20 stations in 1996 to 95 stations in 2003…a disease outbreak in 2003 affected (Acropora) corals and prompted Sanctuary management to close (affected areas)…” (Australian Institute of Marine Science. Status of Coral Reefs of the World: 2004). Not to harp on conditions too much, but poor water quality and pollution from fertilizers, sediments and other nutrients from Florida still remain considerable threats to the coral reef ecosystem. In response, the FKNMS increased water sampling everywhere including the mangrove estuaries.
Over-fishing remains a constant problem in the Florida Keys, showing 65% of the 35 fish species examined were over-fished (Australian Institute of Marine Science. Status of Coral Reefs of the World: 2004). In addition, “400-600 vessels have run aground each year in the FKNMS…damage also occurs from anchors and chains…fiber optic cables, gas pipelines…drilling and trenching” (Australian Institute of Marine Science. Status of Coral Reefs of the World: 2004). The same 2004 report states that there are considerable problems with nutrient loading (sewage) causing algal blooms, cyanobacteria, increased bioerosion rates (possibly linked to coral diseases), and increased problems with nitrogen and phosphorus from agriculture.
The brighter side of identifying all of the problematic factors in deteriorating coral reef health is the possibility of enacting social change and potential legislation to preserve coral reefs as a valuable resource. The Florida Keys now prohibits, “oil exploration, mining, large shipping traffic, anchoring on or touching corals, and collecting coral of ‘live rock’ in the Sanctuary” (Australian Institute of Marine Science. Status of Coral Reefs of the World: 2004). Referring in part back to the invasive species portion of this paper, and considering other pollutants, ships are no longer permitted to ‘discharge’ vessel water (i.e. tankers ballast water and cruise line wastewater, both of which could carry invasive organisms) inside of a specified boundary from the coast. Depending upon the area of Florida’s coral reefs, no fishing zones have been designated and the Tortugas Ecological Reserve was designated inside of the FKNMS; totaling a protective area for coral reef to about 10% of the entire sanctuary area.
A partnership between the FKNMS, the National Oceanic and Atmospheric Administration (NOAA), and the State of Florida Department of Environmental Protection (FDEP) to focus each organization’s respective talents in four areas:
(Australian Institute of Marine Science. Status of Coral Reefs of the World: 2004)
Land-Based Sources of Pollution
Fishing, Diving and Other Uses
Awareness and Appreciation, and
Maritime Industry and Coastal Construction Impacts
Under current U.S. national environmental law the National Pollution Discharge Elimination System (NPDES) controls ‘point source’ release of pollutants into State waters. Fishing is regulated by the, Florida Fish and Wildlife Conservation Commission, locally, and by the South Atlantic and Gulf of Mexico Fishery Management Councils, internationally. There are protective systems in place and without public and governmental support, coral reefs could be much worse off. But, they could also be better.
In considering all of the wonders of coral reefs as an organism and as an ecosystem, our lives would be dramatically changed if they were lost forever. Environmental transformations, whether chemical, biological, geological or any combination therein are often difficult to study, but the reality is that changes, good or bad, are taking place on a global scale. As global temperatures increase, concerns of the potential consequences fuel scientific exploration and action. Our time to find solutions in now as this responsibility falls to the talents and hard work of many in the next few decades. It is hopeful that governments are recognizing that action must be taken to protect coral reefs in this time of change. Whether it is in Indonesia trying to curtail dynamite fishing or in the United States controlling sewage dumping, social awareness is slowly turning into social responsibility. We all have a stake in preserving coral reefs, and it is conceivable that our actions, or lack there of, can be the determining factor in the health of the oceans, the health of our coastal communities and the existence of coral reefs as we have know them for centuries.
Australian Institute of Marine Science. Status of Coral Reefs of the World: 2004; Status of Coral Reefs in the U.S. Caribbean and Gulf of Mexico: Florida, Flower Garden Banks, Puerto Rico, U.S. Virgin Islands, Navassa. Edited by Clive Wilkinson. Volume 2, Section 16, pgs 1-20
EPA (online) Climate Change, Wildlife and Wildlands: Case Study – Everglades and South Florida. http://yosemite.epa.gov/OAR/globalwarming.nsf/content/ImpactsCoastalZonesSouthFlorida.html
Fitt, William K., B. E. Brown, M. E. Warner, and R. P. Dunne. 2001. Coral bleaching: interpretation of thermal tolerance limits and thermal thresholds in tropical corals. Coral Reefs 20: 51-65
Gattuso JP, Allemand D, Frankignoulle M (1999) Interactions between the carbon and carbonate cycles at organism and community levels in coral reefs: a review on processes and control by the carbonate chemistry. Am Zool 39:160-183
Harvell CD, Mitchell CE, Ward JR, Altizer S, Dobson AP, Ostfeld RS, Samuel MD. Climate warming and disease risks for terrestrial and marine biota. Science. 2002; 296(5576):2158-62 (ISSN: 1095-9203)
Honeyman B (2006) Environmental Aqeuous Chemistry course, Colorado School of Mines, Spring 2006.
Hughes TP, Baird AH, Bellwood DR, Card M, Connolly SR, Folke C, Grosberg R, Hoegh-Guldberg O, Jackson JBC, Kleypas J, Lough JM, Marshall P, Nyström M, Paulumbi SR, Pandolfi JM, Rosen B, Roughgarden J (2003) Climate Change, Human Impacts, and the Resilience of Coral Reefs. Science. 301:929-933
Kleypas JA, Buddemeier RW (2000) The Future of Coral Reefs in an Age of Global Change. Internation Journal of Earth Sciences. 90:426-437
Ogden JC and Miller SL (2006) Decline of Florida’s reefs is not a mystery. Submitted to the Miami Herald.
Precht WF and Aronson RB (2004) Climate flickers and range shifts of reef corals. The Ecological Society of America. 2(6): 307-314
Sainz, A (2006) Coral species put on ‘threatened’ list. Assoicated writer, Miami Herald, May 5, 2006
Sarmiento JL, Slater R, Barber R, Bopp L, Doney SC, Hirst AC, Kleypas J, Matear R, Mikolajewicz U, Monfay P, Soldatov V, Spall SA, Stouffer R (2004) Response of Ocean Ecosystems to Climate Warming. Global Biogeochemical Cycles. 18:1-23
Shwartz M (2006) Marine Scientists Look to the Bahamas as a Model for Coral Reef Conservation. The Stanford Report.
Williams FP and Aronson RB (2004) Climate Flickers and Range Shifts of Reef Corals. The Ecological Society of America. 2(6):307-314
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Scientists at the Technische Universität Darmstadt, Ludwig Maximilians University (LMU) Munich and the Leibniz Institute for Molecular Pharmacology (FMP) have managed to introduce tiny antibodies into living cells. The researchers now report on the synthesis and applications for these nanobodies in "Nature Chemistry".
Antibodies are one of the main weapons of our immune system. They dock to viruses, bacteria and other invaders that course through our blood, and thereby render them harmless. Antibodies also play a key role in the diagnosis and treatment of diseases and in research.
"One clear limitation is that due to their size and various other factors, antibodies are unable to permeate living cells," emphasises M. Cristina Cardoso, Professor of Cell Biology and Epigenetics in the Department of Biology at the TU Darmstadt.
Working in close collaboration with the research group led by Christian P. R. Hackenberger at the FMP Berlin, Professor of Chemical Biology at the Humboldt University of Berlin, the inter-disciplinary team has now, for the first time, managed to permeate living cells with small antibodies, also called nanobodies, and observe them microscopically. Medicine has extremely high hopes for these tiny antibodies. Although they do not occur in the human body, they have been found in camels and in cartilaginous fish.
"In order to open up the path into the cell for the nanobodies, we decorated them chemically with cyclic cell-permeating peptides that effectively act as keys to the direct permeation through the cell membrane into the cells," explains Christian Hackenberger. As the researchers report in the current issue of the renowned scientific journal "Nature Chemistry", the key peptides are either coupled stably to the nanobodies or, more loosely, so that the connection is dissolved on the inside of the cell.
The scientists successfully permeated living mouse and human cells with nanoantibodies, and examined their benefits. Cell-permeable nanobodies are suited both to the recognition and manipulation of antigens and to the analysis of protein-protein interactions. The researchers were able to observe the interaction between the tumour inhibitor p53 and its counterpart, protein HDM2, using the nanobodies and special fluorescent markings. This interaction plays an important part in the development of cancer.
Nanobodies are also highly promising medically because they are able to transport proteins to living cells. The symptoms of Rett syndrome, for instance, a genetic disease with aspects of autism, could possibly be reduced by the protein Mecp2. The researchers permeated mouse cells with Mecp2 bound to nanobodies, and were able to prove that the protein was still intact and it reached its target in the cell.
According to the report in "Nature Chemistry", the cell-permeable nanobodies are general tools that deliver therapeutically relevant proteins into living cells. This opens up a new door to treatments for diseases that have so far been untreatable.
The work by the researchers from Darmstadt, Berlin and Munich was made possible by the DFG priority programme 1623, which deals with the synthesis of functionalized proteins.
“Cell-permeable nanobodies for targeted immunolabelling and antigen manipulation in living cells“; online:
Prof. Dr. M. Cristina Cardoso
TU Darmstadt Department of Biology
Tel.: +49-6151 16-21882
Prof. Dr. Christian Hackenberger
Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP)
Tel: +49-30 94793-181
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For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
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Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
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Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
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code you linked to expects the server's certificate to be in the
device's trusted root certificate store, or at least signed by a trusted
root certificate authority. The error you are getting suggests that this
is not the case.
That error means the certificate is not trusted. By definition, a
self-signed certificate is not trusted because it isn't signed by a trusted
root certificate authority (so there's no way to verify that the signer of
the certificate is who they say they are).
If you just want the benefits of SSL encryption without the protection
from MITM attacks, you can bypass the server check by doing something like
the following in the NSURLConnection delegate's
- (void)connection:(NSURLConnection *)connection
Note that this will not prevent MITM attacks, since you are now allowing
a connection to any SSL host, but if you truly want that kind of protection
you shouldn't use a self-signed certificate. If you just want the
encryption offered by SSL, a self-signed certificate is fine.
That said, you can do server authentication if you are bundling
the server certificate in with your application - this is known as
certificate pinning. You would need to add code in the
didReceiveAuthenticationChallenge method above to compare the
server's certificate with the one that's embedded in your application and
have it trust ONLY that specific certificate and no other. This of course
means that if the certificate on your server ever expires or changes, your
clients will no longer be able to connect (until you rebuild and
redistribute your application with the new certificate). It also means
that if your server's private key is ever stolen or compromised, you won't
be able to revoke it and issue a new one, and the Bad Guys will be able to
impersonate your server to any clients that try to connect using the
compromised key. Using a certificate issued by a trusted root CA avoids
both problems, and is still the recommended way to go if you truly need
server authentication. That way you can revoke the certificate if you ever
need to, issue a new one, and everything will still work. | <urn:uuid:10b3dcb2-a628-4278-8020-1e50775b9867> | 2.84375 | 460 | Q&A Forum | Software Dev. | 34.325181 | 95,631,102 |
“This is what would happen during a major earthquake along the Mississippi River,” says Luna, an associate professor of civil, architectural and environmental engineering at Missouri University of Science and Technology.
Researchers don’t fully understand the liquefaction process for silts (they have a better understanding of how it works with sands), but Luna is confident, based on his tests, that a 6.5 magnitude earthquake or bigger would cause solid surfaces along the banks of the Mississippi River to turn, momentarily, into liquid.
This would be very bad. For instance, liquefaction of river silts would cause bridges to fail in St. Louis during a big earthquake.
Last spring, Luna presented a paper, “Liquefaction Behavior of Mississippi River Silts,” at the Geotechnical Earthquake Engineering and Soil Dynamics Conference in Sacramento, Calif. The conference is only held once every 10 years.
“We are providing data points to what is already known about liquefaction in other areas,” Luna says.
Researchers and scientists have had plenty of chances to study what happens during and immediately after a major earthquake in well-shook places like California. But the last really big quakes in the Midwest occurred in 1812.
We do know that, due to differences in geography, major quakes in the Midwest are felt over a greater area than similar-sized quakes in California.
According to Luna, river silts in the New Madrid region are similar to those in earthquake-prone areas of China and India.
Last May, a devastating 7.9 earthquake caused extensive damage throughout the Sichuan province in the interior of China.
Lance Feyh | Newswise Science News
New research calculates capacity of North American forests to sequester carbon
16.07.2018 | University of California - Santa Cruz
Scientists discover Earth's youngest banded iron formation in western China
12.07.2018 | University of Alberta
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
18.07.2018 | Materials Sciences
18.07.2018 | Life Sciences
18.07.2018 | Health and Medicine | <urn:uuid:4fa9c371-6685-4def-bfb2-0bd3977840d9> | 3.671875 | 981 | Content Listing | Science & Tech. | 38.948954 | 95,631,109 |
2018-07-05 | Editor : et_editor 740 pageviews
Japanese Researchers Use AI-Based Model to Discover Better Polymers for Organic PV Cells
A major challenge in the development of organic photovoltaic (PV) cells is obtaining the polymer materials that meet the design requirements. Because there are millions of possible combinations of molecules that go into polymer materials, researchers generally have to painstakingly synthesize and test each of the polymers they have created through trial-and-error experimentation. Recently, material scientists at Osaka University in Japan have found a way to shorten and optimize the process for determining the right combinations for polymers that will be used in organic PV cells. Instead of relying on the traditional experimentation and simulation, these scientists now use a computer-powered artificial intelligence (AI) system that automates the search for the suitable combinations. Their findings reveal that AI has the potential to radically improve the designs of organic PV cells and speed up their commercialization.
Organic PV cells have a chance to become the next big breakthrough in solar power because they have several important advantages over the conventional PV cells that are made of crystalline silicon. First, organic PV cells can be made on flexible substrates, thus offering new design possibilities. Second, a very efficient light absorption capability can be derived from a thin layer of organic material, while additional conductive polymers or molecular units can assist in this process and in the transfer of electric charges. Lastly, organic PV cells can be mass produced using a simple printing process with low-cost materials.
However, the conversion efficiency rates of the current generation of organic PV cells are within the range of 11-12%. The overall performance of the organic cells is therefore still not good enough for full-scale commercialization, which requires an efficiency rate of at least 15%. The main reason why researchers have been unable to substantially raise the conversion efficiency of organic cells is the challenge of devising, synthesizing, and testing polymers for solar materials. Shinji Nagasawa, a member of the research team at Osaka University, pointed out that the properties of polymers can affect the flow of the short-circuit current, which in turn can have an impact on the cell’s conversion efficiency.
Akinori Saeki, another member of the research team, added that a polymer has a complex structure composed of many sub-units (e.g. a donor unit, an acceptor unit, a spacer, and alkyl chains). Saeki said that even if the number of possible choices of each sub-unit is limited to 20, the number of possible combinations for researchers to synthesize will still exceed 1 million. Saeki also noted that there are many other factors affecting the conversion efficiency of an organic PV cell besides the properties of the polymer materials. These factors include the film morphology, the p-n junction, and the solubility of the materials. The applications of advanced modeling, even ones based on quantum chemistry, cannot accurately predict the efficiency of a solar cell.
Since testing individual polymer samples is time and resource consuming, the team at Osaka University hit upon the idea of using AI to accelerate the searching and screening of samples.
(Credit: Osaka University)
The researchers first created a data set that included the properties of 1,200 organic cells from 500 studies. Then, they used a type of machine learning algorithm called Random Forest to build a custom model that uses the data set as a reference to predict the theoretical efficiency of a potentially new polymer sample. This AI-based model takes account of important polymer attributes such as band gap, molecular weight, chemical structure, and electronic properties.
With the incorporation of the Random Forest algorithm, the model has an enhanced ability to find the connections between properties of materials and their contributions to the efficiency of an organic PV cell. Researchers can screen prospective polymers based on their theoretical efficiency rates that are calculated by the model. This faster filtering process also allows researchers to discover new polymers that have not been tested previously.
The AI-based model did not yield the expected results in the actual trials. Nevertheless, it has given researchers a greater understanding of the relationship between the structure and properties of a material. The research team stated that more parameters such as the polymer’s solubility in water will be added into the model to improve its applicability.
Saeki said that the model is far from perfect as its accuracy is around 20-50%, but it can immediately forecast similar results that would take months to produce with experiments and simulations in a laboratory setting. Hence, this AI-based tool can dramatically accelerate the design and development of solar cells. While the Random Forest algorithm cannot fully replace the human thought process, it can be used to assist molecular designers in deciding the suitable combination for a polymer and lighten their workload.
The description of the model and the findings of the research team at Osaka University were published in the Journal of Physical Chemistry Letters on 7 May 2018.
(The above article is an English translation of a Chinese article written by Daisy Chuang. The credit of the photo at the top of the article goes to Katy Warner via Flickr and falls under the license of CC BY 2.0.) | <urn:uuid:2df34bbe-3d5d-428d-8c64-4180af3ccac5> | 3.46875 | 1,055 | News Article | Science & Tech. | 25.90426 | 95,631,124 |
Group 8 element
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|Group 8 in the periodic table|
26 Transition metal
44 Transition metal
76 Transition metal
108 Transition metal
Group 8 is a group of chemical element in the periodic table. It consists of iron (Fe), ruthenium (Ru), osmium (Os) and hassium (Hs). They are all transition metals. Like other groups, the members of this family show patterns in electron configuration, especially in the outermost shells, resulting in trends in chemical behavior.
|Z||Element||No. of electrons/shell|
|26||iron||2, 8, 14, 2|
|44||ruthenium||2, 8, 18, 15, 1|
|76||osmium||2, 8, 18, 32, 14, 2|
|108||hassium||2, 8, 18, 32, 32, 14, 2|
Hassium has not been isolated in macroscopic pure form, and its properties have not been conclusively observed; only iron, ruthenium, and osmium have had their properties experimentally confirmed. All three elements are typical silvery-white transition metals, hard, and have high melting and boiling points.
Iron has been known and used to make tools since antiquity. Ruthenium was first identified in 1844 in platinum ores, after all other platinum group metals, including Osmium, which was discovered in 1803; by dissolving impure platinum, salts were created. In a graphite-like dust always found in these salts, it was concluded that a new metal must be present, which would be Osmium. Ruthenium was first discovered in the form of ruthenium oxide in a similar manner. Hassium was discovered in 1984 by a team led by Peter Armbruster and Gottfried Münzenberg by bombarding lead-208 with iron-58.
Iron is the most common element within the entire earth; most of the core is iron and there is a substantial amount of iron in the mantle and crust as well. Ruthenium and osmium are two of the rarest elements on earth, with ruthenium only found in small amounts in platinum ores. Osmium is the least abundant stable element in the earth's crust, only found in minor traces in platinum ores. Hassium is only produced in nuclear reactors and has never been observed in nature nor isolated in pure form.
Iron is an essential nutrient for all living organisms, from archaea to humans. It is a major component in hemoglobin, a protein that makes blood red and transfers oxygen to muscles, and is also found in many other proteins. Ruthenium, osmium, and hassium have no known role in the human body. | <urn:uuid:4b34c520-9a63-4635-8ad0-3f436078e267> | 3.78125 | 626 | Knowledge Article | Science & Tech. | 51.4175 | 95,631,136 |
The Alps are steadily "growing" by about one to two millimeters per year. Likewise, the formerly glaciated subcontinents of North America and Scandinavia are also undergoing constant upward movement.
This is due to the fact that at the end of the Last Glacial Maximum (LGM) about 18,000 years ago the glaciers melted and with this the former heavy pressure on the Earth's surface diminished.
The ice reacted rapidly to climate change at that time whereas the Earth's crust is still responding today to this relatively sudden melting of ice. During the LGM the Alps were also coated with an ice cap that temporarily reached far into the alpine foreland. The extent of glaciation was much smaller here than on the subcontinents of North America and Scandinavia.
This is why it was assumed for a long time that the retreat of the ice cap back then did not play a significant role in the steady uplifting of the Alps today. However, an international team with the participation of the GFZ scientists Dirk Scherler and Taylor Schildgen have now been able to show that the loss of the LGM ice cap still accounts for 90 percent of today's uplifting of the Alps.
Vertical motions of the Earth's crust are mainly caused by tectonic deformation due to movements of tectonic plates, and by volcanism, and unloading of water, ice, and sediments. The movement of the crust can be measured by geodetic methods via satellites and ground stations.
For old, tectonically stable continents like the subcontinents of North America and Scandinavia it has been known for a long time that vertical motion is almost exclusively caused by the so called postglacial "rebound effect" - i.e. the upward motion of the crust due to the thawing of the glaciers. In young mountain belts such as the Alps, however, complex mechanisms come into play that mutually effect each other:
The African Plate subducts below the Eurasian Plate, and the Adriatic Plate -- a sub-plate of the African Plate -- moves counterclockwise below the Eurasian Plate. Furthermore, as in Scandinavia and North America, there is unloading due to erosion and sediment transport, and "deglaciation". The causes for today's uplift of the Alps has been a matter of debate for over a quarter of a century.
For a long time it was assumed that the uplift is primarily caused by erosion and sediment transport, mainly by rivers, towards the foreland. The new study compares by how much erosion, ice unloading, and local tectonics contribute to the vertical motion of the Alps. The scientists use models supported with drill core data to show that the better part of postglacially, and therewith after the end of the main glacial phase, eroded material was deposited within the orogen.
Hence, this process can be excluded as a main cause for the alpine uplift. The models, however, show that, just like in Scandinavia and America, the uplift-signal is best explained with a relieving compensatory movement after the decline of the LGM-glaciers: Within only 3,000 years the glaciation of the Alps decreased by about 80 percent. Only about 10 percent of today's uplift can be attributed to sediment unloading. Locally, especially in parts of Austria, tectonic effects add to the uplift, likely caused by the circular motion of the Adriatic sub-plate. With their models the scientists are able to show that the glacial load weighed about 62,000 gigatonnes, while the postglacial sedimentary unloading only accounts for about 4,000 gigatonnes.
Original study: Jürgen Mey, Dirk Scherler, Andrew D. Wickert, David L. Egholm, Magdala Tesauro, Taylor F. Schildgen, Manfred R. Strecker. Glacial isostatic uplift of the European Alps. Nature Communications 7:13382. DOI: 10.1038/ncomms13382
Josef Zens | EurekAlert!
Global study of world's beaches shows threat to protected areas
19.07.2018 | NASA/Goddard Space Flight Center
NSF-supported researchers to present new results on hurricanes and other extreme events
19.07.2018 | National Science Foundation
A new manufacturing technique uses a process similar to newspaper printing to form smoother and more flexible metals for making ultrafast electronic devices.
The low-cost process, developed by Purdue University researchers, combines tools already used in industry for manufacturing metals on a large scale, but uses...
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
20.07.2018 | Power and Electrical Engineering
20.07.2018 | Information Technology
20.07.2018 | Materials Sciences | <urn:uuid:63f5daea-a632-45b8-b837-cbc42c1e2a79> | 4.21875 | 1,425 | Content Listing | Science & Tech. | 43.424041 | 95,631,149 |
Radiometric dating, or radioactive dating as it is sometimes called, is a method used to date rocks and other objects based on the known decay rate of radioactive isotopes.Different methods of radiometric dating can be used to estimate the age of a variety of natural and even man-made materials.The boat of a pharaoh was discovered in a sealed crypt and reassembled in a museum near the pyramids (see Fig. The age of our galaxy and earth also can be estimated using radioactive dating.Using the decays of uranium and thorium, our galaxy has been found to be between 10 and 20 billion years old and the earth has been found to be 4.6 billion years old. Within experimental error, this estimate agrees with the 15 billion year estimate of the age of the Universe.For example, in 1991, two hikers discovered a mummified man, preserved for centuries in the ice on an alpine mountain.Later called Ötzi the Iceman, small samples from his body were carbon dated by scientists.The technique of comparing the abundance ratio of a radioactive isotope to a reference isotope to determine the age of a material is called radioactive dating.Many isotopes have been studied, probing a wide range of time scales.
The thing that makes this decay process so valuable for determining the age of an object is that each radioactive isotope decays at its own fixed rate, which is expressed in terms of its half-life.
Scientists can use certain types of fossils referred to as index fossils to assist in relative dating via correlation.
Index fossils are fossils that are known to only occur within a very specific age range.
However, rocks and other objects in nature do not give off such obvious clues about how long they have been around.
So, we rely on radiometric dating to calculate their ages. | <urn:uuid:26951528-ea95-443a-ac70-b92a5303e5fa> | 3.984375 | 370 | Knowledge Article | Science & Tech. | 40.212928 | 95,631,154 |
Can we define marine habitat use by seabirds without costly at-sea observational data? (innovation fund)
Our waters support the greatest diversity of seabirds on Earth, but defining where birds are and in what numbers can be extremely expensive. We are investigating whether relative environmental suitability (RES) models could produce sufficiently accurate estimates of seasonal seabird distributions, at a much lower cost than boat-based observations.
Project leader: David Thompson, NIWA
Can we predict which seabirds are where?
New Zealand waters support the greatest diversity of seabirds on Earth. However, there is little information available about where seabirds are found within New Zealand’s EEZ, and how their distributions (numbers) vary with time. This lack of data often means that managers, decision-makers, Māori, stakeholders and the public do not have the detailed and robust information needed to gauge how particular threats in the marine environment could affect these high-profile, protected species.
Unfortunately, getting detailed and systematic at-sea data about where sea birds are and in what numbers through conventional boatbased field work is extremely expensive. Relative environmental suitability (RES) models are cheaper because they do not incorporate location data, they rely upon knowledge of the environmental characteristics that particular seabird species prefer.
We are investigating whether RES models are sufficient to produce accurate estimates of seasonal seabird distributions – or if seabird location data from sightings and electronic tracking devices are more accurate. To do this we are comparing species-specific RES models to habitat suitability models that are produced from either observational data or location data from electronic tags.
This tiered novel approach has the potential to produce new information about how seabirds use the marine environment whilst making huge resource savings.
Latest news and updates
Improving marine management is critical to New Zealand's future health and wealth, but research in isolation is not enough. Excellent engagement with, and participation from, all users and sectors of society is essential.
We therefore invite comment on our draft strategy for Phase II (2019–2024). This strategy has been co-developed with Māori and stakeholders.
During Seaweek, more than 4,600 school pupils joined 6 Sustainable Seas researchers for 3 days of marine science fieldwork in Tasman Bay, as part of the LEARNZ virtual field trip Sustainable seas – essential for New Zealand’s health and wealth. | <urn:uuid:97b5ce6e-569c-4548-baa6-cb40936bbb2c> | 3.09375 | 497 | News (Org.) | Science & Tech. | 16.71487 | 95,631,158 |
Formulation of Plasma Theory
In this chapter, we begin the exposition of the theory of plasmas. We shall restrict ourselves primarily to plasmas consisting of charged particles which can be represented by point charge and point mass. Each particle is assumed to obey the classical nonrelativistic equations of motion and the plasma has no net charge, namely, there are equal number of negative charges (electrons) and positive charges (ions).
KeywordsVlasov Equation Pressure Tensor Electron Fluid Vlasov System Collisionless Boltzmann Equation
Unable to display preview. Download preview PDF. | <urn:uuid:f534514d-2e82-4c39-a505-571d4f7c3852> | 3.265625 | 127 | Truncated | Science & Tech. | 22.891241 | 95,631,163 |
Elementary Real Analysis
by B. S. Thomson, J. B. Bruckner, A. M. Bruckner
Publisher: Prentice Hall 2001
Number of pages: 735
Elementary Real Analysis is written in a rigorous, yet reader friendly style with motivational and historical material that emphasizes the "big picture" and makes proofs seem natural rather than mysterious. Introduces key concepts such as point set theory, uniform continuity of functions and uniform convergence of sequences of functions. Covers metric spaces. Ideal for readers interested in mathematics, particularly in advanced calculus and real analysis.
Home page url
Download or read it online for free here:
by Martin Smith-Martinez, et al. - Wikibooks
This introductory book is concerned in particular with analysis in the context of the real numbers. It will first develop the basic concepts needed for the idea of functions, then move on to the more analysis-based topics.
by Shlomo Sternberg
The topology of metric spaces, Hilbert spaces and compact operators, the Fourier transform, measure theory, the Lebesgue integral, the Daniell integral, Wiener measure, Brownian motion and white noise, Haar measure, Banach algebras, etc.
by Pierre Schapira - Université Paris VI
The notes provide a short presentation of the main concepts of differential calculus. Our point of view is the abstract setting of a real normed space, and when necessary to specialize to the case of a finite dimensional space endowed with a basis.
by G.H. Hardy - Cambridge University Press
This classic book has inspired successive generations of budding mathematicians at the beginning of their undergraduate courses. Hardy explains the fundamental ideas of the differential and integral calculus, and the properties of infinite series. | <urn:uuid:edd05f14-6c6a-45f2-88aa-bf08c50b5d6e> | 2.71875 | 365 | Content Listing | Science & Tech. | 31.925791 | 95,631,200 |
The team looked at the mass balance of the Antarctic ice sheet from 1992 to 2017 and found ice losses from Antarctica raised global sea levels by 0.3 inches (7.6 millimeters), with a sharp uptick in ice loss in recent years.
West Antarctica experienced the most acceleration in ice loss among regions studied during the research period, growing from 53 billion tons a year in the 1990s to 159 billion tons annually in the final five years.
This is unedited, unformatted feed from the Press Trust of India wire. It's an untenable situation and one that could lead to runaway melt that would raise sea levels more than 10 feet. Thanks to the satellites that our space agencies have launched, we can now track their ice losses and global sea-level contribution with confidence. "We hadn't seen these kinds of structures near the base of an ice sheet before, and the best explanation is that they formed as this portion of the ice sheet re-grounded".
The only period when the quantity of ice lost dropped was between 1997 and 2002, when Antarctica saw a loss of 38 billion tonnes per year compared to 49 billion per year for the five years prior to that period.
The researchers estimate that ice loss in the period between 1992 and 2017, could be as high as 2,720 billion tonnes (although the number may also be as low as 1,390 billion tonnes, due to uncertainties in the data).
Results from the project - known as the Ice Sheet Mass Balance Inter-Comparison Exercise - were published today in Nature.
The study found more than 10 percent of Antarctica's coastal glacier are now retreating more than 25m per year.More news: Morocco 0-1 Iran: Late Own Goal Hurts Atlas Lion
"A lot of the argument has been made from stakeholders that are not quite as interested in dealing with climate change that the East Antarctic ice sheet is actually gaining mass - therefore we don't need to worry", said Michele Koppes, a glaciologist at the University of British Columbia who was not involved with the study.
This chart show Antarctic ice sheet's contribution to sea level rise over time.
Antarctica is not the only contributor to sea-level rise.
Antarctic ice has retreated and advanced and retreated again many times over the millennia: there has always been argument about how much of the change is because of natural cycles, how much because of human-induced climate change.
"Satellites have given us an awesome, continent-wide picture of how Antarctica is changing", Pippa Whitehouse, of Durham University, said.
This latest IMBIE is the most complete assessment of Antarctic ice mass changes to date, combining 24 satellite surveys of Antarctica and involving 80 scientists from 42 global organizations.
Covering twice the area of the continental United States, Antarctica is blanketed by enough ice pack to lift global oceans by almost 60 metres (210 feet). However, scientists say it's not enough to replace the amount of ice lost.More news: Mohamed Salah 'almost 100 per cent' fit for Egypt's World Cup opener
Shepherd said the ice on West Antarctica can be melted by very small changes in ocean temperature.
"What we have seen as the climate has warmed is that more warm water is reaching the Antarctic ice sheet and that's what is melting the sea ice", he said.
How has this research contributed to our understanding of climate change?
The biggest losses have come from the Pine Island and Thwaites Glaciers, as well as ice shelf collapse on the Peninsula like that of the much-watched Larsen C break last summer.
The findings not only clarify the past impact of rising temperatures on East Antarctic ice, said Shakun, but confirm the accuracy of models scientists are using to assess past and future consequences of a warming planet.
Duanne White, associate professor at the University of Canberra, commended the paper as "a thorough assessment of the current state of knowledge of Antarctic ice loss".More news: Kim commits to 'complete denuclearization' during nuclear summit with Trump | <urn:uuid:73f51bd5-26cd-4dd4-b9a3-9d26a04945e4> | 3.71875 | 827 | News Article | Science & Tech. | 41.925308 | 95,631,217 |
Its a reusable code which exports specific objects, making them available for other modules through dependency references to be used their programs.
AMD implementation is used by jQuery, Dojo, Firebug etc. There are various javascipt module loaders like RequireJS, Browserify, Webpack, SystemJS
Math.round function is used to round a number to its nearest integer. If fractional part of the number >=0.5 then the argument is rounded to next higest integer.
If fractional part of the number < 0.5 then the argument is rounded to lowest integer.
eg. Math.round(7.5) = 8
Math.round(7.2) = 7
Math.ceil function returns integer greater than or equal to a given number. Ceil means think of the ceiling of the room which is above your head.
eg. Math.ceil(7.5) = 8
Math.ceil(7.2) = 8
Math.ceil(7) = 7
Math.ceil(-7.5) = -7
Math.ceil(-7.2) = -7
Math.floor function returns integer lesser than or equal to a given number. Floor means think of the floor of the room which is below you
eg. Math.floor(7.5) = 7
Math.floor(7.2) = 7
Math.floor(7) = 7
Math.floor(-7.5) = -8
Math.floor(-7.2) = -8
What is a BLOb?
BLOb, Binary Large OBject : is a collection of binary data stored as a single entity in a database management system. Blobs are typically images, audio or other multimedia objects. Database support for blobs is not universal. Blobs were originally just big amorphous chunks of data invented by Jim Starkey at DEC(Digital Equipment Corporation)
The four BLOB types are
- TINYBLOB : A BLOB column with a maximum length of 255 (28 – 1) bytes. Each TINYBLOB value is stored using a one-byte length prefix that indicates the number of bytes in the value
- BLOB : A BLOB[(M)] column with a maximum length of 65,535 (216 – 1) bytes. Each BLOB value is stored using a two-byte length prefix that indicates the number of bytes in the value.
An optional length M can be given for this type. I
- MEDIUMBLOB : A BLOB column with a maximum length of 16,777,215 (224 – 1) bytes. Each MEDIUMBLOB value is stored using a three-byte length prefix that indicates the number of bytes in the value.
- LONGBLOB : A BLOB column with a maximum length of 4,294,967,295 bytes or 4GB (232 – 1). Each LONGBLOB value is stored using a four-byte length prefix that indicates the number of bytes in the value.
I came across this line #!/usr/bin/env and was wondering what is this and for what? I browsed some articles to get some overview about it. Any script beginning with #! is called shebang(other names are hashbang, sha-bang etc). When a script with shebang is run, it passes the file as an argument to the specified program instead of trying to execute it.
The form of a shebang interpreter directive is as follows:
- #! interpreter [optional-arg]
The interpreter must be an absolute path to an executable
In order to run the script, we need to tell the shell three things:
That the file is a script –>accomplished using shebang #!
Which interpreter we want to execute the script
The path of said interpreter
2 and 3 is accomplished using env.
Some typical shebang lines:
#!/bin/sh — Execute the file using sh
#!/usr/bin/perl — Execute using Perl
#!/usr/bin/python — Execute using Python
Shebang lines may include specific options that are passed to the interpreter.
What is so special about frameworks? We hear about these web frameworks frequently like Django, Cake PHP, Rails etc. Let’s dive into frameworks.
