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The larch casebearer Coleophora laricella (Hbn.) is now established throughout all western larch stands in Region 1. Population levels have begun to fluctuate in some of the older infested stands; however, it is still on the increase in more recently invaded territory. During the past 2 years work was begun to develop a method to forecast defoliation and tg ollow trends of the larch casebearer (Ciesla and Bousfield 1971).111/ The purpose of these evaluations was to establish the relationship between the overwintering population and subsequent defoliation for prediction purposes.
This work has no parents.
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posted by alice
The meter stick in the drawing can rotate about an axis located at the 20.0-cm mark. The axis is perpendicular to the screen. A force F acts at the left end; the force is perpendicular to the meter stick and has a magnitude of 175 N. A second force, either F1 or F2, acts at the 80.0-cm mark, as the drawing shows. The meter stick is in equilibrium. Which force, F1 or F2, acts on the meter stick, and what is its magnitude? | <urn:uuid:e51db16a-7730-486b-8115-a7f8f073467a> | 3.578125 | 113 | Q&A Forum | Science & Tech. | 86.37625 | 95,644,390 |
Name the four families of hydrocarbons.
2. Hexyne is a hydrocarbon containing _____ carbons and a __________ bond.
3. Cyclobutene is a hydrocarbon containing _____ carbons, a ______ and a ______ bond.
4. Alcohols contain an ________ group.
5. A compound containing 5 carbons and a fluorine would be named _______________.
6. Amines and amides both contain the element _______________
7. The reaction shown below is a ____________________ type reaction.
CH3CH3 + Br2 -----> CH3CH2Br + HBr
8. The reaction shown below is a ____________________ type reaction.
CH2=CH2 + H2 -----> CH3CH3
9. Name the four main classes of biochemicals.
10. Blood sugar is a sugar chemically known as _______________
11. The carbohydrate found in bread which serves as a source of glucose is called
____________ and is a member of the family of sugars called _____________
because it contains many monosaccharide molecules.
12. There are _____ different amino acids which are the monomer molecules used to
construct the polymer molecules called ________________ from which all muscle
tissue is made.
13. There are approximately _______________ different proteins in the human body.
14. Name four classes of lipids.
15. The two kinds of nucleic acids are __________ and __________
16. Name the two types of nuclear reactions.
The three types of simpler materials produced by radioactivity nuclear fission reactions are
_______________, ________________ and _______________
18. The time required for one-half of the atoms of a radioactive nuclei sample to decay is called
the _______________ of the nuclei.
19. The type of nuclear reaction shown below is __________ and the nuclear symbol
of the missing material is
27Al13 + ? → 30P15 + 1n0
sorry need these 3 things too. to amke sure they are all right.
2. BALANCE THE FOLLOWING EQUATIONS:
Al(OH)3 + HNO3 → Al(NO3)3 + H2O
LiAl(OH)4 + H2O → LiOH + Al(OH)3 + H2O
Ca + H3PO4 → Ca3(PO4)2 + H2© BrainMass Inc. brainmass.com July 22, 2018, 10:25 pm ad1c9bdddf
This solution comprised of some important fill in the blank questions related to basic chemistry. | <urn:uuid:29fb6dcc-9fc5-44a9-b87a-49e7875874a6> | 3.90625 | 558 | Q&A Forum | Science & Tech. | 80.240599 | 95,644,403 |
Dispersion of dissolved or suspended materials in flowing streams / by Robert E. Glover; prepared in cooperation with the U.S. Atomic Energy Commission.
- Physical Description: 1 online resource (iii, B32 pages) : illustrations.
- Publisher: Washington : United States Department of the Interior, Geological Survey, 1964.
"Transport of radionuclides by streams."
|Bibliography, etc. Note:||
Includes bibliographical references (pages B31-B32).
|Source of Description Note:||
Description based on online resource; title from PDF title page (USGS viewed July 20, 2017).
Search for related items by subject
Rivers > United States.
Radioactive waste disposal.
Radioactive pollution of water.
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Built: about 1 month ago
Size: 147 KB
Home page: http://www.gnu.org/software/patch/
Summary: The GNU patch command, for modifying/upgrading files
The patch program applies diff files to originals. The diff command
is used to compare an original to a changed file. Diff lists the
changes made to the file. A person who has the original file can then
use the patch command with the diff file to add the changes to their
original file (patching the file).
List of contributors:
- patch: v2.7.5-17-g817d7d1 -> v2.7.6-15-g369dccc (fixes: CVE-2018-1000156).
- patch: v2.7.5-6-g3270d22 -> v2.7.5-17-g817d7d1.
- gnulib: v0.1-585-g2fda85e -> v0.1-1209-g24b3216.
- Updated to v2.7.5-6-g3270d22.
- Built with gnulib v0.1-585-g2fda85e. | <urn:uuid:e8177e4e-b58a-4eb7-9e1f-dfa9d37bca66> | 2.84375 | 270 | Documentation | Software Dev. | 106.466424 | 95,644,430 |
The Role of Sulfur Dioxide in Stratospheric Aerosol Formation Evaluated Using In-Situ Measurements in the Tropical Lower Stratosphere.
Geophys Res Lett. 2017 May 16;44(9):4280-4286
Authors: Rollins AW, Thornberry TD, Watts LA, Yu P, Rosenlof KH, Mills M, Baumann E, Giorgetta FR, Bui TV, Höpfner M, Walker KA, Boone C, Bernath PF, Colarco PR, Newman PA, Fahey DW, Gao RS
Stratospheric aerosols (SAs) are a variable component of the Earth's albedo that may be intentionally enhanced in the future to offset greenhouse gases (geoengineering). The role of tropospheric-sourced sulfur dioxide (SO2) in maintaining background SAs has been debated for decades without in-situ measurements of SO2 at the tropical tropopause to inform this issue. Here we clarify the role of SO2 in maintaining SAs by using new in-situ SO2 measurements to evaluate climate models and satellite retrievals. We then use the observed tropical tropopause SO2 mixing ratios to estimate the global flux of SO2 across the tropical tropopause. These analyses show that the tropopause background SO2 is about 5 times smaller than reported by the average satellite observations that have been used recently to test atmospheric models. This shifts the view of SO2 as a dominant source of SAs to a near-negligible one, possibly revealing a significant gap in the SA budget.
PMID: 29225384 [PubMed - in process] | <urn:uuid:9870a3a7-c226-4895-86a6-739337f0b5b3> | 2.640625 | 348 | Academic Writing | Science & Tech. | 32.024125 | 95,644,435 |
This question isn’t the same as this
I don’t want a mathematical proof or something of the sort. I want a verbal explanation that intuitively will convince me why this is true.
The way I see it, when you plot a continuous function like say the weight of all the people in the world. This will be continuous, right? Now for any given weight w, there will have to be some number of people who have that particular weight right? So why will the probability of someone having that weight w be zero?
The distribution of the weights of people in the world is of course discrete: there is only a finite number of distinct weights associated with the finite number of people that exist. However, you can certainly consider a continuous probability distribution, like the bell curve, which approximates the probability that a randomly chosen person has a given weight. In this idealized world, a random person’s weight may be an arbitrary real number, and this number can be known to arbitrary accuracy.
Now there is some finite probability that our random weight lies between 70 kg and 80 kg. Then the probability that it lies between 70 and 71 kg is roughly a tenth of that, because we’re considering only one-tenth of the interval, right? And the probability between 70.0 and 70.1 kg is a tenth further, and between 70.00 and 70.01 kg a tenth still. What do you suppose that leaves the probability that the weight is exactly 70.000… kg?
This is because you have a finite amount of people to check this. The requirement for a distribution on a finite set to be continuous isn’t a requirement at all, since in any function on a finite set (equipped with the discrete topology) is continuous. But this wouldn’t give you a continuous distribution in the sense of your statement. This would require the range to be some sort of continuum.
Rather consider saying “now” in a particular moment in time, measured 100% accurately (if that was possible).
Or maybe throwing a dart at a wall, hitting a particular spot on it.
Hope that helps.
Actually, it depends if you distribute weight over the people in the world or people of the world over possible weights they have. If you do the latter, the answer from Rahul would be the right one.
In intuitive terms:
Let’s say I ask you to throw a dart at a dartboard. To keep things simple, assume the face of the dartboard has an area of 1 square meter, and that you are equally likely to hit any spot on the dartboard. What is the probability that the dart will land at a particular point on a dartboard?
We can approximate this by discretizing the dartboard and thinking of it as a bunch of tiny squares that are 1 millimeter on each side. In that case, the probability of landing in a specific square is 1 in a million. But this is an approximation, and we’re not really happy with it, so perhaps we can divide the dartboard into “points” that are 1 micrometer on each side. Now that we have a finer granularity, the chances of hitting a specific point are 1 in a trillion.
Of course, this is still an approximation, and we want to be exact, so let’s look at individual molecules on the dartboard’s surface. What is the probability of hitting a specific molecule? It’ll be a tiny number — maybe something like 10^-30. In the pursuit of accuracy, we can go beyond molecules to atoms or even to quarks. As we get closer and closer to defining a point as being infinitesimally small, the probability of hitting that point gets infinitesimally close to 0.
In a continuous distribution, a “point” is the same as a “point” the dartboard — it’s dimensionless. You can get non-zero probabilities if you approximate the point with some interval, but as the interval shrinks your probability will approach 0.
In math terms:
Probability of an event = (# of outcomes that lead to that event) / (total # of outcomes)
In a continuous distribution, there’s an infinite number of outcomes, so the probability of a specific outcome is 1/infinity, which is 0. | <urn:uuid:c9ca954a-46ce-4a16-aa87-9192926b5fa5> | 2.890625 | 913 | Q&A Forum | Science & Tech. | 57.804925 | 95,644,454 |
2 - USGS National Geochemical Database: Recovering, repackaging, and repurposing 50+ years of historical data
Steven M Smith, firstname.lastname@example.org, David B Smith. Mineral and Environmental Resources Science Center, U.S. Geological Survey, Denver, Colorado 80225, United States
The U.S. Geological Survey's (USGS) National Geochemical Database (NGDB) contains inorganic analyses for approximately 1.4 million samples of rocks, sediments, soils, plants, water, minerals, and other materials collected since the early 1960s. Additionally, the NGDB project has recovered and compiled data from the U.S. Department of Energy's National Uranium Resource Evaluation (NURE) Hydrogeochemical and Stream Sediment Reconnaissance (HSSR) Program conducted during the late 1970s and early 1980s. The NURE HSSR databases contain analyses from about 398,000 sediment/soil and 335,000 groundwater/surface-water samples. All data are being repackaged into searchable and downloadable datasets on the USGS Mineral Resources On-Line Spatial Data website (http://mrdata.usgs.gov).
Although samples were collected to support geologic research and mineral exploration, the historical geochemical data and archived samples are increasingly being repurposed to identify hazards to the environment, to human and animal health, and to provide benchmarks for detecting temporal changes in the chemical environment.
Sunday, August 28, 2011 09:35 AM
Chemical Environmental Specific Databases and Searching Information Related to the Air, Water, and our Environment (09:00 AM - 11:50 AM)
Location: Colorado Convention Center | <urn:uuid:939d1cb5-162d-4618-bf0c-74ae1da40d55> | 3.03125 | 347 | News (Org.) | Science & Tech. | 26.772811 | 95,644,468 |
For quite some time, there have been arguments (and are going to stay with us for some more time) that the debate around A.I. versus Human Jobs is exaggerated, and humans will be having jobs, doing their work and earning the money. As much as it holds true, let me tell you it’s just one of the many arguments, to some it might be a perception but going with speculations, A.I. will outperform humans in all tasks.
Yes, the probability exists. And the chances are 50%. But for now, we need to ponder the same. What if it all becomes the reality? Think of that where A.I. won’t be able to outperform humans. The recent research suggests that machines will be writing a best-selling book by 2049 and will conduct surgery by 2053.
According to a survey of machine learning researchers on their beliefs about progress in AI, by the University of Oxford and Yale University, the chances are 50 percent that machines will outperform humans in all tasks within 45 years.
To dig into the matter, it is predicted that machines are going to be better than us at translating languages by 2024, writing high-school essays by 2026, driving a truck by 2027, working in retail by 2031, etc etc.
For that matter, all human jobs will be automated within the next 120 years, researchers predicted.
On the other side, making a comment on Twitter, Tesla & SpaceX founder, Elon Musk said that A.I. will beat us (or outperform us) by closer to 2030 to 2040. To the claims that A.I. will overtake us by 2060, he responded, “probably closer to 2030 to 2040 in my opinion.” 2060 would be a linear extrapolation, but progress is exponential, he added.
Well, Musk already has his plans to plug our brains into computers via working on a startup while on the other end, hoping to form a human colony on the planet Mars by 2030, this evolutionary shift, thanks to technology, is the absolute talking timeline of today’s times. Even the debate rages to explore that would humans be able to control the complex machines once executed? And even would they be able to survive?
We all are going to deal with such issues when A.I. will rule, and try to outperform humans. The researchers, as reported, put only a 5 percent chance on computers bringing about outcomes near the level of human extinction. But even 5 percent delivers a worrisome message, this is where mathematics helps!
“There is accumulating evidence that machines can overpower human intelligence in complex, though specific tasks,” says Eleni Vasilaki at the University of Sheffield in the UK.
“But there is little evidence that AI with human-like versatility will appear anytime soon,” she says.
The predictions are not much consistent and the researchers are at it for the same, for an instance, Asian respondents expecting these dates as mentioned above much sooner than North Americans, and every now and then, we get to face different arguments are surfacing, as that’s all the future will reveal itself but it appears what it has in its fold doesn’t sound good for ‘humans at work’.
While all of this keeps on coming, we need to make sure we keep education our first priority and developing the skill set other. 2060 is decades away, even 2030 is more than a decade away, but you just cannot chill by thinking the same. For a reminder, take this, the new Nutella jars have been redesigned by algorithms, not humans!
I read. I think. I write. A threat to humor, if one liners could kill. Twitter: @profylayush.
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A material in its normal condition has an effectively full valence band and an empty conduction band. Explain why the material is strongly compressed causing the two bands to overlap and the material changes its behavior to become much like a metal.© BrainMass Inc. brainmass.com July 17, 2018, 4:11 am ad1c9bdddf
The valence band is the highest range of electron energies where electrons are normally present at absolute zero. In semiconductors and insulators, ...
This solution involves an explanation of how a material can be compression to become like a metal. | <urn:uuid:9c6e68e8-18ba-42b1-97fe-16bc6eb051ac> | 3.546875 | 120 | Truncated | Science & Tech. | 45.650749 | 95,644,536 |
The Carina Nebula contains several ultra-hot stars, including these two star systems and the famous blue star Eta Carinae, which has the highest luminosity yet confirmed.
As well as producing incredible amounts of heat, these stars are also very bright, emitting most of their radiation in the ultraviolet and appearing blue in colour. They are so powerful that they burn through their hydrogen fuel source faster than other types of stars, leading to a "live fast, die young" lifestyle.
WR 25 is the brightest, situated near the centre of the image. The neighbouring Tr16-244 is the third brightest, just to the upper left of WR 25. The second brightest, to the left of WR 25, is a low mass star located much closer to the Earth than the Carina Nebula. Stars like WR 25 and Tr16-244 are relatively rare compared to other, cooler types. They interest astronomers because they are associated with star-forming nebulae, and influence the structure and evolution of galaxies.
WR 25 is likely to be the most massive and interesting of the two. Its true nature was revealed two years ago when an international group of astronomers led by Roberto Gamen, then at the Universidad de La Serena in Chile, discovered that it is composed of at least two stars. The more massive is a Wolf-Rayet star and may weigh more than 50 times the mass of our Sun. It is losing mass rapidly through powerful stellar winds that have expelled the majority of its outermost hydrogen-rich layers, while its more mundane binary companion is probably about half as massive as the Wolf-Rayet star, and orbits around it once every 208 days.
Massive stars are usually formed in compact clusters. Often the individual stars are so physically close to each other that it is very difficult to resolve them in telescopes as separate objects. These Hubble observations have revealed that the Tr16-244 system is actually a triple star. Two of the stars are so close to each other that they look like a single object, but Hubble's Advanced Camera for Surveys shows them as two. The third star takes tens or hundreds of thousands of years to orbit the other two. The brightness and proximity of the components of such massive double and triple stars makes it particularly challenging to discover the properties of massive stars.
WR 25 and Tr16-244 are the likely sources of radiation that is causing a giant gas globule within the Carina Nebula to slowly evaporate away into space, while possibly inducing the formation of new stars within it . The radiation is also thought to be responsible for the globule's interesting shape, prominently featured in earlier Hubble images, which looks like a hand with a "defiant" finger pointing towards WR 25 and Tr16-244.
These new observations were obtained by a team including astronomers from US, Chilean, Spanish, and Argentine institutions and led by Jesús Maíz Apellániz from the Instituto de Astrofísica de Andalucía in Spain. They are using Hubble as well as ground-based observatories in Spain, Chile, and Argentina to build a comprehensive catalogue of observations of all the massive stars in the Galaxy that are detectable at visible wavelengths.
Lars Christensen | alfa
What happens when we heat the atomic lattice of a magnet all of a sudden?
17.07.2018 | 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
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17.07.2018 | Materials Sciences
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The concept of entropy was introduced into the study of thermodynamics by Rudolph Clausius in 1856 to give a quantitative basis for the second law. It provides another variable to describe the state of a system to go along with pressure, volume, temperature and internal energy. If a system undergoes a reversible process during which it absorbs a quantity of heat ΔQ at absolute temperature T, Then the increase in the state variable called entropy S of the system is given by.
Entropy in thermodynamics formula
Like potential energy or internal energy, it is the change in entropy of the system which is important.
Change in entropy is positive when heat is added and negative when heat is removed from the system. Suppose, an amount of heat Q flow from a reservoir at temperature T 1 a conducting rod to a reservoir at temperature T 2 when T 1>T 2 . The change in entropy of the reservoir, at temperature T 1 which loses heat, decrease by Q/T 1 and of the reservoir at temperature T 2 , which gains heat, increases by Q/T 2. As T 1 > T 2 so Q/T will be greater than Q/T 1 i.e. Q/T 2 > Q/T 1.Hence:
It follows that in all natural processes where hear flows from one system to another, there is always a net increase in entropy. This is another statement of 2nd law of thermodynamics. According to this law:
“If a system undergoes a natural process,it will go in the direction that causes the entropy of the system plus the environment to increase.”
It is observed that a natural process tends to proceed towards a state of greater disorder. Thus, there is a relation between entropy and molecular disorder. For example an irreversible heat flow from a hot to a cold substance of a system increases disorder because the molecules are initially sorted out in hotter and cooler regions. This order is lost when the system comes to thermal equilibrium. Addition of heat to a system increases its disorder because the increase in average molecular speed and therefore, the randomness of molecular motion. Similarly, free expansion of gas increases its disorder because the molecules have the greater randomness of position after expansion than before. Thus in both examples, entropy is said to be increased.
We can conclude that only those processes are probable for which entropy of the system increases or remains constant. The process for which entropy remains constant is a reversible process; whereas for all irreversible processes, the entropy of all system increases.