Framework gives you a ready-made code base which has been tested and designed by many developers and is ready to use solution for common generic problems. That is, it provides with a generic functionality which has flexibility to be changed, which helps you take advantage of this generality. It provides powerful template where the logic can be injected, helps in simplifying complex things.
- Saves lot of time, DRY(Don’t Repeat Yourself) means fewer lines of code
- Provides a standard through which the user can develop the module or a complete application instead of starting from lower level details.
- More time can be devoted in developing the software and not in preparing the environment and tools of development.
- Code is extensible for future use with clean code
Heads Up! Framework doesn’t work everywhere, for instance smaller projects which require simple coding seems to work faster than setting up a framework.
Tip for those running python script on Notepad++
Press F5 to run current script and to avoid output screen disappear instantaneously type in command: cmd /k python -i “$(FULL_CURRENT_PATH)”. | <urn:uuid:c5f740f7-cf98-424d-b554-eb4cc5b5b959> | 3.46875 | 1,150 | Personal Blog | Software Dev. | 65.798449 | 95,631,223 |
Introducing Natural Resources Paperback
by Graham Park
Part of the Introducing Earth and Environmental Sciences series
Over the many millennia that the human race has inhabited our planet, a use has been found for almost everything that is to be found on it.
However, since the Industrial Revolution, many of the resources that we have come to rely on are being depleted, some at an alarming rate.
Misuse of others, such as fossil fuels, is causing such damage to the environment that measures are being taken at an international level to restrict their useIntroducing Natural Resources explains how the natural resources of the Earth originated, by outlining the astronomical and geological evolution of the planet in the early period of its existence.
The genesis, mode of occurrence, and abundance of the various non-renewable mineral resources are described, together with the methods of extraction, extent of reserves, and any environmental problems.
The use of renewable resources, such as solar energy, air, and water, are then discussed, together with plant and animal life, which are renewable resources only if properly managed.
The book concludes with a summary of future issues in resource management.Copiously illustrated, this book is intended for those whose interest in natural resources has been stimulated, perhaps by media coverage of declining resources or environmental pollution, and who want to better understand the issues involved. Technical terms are kept to a minimum and are explained in a glossary.
- Format: Paperback
- Pages: 160 pages, illustrations
- Publisher: Dunedin Academic Press
- Publication Date: 10/12/2015
- Category: Earth sciences
- ISBN: 9781780460482 | <urn:uuid:186a50a2-a509-4151-a3b4-86786a8f0009> | 3.40625 | 335 | Product Page | Science & Tech. | 7.250577 | 95,631,225 |
Measurements in physics are clever things. You’d trust that endeavors to evaluate a portion of the central properties of the Universe would take after a basic example: they’d begin with extensive blunder bars, in any case, over the long haul, estimating innovation enhances and the mistake bars shrivel. In a perfect world, the esteem would then remain pleasantly inside the past mistake.
It never truly works that way. Much of the time, measurements group together for some time before another set influences a jump to some place to else, outside the mistake limits.
What’s more, even as innovation enhances, a few arrangements of mistake bars unshakably decline to cover.
Another paper out this week shows this is the situation with the Fine Structure Constant, which depicts the quality of the electromagnetic power.
In any case, rather than crediting it to the caprices of measurement, the specialists propose that the distinction could be genuine—and it discloses to us something about what physics may lie past the Standard Model.
The Fine Structure Constant is a measure of electromagnetic power, and that power appears in an expansive number of marvels. This implies there are a lot of approaches to do measurements that disclose to us something about the estimation of the Fine Structure Constant.
With regards to high-accuracy measurements, scientists have thought of two distinctive methods for doing it. The main depends on molecule physics, and direct measurements of the attractive properties of the electron. The second has been to think about how particles cooperate with light.
After some time, we’ve thought of better methods for estimating both of these, and the mistake bars on our measurements have contracted in like manner. Furthermore, while the qualities delivered by them have become nearer, the blunder bars are willfully declining to cover.
The information of the new paper is a give an account of another measurement, this one utilizing associations amongst photons and iotas.
The analysis itself is really astounding. Like the LIGO gravitational-wave locators, it depends on the way that impedance between waves can enroll amazingly unpretentious changes in area.
Not at all like LIGO, be that as it may, the waves aren’t light; they’re particles. Exploiting the quantum idea of particles, the analysts send clusters of them along various ways as waves and afterward inspire them to meddle with each other.
Lasers are utilized to direct the molecules along the ways, making the obstruction seriously delicate to the communications between the lasers’ photons and the iotas.
Furthermore, the quality of those connections, as we stated, are impacted by the estimation of the Fine Structure Constant.
The new measurements give a three-overlap diminishment in the blunder contrasted with past work, with the exactness being inside ±2 × 10-10.
Be that as it may, the issue on everyone’s mind here is the scope of qualities secured by those mistake bars. The scope of qualities is altogether contained inside the mistake bars of a past measurement made utilizing an iota interferometer.
What’s more, neither of these measurements covers at all with the most noteworthy accuracy measurement done by straightforwardly estimating the electron. The distinction between the two measurements has a hugeness of 2.4 sigma.
What if it’s real?
It wouldn’t be absurd to expect that, with assist measurements, this distinction would recoil or even vanish altogether. Be that as it may, there are a few motivations to figure it may not.
The connection between the electron’s conduct and the Fine Structure Constant is set by the Standard Model, and there have been a considerable measure of thoughts set forward about how the Standard Model may be moved forward.
Some of these would change the electron’s conduct, so the scientists chose to consider the distinction between the measurements important.
As such, they expected the two measurements were correct and considered how changes to the Standard Model could create the obvious distinction between them.
One situation where this issues is a theoretical molecule called a dim photon. dark photon would deliver a distinction in the measurements of the Fine Structure Constant, yet it would be the other way of the distinction found in these analyses.
As it were, dull photons would exacerbate the situation. By differentiate, another theoretical molecule, the dull hub vector boson, isn’t precluded by this new measurement.
It is not necessarily the case that these examinations have authoritatively revealed to us anything about these speculative augmentations to the Standard Model.
There’s as yet the shot that the electron measurements aren’t right, and there are a few activities in progress that will have the capacity to say more in regards to that plausibility.
In any case, it unquestionably demonstrates those ventures merit seeking after, since a proceeded with distinction more than a few free measurements would begin to look intriguing.
What’s more, on a totally random side note, the scientists behind the new work take note of that it additionally gives an institutionalized methods for estimating indisputably the mass of the particles, which could be utilized to give an approach to define the kilogram without depending on lumps of metal. Reward! | <urn:uuid:92c3ab3f-fe37-47a1-8eee-dacfd854cb65> | 2.734375 | 1,073 | Truncated | Science & Tech. | 32.433095 | 95,631,281 |
A) interaction between green and blue frequencies of light.
B) reflection of red light.
C) reflection of greenish-blue light.
D) absorption of greenish-blue light.
E) absorption of red light.
2.Atmospheric refraction tends to make daytimes
A) longer. B) shorter. C) no change in day length
Recently Asked Questions
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The continental crust is commonly viewed as being formed in subduction zones, but there is no consensus on the relative roles of oceanic or continental arcs in the formation of the continental crust. The main difficulties of the oceanic arc model are how the oceanic arcs can be preserved from being subducted, how we can trace the former oceanic arcs through their high-Si products, and how the oceanic arcs can generate the high-Si, K-rich granitoid composition similar to the upper continental crust. The eastern Qinling orogen provides an optimal place to address these issues as it preserves the well-exposed Erlangping oceanic arc with large amounts of granitoids. In this study, we present an integrated investigation of zircon U–Pb ages and Hf–O isotopes for four representative granitoid plutons in the Erlangping unit. In situ zircon SIMS U–Pb dating indicated that the Zhangjiadazhuang, Xizhuanghe, and Taoyuan plutons formed at 472±7, 458±6 and 443±5Ma, respectively, all of which postdated the deep subduction of the Qinling microcontinent under the Erlangping oceanic arc. The Zhangjiadazhuang, Xizhuanghe, and Taoyuan plutons are sodic granitoid and have highly positive εHf(t) (+7.6 to +12.9) and relatively low δ18O (4.7–5.0‰) values, which were suggested to result from prompt remelting of hydrothermally altered lower oceanic crust of the accreted Erlangping oceanic arc. The zircon grains from the Manziying monzogranitic pluton show similar Hf–O isotopic compositions to those of the Xizhuanghe pluton, and thus the Manziying monzogranitic pluton was likely derived from the dehydration melting of previous tonalites as exemplified by the Xizhuanghe pluton. The deep subduction of Qinling microcontinent resulted in the accretion of the Erlangping oceanic arc, which implies that arc–continent collision provides an effective way for preventing oceanic arcs from being completely subducted. The highly positive εHf(t) and relatively low δ18O values of zircon grains from the granitoids in the Erlangping unit reveal that the continental crust can acquire its high-Si, K-rich nature from accreted oceanic arcs through differentiation by post-accretional magmatism, and thus highlight the significance of oceanic arcs for the generation of continental crust.
Geochimica et Cosmochimica Acta – Elsevier
Published: Jun 1, 2016
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Bookmark this article. You can see your Bookmarks on your DeepDyve Library. | <urn:uuid:d83d3760-293c-46be-a543-a627476846a5> | 2.671875 | 916 | Truncated | Science & Tech. | 40.164054 | 95,631,323 |
Affect of solar wind on Earth
How does the solar wind affect Earth?
There are different kinds of notable effects, which will depend on the power of the solar wind as earth is protected by its magnetic field:
- troubles in satellite communications,
- troubles in cell phone communications,
- in case of very strong wind, even troubles in electrical power delivery can occur.
by John Harper 7 years ago
Solar flares from 'huge space storm' will cause devastation, the world could face widespread power blackouts and be left without critical communication signals for long periods of time, after the earth is hit by a once-in-a-generation “space storm”, Nasa has warned.I. How will this affect our...
by Aya Katz 5 years ago
Which alternative energy source is more efficient and cheaper to maintain: solar panels or windmills?
by Aficionada 7 years ago
A short while ago tonight I scanned an article that said "Dramatic solar flare [Tuesday, June 7] could disrupt Earth communications [Wednesday, June 8]."Recently I have been trying to research as much as I can about solar flares, because of a chilling coincidence.In one of my hubs, I...
by Shil1978 6 years ago
Which renewable energy sources offer the most promise?
by Bill Russo 7 years ago
Should we give tax breaks to start-up companies developing wind, water, or solar power?Should we increase tax advantages to homeowners who install wind, water or solar power?
by Sabin B Rajalim 3 years ago
What is solar storm?I heard that there is a big solar storm coming this december. What could be the effect, the danger of this to us? Any precaution or protection to be taken for this?
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New model could point way to microbiome forecasting in the ocean
- September 25, 2016
- 3774 Views
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Each and every organism on Earth is exposed to the influence of various environmental conditions and of other living organisms. These factors can trigger stress and make the living organism more vulnerable to external influences. A team of researchers has now succeeded in using aquatic organisms to demonstrate that the presence of environmental stress multiplies the effects of pollutants on organisms. Furthermore, they have developed a model that makes it possible to use the intensity of the environmental stress as a basis to predict the increased impact of pollutants. | <urn:uuid:3fdbbaae-73d5-4fee-97ea-25b9adc460a6> | 2.796875 | 126 | Truncated | Science & Tech. | 23.170745 | 95,631,348 |
20 July 2018
Crowdsourcing identification of toxic compounds
Published online 12 August 2015
A large number of algorithms can be used to evaluate the toxicity of compounds and identify risks to humans early.
Researchers from institutes around the world, including the Jordan University of Science and Technology, have evaluated the performance of contestants in an international challenge to predict the toxicity of potentially harmful environmental compounds1.
Dozens of teams took part in the challenge, which was organized by the DREAM Challenges initiative, the non-profit Sage Bionetworks, and the US National Institutes of Health. The teams competed to predict how the toxicity of compounds varied between 884 different cell lines on the basis of genetic differences. Overall, the algorithms that the participants developed were more effective at classifying which compounds were cytotoxic than in predicting the level of toxicity.
In the second part of the challenge, teams were tasked with using a compound's structure to predict its average toxicity in a population and the variability of this response. This could help manufacturers evaluate new compounds before submitting them for expensive testing procedures.
Analysis of the results revealed that the aggregated predictions of all the algorithms were generally more robust than the individual algorithms. “The poor methods included in the aggregation degrade the performance less than the gain derived from the inclusion of good methods,” explains Federica Eduati, one of the study's lead authors. “This 'wisdom of the crowds' approach is particularly important in a real life situation.”
- Eduati, F. et al. Prediction of human population responses to toxic compounds by a collaborative competition. Nature Biotechnology http://10.1038/nbt.3299 (2015) | <urn:uuid:c0fb63e6-6c38-4496-8943-4147d8628d1a> | 3.125 | 345 | Truncated | Science & Tech. | 23.190571 | 95,631,374 |
Install PHP on Windows 10. 8. 2008 in Php | 1 Comments | Author: | 2351 clicks
You must have a web server up and running on your Windows system, else you will not be able to run PHP Scripts.
SQL IN operator 10. 8. 2008 in Php | 1 Comments | Author: | 2205 clicks
The IN operator checks a value within a set of values separated by commas and retrieve the rows from the table which are matching. The IN returns 1 when the search value present within the range other wise returns 0.
SQL Data Type 10. 8. 2008 in Php | 0 Comments | Author: | 2195 clicks
A Data Type defines the kind of value a field (of a table) can contain. We have given a list of SQL Data Types with a short description in this page.
PHP Data Types : Arrays 10. 8. 2008 in Php | 0 Comments | Author: | 2576 clicks
An array in PHP is a collection of key/value pairs. This means that it maps values to keys. Array keys (or indexes) may be either an integers or a strings whereas values can be any type.
The round() method of math object is used to get the value of a number rounded to the nearest integer. If the fractional part of the number is greater than or equal to .5, the argument is rounded to the next higher integer. If the fractional part of number is less than .5, the argument is rounded to the next lower integer. | <urn:uuid:3b8db1d7-f73b-4a68-8e3e-8bc447a34821> | 2.65625 | 316 | Content Listing | Software Dev. | 85.978448 | 95,631,375 |
Whenever and wherever plates are sensitometrically tested, the purpose is usually to find a correct hypersensitisation time for a new batch of emulsion. Using a sensitometer and a densitometer, primary information is measured: Fog level, speed at fixed density and gamma. From them, the astronomer will derive other information such as hypersensitisation time (or baking temperature...) and exposure time, using a rule of thumb, such as “the optimum fog density level is 0.3 diffuse”.
KeywordsPhotographic Plate Large Telescope Detective Quantum Efficiency Schmidt Telescope Monodisperse Emulsion
Unable to display preview. Download preview PDF.
Bibliography of interest
A.A.S. Photo Bulletin
- Furenlid I., Schoening W.E. and Carder B.E. Jr.: A method of determining photographic SIN (issue # 16, p 14 )Google Scholar
- Hoag. A.A.: Sensitometer calibration (Issue #13, p.14)Google Scholar
- Hoag A.A., Furenlid I. and Schoening W.E.: Think S/N ! (Issue#19,p.3)Google Scholar
- Latham D.W. and Furenlid I.: The Influence of Background Exposure on the DOE of Photographic Plates (Issue #11, p. 11)Google Scholar
- Latham D.W.: Measurements of Interobservatory Densitometer Calibration Plates Issue # 18, p. 3)Google Scholar
The Messenger — E.S.O.
- Quebatte J., Dumoulin B. and R.M. West: Grid processing of large photographic plates (Issue # 46, p. 7 )Google Scholar
Astronomy with Schmidt type telescope (Ed. M. Cappacioli 1 Reidel Publishing Company Volume 110 Astrophysics and Science Library Photography
- Malin F.D.: The detection of faint images against the sky background (p. 57)Google Scholar
- Maury A.J.D.: Remarks on Tgrain technology applied to astrophotography (p.141) Instruments (Space Schmidt telescopes)Google Scholar
- Angel J.R.P.: Implementation and use of wide fields in future very large telescopes (p.549)Google Scholar
- Lemaitre G.: Optical design with the Schmidt concept (p.533)Google Scholar
Modern Techniques in Astronomical Photography 1978 (West and Heudier/ESO)
Astronomical Photography 1981 (Heudier and Sim/INAG)
- Llebaria A. & Figon P.: A general analytic formula for a film characteristic (p. 25)Google Scholar | <urn:uuid:7db387f6-a1a9-47a0-9cd0-e8bbc2cfbd1b> | 2.9375 | 570 | Academic Writing | Science & Tech. | 50.983468 | 95,631,393 |
Calculating the cubic space inside a three-dimensional object is the same process as calculating its volume. Another way to think of it is: How much liquid, air or solid could this object hold if it were hollowed out? Or, how much space does this object take up? The calculations involved are relatively simple--so long as you know the height, width and length of the rectangle or square, or the radius or diameter of the sphere in question--although you may find a calculator to be a useful aid.
Squares and Rectangles
Measure or calculate the height of the item in question.
Measure or calculate the width of the item in question. Measure in the same unit of measurement (e.g. inches, feet, meters, yards) as you used to measure the height.
Measure or calculate the length of the item in question. Again, use the same unit of measurement for length as you did for width and height.
Multiply all three measurements together. The order in which you do so does not matter. For example, if you were measuring the cubic space inside a rectangle that is 5 inches high, 6 inches wide and 10 inches long, you have an answer of 5 * 6 * 10 = 300 cubic inches.
Measure or calculate the radius of the sphere in question. If you know the diameter of the sphere, you can get the radius by dividing the diameter in two. If you know the sphere’s circumference, you can divide that circumference by 2, then divide again by pi, to get the circle’s radius.
Cube the circle’s radius. In other words, multiply it by itself three times. So if your circle has a radius of 3 inches, 3 cubed would be 3 * 3 * 3 = 9 inches cubed.
Multiply the result from Step 2 by 4/3. To continue our example we have 9 * 4/3 = 12.
Multiply the result from Step 3 by pi. The end result is the volume of the sphere. To conclude our example, we have 12 * pi = 37.699.
The approximate value of pi is 3.14. If you don't have a scientific calculator capable of inputting a more exact value of pi, substituting 3.14 for pi is almost always acceptable. | <urn:uuid:195f48cb-7346-41e2-8cb4-1dd27ed7aa85> | 4.40625 | 475 | Tutorial | Science & Tech. | 68.414051 | 95,631,405 |
is gathering strength in the waters to the east of the U.S. Mariana Islands, and is a serious threat to strike Guam and the nearby islands as a major typhoon on Friday morning (U.S. EDT.) The 8 am EDT Wednesday advisory from the Joint Typhoon Warning Center (JTWC)
put Dolphin's winds at 105 mph, and the Japan Meteorological Agency estimated a central pressure of 965 mb.
The latest 00Z Wednesday run of the European
model and 06Z run of the GFS model
show Dolphin passing within 50 miles of Guam between 06 - 09 UTC Friday (2 am - 5 am U.S. Eastern Daylight Time.) Satellite loops
show that Dolphin significantly increased in organization on Wednesday morning, with an increase in the intensity and areal coverage of its heavy thunderstorms and formation of an eye. Sea surface temperatures (SSTs) are near 29°C (84°F), and warm waters extend to great depth along Dolphin's track, giving it plenty of heat energy to draw upon for intensification. Wind shear
has risen over the past day to the moderate range, 10 - 20 knots, and is expected to remain low to moderate through Friday. Dolphin should be able to intensify to Category 3 typhoon status by the time it reaches Guam, and may rapidly intensify, potentially affecting Guam as a Category 4 super typhoon. Guam will likely be the last land area Dolphin will affect, as a strong trough of low pressure should recurve the storm to the north out to sea late this weekend. The GFS model is also advertising that a tropical disturbance near the Equator in the waters southeast of Guam (95W)
will organize early next week into a tropical depression, but it is too early to be confident of this prediction.Figure 1.
Typhoon Dolphin as seen by the MODIS instrument on NASA's Aqua satellite at approximately 03 UTC May 13, 2015. At the time, Dolphin had sustained winds of 85 mph, and a "pinhole" eye with a diameter of only six miles. Image credit: NASA Worldview.The last typhoon on Guam: thirteen years ago
The last typhoon to strike Guam was Typhoon Pongsona
, which hit the island as a Category 4 super typhoon with 150 mph winds on December 8, 2002. Sustained winds of 144 mph with gusts to 173 mph were recorded on the island, and Andersen Air Force Base was in the eye for two hours. The lowest pressure on Guam was 935 millibars, making Pongsona the third most intense typhoon to strike the island (the others: a 1900 typhoon with a 926 mb pressure, and Typhoon Karen of 1962, at 932 mb). With strong building standards and experience from repeated typhoon strikes (six typhoons in the previous ten years), there was one death from flying glass, and 193 injuries. Damage was over $700 million (2002 US$, $918 million 2015 USD), making Pongsona among the five costliest typhoons on the island. The typhoon also caused heavy damage on Rota and elsewhere in the Northern Mariana Islands, and as a result of its impact, the name Pongsona was retired. The last tropical storm to affect Guam was Tropical Storm Saomai of August 2006, which had 50 mph winds when it moved over the island. Figure 2.
Super Typhoon Pongsona as seen on December 8, 2002. At the time, Pongsona was at its peak strength--Category 4 with 150 mph winds. The image shows Pongsona over the Northern Mariana Islands in the western Pacific Ocean approaching Guam. Image credit: Jacques Descloitres, MODIS Rapid Response Team, NASA/GSFC - http://visibleearth.nasa.gov/view_rec.php?id=4761A record early start to typhoon season
May is exceptionally early for Guam to be worrying about a typhoon; according to NOAA's Historical Hurricane Tracks website
, no typhoon has affected the island in the months of February through June since record keeping began in 1945 (one January storm, Typhoon Roy of 1988, did pass near Guam in January, though.) Guam's early typhoon worries this year reflect how crazy-busy the early part of the 2015 typhoon season has been. The Japan Meteorological Agency (JMA) gave Tropical Storm Dolphin its name on May 9. According to statistics from the Japan Meteorological Agency's database from 1951 - 2015 maintained by Digital Typhoon,
this was the earliest appearance on record of the Northwest Pacific's seventh named storm of the year. The previous record was May 19, 1971
(Carla.) Usually by this time of year, just two named storms have appeared; the seventh storm of the year typically doesn't form until the third week of July. According to Colorado State University hurricane scientist Phil Klotzbach
, the seven storms so far in 2015 have been unusually strong: Northwest Pacific Accumulated Cyclone Energy (ACE) was at record high through May 11 (78.1), just ahead of the old record of 77.7 in 1957. The early and violent start to 2015 typhoon season is due, in part, to exceptionally warm ocean temperatures in the typhoon breeding region between 5 - 10°N near the Date Line. These temperatures have been over 2°C (3.6°F) above average in recent months, due to a strengthening El Niño event.
Storm chaser Jim Edds is on Guam, and will be documenting the impact of Dolphin on the island via his Twitter feed. | <urn:uuid:58398a99-2e50-48fa-80de-a1352032c8ee> | 2.71875 | 1,150 | Personal Blog | Science & Tech. | 60.064242 | 95,631,412 |
Dr Hanna of the University´s Department of Geography, alongside some of the World´s leading Greenland glaciologists and climatologists, analysed a combination of key meteorological and glaciological records spanning a number of decades as part of the research.
The findings, published in Journal of Climate, show how the Greenland Ice Sheet responded to more regional, rather than global, changes in climate between the 1960s and early 1990s. However the last fifteen years has seen an increase in ice melting and a striking correspondence of Greenland with global temperature variations, demonstrating Greenland´s recent response to global warming.
Summer 2003 was exceptionally warm around the margins of the Greenland Ice Sheet, which resulted in the second-highest meltwater running off from the Ice Sheet of the last 50 years. Summer 2005 experienced a record-high melt, which was very recently superseded in summer 2007 – a year almost as warm as 2003.
The team of researchers includes some of the leading Greenland glaciologists and climatologists from the Free University of Brussels, University of Colorado, Danish Meteorological Institute and NASA Goddard Earth Science and Technology Center, University of Maryland Baltimore County, as well as four members of the University of Sheffield.
Dr Edward Hanna said: "Our work shows that global warming is beginning to take its toll on the Greenland Ice Sheet which, as a relict feature of the last Ice Age, has already been living on borrowed time and seems now to be in inexorable decline. The question is can we reduce greenhouse-gas emissions in time to make enough of a difference to curb this decay?"
Lindsey Bird | EurekAlert!
New research calculates capacity of North American forests to sequester carbon
16.07.2018 | University of California - Santa Cruz
Scientists discover Earth's youngest banded iron formation in western China
12.07.2018 | University of Alberta
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
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Bacteria, which reciprocally exchange amino acids, stabilize their partnership on two-dimensional surfaces and limit the access of non-cooperating bacteria to the exchanged nutrients. Scientists at the Max Planck Institute for Chemical Ecology and the Friedrich Schiller University in Jena have shown that bacteria, which do not actively contribute to metabolite production, can be excluded from the cooperative benefits. The research team demonstrated that cooperative cross-feeding interactions that grow on two-dimensional surfaces are protected from being exploited by opportunistic, non-cooperating bacteria. (The ISME Journal, December 2015)
In natural microbial communities, different bacterial species often exchange nutrients by releasing amino acids and vitamins into their growth environment, thus feeding other bacterial cells. Even though the released nutrients are energetically costly to produce, bacteria benefit from nutrients their bacterial partners provide in return.
Amino acid measurements: Concentrations are high in the vicinity of cooperative bacteria (above). In contrast, no amino acids were detectable in areas surrounding non-cooperative bacteria (below).
S. Pande, F. Kaftan / Max Planck Institute for Chemical Ecology, S. Lang / Friedrich Schiller University Jena
Hence, this process is a cooperative exchange of metabolites. Scientists at the Max Planck Institute for Chemical Ecology and the Friedrich Schiller University in Jena have shown that bacteria, which do not actively contribute to metabolite production, can be excluded from the cooperative benefits. The research team demonstrated that cooperative cross-feeding interactions that grow on two-dimensional surfaces are protected from being exploited by opportunistic, non-cooperating bacteria.
Under these conditions, non-cooperating bacteria are spatially excluded from the exchanged amino acids. This protective effect probably stabilizes cooperative cross-feeding interactions in the long-run. (The ISME Journal, December 2015)
The Research Group “Experimental Ecology and Evolution” headed by Dr. Christian Kost is investigating how cooperative interactions between organisms have evolved. In this context, the scientists study a special type of division of labor that is very common in nature, namely the reciprocal exchange of nutrients among unicellular bacteria. For these tiny organisms it is often advantageous to divide the labor of certain metabolic processes rather than performing all biochemical functions autonomously. Bacteria that engage in this cooperative exchange of nutrients can save a significant amount of energy.
Indeed, in a previous study, the researchers could already demonstrate that this division-of-metabolic-labor can positively affect bacterial growth. In the new study, they addressed the question how such cooperative interactions can persist if non-cooperating bacteria consume amino acids without providing nutrients in return. The evolutionary disadvantage that results for cooperative cells could lead to a collapse of the cross-feeding interaction.
To experimentally verify this possibility, the scientists have monitored co-cultures of cooperating and non-cooperating bacteria. For this, they genetically engineered “cooperators” of two bacterial species that released increased amounts of certain amino acids into their environment. “As a matter of fact, non-cooperators grew better than cooperators in a well-mixed liquid medium, because under these conditions, they had an unrestricted access to the amino acids in the medium. Their growth, however, was considerably reduced when placed on a two-dimensional surface,” said Kost, summarizing the results of the experiments. A more detailed analysis revealed that non-cooperating bacteria could only exist at the very fringe of colonies consisting of cooperating bacteria.
For their study the scientists combined different methods and techniques. The basis formed a new research approach called “synthetic ecology”, in which certain mutations are rationally introduced into bacterial genomes. The resulting bacterial mutants are then co-cultured and their ecological interactions analyzed. In parallel, colleagues at the Friedrich Schiller University from the Department of Bioinformatics developed computer models to simulate these interactions. Finally, chemical analyses using mass spectrometric imaging was instrumental for visualizing the bacterial metabolites. Only the combination of microbiological methods with chemical-analytic approaches and computer simulations enabled the scientists to understand and elucidate this phenomenon.
“The fact that such a simple principle can effectively stabilize such a complex interaction suggests that similar phenomena may play important roles in natural bacterial communities,” Christian Kost states. After all, bacteria occur predominantly in so-called biofilms – these are surface-attached slime layers that consist of many bacterial species. Known examples include bacteria causing dental plaque or bacterial communities that are used in wastewater treatment plants. Moreover, biofilms are highly relevant for medical research: They do not only play important roles for many infectious diseases by protecting bacterial pathogens from antibiotics or the patients’ immune responses, but are also highly problematic when colonizing and spreading on the surfaces of medical implants.
This new study has elucidated that cooperating bacteria form cell clusters and in this way exclude non-cooperating bacteria from their community. “The importance of this mechanism is due to the fact that no complicated or newly-evolved condition, such as the recognition of potential cooperation partners, needs to be fulfilled to effectively stabilize this long-term partnership. Two cooperating bacterial strains and a two-dimensional surface are sufficient for this protective effect to occur”, explains Kost.
The study raises many new exciting questions the researchers plan to address in the future. For example, they are interested in whether or not similar synergistic effects occur when more than two bacterial partners are involved. In their natural habitats, it is likely that more than two bacterial species participate in such cooperative interactions, leading to rather complex interaction networks. Moreover, amino acid-producing bacterial mutants were synthetically generated for this study. Whether also naturally evolved “cooperators” that occur in a habitat like soil show similar dynamics, remains to be verified. Given that bacteria frequently occur in biofilms, cooperative cross-feeding is probably much more widespread than previously thought. Understanding the factors and mechanisms that promote or inhibit bacterial growth could thus provide important clues on how to fight harmful bacteria or to better use beneficial ones. [CK/AO]
Pande, S., Kaftan, F., Lang, S., Svatoš, A., Germerodt, S., Kost, C. (2015). Privatization of cooperative benefits stabilizes mutualistic cross-feeding interactions in spatially structured environments. The ISME Journal. DOI:10.1038/ismej.2015.212
Dr. Christian Kost, Max Planck Institute for Chemical Ecology, Hans-Knöll-Straße 8, 07745 Jena, Germany, Tel. +49 3641 57-1212, E-Mail firstname.lastname@example.org
Contact and Media Requests:
Angela Overmeyer M.A., Max Planck Institute for Chemical Ecology, Hans-Knöll-Str. 8, 07743 Jena, +49 3641 57-2110, E-Mail email@example.com
Download high-resolution images via http://www.ice.mpg.de/ext/downloads2015.html
http://www.ice.mpg.de/ext/1051.html?&L=0 (Division of Labor in the Test Tube, Press Release, December 2, 2013)
http://www.ice.mpg.de/ext/experimental-evolution.html (Research Group Experimental Ecology and Evolution)
Angela Overmeyer | Max-Planck-Institut für chemische Ökologie
NYSCF researchers develop novel bioengineering technique for personalized bone grafts
18.07.2018 | New York Stem Cell Foundation
Pollen taxi for bacteria
18.07.2018 | Technische Universität München
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
13.07.2018 | Event News
12.07.2018 | Event News
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18.07.2018 | Materials Sciences
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Time marches relentlessly forward for you and me; watch a movie in reverse, and you’ll quickly see something is amiss. But from the point of view of a single, isolated particle, the passage of time looks the same in either direction. For instance, a movie of two particles scattering off of each other would look just as sensible in reverse – a concept known as time reversal symmetry.
Now the BaBar experiment at the Department of Energy's (DOE) SLAC National Accelerator Laboratory has made the first direct observation of a long-theorized exception to this rule.
Digging through nearly 10 years of data from billions of particle collisions, researchers found that certain particle types change into one another much more often in one way than they do in the other, a violation of time reversal symmetry and confirmation that some subatomic processes have a preferred direction of time.
Reported this week in the journal Physical Review Letters, the results are impressively robust, with a 1 in 10 tredecillion (1043) or 14-sigma level of certainty – far more than needed to declare a discovery.
“It was exciting to design an experimental analysis that enabled us to observe, directly and unambiguously, the asymmetrical nature of time,” said BaBar collaborator Fernando Martínez-Vidal, associate professor at the University of Valencia and member of the Instituto de Fisica Corpuscular (IFIC), who led the investigation. “This is a sophisticated analysis, the kind of experimental work that can only be done when an experiment is mature.”
BaBar, which collected data at SLAC from 1999 to 2008, was designed to tease out subtle differences in the behavior of matter and antimatter that might help account for the preponderance of matter in the universe. It produced almost 500 million pairs of particles called B mesons and their antimatter counterparts B-bar mesons for study. BaBar scientists found that B mesons and B-bar mesons do, indeed, behave differently in ways that violate so-called CP symmetry, which incorporates the symmetries of charge (positive versus negative) and parity (which can be thought of as left-handedness versus right-handedness). This discovery of CP violation contributed to the 2008 Nobel Prize in Physics.
CP symmetry is linked with time reversal symmetry through the CPT (charge-parity-time) Theorem, which states that the three symmetries must remain in balance for any given particle system. If one of the symmetries is out of whack, at least one of the others must be, too.
So the BaBar data, with its evidence of CP symmetry violation already in hand, was a good place to look for violation of time reversal symmetry that would serve to balance CPT as a whole.
BaBar's new time violation analysis was based on a concept proposed in 1999. Researchers examined a chain of particle transformations in which B mesons flipped between two different states called B-zero and B-even. Taking advantage of the quantum entanglement of the B mesons, which enables information about the first decaying particle to be used to determine the state of its partner at the time of the decay, they were able to find that these transformations happened six times more often in one direction than the other.
“This is a fresh way to understand data we had already used to measure CP violation,” said BaBar physics coordinator Abner Soffer, associate professor at Tel Aviv University. “By looking at it slightly differently we were able to undeniably see time violation as well. What’s nice is that the effect was there the whole time, but nobody had thought about it the right way before.”
Time violation had previously been seen in particles called neutral kaons by the CPLEAR experiment at CERN, but that measurement was not direct because of the inability to distinguish T violation from CP violation, and the interpretation of those results drew some criticism. It’s hard to set up laboratory conditions that can see time reversal violation, Martínez-Vidal explained. But BaBar provided just the right conditions for a clear, direct measurement.
“In the past, a true test of time reversal symmetry with unstable particles was considered to be impossible,” said BaBar associate José Bernabéu, a professor at the University of Valencia and IFIC, and one of the originators of the analysis concept. “It's spectacular that the solution came from the same entanglement phenomenon used for quantum communication and computing.”
Michael Roney, BaBar spokesperson and professor at the University of Victoria in Canada, said "BaBar's data has been extremely fruitful and continues to produce important results, such as this unique and unambiguous test of quantum field theory. As we continue to work on almost 100 measurements from BaBar that investigate the fundamental nature of time and matter, we're gratified to have further validated this underlying theory."
This work is supported by the DOE Office of Science and NSF (USA), NSERC (Canada), CEA and CNRS-IN2P3 (France), BMBF and DFG (Germany), INFN (Italy), FOM (The Netherlands), NFR (Norway), MES (Russia), MINECO (Spain), STFC (United Kingdom). Individuals have received support from the Marie Curie EIF (European Union), the A. P. Sloan Foundation (USA) and the Binational Science Foundation (USA-Israel).
SLAC is a multi-program laboratory exploring frontier questions in photon science, astrophysics, particle physics and accelerator research. Located in Menlo Park, California, SLAC is operated by Stanford University for the U.S. Department of Energy Office of Science. To learn more, please visit www.slac.stanford.edu.