Every time entropy increases, the opportunity to convert some heat into work is lost. For example there is an increase in entropy when hot and cold water are mixed. Then warm water which results cannot be separated into a hot layer and a cold layer. There has been no loss of energy but some of the energy is no longer available for conversion into work. Therefore increase in entropy means degradation of energy from a higher level where more work can be extracted to a lower level at which less or no useful work can be done. The energy in a sense is degraded, going from more orderly form to less orderly form. eventually ending up as thermal energy. | <urn:uuid:cbf89a3f-0b4f-4cd7-b945-72f7b8114259> | 3.796875 | 637 | Knowledge Article | Science & Tech. | 44.062826 | 95,644,593 |
The films were synthesized at BGU by Prof. Yuval Golan and PhD student Anna Osherov of the Department of Materials Engineering and the Ilse Katz Institute for Nanoscale Science and Technology. The letter was published this week in Nature Physics.
One of the important factors limiting solar-cell efficiency is that incident photons generate only one electron–hole pair, irrespective of the photon energy. Any excess photon energy is lost as heat.
Carrier Multiplication (CM) has been thought to be enhanced significantly in nanocrystalline materials such as quantum dots, owing to their discrete energy levels and enhanced Coulomb interactions.
The BGU team demonstrated that contrary to this expectation, for a given photon energy, carrier multiplication occurs more efficiently in bulk PbS and PbSe films than in nanocrystalline films of the same materials.
"Films developed at BGU show CM, in which each incoming photon (tiny quantity of sunlight) creates more than one electron-hole pair," Golan explains. "This can potentially be used for making more efficient solar cells. The new physics behind this work are that while CM has been mostly demonstrated in nanocrystalline materials ("quantum dots"), we now show that CM can be obtained also in single crystal ('bulk') films of lead sulfide and lead selenide."
Notably, the films were prepared using chemical solution deposition, an attractive, inexpensive deposition technique for which the Golan group at BGU has received considerable recognition. The research was carried out as part of an international collaboration with counterparts in France and the Netherlands.
J.J.H. Pijpers, R. Ulbricht, K.J. Tielrooij, A. Osherov, Y. Golan, C. Delerue, G. Allan and M. Bonn, "Assessment of Carrier Multiplication efficiency in bulk PbSe and PbS", Nature Physics (2009) in press.
About Ben-Gurion University of the Negev and American Associates
Ben-Gurion University of the Negev is a world-renowned institute of research and higher learning with some 19,000 students on campuses in Beer-Sheva, Sede Boqer and Eilat in Israel's southern desert. It is a university with a conscience, where the highest academic standards are integrated with community involvement, committed to sustainable development of the Negev. Founded in 1972, American Associates, Ben-Gurion University of the Negev plays a vital role in helping the University fulfill its unique responsibility to develop the Negev, reach out to its local community and its Arab neighbors, and share its expertise with the world.
Computer model predicts how fracturing metallic glass releases energy at the atomic level
20.07.2018 | American Institute of Physics
What happens when we heat the atomic lattice of a magnet all of a sudden?
18.07.2018 | Forschungsverbund Berlin
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
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Particle Physics found a large, hidden hole in the pyramid of Khufu, the largest pyramid at Giza, Egypt was built between 2600 and 2500 BC. The discovery, which was written in Nature, was made using imaging based on cosmic rays and could help scientists figure out how to actually built a mysterious pyramid.
At the heart of their technology is the tracking of particles called muons. They are very similar to electrons with the same charge and a quantum property called spin but 207 times heavier. This difference in mass is very important as it determines how these particles interact when they deal with the matter.
The high-energy electrons emit electromagnetic radiation, such as x-rays, when faced with the solid — as a result, lose energy and get stuck in it. Since the muon mass is much higher, the emission of electromagnetic radiation is suppressed to 207 times as compared with electrons. So muons do not stop so quickly when faced with any substance — they pierce right through him.
Muons are usually born in cosmic rays. The upper atmosphere of the Earth is continuously bombarded with charged particles from the sun and other sources outside our Solar system. It provides a high-energy cosmic rays that generate the muons and other particles in the chain reactions.
Since muons have a relatively large life span and relatively stable, they represent the most numerous particles in cosmic rays, visible at ground level. And while on the way lost a lot of energy, sometimes we see muons with a very high rate.the
To Detect these particles is quite easy. They leave a subtle mark "ionization" in its way — that is, knock out electrons from atoms, leaving the atoms charged. It is very convenient: scientists can use multiple detectors to track the path of the muon to the source of its origin. Moreover, if the path of the muon will be a lot of substance, it can lose all energy to get stuck in the material and to decompose (split up into other particles) before the direct detection.
These properties make muon a good candidate for capturing objects that generally is impervious or opaque to our usual methods of observation. Just as the bones leave a shadow on photographic film exposed to x-rays, heavy and dense object with high atomic number will provide shade, or reduce the number of muons that can pass through this object.
For the First time, muons were used in this way in 1955, when E. P. George measured the overburden of rocks above the tunnel, comparing the flux of muons on the outside and inside. The first known attempt to create a "myogram" took place in 1970, when Luis Alvarez was looking for the extended cavity of the second pyramid of Giza, but did not find one.
Over the last decade muon tomography has found a second wind. In 2007, the Japanese did myogram the crater of the volcano Asama to explore its internal structure.
Muon scans have also been used for the study of the remains of the reactor at Fukushima.the
The Simplest way to explore a large object like the pyramid using muons to look at the differences in the flow of muons passing through it. Solid pyramid will leave a shadow or reduce the number of muons passing through it. If the pyramid will be a big void, the muon flux will increase in the course of this emptiness. The greater the difference between "solid" and "hollow", so it is easier to find.
All you need is to sit somewhere nearby, to look a little upwards from the horizon to the pyramid and count the number of muons coming from all directions. Since cosmic muons have to be energetic to pass through a pyramid, and since our "eye" is relatively small, we have to sit and count some time, usually a few months to have enough muons. Just as we use two eyes make three-dimensional picture of the world in your head, we need two separate detector is the"eye" to get the three-dimensional image of the void inside the pyramid.
Interesting in the approach of this team that they chose three different technologies detectors for the study of the pyramid. The first of these somewhat old-fashioned but offers a higher resolution of the resulting images: photographic plates, which were blackened from ionization. Left them for a few months inside one of the famous chambers of the pyramid and analyzed in Japan after data collection.
For the second method used a plastic "scintillators", which produce a light flash during the passage of a charged particle through them. These types of detectors are used in several modern neutrino experiments.
Finally, the chamber filled with gas in which it is possible to control the ionization caused by charged particles, was used to directly view the newly discovered void.
An Electronic signal from these detectors is transmitted directly to Paris on 3G. Of course, the famous pyramid with three cavities and a giant empty gallery inside — quite difficult to myogram (it shows only black and white). So often these images compare with the computer simulation of cosmic muons and studied the pyramid, in parallel. Careful analysis of pictures of all three detectors and computer models have revealed a 30-foot void that was unknown until now, in the great pyramid of Giza. A striking success for the new tools.
Now this technique can help us to study the detailed shape of this emptiness. Although we don't know anything about the role of this structure, research projects involving scientists from other disciplines can be based on a new study. Nice to see how the ultra-modern particle physics helps us to shed light on ancient human culture....
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Stephen Hawking believes that humanity will soon have no choice but to leave Earth and seek a new home. Such statements famous physicist already played before. In his opinion, the chance for survival we have with you will only ari... | <urn:uuid:91e231b2-26fd-47ea-9f5f-8fbbe38adca0> | 4.1875 | 1,460 | Content Listing | Science & Tech. | 52.686505 | 95,644,626 |
New tools and approaches are becoming available for wildlife conservation managers to help support climate adaptation activities, but few studies have documented how practitioners have applied these tools and perceive their utility. We surveyed the literature and users of the NatureServe Climate Change Vulnerability Index (CCVI), a tool that is widely used in North America to assess species' vulnerability to climate change, to characterize 1) how the tool has been used; 2) the objectives addressed by projects using the tool; 3) novel approaches that might be useful to other users; 4) how the results contributed to climate change adaptation planning; and 5) needed improvements recognized by users of the tool. Responses from 25 CCVI users, representing state agencies and natural heritage programs, conservation organizations, and universities, combined with published reports from 20 CCVI assessments, indicated that the CCVI has been applied to large numbers of species from diverse taxonomic groups. Results from these assessments have been used to communicate about climate change vulnerability, select species to be prioritized for management, inform management decisions, identify monitoring needs, and inform land-acquisition decisions. Users of the CCVI have developed novel ways to address uncertainty in climate and species natural-history data, involve stakeholders, evaluate migratory species, address specific management questions, and combine outputs with the results of parallel spatial analyses. To address user needs, future iterations of the tool should address climate exposure in the full life cycle of migratory species; better examine species dependent on specific vegetation microhabitats; and improve treatment of the effects of climate on diseases, parasites, and natural enemies.
This handbook aims to provide reef managers with tools, information and recommendations on management of coral reef ecosystems. The handbook sections range from ecological history and biogeography, resilience as well as climate change issues to fisheries, governance and the monitoring of coral reef ecosystems.
Within each section are practical stand-alone ‘briefs’. These briefs offer concise information on particular reef-related issues, utilising some of the most recent scientific research to inform management actions. Each of the briefings is a unique grab-and-go resource. The accessible format also provides a useful resource for students, researchers, policy-makers and anyone interested in the future of Caribbean coral reefs.
The Priorities Tool is a watershed visualization and priorities decision support system for the North Pacific LCC developed by Ecotrust.
This spatially explicit, online tool is intended to assist the North Pacific LCC and other natural resource managers, individuals, and community organizations in accessing disparate data sources for understanding and visualizing a wide variety of data sets pertaining to species, threats and potential effects of climate change on freshwater and forest ecosystems throughout the North Pacific LCC geographic area.
Listening for the Rain starts a pluricultural conversation in which some Indigenous people who live in the central United States of America discuss their observations and understandings of, as well as responses to, climate change and variability. A team of Native and non-Native researchers and media artists worked together to document these stories. Not only does Listening for the Rain illustrate some of the environmental transformations distinguishing diverse Tribal landscapes, but the video also suggests some of the proactive solutions and ideas for addressing these issues that are currently being undertaken in Indian Country.
Featuring interviews with: Paulette Blanchard (Absentee Shawnee), Berrien Moore III, Renee McPherson, Dan Cornelius (Oneida), Casey Camp-Horinek (Ponca), Curtis Munoz (Kiowa), Kimberly Walden (Chitimacha), Roger Fragua (Jemez Pueblo), Ann Marie Chiscilly (Dine), Evaristo Cruz (Isleta del Sur Pueblo), Glenna Wallace (Eastern Shawnee), Maya Toralba (Kiowa/Comanche/Wichita), Wayne Kellogg (Chickasaw) and Tye Baker (Choctaw).
Forests in northern Minnesota will be affected directly and indirectly by a changing climate over the next 100 years. This assessment evaluates the vulnerability of forest ecosystems in Minnesota's Laurentian Mixed Forest Province to a range of future climates. Information on current forest conditions, observed climate trends, projected climate changes, and impacts to forest ecosystems was considered in order to draw conclusions on climate change vulnerability. Wet Forests, Forested Rich Peatlands, and Acid Peatlands were determined to be the most vulnerable to projected changes in climate, whereas Floodplain Forests, Fire-Dependent Forests, and Mesic Hardwood Forests were determined to be less vulnerable. Projected changes in climate and the associated ecosystem impacts and vulnerabilities will have important implications for economically valuable timber species, forest-dependent wildlife and plants, recreation, and long-range planning.
The publication, Considering Multiple Futures: Scenario Planning to Address Uncertainty in Natural Resource Conservation, presents scenario planning as an approach to help natural resource managers accommodate the uncertainty involved with combined threats to habitats and wildlife, including climate change, habitat fragmentation, land use, and invasive species. The publication presents the core elements of scenario planning, examines how scenario planning differs from other decision-support frameworks, identifies situations in which scenario planning could be used, explores the diversity of implementation options and approaches available to managers, and provides suggestions and additional resources for managers looking to embark on their own scenario planning effort. The report also includes 12 case studies representing a range of climate change-related scenario planning approaches for natural resource and conservation issues across the United States.
The Six Specific Goals of Kentucky's Climate Change Action Plan:
Goal 1: Conserve and restore functioning ecosystems in KentuckyGoal 2: Create or protect “key” or “concentrating” habitatsGoal 3: Implement multi-agency plans for wildlife corridors/connectivity in KentuckyGoal 4: Monitor fish, wildlife, and ecosystem responses to climate changeGoal 5: Evaluate the effectiveness of actions implemented as a result of Kentucky’s Climate Change chapter, and adaptively manage populations and habitats based on monitoring resultsGoal 6: Continue efforts to educate the public about wildlife conservation and continue efforts to stay optimally informed of current climate change predictions and observed climate change.
The application of ecosystem-based management (EBM) in marine environments has been widely supported by scientists, managers, and policy makers, yet implementation of this approach is difficult for various scientific, political, and social reasons. A key, but often overlooked, challenge is how to account for multiple and varied human activities and ecosystem services and incorporate ecosystem-level thinking into EBM planning. We developed methods to systematically identify the natural and human components of a specific ecosystem and to qualitatively evaluate the strength of their interactions. Using the Gulf of Maine marine ecosystem as a case study, we show how these methods may be applied, in order to identify and prioritize the most important components to be included in an EBM plan – particularly the human activities that are the strongest drivers of ecosystem change and the ecosystem services most threatened by cumulative and indirect effects of these activities.
Adaptation in forestry is sustainable forest management that includes a climate change focus. Climate change over the next 100 years is expected to have significant impacts on forest ecosystems. The forestry community needs to evaluate the long-term effects of climate change on forests and determine what the community might do now and in the future to respond to this threat. Management can influence the timing and direction of forest adaptation at selected locations, but in many situations society will have to adjust to however forests adapt. Adapting to climate change in the face of the uncertain timing of impacts means we must have a suite of readily available options. A high priority will be coping with and adapting to forest disturbance while maintaining the genetic diversity and resilience of forest ecosystems. A framework for facilitating adaptation in forestry is discussed and a review of adaptive actions presented.
Presentation from the International Workshop on Vulnerability and Adaptation to Climate Change: From Practice to Policy on May 11-12, New Delhi by Dr. Pushpam Kumar of the Institute of Economic Growth.
This presentation highlights why biodiversity loss and unsustainable use of ecosystems services affects and will continue to affect human well-being. The author surmises by stating that ecosystems management and biodiversity conservation have strong bearing on the success of adaptation strategies. | <urn:uuid:2261e490-5fcb-4a2e-8400-c780a81e0ce4> | 3.5 | 1,675 | Content Listing | Science & Tech. | -3.012523 | 95,644,634 |
Bacteria inhabiting deep-sea hot vents as symbiotic tenants of mussels are equipped with a whole arsenal of toxins – more than any known pathogen. Find out about this discovery, and why it is rather healthy than harmful for the mussels, in a new publication by MPI scientists in the open-access journal eLife
Imagine you have a tenant living in your house. They’re keeping your fridge topped up. But in addition to this, they’re producing all kinds of toxic substances. More harm than good? Not necessarily; it all depends what you’re using the toxins for.
Deep-sea hot vents are one of the most unusual habitats on Earth: At first sight they appear hostile and uninviting, but in fact, they are teeming oases of life. Likewise, their unique inhabitants are always surprising us. Find out how toxic tenants can also be beneficial in a new publication by an international research team led by Jillian Petersen from the Max Planck Institute (MPI) for Marine Microbiology, published in the open-access journal eLife.
Mussels of the genus Bathymodiolus, related to the well-known blue mussel, are among the most dominant inhabitants of hot vents in the deep ocean. In their gills, they house so-called chemoautrotrophic symbionts. These symbionts include sulfur-oxidizing bacteria, which convert substances normally not used by the mussels into tasty sugars.
Jillian Petersen and her colleagues have now taken a closer look at the genes that some of the symbiotic tenants of deep-sea mussels contain in their genomes. To their surprise, what they found was a vast array of hazardous substances. The symbiotic bacteria command an arsenal of genes that are responsible for the production of toxins. The number of toxins is impressive: With up to 60 toxins, the microorganism’s arsenal is better stocked than many nasty germs such as those that cause pest and cholera. However, down in the deep sea, the bacteria leave their host unharmed. In fact, they promote the health of their mussel hosts. How is this possible?
“We suspect that they bacteria have tamed these toxins”, explains Petersen. “Thus, they can now take advantage of them for the benefit their host.” Two kinds of beneficial effects of the toxins are possible: On the one hand, they might help mussels and bacteria to find and to recognize each other, essential steps to establishing a successful symbiosis. On the other hand, the toxins may help the mussel to defend itself against parasites.
“Symbioses are usually assumed to have only one benefit – the symbionts either help the host to feed or to defend itself. Our study shows that the partnership of Bathymodiolus and the sulfur-oxidizing bacteria seems to provide both: defence and food. That is very unusual”, emphasizes Lizbeth Sayavedra, who conducted the research as part of her doctoral thesis. The tenant not only fills the fridge, it also keeps the burglars out.
In the next steps, Petersen now wants to investigate the details of this defence mechanism. The research team has developed a method proving that at least one of the toxins is exported to the mussel tissue. “Our results give fresh impetus to the research on the role of parasites and pathogens in the deep sea”, says Petersen, who has recently established an independent research group at the University of Vienna.
“The Bathymodiolus symbionts produce more of these supposedly harmful substances than any known pathogen”, adds Liz Sayavedra. “Who knows – maybe one day we’ll discover that some of the genes that are currently annotated as toxins may have first evolved through such beneficial interactions.”
Sayavedra et al. (2015) Abundant toxin-related genes in the genomes of beneficial symbionts from deep-sea hydrothermal vent mussels. eLife 2015;10.7554/eLife.07966
http://www.mpi-bremen.de Website of the MPI
http://elifesciences.org/content/early/2015/09/14/eLife.07966 Original article
Dr. Manfred Schloesser | Max-Planck-Institut für marine Mikrobiologie
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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.
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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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New Perspective on Plankton Shell Formation
Foraminifera Orbulina Universa eating a small copepod. Credit: Oscar Branson/ANU.
The carbonate shells of tiny marine plankton, foraminifers, are important archives of geochemical records of past climates. Understanding how these plankton make their shells is essential to correctly interpret the geochemical climate signals recorded in them. Using electron microscopy and infrared spectrometry on ultra-thin slices cut from these shells, Dorrit Jacob from Macquarie University in Australia, together with her colleagues from the Australian National University and the GFZ German Research Centre for Geosciences in Potsdam, Germany, has resolved puzzling issues surrounding foraminifer shells.
The researchers have discovered that, contrary to long-standing textbook knowledge, these shells do not form as calcite, but instead, are originally formed as the metastable carbonate vaterite and only later transform into calcite. "These findings are important for understanding how chemical elements are incorporated into the shells and how to read these climate archives correctly," explains Dorrit Jacob. "This promises to resolve hotly debated discrepancies between observations on natural shells and those seen in chemical laboratory experiments."
The presence of vaterite instead of calcite in these abundant organisms also means that foraminifer shells are much more susceptible to ocean acidification than has been previously thought, which carries drastic ramifications for their survival in the future oceans.
This article has been republished from materials provided by the GFZ German Research Centre for Geosciences. Note: material may have been edited for length and content. For further information, please contact the cited source.
D. E. Jacob, R. Wirth, O. B. A. Agbaje, O. Branson, S. M. Eggins. Planktic foraminifera form their shells via metastable carbonate phases. Nature Communications, 2017; 8 (1) DOI: 10.1038/s41467-017-00955-0.