DOE’s Office of Science is the single largest supporter of basic research in the physical sciences in the United States, and is working to address some of the most pressing challenges of our time. For more information, please visit science.energy.gov.
Bronwyn Barnett | EurekAlert!
What happens when we heat the atomic lattice of a magnet all of a sudden?
18.07.2018 | Forschungsverbund Berlin
Subaru Telescope helps pinpoint origin of ultra-high energy neutrino
16.07.2018 | National Institutes of Natural Sciences
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
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This example shows how you can avoid a common mistake often made by people inexperienced with regular expressions. As an example, we will try to build a regular expression that can match any floating point number. Our regex should also match integers and floating point numbers where the integer part is not given. We will not try to match numbers with an exponent, such as 1.5e8 (150 million in scientific notation).
At first thought, the following regex seems to do the trick: [-+]?[0-9]*\.?[0-9]*. This defines a floating point number as an optional sign, followed by an optional series of digits (integer part), followed by an optional dot, followed by another optional series of digits (fraction part).
Spelling out the regex in words makes it obvious: everything in this regular expression is optional. This regular expression considers a sign by itself or a dot by itself as a valid floating point number. In fact, it even considers an empty string as a valid floating point number. If you tried to use this regex to find floating point numbers in a file, you'd get a zero-length match at every position in the string where no floating point number occurs.
Not escaping the dot is also a common mistake. A dot that is not escaped matches any character, including a dot. If we had not escaped the dot, both 4.4 and 4X4 would be considered a floating point numbers.
When creating a regular expression, it is more important to consider what it should not match, than what it should. The above regex indeed matches a proper floating point number, because the regex engine is greedy. But it also match many things we do not want, which we have to exclude.
Here is a better attempt: [-+]?([0-9]*\.[0-9]+|[0-9]+). This regular expression matches an optional sign, that is either followed by zero or more digits followed by a dot and one or more digits (a floating point number with optional integer part), or that is followed by one or more digits (an integer).
This is a far better definition. Any match must include at least one digit. There is no way around the [0-9]+ part. We have successfully excluded the matches we do not want: those without digits.
We can optimize this regular expression as: [-+]?[0-9]*\.?[0-9]+.
If you also want to match numbers with exponents, you can use: [-+]?[0-9]*\.?[0-9]+([eE][-+]?[0-9]+)?. Notice how I made the entire exponent part optional by grouping it together, rather than making each element in the exponent optional.
Finally, if you want to validate if a particular string holds a floating point number, rather than finding a floating point number within longer text, you'll have to anchor your regex: ^[-+]?[0-9]*\.?[0-9]+$ or ^[-+]?[0-9]*\.?[0-9]+([eE][-+]?[0-9]+)?$. You can find additional variations of these regexes in RegexBuddy's library.
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Nebula is included in the Wikipedia CD Selection, see Nebula at Schools Wikipedia. Please maintain high quality standards; if you are an established editor your last version in the article history may be used so please don't leave the article with unresolved issues, and make an extra effort to include free images, because non-free images cannot be used on the DVDs.
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Lord Rosse discovers that many of the nebulae have a spiral structure. He and John Herschel were at odds over the nature of nebulae, with Rosse believing they were unresolved clusters of stars. (The contention was related to the theory of evolution, with Rosse not believing that new stars were still forming.)
In 1900, Cornelius Easton argued that the Milky Way had a spiral structure and that many of the nebulae formed part of this structure. (This had first been suggested in the middle of the 19th century.)
The observations of E. E. Barnard lent weight to the idea that the dark regions of the sky were actually obscuring matter (rather than tunnel-like holes suggested by John Herschel).
The 1920 Shapley–Curtis Debate that would lead to the categorization of many nebulae as Island Universes (or galaxies) per Edwin Hubble.
Max Wolf was the first person to estimate the distance to interstellar clouds. His approximation compared the number of stars per square degree (and their magnitudes) in a cloud region to elsewhere.
In 1927, Herman Zanstra determined how the neutral hydrogen in H II regions became excited.
The 1927 explanation by Ira Sprague Bowen of the forbidden lines in the O III spectrum within nebula. (Previously attributed to "nebulium".) | <urn:uuid:7f71bef2-6c8f-48d4-8927-1ab30e33fcec> | 4 | 398 | Knowledge Article | Science & Tech. | 43.514283 | 95,631,479 |
A first evaluation of the spatial gradients in δ18Orecorded by European Holocene speleothems
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|McDermott et al GPC Revised Jan 2011_.pdf||1.42 MB||Adobe PDF||Download|
|Title:||A first evaluation of the spatial gradients in δ18Orecorded by European Holocene speleothems||Authors:||McDermott, Frank
Fairchild, Ian J.
Baldini, Lisa M.
Mattey, David P.
|Permanent link:||http://hdl.handle.net/10197/3697||Date:||Dec-2011||Abstract:||Oxygen isotope data for well dated Holocene speleothems from Europe have been compiled for the first time. The data were analysed at 1 ka time slices through the Holocene by taking averages of 50 year duration. After filtering the data to exclude high altitude, high latitude and sites proximal to the Mediterranean Sea, the data exhibit surprisingly tight linear correlations between speleothem O isotope values and longitude. The slope of the data on δ18O vs. longitude plots changes systematically from the early to the late Holocene, exhibiting a much steeper zonal gradient in the early Holocene. Changes in the isotope gradient through the course of the Holocene reflect both a gradual increase in δ18O in speleothems from the western margin of the transect and a simultaneous decrease in speleothem δ18O on the eastern end of the transect. These changes follow summer insolation trends through most of the Holocene, but show marked deviations from c. 4 ka to the present day. Steeper early Holocene zonal isotope gradients are attributed primarily to a combination of early Holocene warming in the west and intense convective rainfall over the European continent in summer time driven by high early Holocene summer insolation. Although the absolute δ18O values preserved in speleothems do not precisely reflect the equilibrium values with respect to the waters from which they are precipitated, the tight isotope-longitude correlations indicate that speleothems are reliable recorders of combined rainfall O isotope signals and air temperature.||Funding Details:||Science Foundation Ireland||Type of material:||Journal Article||Publisher:||Elsevier||Copyright (published version):||2011 Elsevier B.V.||Keywords:||Speleothems;Oxygen isotopes;Isotope gradients;Holocene;Climate Change;Palaeoclimate||Subject LCSH:||Speleothems
|DOI:||10.1016/j.gloplacha.2011.01.005||Language:||en||Status of Item:||Peer reviewed|
|Appears in Collections:||Earth Sciences Research Collection|
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This item is available under the Attribution-NonCommercial-NoDerivs 3.0 Ireland. No item may be reproduced for commercial purposes. For other possible restrictions on use please refer to the publisher's URL where this is made available, or to notes contained in the item itself. Other terms may apply. | <urn:uuid:583401e2-ce06-4419-8e75-27e67443d0db> | 2.6875 | 673 | Academic Writing | Science & Tech. | 33.43 | 95,631,481 |
Largest-Ever Undersea Landslide Revealed on Great Barrier Reef
The largest underwater landslide, along the slope bordering the famous Great Barrier Reef, has been discovered by an international group of scientists. The ancient remains, known as the Gloria Knolls Slide, were discovered about 45 miles off the coast of Queensland, Australia. The researchers modeled a potential tsunami for a sudden undersea mass failure of this scale, yielding a wave elevation of about 85 feet. More seabed mapping and sampling is needed to determine the timing at which the submarine landslides occurred. "The oldest fossil corals recovered off the top of the knoll were 302,000 years old - which means the landslide event that caused these knolls must be older," says lead researcher Dr. Angel Puga-Bernabéu of the University of Granada. The research was a collaborative effort between James Cook University, University of Sydney, University of Granada, University of Edinburgh, and the Australian Nuclear Science and Technology Organization. | <urn:uuid:723ab21b-3dba-4519-8fa4-0739e824b70b> | 3.5625 | 202 | Truncated | Science & Tech. | 24.898418 | 95,631,483 |
What is relative dating in science cold case video dating
Before the advent of absolute dating methods in the twentieth century, nearly all dating was relative.The main relative dating method is stratigraphy (pronounced stra-TI-gra-fee), which is the study of layers of rocks or the objects embedded within those layers.Sometimes, scientists already know the age of the fossil because fossils of the same species have been found elsewhere and it has been possible to establish accurately from those when the dinosaur lived.Geologists call this the principle of lateral continuity.Dating techniques are procedures used by scientists to determine the age of an object or a series of events.The two main types of dating methods are relative and absolute. Enter from in chronological order, from oldest to most recent, the letter corresponding to processes A through H below.Use upper case letters and insert one letter per box).
This feature is produced by changes in deposition over time.The Age of Dinosaurs was so many millions of years ago that it is very difficult to date exactly.Scientists use two kinds of dating techniques to work out the age of rocks and fossils. This considers the positions of the different rocks in sequence (in relation to each other) and the different types of fossil that are found in them.Relative dating methods are used to determine only if one sample is older or younger than another.Absolute dating methods are used to determine an actual date in years for the age of an object.
Paleontologists still commonly use biostratigraphy to date fossils, often in combination with paleomagnetism and tephrochronology. | <urn:uuid:3428dd96-1ede-40f0-9ded-e6664629b51b> | 3.65625 | 327 | Knowledge Article | Science & Tech. | 33.606012 | 95,631,485 |
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Foundress: a female founder, a group or organization created by a female.
Harvest: gather materials, usually food. Farmers harvest their crops at the end of each growing season.
Regurgitate: to vomit partially digested food. Birds and some other animals feed their young regurgitated food.
In nests of honey-pot ants, living food jars up to about half an inch across cling to the ceilings of underground cavities. On the surface, they are best recognized by their erratic, stop-and-go movements.
As with most types of ants, adult workers feed immature larvae by regurgitating liquid food. Honey-pot species take that two steps further. Workers forage outside the nest for plant juices and other foods, then feed sweet liquid to a specialized group of adult workers called "repletes." The repletes swell into berry-like spheres to store honey for sustaining the colony through the lean season. They hold up to eight times their body weight in honey, but can barely move.
Ant fan Ray Mendez savors them on crackers. "The flavor depends on what the foragers eat," said Mendez, who keeps a honey-pot ant farm in his southeastern Arizona home. "When we give them apples to eat, they taste just like apples," he said.
Pictured below to the right are seed harvesters found in back yards and deserts. The two, formerly cooperative foundresses of the ant species Messor pergandei, are engaged in lethal combat.
Such fights begin soon after the first adult workers appear in the nest and result in the demise of all but one of the original foundresses.
"Pogo" workers grow to about half an inch and range from red to black. They forage up to about 100 feet from their nests, which are conspicuous bare-soil circles with a central opening.
Queens may live more than 20 years, continuing to lay eggs from a single mating flight. But once individual workers begin foraging outside the nest, lizards, birds, dehydration or other hazards are likely to kill them within a month. Younger workers are continually tending new batches of eggs. As workers get older, they become expendable foragers instead of larva-tenders.
Tens of thousands of ants may cooperate as a single colony. Winged reproductive forms, males and virgin queens, fly after summer rains. After mating, the males promptly die and the queens try to start their own colonies. A tiny percentage succeed.
These shiny ants, either black or red, are common in yards and pack a nasty sting. Most are only about one-eighth of an inch long.
The Arizona Department of Agriculture has so far been successful at keeping Arizona free of the local fire ants' South American cousins, red imported fire ants, which have infested states from Florida to Texas.
The sickle-blade jaws of slave maker ants aren't good for feeding their own young, just for killing other ants and stealing their babies.
A newly mated slave maker queen rushes a nest of another species of ants. Often, that colony's workers kill her before she gets to their mother. If not, she kills their queen, then rubs herself with the scent from the dead queen. Then the workers act like she's their mother, and tend the eggs she lays and the larvae they hatch into. When those larvae mature into slave maker workers, they raid other colonies. They kill the adults and bring home the eggs and young to keep up a supply of slaves in their mom's colony.
Army ants attack other ants' nests not to steal babies, but to eat them. The ones in and around the Valley are nearly blind. Tens of thousands of them may form raiding columns during nighttime raids, eating whatever other insects they come across. An Army ant colony does not build a permanent nest. It moves as a group from place to place to find new food supplies, using temporary shelters such as rodent holes.
Dr. Biology. (2010, January 07). Arizona Ant Species. ASU - Ask A Biologist. Retrieved July 16, 2018 from https://askabiologist.asu.edu/arizona-ant-species
Dr. Biology. "Arizona Ant Species". ASU - Ask A Biologist. 07 January, 2010. https://askabiologist.asu.edu/arizona-ant-species
Dr. Biology. "Arizona Ant Species". ASU - Ask A Biologist. 07 Jan 2010. ASU - Ask A Biologist, Web. 16 Jul 2018. https://askabiologist.asu.edu/arizona-ant-species | <urn:uuid:f440354b-cb62-4c66-a240-486314df6d0e> | 3.15625 | 978 | Knowledge Article | Science & Tech. | 61.248869 | 95,631,524 |
This article will cover the methods for managing kernel modules.
The Template:Codeline command handles the addition and removal of modules from the Linux kernel.
To manually load (or add) a module, run:
# modprobe module_name
Occasionally you could need to remove (or unload) a module; in this case use the following command:
# modprobe -r module_name
# rmmod module_name
The Template:Filename directory can be used to pass module settings to udev. You can use configuration files with any name in the directory, but Template:Filename is the defacto standard for general settings.
Blacklisting when referring to Kernel modules is a mechanism to stop the kernel module loading. This is either when the associated hardware is not required to be used, or loading that module causes problems.
For example there may be a two kernel modules, that if they get loaded together try to control the same piece of hardware resulting in a conflict.
Some modules are loaded as part of the initramfs. Template:Codeline will print out all autodetected modules. To avoid initramfs from loading those modules you wish to blacklist, then blacklist them in Template:Filename. Running Template:Codeline will list all modules pulled in by the various hooks (i.e. filesystem hook, SCSI hook, etc). Remember to rebuild initramfs once you've blacklisted the modules.
Using files in Template:Filename
You can blacklist modules using the Template:Codeline keyword:
Alternatively, one can force nothing to be installed to "blacklist" that module and any that depend on it:
Using kernel command line
You can also blacklist modules on the kernel command line using the following syntax:
The "blacklist" option blacklists modules loaded by that name only. But if some other module depends on that module, that module will get loaded because blacklisting does not match dependent modules.
The following commands can help determine the dependencies of a module from the module itself.
- Format the contents of Template:Filename and show what kernel modules are currently loaded:
$ modinfo MODULE_1
- Use Template:Codeline to show information about Template:Codeline (including aliases and install commands):
$ modprobe --show-depends MODULE_2 | <urn:uuid:a76b88ae-230e-4edf-bc94-6e9f9e63b81f> | 2.578125 | 480 | Tutorial | Software Dev. | 22.844973 | 95,631,530 |
Amphibians are at home in water, but can they also sense volatile compounds in the air? “Indeed they can,” reports Stefan Schulz. Working with colleague Miguel Vences and Ph.D. students Dennis Poth and Katharina Wollenberg at the University of Brunswick, he has found volatile pheromones in frogs from Madagascar. In the journal Angewandte Chemie, the scientists have now introduced various natural compounds that the frogs apparently use for communication.
“Anuran amphibians communicate primarily by means of acoustic, optical, and tactile signals,” explains Schulz. “In addition, they also seem to communicate through peptides and proteins that easily dissolve in water or on the water’s surface. There have recently been indications that frogs may also respond to volatile signal compounds.”
Schulz and his co-workers have now examined frogs from Madagascar (Mantellidae), a very species-rich family of frogs from the rainforests. The males of one subspecies, the Mantellinae, form large characteristic glands on the undersides of their rear shanks.
In the glands of the frog Mantidactylus multiplicatus, the researchers found two volatile main components, and demonstrated that the frogs react to both substances. One of the components is an alcohol, the other a macrolide, a ring-shaped molecule with an intramolecular ester group.
It is related to phoracantholide J, a component of the defensive secretion of the Australian beetle Phoracantha synonyma. However, the spatial arrangement of the atoms is different: the frog macrolide is the mirror image of the beetle molecule. For identification purposes, Schulz’s team developed a new synthetic route for the production of phoracantholide J that delivers enantiomerically pure products, either only the original version or the mirror image. Their method is also less complicated than earlier approaches.
The researchers found similar macrolides in the glands of related frogs. For example, in the species Gephyromantis boulengeri, they discovered a previously unknown macrolide that they named gephyromantolid A. “In fact, volatile compounds are widespread among the Mantellinae, but occur in species-specific mixtures,” says Schulz. “The volatile compounds could play a previously underrated role in species recognition over short distances in these very species-rich communities.”
This could explain the extreme degree of species diversity of frogs in the tropical rainforest. With over 100 species per region in Madagascar, chemical recognition of species could help to avoid failed pairings that lead to nonviable offspring. Such macrolides could thus have a significant influence on the speciation and evolution of tropical amphibians.About the Author
Angewandte Chemie International Edition, Permalink to the article: http://dx.doi.org/10.1002/anie.201106592
Stefan Schulz | Angewandte Chemie
Barium ruthenate: A high-yield, easy-to-handle perovskite catalyst for the oxidation of sulfides
16.07.2018 | Tokyo Institute of Technology
The secret sulfate code that lets the bad Tau in
16.07.2018 | American Society for Biochemistry and Molecular Biology
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
16.07.2018 | Physics and Astronomy
16.07.2018 | Life Sciences
16.07.2018 | Earth Sciences | <urn:uuid:5271297c-45cd-4747-8c1c-276f2beb9074> | 3.640625 | 1,280 | Content Listing | Science & Tech. | 33.887263 | 95,631,531 |
The sky on Pluto is blue. NASA just sent home the pictures.
Oh, and there’s water, too. Frozen, but still water.
The latest NASA photos rewrite the book on Pluto yet again, adding planet-like details about the little body that had its planet-ness stripped away by hard-hearted astronomers in 2006.
So, could Pluto make a planetary comeback?
It’s probably a long shot, but the first colour photos of the haze around Pluto have certainly surprised space veterans.
“Who would have expected a blue sky in the Kuiper Belt? It’s gorgeous,” said a NASA statement quoting Alan Stern, principal scientist for the New Horizons probe that reached Pluto this summer.
Stern happens to be one of the few who still sees Pluto as a planet.
New Horizons took a lot of photos as it sped past Pluto, and has been sending them back gradually, as its power allows.
What arrived a few days ago is a view with Pluto backlit by the sun, which lights up the thin atmosphere. Scientists think the actual particles in the haze are red or grey. But they scatter light — that is, they split apart white light — in such a way that an observer sees blue.
The image isn’t a simple photo. It’s computer-generated using software that tries to reproduce colours the way the human eye would perceive them.
We couldn’t breathe that blue sky, though. It’s methane and nitrogen, with little sooty particles.
Water ice is also visible on the surface, and space explorers are always glad to find that. Water would be a valuable resource for future space travellers, both for drinking and because it can be split into oxygen and hydrogen.
Water ice isn’t everywhere. Many parts of Pluto seem to be covered by ice formed from other frozen gases.
Stern is still making arguments that Pluto is fundamentally a planet, not just a chunk of rock like most objects in the cold, distant Kuiper Belt: It is rounded by its own gravity; it has an atmosphere; and it has mountains, flat plains and ridges that suggest active geological processes.
But for now it’s still officially a dwarf planet. Pretty sky, though. Maybe some day someone will write a song about it. | <urn:uuid:61cce436-d330-459c-809a-baad6e0b9194> | 3.234375 | 483 | News Article | Science & Tech. | 61.700318 | 95,631,543 |
Even if all three barriers are damaged, the nuclear fuel will not dissolve into the groundwater, according to a new doctoral dissertation from Chalmers University of Technology.
By Midsummer it will be announced where Sweden's spent nuclear fuel will be permanently stored. Ahead of the decision a debate is underway regarding how safe the method for final storage is, primarily in terms of the three barriers that are intended to keep radioactive material from leaking into the surrounding groundwater.
But according to the new doctoral dissertation, uranium would not be dissolved by the water even if all three barriers were compromised.
"This is a result of what we call the hydrogen effect," says Patrik Fors, who will defend his thesis in nuclear chemistry at Chalmers on Friday. "The hydrogen effect was discovered in 2000. It's a powerful effect that was not factored in when plans for permanent storage began to be forged, and now I have shown that it's even more powerful than was previously thought."The hydrogen effect is predicated on the existence of large amounts of iron in connection with the nuclear fuel. In the Swedish method for final storage, the first barrier consists of a copper capsule that is reinforced with iron. The second barrier is a buffer of bentonite clay, and the third is 500 meters of granite bedrock. Some other countries have chosen
to make the first barrier entirely of iron.
It is known that microorganisms and fissure minerals in the rock will consume all the oxygen in the groundwater. If all three barriers were to be damaged, the iron in the capsule would therefore be anaerobically corroded by the water, producing large amounts of hydrogen. In final storage at a depth of 500 meters, a pressure of at least 5 megapascals of hydrogen would be created.
Patrik Fors has now created these conditions in the laboratory and examined three different types of spent nuclear fuel. All of the trials showed that the hydrogen protects the fuel from being dissolved in the water, even though the highly radioactive fuels create a corrosive environment in the water as a result of their radiation. The reason for the protective effect is that the hydrogen prevents the uranium from oxidizing and converting to liquid form.
Furthermore, the hydrogen makes the oxidized uranium that already exists as a liquid in the water shift to a solid state. The outcome was that the amount of uranium found dissolved in the water, after experiments lasting several years, was lower than the natural levels in Swedish groundwater."The hydrogen effect will prevent the dissolution of nuclear fuel until the fuel's radioactivity is so low that it need no longer be considered a hazard," says Patrik Fors. The amount of iron in the capsules is so great that it would produce sufficient hydrogen to protect the fuel for tens of
thousands of years.
Patrik Fors carried out his experiments at the Institute for Transuranium Elements in Karlsruhe, Germany, in a joint project with Chalmers. The institute is operated by the European Commission. The research was also funded by SKB, the Swedish Nuclear Fuel and Waste Management Company.
The dissertation "The effect of dissolved hydrogen on spent nuclear fuel corrosion" will be publicly defended on April 24 at 10 a.m. Place: Hall KE, Chemistry Building, Kemigården 4, Chalmers University of Technology, Gothenburg, Sweden.For more information, please contact:
Sofie Hebrand | idw
Upcycling of PET Bottles: New Ideas for Resource Cycles in Germany
25.06.2018 | Fraunhofer-Institut für Betriebsfestigkeit und Systemzuverlässigkeit LBF
Dry landscapes can increase disease transmission
20.06.2018 | Forschungsverbund Berlin e.V.
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
16.07.2018 | Physics and Astronomy
16.07.2018 | Life Sciences
16.07.2018 | Earth Sciences | <urn:uuid:74ce7096-87e2-4748-a2e3-d9eae7d02839> | 3.65625 | 1,344 | Content Listing | Science & Tech. | 42.290423 | 95,631,546 |
Prior to the turn of the 20th century, hunters engaged in a holiday tradition known as the Christmas "Side Hunt." They would choose sides and go afield with their guns—whoever brought in the biggest pile of feathered (and furred) quarry won.
Conservation was in its beginning stages in that era, and many observers and scientists were becoming concerned about declining bird populations. Beginning on Christmas Day 1900, ornithologist Frank M. Chapman, an early officer in the then-nascent Audubon Society, proposed a new holiday tradition—a "Christmas Bird Census" that would count birds during the holidays rather than hunt them.
So began the Christmas Bird Count. Thanks to the inspiration of Chapman and the enthusiasm of 27 dedicated birders, 25 Christmas Bird Counts were held that day. The locations ranged from Toronto, Ontario to Pacific Grove, California with most counts in or near the population centers of northeastern North America. Those original 27 Christmas Bird Counters tallied around 90 species on all the counts combined.
CBC in the Modern Era
Each November, birders interesting in participating in the CBC can sign up and join in through the Audubon website. From December 14 through January 5 each year tens of thousands of volunteers throughout the Americas brave snow, wind, or rain, and take part in the effort. Audubon and other organizations use data collected in this long-running wildlife census to assess the health of bird populations, and to help guide conservation action.
How the Christmas Bird Count Helps Protect Species and Their Habitat
The data collected by observers over the past century allow Audubon researchers, conservation biologists, wildlife agencies and other interested individuals to study the long-term health and status of bird populations across North America. When combined with other surveys such as the Breeding Bird Survey, it provides a picture of how the continent's bird populations have changed in time and space over the past hundred years.
The long term perspective is vital for conservationists. It informs strategies to protect birds and their habitat, and helps identify environmental issues with implications for people as well.
What conservationists have learned through Christmas Bird Count data
- Audubon’s 2014 Climate Change Report is a comprehensive, first-of-its kind study that predicts how climate change could affect the ranges of 588 North American birds. Of the 588 North American bird species Audubon studied, more than half are likely to be in trouble. Our models indicate that 314 species will lose more than 50 percent of their current climatic range by 2080.
- The Environmental Protection Agency (EPA) has included Audubon's climate change work from CBC data as one of 26 indicators of climate change in their 2012 report.
- In 2009 CBC data were instrumental in the collaborative report by the North American Bird Conservation Initiative, U.S. Fish & Wildlife Service - State of the Birds 2009.
- In 2007, CBC data were instrumental in the development of Audubon’s Common Birds in Decline Report, which revealed that some of America's most beloved and familiar birds have taken a nosedive over the past forty years.
Imminent Threat to Greater Sage-Grouse
Tell Congress to oppose a harmful rider that threatens sage-grouse and other wildlife.
Defend the Migratory Bird Treaty Act
Tell Congress and the Department of the Interior to uphold the country's most important bird protection law.
Get Audubon in Your Inbox
Let us send you the latest in bird and conservation news. | <urn:uuid:f0d6ecfc-6859-459b-8e41-71e389f1e4b6> | 4.03125 | 718 | About (Org.) | Science & Tech. | 41.325694 | 95,631,558 |
The Solar Longitude (Abbrev: S.L., λ ☉) is 216 degrees, this value is the the date of maximum activity. It is measured as a degree with zero degree indicating spring equinox (roughly March 21st/22nd). 90 is the Summer Solstice, 180 is the Autumn Equinox and 270 is the Winter Solstice. This degree is independent of the calender. AMS .
The source of the meteor shower is 2P/Encke. The closest star to the radiant point of the meteor shower is Ushakaron. The coordinates can also be determined by the Right Ascension (47.9) and the Declination (12.8).
The Zenith Hourly Rate or how many you expect to see during the hour is 5. The ZHR can radically increase if the comet or associated object is close by. The speed/velocity of the Meteor Shower particles is 27 km/s. The population index of the meteor shower is 2. The population index refers to the magnitude distribution of the meteorites, the smaller the index, the brighter the meteors are, the higher, the dimmer the meteors are. For this particular meteor shower, faint meteors are more frequent.
|Closest Star to Radiant Point||Ushakaron|
|Max Activity Date||05 Nov|
|Activity Period||Sept 17-Nov 27|
|Solar Longitude / λ ☉||216 °|
|Zenith Hourly Rate||5| | <urn:uuid:f8a18afa-e299-42c5-ab85-33375bc8251a> | 2.65625 | 316 | Knowledge Article | Science & Tech. | 63.025096 | 95,631,561 |
Physicists tackle long-standing question using novel experimental approach
Scientists from the University of Göttingen and the Jülich Research Centre have made an important step towards a deeper understanding of metal-semiconductor interfaces. By means of a novel experimental approach the researchers investigated the distribution of the electronic charge at these interfaces on the atomic scale. Their results were published in the journal Physical Review Letters and highlighted as “Editors’ suggestion”.
In every electronic semiconductor device the interfaces between two different materials play a crucial role. In this context, the atomic and electronic structure of metal-semiconductor interfaces is of fundamental im-portance.
For the development and the design of novel nanometer-sized devices, a basic understanding of these interfaces is of central interest. However, up until now, no commonly accepted model that describes metal-semiconductor interfaces in their entirety existed. This is also due to the fact that scientists did not have an adequate experimental approach to investigate the atomic structure of these interfaces.
Now scientists in Göttingen and Jülich investigated the technologically interesting iron/gallium arsenide inter-face using a scanning tunneling microscope developed in Göttingen. “By scanning a very sharp metal tip across the interface we were able to simultaneously map its structure and its electronic properties on the atomic scale,” explains doctoral candidate Tim Iffländer from Göttingen University’s IV. Physical Institute.
“In combination with theoretical calculations from the colleagues in Jülich we found out that the electronic barrier between metal and semiconductor, on the one hand, is dominated by charges from the metal tailing into the semiconductor and, on the other hand, essentially depends on the chemical bonds between metal and semiconductor as well.”
“The high level of agreement between measured and calculated charge distribution at the interface demon-strates that our experimental approach is particularly well-suited to study the electronic properties of metal-semiconductor interfaces on the atomic scale,” adds Dr. Martin Wenderoth, head of the research group. “This allows us to check the relevance of several theoretical models.
Moreover, our experiment serves as starting point for further studies addressing the influence of defects and the detailed atomic structure at the interface on the electronic properties of metal-semiconductor contacts.”
Original publication: T. Iffländer et al. Local Density of States at Metal-Semiconductor Interfaces: An Atomic Scale Study. Phys. Rev. Lett. 114, 146804 (2015). Doi: 10.1103/PhysRevLett.114.146804 .
Dr. Martin Wenderoth
University of Göttingen
Faculty of Physics – IV. Physical Institute
Friedrich-Hund-Platz 1, 37077 Göttingen
Phone +49 551 39-9367 or -4536
Romas Bielke | idw - Informationsdienst Wissenschaft
Further reports about: > Electronic > Physical Review Letters > atomic scale > atomic structure > chemical bonds > electronic properties > experimental > gallium arsenide > metal-semiconductor contacts > scanning tunneling microscope > semiconductor > semiconductor device > structure > theoretical calculations
What happens when we heat the atomic lattice of a magnet all of a sudden?
18.07.2018 | Forschungsverbund Berlin
Subaru Telescope helps pinpoint origin of ultra-high energy neutrino
16.07.2018 | National Institutes of Natural Sciences
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
19.07.2018 | Materials Sciences
19.07.2018 | Earth Sciences
19.07.2018 | Life Sciences | <urn:uuid:dafbb9d3-4cd1-451b-ad84-4cef1f50992e> | 2.625 | 1,317 | Content Listing | Science & Tech. | 28.600031 | 95,631,569 |
The Solar Longitude (Abbrev: S.L., λ ☉) is 33.6 degrees, this value is the the date of maximum activity. It is measured as a degree with zero degree indicating spring equinox (roughly March 21st/22nd). 90 is the Summer Solstice, 180 is the Autumn Equinox and 270 is the Winter Solstice. This degree is independent of the calender. AMS .
The source of the meteor shower is 26P/Grigg-Skjellerup. The closest star to the radiant point of the meteor shower is Ahadi. The coordinates can also be determined by the Right Ascension (110.4) and the Declination (-45.1).
The Zenith Hourly Rate or how many you expect to see during the hour is Var. The ZHR can radically increase if the comet or associated object is close by. The speed/velocity of the Meteor Shower particles is 15 km/s. The population index of the meteor shower is 2. The population index refers to the magnitude distribution of the meteorites, the smaller the index, the brighter the meteors are, the higher, the dimmer the meteors are. For this particular meteor shower, faint meteors are more frequent.
|Closest Star to Radiant Point||Ahadi|
|Max Activity Date||23 Apr|
|Activity Period||Apr 15 - Apr 28|
|Solar Longitude / λ ☉||33.6 °|
|Zenith Hourly Rate||Var| | <urn:uuid:5b19cfef-e1e2-4e71-abe6-645e176b4147> | 2.671875 | 322 | Knowledge Article | Science & Tech. | 65.121229 | 95,631,570 |
PlantTracker data from 2012 onwards
CitationNature Locator (2017). PlantTracker data from 2012 onwards. Occurrence dataset https://doi.org/10.15468/8y4bie accessed via GBIF.org on 2018-07-22.
DescriptionDistribution and abundance data on 16 high priority non-native, invasive plant species primarily from across the UK. These are largely riparian or aquatic species and comprise the following: Japanese Knotweed (Fallopia japonica) Himalayan Balsam (Impatiens glandulifera) Orange Balsam (Impatiens capensis) Water Fern (Azolla filiculoides) New Zealand (Pigmyweed Crassula helmsii) Parrota^??s Feather (Myriophyllum aquaticum) Giant Hogweed (Heracleum mantegazzianum) Floating Pennywort (Hydrocotyle ranunculoides) Creeping Water-primrose (Ludwigia peploides) Piri-piri burr (Acaena novae-zelandiae) American Skunk-cabbage (Lysichiton americanus) Rhododendron (Rhododendron ponticum) Monkey Flower (Mimulus guttatus, M. luteus & hybrids) Curly Waterweed (Lagarosiphon major) Gunnera spp (Gunnera spp) Pampas Grass (Cortaderia selloana)
PurposeThe project was originally conceived to provide the Environment Agency with a clearer picture of the UK distribution of the 16 target species and to engage the general public with data collection but it has now expanded encompass many other users including Scottish Natural Heritage, Scottish Environment Protection Agency, Jersery Government among others.
Quality ControlData quality high. 90% of records have a photograph attached and those without are validated based on recorder credentials. Geolocation accuracy high.
- Data is collected using a smartphone application (see http://planttracker.naturelocator.org/ for further information and links to download the app). Data is collected by both experts and interested members of the public in the field. Critically, each record collected is verifiable since it is usually comprised of a photograph along with other relevant metadata. If a photo is missing records are accepted by other supporting information (text description) or reputation of the recorder. Records are also accurately geo-located since the app utilises the phone’s inbuilt GPS capabilities, often resolving the location to a matter of metres. The app also contains a built-in photographic ID guide to aid users. Data collected by the PlantTracker App is being stored in the Indicia community data warehouse, hosted by the Biological Records Centre. Data is verified by experienced botanists using the iRecord system.
UK primarily (It has been recognised that data collected from the entire British Isles are valuable to data users. Equally, records from Europe may also be important so no attempt is made to limit its use within Europe). Accuracy of records - normal range 3-20m
Broadway Business Centre, 32a Stoney Street, Lace Market
administrative point of contact | <urn:uuid:642186ba-20bd-4be3-ab07-346ac5b6a426> | 2.796875 | 659 | Structured Data | Science & Tech. | 13.658784 | 95,631,612 |
HUGE NUMBERS OF JELLYFISH SWARM IN UK'S SUMMER SEAS
HUGE NUMBERS OF JELLYFISH SWARM IN UK’S SUMMER SEAS MCS urges beach goers and sea users to take part in a national survey as barrel, moon, compass, blue and lion’s mane jellyfish swarm in our seas.