Doctors Rely on More Than Just Data During a DiagnosisNews
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In this chapter we’re going to look at how to store, process, and interact with external sources of data from our Ruby programs. In Chapter 4 we briefly looked at how to load files to get data into an application, but this chapter will extend upon that greatly and allow you to create files from scratch from your Ruby programs.
KeywordsRelational Database File Object Structure Query Language Temporary File Standard Input
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why is evaporation important to the water cycle
Cycle that involves the continuous circulation of water in the Earth-atmosphere system. Of the many processes involved in the hydrologic cycle, the most important are evaporation, transpiration, condensation, precipitation, and runoff. Although the total amount of water within the cycle remains essentially constant, its distribution among the various processes is continually changing. Evaporation, one of the major processes in the cycle, is the transfer of water from the surface of the Earth to the atmosphere. By evaporation, water in the liquid state is transferred to the gaseous, or vapour, state. This transfer occurs when some molecules in a water mass have attained sufficient kinetic energy to eject themselves from the water surface. The main factors affecting evaporation are temperature, humidity, wind speed, and solar radiation. The direct measurement of evaporation, though desirable, is difficult and possible only at point locations. The principal source of water vapour is the oceans, but evaporation also occurs in soils, snow, and ice. Evaporation from snow and ice, the direct conversion from solid to vapour, is known as sublimation. Transpiration is the evaporation of water through minute pores, or stomata, in the leaves of plants. For practical purposes, transpiration and the evaporation from all water, soils, snow, ice, vegetation, and other surfaces are lumped together and called evapotranspiration, or total evaporation. Water vapour is the primary form of atmospheric moisture. Although its storage in the atmosphere is comparatively small, water vapour is extremely important in forming the moisture supply for dew, frost, fog, clouds, and precipitation. Practically all water vapour in the atmosphere is confined to the troposphere (the region below 6 to 8 miles [10 to 13 km] altitude).
The transition process from the vapour state to the liquid state is called condensation. Condensation may take place as soon as the air contains more water vapour than it can receive from a free water surface through evaporation at the prevailing temperature. This condition occurs as the consequence of either cooling or the mixing of air masses of different temperatures. By condensation, water vapour in the atmosphere is released to form precipitation. Precipitation that falls to the Earth is distributed in four main ways: some is returned to the atmosphere by evaporation, some may be intercepted by vegetation and then evaporated from the surface of leaves, some percolates into the soil by infiltration, and the remainder flows directly as surface runoff into the sea. Some of the infiltrated precipitation may later percolate into streams as groundwater runoff. Direct measurement of runoff is made by stream gauges and plotted against time on hydrographs. Most groundwater is derived from precipitation that has percolated through the soil. Groundwater flow rates, compared with those of surface water, are very slow and variable, ranging from a few millimetres to a few metres a day. Groundwater movement is studied by tracer techniques and remote sensing. Ice also plays a role in the hydrologic cycle. Ice and snow on the Earth s surface occur in various forms such as frost, sea ice, and glacier ice. When soil moisture freezes, ice also occurs beneath the Earth s surface, forming permafrost in tundra climates. About 18,000 years ago glaciers and ice caps covered approximately one-third of the Earth s land surface. Today, about 12 percent of the land surface remains covered by ice masses.
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Posted on April 17, 2012 in by Atmospheric icing occurs whenPwaterPdropletsPin thePatmospherePfreezePon objects they contact. This can be extremely dangerous toPaircraft, as the built-upPicePchanges thePaerodynamicsPof the flight surfaces, which can increase the risk of a subsequentPstallingPof thePairfoil. AnP avalanche Pis a sudden, rapid flow ofPsnowPdown a slope, occurring when either natural triggers, such as loading from new snow or rain, or artifical triggers, such as snowmobilers, explosives or backcountry skiers, overload the snowpack. A cloud is a visible mass of liquid droplets or frozen crystals made of water and/or various chemicals suspended in the atmosphere above the surface of a planetary body. They are also known as aerosols. Clouds in Earth s atmosphere are studied in the cloud physics branch of meteorology. Two processes, possibly acting together, can lead to air s becoming saturated: cooling the air or adding water vapor to the air. In general, precipitation will fall to the surface; an exception is virga, which evaporates before reaching the surface. Condensation is the change of the physical state of matter from gaseous phase into liquid phase, and is the reverse of vaporization. When the transition happens from the gaseous phase into the solid phase directly, the change is called deposition. In meteorology, a cyclone is an area of closed, circular fluid motion rotating in the same direction as the Earth. This is usually characterized by inward spiraling winds that rotate anticlockwise in the Northern Hemisphere and clockwise in the Southern Hemisphere of the Earth. A cyclone is a synonym for hurricane.
Most large-scale cyclonic circulations are centered on areas of low atmospheric pressure. The largest low-pressure systems are cold-core polar cyclones and extratropical cyclones which lie on the synoptic scale. Warm-core cyclones such as tropical cyclones, mesocyclones, and polar lows lie within the smaller mesoscale. Dead water is the nautical term for a strange phenomenon which can occur when a layer of fresh or brackish water rests on top of denser salt water, without the two layers mixing. A ship powered by direct thrust under the waterline (such as a propeller), traveling in such conditions may be hard to maneuver or can even slow down almost to a standstill. Much of the energy from the ship s propeller only results in waves and turbulence between the two layers of water, leaving a ship capable of traveling at perhaps as little as 20% of its normal speed. P Dew is water in the form of droplets that appears on thin, exposed objects in the morning or evening. As the exposed surface cools by radiating its heat, atmospheric moisture condenses at a rate greater than that at which it can evaporate, resulting in the formation of water droplets. When temperatures are low enough, dew takes the form of ice; this form is called frost (frost is, however, not frozen dew). Don Juan Pond is a shallow, flat-bottom, hyper-saline pond. It has greaterPsalinityPthan thePDead SeaPor evenPLake Assal. It has been claimed that the salinity in Don Juan Pond is over 18 times the ocean s salinity, compared to that of the Dead Sea at about 8 times that of the ocean. The fact that it is the only one of the Antarctic hypersaline lakes that almost never freezes is an indication of its top rank in salinity among the world s lakes. Previous Post
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Phospholipids are unusual and important to cell structure because:
A) they are part of DNA
B) they are found only in animals
C) they contain fatty acids
D) They have a polar and non-polar end
E) They are an important energy carrier molecule© BrainMass Inc. brainmass.com July 18, 2018, 6:39 am ad1c9bdddf
Phospholipids are unusual in that they have a polar and a non-polar end. In this sense, they are called ... | <urn:uuid:4de30981-68f7-4860-98b6-8c3f23788e9f> | 2.890625 | 116 | Truncated | Science & Tech. | 64.4275 | 95,644,675 |
Kirchhoff’s Law of Thermal Emission asserts that, given sufficient dimensions to neglect diffraction, the radiation contained within arbitrary cavities must always be black, or normal, dependent only upon the frequency of observation and the temperature, while independent of the nature of the walls. With this in mind, simple tests were devised to demonstrate that Kirchhoff’s Law is invalid. It is readily apparent that all cavities appear black at room temperature within the laboratory. However, two completely different causes are responsible: 1) cavities made from good emitters self-generate the appropriate radiation and 2) cavities made from poor emitters are filled with radiation already contained in the room, completely independent of the temperature of the cavity. The distinction between these two scenarios can be made by placing a heated object near either type of cavity. In the first case, the cavity emission will remain essentially undisturbed. That is because a real blackbody can do work, instantly converting incoming radiation to an emission which corresponds to the temperature of its walls. In the second case, the cavity becomes filled with radiation which is not characteristic of its own temperature. Contrary to current belief, cavity radiation is entirely dependent on the nature of the walls. When considering a perfect reflector, the radiation will not be black but, rather, will reflect any radiation which was previously incident upon the cavity from the surroundings. This explains why microwave cavities are resonant, not black, and why it is possible to acquire Ultra High Field Magnetic Resonance Imaging (UHFMRI) images using cavity resonators. Conversely, real blackbodies cannot contain any radiation other than that which is characteristic of the temperature of their walls, as shown in Planck’s equation. Blackbody radiation is not universal, Kirchhoff’s Law is false, and cavity radiation is absolutely dependent on the nature of the walls at every frequency of observation. Since they were derived from this law, the concepts of Planck time, Planck temperature, Planck length, and Planck mass are not universal and are devoid of any fundamental meaning in physics.
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Over the past 18 months, astronomers have painstakingly tracked a dozen tiny moons that they found circling the giant planet Jupiter.
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With winter's chill fading away, this is a great time to gaze up into the stars — and to be ready for an evening appearance by fleet-footed Mercury. This month's astronomy podcast guides you around the nighttime sky.
February's astronomy podcast offers you a trio of bright planets to spot before dawn and a plethora of bright stars to check out each evening.
Get ready for a celestial event — a total lunar eclipse during the month's second full Moon and near lunar perigee — that hasn't happened in 35 years!
Thick sheets of water ice, some barely buried beneath the surface and likely more than 100 meters thick, have been spotted on several Martian cliff faces.
January's astronomy podcast describes how to spot Mercury, Mars, Jupiter, and Saturn in the predawn sky during January — plus you'll learn about a "trifecta" full Moon at month's end.
Two total lunar eclipses occur this year, the first since late 2015, in January and July. Meanwhile, three solar eclipses take place in 2018 — all of them only partial cover-ups.
More than a dozen times each year, we experience a pulse of "shooting stars" from an annual meteor shower. Sky & Telescope predicts that the two best meteor showers in 2018 will be the Perseids in mid-August and the Geminids in mid-December.
Astronomers' recent observations of our first-known interstellar visitor reveal that it is very strange indeed.
For a young woman who stared too long on August 21st, the partially eclipsed Sun left a lasting impression — on her retinas.
A new analysis reveals that the gigantic impact that led to the Moon's formation might have also switched on Earth's magnetic field.
As you'll hear in December's astronomy podcast, early risers are treated with views of Jupiter (obvious), Mars (not as easy), and Mercury (timing is everything!).
The U.S. National Science Foundation will continue to fund the iconic radio dish, though at a much-reduced level, as it seeks partners to share in the facility's operation.
Rapid-response observations by major observatories shows that the first-known interstellar visitor is 10 times longer than it is wide.
The arrival of an object from beyond the solar system caught astronomers by surprise — but that doesn't mean that they were unprepared to study it.
Observations from NASA's MAVEN spacecraft reveal that the solar wind causes unexpected interactions with the Red Planet's weak magnetism.
As you'll hear in this month's astronomy podcast, Venus and Jupiter are putting on quite a show low in the east before dawn.
Telescopes only picked it up a week ago, but it's likely been traveling through interstellar space for millions of years. | <urn:uuid:fdb2f44d-6fdb-45ad-bf07-2e4d99ac6961> | 3.390625 | 827 | Content Listing | Science & Tech. | 52.341802 | 95,644,702 |
OpenPIV - what is it for?
OpenPIV is an initiative of scientists to develop a software, algorithms and methods for the state-of-the-art experimental tool of Particle Image Velocimetry (PIV) which are free, open source, and easy to operate. OpenPIV is the successor of the well known URAPIV software - it is faster, more friendly and much more flexible. OpenPIV is provided using Matlab, Python or 32bit Windows executable (based on C++ and Qt source).
How to cite this work
Taylor, Z.J.; Gurka, R.; Kopp, G.A.; Liberzon, A.; , "Long-Duration Time-Resolved PIV to Study Unsteady Aerodynamics," Instrumentation and Measurement, IEEE Transactions on , vol.59, no.12, pp.3262-3269, Dec. 2010 doi: 10.1109/TIM.2010.2047149 URL: http://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=5464317&isnumber=5609237
How to download the software
Please note that there are two versions of the GUI:
- older Matlab version, before 2014b: https://github.com/OpenPIV/openpiv-matlab/releases/tag/v1.1
- Newer Matlab versions, use https://github.com/OpenPIV/openpiv-matlab/archive/master.zip or clone this repository
How to contribute ?
- Open Github account
- Visit our Git repositories through https://github.com/OpenPIV
- Fork your favorite repository
- Fix, commit, push to your repository and send us a pull request.
- register on openpiv-develop mailing list through https://groups.google.com/forum/#!forum/openpiv-users
Getting started tutorials
Matlab - see the screencast http://youtu.be/yg-LjAt-v3Q
C++ - not ready yet
Spatial and Temporal Analysis Toolbox http://www.openpiv.net/openpiv-spatial-analysis-toolbox/
Pressure from PIV http://www.openpiv.net/openpiv-pressure
Support and documentation
How to get support? Where to ask questions? Use one of the following:
- Google group https://groups.google.com/forum/#!forum/openpiv-users
- e-mail to email@example.com
- Comment using Github page | <urn:uuid:ce637d2e-6fe8-4b7b-bfe9-3cd766fe5dd3> | 2.6875 | 561 | About (Org.) | Software Dev. | 59.591398 | 95,644,712 |
Conventional oil and gas development in northern Pennsylvania altered bird communities, and the current massive build-out of shale-gas infrastructure may accelerate these changes, according to researchers in Penn State's College of Agricultural Sciences.
The commonwealth's Northern Tier -- one of the largest blocks of Eastern deciduous forest in the entire Appalachian region -- is an important breeding area for neotropical migrant songbirds. These diminutive, insect-eating creatures, which breed in Pennsylvania and winter in Central and South America, contribute greatly to the health of forests.
But they are being negatively affected in areas where there are high densities of shallow oil and gas wells, says Margaret Brittingham, professor of wildlife resources, who conducted a study of bird communities in the Allegheny National Forest. The national forest, on the extensively forested Allegheny Plateau in northwestern Pennsylvania, has more than 14,000 active oil and gas wells. Although the footprint of a shallow well is much smaller than the immense Marcellus Shale well pads now being built across the region, clusters of shallow wells, service roads, pads and pipelines create networks of disturbance that fragment forests, changing songbird communities, Brittingham explained.
"The cumulative effect of many small-scale disturbances within the forest is resulting in the homogenization of bird communities, with species that inhabit the interior forest, such as black-throated blue warblers, ovenbirds and Blackburnian warblers being pushed out, and species that prefer living in edge habitat and near people and development, such as robins, blue jays and mourning doves, moving in," she said.
"Biotic homogenization is a subtle process by which generalists replace specialists, with common and widespread species tending to become more abundant and habitat specialists declining. Our results revealed changes in avian guilds resulting from oil and gas development and suggest that a loss of community uniqueness is a consequence."
The study, done in collaboration with the U.S. Department of Agriculture's Northern Forest Research Station, took place over three years. Lead researcher Emily Thomas, at the time a graduate student advised by Brittingham, surveyed birds in 50-acre blocks selected for their varied amount of oil and gas development.
Thomas completed her master's degree in wildlife and fisheries science and is currently an instructor in the wildlife technology program at Penn State DuBois.
In a recently published issue of the Journal of Wildlife Management, the researchers documented the presence or absence of different songbird species in a range of landscapes, including undisturbed forest, low-density oil and gas development, and high-density development. They catalogued the abundance and diversity of songbirds in the study areas, which spanned two types of forest -- northern hardwood and oak.
"We wanted to find out what the well pads, roads, pipelines and other openings created by oil and gas development are doing to bird populations," said Brittingham. "We compared and contrasted the abundance and diversity of birds near well sites to bird communities in reference sites far away from disturbances in the big woods, and what we found was compelling." Forest interior species declined in proximity to the wells and at a rate that was roughly proportional to the intensity of gas development. Songbird species that prefer early successional habitat increased in abundance on the edge of gas development.
In addition, Brittingham noted, the generalist bird species that do better around people and tend to be common wherever there are people or development were more abundant near oil and gas development than within undisturbed forest -- potentially displacing the forest specialists.
The expansive development of Marcellus Shale gas, which began within the core forests of northcentral Pennsylvania around 2007, is increasing exponentially. Deep, horizontal shale gas wells differ substantially from shallow, conventional oil and gas wells in many ways.
Shale-gas well pads are immense but occur at a much lower density. Drillers install pad substrate of stone to support heavy equipment, and the drillers use a much greater quantity of water for hydrofracturing. That technology demands greatly increased levels of truck traffic on wider, more highly engineered roads. Brittingham and her students are currently studying the effects of shale-gas development on birds to determine how it affects avian communities.
"Birds are easy to study and survey to gauge the impacts of gas development because they are abundant, respond quickly to habitat change and are early indicators of problems," she said. "The bottom line is we are going to have resource extraction in this state, but the forests on top of it are providing clean water, clean air, climate regulation and a host of other ecological values.
"We need to maintain them as healthy, functioning ecosystems while extracting the gas. We hope our research will help to determine where thresholds of change occur and to identify areas where gas development should be avoided or minimal at best to protect these valuable ecological services that are provided free-of-charge to all of us."
This USDA Bureau of Forestry funded this work.
A'ndrea Elyse Messer | Eurek Alert!
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:5593c37e-2263-48d7-a2ef-ef566e546937> | 3 | 1,627 | Content Listing | Science & Tech. | 32.046885 | 95,644,717 |
The ideal gas law is an equation of state of a hypothetical ideal gas. It is an approximation to the behaviour of many gases under many conditions. The ideal gas law however has many limitations. Emile Clapeyron was the first the state the equation in 1834 as a combination of Boyle’s law and Charles’ law. The ideal gas law is
PV = nRT
Where P is pressure, V is volume, n is the number of moles, T is the temperature, and R is the universal gas constant.
In Statistical mechanics, the ideal gas law is
PV = NkT
Where P is the absolute pressure, V is the volume, N is the number of particles in the gas, k is the Boltzmann constant and T is the temperature.
These equations only apply to ideal gas. There are many other forms of equations of states. The ideal gas law neglects both molecular size and intermolecular attractions. It is most accurate for monatomic gases at high temperatures and low pressures. The neglect of molecular size becomes less important for lower densities.© BrainMass Inc. brainmass.com July 22, 2018, 6:51 am ad1c9bdddf | <urn:uuid:08ec12e8-d09d-45da-a17e-bdfd72d25801> | 3.859375 | 252 | Knowledge Article | Science & Tech. | 56.706538 | 95,644,733 |
Modeling aerosol optical properties in Amazonia obtained by AERONET and preliminary radiative forcing study
Paixão, Universidade de São Paulo, email@example.com
Artaxo, Universidade de São Paulo, firstname.lastname@example.org
Holben, NASA Goddard Space Flight Center, email@example.com
Schafer, NASA Goddard Space Flight Center, firstname.lastname@example.org
This study presents the first results of a model of aerosol optical properties based on aerosol optical depth (AOD) ranges for Amazonian AERONET/NASA (Aerosol Robotic Network) sites such as Abracos Hill (RO), Alta Floresta (MT), Rio Branco (AC), Cuiabá (MT) and Campo Grande (MS). The biomass burning emissions in Amazonia are very important in the global radiative balance and understanding how it changes the atmospheric composition during the year can let us estimate better the radiative impact. We distinguish 3 main seasons: wet, dry and biomass burning. In each season the data were separated in 13 AOD cases (0.1 AOD 500nm steps until AOD higher than 1.6). The studied optical properties include single scattering albedo, complex refractive index, asymmetric factor, column water vapor, volume size distribution, radiative forcing and forcing efficiency. A comparison was made too with model based on single scattering albedo instead optical depth.