HUGE NUMBERS OF JELLYFISH SWARM IN UK’S SUMMER SEAS MCS urges beach goers and sea users to take part in a national survey as barrel, moon, compass, blue and lion’s mane jellyfish swarm in our seas. Fascinating to some and frightening to most, jellyfish numbers appear to be on the increase in UK seas, with the recent shut down of Scotland’s Torness nuclear power station directly due to swarms of moon jellyfish blocking the water intake cooling systems. As the UK’s seas continue to warm up over the summer, more jellyfish blooms are expected, and as the nation prepares for the summer holidays, MCS is urging beach goers and sea users to take part in their national jellyfish survey. “The jellyfish survey is an excellent way for people to get involved in finding out more about our threatened seas. There is strong evidence that jellyfish numbers are increasing around the world, including UK seas, and these increases have been linked to factors such as pollution, over-fishing and possibly climate change,” says MCS’s Peter Richardson. “We should consider jellyfish populations as important indicators of the state of our seas, and the MCS jellyfish survey helps provide some of the information we need to understand more about them.” Taking part in the jellyfish survey is easy! The full-colour MCS jellyfish photo-ID guide can be downloaded and jellyfish encounters can also be reported in detail online here. Already, some areas of the UK’s seas resemble a ‘jellyfish soup’, such as the Irish Sea where large numbers of moon, lion’s mane, blue and compass jellyfish have already been reported. “Most jellyfish bloom in summer, but some species can survive the cool winter months too,” says MCS Biodiversity Programme Manager Peter Richardson, “This year, we received our first reports of the huge but harmless barrel jellyfish off North Wales back in early January, and this species has occurred in huge numbers in the Irish Sea and beyond ever since, with reports received from North Somerset to the Firth of Clyde. Since May we have also received reports of large numbers of several other species of jellyfish from various coastal all sites round the UK - it is another good year for the jellyfish!” MCS aims to understand more about where and when jellyfish occur around the UK though their survey. While encouraging beach lovers and coastline visitors to report their findings, MCS also warns to ‘look but not touch’ as some jellyfish can sting - particularly the lion’s mane that is swarming in huge numbers at some coastal sites in the north west. Jellyfish are the staple diet of critically endangered leatherback turtles, seasonal visitors to UK seas, which migrate from their tropical nesting beaches to feed on our abundant seasonal jellyfish blooms. Examinations of dead leatherbacks stranded on UK shores have revealed that they feed on several species of British jellyfish. By comparing the distribution of jellyfish with environmental factors such as sea temperature, plankton production and current flow, we hope to understand what influences the seasonal distribution of jellyfish and leatherbacks in UK waters. This year there have been three confirmed leatherback sightings since June, all spotted in waters off western UK where jellyfish blooms have been reported. Over 6000 jellyfish encounters have been reported since the MCS Survey was launched in 2003. The survey data is being analysed in collaboration with the University of Exeter and early results of the public sightings show interesting differences in the distribution of the larger jellyfish species around Britain.
Actions you can take
Did you know?…
Over 60% of the population of Wales either live or work on the coast.
It is not unusual for turtle to frequent Welsh shores feeding on jellyfish
Basking shark can be spotted feeding on plankton in Welsh waters
Help protect 40% of English seas
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Authors: Fran De Aquino
Devices that collect water from the atmospheric air using condensation are well-known. They operate in a manner very similar to that of a dehumidifier: air is passed through a cooled coil, making water to condense. This is the most common technology in use. Here, we present a device that can collect a large amount of water (more than 1m3/s) from the atmospheric air using gravitational condensation. Another novelty of this device is that it consumes little electricity. In addition, the new technology of this device leads to a new concept of pump, the Gravitational Pump, which can be used to pump water at very low cost from aquifers, rivers, lakes, etc., and also to supply the high pressure (100atm or more) needed to push seawater through the semipermeable membrane, in the desalinization process known as reverse osmosis.
Comments: 4 Pages.
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public class LineWordReader extends java.lang.Object implements WordReader, java.io.Serializable
WordReaderthat considers each line of a document a single word.
The intended usage of this class is that of indexing stuff like lists of document
identifiers: if the identifiers contain nonalphabetical characters, the default
FastBufferedReader might do a poor job.
Note that the non-word returned by
next(MutableString, MutableString) is
|Modifier and Type||Method||Description|
Returns a copy of this word reader.
Extracts the next word and non-word.
Resets the internal state of this word reader, which will start again reading from the given reader.
public boolean next(MutableString word, MutableString nonWord) throws java.io.IOException
If this method returns true, a new non-empty word, and possibly
a new non-word, have been extracted. It is acceptable
that the first call to this method after creation
or after a call to
WordReader.setReader(Reader) returns an empty
word. In other words both
nonWord are maximal.
word- the next word returned by the underlying reader.
nonWord- the nonword following the next word returned by the underlying reader.
public LineWordReader setReader(java.io.Reader reader) | <urn:uuid:c3d91d51-2c52-43c9-8c74-9d2e5db607aa> | 2.8125 | 291 | Documentation | Software Dev. | 46.491842 | 95,631,691 |
2 years ago6 views
A shark’s snout contains tiny pores, known as ampullae of Lorenzini, which can sense weak electric fields from prey. Now, new research indicates that a jelly inside the pores is a highly efficient proton conductor. According to Science News, sharks have a sixth sense that helps them locate prey in murky ocean waters. But the jelly is the best biological proton conductor discovered so far. | <urn:uuid:c250dea8-f114-4864-be00-cce4c5613b76> | 3.53125 | 89 | Truncated | Science & Tech. | 51.295357 | 95,631,700 |
Video: Planet Earth, The Living Machine. What is the Theory of Plate Tectonics? “It is a theory that describes the formation, movements, and interactions of earth’s plates.”. Video: Planet Earth, The Living Machine. How can the Grand Canyon reveal the history of the Earth?
What is the Theory of Plate Tectonics?
“It is a theory that describes the formation, movements, and interactions of earth’s plates.”
How can the Grand Canyon reveal the history of the Earth?
It’s rock layers show changes in time.
The oldest rocks are on the bottom and the youngest rocks are on the top.
Who was James Hutton? What was his big discovery?
The Earth is very old and the Earth is constantly changing.
James Hutton: The “Father of Geology”
Who was Alfred Wegener? What was his big idea?
Alfred Wegener was a meteorologist (person who studies weather.) He proposed the idea of continental drift.
Why was Alfred Wegener’s proclamation known as a hypothesis and not a theory?
Alfred Wegener did not have the experimental data to back up his findings.
What was Pangaea? How many millions of years ago did it start to exist and when did it start to break apart?
Pangaea means “all lands” connected together. It was a major landmass that started to break apart about 200 million years ago.
What did scientists discover in the middle of the Atlantic Ocean?
They discovered the mid-ocean ridge, a volcanic mountain chain.
What is seafloor spreading?
Seafloor spreading is when the ocean floor spreads apart (diverges) at a mid-ocean ridge.
How can rock samples record the magnetic field of the earth?
The magnetism (North or South orientation) of the planet is recorded in a rock when the lava hardens. It gives us insight into the past magnetic orientation of the Earth at different times.
What did Vine and Matthews discover on the Sea Floor at the Mid-Atlantic Ridge?
They discovered that there are alternating patterns of north and south the farther you get away from the Ridge. They also found that rocks get older as you go away from the Ridge.
How does the age of rock change the farther you go away from the Mid-Atlantic Ridge?
Rocks get older as you go away from the Mid-Atlantic Ridge.
What are 3 ways in which the Earth’s plates interact?
Plates can move towards each other (converge). Plates can move away from each other (diverge). Plates can slide past each other (transform).
What is subduction and what are the results of subduction?
Subduction is when one plate dives under another plate. The results of subduction are volcanoes and earthquakes.
How were the Himalaya mountains formed and what type of plate boundary were they formed upon?
The Himalayas were formed when the Indian Plate crashed into the Eurasian Plate. This is a convergent collision boundary.
What kind of plate boundary is the San Andreas Fault? In how many years will the San Francisco Giants and the Los Angeles Dodgers be cross-town rivals as a result of motion along this fault?
The San Andreas Fault is a transform (strike-slip) type of fault. It will take around 15 million years for the two baseball teams to become cross-town rivals.
What is thought to be the main driving force for plate tectonics in the asthenosphere and the lower mantle of the Earth?
The most accepted idea is mantle convection. Other ideas are ridge push and slab pull. Mantle Convection Animation #2
How were the Hawaiian Islands formed in the middle of the Pacific Plate?
The Hawaiian Islands were formed by a hot spot. This is when the Pacific Plate moves Northwest over the hot spot.
What happened in New Madrid, Missouri in 1812? How does this event give evidence of plate tectonics thousands of miles from the nearest plate boundary?
There was a very large earthquake. Originally, the plates were pulling apart here, forming the fault zone. Compressional forces now make this one of the most dangerous fault zones.
How do fossils and the finding of exotic terranes in the Marin Headlands near San Francisco support the theory of Micro-Plate Tectonics?
Fossils of animals and plants can be found many miles from their original place of origin. This means that they must have been carried along with the plates. We call these lands Exotic Terranes.
How did the shapes of continents shown by Christopher Scotese give rise to Alfred Wegener’s continental drift hypothesis? Explain.
Some of the continents are like puzzle pieces. They would fit together if you joined them.
How does the movement of continents influence the migration patterns of sea turtles to the Ascension Islands in the middle of the Atlantic Ocean? How is this evidence for natural selection within sea turtle species?
Sea turtles have to swim farther and farther out into the Atlantic Ocean to reach their breeding grounds on the Ascension Islands. Only the individuals strong enough to make the swim will evade jaguar predators and pass their traits off to offspring. | <urn:uuid:3b4a7307-1439-434c-ae30-5691cacf19dd> | 3.75 | 1,098 | Content Listing | Science & Tech. | 59.88831 | 95,631,721 |
A View from Emerging Technology from the arXiv
One-Third of Sun-Like Stars Have Earth-Like Planets In Habitable Zone
Astronomers have calculated the likelihood of finding Earth-like planets around other stars using the latest data from the Kepler mission.
The Kepler orbiting observatory is specifically designed to find Earth-like planets around nearby stars.
Earlier this year, the Kepler team released the mission’s first 136 days of data and it has turned out to be a veritable jackpot. In that time Kepler looked at some 150,000 target stars and found evidence for 1,235 potential exoplanets. That’s quite a haul.
Since then, most of the work on this database has been to identify the characteristics of all these exoplanets. But such a large dataset also allows for statistical analyses too, from which various projections can be made.
Today, Wesley Traub at the California Institute of Technology in Pasadena, reveals the results of just such a study. Traub has looked only at the stars that are most similar to the Sun, namely those with the classification F, G or K and worked out often various types of planets occur.
The results are straightforward to state. Traub says that mid-size planets are just as likely to be found around faint stars and bright ones. By contrast, far fewer small planets show up around faint stars. That’s almost certainly because small planets are more difficult for Kepler to see.
It’s also easier for Kepler to see planets that are closer to their stars because it looks for the tiny changes in brightness that these transits cause. That’s why almost a third of all Kepler’s detections orbit their star in less than 42 days. For the most part, these planets orbit too closely to be in the habitable zone.
What interests most astronomers is how many exoplanets orbit at a greater distance, inside the habitable zone. Most of these planets are too far away from their stars to have been picked up by Kepler yet. But Traub says his data analysis provides a way to work out how many their ought to be.
That’s because he’s found a power law that describes how the number of stars with a given orbital period. So all he has to do is assume a longer orbital period equivalent to being in the habitable zone to work out how many planets there ought to be at this distance.
Here’s the answer: “About one-third of FGK stars are predicted to have at least one terrestrial, habitable-zone planet,” he says.
So by this measure, there are plenty of other Earths out there.
Ref: arxiv.org/abs/1109.4682: Terrestrial, Habitable-Zone Exoplanet Frequency from Kepler
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Surface Area of Cube
In this section we will discuss Surface Area of Cube :
means the area required for making the cube. After unfolding it we get the area of each face. The total area of each face which is in square shape gives us the Surface area of cubical shape.
From the above figure, we can see that there are 6 faces and each face is of square shape.
Some solved examples on surface area of cube
| Surface area = 6 x (side )2 = 6a2
Lateral surface area = 4a2
Diagonal of Cube = (√3) a
1) Find the ratio of the total surface area and lateral surface area of a cube.
Total surface area of cube = 6 a2
Lateral surface area = 4 a2
∴ TSA / LSA = 6 a2
/ 4 a2
⇒ = 3 / 2
∴ The ratio is 3 : 2.
2) A 4 cm cube is cut into 1 cm cubes. Calculate the total surface area of all the small cubes.
TSA of big cube = 6 a2
= 6 x 42
= 96 cm2
TSA of small cube = 6 x 1 x 1 = 6 cm2
Number of new cubes 4 / 1 = 4
∴ TSA of all small cubes = 96 x 4 = 384 cm2
3) Each edge of a cube is increase by 50%. Find the percentage increase in the surface are of the cube.
Let the edge = a cm
So increase by 50 % = a + a/ 2 = 3a / 2
TSA of original cube = 6 a2
TSA of new cube = 6 ( 3a/ 2)2
= 6 x 9a2
/ 4 = 54a2
/ 4 = 13.5a2
Increase in area = 13.5a2
- 6 a2
Increase % = ( 7.5a2
/ 6 a2
) x 100 = 125%
4) Three equal cubes are placed adjacently in a row. Find the ratio of total surface area of the new rectangular prism ( cuboid ) to that of the sum of the surface areas of the three cubes.
TSA of cube = 6a2
Length of new rectangular prism = 3a , width = a and height = a
TSA of rectangular prism = 2( lw + wh + lh)
⇒ = 2 (3a x a + a x a + 3a x a)
⇒ = 2 ( 3a2
⇒ = 2 ( 7a2
TSA of rectangular prism = 14a2
∴ TSA of rectangular prism / TSA of a cube 3 cubes = (14a2
) / 18a2
∴ Ratio = 14 / 18 = 7 / 9
∴ The ratio is 7 : 9
Surface Area :
• Surface Area of Cube
• Surface Area of Rectangular Prism(Cuboid)
• Surface Area of Cylinder
• Surface Area of Cone
• Surface Area of Sphere and Hemisphere
• Surface Area of Prism
• Surface Area of Pyramid
From cube to Mensuration
From Cube to Home Page | <urn:uuid:402ba276-3b5d-4a4b-8192-39fe2b95edd9> | 4.0625 | 676 | Tutorial | Science & Tech. | 68.079959 | 95,631,725 |
The GHG Reservoir (G-res) tool allows companies, investors, consultants, decision-makers and other stakeholders to report on the carbon footprint of a reservoir.
Using readily available input data, the tool provides a cost effective way to more accurately assess net greenhouse gas (GHG) emissions.
The tool was developed by the International Hydropower Association (IHA) in collaboration with the UNESCO Chair for Global Environmental Change.
Reporting on the carbon footprint of reservoirs
When a reservoir is created, greenhouse gases may be released over time due to the decomposition of organic material in the flooded area. In other conditions, a reservoir may act as carbon sink: absorbing more emissions than it emits. Up until now, however, accurately assessing reservoir emissions has required large-scale and costly multi-year studies.
Assessing the net GHG emissions of a reservoir is now an expectation for sustainability reporting and a requirement for financing a hydropower project through climate finance.
How it works
The G-res tool uses a modelling methodology based on current scientific knowledge and over 500 empirical measurements from more than 200 reservoirs worldwide.
It builds on a conceptual framework developed in cooperation with researchers from the University of Quebec at Montreal (UQAM), the Norwegian Foundation for Scientific and Industrial Research (SINTEF) and the Natural Resources Institute of Finland (LUKE).
Using the tool
In cooperation with: | <urn:uuid:e617c2a6-0727-4c3f-93dc-fbe3ba1c849f> | 3.640625 | 285 | Knowledge Article | Science & Tech. | 14.761789 | 95,631,739 |
Researchers engineer bacteria to exhibit stochastic Turing patterns
First in-vivo proof of principle that patterns can be stabilized by noise
The mechanism of pattern formation in living systems is of paramount interest to bioengineers seeking to develop living tissue in the laboratory. Engineered tissues would have countless potential medical applications, but in order to synthesize living tissues, scientists need to understand the genesis of pattern formation in living systems.
A new study by researchers at the University of Illinois at Urbana-Champaign, the Massachusetts Institute of Technology, and the Applied Physics Laboratory, Johns Hopkins University has brought science one step closer to a molecular-level understanding of how patterns form in living tissue. The researchers engineered bacteria that, when incubated and grown, exhibited stochastic Turing patterns: a “lawn” of synthesized bacteria in a petri dish fluoresced an irregular pattern of red polka dots on a field of green.
What are classic Turing patterns?
Turing patterns can be stripes, spots or spirals that arise naturally out of a uniform state. In 1952, the British mathematician, computer scientist, and theoretical biologist Alan Turing proposed a mechanism for how patterns form, theorizing that it’s due to a very general kind of instability, which he worked out mathematically. At that time, biology had not yet uncovered the complexities of gene regulation, and it’s now clear that the model Turing proposed is overly simplified to describe the multitude of parameters at work in animal-skin pattern formation. So while Turing patterns have been observed in certain chemical reactions, such patterns have proven very difficult to demonstrate in biological organisms.
U of I Physics Professor Nigel Goldenfeld illustrates the limitations of classic Turing pattern formation in biology, using a predator-prey analogy.
“The problem with Turing’s mechanism,” Goldenfeld explains, “is that it hinges on a criterion that isn’t satisfied in many biological systems, namely that the inhibitor must be able to move much more quickly than the activator. For example, if instead of chemicals, we were looking at two creatures in an ecosystem, like wolves and sheep, the wolves would need be able to move around much faster than the sheep to get classic Turing patterns. What this would look like, you would first see the sheep grow in number, feeding the wolves, which would then also grow in number. And the wolves would run around and contain the sheep, so that you would get little localized patches of sheep with the wolves on the outside. That’s essentially the mechanism in animal terms for what Turing discovered.”
The stochastic Turing model is driven by randomness.
In the current study, the researchers demonstrated both experimentally and theoretically that Turing patterns do in fact occur in living tissues—but with a twist. Where the instability that generates the patterns in Turing’s model is defined as a high diffusion ratio between two chemicals, an activator and an inhibitor, in this study, researchers demonstrate that it’s actually randomness—which would in most experiments be considered background noise—that generates what Goldenfeld has coined a stochastic Turing pattern.
About a decade ago, Goldenfeld and a former graduate student, Dr. Tom Butler, developed a theory of stochastic Turing patterns, wherein patterns develop not from a high inhibitor-activator ratio, but from the noise of stochastic gene expression. Goldenfeld explains, “About 10 years ago we asked, what happens if there is only a small number of sheep, so that there are large fluctuations in population numbers? Now you get processes where sheep die at random. And we discovered, when you give birth to randomness, that actually drives the formation of stochastic Turing patterns. These are random patterns, but they have a very characteristic structure, and we worked out mathematically what that was.
“The theory of stochastic Turing patterns doesn’t require a great difference in speed between the prey and the predator, the activator and the inhibitor. They can be more or less the same, and you still get a pattern. But it won’t be a regular pattern. It’ll be disordered in some way.”
The bioengineering experiments
The original experimental and modeling work at MIT were led by Ron Weiss and carried out by David Karig, now at the Applied Physics Laboratory, Johns Hopkins University, and Ting Lu, now at the U of I, and later continued by graduate student Nicholas DeLateur at MIT.
Goldenfeld notes, “Serendipity definitely played a role in our connecting our two studies, as it often does in academia—the right place, the right time, and our ideas converged.”
Validating the stochastic Turing theory
To test if the experiments really were described by the new theory took several years of work. K. Michael Martini, a graduate student at the Center for the Physics of Living Cells at the U of I, worked with Goldenfeld to build a very detailed stochastic model of what was going on in these synthetic pattern-forming gene circuits, computed the consequences, and then compared the theoretical predictions with what the bioengineers had seen in the petri dishes.
“To really prove that our stochastic patterns work—it was hard. We had a lot of predictions we had made that had to be verified in experiment,” comments Goldenfeld. “Because the mathematics that describe these patterns have many parameters, we had to explore all of the effects of each. It involved a lot of searching in parameter space to reveal what was the mechanism of pattern formation. And there was necessarily a lot of interaction and collaboration with our engineering colleagues.
“What our work shows is that you can in fact get Turing patterns even in situations where you wouldn’t expect to be able to see them, but they are disordered patterns—stochastic Turing patterns. And the stochasticity here is not the birth and death of sheep or wolves, but it’s the birth and death, the creation and absorption of proteins. This is a very counter-intuitive prediction: It’s the noise of stochastic gene expression that generated these patterns. Normally you think of noise wiping out a signal. If you were trying to listen to music on radio, noise in the signal drowns it out. But in this case, we have a noise-stabilized pattern.”
These findings shed new light on an age-old question and begins to pave the way for future efforts in biomedical engineering.
Goldenfeld affirms, “This is really the first proof of principle that you can engineer in vivo stochastic Turing patterns, though it’s not simple. So now we know that this mechanism really can work, and that these fluctuations can drive patterns. Ultimately, bioengineers would like to use this type of technology to make novel tissues and new functional biological systems. Our study shows that you can do that in a regime where the classical Turing patterns couldn’t be used.”
These findings were published June 11, 2018, in the Proceedings of the National Academy of Sciences of the United States of America (PNAS), in the article “Stochastic Turing patterns in a synthetic bacterial population.”
This work was supported by the National Institutes of Health and the National Science Foundation (NSF), with additional support from the Independent Research and Development Program of the Johns Hopkins University Applied Physics Laboratory and from the Center for the Physics of Living Cells through NSF’s Physics Frontiers Center Program. The conclusions presented are those of the researchers and not necessarily those of the funding agencies. | <urn:uuid:9623e33e-5c58-4161-bcf5-1b781be40e10> | 3.546875 | 1,581 | News (Org.) | Science & Tech. | 33.823013 | 95,631,748 |
Photograph taken on October 1, 2004 of renewed volcanic activity within the crater formed by the eruption of Mount St. Helens in 1980. Recent activity, concentrated on the south side of the volcanic dome formed in the 1980s, includes uplift of a new dome from beneath the crater glacier and formation of vents by glacier melting and explosive eruptions of steam and ash. Credit: USGS
Elevation differences in the crater were found between two airborne LIDAR surveys conducted in September, 2003 and October 4, 2003. The image is a computer-generated representation of the October 4 topography. The superimposed colors indicate areas of change: areas where elevation has lowered between 0.5 to 30 meters (blue); areas where elevation has increased between 1.5 to 40 m, 40 m to 80 m, and 80 m to 120 m are green, yellow, and orange, respectively. Credit: USGS and NASA
U.S. Geological Survey (USGS) and NASA scientists studying Mount St. Helens are using high-tech Light Detection and Ranging (LIDAR) technology to analyze changes in the surface elevation of the crater, which began deforming in late September 2004.
With data derived from airborne LIDAR, scientists can accurately map, often in exquisite detail, the dimensions of the uplift and create better models to forecast volcanic hazards. LIDAR shows, in the two weeks before Oct. 4, the new uplift grew to the height of a 35-story building (110 meters or 360 feet) and the area of 29 football fields (130,000 square meters).
"This is the first time USGS and NASA have teamed to use LIDAR to measure volcano deformation," said USGS scientist Ralph Haugerud. He noted LIDAR technology enables researchers to compare with greater accuracy than ever before the topography before and after volcanic events. "The resulting pictures of topographic change can reveal information found in no other kind of data set," added David Harding, a scientist at NASA’s Goddard Space Flight Center, Greenbelt, Md.
Krishna Ramanujan | NASA
Scientists discover Earth's youngest banded iron formation in western China
12.07.2018 | University of Alberta
Drones survey African wildlife
11.07.2018 | Schweizerischer Nationalfonds SNF
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
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The brown bear (Ursus arctos) is considered an endangered species across Europe. While the species is largely extinct in the western part of the continent, larger populations have persisted in the eastern part, including Russia, the Carpathians and the Balkan Peninsula.
“Unfortunately, we lack considerable knowledge about these few remaining viable bear populations, including basic data such as population size and connectivity“, says Dr. Carsten Nowak, wildlife geneticist at Senckenberg. In order to change this unsatisfying situation, leading bear experts from the Balkani Research Society sampled more than 200 scat, hair and tissue samples of the species across Bulgarian bear habitats. Individual DNA profiles generated at the DNA laboratories of Senckenberg and the LOEWE Biodiversity and Climate Research Centre in Frankfurt (BiK-F) finally provided hard data on the population status in the country. During the analysis, however, PhD student Christiane Frosch revealed an unusual pattern: several individual profiles collected in three regions in the main mountain regions of the country, the Stara Planina Mountains and the Rhodopes, differed considerably from all the other bear profiles. Where did these bears come from and how did they get there?
The scientists finally found the place of origin of these „scientific problem bears“: Samples from the Carpathian mountains in Romania provided from bear conservationists of the local Milvus Group perfectly matched the unusual Bulgarian DNA profiles.These regions, however, lie several hundred kilometers apart from each other and the generally high genetic difference between the populations does not suggest high rates of exchange.
Although bears are good long-distance dispersers and could theoretically make it from Romania to Bulgaria by themselves, the scientists were skeptic. „We cannot exclude the possibility of natural migration, but geographic locations of the revealed samples and several other patterns make this scenario unlikely“, says Nowak.
Bear Hunting – a Dictator’s Hobby?
Intensive investigation and regional study finally brought a more reasonable explanation: during the era of socialism some Eastern European heads of government were passionate bear hunters. It is reported that the Romanian dictator, Nicolae Ceausescu (1918-1989), shot more than 1000 bears in his lifetime. The constant success of his bear hunting activities was guaranteed by numerous assistant hunters and game wardens, and by activities that targeted the boosting of the Romanian bear population, including raising bears in captivity.
Some of these bears were used for improving relationships with allied rulers. In Romania and Bulgaria people report that the large Carpathian bears were brought to Bulgarian enclosures be military planes and released in order to spice up the less impressive local bear population. Indeed, at least one of the places where translocated bears where kept, the Kormisosh enclosure in the Rhodopes, does still exist (see photo), as local investigations revealed. Indeed, several of the “alien” bear genotypes were found in the vicinity of this enclosure.
More than two decades after the breakdown of socialism in Eastern Europe researchers from Germany, Bulgaria and Romania confirm a curious legend: aerial dispersal is not restricted to plants, insects, spiders, or birds. Occasionally, this might also involve bears, the heaviest land predators on earth.
It should be noted that despite of intensive investigation, the researchers found no written documents about the case. Their study, now online in the journal “Conservation Genetics” is the first written document to certify it.
Nowak, C.; Domokos, C.; Dustov, A.; Frosch, C.: Molecular evidence for historic long-distance translocations of brown bears in the Balkan region; 2014, Conservation Genetics.
Dr. Carsten Nowak
Conservation Genetics Section
Senckenberg Field station Gelnhausen
Tel +49 (0) 6051-61954-3122
Senckenberg Gesellschaft für Naturforschung
Tel. +49 (0) 69- 7542 1434
Dr. Sören Dürr | Senckenberg
Colorectal cancer risk factors decrypted
13.07.2018 | Max-Planck-Institut für Stoffwechselforschung
Algae Have Land Genes
13.07.2018 | Julius-Maximilians-Universität Würzburg
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
13.07.2018 | Event News
13.07.2018 | Materials Sciences
13.07.2018 | Life Sciences | <urn:uuid:e169167b-ec35-4dec-8af0-ece59afd3290> | 3.3125 | 1,477 | Content Listing | Science & Tech. | 34.424433 | 95,631,752 |
Our genes decide about many things in our lives – what we look like, which talents we have, or what kind of diseases we develop. For a long time dismissed as “junk DNA”, we now know that also the regions between the genes fulfil vital functions. They contain a complex control machinery with thousands of molecular switches that regulate the activity of our genes. Until now, however, regulatory DNA regions have been hard to find. Scientists around Patrick Cramer at the Max Planck Institute (MPI) for Biophysical Chemistry in Göttingen and Julien Gagneur at the Technical University of Munich (TUM) have now developed a method to find regulatory DNA regions which are active and controlling genes.
The genes in our DNA contain detailed assembly instructions for proteins, the “workers” carrying out and controlling virtually all processes in our cells. To ensure that each protein fulfils its tasks at the right time in the right place of our body, the activity of the corresponding gene has to be tightly controlled.
This function is taken over by regulatory DNA regions between the genes, which act as a complex control machinery. “Regulatory DNA regions are essential for development in humans, tissue preservation, and the immune response, among others,” explains Patrick Cramer, head of the Department for Molecular Biology at the MPI for Biophysical Chemistry. “Furthermore, they play an important role in various diseases. For example, patients suffering from cancer or cardiovascular conditions show many mutations in exactly those DNA regions,” the biochemist says.
When regulatory DNA regions are active, they are first copied into RNA. “The resulting RNA molecules have a great disadvantage for us researchers though: The cell rapidly degrades them, thus they were hard to find until now,” reports Julien Gagneur, who recently moved with this group from the Gene Center of the Ludwig-Maximilians-Universität Munich to the TUM. “But exactly those short-lived RNA molecules often act as vital molecular switches that specifically activate genes needed in a certain place of our body. Without these molecular switches, our genes would not be functional.”
An anchor for short-lived molecular switches
Björn Schwalb and Margaux Michel, members of Cramer’s team, as well as Benedikt Zacher, scientist in Gagneur’s group, have now succeeded in developing a highly sensitive method to catch and identify even very short-lived RNA molecules – the so-called TT-Seq (transient transcriptome sequencing) method. The results are reported in the latest issue of the renowned scientific journal Science on June 3rd.
In order to catch the RNA molecules, the three junior researchers used a trick: They supplied cells with a molecule acting as a kind of anchor for a couple of minutes. The cells subsequently incorporated the anchor into each RNA they made during the course of the experiment. With the help of the anchor, the scientists were eventually able to fish the short-lived RNA molecules out of the cell and examine them.
“The RNA molecules we caught with the TT-Seq method provide a snapshot of all DNA regions that were active in the cell at a certain time – the genes as well as the regulatory regions between genes that were so hard to find until now,” Cramer explains. “With TT-Seq we now have a suitable tool to learn more about how genes are controlled in different cell types and how gene regulatory programs work,” Gagneur adds.
In many cases, researchers have a pretty good idea which genes play a role in a certain disease, but do not know which molecular switches are involved. The scientists around Cramer and Gagneur are hoping to be able to use the new method to uncover key mechanisms that play a role during the emergence or course of a disease. In a next step they want to apply their technique to blood cells to better understand the progress of a HIV infection in patients suffering from AIDS.
Björn Schwalb, Margaux Michel, Benedikt Zacher, Katja Frühauf, Carina Demel, Achim Tresch, Julien Gagneur, Patrick Cramer: TT-Seq maps the human transient transcriptome.
Science 352,1225-1228 (2016), doi: 10.1126/science.aad9841.
Prof. Dr. Patrick Cramer, Department of Molecular Biology
Max Planck Institute for Biophysical Chemistry, Göttingen
Phone: +49 551 201-2800
Prof. Dr. Julien Gagneur, Computational Biology Group
Technical University of Munich
Phone: +49 89 289-19411
Dr. Anne Morbach, Public Relations Office
Max Planck Institute for Biophysical Chemistry, Göttingen
Phone: +49 551 201-1308
http://www.mpibpc.mpg.de/15377790/pr_1620 – original press release
http://www.mpibpc.mpg.de/cramer – Website of the Department of Molecular Biology at the Max Planck Institute for Biophysical Chemistry, Göttingen
http://www.gagneurlab.in.tum.de – Website of the Computational Biology Group at the Technical University of Munich
Dr. Carmen Rotte | Max-Planck-Institut für biophysikalische Chemie
World’s Largest Study on Allergic Rhinitis Reveals new Risk Genes
17.07.2018 | Helmholtz Zentrum München - Deutsches Forschungszentrum für Gesundheit und Umwelt
Plant mothers talk to their embryos via the hormone auxin
17.07.2018 | Institute of Science and Technology Austria
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
17.07.2018 | Information Technology
17.07.2018 | Materials Sciences
17.07.2018 | Power and Electrical Engineering | <urn:uuid:5aa01e47-42d4-489a-b998-693bd903d106> | 3.484375 | 1,795 | Content Listing | Science & Tech. | 43.998109 | 95,631,789 |
The Bayon temple in Angkor Thom, Cambodia has shown serious deterioration and is subject to the formation of various pigmented biofilms. Because biofilms are damaging the bas-reliefs, low reliefs engraved on the surface of sandstone, information about the microbial community within them is indispensable to control biofilm colonization. PCR-denaturing gradient gel electrophoresis (DGGE) analysis of biofilm samples from the pigmented sandstone surfaces showed that the bacterial community members in the biofilms differed clearly from those in the air and had low sequence similarity to database sequences. Non-destructive sampling of biofilm revealed novel bacterial groups of predominantly Rubrobacter in salmon pink biofilm, Cyanobacteria in chrome green biofilm, Cyanobacteria and Chloroflexi in signal violet biofilm, Chloroflexi in black gray biofilm, and Deinococcus-Thermus, Cyanobacteria, and Rubrobacter in blue green biofilm. Serial peeling-off of a thick biofilm by layers with adhesive sheets revealed a stratified structure: the blue-green biofilm, around which there was serious deterioration, was very rich in Cyanobacteria near the surface and Chloroflexi in deep layer below. Nitrate ion concentrations were high in the blue-green biofilm. The characteristic distribution of bacteria at different biofilm depths provides valuable information on not only the biofilm formation process but also the sandstone weathering process in the tropics.
Mendeley saves you time finding and organizing research
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Washington: Harvard scientists have created a system that uses bacteria to convert solar energy into a liquid fuel.
The work integrates an "artificial leaf," which uses a catalyst to make sunlight split water into hydrogen and oxygen, with a bacterium engineered to convert carbon dioxide plus hydrogen into the liquid fuel isopropanol.
"This is a proof of concept that you can have a way of harvesting solar energy and storing it in the form of a liquid fuel," said Pamela Silver, Professor of Biochemistry and Systems Biology at Harvard Medical School (HMS).
"It's not like we're trying to make some super-convoluted system. Instead, we are looking for simplicity and ease of use," Silver said.
The artificial leaf invented by the paper's senior author, Daniel Nocera, Professor of Energy at Harvard University, depends on catalysts made from materials that are inexpensive and readily accessible.
"The catalysts I made are extremely well adapted and compatible with the growth conditions you need for living organisms like a bacterium," Nocera said.
In their new system, once the artificial leaf produces oxygen and hydrogen, the hydrogen is fed to a bacterium called Ralstonia eutropha.
An enzyme takes the hydrogen back to protons and electrons, then combines them with carbon dioxide to replicate - making more cells.
Next, based on discoveries made earlier by Anthony Sinskey, professor of microbiology and of health sciences and technology at The Massachusetts Institute of Technology (MIT), new pathways in the bacterium are metabolically engineered to make isopropanol.
The same principles could be employed to produce drugs such as vitamins in small amounts, Silver said.
The team's immediate challenge is to increase the bionic leaf's ability to translate solar energy to biomass by optimising the catalyst and the bacteria.
Their goal is 5 per cent efficiency, compared to nature's rate of 1 per cent efficiency for photosynthesis to turn sunlight into biomass.
The findings are published in the journal PNAS. | <urn:uuid:59f95bfd-77d1-40a2-b950-bf4396551838> | 3.8125 | 413 | News Article | Science & Tech. | 25.786346 | 95,631,841 |
Concentric crater fill
A concentric crater fill is a landform where the floor of a crater is mostly covered with a large number of parallel ridges. It is common in the mid-latitudes of Mars, and is widely believed to be caused by glacial movement. Areas on Mars called Deuteronilus Mensae and Protonilus Mensae contain many examples of concentric crater fill.
Concentric crater fill, like lobate debris aprons and lineated valley fill, is believed to be ice-rich. Sometimes boulders are found on concentric crater fill; it is believed they fell off the crater wall, then were transported away from the wall with the movement of the glacier. Erratics on Earth were carried by similar means.