These results contribute to a better regional parameterization used in look up tables such as from MODIS and regional models of transport and dispersion of pollutants. | <urn:uuid:ade153d7-986e-45f7-ab3d-b551104c5d04> | 2.78125 | 355 | Academic Writing | Science & Tech. | 24.29 | 95,644,749 |
On November 12 at 4 a.m. EST the National Hurricane Center issued the last advisory on Extra-Tropical Cyclone Kate, located several hundred miles south-southeast of Cape Race, Newfoundland. NOAA's GOES-East satellite captured a visible light image of the storm.
A NOAA GOES-West satellite visible image extra-tropical storm Kate on Nov. 12 at 1445 UTC (9:45 a.m. EST) showed the storm over 400 miles southeast of Newfoundland, Canada. Most of the clouds associated with the post-tropical storm were north and east of the center. Forecaster Beven of the National Hurricane Center said, "Satellite imagery indicates that Kate has merged with a baroclinic zone over the north Atlantic and is now an extratropical cyclone."
Kate Reached Hurricane Strength
On Nov. 10, the RapidScat instrument that flies aboard the International Space Station saw Hurricane Kate north of the Bahamas and its strongest winds were north of the center. Maximum sustained winds in both areas were as strong as 30 meters per second (67 mph/108 kph). On Nov. 11, those winds increased to hurricane force. Hurricane force winds extended outward up to 35 miles (55 km) from the center and tropical storm force winds extend outward up to 205 miles (335 km).
At 10 a.m. EST (1500 UTC) on Nov. 11 the center of Hurricane Kate was located near latitude 36.8 North, longitude 60.5 West. That put Kate's center about 395 miles (635 km) northeast of Bermuda and about 780 miles (1,260 km) south-southwest of Cape Race Newfoundland.
An Infrared Look at Kate
On Nov. 12 at 05:17 UTC (12:17 a.m. EST) infrared imagery from the Atmospheric Infrared Sounder or AIRS instrument aboard NASA's Aqua satellite showed fragmented strong storms east and north of Kate's center where cold cloud top temperatures were near -63F/-53C. Storms with cloud tops that cold (and high in the troposphere) have been shown to generate heavy rain.
Aqua satellite showed fragmented strong storms east and north of Kate's center.
Kate Weakens and Becomes Extra-Tropical
At 4 a.m. EST on Nov. 12, Kate was classified as an extra-tropical storm. That means that a tropical cyclone has lost its "tropical" characteristics. The National Hurricane Center defines "extra-tropical" as a transition that implies both poleward displacement (meaning it moves toward the north or south pole) of the cyclone and the conversion of the cyclone's primary energy source from the release of latent heat of condensation to baroclinic (the temperature contrast between warm and cold air masses) processes. It is important to note that cyclones can become extratropical and still retain winds of hurricane or tropical storm force.
At 4 a.m. EST on Nov. 12, Kate's maximum sustained winds were near 60 knots (70 mph). Kate was centered near 40.7 degrees north latitude and 50.8 degrees west longitude, about 430 miles south-southeast of Cape Race, Newfoundland, Canada. Kate was moving to the east-northeast at 23 knots (26 mph). Minimum central pressure was 983 millibars. The post-tropical cyclone is expected to accelerate toward the east-northeast and northeast.
The National Hurricane Center expects extra-tropical storm Kate to continue weakening, but slowly over the next couple of days. The NHC forecast keeps maximum sustained winds near 45 knots (50 mph) through Nov. 15 and by Nov. 16, Kate is expected to become absorbed by an extra-tropical low pressure area.
Additional information on this system can be found in High Seas Forecasts issued by the National Weather Service at http://www.
Rob Gutro | EurekAlert!
Abrupt cloud clearing events over southeast Atlantic Ocean are new piece in climate puzzle
23.07.2018 | University of Kansas
Global study of world's beaches shows threat to protected areas
19.07.2018 | NASA/Goddard Space Flight Center
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
23.07.2018 | Science Education
23.07.2018 | Health and Medicine
23.07.2018 | Life Sciences | <urn:uuid:ace040c4-5a53-404f-87ea-524ef9b8410d> | 2.9375 | 1,379 | Content Listing | Science & Tech. | 52.307454 | 95,644,754 |
Restoration can be viewed as the process of reestablishing both exogenous drivers and internal feedbacks that maintain ecosystems in a desirable state. Correcting exogenous and abiotic drivers is clearly necessary, but may be insufficient to achieve desired outcomes in systems with self-organizing biotic feedbacks that substantially influence ecological stability and timing of responses. Evidence from a broad suite of systems demonstrates the prevalence of biotic control over key ecosystem attributes such as hydroperiod, nutrient gradients, and landform that are most commonly conceived of as exogenously controlled. While a general theory to predict conditions under which biotic controls exert such strong feedbacks is still nascent, it appears clear that the Greater Everglades/South Florida landscape has a high density of such effects. The authors focus on three examples of biotic control over abiotic processes: hydroperiod and discharge controls exerted by peat accretion in the ridge-slough landscape; phosphorus (P) gradients that emerge, at least in part, from interactions between accelerated peat accretion rates, vegetation structure and fauna; and reinforcing feedbacks among land elevation, aquatic respiration, and carbonate dissolution that produce local and landscape basin structure. The authors propose that the unifying theme of biogeomorphic landforms in South Florida is low extant topographic variability, which allows reciprocal biotic modification of local site conditions via mechanisms of peat accretion (including via effects of landscape P redistribution on primary production) or limestone dissolution. Coupling these local positive feedbacks, which drive patch expansion, with inhibitory or negative feedbacks on site suitability at distance, which serve to constrain patch expansion, provide the mechanistic basis for landscape pattern formation. The spatial attributes (range and isotropy) of the distal negative feedback, in particular, control pattern geometry; elucidating the mechanisms and properties of these distal feedbacks is critical to restoration planning.
Mendeley saves you time finding and organizing research
Choose a citation style from the tabs below | <urn:uuid:5c2ab4d0-3795-49e7-b7e7-9ae5b7e5b394> | 2.75 | 405 | Academic Writing | Science & Tech. | -11.151899 | 95,644,755 |
Find some triples of whole numbers a, b and c such that a^2 + b^2 + c^2 is a multiple of 4. Is it necessarily the case that a, b and c must all be even? If so, can you explain why?
Try to solve this very difficult problem and then study our two suggested solutions. How would you use your knowledge to try to solve variants on the original problem?
Make a set of numbers that use all the digits from 1 to 9, once and once only. Add them up. The result is divisible by 9. Add each of the digits in the new number. What is their sum? Now try some. . . .
I am exactly n times my daughter's age. In m years I shall be ... How old am I?
Prove that if a^2+b^2 is a multiple of 3 then both a and b are multiples of 3.
Use the numbers in the box below to make the base of a top-heavy pyramid whose top number is 200.
Find the smallest positive integer N such that N/2 is a perfect cube, N/3 is a perfect fifth power and N/5 is a perfect seventh power.
Carry out cyclic permutations of nine digit numbers containing the digits from 1 to 9 (until you get back to the first number). Prove that whatever number you choose, they will add to the same total.
Blue Flibbins are so jealous of their red partners that they will not leave them on their own with any other bue Flibbin. What is the quickest way of getting the five pairs of Flibbins safely to. . . .
In the following sum the letters A, B, C, D, E and F stand for six distinct digits. Find all the ways of replacing the letters with digits so that the arithmetic is correct.
You can work out the number someone else is thinking of as follows. Ask a friend to think of any natural number less than 100. Then ask them to tell you the remainders when this number is divided by. . . .
Baker, Cooper, Jones and Smith are four people whose occupations are teacher, welder, mechanic and programmer, but not necessarily in that order. What is each person’s occupation?
The nth term of a sequence is given by the formula n^3 + 11n . Find the first four terms of the sequence given by this formula and the first term of the sequence which is bigger than one million. . . .
Show that if you add 1 to the product of four consecutive numbers the answer is ALWAYS a perfect square.
You have twelve weights, one of which is different from the rest. Using just 3 weighings, can you identify which weight is the odd one out, and whether it is heavier or lighter than the rest?
How many pairs of numbers can you find that add up to a multiple of 11? Do you notice anything interesting about your results?
Powers of numbers behave in surprising ways. Take a look at some of these and try to explain why they are true.
Advent Calendar 2011 - a mathematical activity for each day during the run-up to Christmas.
A game for 2 players that can be played online. Players take it in turns to select a word from the 9 words given. The aim is to select all the occurrences of the same letter.
Consider the equation 1/a + 1/b + 1/c = 1 where a, b and c are natural numbers and 0 < a < b < c. Prove that there is only one set of values which satisfy this equation.
The first of five articles concentrating on whole number dynamics, ideas of general dynamical systems are introduced and seen in concrete cases.
Start with any whole number N, write N as a multiple of 10 plus a remainder R and produce a new whole number N'. Repeat. What happens?
In how many distinct ways can six islands be joined by bridges so that each island can be reached from every other island...
There are four children in a family, two girls, Kate and Sally, and two boys, Tom and Ben. How old are the children?
You have been given nine weights, one of which is slightly heavier than the rest. Can you work out which weight is heavier in just two weighings of the balance?
Find the largest integer which divides every member of the following sequence: 1^5-1, 2^5-2, 3^5-3, ... n^5-n.
Arrange the numbers 1 to 16 into a 4 by 4 array. Choose a number. Cross out the numbers on the same row and column. Repeat this process. Add up you four numbers. Why do they always add up to 34?
Six points are arranged in space so that no three are collinear. How many line segments can be formed by joining the points in pairs?
From a group of any 4 students in a class of 30, each has exchanged Christmas cards with the other three. Show that some students have exchanged cards with all the other students in the class. How. . . .
Which of these roads will satisfy a Munchkin builder?
Can you explain why a sequence of operations always gives you perfect squares?
Problem solving is at the heart of the NRICH site. All the problems give learners opportunities to learn, develop or use mathematical concepts and skills. Read here for more information.
Euler found four whole numbers such that the sum of any two of the numbers is a perfect square...
If a two digit number has its digits reversed and the smaller of the two numbers is subtracted from the larger, prove the difference can never be prime.
What are the missing numbers in the pyramids?
Some diagrammatic 'proofs' of algebraic identities and inequalities.
Imagine two identical cylindrical pipes meeting at right angles and think about the shape of the space which belongs to both pipes. Early Chinese mathematicians call this shape the mouhefanggai.
Can you discover whether this is a fair game?
In this 7-sandwich: 7 1 3 1 6 4 3 5 7 2 4 6 2 5 there are 7 numbers between the 7s, 6 between the 6s etc. The article shows which values of n can make n-sandwiches and which cannot.
An article which gives an account of some properties of magic squares.
Kyle and his teacher disagree about his test score - who is right?
Can you convince me of each of the following: If a square number is multiplied by a square number the product is ALWAYS a square number...
A composite number is one that is neither prime nor 1. Show that 10201 is composite in any base.
Clearly if a, b and c are the lengths of the sides of an equilateral triangle then a^2 + b^2 + c^2 = ab + bc + ca. Is the converse true?
Can you cross each of the seven bridges that join the north and south of the river to the two islands, once and once only, without retracing your steps?
A picture is made by joining five small quadrilaterals together to make a large quadrilateral. Is it possible to draw a similar picture if all the small quadrilaterals are cyclic?
ABCD is a square. P is the midpoint of AB and is joined to C. A line from D perpendicular to PC meets the line at the point Q. Prove AQ = AD.
This article discusses how every Pythagorean triple (a, b, c) can be illustrated by a square and an L shape within another square. You are invited to find some triples for yourself.
Some puzzles requiring no knowledge of knot theory, just a careful inspection of the patterns. A glimpse of the classification of knots and a little about prime knots, crossing numbers and. . . .
Caroline and James pick sets of five numbers. Charlie chooses three of them that add together to make a multiple of three. Can they stop him? | <urn:uuid:e922e8fd-8589-4d03-98c1-25b9ca98ed14> | 2.921875 | 1,674 | Content Listing | Science & Tech. | 76.623123 | 95,644,771 |
Mismatched feet may be a sign of population stress.
© Lens et al.
Asymmetric bodies fuel arguments over ecological risk.
Birds with one foot bigger than the other are showing signs of stress, say Belgian ecologists. The study backs the controversial idea that measuring body asymmetries could signal that a species is at risk.
Researchers at the University of Antwerp measured the feet of taita thrushes from three remaining pockets of their native forest in Kenya. Those from the most disturbed area showed eight times more difference between the size of their left and right feet than the least disturbed - a sign of future decline, they say1.
In general, the studies that find a correlation are the ones that get published; those that don’t, rarely make it into print. This issue has given ’fluctuating asymmetry’ a chequered history, with as many sceptics as believers.
Finding the mechanism underlying the disparity will be key to settling the debate. "We’re not at the stage that we understand enough about it and why in some cases it works and others it doesn’t," says conservation biologist Andrew Balmford at the University of Cambridge, UK.
Lens argues that the foot measure in thrushes reveals an indirect link between asymmetry and survival. It is an indicator of a male’s overall quality, he suggests - important to females, who choose the most symmetrical mates. Thus increased asymmetry may imply that a male is less fit. "People wrongly assume that because the differences are so small, the impact or biological relevance is also small," says Lens.
Many who have studied fluctuating asymmetry will not be convinced of its general utility until it can be proven under controlled situations. "When people have examined fluctuating asymmetry and stress in experimental lab conditions, the basic incontrovertible finding is that there is no consistent linkage," argues Andrew Pomiankowski, a geneticist at University College London.
Lens and his colleagues acknowledge that previous work has suffered from confounding measurement errors. But they claim to have developed new statistical methods that accurately separate variation caused by asymmetry from measurement error.
Pomiankowski agrees that for this particular trait in this species, Lens and his group may have found a real difference, but that it can’t be assumed to work elsewhere. It will have to be determined on a case by case study, says Pomiankowski - there is no universal trait that will indicate an individual’s fitness.
Asymmetry measures might be most useful if they could pick up insidious, hard-to-detect threats, suggests Balmford, such as the spread of disease, rather than stresses resulting from habitat decline. There are about 1,350 thrushes in the region studied by Lens, but the most degraded area has a declining population and the fewest individuals.
VIRGINIA GEWIN | © Nature News Service
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...
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"Deep-seafloor volcanism, which is sort of out of sight, out of mind, may have a long-term feedback into our whole climate system," says Maya Tolstoy, an associate professor at Lamont-Doherty Earth Observatory at Columbia University. "If we are going to protect Earth we have to understand how the planet functions as a whole."
Cyclical variations in Earth's tilt and orbit--occurring at 23,000-, 41,000- and 100,000-year intervals--are known to strongly influence our planet's long-term climate. They are associated with the coming and going of ice ages that also takes place about every 100,000 years.
In particular, changes in the roundness of Earth's orbit around the Sun unfold on approximately the same 100,000 year cycle as the planet's global swings between icy and temperate conditions. But, the variation in solar radiation reaching Earth due to temporarily larger and smaller distances between our planet and the Sun can't fully explain the magnitude of the climatic shifts.
The new research finds evidence in the profile of sea-floor elevation that volcanic activity at mid-ocean ridges, where molten rock emerges from Earth's interior and creates new planetary crust, coincides with these 100,000-year changes in Earth's orbit and climate. Given that volcanic eruptions release the climate-altering gas carbon-dioxide, significant emissions of the gas might take place during upswings of undersea volcanic activity, potentially affecting the climate at 100,000-year intervals.
"Generally, mid-ocean ridges are thought of as this tiny, not very significant contributor to the carbon cycle and that is true, but that's because they are thought of as a steady-state process. But, if they go through periods of significantly enhanced volcanism and significantly suppressed volcanism, then they may be more important than we thought," said Tolstoy, sole author of the new study accepted for publication in Geophysical Research Letters, a journal of the American Geophysical Union.
Tolstoy's study is complementary to new research published today in the journal Science that finds some glacial cycles are connected to the production of ocean crust.
Changes to the roundness of Earth's orbit, which alter the gravitational force on the planet from the Sun, may flex the planet's crust, intensifying volcanic activity when the already thin, undersea crust stretches out, the study explains. Changes in sea level from periodic melting and rebuilding of ice caps and glaciers could also contribute to a varying frequency of eruptions: When sea level is high, more water creates more pressure at the ocean bottom, which suppresses volcanism, and vice versa, when sea level declines again.
In her research, Tolstoy studied 10 present-day eruptions at mid-ocean ridges and the topography around one mid-ocean ridge where ancient volcanic eruptions had left traces. Because newly formed crust pushes outward from those ridges at a regular pace as it forms, the elevation of the sea floor, representing the buildup of new rock, provides a temporal record of how much outpouring of magma took place when.
From the recent eruptions and other researchers' seismic studies of them, Tolstoy finds that volcanic activity intensified when crust-compressing gravitational forces due to the Moon and Sun were low, underscoring that eruption rates are sensitive to forces of this type, which are also at play as the shape of Earth's orbit gradually changes.
As for the ancient eruptions and the topographic pattern they left behind, she finds that there were fewer or smaller eruptions coinciding with periods when there was less carbon dioxide in the atmosphere and when Earth's orbit was closer to being a perfect circle. Also, there were more eruptions during periods of more carbon dioxide in the atmosphere and Earth's orbit being more out-of-round. Tolstoy's analysis also shows a correspondence between periods of low sea level and high volcanism and the other way around.
The new findings suggest that changes in both sea level and the shape of Earth's orbit may influence the rate of eruption at these mid-ocean ridges. These changes in seafloor volcanic activity may, in turn, feed back into climate cycles, possibly contributing to glacial cycles, the abrupt end of ice ages and the dominance of the 100,000-year climate cycle, according to the new study.
This research does not put a number on how much carbon dioxide could be released by these undersea eruptions. However, the study suggests that these volcanic eruptions could be acting as a "climatic valve" that causes the flow of greenhouse gases to fluctuate, and that models of the Earth's climate system might be rendered more accurate by including them.
These findings could change the way scientists think about how to model Earth's climate's past behavior and could influence how they predict the planet's future climate, Tolstoy said.
The Daily Galaxy via American Geophysical Union
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Back-End Process Of Mobile App Development
Mobile app developers stand to gain a critical business advantage by designing an efficient mobile app particularly one that easily enables your end users to tap into your databases with adequate ease and security. It’s all about building a mobile app with a great UX. But before you can deliver such a rich and powerful experience, it is good to know that there are quite a lot of things that must be done.
Also known as Content Management System (CMS), the back office or back-end is the invisible part of the app (i.e. to most users, it remains hidden), however, it is highly visible to the admin or app developers. While the back end is concerned with the happenings on the server — it is colloquially referred to as the “nuts and bolts” of the app.
The back-end of any app is designed to;
- Provide access to the required information on the app.
- Collect and interpret the information for users
- Return back the information to the requester in a new state.
This is where the implementation of business logic and data handling are found. The backend also presents meaningful integration with their party systems. It is important to know that every data displayed in the front end resides on a hosting server located in the back end.
When it comes to the development of an app’s backend, there are many technologies that come to play. It is basically aimed at creating a server that can efficiently and purposefully communicate with the front end. Note that this may involve the use of several technologies, such as Python, Ruby, LAMP (Linux, Apache, MySQL and PHP), Java, .Net, to mention but a few.
The Use of Databases
The need of a database is required for the storage and arrangement of data. After writing a server to hold your user data, you need a database to store them up. MongoDB, PostgreSQL, and MySQL are the most common types of databases used for app development.