High resolution pictures taken with HiRISE reveal that some of the surfaces of concentric crater fill are covered with strange patterns called closed-cell and open-cell brain terrain. The terrain resembles a human brain. It is believed to be caused by cracks in the surface accumulating dust and other debris, together with ice sublimating from some of the surfaces. The cracks are the result stress from gravity and seasonal heating and cooling.
Close-up view of concentric crater fill, as seen by HiRISE under HiWish program Note: this is an enlargement of previous image of a concentric crater. Location is Phaethontis quadrangle.
Wide-view of concentric crater fill, as seen by HiRISE. Location is the Casius quadrangle.
Well-developed hollows, as seen by HiRISE under the HiWish program. Location is the Casius quadrangle. Note: this is an enlargement of the previous image that was taken by CTX.
This series of drawings illustrates why researchers believe many craters are full of ice-rich material. The depth of craters can be predicted based upon the observed diameter. Many craters are almost full, instead of having bowl shape; hence it is believed that they have gained much material since they were formed by impact. Much of the extra material is believed to be ice that fell from the sky as snow or ice-coated dust.
Wide view of concentric crater fill, as seen by CTX Location is the Phaethontis quadrangle.
- Casius quadrangle
- Climate of Mars
- Deuteronilus Mensae
- Fretted terrain
- Impact crater
- Glaciers on Mars
- Protonilus Mensae
- Water on Mars
- Dickson, J. et al. 2009. Kilometer-thick ice accumulation and glaciation in the northern mid-latitudes of Mars: Evidence for crater-filling events in the Late Amazonian at the Phlegra Montes. Earth and Planetary Science Letters.
- "HiRISE - Concentric Crater Fill in the Northern Plains (PSP_001926_2185)". hirise.lpl.arizona.edu.
- Head, J. et al. 2006. Extensive valley glacier deposits in the northern mid-latitudes of Mars: Evidence for late Amazonian obliquity-driven climate change. Earth Planet. Sci Lett: 241. 663-671.
- Levy, J. et al. 2007. Lineated valley fill and lobate debris apron stratigraphy in Nilosyrtis Mensae, Mars: Evidence for phases of glacial modification of the dichotomy boundary. J. Geophys. Res.: 112.
- Levy, J. et al. 2009. Concentric crater fill in Utopia Planitia: History and interaction between glacial "brain terrain" and periglacial processes. Icarus: 202. 462-476.
- Marchant, D. et al. 2002. Formation of patterned ground and sublimation till over Miocene glacier ice in Beacon valley, southern Victorialand, Antarctica. Geol. Soc. Am. Bull:114. 718-730.
- Head, J. and D. Marchant. 2006. Modification of the walls of a Noachian crater in northern Arabia Terra (24E, 39N) during mid-latitude Amazonian glacial epochs on Mars: Nature and evolution of lobate debris aprons and their relationships to lineated valley fill and glacial systems. Lunar Planet. Sci: 37. Abstract # 1126.
- Mellon, M. 1997. Small-scale polygonal features on Mars: Seasonal thermal contraction cracks in permafrost. J. Geophysical Res: 102. 25,617-625,628.
- Ley, J. et al. 2009. Concentric crater fill in Utopia Planitia: History and interaction between glacial "brain terrain" and periglacial processes. Icarus: 202. 462-476. | <urn:uuid:c3a15974-8cd2-45b1-b891-c027986c775c> | 4.25 | 1,007 | Knowledge Article | Science & Tech. | 53.390371 | 95,631,842 |
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Metamorphosis is a biological process by which an animal physically develops after birth or hatching, involving a conspicuous and relatively abrupt change in the animal's body structure through cell growth and differentiation. Metamorphosis is iodothyronine-induced and an ancestral feature of all chordates. Some insects, fishes, amphibians, mollusks, crustaceans, cnidarians, echinoderms, and tunicates undergo metamorphosis, which is often accompanied by a change of nutrition source or behavior. Animals that go through metamorphosis are called metamorphoses. Animals can be divided into species that undergo complete metamorphosis ("holometaboly"), incomplete metamorphosis ("hemimetaboly"), or no metamorphosis ("ametaboly").
Scientific usage of the term is technically precise, and it is not applied to general aspects of cell growth, including rapid growth spurts. References to "metamorphosis" in mammals are imprecise and only colloquial, but historically idealist ideas of transformation and monadology, as in Goethe's Metamorphosis of Plants, have influenced the development of ideas of evolution.
In insects growth and metamorphosis are controlled by hormones synthesized by endocrine glands near the front of the body (anterior). Neurosecretory cells in an insect's brain secrete a hormone, the prothoracicotropic hormone (PTTH) that activates prothoracic glands, which secrete a second hormone, usually ecdysone (an ecdysteroid), that induces ecdysis. PTTH also stimulates the corpora allata, a retrocerebral organ, to produce juvenile hormone, which prevents the development of adult characteristics during ecdysis. In holometabolous insects, molts between larval instars have a high level of juvenile hormone, the moult to the pupal stage has a low level of juvenile hormone, and the final, or imaginal, molt has no juvenile hormone present at all. Experiments on firebugs have shown how juvenile hormone can affect the number of nymph instar stages in hemimetabolous insects.
All three categories of metamorphosis can be found in the diversity of insects, including no metamorphosis ("ametaboly"), incomplete or partial metamorphosis ("hemimetaboly"), and complete metamorphosis ("holometaboly"). While ametabolous insects show very little difference between larval and adult forms (also known as "direct development"), both hemimetabolous and holometabolous insects have significant morphological and behavioral differences between larval and adult forms, the most significant being the inclusion, in holometabolus organisms, of a pupal or resting stage between the larval and adult forms.
Development and terminology
In hemimetabolous insects, immature stages are called nymphs. Development proceeds in repeated stages of growth and ecdysis (moulting); these stages are called instars. The juvenile forms closely resemble adults, but are smaller and lack adult features such as wings and genitalia. The size and morphological differences between nymphs in different instars are small, often just differences in body proportions and the number of segments; in later instars, external wing buds form.
In holometabolous insects, immature stages are called larvae and differ markedly from adults. Insects which undergo holometabolism pass through a larval stage, then enter an inactive state called pupa (called a "chrysalis" in butterfly species), and finally emerge as adults.
The earliest insect forms showed direct development (ametabolism), and the evolution of metamorphosis in insects is thought to have fuelled their dramatic radiation (1,2). Some early ametabolous "true insects" are still present today, such as bristletails and silverfish. Hemimetabolous insects include cockroaches, grasshoppers, dragonflies, and true bugs. Phylogenetically, all insects in the Pterygota undergo a marked change in form, texture and physical appearance from immature stage to adult. These insects either have hemimetabolous development, and undergo an incomplete or partial metamorphosis, or holometabolous development, which undergo a complete metamorphosis, including a pupal or resting stage between the larval and adult forms.
A number of hypotheses have been proposed to explain the evolution of holometaboly from hemimetaboly, mostly centering on whether or not the intermediate hemimetabolous forms are homologous to pupal form of holometabolous forms.
More recently,[when?] scientific attention has turned to characterizing the mechanistic basis of metamorphosis in terms of its hormonal control, by characterizing spatial and temporal patterns of hormone expression relative to metamorphosis in a wide range of insects.
According to research from 2008, adult Manduca sexta is able to retain behavior learned as a caterpillar. Another caterpillar, the ornate moth caterpillar, is able to carry toxins that it acquires from its diet through metamorphosis and into adulthood, where the toxins still serve for protection against predators.
Many observations[when?] have indicated that programmed cell death plays a considerable role during physiological processes of multicellular organisms, particularly during embryogenesis and metamorphosis.
In typical amphibian development, eggs are laid in water and larvae are adapted to an aquatic lifestyle. Frogs, toads, and newts all hatch from the eggs as larvae with external gills but it will take some time for the amphibians to interact outside with pulmonary respiration. Afterwards, newt larvae start a predatory lifestyle, while tadpoles mostly scrape food off surfaces with their horny tooth ridges.
Metamorphosis in amphibians is regulated by thyroxin concentration in the blood, which stimulates metamorphosis, and prolactin, which counteracts its effect. Specific events are dependent on threshold values for different tissues. Because most embryonic development is outside the parental body, development is subject to many adaptations due to specific ecological circumstances. For this reason tadpoles can have horny ridges for teeth, whiskers, and fins. They also make use of the lateral line organ. After metamorphosis, these organs become redundant and will be resorbed by controlled cell death, called apoptosis. The amount of adaptation to specific ecological circumstances is remarkable, with many discoveries still being made.
Frogs and toads
With frogs and toads, the external gills of the newly hatched tadpole are covered with a gill sac after a few days, and lungs are quickly formed. Front legs are formed under the gill sac, and hindlegs are visible a few days later. Following that there is usually a longer stage during which the tadpole lives off a vegetarian diet. Tadpoles use a relatively long, spiral‐shaped gut to digest that diet.
Rapid changes in the body can then be observed as the lifestyle of the frog changes completely. The spiral‐shaped mouth with horny tooth ridges is resorbed together with the spiral gut. The animal develops a big jaw, and its gills disappear along with its gill sac. Eyes and legs grow quickly, a tongue is formed, and all this is accompanied by associated changes in the neural networks (development of stereoscopic vision, loss of the lateral line system, etc.) All this can happen in about a day, so it is truly a metamorphosis. It is not until a few days later that the tail is reabsorbed, due to the higher thyroxin concentrations required for tail resorption.
The Salamander development is highly diverse; some species go through a dramatic reorganization when transitioning from aquatic larvae to terrestrial adults, while others, such as the Axolotl, display paedomorphosis and never develop into terrestrial adults. Within the genus Ambystoma, species have evolved to be paedomorphic several times, and paedomorphosis and complete development which can both occur in some species.
In newts, there is no true metamorphosis because newt larvae already feed as predators and continue doing so as adults. Newts' gills are never covered by a gill sac and will be resorbed only just before the animal leaves the water. Just as in tadpoles, their lungs are functional early, but newts use them less frequently than tadpoles. Newts often have an aquatic phase in spring and summer, and a land phase in winter. For adaptation to a water phase, prolactin is the required hormone, and for adaptation to the land phase, thyroxin. External gills do not return in subsequent aquatic phases because these are completely absorbed upon leaving the water for the first time.
Basal caecilians such as Ichthyophis go through a metamorphosis in which aquatic larva transition into fossorial adults, which involves a loss of the lateral line. More recently diverged caecilians (the Teresomata) do not undergo an ontogenetic niche shift of this sort and are in general fossorial throughout their lives. Thus, most caecilians do not undergo an anuran-like metamorphosis.
Examples among the non-bony fish include the lamprey. Among the bony fish, mechanisms are varied.
Many species of flatfish begin their life bilaterally symmetrical, with an eye on either side of the body; but one eye moves to join the other side of the fish – which becomes the upper side – in the adult form.
The European eel has a number of metamorphoses, from the larval stage to the leptocephalus stage, then a quick metamorphosis to glass eel at the edge of the continental shelf (eight days for the Japanese eel), two months at the border of fresh and salt water where the glass eel undergoes a quick metamorphosis into elver, then a long stage of growth followed by a more gradual metamorphosis to the migrating phase. In the pre-adult freshwater stage, the eel also has phenotypic plasticity because fish-eating eels develop very wide mandibles, making the head look blunt. Leptocephali are common, occurring in all Elopomorpha (tarpon- and eel-like fish).
Most other bony fish undergo metamorphosis from embryo to larva (fry) and then to the juvenile stage during absorption of the yolk sac, because after that phase the individual needs to be able to feed for itself.
- Robert J. Denser Chordate Metamorphosis: Ancient Control by Iodothyronines Current Biology, 2008, Vol 18 No 13, R567-9. DOI: 10.1016/j.cub.2008.05.024
- "Metamorphosis, Henry George Liddell, Robert Scott, ''A, at Perseus". Perseus.tufts.edu. Retrieved 2012-08-26.
- "Online Etymology Dictionary". Etymonline.com. Retrieved 2012-08-26.
- Davies, 1998. Chapter 3.
- Gullan, P.J. & Cranston, P.S. 6.3 Process and Control of Moulting in The Insects: An Outline of Entomology. Blackwell Publishing, 2005. pp. 153-156.
- Slama; Williams (1965). "Juvenile hormone activity for the bug Pyrrhocoris apterus" (PDF). Proceedings of the National Academy of Sciences. 54 (2): 411–414. doi:10.1073/pnas.54.2.411. PMC .
- Singh, Amit; Konopova, Barbora; Smykal, Vlastimil; Jindra, Marek (2011). "Common and Distinct Roles of Juvenile Hormone Signaling Genes in Metamorphosis of Holometabolous and Hemimetabolous Insects". PLoS ONE. 6 (12): e28728. doi:10.1371/journal.pone.0028728. ISSN 1932-6203. PMC . PMID 22174880.
- Lowe, Tristan; Garwood, Russell P.; Simonsen, Thomas; Bradley, Robert S.; Withers, Philip J. (July 6, 2013). "Metamorphosis revealed: three dimensional imaging inside a living chrysalis". Metamorphosis revealed: three dimensional imaging inside a living chrysalis. 10 (84). 20130304. doi:10.1098/rsif.2013.0304. PMC . Retrieved June 11, 2015.
- Gullan, P.J. & Cranston, P.S. 6.2 Life History Patterns and Phases in The Insects: An Outline of Entomology. pp. 143–153. 2005 by Blackwell Publishing
- Douglas J. Blackiston, Elena Silva Casey & Martha R. Weiss (2008). "Retention of memory through metamorphosis: can a moth remember what it learned as a caterpillar?". PLoS ONE. 3 (3): e1736. doi:10.1371/journal.pone.0001736. PMC . PMID 18320055.
- Conner, W.E. (2009). Tiger Moths and Woolly Bears—behaviour, ecology, and evolution of the Arctiidae. New York: Oxford University Press. pp. 1–10.
- Laudet, Vincent (September 27, 2011). "The Origins and Evolution of Vertebrate Metamorphosis". Current Biology. 21: R726–R737. doi:10.1016/j.cub.2011.07.030.
- Dunker, Nicole; Wake, Marvalee H.; Olson, Wendy M. (January 2000). "Embryonic and Larval Development in the Caecilian Ichthyophis kohtaoensis (Amphibia, Gymnophiona): A Staging Table". Journal of Morphology. 243: 3–34. doi:10.1002/(sici)1097-4687(200001)243:1<3::aid-jmor2>3.3.co;2-4.
- San Mauro, D.; Gower, D. J.; Oommen, O. V.; Wilkinson, M.; Zardoya, R. (November 2004). "Phylogeny of caecilian amphibians (Gymnophiona) based on complete mitochondrial genomes and nuclear RAG1". Molecular Phylogenetics and Evolution. 33: 413–427. doi:10.1016/j.ympev.2004.05.014. PMID 15336675.
- Mader, Sylvia, Biology 9th ed. Ch. 31
- Peter B. Moyle and Joseph J. Cech Jr, Fishes: an introduction to ichthyology 5th ed. 9.3: "Development" pp 148ff
- Davies, R.G. (1998). Outlines of Entomology. Chapman and Hall. Second Edition. Chapter 3.
- Williamson D.I. (2003). The Origins of Larvae. Kluwer.
|Wikimedia Commons has media related to Biological life cycles.|
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The answer to what’s killing the world’s coral reefs may be found in a tiny chip that fits in the palm of your hand.
Scientists at Lawrence Berkeley National Laboratory and the University of California, Merced are using an innovative DNA array developed at Berkeley Lab to catalog the microbes that live among coral in the tropical waters off the coast of Puerto Rico. They found that as coral becomes diseased, the microbial population it supports grows much more diverse.
It’s unclear whether this surge in microbial diversity causes the disease, or is a result of it. What is clear is that coral disease is accompanied by a microbial bloom, and the DNA array, called the PhyloChip, offers a powerful way to both track this change and shed light on the pathogens that plague one of the ocean’s most important denizens.
“The PhyloChip can help us distinguish different coral diseases based on the microbial community present,” says Shinichi Sunagawa, a graduate student in UC Merced’s School of Natural Sciences who helped to conduct the research. “This is important because we need to learn more about what’s killing coral reefs, which support the most diverse ecosystem in the oceans. Losing them is much more than losing a reef, it means losing fish and marine mammals, even tourism.”
Worldwide, coral is threatened by rising sea temperatures associated with global warming, pollution from coastal soil runoff and sewage, and a number of diseases. The organism’s acute susceptibility to environmental change has given it a reputation as a canary in the coalmine: if it suffers, other species will soon follow.
Fortunately, there are ways to give coral a health checkup. Scientists have recently learned that healthy coral supports certain microbial populations, while coral inflicted with diseases such as White Plague Disease support different populations.
Understanding these microbial shifts could illuminate the magnitude and causes of coral disease, and possibly how to stop it, which is where the PhyloChip comes in. The credit card-sized chip can quickly detect the presence of up to 9,000 species of microbes in specially prepared samples of air, water, soil, blood, and tissue. The chip is carpeted with thousands of probes that scour a sample for the unique DNA signatures of most known species in the phyla bacteria and archaea. Specifically, the probes bind with a gene, called 16S rRNA, which is present in all life.
Developed by Gary Andersen, Todd DeSantis, Eoin Brodie, and Yvette Piceno of Berkeley Lab’s Earth Sciences Division, the PhyloChip offers a quick and low-cost way to canvas environmental samples for the presence of microorganisms.
“It’s a fast and inexpensive way to conduct a complete microbial community assessment of healthy and diseased corals,” says DeSantis.
In this study, the PhyloChip was used in conjunction with a more common technique, clone library sequencing, to analyze healthy and diseased samples of the coral Montastraea faveolata, which were plucked from reefs in the waters off Puerto Rico. The PhyloChip analyses, which were conducted at Berkeley Lab, found more species than the slower and more expensive clone sequencing technique.
But neither technique yielded what the scientists anticipated. The diseased coral was expected to contain the pathogen Aurantimonas corallicida because the coral exhibited symptoms identical to another coral species stricken by the pathogen. In this case, however, A. corallicida was not found.
“This means there are possibly other pathogens out there that we don’t know about,“ says Sunagawa. “There are only a handful of known coral pathogens, and we didn’t find the pathogen that causes a similar display in a different species of coral.“
In addition, the scientists have yet to determine whether the microbial bloom that accompanies coral disease causes the disease, or is caused by it.
“We need to determine what comes first: the disease or the microbial population change,” says DeSantis. “We don’t know if the disease-associated microbial population kills the coral, or if the microbes are simply feeding on dead coral tissue.”
Adds Sunagawa, “We have only recently realized how microbes, and microbial diversity, play an important role in the health of coral reefs. And the PhyloChip offers a great way to catalog the microbiota associated with coral reefs around the world.”
The study, “Bacterial diversity and White Plague Disease-associated community changes in the Caribbean coral Montastraea faveolata” is published in a recent issue of the International Society for Microbial Ecology Journal. In addition to DeSantis and Sunagawa, other scientists who contributed to the study include Michael DeSalvo, Monica Medina, and Christian Voolstra of UC Merced; Ernesto Weil of the University of Puerto Rico; and Gary Andersen, Eoin Brodie, and Yvette Piceno of Berkeley Lab.
Dan Krotz | EurekAlert!
Upcycling of PET Bottles: New Ideas for Resource Cycles in Germany
25.06.2018 | Fraunhofer-Institut für Betriebsfestigkeit und Systemzuverlässigkeit LBF
Dry landscapes can increase disease transmission
20.06.2018 | Forschungsverbund Berlin e.V.
A new manufacturing technique uses a process similar to newspaper printing to form smoother and more flexible metals for making ultrafast electronic devices.
The low-cost process, developed by Purdue University researchers, combines tools already used in industry for manufacturing metals on a large scale, but uses...
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
20.07.2018 | Power and Electrical Engineering
20.07.2018 | Information Technology
20.07.2018 | Materials Sciences | <urn:uuid:e8e62f01-7b32-4259-84ee-48add9b66537> | 4.0625 | 1,663 | Content Listing | Science & Tech. | 35.175249 | 95,631,847 |
Nonlinear and switchable metamaterials achieved by artificial structuring on the subwavelength scale have become a central topic in photonics research. Switching with only a few quanta of excitation per metamolecule, metamaterial’s elementary building block, is the ultimate goal, achieving which will open new opportunities for energy efficient signal handling and quantum information processing. Recently, arrays of Josephson junction devices have been proposed as a possible solution. However, they require extremely high levels of nanofabrication. Here we introduce a new quantum superconducting metamaterial which exploits the magnetic flux quantization for switching. It does not contain Josephson junctions, making it simple to fabricate and scale into large arrays. The metamaterial was manufactured from a high-temperature superconductor and characterized in the low intensity regime, providing the first observation of the quantum phenomenon of flux exclusion affecting the far-field electromagnetic properties of the metamaterial.
- Proceedings of the National Academy of Sciences of the United States of America
- Published over 1 year ago
We run a selection of algorithms on two state-of-the-art 5-qubit quantum computers that are based on different technology platforms. One is a publicly accessible superconducting transmon device (www.
- Proceedings. Biological sciences / The Royal Society
- Published almost 6 years ago
Vampire squid (Vampyroteuthis infernalis) are considered phylogenetic relics with cephalopod features of both octopods and squids. They lack feeding tentacles, but in addition to their eight arms, they have two retractile filaments, the exact functions of which have puzzled scientists for years. We present the results of investigations on the feeding ecology and behaviour of Vampyroteuthis, which include extensive in situ, deep-sea video recordings from MBARI’s remotely operated vehicles (ROVs), laboratory feeding experiments, diet studies and morphological examinations of the retractile filaments, the arm suckers and cirri. Vampire squid were found to feed on detrital matter of various sizes, from small particles to larger marine aggregates. Ingested items included the remains of gelatinous zooplankton, discarded larvacean houses, crustacean remains, diatoms and faecal pellets. Both ROV observations and laboratory experiments led to the conclusion that vampire squid use their retractile filaments for the capture of food, supporting the hypothesis that the filaments are homologous to cephalopod arms. Vampyroteuthis' feeding behaviour is unlike any other cephalopod, and reveals a unique adaptation that allows these animals to spend most of their life at depths where oxygen concentrations are very low, but where predators are few and typical cephalopod food is scarce.
Giant and colossal deep-sea squid (Architeuthis and Mesonychoteuthis) have the largest eyes in the animal kingdom [1, 2], but there is no explanation for why they would need eyes that are nearly three times the diameter of those of any other extant animal. Here we develop a theory for visual detection in pelagic habitats, which predicts that such giant eyes are unlikely to evolve for detecting mates or prey at long distance but are instead uniquely suited for detecting very large predators, such as sperm whales. We also provide photographic documentation of an eyeball of about 27 cm with a 9 cm pupil in a giant squid, and we predict that, below 600 m depth, it would allow detection of sperm whales at distances exceeding 120 m. With this long range of vision, giant squid get an early warning of approaching sperm whales. Because the sonar range of sperm whales exceeds 120 m [3-5], we hypothesize that a well-prepared and powerful evasive response to hunting sperm whales may have driven the evolution of huge dimensions in both eyes and bodies of giant and colossal squid. Our theory also provides insights into the vision of Mesozoic ichthyosaurs with unusually large eyes.
The Josephson effect is perhaps the prototypical manifestation of macroscopic phase coherence, and forms the basis of a widely used electronic interferometer–the superconducting quantum interference device (SQUID). In 1965, Maki and Griffin predicted that the thermal current through a temperature-biased Josephson tunnel junction coupling two superconductors should be a stationary periodic function of the quantum phase difference between the superconductors: a temperature-biased SQUID should therefore allow heat currents to interfere, resulting in a thermal version of the electric Josephson interferometer. This phase-dependent mechanism of thermal transport has been the subject of much discussion but, surprisingly, has yet to be realized experimentally. Here we investigate heat exchange between two normal metal electrodes kept at different temperatures and tunnel-coupled to each other through a thermal ‘modulator’ (ref. 5) in the form of a direct-current SQUID. We find that heat transport in the system is phase dependent, in agreement with the original prediction. Our Josephson heat interferometer yields magnetic-flux-dependent temperature oscillations of up to 21 millikelvin in amplitude, and provides a flux-to-temperature transfer coefficient exceeding 60 millikelvin per flux quantum at 235 millikelvin. In addition to confirming the existence of a phase-dependent thermal current unique to Josephson junctions, our results point the way towards the phase-coherent manipulation of heat in solid-state nanocircuits.
Abstract Sourcing energy for reproduction is a major driver of the life-history characteristics of animals. Unlike other molluscs, cephalopods do not appear to have significant glycogen stores, and energy is either sourced directly from ingested food or mobilized from protein stores in the muscle. Given the importance of protein to cephalopods, this study quantified changes in protein turnover in the muscle tissue in reproductively immature and maturing/mature individuals. Quantifying protein accretion and protein synthesis allowed an assessment of protein turnover in immature and maturing individuals of the southern dumpling squid (Euprymna tasmanica), which has fast nonasymptotic growth, has a short generation time, and does not use lipid stores. This study found that protein turnover slowed in the mantle muscle tissue with gonad growth, suggesting an adaptive response to the energy demands associated with reproduction but one that allows for continued somatic growth and muscle function in these animals. However, the cost of reproduction may be indirect, with less energy available for somatic repair, and therefore may be responsible for the rapid senescence typical of many cephalopod species.
In a conventional Josephson junction of graphene, the supercurrent is not turned off even at the charge neutrality point, impeding further development of superconducting quantum information devices based on graphene. Here we fabricate bipolar Josephson junctions of graphene, in which a p-n potential barrier is formed in graphene with two closely spaced superconducting contacts, and realize supercurrent ON/OFF states using electrostatic gating only. The bipolar Josephson junctions of graphene also show fully gate-driven macroscopic quantum tunnelling behaviour of Josephson phase particles in a potential well, where the confinement energy is gate tuneable. We suggest that the supercurrent OFF state is mainly caused by a supercurrent dephasing mechanism due to a random pseudomagnetic field generated by ripples in graphene, in sharp contrast to other nanohybrid Josephson junctions. Our study may pave the way for the development of new gate-tuneable superconducting quantum information devices.
Non-Abelian anyons-particles whose exchange noncommutatively transforms a system’s quantum state-are widely sought for the exotic fundamental physics they harbour and for quantum computing applications. Numerous blueprints now exist for stabilizing the simplest type of non-Abelian anyon, defects binding Majorana modes, by interfacing widely available materials. Here we introduce a device fabricated from conventional fractional quantum Hall states and s-wave superconductors that supports exotic non-Abelian defects binding parafermionic zero modes, which generalize Majorana bound states. We show that these new modes can be experimentally identified (and distinguished from Majoranas) using Josephson measurements. We also provide a practical recipe for braiding parafermionic zero modes and show that they give rise to non-Abelian statistics. Interestingly, braiding in our setup produces a richer set of topologically protected operations when compared with the Majorana case. As a byproduct, we establish a new, experimentally realistic Majorana platform in weakly spin-orbit-coupled materials such as gallium arsenide.
Superconducting and topological states are two most intriguing quantum phenomena in solid materials. The entanglement of these two states, the topological superconducting state, will give rise to even more exotic quantum phenomena. While many materials are found to be either a superconductor or a topological insulator, it is very rare that both states exist in one material. Here, we demonstrate by first-principles theory as well as scanning tunnelling spectroscopy and angle-resolved photoemission spectroscopy experiments that the recently discovered ‘two-dimensional (2D) superconductor’ of single-layer FeSe also exhibits 1D topological edge states within an energy gap of ∼40 meV at the M point below the Fermi level. It is the first 2D material that supports both superconducting and topological states, offering an exciting opportunity to study 2D topological superconductors through the proximity effect.
Superconducting circuits offer tremendous design flexibility in the quantum regime culminating most recently in the demonstration of few qubit systems supposedly approaching the threshold for fault-tolerant quantum information processing. Competition in the solid-state comes from semiconductor qubits, where nature has bestowed some very useful properties which can be utilized for spin qubit-based quantum computing. Here we begin to explore how selective design principles deduced from spin-based systems could be used to advance superconducting qubit science. We take an initial step along this path proposing an encoded qubit approach realizable with state-of-the-art tunable Josephson junction qubits. Our results show that this design philosophy holds promise, enables microwave-free control, and offers a pathway to future qubit designs with new capabilities such as with higher fidelity or, perhaps, operation at higher temperature. The approach is also especially suited to qubits on the basis of variable super-semi junctions. | <urn:uuid:2685e28b-9d84-4b9a-a6ba-c79f0dfb3744> | 2.734375 | 2,200 | Content Listing | Science & Tech. | 7.486582 | 95,631,867 |
Microgomphus nyassicus (Grünberg, 1902)
- scientific: M. mozambicensis Pinhey, 1959
Type locality: Mozambique-Zimbabwe border, Zimbabwe
Separation from the possibly synonymous Microgomphus schoutedeni is tentative: may range from southern Kenya to Katanga and north-eastern South Africa, having the inner branch about as thick and long as the outer branch, with a wider cleft of the epiproct. [Adapted from Dijkstra & Clausnitzer 2014]
Streams shaded by forest, but possibly also in open areas. Probably often with coarse detritus. Inferred to occur from 100 to 1800 m above sea level.
Appendages (dorsal view)
Appendages (lateral view)
Appendages (ventral view)
Map citation: Clausnitzer, V., K.-D.B. Dijkstra, R. Koch, J.-P. Boudot, W.R.T. Darwall, J. Kipping, B. Samraoui, M.J. Samways, J.P. Simaika & F. Suhling, 2012. Focus on African Freshwaters: hotspots of dragonfly diversity and conservation concern. Frontiers in Ecology and the Environment 10: 129-134.
- Grünberg, K. (1902). Sitzungsberichte Gesellschaft naturforschender Freunde Berli, 9, 230-237.
- Pinhey, E.C.G. (1961). Dragonflies (Odonata) of Central Africa. Occasional Papers Rhodes-Livingstone Museum, 14, 1-97. [PDF file]
- Pinhey, E.C.G. (1966). Check-list of dragonflies (Odonata) from Malawi, with description of a new Teinobasis Kirby. Arnoldia, 2, 1-24. [PDF file]
Citation: Dijkstra, K.-D.B (editor). African Dragonflies and Damselflies Online. http://addo.adu.org.za/ [2018-07-17]. | <urn:uuid:85c46146-b3d0-472e-a04f-0f6ac6a9de81> | 3.046875 | 469 | Knowledge Article | Science & Tech. | 65.117427 | 95,631,886 |
A Chiral Molecule is a type of molecule that is non-superposable over its mirror image. On the other hand, achiral molecules are one that are superposable over its mirror image, as in they are identical to their mirror images. Thus, it can be seen that chirality usually stems from some sort of asymmetry in the carbon-based molecule. Consider the following molecule:
Figure 1: (H, R, COOH, NH2)
The above amino acid is chiral as if you create its mirror image, it can be seen that these are not identical. Thus, in order to separate non-superposable mirror images, there is an important system to help categorize and identify different chiral molecules. The R- and S- configurations were devised to help categorize molecules based on the priority of the substituents bonded to the center atom. So the first step involves orienting the molecule so that the substituent with the least priority (generally, lowest in atomic/molecular weight) is pointing away from the viewer. Then looking at the remaining three substituents: if the priority decreases in a clockwise fashion, then the molecule will be labeled R; if the priority decreases in a counter-clockwise fashion, then the molecule will be labeled S.
Thus, understanding chirality is extremely important as the concept is heavily involved in a multitude of organic reactions.© BrainMass Inc. brainmass.com July 16, 2018, 9:35 pm ad1c9bdddf | <urn:uuid:6551b9af-ac23-4f67-bbae-5572bf103518> | 3.65625 | 319 | Knowledge Article | Science & Tech. | 30.236883 | 95,631,887 |
The effects of climate change, overfishing, chronic oil pollution and predation by introduced mammals are among the major factors cited repeatedly by penguin scientists as contributing to these population drops. Prior to the conference, thirteen of these penguin species were already classified as endangered or threatened. Some penguin species may face extinction in this century.
More than 180 penguin biologists, government officials, conservation advocates, and zoo and aquarium professionals from 22 nations have convened in Boston for the five day International Penguin Conference, which is being hosted this year by the New England Aquarium. The conference is held every three to four years, and this is the first time that it has been held in the Northern Hemisphere.
Penguins are found exclusively in the Southern Hemisphere with a single species on the Galapagos Islands at the Equator to four Antarctic penguin species that are most well known to the public, yet 13 other species also live in South America, southern Africa, Australia, New Zealand, and on the many sub-Antarctic islands. Throughout their ranges, nearly all of penguin species are in significant decline or under duress due to a host of common factors.
Earlier this year, African penguins, found in Namibia and South Africa, were reclassified internationally as endangered as many breeding colonies in the western part of their range have disappeared. Important food bearing cold water currents have shifted and are now routinely found much further offshore. The increased roundtrip commuting distance for African penguins to obtain food has been devastating to their population.
Scientists are closely watching the potential effects on several Antarctic penguin species that are highly dependent on the presence of sea ice for breeding, foraging and molting. Emperor penguins, which were the subject of “March of the Penguins,” could see major population declines by 2100, if they do not adapt, migrate and change the timing of their growth stages.
Adelie penguin colonies in the Antarctic’s Ross Sea have coped for several years with two super-sized icebergs that have grounded there and created an enormous physical barrier. It has resulted in lower breeding rates and the migration of many animals out of the area.
Sea ice also creates an important nursey cover for juvenile krill which feed on ice algae. Krill is the primary fuel at the base the Antarctic food chain. Reduced sea ice cover has led to a dramtic decline in krill and will likely lead to a decline in many wildlife populations further up the food chain that relies on krill as its foundation food source.
The effects of climate change on penguins are very real. Many environmental conditions are changing and much less predictable. For penguins living in harsh conditions, the ability to properly time when to migrate, nest, mate and seek food are critical decisions often with a very small margin for error, both for both individual animals and entire species.OVERFISHING AND BYCATCH
Thousands of penguins are also killed annually when caught in fixed fishing nets.CHRONIC OILING
SUMMARY: The goal of the 7th International Penguin Conference is to present ongoing research, identify current and emerging conservations issues and create action plans that will help create a strategic global effort on behalf of these threatened species.
FOR MORE INFORMATION, please go to: http://penguinconference.org/
Tony LaCasse | Newswise Science News
Barium ruthenate: A high-yield, easy-to-handle perovskite catalyst for the oxidation of sulfides
16.07.2018 | Tokyo Institute of Technology
The secret sulfate code that lets the bad Tau in
16.07.2018 | American Society for Biochemistry and Molecular Biology
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
16.07.2018 | Physics and Astronomy
16.07.2018 | Life Sciences
16.07.2018 | Earth Sciences | <urn:uuid:9ae78b36-3a49-49ad-90c1-b421a48796b3> | 3.984375 | 1,336 | Content Listing | Science & Tech. | 37.149991 | 95,631,895 |
NASA's Terra satellite passed over Tropical Storm Hanna on Oct. 27 when it made landfall near the northern Nicaragua and southern Honduras border.
On Oct. 27 at 16:00 UTC (12 p.m. EDT) the MODIS instrument aboard NASA's Terra satellite captured a visible image of Tropical Storm Hanna straddling the border between Honduras and Nicaragua.
The image, created by NASA's MODIS Rapid Response Team at NASA's Goddard Space Flight Center in Greenbelt, Maryland, showed strong thunderstorms on both sides of the border, bringing heavy rainfall to those area.
At 10 a.m. EDT on Oct. 28, Roatan Airport in Guanaja, Honduras reported heavy rainfall with thunderstorms. At the same time, Islas Del Cisne, Honduras reported thunderstorms.
On Oct. 28, the National Hurricane Center noted that Hanna's remnants continued to generate heavy rainfall and isolated thunderstorms over Honduras and northern Nicaragua as well as the Yucatan basin south of 20 north latitude and west of 80 west longitude.
The government of Honduras has discontinued the tropical storm warning for the coast of Honduras. There are no coastal watches or warnings in effect. The National Hurricane Center expects the remnants to dissipate by Oct. 28 at 8 p.m. EDT.
NASA's Goddard Space Flight Center
Rob Gutro | EurekAlert!
New research calculates capacity of North American forests to sequester carbon
16.07.2018 | University of California - Santa Cruz
Scientists discover Earth's youngest banded iron formation in western China
12.07.2018 | University of Alberta
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
17.07.2018 | Information Technology
17.07.2018 | Materials Sciences
17.07.2018 | Power and Electrical Engineering | <urn:uuid:1198c014-3f89-4a48-96d6-383072773dc9> | 3.171875 | 903 | Content Listing | Science & Tech. | 43.108546 | 95,631,913 |
POLinSAR: Advances in radar remote sensing
An advanced technique for analysing radar images shows tremendous promise for scientists studying forests, agriculture, ice and other terrain types, but experts at a recent ESA workshop cautioned that research work is needed before practical applications can be developed.
More than 120 scientists and researchers from 20 countries gathered recently at ESA’s ESRIN facility in Frascati, Italy, for a three-day workshop to share the latest results on scientific tests and potential applications of SAR polarimetry and polarimetric interferometry.
With ten radar satellites expected to be in orbit by the end of the decade, radar imagery and POLinSAR techniques could find practical uses ranging from detecting buried landmines, providing early warnings of threats to agricultural areas, and certifying forests for logging to monitoring compliance with international treaties on global warming and helping national governments to protect the biodiversity and ecological balance of their forests, wetlands and other natural assets.
"We are just at the starting point of revealing new applications," commented Yves-Louis Desnos, workshop chairman and ESA’s Head of R&D Support for the Exploitation and Science Division of the Earth Observation Programme.
From polarimetry to polarimetric interferometry
The workshop addressed the latest research developments that are moving from classical SAR studies to polarimetric SAR (or SAR polarimetry, as it’s also called). This features the capability to sense the Earth through various polarisation combinations. "SAR polarimetry clearly has many potential applications in agriculture monitoring, oil slicks, forest and sea ice classification," comments Henning Skriver, associate professor with the Technical University of Denmark (DTU). "It also needs further scientific development."
Known by the unwieldy acronym, POLinSAR, the technique combines varying the orientation, or polarisation, of radar signals (POLarimetry) with the analysis of the phase differences in the signal to produce differential range and range-change measurements (interferometry) from two or more images captured by synthetic aperture radars (SARs). Taken together, polarimetry and interferometry offers the potential to see the Earth in three dimensions.
POLinSAR analysis techniques emerged in the mid-1990s and are developing quickly. "POLinSAR has matured from a ‘first-results’ to a science status," said Konstantinos Papathanassiou, a researcher with the Institute for Radio Frequency Technology and Radar Systems at German Aerospace Centre (DLR). "You can do things that were not possible before and are needed now."
Seeing the forest, measuring the trees<(b>
The capability of radar to penetrate ground cover and see the underlying terrain, coupled with POLinSAR techniques to detect forest canopies, make classifying trees and how tall they are using SAR imagery a possibility. This may sound of interest only to a narrow band of scientists, until one realizes that determining the types and heights of trees in a forest are critical ingredients in determining its biomass – a quantitative estimate of the entire amount of organic material in a particular habitat.
In turn, a forest’s biomass, together with how it changes over time, are key elements in determining an area’s capacity to act as a carbon sink, soaking up carbon-based gases and cleansing the atmosphere of major types of pollution blamed for the greenhouse effect and global warming. Producing accurate forest biomass estimates, and how they are changing over time, are a critical challenge to environmental scientists to whom national governments are turning for help in meeting their international obligations to stabilise greenhouse-gas emissions under the Kyoto Protocol.
As a result, a number of tests are underway to assess how SAR imagery could be used to produce accurate biomass estimates. Shane Cloude, with the UK-based AEL Consultants, presented the results of an ESA-funded project that employed polarimetric interferometry to measure the height of trees with data captured by an airplane-mounted SAR. A forest of Scotch pine trees, naturally enough in Scotland, was chosen to serve as a testing area.
The results of the test were promising, within about a ten percent margin of error. Cloude reported that evaluation "consistently underestimated" the height of the trees by about a half-metre when the SAR data were matched against so-called ground truth – actual on-site measurements.
"It’s tough to do, and we are further along with single-species forests," Cloude said. "Forest biomass estimates are very important for measuring compliance with Kyoto targets, but we are far away from the political dimensions of using POLinSAR techniques for monitoring compliance."
New model for classifying agriculture
At a roundtable discussion on the forest-related study results presented at the conference, several participants urged that research be expanded to include more types of forests. Dirk Hoekman, with the Department of Environmental Sciences at Wageningen University in the Netherlands, pointing out that the recent Indonesian forest fires released a gigaton of carbon into the atmosphere, or one-third of the total annual increase of global carbon gases. More attention from POLinSAR researchers should be paid to tropical and peat moss forests, he said.
Hoekmans own paper on a new model for classifying the types of agriculture in SAR images captured the attention of some of the scientists at the meeting because of the promise of improved accuracy of the results. Accurately classifying agricultural types and other terrain features such as land cover and sea ice in SAR imagery is a problem that has plagued researchers and hampered the development of reliable applications. Tests of crop classifications from imagery taken over the Dutch Flevoland agricultural test site indicate that new ways to classify the radar data with levels of accuracy of 90.4% for C-band and 88.7 % for L-band, according to Hoekman’s paper presented to the conference.
"The new classification method probably will solve one of the problems we have had with existing methods," said DTU’s Skriver. "These methods have not been able to fully cope with the natural variation within individual classes and, hence, have limited the classification accuracy."
Sessions reveal potential applications
Workshop presentations, including lively poster session during which researchers were limited to two minutes to present a synopsis of their work and extend an invitation to speak at greater length, gave a glimpse at the diversity of research now underway in the SAR science community. Among the highlights:
An evaluation the best SAR polarisation methods to use for detecting land mines, including modern plastic versions that are nearly invisible to conventional ground-penetrating radars. Juan Lopez-Sanchez from Spain’s University of Alicante explained how a test conducted at a European microwave lab found that circular or near-circular SAR polarisations were best to distinguish buried mines from the surrounding soil. A complete analysis of the test results is currently underway, he added.
Polarimetric SAR techniques could improve the detection and classification of oil slicks. Polarization coherence and the polarimetric anisotropy have been suggested as ways to classify terrain surface roughness, stated Joaquim Fortuny-Guasch with Italy’s Joint Research Centre. After an examination of imagery of areas of the North Sea, the English Channel, northern Germany, and Pantelleria Island in southern Italy, preliminary results indicated that surface roughness is highly correlated with changes in the thickness and/or the texture of the oil layer.
Hugh Corr with the British Antarctic Survey presented details of how ground-based SARs and polarimetric techniques have been used to look through ice more than 2.5 km thick to study crystal formations and distinguish subsurface ice flows.
Interferometric studies using SAR data under an ESA-sponsored project is revealing how the land around Polish coal mines is subsiding at a rate up to a half-metre per month, according to Zbigniew Perski, scientist with Poland’s University of Silesia. "Today, the determination of the areas affected by terrain deformation risks becomes on of the most promising applications for operational use of SAR data," he stated.
Plans for new space SARs
With their all-weather and nighttime capabilities, coupled with these promising new analytical methods for interpreting the results, space-based radars are providing new insights into the Earth’s land, waters and atmosphere. Participants at the POLinSAR workshop heard details of upcoming satellite missions that will incorporate new advances in SAR technology, faster revisit times, and a more complete inventory of those spots on Earth of interest to the scientists and the public.
Gordon Staples with Radarsat International detailed current planning for the Radarsat-2 follow-on to the existing orbiting Canadian Radarsat spacecraft. Planned for a 2004 launch, the spacecraft is being funded through a cooperative arrangement between the Canadian government and Radarsat Internationals parent company, MacDonald Dettwiler. It will feature a high-resolution, 3-metre resolution mode and the capability to scan both right and left along the satellite’s track by physically rotating the spacecraft one a day. After an evaluation of 32 application areas for radar imagery, Staples said that the new satellite offers the best improvements in examining crop types, crop conditions and providing information about sea ice.
The TerraSAR-X satellite will be the first German SAR for scientific and commercial applications, said DLRs Alberto Moreira. Planned for a 2005 launch, the X-band SAR features a 1-metre “spotlight” mode, with an experimental 0.6-metre resolution using the spacecraft’s 300-MHz-bandwidth transmit capability, Moreira said. Another unique feature of the spacecraft is the capability to split the antenna receiving the return radar signal into two separate channels to allow for the tracking of moving targets for measuring water currents and monitoring traffic over a large area.
"The X-band applications include mostly sea ice, snow cover and urban planning," Moreira said, with other uses including agricultural, map-making and risk assessment studies for floods, fires and storms.
A four-satellite constellation of X-band SARs is planned as the Cosmo-SkyMed program, developed by the Italian Space Agency with the cooperation of France’s space agency, CNES. The dual, military/civilian mission follows Italy’s HELIOS 1 military observation satellite that is ending in 2004. With the first launch planned in 2005, Cosmo-SkyMed will be coordinated with optical satellites, feature revisit times of a few hours and metre and sub-metre resolutions.
ESA’s Envisat Mission Manager Henri Laur provided workshop participants with a status report on ESA’s latest Earth observation mission. He stressed the synergy among the 10 sensors carried by the Envisat satellite, point out that Envisat’s advanced SAR that can switch between horizontal and vertical polarisations of the radar signal can acquire imagery simultaneously with the MERIS imaging spectrometer to allow a more complete top and bottom analysis of various natural phenomena such as hurricanes.
Responding to questions concerning the availability of Envisat imagery, Laur said that all Envisat instruments are completely activated and operating, all ASAR products activated to be released, and data are being delivered to scientific users.
A new Envisat ground station, located in Svalbard at the northern edge of Norway, brings additional capability to the network for delivering Envisat data to users, the ESA official added. The arrival on-station of Artemis, ESA’s inter-satellite data relay spacecraft, will allow data to be received directly at ESA’s ESRIN facility, Laur said, with tests of the system to be conducted in February and March.
POLinSAR: stay tuned for more to come
The ESA POLinSAR workshop clearly demonstrated the strides taken by the radar research community in the past few years in radar polarimetry techniques and applications, and that more work is needed to move from the lab to practical uses.
"The workshop showed that the performance of several remote-sensing applications increases by introducing polarimetric information," commented DLR’s Papathanassiou. "The discussions also highlighted the limitations and problems in establishing applications."
Yves-Louis Desnos | alfa
The most recent press releases about innovation >>>
Die letzten 5 Focus-News des innovations-reports im Überblick:
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the... | <urn:uuid:c2f00f1d-de06-42a3-be93-c32a15817dd7> | 3.34375 | 3,095 | Content Listing | Science & Tech. | 19.622026 | 95,631,914 |
Axiomatic probability is a unifying probability theory. It sets down a set of axioms (rules) that apply to all of types of probability, including frequentist probability and classical probability. These rules, based on Kolmogorov’s Three Axioms, set starting points for mathematical probability.
Kolmogorov’s Three Axioms
The three axioms are:
- For any event A, P(A) ≥ 0. In English, that’s “For any event A, the probability of A is greater or equal to 0”.
- When S is the sample space of an experiment; i.e., the set of all possible outcomes, P(S) = 1. In English, that’s “The probability of any of the outcomes happening is one hundred percent”, or—paraphrasing— “anytime this experiment is performed, something happens”.
If A and B are mutually exclusive outcomes, P(A ∪ B ) = P(A) + P(B).
Here ∪ stands for ‘union’. We can read this by saying “If A and B are mutually exclusive outcomes, the probability of either A or B happening is the probability of A happening plus the probability of B happening”
Many important laws are derived from Kolmogorov’s three axioms. For example, the Law of Large Numbers can be deduced from the laws by logical reasoning (Tijms, 2004).
Just because these axioms are universal, doesn’t mean they provide all the answers. For example, any function that satisfies all three axioms is called a probability function. However, the axioms don’t tell you which function to choose; it merely states that the probability function you choose must satisfy the rules.
Fine (2014) goes so far as to say the axioms lack “essential content”. What these three axioms don’t do:
- Tell us where and when to apply the rules,
- Give us guidelines or procedures for calculating probabilities,
- Any insights to the nature of random processes.
The Development of Axiomatic Probability
The oldest type of probability is classical probability; it is usually applied to easy-to-analyze situations like gambling games.Let’s say a random experiment (such as the throw of a dice) results in a finite number, n, of equally likely outcomes. If m of those outcomes have a certain attribute, the probability of that attribute would be the fraction m/n. This is useful for analyzing dice throws and card picks, but is less applicable to more complicated situations of daily life.
Frequentist probability was, historically, the next type of probability to be developed. Frequentist statistics uses rigid frameworks, the type of frameworks that you learn in basic statistics, like p-values and confidence intervals.
- For every stats problem, there’s data.
- There’s a test for each set of data.
- Every test has its own rigid rules.
Tests are based on the fact that every experiment can be repeated infinitely. Deviation from this set of rules is never allowed, and if you dare to deviate, your methods will be chided as statistically unsound.
Frequentist probability has more applicability than the classical model, but is still very limited.
- Fine, T. (2014). Theories of Probability: An Examination of Foundations. Academic Press.
- Morey, Edward. 3 Basic Definitions of Probability Theory
Retrieved from https://www.colorado.edu/economics/morey/6818/3defprob.pdf on April 15, 2018
- Myers, Daniel. CS 547 Lecture 6: Axioms of Probability
Retrieved from http://pages.cs.wisc.edu/~dsmyers/cs547/lecture_6_probability.pdf on April 15, 2018
- Tijms, H. (2004). Understanding Probability: Chance Rules in Everyday Life. Cambridge University Press.
- Universitat Zurich, Axiomatic Probability
Retrieved from https://www.math.uzh.ch/index.php?file&key1=45741 on April 15, 2018
If you prefer an online interactive environment to learn R and statistics, this free R Tutorial by Datacamp is a great way to get started. If you're are somewhat comfortable with R and are interested in going deeper into Statistics, try this Statistics with R track.Comments? Need to post a correction? Please post on our Facebook page. | <urn:uuid:626cbfd4-2601-4c8e-9078-40db7369427a> | 3.921875 | 990 | Tutorial | Science & Tech. | 47.529009 | 95,631,982 |
In this course, we will be looking at general solutions of tangent , where k is a real number
There is always a value between and such that tangent (k has to be a real number). This value is known as the principal value of . is known as the principal solution of . The intersection of the line and the tangent graph shows that are also solutions of tangent .
The general expression of these solutions is given by = , Z
This is called the general solution of tangent
If the solution is required in degrees, then the general solution is , Z
Scholar's Tip: If , the general solution would be , Z
Find the general solution to the following tangent equations.
a) tangent b) tangent
a) This is similar to solving for the general solution of other trigonometry functions. We have to convert into its tangent form.
b) Let's try it out when degrees are involved.
You may want to look at sine, cosine solutions as well . There is also the law of sines and law of cosines .
Return to Trigonometry Help or Basic Trigonometry . | <urn:uuid:e5768e51-4123-425a-9262-02ec1a6e38c8> | 3.6875 | 239 | Tutorial | Science & Tech. | 57.098506 | 95,631,991 |
A team with researchers from Freiburg discovered a new mechanism for the regulation of protein synthesis
Mitochondria, best known for their role as cellular power plants, perform numerous vital tasks in the cell. During cell respiration, reactive oxygen species can be formed in mitochondria. If these are present in excess, their high reactivity leads to irreparable damage to important cellular components.
This so-called oxidative stress is assumed to play a causal role in many diseases and in ageing processes. In low concentrations, however, reactive oxygen species can also act as important second messengers in the cell. Here, specific, so-called redox-active thiols in distinct proteins are modified. This type of oxidative modification is reversible and, like a nano-switch, can regulate the function of a protein.
A German-Polish research team led by Prof. Dr. Bettina Warscheid from the University of Freiburg and Prof. Dr. Agnieszka Chacinska from the Centre of New Technologies in Warsaw/Poland has discovered a new mechanism that enables mitochondria with impaired redox balance to regulate the synthesis of new proteins in the cytoplasm. The mitochondria use reactive oxygen species as signal to slow down the cellular protein synthesis machinery. The study was published in the current issue of the scientific journal "Nature Communications".
Using quantitative mass spectrometry, Dr. Ida Suppanz from Warscheid's research group first determined the redox state of thiols in thousands of proteins of the baker's yeast Saccharomyces cerevisiae. She discovered so far unknown redox-active thiols in components of the ribosomes at which new proteins are synthesized.
Dr. Ulrike Topf from Chacinska’s group observed that increased levels of reactive oxygen species inhibit protein synthesis. Using biochemical and cell biological methods, she showed that damaged mitochondria can signal their metabolic state to the protein synthesis machinery via reactive oxygen species and, thereby, slow down cellular protein synthesis.
It is assumed that the temporary reduction of the protein synthesis rate under oxidative stress has a positive effect on the survival of the cells as it is believed to help to restore cellular homeostasis. This also prevents the cell from synthesizing proteins that cannot be taken up by damaged mitochondria, which, as a consequence, accumulate in the cytoplasm and thus need to be degraded. Researches of Warscheid’s and Chacinska’s teams explained how the cell reacts to such a protein accumulation in 2015 in the journal "Nature" (press release: www.pr.uni-freiburg.de/pm-en/2015/pm.2015-08-13.119-en).
Furthermore, the researchers were able to show that this newly discovered regulatory mechanism does not only exist in yeast, but also in human cells. Knowledge on how dysfunctional mitochondria communicate with other cellular components can help to elucidate the mechanisms of age-related and neurodegenerative diseases in the future.
Bettina Warscheid is head of the department of Biochemistry - Functional Proteomics, Institute of Biology II, and member of the Excellence Cluster BIOSS Centre for Biological Signalling Studies at the University of Freiburg. Ida Suppanz is a postdoctoral fellow in the group of Bettina Warscheid.
Ulrike Topf*, Ida Suppanz*, Lukasz Samluk, Lidia Wrobel, Alexander Böser, Paulina Sakowska, Bettina Knapp, Martyna K. Pietrzyk, Agnieszka Chacinska# & Bettina Warscheid#. Quantitative proteomics identifies redox switches for global translation modulation by mitochondrially produced reactive oxygen species (2018). Nature Communications. DOI: 10.1038/s41467-017-02694-8. (*#These authors contributed equally.)
Prof. Dr. Bettina Warscheid
Institut für Biologie II
Rudolf-Werner Dreier | idw - Informationsdienst Wissenschaft
NYSCF researchers develop novel bioengineering technique for personalized bone grafts
18.07.2018 | New York Stem Cell Foundation
Pollen taxi for bacteria
18.07.2018 | Technische Universität München
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
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EXPERIMENT NO. 4
Claver, L. Z. X. Y.1, Palad, C. C.2, Rocha, R. D. P3
1Anthropology Department, College of Social Sciences and Philosophy, 2National Institute of Geological Sciences, College of Science, 3Department of Food Science and Nutrition, College of Home Economics,
University of the Philippines, Diliman, Quezon City 1101 Philippines -------------------------------------------------
Keywords: forward and reverse reactions, equilibrium constant, Le Chatelier’s Principle, reaction quotient
In chemical kinetics, it is stated that a forward reaction’s rate is dependent on the given concentration of the reactants. In other words, the relationship of the rate of a reaction is directly proportional to the concentration. While the reaction is taking place, the concentration of the reactants are decreased, as these reactants are formed into products. During the decrease of the reactants’ concentration, the rate of the forward reaction also decreases. As more and more products are being formed, they start to reform to their constituent reactants again. This causes the reverse reaction rate to increase this time. This process continues to happen until the rate of the forward reaction and the backward reaction becomes equal. When this happens, chemical equilibrium is achieved by the reaction system.
Whenever equilibrium is achieved, at any given time, both reactants and products will be present at any given point in time since their concentrations remain constant. Given a reaction,
aA + bB ⇌ cC + dD
kf[A]a[B]b = kr[C]c[D]d
kfkr = Keq = [C]c[D]d (1)
A factor in determining whether to which direction a reaction will go to that has not yet reached equilibrium, is the reaction quotient Q. Q is just the same as the Keq expression, but the main difference is that the concentrations of the reactants and the products used in the equation are still not yet at equilibrium. Whenever Q<Keq, the reaction will favor the forward reaction, but when Q>Keq, the reaction will favor the reverse reaction.
Go or Gibb’s Free Energy that indicates a spontaneity of a reaction, and Keq are related through the general thermodynamic equation where both gaseous and solution forms appear in the chemical equation:
Go = -RTlnK (2)
Whenever K is greater than 1, the forward reaction is spontaneous, meaning, the amount of products is greater than the amount of reactants at equilibrium. For this, Go<0. On the other hand, whenever Keq is less than 1, the reverse reaction is spontaneous, and the amount of reactants is great than the products at equilibrium. For this, Go>0.
While the relationship of Go and Keq tells us about the spontaneity of a system and to which direction it will go to, Le Chatelier’s Principle tells us what would happen to a system at equilibrium whenever a stress is applied onto it. The kinds of stresses that could be applied are: change in temperature, change in volume or pressure (applicable in gases only), and change in concentration of either the reactants or products.
As said above, one of the stresses that could be applied to a system is changing the concentration of the reactants or the products. From the equilibrium expression, whenever concentration of the product is increased, it will favor the reverse reaction. The converse holds when the concentrations of the reactants are increased.
These two stresses are done in this experiment, and will be used to observe whether to which direction the reaction will shift to reestablish its equilibrium. Several equilibrium systems are used, such as the Iron (II)-Silver Ions, Copper (II)-Ammonia, Chromate-Dichromate, Iron (III Chloride-Thiocyanate, and the Cobalt (II) Ions systems.
In this experiment, five systems were prepared. The first one was the Iron (II)-Silver Ions System. It was done by mixing first approximately 1ml each of...
References: Petrucci, Ralph H.,William S. Harwood, and Geoffrey F. Herring (2002). 8th edition.
Masterton, William L. Cecile N. Hurley, and Edward J. Neth (2011). 7th edition. Chemistry: Principles and Reactions. CENGAGE Learning.
Equilibrium Constants. http://www.ausetute.com.au/equicons.html Retrieved last: April 24, 2012.
K2K1’ = K = (9.77x1012)(37)
K = [Cr2O72-] = 3.61x1014
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posted by Sabia
what are two distinguishing characteristics of prokaryotes?
- Ms. Sue
they range in size from 1 to 5 micrometers
Prokaryotes does not have well defined nucleus and does not have well defined cell membrane. Differences in cellular structure of prokaryotes and eukaryotes include the presence of mitochondria and chloroplasts, the cell wall, and the structure of chromosomal DNA. | <urn:uuid:fa6f0f2b-f9cb-4a66-ba3f-7b85c1727cf1> | 3.203125 | 90 | Q&A Forum | Science & Tech. | 30.87 | 95,632,027 |
A View from Emerging Technology from the arXiv
The Challenge of Putting Astronauts on a Near-Earth Asteroid
Finding a near-Earth asteroid worth landing on is harder than it seems, say rocket scientists.
What next for the human exploration of space? One idea is to send the next generation of astronauts to explore a near Earth asteroid.
Let’s set aside, for a moment, the question of whether human exploration of space is viable and look at the supposed benefits of visiting a passing rock.
First, asteroids are of enormous scientific interest, being remnants of the primordial Solar System. Second, they need to be well-characterised so that we can head one off should it ever come our way. And finally, they may provide the raw materials and resources for future missions which can use them as stepping stones to Mars and beyond.
But what makes near Earth asteroids particularly inviting from an engineering point of view is their small velocity relative to Earth. A small delta-V, as rocket scientists call this, means less fuel and more payload. And that translates into longer missions with a better scientific return.
That raises an obvious question: which asteroid do we aim for?
Today, Martin Elvis at the Harvard-Smithsonian Center for Astrophysics in Cambridge and a few buddies examine the possibilities. It turns out that of the 6699 near-Earth asteroids we know, only half a dozen have a delta-V worth considering and are big enough to land on (unless we want to land on an asteroid that is smaller than spacecraft visiting it).
Of course, there are many other near-Earth asteroids that we haven’t discovered, probably an order of magnitude more.
But finding them is particular problem. Their very proximity in an orbit similar to Earth’s means that they spend much of their time on the other side of the Sun and in any case are mainly visible only from Earth’s day-side. That makes them almost impossible to see and track from the ground.
So not only do we have a embarrassing of poverty of choice when it comes to deciding which to visit, there is not much prospect of increasing it in the near future.
And if that weren’t bad enough, human spaceflight is about to come to a sudden end in America. In a few weeks, NASA won’t be able to visit the even International Space Station little more than 200 miles above the surface. And yet it has tentative plans to visit a near Earth Asteroid in 2025 or so.
Even now, this looks ambitious. Robots anyone?
Ref: arxiv.org/abs/1105.4152: Ultra-Low Delta-v Objects and the Human Exploration of Asteroids
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- Research article
- Open Access
Removal of heavy metals from aqueous solution using platinum nanopartcles/Zeolite-4A
© Mehdizadeh et al.; licensee BioMed Central Ltd. 2014
Received: 1 October 2012
Accepted: 15 October 2013
Published: 7 January 2014
The effects of varying operating conditions on metals removal from aqueous solution using a novel platinum nanopartcles/Zeolite-4A adsorbent are reported in this paper. Characterization of the adsorbent showed successful production of platinum nanopartcles on Zeolite-4A using 3 Wt% platinum. The effects of operation conditions on metals removal using this adsorbent were investigated. The optimal metals adsorption was observed at pH 7, 0.1 g/10 mL dosage and 30 min contact time. Sorption data have been interpreted in terms of Langmuir and Freundlich isotherms.
Water contaminated by heavy metal ions had become much more serious with a rapid development of industries and competitive use of fresh water in many parts of the world . Heavy metals are not biodegradable and tend to accumulate in living organisms, causing various diseases and disorders [2–4].Therefore, the removal of heavy metal ions from water has become an important subject today.
Several conventional methods exist for the removal of heavy metal pollutants from wastewater. These methods include precipitation, electroplating, chemical coagulation, ion-exchange, membrane separation, and electro kinetics. However, most of these methods have limitations, which include high cost, unavailability, and generation of large volumes of secondary waste and poor removal efficiency [5–7]. Considering from the economy and efficiency point of view, adsorption is regarded as the most promising and widely used method among all these . The efficiency of adsorption depends on many factors, including the surface area, pore size distribution, polarity, and functional groups of the adsorbent . One of the main limitations of the sorption techniques is the massive mass transport resistance due to the size of the adsorbents. To overcome this limitation, the use of new adsorbents has attracted considerable attention in recent years.
The application of nanotechnology to the purification and treatment of wastewater may potentially revolutionize water treatment processes because of their unusual physical and chemical properties owing to their extremely small size and large specific surface area. Due to these characteristics, nanomaterials have found wide applications in adsorption and the removal of heavy metal ions from aqueous solutions .
Zeolites are microporous crystalline solids with well-defined structures, which have unique ion exchange and sorption properties, and are widely used in a large number of water treatment processes .
The objective of the present study is to investigate the adsorption potential of Pt on zeolite in the removal of heavy metal ions from aqueous solution. The effects of pH, adsorbent dosage, contact time and temperature on adsorption capacity of Pt/Zeolite have been investigated. The Langmuir and Freundlich isotherms models are applied to the sorption data to calculate the different parameters and the best fittings achieved.
Material and instrument
The particle size of the nanocrystalline particle was examined using transmission electron microscopy (TEM, Philips EM208S at 100KV). The X-ray diffraction (XRD) pattern of the catalyst powders was provided by a (Philips PW 1800) diffractometer. To determine the concentration of component, Inductively Coupled Plasma (ICP, Perkin Elmer 5500) was used. Different pH of Samples was measured with pH meter (Schott CG-841) and centrifuge (Beckman J-21C device) was applied for separating solid particles from the solution. The Shaker bath (Infors AG) was used for the stirring system at constant temperature to determine the distribution coefficients.
Zeolite4A were obtained from Pars zeolite Co. (Tehran, Iran) and Hexachloroplatinic acid: H2PtCl6.6H2O (99.9%, metals basis) and Poly vinylpyrrolidone (PVP, Mw= 29 000) was purchased from Merck All the compounds used to prepare the reagent solutions were of analytic reagent grade. The heavy metal ions solutions containing 50, 100, 250 and 500 mg/L each of La3+, C02+, Ba2+ and Ni2+ ions were prepared by dissolving a weighed quantity of the respective nitrate salts in distilled water.
Synthesis of the platinum nanoparticle
The synthesis procedure was started by adding 133 mg PVP into a mixture of 20 cm3 of 6.0 mM H2PtCl6.6H2O aqueous solution and 180 cm3 pure ethanol. The mixture then was refluxed for 3 h. Afterward, the solvent was evaporated, and the obtained black precipitate was thoroughly washed with water and ethanol, and dried at ambient condition.
Preparation of Pt/Zeolite
About 20 cm3 of H2PtCl6.6H2O aqueous solution (6 mM) was mixed with 133 mg PVP and 180 cm3 of ethanol. The mixture was quickly added to 1.5 g of the zeolite 4A, and refluxed for 3 h. The solvent then was evaporated and the obtained granules were calcined at 450°C for 12 h in a stream of muffle furnace.
Batch adsorption experiments
Where Ci and Ce are the initial and final metal ion concentrations, respectively.
Results and discussion
Preparation and characterization of adsorbent
4A with a pore diameter of 9.0 nm was used as a support due to its high surface area and ordered mesoporous structure. Platinum/zeolite adsorbent was prepared as discussed in section 2. The loading of the platinum on the zeolite sample was measured by dissolving the sample in aqua regia, and analyzing of the Pt content of the supernatant by ICP method. The loading was found to be around 3 Wt%.
The removal efficiency (R%) of the metal ions on Pt/zeolite 4A with zeolite 4A
To optimize the adsorption system, the effects of various parameters such as adsorbent dose, pH, and time on the adsorption of Co (II), Ba (II), La (III) and Ni (II) ions were studied.
Effect of adsorbent dosage
Effect of contact time
Effect of pH on adsorption
At low pH the concentration of protons was high and metal binding sites became positively charged repelling the Co (II), Ba (II), La (III) and Ni (II) cations. With an increase in pH, the negative charge density on the adsorbent increases due to deprotonation of the metal binding sites, thus increasing metal adsorption. The maximum adsorption observed in the pH 7 and the subsequent reduction in adsorption capacity was probably due the partial hydrolysis of metal ions. Furthermore, the low solubility of hydrolyzed metals species would have resulted into precipitation of metals at pH above 7, thereby reducing adsorption capacity of Pt/zeolite 4A.
The adsorption isotherms are very important in describing the adsorption behavior of solutes on the specific adsorbents. In this work, two important isotherm models such as Langmuir and Freundlich were selected and studied.
where qe (in mg/mg) is the adsorbate amount adsorbed by 1 g of adsorbent, Ce (in mg/L) is the equilibrium concentration of adsorbate in the solution, Qo is the monolayer adsorption capacity (mg/mg), b is the constant related to the adsorption intensity, Kf is constant indicative of the relative sorption capacity of Pt/zeolite 4A (mg/g) and 1/n is the constant indicative of the intensity of the sorption process.
Isothermal adsorption models for the adsorption of Co (II), Ba (II), La (III) and Ni (II) adsorption on Pt/zeolite 4A
K f (mg/g)
It was observed that results fitted better in the Freundlich model in terms of the correlation factor (R2) value, recording 0.99 for Ba (II) and the higher Langmuir correlation factor (R2) values of 0.996, 0.992 and 0.983 for the adsorption Co (II), La (III) and Ni (II) respectively, strongly suggests that the Langmuir model gives a better fit to the experimental data and so the nature of adsorption of metal ions on the adsorbent is more compatible with Langmuir assumptions.
Pseudo-second order kinetic parameters for Co (II), Ba (II), La (III) and Ni (II) ions onto Pt/zeolite 4A
The removal of heavy metals from aqueous solution was carried out in a batch adsorption mode using platinum nanopartcles/Zeolite-4A adsorbent. The platinum nanopartcles/Zeolite-4A exhibited effectiveness in the removal of Co (II), Ba (II), La (III) and Ni (II) ions from aqueous solutions. The removal efficiency was controlled by solution pH, adsorbent concentration and contact times. Adsorption data fitted well with the Freundlich model for Ba (II), while Langmuir isotherm adsorption model having higher R2 value for Co (II), La (III) and Ni (II) ions, described the adsorption process better than Freundlich model for the three metals. This novel material opens new door for various usage of the nanomaterials in different fields of application in the wastewater treatment.
The author is thankful from Nuclear Science and Technology Research Institute and Department of Energy Engineering of Sharif University of Technology for the financial support of this project.
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This article is published under license to BioMed Central Ltd. This is an open access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. | <urn:uuid:b0758f73-ea2c-4854-877a-a9aa96a029fd> | 2.515625 | 3,121 | Truncated | Science & Tech. | 48.848571 | 95,632,082 |
The Hydrological Effects of the January 94 Bush Fires on the Royal National Park
- The Institution of Engineers, Australia
- Publication Type:
- Conference Proceeding
- Proc. 28th International Hydrology and Water Resources Symposium, 2003, 2 pp. 161 - 168
- Issue Date:
Previous research into the hydrological effects of fire have found that runoff increases immediately after the fire. This was attributed to the removal of vegetation and a decrease in the initial losses associated with rainfall. Another possible cause for the increase in runoff is heat treating of. the soil as the fire scorches the soil and there is a resultant decrease in the ability of the water to infiltrate. After this initial period of increased runoff, the conversion of rainfall to runoff has been reported to decrease. This decrease in runoff has been attributed to increases in the evapo-transpiration losses of the forest. In January 1994, Sydney was surrounded by a number of wild fires. The Royal National Park which is located to the south of Sydney is one of the areas burnt by these bush fires. For a number of years, SCEE UNSW has operated and maintained a network of pluviometers and stream flow gauges within the Upper Hacking Catchment, which lies within the Royal National Park. During the January 1994 bush fires approx 30% - 40% of the monitored catchment was burnt. Analysis of pre and post fire daily totals was undertaken for the catchment to assess the impact of the fire. Excessive change in the rainfall-runoff relationship of the catchment determined through the lnltlal.analysls lead to the investigation of other parameters affecting the hydrology. It was shown that changes in the rainfall-runoff relationships due to the fire are interrelated to the changes in the rainfall-runoff relationship due to the onset of drought. Furthermore, it was shown through investigation of two catchments that changes in the rainfall-runoff relationships in both catchments were similar. Consequently, it was concluded that for the Royal National Park, the impacts of bush fires on the rainfall-runoff relationship are interrelated to the impacts of the drought on the rainfall-runoff relationship.
Please use this identifier to cite or link to this item: | <urn:uuid:3bb676df-4544-4710-9594-2ed12e5c24c0> | 2.875 | 457 | Academic Writing | Science & Tech. | 38.489073 | 95,632,088 |
While spring is known for its dangerous thunderstorms that can produce violent tornadoes, fall can also feature an uptick in severe storms and is considered the second severe weather season.