In order to successfully query the database for your required data, you need relevant knowledge on database development which is primarily concerned with the use of a query language (such as SQL) and the creation of relational or non-relational table structures.
It is also worthy to note that there will be no proper communication between the mobile app and a server if some sort of communication protocol such as SOAP (Simple Object Access Protocol) and REST (Representational State Transfer) is not established.
Application Programming Interfaces (APIs) refer to the tools employed in the process of mobile app development to transport information produced at the back-end to the front-end of the app. Without the APIs, the front-end will have no data to translate. App users only understand visually converted elements such as text, menus, pictures, buttons etc. Except the data has been brought through the API, this cannot be made possible.
The back-end is the foundation of any app. No matter how innovative and beautifully crafted an app is, if the foundation is weak, the app is definitely going to be a failure. If you must create a good front-end experience then you must be ready to spend time and resources working on how to establish a well-built back-end. No user will want to keep an inefficient app on their device; they are always quick to uninstall them. | <urn:uuid:10479113-ea09-4ba9-bf63-48b37499f76b> | 2.6875 | 694 | Tutorial | Software Dev. | 43.9125 | 95,644,788 |
A combination of X-ray diffraction and computational techniques can determine unknown crystal structures in powder mixtures
The characterization of individual components in an unknown crystalline powder mixture is a challenge that has eluded scientists for many years. Now, A*STAR researchers have for the first time invented a methodology to accurately determine the crystal structures present in such mixtures1.
A new method that combines X-ray diffraction with computational analysis can be used to measure mixtures of unknown solids and identify their individual components.
© 2014 A*STAR Institute of Chemical and Engineering Sciences
Powder X-ray diffraction (PXRD) is a powerful tool used to determine the structure of crystalline solids. Every solid has its own unique crystal structure which, when hit by X-rays, produces a unique diffraction pattern — a ‘fingerprint’ from which the solid can then be identified and characterized through computational analysis.
However, traditional PXRD works best with pure single-component powders; mixed powders of unknown solids are far more difficult to analyze because the diffraction patterns overlap and are difficult to separate. Another complication is that individual solids can produce slightly different diffraction patterns depending on how the crystals are shaped and orientated in the powder samples.
Marc Garland and co-workers at the A*STAR Institute of Chemical and Engineering Sciences in Singapore have developed a new methodology, the PXRD-BTEM-Rietveld method, which combines two existing techniques to determine the individual crystal structures in a powder mixture.
“Many analytical problems in the chemical sciences involve mixtures of unknown solids,” explains Garland. “The extension of PXRD analysis to these mixtures opens up a myriad of new possibilities for the experimentalist because a purified single-component sample is no longer needed.”
First, Garland and his team used PXRD to obtain diffraction datasets from pre-prepared mixtures of several different powders. They then used their own algorithm, called band-target entropy minimization (BTEM), to sift through the entire dataset, looking for the simplest underlying patterns and to untangle overlapping diffraction patterns.
“BTEM is a blind separation technique,” explains Garland. “By searching for the simplest patterns — those with the smoothest profiles and the least signal disorder — we obtain accurate estimates of each pure component’s diffraction pattern.”
Garland and his team then used computational structure determination, including so-called Rietveld refinement, to obtain the crystal structures for each solid. This allowed the researchers to characterize the unknown components in the mixtures.
“One example of an application for our new technique could be investigating polymorphism in pharmaceuticals,” says Garland. “Each polymorphic pharmaceutical solid has a unique diffraction pattern resulting from its crystal structure, and it is incredibly important to the pharmaceutical industry to identify these from mixtures.”
The researchers plan to further refine their methodology, and hope to eliminate the problem of measuring irregularities due to crystal orientation.
Schreyer, M., Guo, L., Thirunahari, S., Gao, F. & Garland, M. Simultaneous determination of several crystal structures from powder mixtures: The combination of powder X-ray diffraction, band-target entropy minimization and Rietveld methods. Journal of Applied Crystallography 47, 659–667 (2014).
A*STAR Research | ResearchSEA
What happens when we heat the atomic lattice of a magnet all of a sudden?
17.07.2018 | 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
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Fire in the Tropics October 21, 2010. Fire in the tropics: natural or human tool?. Natural disturbance in some tropical and subtropical ecosystems, but… Currently fire is largely a “ land treatment tool ” in the tropics:
How do fire regimes in these ecosystems compare with temperate ecosystems that we have studied this semester?
Carribbean Pine in Honduras
Conversion to pastureEscaped fires!
Mexican Tropical Cloud Forests
Explain how Amazon fire dynamics and climate change are related to each other on:
- local scales, and
- regional scales | <urn:uuid:a117e706-1aa2-4b52-8794-6531907a9a3a> | 2.703125 | 122 | Content Listing | Science & Tech. | 21.805277 | 95,644,804 |
Anatase, one of three minerals composed of titanium dioxide (TiO2), the other two being rutile and brookite. It is found as hard, brilliant crystals of tetragonal symmetry and various colours in veins in igneous and metamorphic rocks and commonly in placer deposits of detritus. Notable vein deposits exist in many regions of the Alps; placer deposits are common in Minas Gerais and Bahia, Braz. Much anatase is formed by weathering of titanite, and it is itself altered to rutile; rutile paramorphs (replacements having the same outward shape) after anatase are common in the detrital deposits of Brazil and the Sanarka region of the Urals. For detailed physical properties, see oxide mineral (table).
Learn More in these related Britannica articles:
Oxide mineral, any naturally occurring inorganic compound with a structure based on close-packed oxygen atoms in which smaller, positively charged metal or other ions occur in interstices. Oxides are distinguished from other oxygen-bearing compounds such as the silicates, borates, and carbonates, which have a readily definable group containing oxygen atoms…
surface coating: White pigmentsAnother crystal form of TiO2, anatase, is sometimes used in coatings, but its lower index of refraction (2.55) makes it a less optically efficient pigment. Furthermore, surface-treated TiO2 in its rutile form yields coatings that are more durable to exterior exposure than are equivalent anatase pigments. TiO2 pigments are used…
RutileRutile, the most abundant of three naturally occurring forms of titanium dioxide (TiO2; see also anatase; brookite). It forms red to reddish brown, hard, brilliant metallic, slender crystals, often completely surrounded by other minerals. Rutile is a commercially important titanium mineral,…
EarthEarth, third planet from the Sun and the fifth in the solar system in terms of size and mass. Its single most-outstanding feature is that its near-surface environments are the only places in the universe known to harbour life. It is designated by the symbol ♁. Earth’s name in English, the…
More About Anatase1 reference found in Britannica articles | <urn:uuid:b7494f2b-4823-4a73-bb9f-25e7ed67fe9c> | 3.703125 | 481 | Knowledge Article | Science & Tech. | 15.918415 | 95,644,825 |
Physics Question #9011
kyler, a 15 year old from the Internet asks on December 18, 2013,
If I were to tie a rope or something like that to the moon and have it dangle far enough toward the earth so I can reach it on the ground, would I be able to hold on to the rope and travel around the earth very fast because the moon is rotating around the earth?
viewed 1000 times
answered on December 20, 2013
First let's pretend that the Moon and the Earth are both at rest with respect to each other. Then the rope would feel a net attraction towards the Moon until it was about 1/4 of the way to the Earth; then it would feel no net gravity; then as it got closer to the Earth it would be attracted more and more in that direction. If it were stretched all the way from the Moon to the Earth, the net force on it would be towards the Earth (because the Earth is heavier) so you'd better make sure it's tied tightly to the Moon.
Now, no ordinary rope would be able to support its own weight; in fact I doubt that even carbon nanotubes (the strongest stuff we know, if I remember correctly) would be strong enough for THAT application. But even if it could, there's another problem.
The Moon and the Earth are NOT at rest, either by themselves or with respect to each other. The Moon is in orbit around the Earth; it goes around once every 28 days or so. It's moving pretty fast 'way out there on the end of the rope, just exactly fast enough that it "falls" toward the Earth at just the right acceleration to keep going in a circle so it never gets much closer or further away. The Moon end of the rope would also be in "free fall" with respect to the Earth, so the Earth's share of the tension on the rope would be zero there.
Note that it would be pretty hard to get the rope stretched between the Earth and the Moon in the first place, because of that motion. Perhaps if you stretched the rope out straight by itself in a place where the Earth and Moon would "run into it" and then grabbed the ends... but you'd put an enormous strain on the rope to get it moving at the speed of the Moon around the Earth, and it would probably just break. But let's imagine that you've solved that problem. There is an even worse one.
The Earth is spinning on its axis, once a day. Where would you attach the rope? Maybe at the North pole? Be sure to have a good bearing! In the end, the rope would not be moving with respect to the Earth, except to rotate about the Earth's axis. (Actually the rope would rotate 1/28 as fast as the Earth, which would be rotating under it.) So you wouldn't move with respect to the Earth's surface until you climbed up the rope towards the Moon. At that point you'd feel a small pull sideways (called a Coriolis force) depending on how fast you climbed, and your apparent weight would decrease gradually as you got higher up, until you got up to the altitude of "geosynchronous orbit" ('way above the atmosphere, so be sure to wear a space suit), at which point you'd feel weightless, because you'd be in orbit!
That part would be pretty cool. Forget the Moon; you can just attach a big rock to the rope a little above geosynchronous orbit and use this as a "space elevator" to get into orbit without rockets! You should read Arthur C. Clarke's "Fountains of Paradise"
to learn more about this possibility.
Add to or comment on this answer using the form below.
Note: All submissions are moderated prior to posting.
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A brown dwarf over 100 light years away from the Sun has been discovered using a new citizen-science tool that helps astronomers pinpoint new worlds lurking in the outer reaches of our solar system. Just six days after the launch of the Backyard Worlds: Planet 9 website in February, four different users alerted the science team to the curious object, whose presence has since
been confirmed via an infrared telescope.
"I was so proud of our volunteers as I saw the data on this new cold world coming in," said Jackie Faherty, a senior scientist at the American Museum of Natural Historyand one of Backyard World's researchers. "It was a feel-good moment for science," said Faherty. The Backyard Worlds project lets anyone with a computer and an internet connection flip through images taken by NASA's Wide Field Infrared Survey Explorer (WISE) spacecraft.
If an object is close enough to Earth, it will appear to "jump" when multiple images taken of the same spot in the sky a few years apart are compared. The goal for Backyard Worlds volunteers - of which there are more than 37,000 - is to flag the moving objects they see in these digital flipbooks for further investigation by the science team. So far, volunteers have classified more than 4
Days after the Backyard Worlds website debuted on February 15, Bob Fletcher, a science teacher in Australia, identified a very faint object moving across the WISE images. It was soon also flagged by three other citizen scientists from Russia, Serbia and the US. After some initial investigation by the research team, which originally called the object "Bob's dwarf," Faherty was awarded time on NASA's Infrared Telescope Facility in Hawaii, where she confirmed that it was a previously unknown brown dwarf just a few hundred degrees warmer than Jupiter.
The authors of the research published in the Astrophysical Journal Letters said that sky surveys had missed this object because it is too faint. Brown dwarfs, sometimes called "failed stars," are spread throughout the Milky Way. They lack enough mass to sustain nuclear fusion but they are hot enough to glow in the infrared range of the light spectrum. "Brown dwarfs are strikingly similar to Jupiter so we study their atmospheres in order to look at what weather on other worlds might look like," said Jonathan Gagne, a Backyard Worlds team member from the Carnegie Institution for Science.
Although the Backyard Worlds research team hopes to find the infamous Planet 9 hiding in our own solar system, these brown dwarfs are also exciting discoveries. "It is possible that there is a cold world closer than what we believe to be the closest star to the Sun. Given enough time, I think our volunteers are going help to complete the map of our solar neighborhood," Faherty said. | <urn:uuid:0cb89e3f-601c-4f99-8ad0-0be11605b0ef> | 3.78125 | 557 | News Article | Science & Tech. | 42.482913 | 95,644,842 |
Heidelberg chemists succeed in isolating carbon-gold compound of “amazing stability”
With a chemical “trick”, scientists at Heidelberg University have succeeded in isolating a stable gold carbene complex. Chemist Prof. Dr. Bernd F. Straub and his team are the first to have created the basis for directly examining the otherwise unstable gold-carbon double bond. Prof. Straub explains that highly reactive gold carbene molecules play an important role in landmark catalysing processes taking place at high speed. The research findings have been published in the German and the international edition of „Angewandte Chemie“, a journal on applied and fundamental chemistry.
Chemical reactions can be accelerated with the aid of catalysts; consequently materials and pharmaceuticals can be manufactured from the raw materials of nature. The study of gold compounds in catalytic processes has proved particularly intensive and successful, according to Prof. Straub. “In numerous scientific studies in the last ten years, experts have been proposing gold carbenes as essential short-lived intermediates in catalytic reactions,” the Heidelberg researcher explains. However, with their high reactivity they escape detailed study: hardly has a gold carbene fragment consisting of the elements gold and carbon emerged – Au for aurum and C for carbon – when it continues to react.
In order to first create a stable complex and isolate a gold carbene structure for research, the two elements were “lured into a cage like a hungry tiger with a bait,” says Matthias Hussong, who is working on his doctoral dissertation in Prof. Straub’s team. The researchers first shielded the gold and carbon from its environment by surrounding them with low-reactive, space-filling chemical groups. Then the two elements were bonded in a carefully planned step – and so the Au=C fragment was “caught” in the gold carbene complex.
The chemists were able to impart “an amazing stability” to the gold carbene, says Prof. Straub – and at the same time to make it literally visible. “Almost all gold complexes are colourless, while the ‘stable’ gold carbene is emerald green,” states the scientist, who heads a research group at Heidelberg University‘s Institute of Organic Chemistry. Further Heidelberg studies showed that gold in its compounds is more than a “soft proton”, as the chemical behaviour of gold had been described to date.
If the gold fragment is replaced by a “real” proton, e.g. the nucleus of hydrogen, the lightest element, this analogous protonated carbene displays a reddish purple colour. “The gold in the gold carbene complex behaves differently from a proton – that is very clear to the eye,” states Prof. Straub. He and his team are now continuing to explore the understanding of gold catalysis, with the aim of using these findings to make catalytic processes more efficient.
Hussong, M. W., Rominger, F., Krämer, P. und Straub, B. F.: Isolierung eines nicht-Heteroatom-stabilisierten Goldcarbens. Angew. Chem. (online veröffentlicht am 20. Juni 2014), doi: 10.1002/ange.201404032
Hussong, M. W., Rominger, F., Krämer, P. and Straub, B. F.: Isolation of a Non-Heteroatom-Stabilized Gold–Carbene Complex. Angew. Chem. Int. Ed. (published online 20 June 2014), doi: 10.1002/anie.201404032
Prof. Dr. Bernd F. Straub
Institute of Organic Chemistry
Phone: +49 6221 54-6239
Communications and Marketing
Press Office, phone: +49 6221 54-2311
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Scientists uncover the role of a protein in production & survival of myelin-forming cells
19.07.2018 | Advanced Science Research Center, GC/CUNY
NYSCF researchers develop novel bioengineering technique for personalized bone grafts
18.07.2018 | New York Stem Cell 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....
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Edited By: TL Crisman, LJ Chapman, CA Chapman and LS Kaufman
514 pages, 54 b/w figs, 59 tabs
Provides a continent-wide perspective on environmental problems in the context of a rapidly expanding human population.
Deforestation, exotic species, wetland degradation, hydro-development projects, fisheries exploitation, and pollution all pose serious threats to African lakes, rivers, and wetlands.... This book provides a synthesis of the state of our knowledge of selected ecosystems in Africa and indicates the desperate need for sustained, intensive, and extensive research into the workings of these understudied systems. - Patrick Osborne, International Center for Tropical Ecology; "An important asset of this work is the integration of the freshwater resources into the complex fabric of social structures of the many nations that utilize these resources." - Robert Wetzel, University of North Carolina
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Here is what I would like some comments on:
brief overview of the nature and importance of light and other electromagnetic waves.
How stars fit in the hierarchy of the universe
characteristics of stars
Processes by which stars live and die
how the materials are recycled and how this process might be related to the structure of the Milky Way Galaxy and to the origin of the universe.
Need to consider these facts in describing the life cycle of stars:
Stars seem unchanging, but they are not. Stars are born from the interstellar medium, become main sequence stars, use up sources of energy, and then ultimately die. During this time, the star can change dramatically. Then its ultimate fate depends on its mass.
The solution contains two attached files. See the attached files.
Stars seems to be very small because of its large distance from us. Star has many different stages in its life cycle.
In the spaces between stars, there exists a large amount of gas and dust. In course of time, these clouds of gas and dust
compressed under their own internal gravitational fields. The temperature of these clouds of gas and dust increases and the nuclear
reaction occurred when it reaches the enough temperature for this reaction. Thus the new stars are born from these clouds
The gravitational attraction towards the centre of the star due to its mass is balanced by the outward pressure due
to the heat generated by the nuclear reaction. Thus the stable configuration is formed. The nuclear energy of the star is due
to the conversion of hydrogen into helium.
There are three different ways that a star ends its nuclear fuels.If the star is more massive than the Sun, it goes another
phase of reaction by converting helium into elements of higher atomic numbers. If the star is massive as the Sun, ...
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By: Ronaldo Barthem and Michael Goulding
241 pages, 200 colour photos and illus
The Amazon has the richest freshwater fish fauna in the world, and its evolution is closely linked to the rainforest and the vast floating meadows of the floodplains. Fisheries illustrate the urgent need to look at the Amazon rainforest and its rivers as an ecosystem in view of current environmental changes. Proper management of the fisheries requires protecting flooded forests, floating meadows, headwater spawning areas, and other critical habitats.
With over 200 colour photos and illustrations, this book richly illustrates how the fishes and fisheries are part of the river-and-rainforest ecosystem and what needs to be done for their conservation.
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Image Courtesy of: Andrew Gillis
Latest analysis shows that human limbs share a genetic programme with the gills of cartilaginous fishes such as sharks and skates, providing evidence to support a century-old theory on the origin of limbs that had been widely discounted.
An idea first proposed 138 years ago that limbs evolved from gills, which has been widely discredited due to lack of supporting fossil evidence, may prove correct after all—and the clue is in a gene named for everyone's favourite blue hedgehog.
Unlike other fishes, cartilaginous fishes such as sharks, skates and rays have a series of skin flaps that protect their gills. These flaps are supported by arches of cartilage, with finger-like appendages called branchial rays attached.
Image Courtesy of: Andrew GillisIn 1878, influential German anatomist Karl Gegenbaur presented the theory that paired fins and eventually limbs evolved from a structure resembling the gill arch of cartilaginous fishes. However, nothing in the fossil record has ever been discovered to support this.
Now, researchers have reinvestigated Gegenbaur's ideas using the latest genetic techniques on embryos of the little skate—a fish from the very group that first inspired the controversial theory over a century ago—and found striking similarities between the genetic mechanism used in the development of its gill arches and those in human limbs.
Scientists say it comes down to a critical gene in limb development called 'Sonic hedgehog', named for the videogame character by a research team at Harvard Medical School.
The new research shows that the functions of the Sonic hedgehog gene in human limb development, dictating the identity of each finger and maintaining growth of the limb skeleton, are mirrored in the development of the branchial rays in skate embryos. The findings are published today in the journal Development.