(MORE: Tornado Central)
A secondary peak in tornado activity occurs in the fall in the Gulf Coast states, where temperature and humidity levels tend to be higher. These conditions can sometimes spread north to the Ohio Valley and southern Great Lakes.
Despite May being the peak month for tornadoes, six of the largest 55 known tornado outbreaks occurred in October and November, according to storm statistics compiled by The Weather Channel severe weather expert Dr. Greg Forbes.
October and November's tornadoes are caused by upper-level troughs, or southward dips in the jet stream, and cold fronts affecting the South and sometimes the Midwest.
The map below shows how many tornadoes have been confirmed by the National Weather Service during the month of November from 1950 through 2014. Texas has the highest number, but when adjusted for total area, Mississippi has the most, followed closely by Louisiana and Alabama.
On rare occasions, weak tornadoes can form on the West Coast in November, extending into the core winter months.
In December, the highest chance for tornadoes moves back to the South, where the warmest air and much of the moisture is located.
The jet stream also begins to migrate south for the winter months, but dips in the jet stream farther north behind abnormally warmer weather can spell trouble into the Tennessee Valley and East Coast.
Late-season tropical cyclones can also give a boost to tornado activity along the Gulf Coast in late fall and early winter.
Biggest Second-Season Tornado Outbreak: Nov. 21-23, 1992 – 105 Tornadoes
- States affected: 13 total, from Texas to the Carolinas.
- Twenty-six people were killed and 638 were injured.
- The outbreak caused $713 million in damage; the Houston area was hit especially hard.
- It was rated a top-five worst tornado outbreak in any month since 1950 by Dr. Forbes.
This outbreak started the Saturday before Thanksgiving 1992 in Houston. An incredible seven tornadoes were spawned in the span of just two hours in the metro area, with three twisters on the ground at the same time in Harris County. The strongest tornado, rated F4, destroyed more than 200 homes on Houston's east side. This was the strongest tornado to hit the Houston metro since 1950.
Another F4 tornado went on a 128-mile rampage through Mississippi overnight Saturday into Sunday morning, Nov. 22. The storm claimed 12 lives and damaged or destroyed more than 700 homes.
Fifteen tornadoes touched down in Indiana that Sunday – the largest November outbreak in state records. One tornado was an F4 in southeastern Indiana and northern Kentucky. Other F4 tornadoes carved a swath through the far northwestern suburbs of Atlanta and also struck near White Plains and Lake Oconee, Georgia.
Finally, a pair of F3 tornadoes in North Carolina killed two and injured 59. | <urn:uuid:2f56bf93-b4fe-40e1-8e33-8362660ba4e0> | 3.8125 | 617 | News Article | Science & Tech. | 50.687034 | 95,632,089 |
Concave polygons are polygons for which a line segment joining any two points in the interior
lies completely within the figure
The word interior is important. You cannot choose one point inside and one point outside the figure
The following figure is concave:
Segment AB does not entirely lie within the polygon. That is why the polygon is concave
Notice that it is quite possible to find other segments that will lie inside the figure, such as segment FE.
However, if you can find at least one
segment that does not lie within the figure, the figure is concave
The following figure is also concave
It is easy to construct a concave figure if the figure has at least 4 sides
Just make sure that one interior angle is bigger than 180 degrees.
In other words, an interior angle should be a reflex angle
Why am I saying at least 4 sides? It is possible to make a concave triangle?
The answer is no!
Since the sum of the interior angles in any triangle must add up to 180 degrees, no interior angles can be more than 180. It is impossible!
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Volcanoes become active when fluids are in motion, and erupt when these fluids escape into the atmosphere. Volcanic fluids are a mixture of solid, liquid and gas. These mixtures result in a complex range of flow behaviour, especially during interaction with conduit geometry. These processes are not directly observable and must be inferred from interpretations of field observation and measurement. One of the outcomes of this complexity is the generation of pressure and force transients as high-density phases accelerate and decelerate during unsteady flow. These transients are one means of flexing the conduit wall, a process that manifests itself as ground motion and is detectable as volcano seismic signals. On eruption, volcanic fluids interact with the atmosphere and generate acoustic and thermal signals. In this Special Publication we present a series of papers based on field, numerical and experimental approaches that seek to establish links between geophysical signals and fluid motion in volcanic conduits.
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Keywords are predefined reserved identifiers that have special meanings. They cannot be used as identifiers in your program. The following keywords are reserved for Microsoft C++. Names with leading underscores are Microsoft extensions.
1 Extended attributes for the __declspec keyword.
2 Applicable to Managed Extensions for C++ only. This syntax is now deprecated.
3 Intrinsic function used in event handling.
See Component Extensions for Runtime Platforms for more information.
In Microsoft C++, identifiers with two leading underscores are reserved for compiler implementations. Therefore, the Microsoft convention is to precede Microsoft-specific keywords with double underscores. These words cannot be used as identifier names.
Microsoft extensions are enabled by default. To ensure that your programs are fully portable, you can disable Microsoft extensions by specifying the ANSI-compatible /Za command-line option (compile for ANSI compatibility) during compilation. When you do this, Microsoft-specific keywords are disabled.
When Microsoft extensions are enabled, you can use the Microsoft-specific keywords in your programs. For ANSI compliance, these keywords are prefaced by a double underscore. For backward compatibility, single-underscore versions of all the double-underscored keywords except __except, __finally, __leave, and __try are supported. In addition, __cdecl is available with no leading underscore.
The __asm keyword replaces C++
asm is reserved for compatibility with other C++ implementations, but not implemented. Use __asm.
The __based keyword has limited uses for 32-bit and 64-bit target compilations.
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The Daily Dinosaur Media
October 9, 2007
Dinosaur discoveries continue to make news. Here are some recent findings by those who dig getting out and digging for what they can get out: Giant Ascending the Grand Staircase: A new species of duck-billed dinosaur was found in the Grand Staircase-Escalante National Monument, reported Science Daily, EurekAlert, Live Science and National Geographic. High school […]
Was Velociraptor a Dragon?
September 22, 2007
As if Velociraptor, the terror of Jurassic Park, was not scary enough, some scientists are now saying it was feathered. (This, of course, does not imply it could fly after its human prey like some movie dragon.) The latest claim in Science is based on the apparent presence of “quill knobs” on the radius bone […]
Dinosaurs Stretched, Shrunk and Twisted Into Birds
September 6, 2007
Size matters, thought paleontologists envisioning the evolution of birds from dinosaurs. The old story was that dinosaurs shrunk as their arms were becoming wings. That view has been challenged by a new fossil reported in Science.1 Alan H. Turner (American Museum of Natural History) and four others reported a “basal dromeosaurid” that was small long […]
Largest Dinosaur Mass Grave in Switzerland Found
August 15, 2007
As many as 100 plateosaurs may be buried in a mass grave in Switzerland, reported the Reuters news service. “The finds show that an area known for Plateosaurus finds for decades may be much larger than originally thought” – as much as a mile in width in the town of Frick, near the German border. […]
Dinosaur Sex and Other Tales
July 24, 2007
How much do we really know about dinosaurs? How much can be inferred from their bones? Two recent stories illustrate conflicting themes: much of what we thought we knew was wrong, but that doesn’t stop evolutionary paleontologists from speaking with confidence. Walking with dino ancestors: Paleontologists used to think that the alleged precursors of dinosaurs […]
Chinese Eat Dragon Bone for Health
July 4, 2007
Chinese villagers dig up dinosaur bones for health food. Yahoo News reported, “Villagers in central China dug up a ton of dinosaur bones and boiled them in soup or ground them into powder for traditional medicine, believing they were from flying dragons and had healing powers.” The article says the bones are calcium rich and […]
Imaginary Dinosaur Feathers Found Again!
June 13, 2007
Last year, we reported that imaginary feathers had been found on a dinosaur fossil (see 02/08/2006). Now, more imaginary feathers have turned up. This turkey was big, too: the dinosaur plumed in the imaginary feathers stood almost 12 feet tall. Everyone’s talking about it: Fox News, MSNBC News and Science News among others. National Geographic […]
Dino Feathers or Horsefeathers?
May 23, 2007
The much-touted feathers on certain dinosaurs may be nothing more than collagen fibers. An article on ABC France says “Dinosaur ‘feathers’ are no such thing.” Instead, it’s just decayed dermal collagen, like that found on sharks and reptiles. A South African team came to this conclusion after analyzing the alleged feathers on Sinosauropteryx. […]
Jurassic Park Gets Overhaul
April 17, 2007
How much do we understand the dinosaurs? ABC News reported on some big-time updates and revisions being made to the Carnegie Museum of Natural History dinosaur exhibits. The title of the article is, “Getting Their Dinosaur Facts Right, at Least for Now.” The problem is that even though the newest of the dinosaurs are 65 […]
Proteins Found Preserved in T. rex Bone
April 12, 2007
Preserved fragments of collagen have been found in a dinosaur bone alleged to be 68 million years old. Read all about it in Science Daily. Analysis of soft tissue found by Mary Schweitzer and team turned up the recognizable protein fragments. Protein was also detected in soft tissue from a mastodon said to be half […]
New Dinos Found; What Do They Mean?
March 27, 2007
There is often a wide gap between the bones that are found and the stories that are told about them. As new dinosaur bones come to light, some reporters cannot resist imagining all kinds of things about their lifestyles. Here are two recent examples. As a bonus, we’ll add a non-dinosaur reptile story or two. […]
Evolutionary Predictions Fail Observational Tests
March 8, 2007
Lately, some expectations by evolutionists have not been fulfilled. Here are several recent examples of evolutionary upsets: Dinobird genes cook up scrambled eggs: Scientists expected that the dinosaurs presumed ancestral to birds would show a decreasing genome size. The thinking was that the cost of maintaining a large genome takes its toll on flight. In […]
Dino Horns: Is Smaller More Evolved?
March 5, 2007
One can never tell which way the evolutionary path will take to determine fitness. Could be bigger, could be smaller. Could be faster, could be slower. Could be better camouflaged, could be flashy. Michael Ryan (Cleveland Museum) decided that shorter horns on his dinosaur constituted better fitness. CNN says his discovery, a 20-foot dinosaur in […]
First Euro-Stegosaur Found
February 4, 2007
A Stegosaurus fossil has been found in Portugal, reported Live Science. Previously this species with its spiked tail and prominent rows of plates on its back was only known from North America. A tooth, some leg bones and part of the backbone have been unearthed. So far, the fossil looks indistinguishable from its North American […]
Dinosaur Fight or Common Fate?
January 17, 2007
A fossil discovery by amateurs in Montana, reported by the Great Falls Tribune, shows “a meat-eater and a plant-eater – with their tails crossed like swords.” The fossils show “remarkable detail, right down to tendons and teeth.” The three amateur discoverers had been scouting on private property in Garfield County. Finding bone fragments on a […] | <urn:uuid:0cfa8aec-fbc8-452c-a323-5c5e420033d4> | 2.609375 | 1,311 | Content Listing | Science & Tech. | 49.415048 | 95,632,145 |
Is equation solvable on the set of integers Z?
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Preliminary observations of dayside high latitude ionospheric plasma convection with the Sondrestrom incoherent‐scatter radar indicate that plasma can be observed to enter the polar cap region through rotational reversals at most local times between dawn and dusk and not just in a narrow region around noon. Assuming that rotational reversals are signatures of a solar wind‐magnetosphere interaction which drives magnetospheric convection, the observations indicate that this interaction occurs over a longitudinally wide area of the dayside magnetosphere. The observations also show that the distribution of F‐region plasma in the polar cap is dependent on ionization sources anywhere between dawn and dusk in the dayside high latitude ionosphere.
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Citation InformationJorgensen, T. S., E. Friis‐Christensen, V. B. Wickwar, J. D. Kelly, C. R. Clauer, and P. M. Banks (1984), On the reversal from “sunward” to “antisunward“ plasma convection in the dayside high latitude ionosphere, Geophys. Res. Lett., 11(9), 887–890, doi:10.1029/GL011i009p00887. | <urn:uuid:122b0740-8566-4a9a-a782-ccf1d6fc4a19> | 2.53125 | 295 | Academic Writing | Science & Tech. | 36.119047 | 95,632,170 |
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The future is huge for tiny technology. Miniaturization is, perhaps ironically, a huge deal. I mean, without it we wouldn't have had the personal computer revolution and we wouldn't have this world we live in now, where we have smartphones and tablets and other devices just as powerful as a computer, that can fit in the palm of your hand. But even these gadgets are gargantuan compared to nanotechnology! See, a nanometer is just one billionth of a meter. And that's kind of hard to imagine, so let me put it to you this way.
Your typical sheet of paper is about one hundred thousand nanometers thick. And at this scale, individual elements are so small you can't even see them with a light microscope. Now as we learn more about how materials behave on the nanoscale, we have more potential applications to use that knowledge practically. I'm talking about how nanotech could help solar panel technology. And fortunately, at a recent meeting of the American Association for the Advancement of Science, or AAAS, they had a panel on just this very subject. Now if you know anything about solar panels you know they have some drawbacks. For example,.
Efficiency they max out at around twenty percent in the field under ideal conditions. They're also rigid, so you can't just put them anywhere you like. And they tend to be expensive because manufacturing them is complicated. But scientists hope that nanotechnology can help address all three of these challenges. Now with efficiency they're looking to nature specifically, moth eyes. You see, moths have these little tiny structures in their eyes that help reflect light back into the eye and it does two things it lets them see better in the dark, and it cuts down.
On reflection so predators can't spot them as easily. With solar panels it could actually make them more efficient by reflecting more of the sun's light into the panel so you lose less in reflection. And when we're talking about flexibility, well nanomaterials are really, really small, and there is the potential to create solar panels that are just a few sheets of molecules thick. They could be as flexible as a sheet of paper, and with that kind of flexibility you could put those pretty much anywhere you wanted to.
And as for price, well, that's the big one. And in the short term I don't think it's going to turn around. But scientists are cautiously optimistic that nanotechnology will let us use new processes, like printing solar panels directly onto a substrate using just a specialized printer. That would actually be less complicated and expensive than traditional manufacturing methods. Now at that meeting of the AAAS, a Dr. Wolfgang Porod gave a talk about Nanoantenna Thermocouples for Energy Harvesting. Which I admit sounds like technobabble straight out of a Star Trek episode.
But it's actually fairly simple once you break it down. A nanoantenna is just an antenna on the nanoscale. These resonate with longwave infrared radiation. And a thermocouple Well that's a component of circuitry that generates a voltage when one part of the thermocouple is a different temperature than other part. So you pair these two together and the antenna generates heat and the thermocouple generates voltage. It could actually help increase the efficiency of solar panels. Now like I said, nanotechnology is a young science and it has lots of different applications.
Across many disciplines. And I'm really excited how such a small technology could have such a huge impact. That leads me to this week's question. When I say the word nanotechnology what do you imagine What does that word mean to you Let us know in the comments below. Then, do me a nanosized favor and share this tutorial with your friends. If you enjoyed it make sure you hit the 'like' button and subscribe to our channel. Then check out these tutorials over here. There's some huge surprises in them.
What Countries Are The Most Energy Efficient
As emerging economies continue to expand, their energy needs are set to grow dramatically in the coming years. The International Energy Agency has even predicted that global energy use will increase by 30 percent over the next two and a half decades. With crude oil the source of so much volatility around the world, there is no question that the the future of energy will be based on countries dedicated to alternative, renewable sources. So, which countries are the most energy efficient Well, the American Council for an EnergyEfficient Economy has ranked the world's 16 largest.
Economies, which account for nearly three quarters of global electricity consumption. This is based on 31 metrics, spanning energy use in buildings, industry, and transportation. It includes things like the country's national energy savings goals, vehicle fuel economy standards, and energy consumed per foot of floor space. The United States ranks among the least efficient, at number thirteen. But across the board, Germany saw the greatest energy efficiency, scoring well in all metrics, but especially industry. According to the report, German industry and manufacturing is the second most fuel efficient in the world, with plans to far surpass the current leader,.
Australia, by 2020. Part of the reason Germany is doing so well is a national policy, dedicated to lowering energy use, known as Energiewende, or Energy Transition. The goal of this program is to stop using coal and other nonrenewable energy sources like oil. Clearly, it has been working so far. In 2014, Germany accounted for half of the new wind farms in the EU, and has been leading the world in energy efficiency. In an extremely close second place overall, Italy actually surpasses Germany in transportation. Although they tie with the UK for vehicle fuel efficiency, at nearly 40 miles per gallon.
On average, Italians also travel the least per capita. This low impact, high efficiency makes Italy a world leader in transit energy. Additionally, Italy tends to prioritize its rail system over its roads, leading to more people taking the train, and thereby saving considerable energy. Still, Italy continues to primarily use fossil fuels, and actually scores the worst in terms of commercial building energy efficiency. When it comes to buildings, China takes the lead. Their polluting past and wide range of energy inefficiency may hold them back. But China's residential buildings use less.
Energy per square foot than any other country in the report. This is partially due to strict building codes, and the fact that energy intensity is one of the country's top priorities. And despite being known for wastefulness, between 1980 and 2010, energy consumption increased five times, while the economy grew 18 times. Between Germany, Italy, and China, emerging countries can look at their journeys towards energy efficiency, and fine tune their own programs for maximum output. Still, every country surveyed has a long way to go, and plenty of areas to improve. Hopefully, 2016.
SolarCity Unveils Worlds Most Efficient Rooftop Solar Panel with more than 22 Module Efficiency.
The Sun provides endless energy, but the average solar cell panel can convert only 14 to 20 of the energy it collects into usable electricity. Now, American energy company SolarCity has built the world's most efficient rooftop solar panel, with a module efficiency exceeding 22 percent. The new SolarCity panel generates more power per square foot and harvests more energy over a year than any other rooftop panel in production, and will be the highest volume solar panel manufactured in the Western Hemisphere. SolarCity will begin producing the first modules in small quantities this month at its 100.
MW pilot facility, but the majority of the new solar panels will ultimately be produced at SolarCity's 1 GW facility in Buffalo, New York. SolarCity expects to be producing between 9,000 10,000 solar panels each day with similar efficiency when the Buffalo facility reaches full capacity. SolarCity's panel was measured with 22.04 percent modulelevel efficiency by Renewable Energy Test Center, a thirdparty certification testing provider for photovoltaic and renewable energy products. SolarCity's new panel is created via a proprietary process that significantly reduces the manufacturing cost relative to other highefficiency technologies, and it.
Los Alamos Discovers Super Efficient Solar Using Perovskite Crystals
Aditya Mohite Our group focuses on converting solar energy into electricity. And we're working on a class of solar cells which are referred to as third generation solar cells. The goal of our project was, how do we take these materials and control their crystalline properties, crystalline size, and get them to a point which are comparable to what is used in daytoday semiconductor industry like gallium arsenide or silicon. We're not there yet, silicon is the holy grail, but one of the biggest advantages of this material, at least from what we've begun to discover, is that you can make very high.
Quality crystals off this material which are large area, they are single crystalline, and they have properties which are at par with silicon or gallium arsenide. There's a lot of work that needs to be done in the engineering aspect of things, in terms of the stability you're trying to get, the right electrical contacts for them to perform at par with silicon, but I would say that this is something which will be achieved in the coming years. Wanyi Nie So, we developed a new technique, it's called the hot casting process, where we keep.
Our substrate hot and solution hot and do the spincoating at elevated temperature and at the same time the film color will be converted from light yellow to dark brown which means we're forming a highquality crystalline grain, and if we look at it under the microscope we are able to achieve up to millimeter scale large crystal grains. Normally for the crystals to grow usually require high temperature or sophisticated processing, but this method is kind of low temperature and easy solution processing. Mohite There has always beena lot of defects and disorder and multiple interfaces.
That has plagued efficiencies, and so by growing these crystals of highquality you have sort of circumvented that problem and solved an important bottleneck which has existed in this field of nanomaterial, solutionbased solar cells, third generation solar cells. Solar energy is trying to tap into the unlimited amount of solar energy that falls on Earth and that's basically free, and if you can harvest that at a very, very low cost, much cheaper that what is used, by burning coal for example, and fossil fuels, then that gives us a route to really be completely energy.
Renewable Energy Efficiency
You can never take no for an answer. When people say things can't be done you really have to be very skeptical and sometimes it requires a lot of perseverance to get through the no's. Energy is the lifeblood of America and indeed any nation. The more we as a nation and in fact avoid the use of our energy and actually produce it home, improves our energy security worldwide and actually increases our economic competitiveness and our environmental quality. When we started this process nobody thought it was possible to build a super energy efficient building that.
Could achieve netzero energy with the amount of money we had and what it required really was to change the way we look at the design process, to bring people in the design process up front and early. The success in this building is really driven by its ability to achieve that 50 percent energy efficiency standard and we can actually add that photovoltaics to make it zero energy. This building is about 20 percent recycled materials including concrete from the now disassembled Stapleton airport. One of the things you'll notice when you walk into the building is that every workspace is.
Day lit. In fact, a 100 percent of our space is day lit. Nobody is more than 30 feet from a window. Other highlights of the building, there's no heating or air conditioning in the traditional sense. It uses evaporative cooling to, in fact, chill water. Out heat is provided by what's called the renewable fuels heating facility, where we actually burn biomass to generate hot water. The big feature of the building is using water to, in effect heat and cool the building. Which is much, much more energy efficient. The uprights of the building.
Are actually natural gas pipes that have, in effect, been reconditioned to provide the structural framework for the building. The advantage that we have by incorporating all these materials and techniques is that, again, we produce a highly energyefficient building, it's gonna save us money over the long run as we operate it, since we're only paying about half as much for utilities costs but the other benefits that we've created by doing this process is that we've made a space it is much more fun to work in. Lots of studys show that if people have access to day light.
Developing the Most Efficient Solar Panels DuPont Solamet and Sharp Corporation
00011000,00015000 gtgt Tetsuro Muramatsu For Japanese people it is very important to coexist with nature. 00021500,00032500 gtgt Nobuyuki Morioka Solar energy has been my life's work. I have installed panels for 40 years now. The power source at Tsubosaka Temple is one of many I have installed. 00040500,00040500 gtgt Minoru Amoh Together with Sharp, we are aiming to achieve the best energy conversion in the world. 0004800,00057500 gtgt Minoru Amoh We believe we can achieve this with New Crystalline Solar Cells. The thought behind New Single Crystalline Solar Cells is that higher conversion efficiency can be achieved by grouping the.
Electrodes together underneath to ensure nothing blocks out the sunlight. 00102500,00112000 gtgt Minoru Amoh DuPont created highly reliable, precision surfaceink printing. Without this kind of relationship with Sharp,this technology could not be realized. 0011500,00121000 gtgt Nobuyuki Morioka I am about to retire. I hope that the good work with this type of cleaner energy will continue. 00127000,00130500 gtgt Motohiro Suzuki I think we will see an increase of solar panels in the future. 00132000,00137000 gtgt Motohiro Suzuki My first installation of New Single Crystalline Solar Cells was at this 24hour convenience store.
New solar system for improved energyefficiency
Finding creative solutions to energy issues and energy efficient buildings has become a major priority for Europe in recent years. Today simple, nonpolluting technologies are deployed quickly. This industrial building in Malta hosts the prototype of an EUfunded optical system developed in the framework of the European project DiGeSPo. Its Concentratedsolar technology will be used to produce heat and electricity. The system uses mirrors with a tracking system to focus sunlight onto a receiver which contains a heat transfer fluid. The EU is aiming for a 20 cut in Europe's annual.
Energy consumption by 2020. Digespo is contributing to that objective by developing a new solar technology. The prospects of strong growth for Concentrated Solar Power over the next few decades seem good. This will help develop a competitive industry and foster EU partnerships. As we are all aware, there are about 160 million buildings within Europe. We see this as a unique challenge to be one of those buildings where we can generate energy efficiencies and energy improvements. Houses and buildings consume up to 40 of total EU energy use. Digespo and its mini solar power systems will.
In the long run allow homes and workplaces alike to generate their own electricity and meet their heating and cooling requirements. The Digespo project is a fantastic opportunity to exploit the huge potential and solar resources especially on an island like ours or in the Mediterranean region but also a very good opportunity for us to transfer knowledge which is mostly acquired from mainland Europe and solar research to the Mediterranean region in general. This is just the beginning As we become bigger consumers of energy, the European consortium of the DiGeSPo project wants.
Making Solar Energy More Affordable, Efficient
Siliconbased solar cells are the rule, but a University of NebraskaLincoln scientist hopes to change the industry standard using new materials and manufacturing methods. Jinsong Huang's research has been featured in the magazine, Science, and is supported by the National Science Foundation and the U.S. Department of Energy. Huang makes solar cells using perovskite, a material with a crystal structure that has proven almost as efficient as silicon, but much less expensive. Thin layers of material are applied using a technique called spin coating. The next step is to demonstrate the device is stable.
Saving Energy with Solar Power Designing Windmill Blades for Energy Efficiency
The other thing is, when you want to build one, it's very difficult to get the right shape of the blades because these blades have to be very carefully designed that they get most out of it. You would not believe it, but when you see it here, these blades are spinning 3 times faster than the wind. Why Because of the design of the blades, they can spin faster than the wind is blowing. The windmill by itself will start producing electricity with about 6 to 7 miles per hour and then it goes up and gets its peak, its.
Energy 101 Concentrating Solar Power
Bjbj Take the natural heat from the sun, reflect it against a mirror, focus all of that heat on one area, send it through a power system, and you've got a renewable way of making electricity. It's called concentrating solar power, or CSP. Now, there are many types of CSP technologies. Towers, dishes, linear mirrors, and troughs. Have a look at this parabolic trough system. Parabolic troughs are large mirrors shaped like a giant U. These troughs are connected together in long lines and will track the sun throughout the day. When the sun's heat.
Is reflected off the mirror, the curved shape sends most of that reflected heat onto a receiver. The receiver tube is filled a fluid. It could be oil, molten salt something that holds the heat well. Basically, this super hot liquid heats water in this thing called a heat exchanger and the water turns to steam. The steam is sent off to a turbine, and from there, it's business as usual inside a power plant. A steam turbine spins a generator and the generator makes electricity. Once the fluid transfers it heat, it's recycled and used over and over.
And the steam is also cooled, condensed and recycled again and again. One big advantage of these trough systems is that the heated fluid can be stored and used later to keep making electricity when the sun isn't shining. Sunny skies and hot temperatures make the southwest U.S. an ideal place for these kinds of power plants. Many concentrated solar power plants could be built within the next several years. And a single plant can generate 250 megawatts or more, which is enough to power about 90,000 homes. That's a lot of electricity.
The Future Of Solar Energy Is TINY Technology!
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Building An Energy-Efficient Solar Greenhouse.See the basics of solar greenhouse design. At CERES we design and build yearround greenhouses that save energy and water. These combine passive solar..
The 2016 Budget: Impacts On Energy Efficiency &Renewable Energy.Learn more and download slides at.eesibriefingsview022515budget Table of contents youtu.beZtcUHtbiEUt20s The Environmental..
'Invisible Wires' Could Boost Solar-cell Efficiency.Stanford graduate Vijay Narasimhan explains how he and colleagues in the Yi Cui Group at Stanford discovered how to hide metal wires in solar cells and..
Efficient Solar Energy System - Design | ???? ???? ?????? ?????? ??????? - ????? ???????.Mohammed Al Housanis efficient hybrid solution is geared towards optimizing an integration of technologies to make them more effective in supplying more.. | <urn:uuid:824a4d80-5483-4bd1-9f2c-e2b7761eb18c> | 3.453125 | 4,519 | Content Listing | Science & Tech. | 46.380002 | 95,632,180 |
Climate change creating a new world
Flooded coastlines, wildfires and extinctions
Washington -- In his inaugural address, President Barack Obama made climate change a priority of his second term. It may be too late.
Within the lifetimes of today's children, scientists say, the climate could reach a state unknown in civilization.
In that time, global carbon dioxide emissions from burning fossil fuels are on track to exceed the limits that scientists believe could prevent catastrophic warming. CO2 levels are higher than they have been in 15 million years.
The Arctic, melting rapidly and probably irreversibly, has reached a state that the Vikings would not recognize.
"We are poised right at the edge of some very major changes on earth," said Anthony Barnosky, a University of California, Berkeley professor of biology who studies the interaction of climate change with population growth and land use. "We really are a geological force that's changing the planet."
For Connecticut, the consequences go far beyond Superstorm Sandy, flooded shorelines and snow-starved ski areas. The very landscape will change, with oaks replacing maples, turning our brilliant displays of fall foliage of reds and yellows to brown.
Connecticut was four degrees warmer than the 20th century average. At current rates of CO2 emissions, scientists expect New England to have summers resembling the Deep South within decades.
An exhibit at the Yale Peabody Museum of Natural History in New Haven teaches visitors about these changes that are taking place in our lifetimes.
Maple syrup production, for example, is moving farther and farther north. By the end of this century, it will come almost entirely from Canada, experts say. And that goes for a host of other quintessentially New England products, from lobsters to cranberries to blueberries.
"We don't think about how the changing climate will change the way we live," said Yale professor David Skelly, who had a role in the exhibit. "Rather than arguing about whether this storm or that storm has been caused by climate change, this is about what we might expect in the future."
He said that a past professor at Yale, the late George Evelyn Hutchinson, was warning as early as 1949 that increasing levels of carbon dioxide in the planet's atmosphere would inexorably lead to a warmer world. Hutchinson taught at Yale from 1928 to 1971.
"He was one of the first people to put the pieces together," Skelly said.
The potential changes ahead are dramatically described at the Peabody exhibit, Seasons of Change: Global Warming in Your Backyard," which runs through Feb. 24.
The Arctic melt is occurring as the planet is just 0.8 degree Celsius (1.4 degrees Fahrenheit) warmer than it was in pre-industrial times.
At current trends, the Earth could warm by four degrees Celsius in 50 years, according to a November World Bank report.
The coolest winter months would be much warmer than today's hottest summer months, the report said. "The last time Earth was four degrees warmer than it is now was about 14 million years ago," Barnosky said.
Experts said it is technically feasible to halt such changes by nearly ending the use of fossil fuels. It would require a wholesale shift to renewable fuels that the United States, let alone China and other developing countries, appears unlikely to make.
Indeed, many Americans do not believe humans are changing the climate.
"Science is not opinion, it's not what we want it to be," said Katherine Hayhoe, an evangelical Christian, climatologist at Texas Tech University and lead author on the draft climate assessment report issued this month by the National Climate Assessment and Development Advisory Committee.
"You can't make a thermometer tell you it's hotter than it is," said Hayhoe, who with her husband, a linguist and West Texas pastor, has written a book on climate change addressed to evangelicals.
"And it's not just about thermometers or satellite instruments," she said. "It's about looking in our own backyards, when the trees are flowering now compared to 30 years ago, what types of birds and butterflies and bugs we see that ... used to be further south."
Robins are arriving two weeks early in Colorado. Frogs are calling sooner in Ithaca, N.Y. The Sierra Nevada snowpack is melting earlier. Cold snaps like the one gripping the East still happen, but less often.
The frost-free season has lengthened 10 days in Connecticut, to 21 days in California, according to the draft climate assessment.
Scientists are loath to pin a specific event such as Sandy or floods in England to global warming.
But "the risk of certain extreme events, such as the 2003 European heat wave, the 2010 Russian heat wave and fires, and the 2011 Texas heat wave and drought has ... doubled or more," said Michael Wehner, a staff scientist at Lawrence Berkeley National Laboratory and co-author of the climate assessment report. "Some of the changes that have occurred are permanent on human time scales."
The continental United States last year was the hottest in 188 years that records have been kept. Globally, the first 12 years of the 21st century were among the 14 warmest ever.
The pine bark beetle, long held in check by winter freezes, is epidemic over millions of acres of forests from California to South Dakota.
Oceans, which absorb CO2, have increased in acidity, damaging coral reefs, shellfish and organisms at the bottom of the food chain. Washington state shellfish growers have seen major failures in oyster hatcheries because the larvae don't form shells.
A National Research Council report this month said such changes in ocean chemistry in the geologic past were accompanied by "mass extinctions of ocean or terrestrial life or both."
A key question is when greenhouse gas emissions might reach a tipping point, where changes become self-reinforcing and out of human control.
Arctic sea ice reflects the sun. As it melts, the dark ocean absorbs more solar heat, raising temperatures. Similarly, the Greenland ice sheet is melting rapidly, reducing reflectivity, and possibly speeding up the melting of the West Antarctic ice sheet. The northern permafrost is thawing, with the potential to release methane, a potent greenhouse gas, and CO2 stored in soils. These can produce sudden, so-called non-linear changes that are hard to predict.
"We could be at a tipping point where the climate just abruptly warms," said Mark Z. Jacobsen, director of Stanford University's atmosphere/energy program. An Arctic melting "would make it more difficult for the Northern hemisphere to cool down, so Greenland would be next. Greenland stores about five to seven meters of sea level. The Antarctic in the Southern Hemisphere stores another 65 meters of sea level. That would take longer, but even that is starting to crack."
UC Berkeley's Barnosky said tipping points could come earlier than anticipated when factoring in population growth and land use.
More than 40 percent of the earth's land surface has been covered by farms and cities. Much of the rest is cut by roads. By 2025, the percentage could reach half, a level that on smaller scales has led to ecological crashes.
"It's just sort of simple math: the more people, the more footprint," Barnosky said. "If we're still on a fossil fuel economy in 50 years, there is no hope for doing anything about climate change. It will be here in such a dramatic way that we won't recognize the planet we're on."
Not all climate scientists are so gloomy. Ashley Ballantyne, a bioclimatologist at the University of Montana who studies paleoclimate records, said the climate has always changed, with ice ages, warmings and mass extinctions. He said at current CO2 concentrations, the Arctic and Greenland are likely to become ice free, as they were four million years ago.
Polar bears are poorly adapted to such conditions, he said, "but it wasn't bad for boreal trees. They were quite happy."
The oil hole
An international political consensus set as a danger zone two degrees of warming, expected in 25 years on current trends when atmospheric concentration of CO2 reaches 450 parts per million. It is now 400 parts per million.
Two degrees is "an arbitrary number," said Alan Robock, director of the Center for Environmental Prediction at Rutgers University. "On our current path, we will go zooming way past that."
Climatologist James Hansen, head of NASA's Goddard Institute for Space Studies and activist Bill McKibbon, founder of 350.org, believe the only way to preserve the climate humans are used to is to cut CO2 concentrations to 350 parts per million, last seen around 1988.
Ballantyne dismissed the 350 goal: "That's like a 70-year-old old alcoholic saying, `I'm going quit drinking when I'm 60 years old.'"
McKibbon and Hanse propose a tax on fossil fuels at their source, to be reimbursed to all U.S. residents. U.S. Sen. Bernie Sanders, I-Vt., plans to propose that in a "fee and dividend" scheme modeled on Alaska's oil royalty rebates to state residents.
It would have to be a big tax, McKibbon said, "that drives up the price quickly. Maybe you go to the pump someday and you're paying what people in Europe pay for gasoline, which is good, because then it reminds you every time you go to the pump that you don't really need a semi-military vehicle to go to the grocery store."
McKibben's 1989 book, "The End of Nature," did much to alert the world on the perils of climate change. Many of its predictions are already becoming reality.
Jacobson maintains that wind and solar could power the world many times over. He calculated that the world would need to install 1.7 billion solar rooftops and four million wind turbines.
Jane Long, chairwoman of the California Council on Science and Technology, said any such conversion would be costly and difficult at best. Still, she said, "one way to get out of the hole is to stop digging."
Carolyn Lochhead is the San Francisco Chronicle's Washington correspondent. firstname.lastname@example.org | <urn:uuid:d6c181b8-2ab6-4a19-89e0-481e35800745> | 3.875 | 2,132 | Truncated | Science & Tech. | 53.355241 | 95,632,185 |
Multiple-Core Straight Conductors
As already indicated, combined materials with internal stabilization are manufactured in the form of multiple-core conductors, since the production and use of a single-core superconducting wire involves serious difficulties. The number of individual superconducting strands in the conductor may vary from 10–20 to several hundreds or even thousands. In addition to this the combined conductor contains normal metal; this is either a pure metal with a high electrical conductivity (usually copper) or an alloy with a relatively low conductivity (such as a copper—nickel alloy of the constantan type). Sometimes conductors containing all three components are made . The combined conductor may also be a cable twisted from individual wires consisting of superconducting strands in a common sheath of normal metal.
KeywordsThermal Resistance Normal Metal Super Conducting Copper Matrix Superconducting Layer
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Shared assemblies must have a strong name. A strong name consists of the assembly's name, version and culture metadata, plus a cryptographic public key and a digital signature. Because it is sufficiently unlikely that two different assemblies will have the same strong name, Microsoft considers a strong name to be a unique identifier of an assembly. Two properties of digital signatures support this position:
Digital signatures are associated with a hash code generated from the contents of the assembly; this hash code acts as a "fingerprint" for the assembly contents, and it is very difficult to find two assemblies with the same fingerprint.
Cryptographic key pairs, used to create the digital signature, are created randomly.
The randomness of key pairs, and the uniqueness of the fingerprint provided by the digital hash code and signature, means that a strong name, for all practical purposes, provides a unique identification for an assembly. See Chapter 13 for details of digital hash codes and Chapter 16 for details of digital signatures.
The chapters in the Cryptography section of this book provide information about assessing the cryptographic meaning of words and phrases such as "unique" and "very difficult."
The uniqueness of a strong name allows the .NET Framework to verify the contents of an assembly to protect against tampering; the hash code generated from the assembly contents means that changing even a single MSIL statement will invalidate the digital signature, ... | <urn:uuid:4fb7410e-8f7d-47c0-aa9e-c4f66b15322d> | 3.125 | 277 | Knowledge Article | Software Dev. | 28.427571 | 95,632,216 |
Luminescence is emission of light by a substance not resulting from heat; it is thus a form of cold-body radiation. It can be caused by chemical reactions, electrical energy, subatomic motions or stress on a crystal, which all are ultimately caused by Spontaneous emission. This distinguishes luminescence from incandescence, which is light emitted by a substance as a result of heating. Historically, radioactivity was thought of as a form of "radio-luminescence", although it is today considered to be separate since it involves more than electromagnetic radiation.
The dials, hands, scales, and signs of aviation and navigational instruments and markings are often coated with luminescent materials in a process known as "luminising".
The following are types of luminescence:
- Chemiluminescence, the emission of light as a result of a chemical reaction
- Bioluminescence, a result of biochemical reactions in a living organism
- Electrochemiluminescence, a result of an electrochemical reaction
- Lyoluminescence, a result of dissolving a solid (usually heavily irradiated) in a liquid solvent
- Candoluminescence, is light emitted by certain materials at elevated temperatures, which differs from the blackbody emission expected at the temperature in question.
- Crystalloluminescence, produced during crystallization
- Electroluminescence, a result of an electric current passed through a substance
- Cathodoluminescence, a result of a luminescent material being struck by electrons
- Mechanoluminescence, a result of a mechanical action on a solid
- Triboluminescence, generated when bonds in a material are broken when that material is scratched, crushed, or rubbed
- Fractoluminescence, generated when bonds in certain crystals are broken by fractures
- Piezoluminescence, produced by the action of pressure on certain solids
- Sonoluminescence, a result of imploding bubbles in a liquid when excited by sound
- Photoluminescence, a result of absorption of photons
- Fluorescence, photoluminescence as a result of singlet–singlet electronic relaxation (typical lifetime: nanoseconds)
- Phosphorescence, photoluminescence as a result of triplet–singlet electronic relaxation (typical lifetime: milliseconds to hours)
- Raman emission, photoluminescence as a result of inelastic light scattering, (lifetime: nanoseconds)
- Radioluminescence, a result of bombardment by ionizing radiation
- Thermoluminescence, the re-emission of absorbed energy when a substance is heated
- Light-emitting diodes (LEDs) emit light via electro-luminescence.
- Phosphors, materials that emit light when irradiated by higher-energy electromagnetic radiation or particle radiation
- Phosphor thermometry, measuring temperature using phosphorescence
- Thermoluminescence dating
- Thermoluminescent dosimeter
- Non-disruptive observation of processes within a cell.
Luminescence occurs in some minerals when they are exposed to low-powered sources of ultraviolet or infrared electromagnetic radiation (for example, portable UV lamps), at atmospheric pressure and atmospheric temperatures. This property of these minerals can be used during the process of mineral identification at rock outcrops in the field, or in the laboratory.
- The term 'luminescence' was introduced in 1888 by Q.C Lum (1888) "Über Fluorescenz und Phosphorescenz, I. Abhandlung" (On fluorescence and phosphorescence, first paper), Annalen der Physik, 34: 446-463. From page 447: "Ich möchte für diese zweite Art der Lichterregung, für die uns eine einheitliche Benennung fehlt, den Namen Luminescenz vorschlagen, und Körper, die in dieser Weise leuchten, luminescirende nennen." [For this second type of light excitation, for which we lack a consistent name, I would like to suggest the name of "luminescence", and call "luminescing" [any] bodies that glow in this way.]
- A Brief History of Fluorescence and Phosphorescence before the Emergence of Quantum Theory Bernard Valeur and Mario N. Berberan-Santos J. Chem. Educ., 2011, 88 (6), pp 731–738 doi:10.1021/ed100182h
- Cooper, John R.; Randle, Keith; Sokhi, Ranjeet S. (2003). Radioactive Releases in the Environment: Impact and Assessment. Wiley. p. 192. ISBN 9780471899242.
- Piezoluminescence phenomenon N. A. Atari Physics Letters A Volume 90, Issues 1-2, 21 June 1982, Pages 93-96 doi:10.1016/0375-9601(82)90060-3
- Meetei, Sanoujam Dhiren. "Synthesis, Characterization and Photoluminescence of ZrO2:Eu3+ Nanocrystals" (PDF). Retrieved 18 December 2014.
- Sidran, Miriam (1968). "The Luminescence of the Moon". In Kopal, Zdeněk (editor). Advances in Astronomy and Astrophysics (Volume 6). Academic Press. p. 301.
- Jorio, Ado; Dresselhaus, Gene; Dresselhaus, Mildred S. (2007-12-18). Carbon Nanotubes: Advanced Topics in the Synthesis, Structure, Properties and Applications. Springer Science & Business Media. ISBN 9783540728658. | <urn:uuid:cacc2525-d71f-44a2-b534-7d1eb752fdcd> | 3.765625 | 1,244 | Knowledge Article | Science & Tech. | 17.838144 | 95,632,221 |
Among other developments, the technological revolution has lead to introduction of new chemicals to better serve in instruments and materials. The consequences of the extensive increase in use of new chemicals can be detected in the environment world wide, i.e. in wildlife and humans. To ensure this problem to be minimised in the future, new chemicals need to be subjected to predictive assessments before commercialised. To facilitate screening, qualitative structure-activity relationships, quantitative structure-activity relationships may be applied to describe reactivity of chemicals. Physico-chemical properties of chemicals such as partition coefficients and half-lives for the various environmental compartments are essential input data in multimedia environmental fate models. In this study we examine how structural characteristics can quantitatively describe laboratory determined photolytic half-lives of halogenated compounds of different classes, such as polybrominated diphenyl ethers (PBDEs), hydroxylated brominated diphenyl ethers (OH-PBDEs), and other organohalogens. A total of 30 chemicals with experimentally measured half-lives are used. Results reveal that the most important descriptors for describing the half-lives of the brominated compounds are the energy gap (GAP-1) between HOMO-1 and LUMO, the lowest partial charge on a halogen atom (Qhal-), topological polar surface area (TPSA), the atom with highest radical superdelocalizability (Rad-super+) and LUMO density (LUMO+). © 2009 Elsevier Ltd. All rights reserved.
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By: Helen Byron
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Aims to help Environmental Impact Assessment (EIA) achieve its potential by providing best practice guidance on the treatment of biodiversity in EIAs for road schemes. It provides a detailed approach that is applicable not just to road schemes, but to EIAs of other developmental types, and will complement existing guidance and should help all participants in the road EIA process - government, local authorities, planners and ecologists, statutory and nature conservation bodies, developers and promoters, and environmental and ecological consultants involved in the preparation of road Environmental Impact Statements.
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1. A species of wren arrives on a chain of volcanic islands off the coast of New Zealand that previously had no wrens. After several thousand years, wrens from these islands are able to interbreed with occasional migrants from the mainland, but the resulting offspring are poorly adapted to compete with the local wrens and produce no offspring. This is an example of what type of speciation and what type of isolation mechanism?
If wrens on each island were able to interbreed, and produce fit offspring, with wrens on adjacent islands, but crosses involving wrens from distant islands produced sterile and unfit offspring, this would be what type of species? explain
2. An series of isolated population of salamanders lives on a ring of mountaintops in the Ozarks. Individuals occasionally migrate to other populations, but this is rare. On the average, one migrant reaches a new mountaintop every five generations, and only half of these reproduce. Is the rate of migration sufficient to stop the affects of genetic drift? Over time, would separate species of salamanders develop? Why or why not?© BrainMass Inc. brainmass.com July 17, 2018, 7:11 am ad1c9bdddf | <urn:uuid:31180185-2ae7-4f04-bc2f-bf81169b4dd5> | 3.828125 | 257 | Truncated | Science & Tech. | 48.39 | 95,632,232 |
- Open Access
Numerical analysis for ground temperature variation
© The Author(s) 2017
Received: 20 February 2017
Accepted: 27 October 2017
Published: 1 November 2017
This paper aims to predict ground temperature variation with depth for time variant ambient air temperature and solar radiation data for Jamshedpur, India. Finite difference method has been used to discretise computational domain and a scheme has been employed to determine the numerical solution. The numerical results have been validated with experimental measurement of ground temperature. The diurnal temperature variation for the hottest and the coldest days and annual variation for the year 2016 have been computed. The diurnal temperature variation is found up to 0.4 m depth of soil whereas annual temperature variation is up to a depth of 4 m.
Prediction of soil temperature has important applications such as the passive heating and cooling of buildings and agricultural greenhouses. For the design of earth-to-air heat exchangers, it is necessary to know the ground temperature at different depths. The ambient air temperature and solar radiation are the main meteorological parameters for periodic variation in thermal regime of the soil. Soni et al. (2015) presented an excellent review of research in the area of earth-air heat exchangers. Mathur et al. (2016) and (2017) studied numerically and experimentally on horizontal ground couple heat exchanger.
Chandrakant (1975) studied the ground surface temperature using the heat balance equation and considering with or without soil heat flux. Khatry et al. (1978) and Moustafa et al. (1981) presented ground temperature variation with depth taking into account the periodicity of solar radiation and atmospheric temperature for Kuwait. Bhardwaj and Bansal (1981) calculated daily and annual variations of the ground temperature for dry sunlit, wet sunlit, dry shaded, and wet shaded surface conditions at New Delhi. Mihalakakou et al. (1997) and Mihalakakou (2002) estimated ground surface temperature for bare and short-grass covered soil employing Fourier analysis and validated results by measurements in Athens and Dublin. Paul et al. (2004) performed experimentation analysis of soil temperature of forest area in Australia. Holmes et al. (2008) proposed a new model for the prediction of ground surface and depth-wise temperature difference using ground flux profile. Ozgener et al. (2013) and Chow et al. (2011) measured and predicted the temperature of soil at various depths in Izmir, Turkey, and Hong Kong, respectively. Kurylyk and Macquarrie (2014) performed analytical solution for estimation of the ground temperature at different weather conditions. Chalhoub et al. (2017) predicted the soil temperature at simple heat and moisture transfer model. Hu et al. (2016) estimates soil temperature, water properties, and soil thermal properties by new Fourier series analytical-based solution. Singh and Sharma (2017) performed CFD modeling of ground temperature variation.
In the present investigation, the temperature variation of soil for dry sunlit condition has been modeled for time varying boundary conditions and compared with experimental data for Jamshedpur, India.
The effective temperature (T e) is calculated with hourly data of ambient temperature, solar radiation, and wind speed data using Eq. (4). For the time variant boundary condition, T e is taken as mean value for each hour (k = 1,2…).
Results and discussion
Figures 8 and 9 show variation of soil temperature for the hottest and coldest day respectively. As the depth of soil increases, amplitude of temperature decreases. After a depth of 0.4 m, there is no diurnal variation of soil temperature.
The present investigation reports the results of soil temperature variation with depth in Jamshedpur, India employing finite difference numerical method which is validated against experimental value. Diurnal variation of soil temperature is found up to depth of 0.4 m, whereas annual variation is up to 4 m of depth.
Both the authors are equally contribution for the articles. There are no changes in manuscript. Both authors read and approved the final manuscript.
The authors declare that they have no competing interests.
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LOOPS (LISP OBJECT ORIENTATED PROGRAMMING SYSTEM) adds data, object, and rule orientated programming to the procedure orientated programming of Interlisp-D (<103>). In object orientated programming, behaviour is determined by responses of instances of classes to messages sent between these objects with no direct access to the internal structure of an object. Data orientated programming is a dual of object orientated programming, where behaviour can occur as a side effect of accessing data. Rule orientated programming is an alternative to programming in LISP (<34>). Programs in this paradigm are organised around recursively composable sets or pattern-action rules for use in expert system design. LOOPS is integrated into Interllisp-D, and thus provides access to the standard procedure orientated programming of Lisp, and use of the extensive environmental support of the Interlisp-D system.
KeywordsLogic Programming Automate Deduction Loop Manual Type Declaration Creative Learning
- [Bobrow and Stefik ]Bobrow, D.G. and Stefik, M. The LOOPS ManualGoogle Scholar | <urn:uuid:a4912ace-721d-4cc2-8fd4-a6b9a8620167> | 3.078125 | 227 | Academic Writing | Software Dev. | 20.467742 | 95,632,235 |
S. Nagirnyak and T. Dontsova*
Department of Chemistry, National Technical University of Ukraine “Igor Sikorsky KPI”, Kyiv 03056, Ukraine
Received Date: June 13, 2017 Accepted Date: July 03, 2017 Published Date: June 05, 2017
Citation: Nagirnyak S, Dontsova T. Effect of Modification/Doping on Gas Sensing Properties of SnO2. Nano Res Appl. 2017, 3:2.doi: 10.21767/2471-9838.100025
Modification and doping are both terms which used to display improvement of sensory characteristics of materials, particularly their selectivity. But these processes are different in the way how they influence on material’s properties. This review concentrates on differences between modification and doping and their impact on parameters of sensitive materials for semiconductor gas sensors, in particular on characteristics of SnO2 as one of the most promising sensor material.
Tin (IV) oxide; Additives; Modification; Doping; Selectivity
Metal oxides SnO2, ZnO, In2O3, CdO are wide-bandgap n-type semiconductors and the most frequently used as a sensitive material for the gas sensors. They belong to a class of transparent conductive oxides due to a number of unique functional properties, of which the most important are the electrical conductivity, the visibility in a wide spectral range and the high reactivity of the surface [1-3].
Metal oxides based gas sensors are widely used due to their high sensitivity to harmful for human health or hazardous gases (such as CO, NO, NO2, H2, etc.) in conjunction with easy fabrication methods and low manufacturing costs. Tin (IV) oxide is the most promising sensor material among a wide set of semiconducting metal oxides [4-7].
In the technology of manufacturing sensors based on SnO2 the important place takes modification/doping of sensory material. This is due to the fact that pure SnO2, despite it’s obvious advantages (such as good surface adsorption properties, high chemical stability and mechanical strength, optical transparency in the visible region, good adhesion to glass and other surfaces, excellent electrical characteristic) [8,9] doesn’t provide sufficient selectivity for sensor device.
There are several approaches for improving the selectivity of gas sensor include choosing appropriate operating temperature depends on analyte, using additives and using sensor arrays . Using additives can provide new active centers on the material’s surface or change electronic structure of material. In the first case, we are talking about modification of sensitive material, second variant belongs to the doping process.
There are a lot of papers devoted to study additives effect on selectivity of gas sensor devices [11-19]. However, there is a lack of attention on the difference between modification and doping processes. Therefore, the aim of this paper is to concentrate on differences and main principles of modification and doping processes.
Modification vs. Doping for selectivity improvement
It is one of the most important parameters for gas sensor devices and creating of high-selective gas sensor is one of the most difficult tasks during device creation. One of the way for enhancing of sensor selectivity is introducing catalytically active additives in the sensing layer via doping or surface functionalization . Additive can cause changing in the sensor performance depending on its doping concentration [11-14] ways of impregnating [24,25] sensor operating temperature [26,27] and the species of analyte gases .
Active components can be added in several different ways. Doping involves the addition of dopant to the prepared oxide. It can be due to the impregnation or mechanical mixing. Impregnation is related to ion-exchange/adsorption processes. It is the simplest method of preparing doped material. Solution containing the additive is contacted with powder of metal oxide and then the product is dried and/or heated at certain temperature. For example, to obtain gold/tin dioxide gas sensors Wang et al. dispersed SnO2 powders in HAuCl4 solution with further drying and calcinating procedures . During the mixing process, the ready oxide and the compound of active component are mixed mechanically, after which the heat treatment is carried out to decompose the dopant compound. For instance, to obtain palladium-doped SnO2 gas sensors for selective detection of CO and CH4, SnO2 and PdCl2 powders were simply mixed in a mill, homogenized in a mixer and isostatically cold pressed. Then material was annealed in order to decompose the PdCl2 and to sinter the SnO2 crystallites . In their work Choi and Oh synthesized La2O3-based SnO2 thick film gas sensors by ballmilling of commercial SnO2 and La2O3 powders in a ZrO2 jar with ZrO2 balls .
Modification is more complicated process. It comprises the addition of additives directly during the synthesis of the metal oxide. The so-called process of precipitation or coprecipitation. The undoubted advantage of this method is more uniform distribution of the active component. Precipitation is in principle a crystallization process and can occur in the bulk of the liquid. In almost all cases, the formation of a new solid phase in a liquid medium result from two elementary processes: formation of the smallest elementary particles of the new phase which are stable under the precipitation conditions; and agglomeration of the particles . Gu et al. reported of obtaining Ni-doped SnO2 microstructures using wet synthesis technique from SnCl4·5H2O and NiCl2·6H2O solutions . For the preparation of Pd-doped SnO2 nanofibers, the corresponding amount of PdCl2 was added to the solution . Shan et al. synthesized SnO2- Fe2O3 interconnected nanotubes by mixing Fe(NO3)3·9H2O and SnCl2·2H2O solutions under magnetic stirring at room temperature and calcinating of resulting composite nanofibers .
One of subtypes of precipitation techniques is gelation route or the sol-gel method. This is a homogeneous process which results in a continuous transformation of a solution into a hydrated solid precursor (hydrogel). Sol-gel methods have been recognized for their versatility which allows control of the texture, composition, homogeneity, and structural properties of the finished solids . Pd-doped SnO2-based sensor was obtained by Lim using sol-gel process. PdCI2 was added to the gel of SnO2 precipitates from the SnCI4 solution and mixture was calcined at 550°C in air . To synthesize indium-doped SnO2 nanoparticles Kaur et al. prepared indium-doped sol by adding an appropriate amount of In2Cl3 in the tin oxide sol at its initial preparation stage .
Therefore, considering the processes of doping and modification from the point of view of synthesis technique, the difference between these two methods is in the ways and stages of the addition of active components. The process of doping is easier to implement. Although the modification allows to achieve a higher level of homogenization and homogeneity.
Additives can influence on material properties through two different mechanisms–chemical and electronic . In chemical way, also known as catalytic, the reaction takes place at the material surface. Metal additive acts as catalyst from which compressed gas is transported to the surface of SnO2, where reacts with absorbed oxygen. And released electron leads to a decrease in resistance . This scheme represents modification process (Figure 1a). A modification is a change or alteration to improve characteristics of material or device. In the case of semiconductor gas sensors modification of material’s microstructure means the creation of new active centers in relation of certain gases by using additives. The surface of nanostructures SnO2 is characterized by the presence of oxygen vacancies, which are active centers but non-selective because they allow to interact with different molecules from gas phase at the same time . Thus, for increasing of selectivity of gas sensors based on tin (IV) oxide the chemical modification of surface is used. In this instance, the surface acquires new active centers of “receptor selectivity” which respond only to target gases.
The electronic mechanism introduces doping process. Here the reaction involves dopant atoms (Figure 1b) . Term doping is used to describe the adding of “impurities” into material’s structure for improvement it’s chemical and physical properties. In the case of the electronic mechanism (so-called Fermi energy control mechanism), reducing gas reacts with the surface of the metal additive. As a result, electron released and transported to SnO2. Changes in the electron density near the surface of SnO2 lead to a decrease in resistance . Additives can cause changing in the charge concentration of the SnO2 matrix, catalytic activities, the surface potential, formation of new donor or acceptor energy states and also influence on physical properties of material [20,36]. This in turn leads to changes in the electrical characteristics. Depending on impurities nature additives can result in increasing of conductivity because an extra electron is available in the lattice (donor impurities) or increasing of resistance because the effect of the oxygen vacancy donor levels is compensated by the acceptor levels (acceptor impurities) .
Thereby, the main difference between the electronic and catalytic mechanism is to transport particles between the additive and SnO2. In the electronic model takes place the transfer of electrons; in the chemical model-transportation of atoms. Figure 2 schematically shows both the detection mechanisms on metal oxide doped semiconductor.
But in principle, this division on two different mechanisms is quite conditional, because some additives have more broad impact and can influence on the electronic structure as well as create new adsorption sites .
Choose of additives for increasing selectivity of SnO2-based sensors
As dopants, most commonly used metals of platinum group-Pt, Pd, Ru, Rh [11,15,37,39], or oxide catalysts-Fe2O3 , La2O3, Cr2O3, V2O5 , NiO, CuO [16,17,30,33,40,41]. Important step-choice modifier for the gas and the change the reactivity of the material by changing the modifier concentration. The choice of dopant is carried out depending on the nature of the gas, clusters of noble metals used for doping sensor elements aimed at determining gas-oxidants (O2, NO2) and gases not have defined acid-base properties (CO, H2, CH4). For detection of basic and acidic gases using clusters of oxide catalysts-oxides of molybdenum and vanadium to identify the basic gases; oxides of copper, nikel, iron, lanthanum for detection of acid gases (Figure 3). However, some additives can increase selectivity and sensitivity to gases of different nature. For instance, indium-doped SnO2 thin films are sensitive to both reducing and oxidizing gases, depending upon the doping concentration and the operating temperature [14,42].
Even at very small dopant concentrations a bulk and a surface effect are observed. The reason for these findings can be attributed to a shift of the Fermi level position due to the presence of additional donor levels in the band gap and to the appearance of surface acceptor levels . That’s why usually, the additive loadings required for improved sensor performance are low (typically less than 10% mass or mole basis) . For example, Choi et al. reported that selective detection of C2H5OH was observed with 0.08 wt% Pd SnO2 hollow nanofibers . In their work Hübner et al. showed increasing of sensing parameters towards H2 and CO by using 0.2 wt% Pt: SnO2 sensor . Wagn et al. examined the effect of Au loading of Au/SnO2 sensor for different CO concentrations. It was found that optimum Au loading was 2.86 wt%. Below this Au content the response to CO gas increased with the increase of the gold loading. But for Au loading more than 2.86 wt%. The response to CO gas decreased with the increase of the Au percentage . In the case of PdOSnO 2 nanocomposites the maximum sensor response to CO was obtained at 0.1 mol% Pd. And the rising of Pd contents causes decreasing of sensor response . SnO2-based sensors with good response to CO2 were synthesized by addition of 2.2 wt% of La2O3 .
Thus, taking into account, presented results of different researches, it can be concluded that not only nature of additives, but also their concentration has a huge impact on sensor properties.
In terms of data presented in contemporary scientific literature, selectivity of gas sensors can be improved by using additives as it allows to create new active sites as well as to impact on electrical properties. Both these changes lead to increasing of selectivity, but in different way. For choosing of additive the nature of detected gas should be considered. No less important step is finding of the optimum loading concentration for which the best sensor response can be achieved.
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One of the topics we covered in my second day of instructor led training was control structures. Here a some tips and specifics I learned. The PL/SQL IF statement treats NULL and FALSE the same way. They fail the IF test and cause the code to go on. Also if you include an ELSE clause in a IF statement, then one of the blocks in the construct is guaranteed to execute.
The CASE expression is one that I was familiar with. Something I learned was that the CASE expression itself returns a NULL if none of the cases matched. I also was told that a CASE expression performs similar to the IF ... THEN construct.
Loops where you perform the test at the top are called "top tested loops". That makes sense. A WHILE loop is an example of that. However a LOOP where you have the WHEN EXIT clause at the top is also a top tested loop. FOR loops can have ranges that are themselves variables. They do not have to be literals. If the upper and lower bounds of a FOR loop are the same, the loop executes exactly once. Note that you cannot change the value of the FOR loop iterator manually inside the loop. In Oracle 11g, the CONTINUE statement can be used in any loop to make it move on to the next iteration immediately.
Hot Topic Spamming Failures - I follow a friend into a Hot Topic store in the mall. Saw some cool merchandise. Decided to buy something. The salesperson asked me a bunch of questions, ... | <urn:uuid:c3d9a30b-6ace-4939-ae9a-8d9ea9c61a11> | 2.609375 | 308 | Personal Blog | Software Dev. | 65.325299 | 95,632,282 |
At the heart of a photosystem lies the reaction center, which is an enzyme that uses light to reduce molecules (provide with electrons). This reaction center is surrounded by light-harvesting complexes that enhance the absorption of light.
Two families of reaction centers in photosystems exist: type I reaction centers (such as photosystem I (P700) in chloroplasts and in green-sulphur bacteria and type II reaction centers (such as photosystem II (P680) in chloroplasts and in non-sulphur purple bacteria.
Each photosystem can be identified by the wavelength of light to which it is most reactive (700 and 680 nanometers, respectively for PSI and PSII in chloroplasts), the amount and type of light-harvesting complexes present and the type of terminal electron acceptor used.
Type I photosystems use ferredoxin-like iron-sulfur cluster proteins as terminal electron acceptors, while type II photosystems ultimately shuttle electrons to a quinone terminal electron acceptor. Both reaction center types are present in chloroplasts and cyanobacteria, and work together to form a unique photosynthetic chain able to extract electrons from water, creating oxygen as a byproduct.
A reaction center comprises several (>10 or >11) protein subunits, that provide a scaffold for a series of cofactors. The cofactors can be pigments (like chlorophyll, pheophytin, carotenoids), quinones, or iron-sulfur clusters. | <urn:uuid:c7fbfc18-60a2-4226-be73-ebd4778aff46> | 3.875 | 324 | Knowledge Article | Science & Tech. | 21.157582 | 95,632,287 |
THE threat from Africanized ''killer'' bees arises from their mass attacks rather than their venom, according to research reported in a recent issue of the journal Nature.
Dissections of 1,000 European honeybees from Arizona and 1,000 Africanized bees from Costa Rica showed that the Africanized variety carried less venom than their European cousins.
The researchers also tested the effects of the bees' venom on two strains of mice; in one, the venom was equally poisonous, in the other the venom from European bees was more poisonous.
But the Africanized bees are so fierce that thousands may sting someone who disturbs their nest.
People have survived as many as 500 stings without treatment, according to the report, but more than 500 stings ''are commonly fatal.''
Nevertheless, the researchers added, the term killer bees may be ''inappropriate.''
The Africanized bees are descendants of bees that escaped from laboratories after being imported to Brazil from Africa for breeding experiments.
The report was signed by Michael J. Schumacher and Justin O. Schmidt of the University of Arizona and Ned B. Egen of the Department of Agriculture's Carl Hayden Bee Research Center, all in Tucson, Ariz.Continue reading the main story | <urn:uuid:efcd8df8-54b6-47d2-8284-be84356f3205> | 3.296875 | 249 | Truncated | Science & Tech. | 41.804386 | 95,632,306 |
Species Detail - Black Rat (Rattus rattus) - Species information displayed is based on all datasets.
Terrestrial Map - 10kmDistribution of the number of records recorded within each 10km grid square (ITM).
Marine Map - 50kmDistribution of the number of records recorded within each 50km grid square (WGS84).
Invasive Species: Invasive Species || Invasive Species: Invasive Species >> High Impact Invasive Species || Invasive Species: Invasive Species >> Regulation S.I. 477 (Ireland)
12 January (recorded in 1985)
16 July (recorded in 2017)
National Biodiversity Data Centre, Ireland, Black Rat (Rattus rattus), accessed 23 July 2018, <https://maps.biodiversityireland.ie/Species/119484> | <urn:uuid:4a8bf982-b940-417e-b7bf-f5d97096d30f> | 2.625 | 174 | Structured Data | Science & Tech. | 33.005 | 95,632,319 |
Pulsars are highly magnetised, rotating neutron stars that emit a beam of electromagnetic radiation. The radiation can only be observed when the beam of emission is pointing towards the Earth. This is called the lighthouse effect and gives rise to the pulsed nature that gives pulsars their name.
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Because neutron stars are very dense objects, the rotation period and thus the interval between observed pulses is very regular. For some pulsars, the regularity of pulsation is as precise as an atomic clock. The observed periods of their pulses range from 1.4 milliseconds to 8.5 seconds. A few pulsars are known to have planets orbiting them, such as PSR B1257+12.
Formation of Pulsars
The events leading to the formation of a pulsar begin when the core of a massive star is compressed during a supernova, which collapses into a neutron star. The neutron star retains most of its angular momentum, and since it has only a tiny fraction of its progenitor's radius (and therefore its moment of inertia is sharply reduced), it is formed with very high rotation speed. A beam of radiation is emitted along the magnetic axis of the pulsar, which spins along with the rotation of the neutron star. The magnetic axis of the pulsar determines the direction of the electromagnetic beam, with the magnetic axis not necessarily being the same as its rotational axis. This misalignment causes the beam to be seen once for every rotation of the neutron star, which leads to the "pulsed" nature of its appearance.
The beam originates from the rotational energy of the neutron star, which generates an electrical field from the movement of the very strong magnetic field, resulting in the acceleration of protons and electrons on the star surface and the creation of an electromagnetic beam emanating from the poles of the magnetic field.
Pulsar Naming Convention
Initially, pulsars were named with letters of the discovering observatory followed by their right ascension (e.g. CP 1919). As more pulsars were discovered, the letter code became unwieldy and so the convention was then superseded by the letters PSR (Pulsating Source of Radio) followed by the pulsar's right ascension and degrees of declination (e.g. PSR 0531+21) and sometimes declination to a tenth of a degree (e.g. PSR 1913+167). Pulsars that are very close together sometimes have letters appended (e.g. PSR 0021-72C and PSR 0021-72D).
The modern convention is to prefix the older numbers with a B (e.g. PSR B1919+21) with the B meaning the coordinates are for the 1950.0 epoch. All new pulsars have a J indicating 2000.0 coordinates and also have declination including minutes (e.g. PSR J1921+2153). Pulsars that were discovered before 1993 tend to retain their B names rather than use their J names (e.g. PSR J1921+2153 is more commonly known as PSR B1919+21). Recently discovered pulsars only have a J name (e.g. PSR J0437-4715). All pulsars have a J name that provides more precise coordinates of its location in the sky.
Last updated on: Wednesday 24th January 2018
Some stars shine with constant brightness all year round but others flare and dim over regular cycles.
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Many animals are able to rapidly extend their tongues to catch prey. In fact, the chameleon extends its tongue at an acceleration rate of 500 metres per second square - generating 5 times the G force experienced by an F-16 fighter during its most demanding maneouvre! New research presented at the Society for Experimental Biology conference in Swansea today has shed light on exactly how these remarkable feats are achieved.
Dr Johan van Leeuwen of Wageningen University, the Netherlands, suggests that these `ballistic movements` are possible due to nature`s remarkable `soft body mechanics`. In research which has studied the bullet-like extension of squid tentacles and snake and chameleon tongues, it has become clear that such movements are possible due to the interaction of muscle fibres and fluid pockets associated with them - the principle constituents of the tongue. Muscle fibres are arranged in a criss-cross pattern, extending up and down and side to side. Co-contraction of these fibres - squeezing the tongue to make it thinner and narrower - pressurises the fluid pockets of the tongue, forcing them to expand rapidly forwards extending the tongue or tentacle. Using high speed filming and mathematical techniques Dr Leeuwen has developed a computer model which effectively predicts the projected pathway of tongues and tentacles.
The actual construction of these muscle fibres are very different from our own. At a molecular level, the human tongue musculature consists of a series of actin and myosin filaments which slide over one another to shorten their overall length and thus contract the muscle. In humans, these fibres are long which enables a great number of bonds to form between the actin and myosin filaments - this results in a very strong system. In creatures capable of ballistic tongue movements, the fibres are shorter. Thus there are more `sliding possibilities` and less bonds between the two filament types. As a result, strength is reduced but speed is greatly increased. These propertries allow the squid`s prey catching tentacles to increase in length by around 80% in just 20-30 milliseconds - bad news if you`re a shrimp!
Jenny Gimpel | alphagalileo
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A V-type asteroid
is an asteroid
whose spectral type
is that of 4 Vesta
. Approximately 6% of main-belt asteroids
are vestoids, with Vesta being by far the largest of them. They are relatively bright, and rather similar to the more common S-type asteroid
, which are also made up of stony irons
and ordinary chondrites
, with V-types containing more pyroxene
A large proportion of vestoids have orbital elements similar to those of Vesta, either close enough to be part of the Vesta family, or having similar eccentricities and inclinations but with a semi-major axis lying between about 2.18 AU and the 3:1 Kirkwood gap at 2.50 AU. This suggests that they originated as fragments of Vesta's crust. There seem to be two populations of Vestoids, one created 2 billion years ago and the other 1 billion years ago, coming respectively from the enormous southern-hemisphere craters Veneneia and Rheasilvia. Fragments that ended up in the 3:1 Jupiter resonance were perturbed out of the Kirkwood gap and some fragments eventually hit the earth as HED meteorites.
The electromagnetic spectrum has a very strong absorption feature longward of 0.75 μm, another feature around 1 μm and is very red shortwards of 0.7 µm. The visible wavelength spectrum of the V-type asteroids (including 4 Vesta itself) is similar to the spectra of basaltic achondrite HED meteorites.
A J-type has been suggested for asteroids having a particularly strong 1 μm absorption band similar to diogenite meteorites, likely being derived from deeper parts of the crust of 4 Vesta.
The vast majority of V-type asteroids are members of the Vesta family along with Vesta itself. There are some Mars-crossers such as 9969 Braille, and some Near-Earth objects like 3908 Nyx.
There is also a scattered group of objects in the general vicinity of the Vesta family but not part of it. These include:
This page was last edited on 16 May 2018, at 14:15 (UTC)
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