Dr Andrew Gillis, from the University of Cambridge's Department of Zoology and the Marine Biological Laboratory, who led the research, says that it shows aspects of Gegenbaur's theory may in fact be correct, and provides greater understanding of the origin of jawed vertebrates—the group of animals that includes humans.
"Gegenbaur looked at the way that these branchial rays connect to the gill arches and noticed that it looks very similar to the way that the fin and limb skeleton articulates with the shoulder," says Gillis. "The branchial rays extend like a series of fingers down the side of a shark gill arch."
"The fact that the Sonic hedgehog gene performs the same two functions in the development of gill arches and branchial rays in skate embryos as it does in the development of limbs in mammal embryos may help explain how Gegenbaur arrived at his controversial theory on the origin of fins and limbs."
In mammal embryos, the Sonic hedgehog gene sets up the axis of the limb in the early stages of development. "In a hand, for instance, Sonic hedgehog tells the limb which side will be the thumb and which side will be the pinky finger," explains Gillis. In the later stages of development, Sonic hedgehog maintains outgrowth so that the limb grows to its full size.
To test whether the gene functions in the same way in skate embryos, Gillis and his colleagues inhibited Sonic hedgehog at different points during their development.
They found that if Sonic hedgehog was interrupted early in development, the branchial rays formed on the wrong side of the gill arch. If Sonic hedgehog was interrupted later in development, then fewer branchial rays formed but the ones that did grow, grew on the correct side of the gill arch—showing that the gene works in a remarkably similar way here as in the development of limbs.
"Taken to the extreme, these experiments could be interpreted as evidence that limbs share a genetic programme with gill arches because fins and limbs evolved by transformation of a gill arch in an ancestral vertebrate, as proposed by Gegenbaur," says Gillis. "However, it could also be that these structures evolved separately, but re-used the same pre-existing genetic programme. Without fossil evidence this remains a bit of a mystery—there is a gap in the fossil record between species with no fins and then suddenly species with paired fins—so we can't really be sure yet how paired appendages evolved."
"Either way this is a fascinating discovery, because it provides evidence for a fundamental evolutionary link between branchial rays and limbs," says Gillis. "While palaeontologists look for fossils to try to reconstruct the evolutionary history of anatomy, we are effectively trying to reconstruct the evolutionary history of genetic programmes that control the development of anatomy."
Paired appendages, such as arms and hands in humans, are one of the key anatomical features that distinguish jawed vertebrates from other groups. "There is a lot of interest in trying to understand the origins of jawed vertebrates, and the origins of novel features like fins and limbs," says Gillis.
"What we are learning is that many novel features may not have arisen suddenly from scratch, but rather by tweaking and re-using a relatively small number of ancient developmental programmes."
Gillis and his colleagues are further testing Gegenbaur's theory by comparing the function of more genes involved the development of skates' unusual gills and mammalian limbs.
"Previous studies haven't found compelling developmental genetic similarities between gill arch derivatives and paired appendages—but these studies were done in animals like mice and zebrafish, which don't have branchial rays," says Gillis.
"It is useful to study cartilaginous fishes, not only because they were the group that first inspired Gegenbaur's theory, but also because they have a lot of unique features that other fishes don't—and we are finding that we can learn a lot about evolution from these unique features."
"Many researchers look at mutant mice or fruit flies to understand the genetic control of anatomy. Our approach is to study and compare the diverse anatomical forms that can be found in nature, in order to gain insight into the evolution of the vertebrate body."
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12 July 2018
New low-cost catalyst helps generate hydrogen fuel
Published online 16 September 2015
Discovery of a cheap metal-based catalyst may pave the way for hydrogen-fuel-based economy.
Hydrogen, touted to be the cleanest fuel, can reduce the atmospheric levels of carbon dioxide. However, existing techniques employ expensive metals such as platinum to generate hydrogen from water.
A catalyst made from cobalt, a metal much cheaper than platinum, and common elements such as phosphorus and sulfur, can efficiently generate hydrogen from water by using electricity and sunlight. Chemically known as pyrite-type cobalt phosphosulfide, this catalyst is potentially useful for manufacturing water-splitting electrolytic and solar-driven photoelectrolysis cells1.
Using the catalyst, Song Jin and his colleagues from US-based University of Wisconsin–Madison prepared films and nanowires on graphite disk and nanoplates on carbon fibre paper.
In electrochemical studies, the films, the nanowires and the nanoplates generated hydrogen from water at very low turn-on potentials. When it came to splitting water, the films, the nanowires and the nanoplates performed better than the previously reported catalysts such as cobalt disulfide and cobalt phosphides.
Teaming up with Jr-Hau He and his colleagues from King Abdullah University of Science and Technology (KAUST), the researchers then found that the catalyst could generate hydrogen from water by harnessing sunlight.
“The catalytic efficiency of the new catalyst is very close to that of the platinum, suggesting its potential for developing electrolytic or solar-driven water-splitting cells,” says Jin.
Cabán-Acevedo, Miguel. et al. Efficient hydrogen evolution catalysis using ternary pyrite-type cobalt phosphosulphide. Nat. Mater. http://dx.doi.org/10.1038/NMAT4410 (2015). | <urn:uuid:dbd62bf7-996d-4284-842f-f463a978cdf7> | 3.484375 | 411 | Truncated | Science & Tech. | 25.712938 | 95,644,885 |
Authors: Alexander G. Kyriakos
The most advanced theory of gravitation is so far Einstein's general relativity theory. Some of its drawbacks are the source of attempts to construct a new theory of gravitation. The main drawback of general relativity theory is its incompatibility with the modern quantum theory of elementary particles, which does not allow to create a unified theory of matter. In the general relativity the cause of the gravitational field is the curvature of space-time, which is not a material object. The question of, how non-material space-time can cause a material gravitational field is still here unanswered. Different subdisciplines of classical physics generated different ways of approaching the problem of gravitation. The emergence of special relativity further increased the number of possible approaches and created new requirements that all approaches had to come to terms with. In this book we will survey various alternative approaches to the problem of gravitation pursued around the turn of the last century and try to assess their potential for integrating the contemporary knowledge of gravitation. Here different contributions are made to the discussion about the fundamentals of different approaches to gravitation and their advantages and drawbacks.
Comments: 104 Pages.
[v1] 2016-11-01 06:14:41
Unique-IP document downloads: 449 times
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A View from Emerging Technology from the arXiv
Counterintuitive Defocusing Technique Produces 3-D Microscope Images
By defocusing a microscope, biologists have developed a simple technique that produces three-dimensional images of red blood cells.
One of the great inventions in history was the development of the microscope. The ability to see the enormous variety of life and patterns on such a tiny scale changed our understanding of the world and our relationship to it.
Since then microscopists have dramatically improved their instruments so that they record not only with visible light but other wavelengths and even with other recording media entirely such as electrons and neutrons and so on.
One of the most difficult challenges, however, is determining the three-dimensional structure of small objects. Healthy red blood cells, for example, have a famous doughnut-shaped structure and changes to this structure are an important indicator of various diseases and conditions.
These shapes are straightforward to see but determining their entire 3-D structure with a resolution of a few hundred nanometers is tricky; not least because red blood cells are largely transparent and difficult to see with ordinary bright field microscopy.
Today, Paula Roma and pals at the Federal University of Minas Gerais in Brazil reveal a new and relatively simple technique for determining the entire 3-D structure of red blood cells based on the counterintuitive technique of defocusing.
Biologists have long recognized the limitations of bright field microscopy with biological samples because many are largely transparent. (Bright field microscopy is the ordinary microscope technique that most people come across in high school.)
Light shines onto or through the sample revealing anything that strongly absorbs or scatters light.
The trouble is that anything that is transparent is more or less invisible because light passes straight through it. And unfortunately, many biological samples fall into this category—including red blood cells which are largely transparent.
One way round this is to defocus the image slightly. Since the red blood cells have a refractive index, they bend the light that passes through it. This bending introduces a phase change in the light.
This phase change makes it easier to separate this light from light that has not passed through cell. And by doing this, the red blood cells become darker and easier to see.
That allows more detailed analysis of the cells. By measuring the changes in intensity that this process introduces, it is possible to work out the shape of the surface generating the phase changes. So that gives a three dimensional image of the upper surface of the cell.
Now Roma and co say it’s possible to go further. They show that by taking two images of the cell, both defocused by different amounts, it is possible to work out the shape of the cell’s bottom surface as well. In other words, this weird kind of defocused stereo image gives you the 3-D shape of the entire cell.
The results are impressive. The technique works with ordinary white light, although this has to be filtered to remove the red wavelengths that red blood cells might absorb.
To get two images of the same cell, Roma and co use a beam splitter to send light to two cameras that are both defocused by different amounts. The results can then be processed using a straightforward algorithm to produce 3-D images of the cells
To test the idea, Roma and co placed red blood cells in various concentrations of salt solutions to make them swell. They recorded images of 25 cells and processed the results, which are shown above.
They say the images have a resolution of within 300 nanometers, significantly better than is possible with similar techniques. In particular, they show how the cells adhere to the surface they are attached to.
The setup is also relatively straightforward. “The technique could be easily adopted by nonspecialists,” they say.
That’s an interesting result that shows how fascinating low cost advances can still be made in microscopy.
Ref: http://arxiv.org/abs/1404.2968 : Total 3D Imaging Of Phase Objects Using Defocusing Microscopy: Application o Red Blood Cells
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Now, in an ambitious initiative scientists want to apply this concept to life by using DNA - nature's unique barcode of every species of animal, plant and microbe - to create a vast library of every living organism on the planet. Such a global DNA barcode database would prove invaluable in numerous ways, from identifying new species of organism and monitoring biodiversity to detecting fraud.
The ECBoL initiative aims to establish a Network of European Leading Laboratories (NELL) among major biodiversity resource centres of Europe. This network will have the capacity to generate DNA barcodes of species at an industrial scale, for identifying life on earth. Once established, the consortium has a goal to initially barcode 1M specimens, representing 100K species within 5 years. Further initiatives will be launched to expand the barcode database in an attempt to represent all known and as yet unknown life on Earth.
The 'barcodes' in living organisms are short sequences of genetic material that are unique to that organism. In animals, for example, a particular gene sequence in a structure in the cell called the mitochondrion has been shown to be unique to any given species. Similar sequences have been found for plants, and scientists are actively searching for barcode genes in bacteria, fungi and other micro-organisms.
It's essential that such an initiative is international in scope, and at this year's EuroBioForum meeting in Strasbourg in September, Professor Pedro Crous will be putting the case for Europe's involvement in the International Barcode of Life initiative.
"DNA barcoding will allow us to get a better understanding of life and a better appreciation of life," says Crous, who is director of the CBS Fungal Biodiversity Centre in Utrecht, The Netherlands.
The key advantage of DNA barcoding over traditional taxonomy to identify organisms is the potential for its great speed and accuracy. "Conventionally organisms are identified largely based on aspects such as their size, colour and unique morphological features," says Crous. "This gives rise to a situation where many species can be identified only by taxonomic experts, who are few and far between. This can make it difficult to identify known species as well as new ones. DNA barcoding would solve all this."
The concept is simple. A sample of the specimen is processed to produce the barcode. This is then matched against a library of known barcodes and in this way the specimen is identified.
"So if a shipment of exotic animals arrives at the customs point, you can determine very quickly if it contains endangered species or not and apprehend the involved importers," Crous says. "You can also answer a whole range of complex ecological and biodiversity questions."
To do this, the barcode database must first be constructed. The International Barcode of Life initiative was proposed by Canadian scientists and is seeking to raise 150 million Canadian dollars (just under 100 million euros) to barcode 500,000 species over the next five years. The logistics will inevitably be complex, so the initiative is proposing a series of central and regional 'nodes' to fund and coordinate the activity across the world. Over the years it is hoped that every species - several million - will eventually be barcoded.
"Europe will be a central node, and to qualify for this it is necessary to raise 25 million dollars in Europe," Crous says. "Europe needs to play a central role in this initiative. We have amazing collections in museums and herbaria that have been gathered over the past centuries - the lion's share of all the species known on Earth are represented in European collections. We also have a strong tradition of taxonomy, so we are in a uniquely powerful position to make a real impact in this field."
At the EuroBioForum meeting Crous will put forward proposals for a Network of European Leading Laboratories (NELL) to undertake most of the barcoding work. "At the moment we have eight or nine European countries with co-ordinators committed to this proposal" Crous says. "What we want to achieve at the EuroBioFund meeting is to get commitment from industry and governments that support biodiversity research to commit to this European barcoding campaign."
As technology develops, barcoding will become increasingly simple and widespread, Crous predicts. "One of the ultimate goals is to develop a hand-held DNA barcoder," Crous says. "This sounds very futuristic but is not as far-fetched as it might seem. Already people have portable technology for gene sequencing. There are wireless technologies that would be able to send the barcode data to a central database for matching and receive the result. What is still required is miniaturisation of the whole platform - the entire sample preparation. But various groups are working on this."
A hand-held system would allow people to carry out instant identification of specimens in the field - in a rain forest, for example, or, closer to home, in a hospital where microbiologists need to identify pathogenic organisms. For instance, an increasing numbers of immuno-suppressed patients are developing infections with organisms that were not previously known as pathogens. Fast and reliable identification of novel diseases can save those patients lives.
"Barcoding is the future," Crous concludes. "It would be a sin if Europe, with its rich collections and its unique expertise in taxonomy, does not play its part."
Scientists uncover the role of a protein in production & survival of myelin-forming cells
19.07.2018 | Advanced Science Research Center, GC/CUNY
NYSCF researchers develop novel bioengineering technique for personalized bone grafts
18.07.2018 | New York Stem Cell 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
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Partial E1 envelope glycoprotein gene sequences and complete structural polyprotein sequences were used to compare divergence and construct phylogenetic trees for the genus Alphavirus. Tree topologies indicated that the mosquito-borne alphaviruses could have arisen in either the Old or the New World, with at least two transoceanic introductions to account for their current distribution. The time frame for alphavirus diversification could not be estimated because maximum-likelihood analyses indicated that the nucleotide substitution rate varies considerably across sites within the genome. While most trees showed evolutionary relationships consistent with current antigenic complexes and species, several changes to the current classification are proposed. The recently identified fish alphaviruses salmon pancreas disease virus and sleeping disease virus appear to be variants or subtypes of a new alphavirus species. Southern elephant seal virus is also a new alphavirus distantly related to all of the others analyzed. Tonate virus and Venezuelan equine encephalitis virus strain 78V3531 also appear to be distinct alphavirus species based on genetic, antigenic, and ecological criteria. Trocara virus, isolated from mosquitoes in Brazil and Peru, also represents a new species and probably a new alphavirus complex.
Mendeley saves you time finding and organizing research
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Researchers have manufactured microscopic versions of the cocoons spun by silkworms, which could be used to store sensitive proteins and other molecules for a wide range of uses
Microscopic versions of the cocoons spun by silkworms have been manufactured by a team of researchers. The tiny capsules, which are invisible to the naked eye, can protect sensitive molecular materials, and could prove a significant technology in areas including food science, biotechnology and medicine.
The capsules were made at the University of Cambridge using a specially-developed microengineering process. The process mimics on the microscale the way in which Bombyx mori silkworms spin the cocoons from which natural silk is harvested. The resulting micron-scale capsules comprise a solid and tough shell of silk nano-fibrils that surround and protect a centre of liquid cargo, and are more than a thousand times smaller than those created by silkworms.
Writing in the journal Nature Communications, the team suggest that these "micrococoons" are a potential solution to a common technological problem: How to protect sensitive molecules that have potential health or nutritional benefits, but can easily degrade and lose these favourable qualities during storage or processing.
The study argues that sealing such molecules in a protective layer of silk could be the answer, and that silk micrococoons that are far too small to see (or taste) could be used to house tiny particles of beneficial molecular "cargo" in various products, such as cosmetics and food.
The same technology could also be used in pharmaceuticals to treat a wide range of severe and debilitating illnesses. In the study, the researchers successfully showed that silk micrococoons can increase the stability and lifetime of an antibody that acts on a protein implicated in neurodegenerative diseases.
The work was carried out by an international team of academics from the Universities of Cambridge, Oxford and Sheffield in the UK; the Swiss Federal Institute of Technology in Zurich, Switzerland; and the Weizmann Institute of Science in Israel. The study was led by Professor Tuomas Knowles, a Fellow of St John's College at the University of Cambridge and co-director of the Centre for Protein Misfolding Diseases.
"It is a common problem in a range of areas of great practical importance to have active molecules that possess beneficial properties but are challenging to stabilise for storage" Knowles said. "A conceptually simple, but powerful, solution is to put these inside tiny capsules. Such capsules are typically made from synthetic polymers, which can have a number of drawbacks, and we have recently been exploring the use of fully natural materials for this purpose. There is potential to replace plastics with sustainable biological materials, such as silk, for this purpose."
Dr. Ulyana Shimanovich, who performed a major part of the experimental work as a St John's College Post-Doctoral research associate, said: "Silk is a fantastic example of a natural structural material. But we had to overcome the challenge of controlling the silk to the extent that we could mould it to our designs, which are much smaller than the natural silk cocoons."
Dr. Chris Holland, co-worker and head of the Natural Materials Group in Sheffield added: "Silk is amazing because whilst it is stored as a liquid, spinning transforms it into a solid. This is achieved by stretching the silk proteins as they flow down a microscopic tube inside the silkworm."
To imitate this, the researchers created a tiny, artificial spinning duct, which copies the natural spinning process to cause the unspun silk to form into a solid. They then worked out how to control the geometry of this self-assembly in order to create microscopic shells.
Making conventional synthetic capsules can be challenging to achieve in an environmentally friendly manner and from biodegradable and biocompatible materials. Silk is not only easier to produce; it is also biodegradable and requires less energy to manufacture.
"Natural silk is already being used in products like surgical materials, so we know that it is safe for human use," Professor Fritz Vollrath head of the Oxford Silk Group said. "Importantly, the approach does not change the material, just its shape."
Silk micrococoons could also expand the range and shelf-life of proteins and molecules available for pharmaceutical use. Because the technology can preserve antibodies, which would otherwise degrade, in cocoons with walls that can be designed to dissolve over time, it could enable the development of new treatments against cancer, or neurodegenerative conditions such as Alzheimer's and Parkinson's Diseases.
To explore the viability of silk microcapsules in this regard, the researchers successfully tested the micrococoons with an antibody that has been developed to act on alpha-synuclein, the protein that is thought to malfunction at the start of the molecular process leading to Parkinson's Disease. This study was carried out with the support of the Cambridge Centre for Misfolding Diseases, whose research programme is focused on the search for ways of preventing and treating neurodegenerative conditions such as Alzheimer's and Parkinson's diseases.
"Some of the most efficacious and largest selling therapeutics are antibodies," Michele Vendruscolo, co-director of the Cambridge Centre of Misfolding diseases, said. "However, antibodies tend to be prone to aggregation at the high concentrations needed for delivery, which means that they are often written off for use in treatments, or have to be engineered to promote stability."
"By containing such antibodies in micrococoons, as we did here, we could significantly extend not just their longevity, but also the range of antibodies at our disposal," Knowles said. "We are very excited by the possibilities of using the power of microfluidics to generate entirely new types of artificial materials from fully natural proteins."
The study, Silk microcooons for protein stabilisation and molecular encapsulation, is published in Nature Communications.
Tom Kirk | EurekAlert!
Princeton-UPenn research team finds physics treasure hidden in a wallpaper pattern
20.07.2018 | Princeton University
Relax, just break it
20.07.2018 | DOE/Argonne National Laboratory
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
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The if-else statement is one of the widely used control flow statements while programming. It lets the program execute a set of statements enclosed within the "if" block only if the certain condition evaluates to true otherwise program executes statements of "else" block. So it provides the facility to the programmer to handle the condition based programming.
Syntax for if-else:
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The Atmosphere — Ice — Water Interface: On the necessity of boundary layer modelling
In his search for energy sources and minerals, man has started to develop the high potential wealth of the Arctic. Thus, we must promote climatological, ecological, hydrographical and meteorological studies, to provide knowledge of how nature behaves in this region. Such knowledge must then be used to set recommendations or guidelines for the establishment of industrial plants, inhabited centres, etc. Problems connected with the diffusion of pollutants under temperature inversion conditions are of especial interest.
Such developments will in turn activate communications so that, for example, shipping will need precise knowledge of sea-ice situations, ice drift and formation of pressure ridges.
There is need also for forecasting snowstorms, fog formation, riming or icing of structures, etc. all of which can be highly destructive in these latitudes.
Recent efforts for improving the reliability and the length of weather forecasts (for example, the European Centre for Medium Range Weather Forecasts in Reading, United Kingdom) have prompted the organisation of extensive international experiments, for example, GATE and FGGE (GARP, 1970, 1973), aimed at studying the basic energy source of the atmospheric machine, that is, the equatorial and tropical zones. However, polar regions act as the main energy sink, and are modulated by the extent of sea ice. This side of the problem should be studied equally intensively. Without doubt, the pioneering work of the AIDJEX Group (Maykut, Thorndike and Untersteiner, 1972; Untersteiner, 1974) provides a good start, which must now be extended (AIDJEX, 1977, 1978). It should also be noted that polar meteorology can have a direct connection with mid-latitudes weather (Weiler, 1975; see also the special issue of Dynamics of Atmospheres and Oceans (1979), 3,2–4).
KeywordsMixed Layer Arctic Ocean Atmospheric Boundary Layer Planetary Boundary Layer Richardson Number
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Researchers use spectroscopic tools to analyze H2 activation by [FeFe]-Hydrogenase HydA1 from Chlamydomonas reinhardtii.
- [NREL] NREL Shows How Cyanobacteria Build Hydrogen-Producing Enzyme
- [NREL] New Screening System Detects Algae with Increased H2 Production
- [NREL] Advantages of Enzyme Could Lead to Improved Biofuels Production
- [NREL] Novel Combination of Enzyme Systems Could Lower Biofuel Costs
- [NREL] NREL Simulations Provide New Insight on Polymer-Based Energy Storage Materials
Hydrogenases are enzymes found in microbes that catalyze hydrogen production at fast rates (>104 s-1), and they are endowed with unique organometallic catalytic sites composed of earth-abundant metals (e.g., Fe, Ni). Investigations on the natural diversity of hydrogenases and how they operate deliver key principles for guiding the design of more efficient synthetic catalysts derived from nonprecious metals. Research should read: NREL Shows How Cyanobacteria Build Hydrogen-Producing Enzyme.
Researchers from the National Renewable Energy Laboratory (NREL) and their partners from Montana State University uncovered new, detailed information about how these enzymes function, making their mechanistic understanding for the H2 activation process more complete. The potential to activate hydrogen at higher rates and efficiencies to produce H2 is thereby advanced.
The researchers used electron paramagnetic resonance (EPR) and infrared (IR) spectroscopies to identify new electronic and vibrational information for the catalytic site H-cluster of [FeFe]-hydrogenases under turnover.
While a general model of H2 activation exists for [FeFe]-hydrogenases, the structural and bio-physical properties of the intermediates of the catalytic site H-cluster are poorly defined. The simplicity of algal [FeFe]-hydrogenases enables new access to catalytically relevant intermedi- ates that were not detected in previous studies focused on more complex enzymes isolated from bacteria.
Uncovering the mechanistic details of how the unique active site of hydrogenases activate H2 helps to provide the essential requirements for the design of efficient bio-inspired syn- thetic catalysts. The new spectral details are leading to a more complete model of how these extraordinary enzymes can function to activate H2 at unparalleled rates and efficiencies.
Key Research Results
The researchers used electron paramagnetic resonance and infrared spectroscopies to reveal new mechanistic details during catalytic turnover of H2.
Findings indicate that the complete activation/oxidation of H2 is a coupled two-electron/two-proton reaction, and it is possible that electronic transitions to a [4Fe-4S]1+ cluster at the catalytic site are made during each successive turnover event, signifying its role to mediate electron transfer during H2 catalysis.
Developing a fundamental understanding of the mechanisms by which enzymes activate small molecules like H2 and catalyze fuel- forming reactions may lead to more efficient synthetic catalysts for future development of renewable energy solutions.
Technical Contact: Paul King, email@example.com
Reference: Mulder, D.W.; Ratzloff, M.W.; Shepard, E.M.; Byer, A.S.; Noone, S.M.; Peters, J.W.; Broderick, J.B.; King, P.W. (2013). “EPR and FTIR Analysis of the Mechanism of H2 Activation by [FeFe]- Hydrogenase HydA1 from Chlamydomo- nas reinhardtii.” Journal of the American Chemical Society 135; pp. 6921-6929. dx.doi.org/10.1021/ja4000257.
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Scientists advanced their recent development of laser-induced graphene by producing and testing stacked, three-dimensional supercapacitors, energy-storage devices that are important for portable, flexible electronics.
Scientists developed a method to form micropores of less than 2 nanometers within porous polymers where 10 nanometers long mesopores are connected like a net. The best feature of the porous polymers is the fast absorption of molecules.
Engineers have now devised a new kind of graphene-based biosensor that works in three ways at once. Because proteins trigger three different types of signals, the sensor can triangulate this information to produce more sensitive and accurate results.
The Centre for Process Innovation is leading a European collaborative project that aims to transform food waste into a sustainable source of significant economic added value, namely graphene and renewable hydrogen.
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Under appropriate conditions, a cloud of several hundred atoms can behave like a single atom, virtually developing super-power. Upon excitation with an ultraviolet laser into highly excited states, the atoms start to interact with each other.
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Population dynamics, reproduction and growth of the Indo-Pacific horned sea star, Protoreaster nodosus (Echinodermata; Asteroidea)
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The horned sea star (Protoreaster nodosus) is relatively common in the Indo-Pacific region, but there is little information about its biology. This study of the population biology of P. nodosus was carried out in Davao Gulf, The Philippines (7°5′N, 125°45′E) between September 2006 and May 2008. Protoreaster nodosus was found in sand and seagrass dominated habitats at a mean density of 29 specimens per 100 m2 and a mean biomass of 7.4 kg per 100 m2, whereas a significantly lower density and biomass was found in coral and rock dominated habitats. Adult specimens (mean radius R = 10.0 cm) were found at depths of 0–37 m, whereas juveniles (R < 8 cm) were only found in shallow sandy habitats with abundant seagrass (water depth ≤2 m). Increased gonad weights were found from March to May (spawning period), which coincided with an increasing water temperature and a decreasing salinity. Density and biomass did not change significantly during reproduction, but sea stars avoided intertidal habitats. All specimens with R > 8 cm had well developed gonads and their sex ratio was 1:1. Protoreaster nodosus grew relatively slowly in an enclosure as described by the exponential function G = 7.433 e−0.257 × R . Maturing specimens (R = 6–8 cm) were estimated to have an age of 2–3 years. Specimens with a radius of 10 cm (population mean) were calculated to have an age of 5–6 years, while the maximum age (R = 14 cm) was estimated as 17 years. Potential effects of ornamental collection on the sea star populations are discussed.
KeywordsPatch Reef Full Moon Seagrass Meadow Larval Period Intertidal Habitat
We greatly acknowledge E. Santos and K. Schröder for supporting the initiation of the project. We thank I. Ebol, C. Ganadores, E. Glimada, J. Lagarteja, B. Müller, S. Nitza, S. A. Nitza, D. Padrogane, C. Petiluna, M. Saceda, F. Salac, J. Salinas, I. Santamaria and R. Tejada for supporting the fieldwork. Furthermore, we would like to thank R. Scheibling, B. Wilkinson, and two anonymous reviewers for their comments on an earlier version of this manuscript. We for fine-tuning the English language. We are grateful to the communities from Samal Island and Talikud Island for sharing their knowledge of the local marine resources. The performed experiments complied with the current laws of the Republic of the Philippines.
This article is distributed under the terms of the Creative Commons Attribution Noncommercial License which permits any noncommercial use, distribution, and reproduction in any medium, provided the original author(s) and source are credited.
- Bos AR, Alipoyo JCE, Cardona LT, Gumanao GS, Salac FN (2008b) Population structure of common Indo-Pacific sea stars in the Davao Gulf, Philippines. In: Proceedings of 9th biannual meeting philippine association of marine science. UPV J Nat Sci 13 (accepted)Google Scholar
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- Wabnitz C, Taylor M, Green E, Razak T (2003) From ocean to aquarium. UNEP-WCMC, Cambridge, UKGoogle Scholar | <urn:uuid:923897b5-4ea8-44a1-a2ef-a560a8b2db78> | 2.515625 | 1,173 | Academic Writing | Science & Tech. | 50.078202 | 95,644,986 |
Common name: a copepod
available through www.itis.gov
Size: Less than 1 mm
Native Range: The genus has a worldwide distribution. However, Bruno et al. (2000) believe it may be introduced to North America from Eurasia as a large majority of records come from disturbed habitats.
Interactive maps: Point Distribution Maps
Puerto Rico &
Table 1. States with nonindigenous occurrences, the earliest and latest observations in each state, and the tally and names of HUCs with observations†. Names and dates are hyperlinked to their relevant specimen records. The list of references for all nonindigenous occurrences of Elaphoidella bidens bidens are found here.
Table last updated 5/25/2018
† Populations may not be currently present.
* HUCs are not listed for states where the observation(s) cannot be approximated to a HUC (e.g. state centroids or Canadian provinces).
Ecology: This species inhabits freshwater lakes, streams, reservoirs, and marshes; can tolerate eutrophic waters (Hudson and Lesko, 2003).
Means of Introduction: Unknown, but because it has also been found in the Great Lakes, ballast water may have been how it was introduced initially.
Impact of Introduction: Unknown.
References: (click for full references)
Bruno, M.C., J.W. Reid, and S.A. Perry. 2000. New records of copepods from Everglades National Park (Florida): description of two new species of Elaphoidella (Harpacticoida, Canthocamptidae), and supplementary description of Diacyclops nearcticus Kiefer (Cyclopoida, Cyclopidae). Crustaceana 73:1171-1204.
Hudson, P.L., and L.T. Lesko. 2003. Free-living and Parasitic Copepods of the Laurentian Great Lakes: Keys and Details on Individual Species. Ann Arbor, MI: Great Lakes Science Center Home Page. http://www.glsc.usgs.gov/greatlakescopepods/
McLaughlin, P.L. and 38 others. 2005. Common and scientific names of aquatic invertebrates from the United States and Canada: Crustaceans. American Fisheries Society Special Publication 31, Bethesda, Maryland.
Revision Date: 3/1/2013
Benson, A.J., 2018, Elaphoidella bidens bidens (Schmeil, 1894): U.S. Geological Survey, Nonindigenous Aquatic Species Database, Gainesville, FL, https://nas.er.usgs.gov/queries/FactSheet.aspx?SpeciesID=2772, Revision Date: 3/1/2013, Access Date: 7/16/2018
This information is preliminary or provisional and is subject to revision. It is being provided to meet the need for timely best science. The information has not received final approval by the U.S. Geological Survey (USGS) and is provided on the condition that neither the USGS nor the U.S. Government shall be held liable for any damages resulting from the authorized or unauthorized use of the information. | <urn:uuid:eb23d8f1-0c08-4fbe-8219-6a659cbc781e> | 3.21875 | 690 | Knowledge Article | Science & Tech. | 49.233126 | 95,644,997 |
Humans are fascinated by sharks. And the larger the shark is, the tighter its grip on our collective imagination. So et's take a look at the biggest shark of them all: the Carcharocles megalodon.
C. megalodon is thought to have grown to approximately 60 feet long, and to have gone extinct around 2.6 million years ago. However, not everyone is convinced that megalodon is dead and gone. Some megalodon truthers think the massive shark is alive and well and living undiscovered in the Earth's oceans—and they often point to the sightings described below as evidence.
Even if you believe that megalodon is long extinct (in which case, you're in good hands; scientists everywhere agree with you!), the myth of the modern megalodon is still fascinating. If nothing else, these alleged megalodon sightings prove humans are fascinated by the ocean's mysterious depths. And in an ideal world, that fascination might lead to increased interest in conservation of actual extant sharks.
HMS Challenger Teeth
This first entry isn't a sighting, but a fossil find that's sometimes brought up and frequently misinterpreted in discussions of whether or not megalodon is still with us.
In 1875, the British ship HMS Challenger pulled up a pair of megalodon teeth from a seabed. In 1959, Dr. W. Tschernezky of London’s Queen Mary College attempted to date the teeth by studying the buildup of the manganese dioxide layer on each tooth. Through examining manganese dioxide deposition, Tschernezky determined the teeth were 11,000 and 24,000 years old, respectively. If correct, those findings would indicate that at the very least, megs may have gone extinct far later than previously thought.
However, manganese dioxide dating is often unreliable, particularly in dating shark teeth. As Ben S. Roesch writes in the 1998 Cryptozoology Review article "A Critical Evaluation of the Supposed Contemporary Existence of Carcharodon megalodon," shark teeth are more durable than typical fossil bones, and are able to withstand considerable erosion. This can make it challenging to determine how old the teeth actually are. Many researchers now think it likely that shark teeth once believed to be post-Pliocene megalodon teeth were instead older specimens that were somehow moved from their original, older sedimentary layer and deposited in a younger layer.
David Stead and the 'giant' fish
In his book Sharks and Rays of the Australian Seas, Australian naturalist David Stead shared an anecdote, which some believe describes a terrifying encounter with Meg herself.
According to Stead, in 1981 he spoke with several crayfish fishermen who were so terrified of a shark they saw in their fishing grounds off Broughton Island that they refused to return to the ground for days. They claimed to have seen a shark of unbelievable size surface in the deep water of the fishing grounds, taking the pots and mooring with it. Given that the crayfish pots were over three feet in diameter and loaded with heavy catch, that would be no small feat. Stead and the local Fisheries Inspector, a Mr. Paton, questioned the men, who all agreed to the shark's monstrous size—one claimed that its head alone was "at least as long as the roof on the wharf shed at Nelson's Bay." Many said it measured around 115 feet in length. Others said the water seemed to boil where it surfaced. All of them were confident that it was a shark rather than a whale, and that it was pale white in coloring. Given that the men they spoke to were all hardened fishermen accustomed to sharks, whales, and other sea creatures, the conversations they had with these frightened witnesses left quite an impression on Stead and Mr. Paton.
But even if the shark observed by the fishermen were as massive as described, several signs indicate that it couldn't have been mighty meg. As Roesch writes in his 1998 paper, if megalodon were alive in the modern world and surviving in the deep sea, it's unlikely he would be the white color described in the 1918 accounts. Most deep-sea sharks are dark, rather than white, although there is a general misconception that dark, deep-sea habitats result in lack of pigmentation.
An 'immense shark' off the Great Barrier Reef
In his 1978 book Let's Go Fossil Shark Tooth Hunting, author B.C. Cartmell describes an alleged incident that took place off the edge of Australia's Great Barrier Reef in the 1960s.
According to Cartmell, the sailors involved initially refused to speak of the incident because they feared teasing. But after time, they admitted that when their 85-foot ship was forced to weigh anchor for engine repairs, the captain and crew were shocked to see a gargantuan white shark swim slowly past their stuck ship. It rivaled the boat in size. All aboard agreed it was not a whale.
Was it the megster? Probably not—but whatever the sailors saw that day, it's proof that the ocean is a fascinating place.
The 'Black Demon' of Cortez
The Black Demon of Cortez is believed to be a massive, black shark seen off Mexico's Baja Coast. Some reports allege that the big boy may even be comparable in size to the ancient megalodon. In one alleged encounter, fisherman Eric Mack reported that the Black Demon rocked his boat, while its towering tail stuck five feet out of the water. Of course, if the 'Black Demon' is real, that doesn't mean it's a megalodon—it could easily be a plankton-eating whale shark or even a large great white with melanism.
The enormous black shark was the focus of an episode of the History channel cryptozoology TV show Monsterquest. However, the investigators failed to find any evidence of the fabled 'demon.'
Zane Grey and the 'man-eating monsters of the South Pacific'
Novelist and deep-sea angler Zane Grey claimed to have had an experience with a massive shark that some believe could have been a megalodon. In the novel Megalodon: Fact or Fiction?, Rick Emmer writes that Grey claimed to have seen "one of the man-eating monsters of the South Pacific," a shark much longer than his 30-40-foot boat. Apparently, the shark was "yellow and green ... (with a) square head, immense pectoral fins and a few white spots." In other words, not a mere "harmless white shark."
What does it all mean?
As fun as it is to imagine these stories are evidence that megalodon is still alive, that's just not the case. As Meghan Balk, a megalodon researcher at the University of New Mexico, told The Daily Beast: “there is no doubt in the scientific community that Megalodon is extinct.”
Balk explains that megalodons stayed close to the coast, so if they were still alive today, we'd know—it would be hard to miss a 50-plus-foot super predator roaming the shores! According to Balk, "most large sharks occur in the upper 500 meters of the water column, probably due to productivity. The deep is much too nutrient poor to support such a large animal."
In many ways, Shark Week is responsible for popularizing the myth that megalodon is still around. In 2014, Discovery aired the highly controversial Shark Week 'mockumentary' ''Megalodon: The Monster Shark Lives.'' The incredibly misleading program presented 'evidence' that megalodon was not only still alive, but also attacking humans and boats. Although a brief disclaimer at the end of "The Monster Shark Lives" explained that it was a work of fiction, many viewers were understandably fooled by the 'eyewitness accounts' and interviews with 'scientists.' The next year, Discovery aired a follow-up mockumentary called "Megalodon: The New Evidence," which only compounded the confusion.
Sadly, even if megalodon were discovered to be alive today, experts say it's likely humans would soon put them on the path to extinction again.
Conservationist, shark expert, and Shark Week critic David Shiffman wrote in 2014 that if megalodon were alive today, it would probably be hunted to extinction for its fins. He estimates that if hypothetical modern-day megalodon has 1.5 metric tons of fins, it could be sold for around $600,000, and make approximately 70,456 bowls of megalodon shark fin soup.
And, as Shiffman points out, "if the hypothetical overfishing of a species that has been extinct for millions of years has you as upset as it has me, you should learn more about the real overfishing of shark species that are still around… at least for now." | <urn:uuid:df10bc31-c24f-4976-ad4e-54d6e15b0088> | 4 | 1,836 | Personal Blog | Science & Tech. | 51.787124 | 95,644,999 |
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Army Corps of Engineers: Lake Okeechobee flows to slow
Water from Lake Okeechobee and rainfall within the Caloosahatchee watershed are causing water quality issues in the river's estuary. Wochit
The Caloosahatchee River and its estuary will get a little relief soon as the Army Corps of Engineers plans to slow releases starting Friday.
Flows since Hurricane Irma have at times been at maximum flow, with billions of gallons being released from Lake Okeechobee daily.
"Today marks the end of hurricane season," said Lt. Col. Jennifer Reynolds, with the Corps office in Jacksonville. "The lake remains high, although it continues to recede. We are reducing flows to the coasts based on guidance in the Lake Okeechobee Regulation Schedule. This reflects a balance between conserving water in the lake for this dry season while reducing the lake level prior to next storm season."
Flows west to the Caloosahatchee will be reduced to about 2.6 billion gallons a day.
The Corps cited Lake O's steady drop in elevation, the end of the rainy season in late October and the end of the hurricane season Thursday as reasons for the action.
Lake Okeechobee discharges to the St. Lucie River will be cut back Friday, the Army Corps of Engineers announced Thursday afternoon.
The target flow into the river through the St. Lucie Lock and Dam will be slightly less than 1.2 billion gallons a day, according to a news release.
TCPalm.com contributed to this report. | <urn:uuid:9f749740-7da8-42b5-bfe5-8487a2cc3d33> | 2.5625 | 349 | Truncated | Science & Tech. | 50.284122 | 95,645,012 |
The world’s oldest water, which is locked deep within the Earth’s crust, just got even older.
The liquid was discovered deep down in a mine in Canada in 2013 and is about 1.5 billion years old.
But now, at the same site, scientists from the University of Toronto have found a deeper source of water that is at least 500,000 years more ancient.
The research was presented at the American Geophysical Union Fall Meeting in San Francisco.
Professor Barbara Sherwood Lollar, who led the team that made the discovery, told BBC News: “When people think about this water they assume it must be some tiny amount of water trapped within the rock.
“But in fact it’s very much bubbling right up out at you. These things are flowing at rates of litres per minute – the volume of the water is much larger than anyone anticipated.”
The first pool of ancient water was discovered 2.4km-down in a copper, zinc and silver mine.
“It really pushed back our understanding of how old flowing water could be and so it really drove us to explore further,” said Prof Sherwood Lollar.
“And we took advantage of the fact that the mine is continuing to explore deeper and deeper into the earth.”
This new investigation led by Dr Oliver Warr, from the University of Toronto, found water at a depth of nearly 3km.
And tests have revealed that it is at least two billion years old.
It provides scientists with a unique insight into the history of our planet, and gives a glimpse at the life that was present at this time.
The researchers have found chemical traces left behind by tiny single celled organisms that once lived in the fluid.
“By looking at the sulphate in the water, we were able to see a fingerprint that’s indicative of the presence of life,” said Prof Sherwood Lollar.
“And we were able to indicate that the signal we are seeing in the fluids has to have been produced by microbiology – and most importantly has to have been produced over a very long time scale.
“The microbes that produced this signature couldn’t have done it overnight. This isn’t just a signature of very modern microbiology.
“This has to be an indication that organisms have been present in these fluids on a geological timescale.”
The researchers say that studying watery sites like this on Earth could give them clues about where life might reside elsewhere in the Solar System, such as the oceans on the icy moons of Saturn and Jupiter.
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As you saw in the previous chapter, the list data type is an illusion created by a set of functions that manipulate cons cells. Common Lisp also provides functions that let you treat data structures built out of cons cells as trees, sets, and lookup tables. In this chapter I’ll give you a quick tour of some of these other data structures and the functions for manipulating them. As with the list-manipulation functions, many of these functions will be useful when you start writing more complicated macros and need to manipulate Lisp code as data.
KeywordsHash Table Lookup Table Original List List Structure Treat Data Structure
Unable to display preview. Download preview PDF. | <urn:uuid:b3f1fe2e-63c6-4227-babf-e1a84d540b6f> | 3.15625 | 136 | Truncated | Software Dev. | 48.342572 | 95,645,031 |
Add command descriptions
|Deletions are marked like this.||Additions are marked like this.|
|Line 56:||Line 56:|
|* set exec-direction [forward | reverse]|
|Line 57:||Line 58:|
|A modal command: when exec-direction is set to "reverse", all ordinary execution commands
such as "step" and "continue" will cause the program being debugged to run in reverse.
== Testing ==
At the time of this writing, the gdb tests for reverse debugging are only supported
for the Process Record target (see [[ProcessRecord#Testing]]).
Reverse Debugging with GDB
Beginning with the 7.0 release in September 2009, gdb now includes support for a whole new way of debugging called "reverse debugging" -- meaning that gdb can allow you to "step" or "continue" your program backward in "time", reverting it to an earlier execution state.
Reverse debugging is only supported for a limited (but growing) number of gdb targets, including:
- Certain remote targets including the Simics and SID simulators, and "Undo-db"
The Process Record and Replay target for native linux.
Anyone who has used a debugger has probably had the experience of suddenly realizing that you have accidentally gone too far -- the event you were looking for has passed, and you missed seeing it. With reverse debugging, instead of starting the program over from the beginning and repeating your entire (possibly lengthy) debugging session, you can simply set a breakpoint at an earlier point in the program, and "reverse-continue", causing the program to back up and "undo itself" to that earlier point, from which you can proceed forward again. Or, you can "reverse-step" and "reverse-next" to back up one program statement at a time (just like normal "step" and "next" take you forward by one program statement).
Reverse Debugging Commands
Assuming you are using one of the gdb targets that supports reverse debugging (such as Process Record for Linux), you can use the following commands:
Run the program backward until it hits a stop event (such as a breakpoint, watchpoint, or exception).
Run the program backward until the beginning of the previously-executed source line.
Run the program backward for exactly one machine instruction.
Like "next" in reverse -- function calls are stepped over instead of into (in reverse).
Like "nexti" in reverse -- executes one machine instruction (backward), unles that instruction is a return from a function call, in which case the entire function will be executed in reverse.
By analogy to the "finish" command, "reverse-finish" executes the current function in reverse, until the execution reaches the calling function, then stops.
- set exec-direction [forward | reverse]
A modal command: when exec-direction is set to "reverse", all ordinary execution commands such as "step" and "continue" will cause the program being debugged to run in reverse.
At the time of this writing, the gdb tests for reverse debugging are only supported for the Process Record target (see ProcessRecord#Testing). | <urn:uuid:e476b7f6-d699-4a07-8dce-6c428ad2af4f> | 2.84375 | 678 | Documentation | Software Dev. | 33.113436 | 95,645,071 |
Marty Holmes, a landscaper from Stockton, Calif., had never heard of a regulatory T cell before his doctor suggested that it could be the key to helping him survive his cancer.
Holmes recalled that he didnt bat an eye when the doctors proposed an experimental radiation and drug procedure to help boost these cells, even though it had been tested almost solely in mice. "As long as there was any percentage of hope, I just shot for that," he said of the decision he made last year. "I felt privileged to be a human guinea pig."
Findings published in the Sept. 29 issue of the New England Journal of Medicine suggest that the new therapy pioneered at Stanford University School of Medicine has paid off for Holmes and other lymphoma and leukemia patients. Holmes became the 40th person to undergo this procedure after Stanford researchers had shown that it could boost the relative levels of regulatory T cells in the immune system of mice - an effect that turned out to be beneficial before undergoing a hematopoietic (blood) stem cell transplantation, a common treatment for blood cancers.
Mitzi Baker | EurekAlert!
Scientists uncover the role of a protein in production & survival of myelin-forming cells
19.07.2018 | Advanced Science Research Center, GC/CUNY
NYSCF researchers develop novel bioengineering technique for personalized bone grafts
18.07.2018 | New York Stem Cell 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....
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Thalassoma amblycephalum (Bleeker, 1856)
Abundant in the Solitary Islands Marine Park. Distributed throughout the Indo-Pacific region: from Somalia and South Africa, to the Line, Marquesan and Tuamoto Islands, north to southern Japan, south to northern New Zealand, Rapa and Lord Howe Islands. In Australia recorded from around Geraldton in Western Australia north to the Timor Sea, from the northern Great Barrier Reef south to southern New South Wales and including Lord Howe Island.
Frequents shallow lagoon and seaward reefs, reef flats. Depth 1 - 15 m.
Brightly coloured male, slender body and with lunate tail. Juveniles commonly in small schools close to coral or substrate, with green back, pale belly and often orange on top and bottom of tail base. Difficult to approach and constantly move across the substrate where they feed on small crustaceans and other invertebrates. Adults uncommon and solitary. Juveniles pictured in middle photograph, tiny juvenile 25 mm long in bottom photograph. Grows to 16 cm.
R. Stuart-Smith, G. Edgar, A. Green, I. Shaw, Tropical Marine Fishes of Australia. Reed New Holland Publishers, 2015. p.336.
Atlas of Living Australia website at https://bie.ala.org.au/search?q=Thalassoma+amblycephalum. Accessed 10/07/18.
FishBase. Froese, R. and D. Pauly. Editors. 2018. World Wide Web electronic publication. https://fishbase.ca/summary/thalassoma-amblycephalum.html. Accessed 10/07/18. | <urn:uuid:75311d7c-4f38-49f8-9126-afcb1b172581> | 3.015625 | 350 | Knowledge Article | Science & Tech. | 57.903693 | 95,645,112 |
Process uses light-harvesting nanoparticles, captures energy from 'hot electrons'
Rice University researchers have demonstrated an efficient new way to capture the energy from sunlight and convert it into clean, renewable energy by splitting water molecules.
The technology, which is described online in the American Chemical Society journal Nano Letters, relies on a configuration of light-activated gold nanoparticles that harvest sunlight and transfer solar energy to highly excited electrons, which scientists sometimes refer to as "hot electrons."
"Hot electrons have the potential to drive very useful chemical reactions, but they decay very rapidly, and people have struggled to harness their energy," said lead researcher Isabell Thomann, assistant professor of electrical and computer engineering and of chemistry and materials science and nanoengineering at Rice. "For example, most of the energy losses in today's best photovoltaic solar panels are the result of hot electrons that cool within a few trillionths of a second and release their energy as wasted heat."
Capturing these high-energy electrons before they cool could allow solar-energy providers to significantly increase their solar-to-electric power-conversion efficiencies and meet a national goal of reducing the cost of solar electricity.
In the light-activated nanoparticles studied by Thomann and colleagues at Rice's Laboratory for Nanophotonics (LANP), light is captured and converted into plasmons, waves of electrons that flow like a fluid across the metal surface of the nanoparticles.
Plasmons are high-energy states that are short-lived, but researchers at Rice and elsewhere have found ways to capture plasmonic energy and convert it into useful heat or light. Plasmonic nanoparticles also offer one of the most promising means of harnessing the power of hot electrons, and LANP researchers have made progress toward that goal in several recent studies.
Thomann and her team, graduate students Hossein Robatjazi, Shah Mohammad Bahauddin and Chloe Doiron, created a system that uses the energy from hot electrons to split molecules of water into oxygen and hydrogen. That's important because oxygen and hydrogen are the feedstocks for fuel cells, electrochemical devices that produce electricity cleanly and efficiently.
To use the hot electrons, Thomann's team first had to find a way to separate them from their corresponding "electron holes," the low-energy states that the hot electrons vacated when they received their plasmonic jolt of energy. One reason hot electrons are so short-lived is that they have a strong tendency to release their newfound energy and revert to their low-energy state.
The only way to avoid this is to engineer a system where the hot electrons and electron holes are rapidly separated from one another. The standard way for electrical engineers to do this is to drive the hot electrons over an energy barrier that acts like a one-way valve. Thomann said this approach has inherent inefficiencies, but it is attractive to engineers because it uses well-understood technology called Schottky barriers, a tried-and-true component of electrical engineering.
"Because of the inherent inefficiencies, we wanted to find a new approach to the problem," Thomann said. "We took an unconventional approach: Rather than driving off the hot electrons, we designed a system to carry away the electron holes. In effect, our setup acts like a sieve or a membrane. The holes can pass through, but the hot electrons cannot, so they are left available on the surface of the plasmonic nanoparticles."
The setup features three layers of materials. The bottom layer is a thin sheet of shiny aluminum. This layer is covered with a thin coating of transparent nickel-oxide, and scattered atop this is a collection of plasmonic gold nanoparticles -- puck-shaped disks about 10 to 30 nanometers in diameter.
When sunlight hits the discs, either directly or as a reflection from the aluminum, the discs convert the light energy into hot electrons. The aluminum attracts the resulting electron holes and the nickel oxide allows these to pass while also acting as an impervious barrier to the hot electrons, which stay on gold. By laying the sheet of material flat and covering it with water, the researchers allowed the gold nanoparticles to act as catalysts for water splitting. In the current round of experiments, the researchers measured the photocurrent available for water splitting rather than directly measuring the evolved hydrogen and oxygen gases produced by splitting, but Thomann said the results warrant further study.
"Utilizing hot electron solar water-splitting technologies we measured photocurrent efficiencies that were on par with considerably more complicated structures that also use more expensive components," Thomann said. "We are confident that we can optimize our system to significantly improve upon the results we have already seen."
Robatjazi is a graduate student in electrical and computer engineering, Bahauddin is a graduate student in physics and astronomy and Doiron is a graduate student in applied physics. The research was supported by the Welch Foundation and a National Science Foundation CAREER Award.
High-resolution IMAGES are available for download at:
CAPTION: Rice University researchers (clockwise from left) Chloe Doiron, Hossein Robatjazi, Shah Mohammad Bahauddin and Isabell Thomann.
CREDIT: Jeff Fitlow/Rice University
CAPTION: Rice University researchers have demonstrated an efficient new way to capture the energy from sunlight and convert it into clean, renewable energy by splitting water molecules.
CREDIT: I. Thomann/Rice University
CAPTION: Isabell Thomann
CREDIT: Jeff Fitlow/Rice University
A copy of the Nano Letters paper, "Direct Plasmon-Driven Photoelectrocatalysis," is available at: http://pubs.
Located on a 300-acre forested campus in Houston, Rice University is consistently ranked among the nation's top 20 universities by U.S. News & World Report. Rice has highly respected schools of Architecture, Business, Continuing Studies, Engineering, Humanities, Music, Natural Sciences and Social Sciences and is home to the Baker Institute for Public Policy. With 3,888 undergraduates and 2,610 graduate students, Rice's undergraduate student-to-faculty ratio is 6-to-1. Its residential college system builds close-knit communities and lifelong friendships, just one reason why Rice is ranked No. 1 for best quality of life and for lots of race/class interaction by the Princeton Review. Rice is also rated as a best value among private universities by Kiplinger's Personal Finance. To read "What they're saying about Rice," go here.
Jade Boyd | EurekAlert!
Research finds new molecular structures in boron-based nanoclusters
13.07.2018 | Brown University
3D-Printing: Support structures to prevent vibrations in post-processing of thin-walled parts
12.07.2018 | Fraunhofer-Institut für Produktionstechnologie IPT
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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Despite the high temperatures, geologists and climate researchers find evidence that there was sea ice at the North Pole during the last interglacial
Temperatures in the Arctic are currently climbing two to three times faster than the global average. The result - and, thanks to feedback effects, also the cause - is dwindling sea ice. In a study published in the actual volume of Nature Communications, geo- and climate researchers at the Alfred-Wegener Institute, Helmholtz Centre for Polar- and Marine Research (AWI) show that, in the course of our planet's history, summertime sea ice was to be found in the central Arctic in periods characterised by higher global temperatures - but less CO2 - than today.
Prognoses for the future of the Arctic can only be as reliable as the models and data they're based on. The scenarios projected by climate modellers vary greatly, and it remains unclear when we can expect to see the Arctic Ocean free of ice in the summer.
At the same time, there is considerable public interest in dependable predictions concerning Arctic sea ice development over the next few decades, so as to have a basis for long-term strategic planning.
Researchers at the Alfred Wegener Institute have now more closely analysed the glacial history of the central Arctic with the help of sediment core data and climate simulations. Their findings indicate that the region was home to sea ice during the last interglacial, between 115,000 and 130,000 years ago.
"Thanks to the sediment core data, we have clear evidence that, during the last interglacial roughly 125,000 years ago, the central Arctic Ocean was still covered with sea ice during the summer. In contrast, in an area to the northeast of Spitsbergen, the summertime sea ice virtually disappeared," explains Prof Rüdiger Stein, a geologist at the Alfred Wegener Institute and first author of the Nature Communications study, adding, "This is also confirmed by the climate simulations run by AWI modellers involved in the study."
However, comparing the results of the climate simulations for the most recent interglacial with scenario calculations for the future reveals substantial differences: thanks to the more intense solar radiation, back then the air temperatures at higher latitudes were also a few degrees higher than at present. However, the carbon dioxide concentration in the atmosphere - roughly 290 ppm (parts per million) - was ca. 110 ppm lower than the current level, as ice core data from the Antarctic shows.
For their scenario calculations, the AWI modellers plugged in atmospheric CO2 concentrations in excess of 500 ppm, a level in keeping with the forecasts released by the Intergovernmental Panel on Climate Change (IPCC). Under these conditions, a disproportionately rapid retreat of summertime sea ice in the central Arctic Ocean over the course of the next few decades, followed by its complete disappearance - depending on how quickly CO2 levels rise - roughly 250 years from now, is to be expected.
The outcomes of the study reveal the complexity of the processes shaping climate change in the Arctic and point to significant spatial and chronological variances in sea ice cover. To slow the warming of the Arctic and the permanent loss of sea ice, reducing the level of anthropogenic CO2 emissions in the atmosphere is vital.
For the purposes of their study, the researchers used what is referred to as "proxies" - indicators that contain information on past environmental conditions. They concentrated on organic proxies, also known as biomarkers. Some of these biomarkers are produced by certain species of algae, among which one group can only be found in open surface water, while the members of another group only live in sea ice (or did so in the Earth's distant past).
"When we confirm the presence of these algal biomarkers in our sediment layers, it allows us to draw conclusions on the depositional environment and the environmental conditions at the respective time," says Stein. Since the biomarker groups they investigated are based on algae - i.e., on plants that require light for photosynthesis - the absence of both groups is an important indicator of a very thick and largely contiguous ice cover. Such conditions would make photosynthesis impossible, both for the algae in the surface water directly under the ice and those dwelling deeper in the ice close to the ice-water interface.
In addition to these valuable new insights into sea ice distribution during the last interglacial, the study also produced another exciting finding, one concerning the extent of circum-Arctic ice sheets during the Saale glaciation. As Stein relates, "Towards the end of the Saale glaciation (roughly 140,000 to 150,000 years ago), the glaciers most likely extended beyond the outer shelf. They produced masses of cold air that blew out to sea as powerful fall winds (katabatic winds) and created large expanses of open water (polynyas) - a process still frequently observed around the Antarctic continent."
These conditions would seem to contradict the hypotheses put forward by international researchers (Jakobsson et al., 2016), who postulated in 2016 that the glaciers in North America and Eurasia expanded beyond the continental shelf during the Saale glaciation and into open water, covering the entire Arctic Ocean with a nearly kilometre-thick layer of solid ice. "Yet our biomarker data show acceptable living conditions for phytoplankton and sea ice algae, namely open waters and seasonal ice cover - a wide difference to kilometre-thick ice," says Rüdiger Stein.
However, the geologist goes on to explain, "That being said, a chronological sequence of extremely extended thick ice sheets (similar to what Jakobsson et al. have postulated) followed by sea ice formation with polynyas seems to be possible, as the initial results of our own investigations on the southern Lomonosov Ridge have shown. To finally approve this, however, further detailed investigations, especially of well dated sediment cores, are needed."
Ruediger Stein, Kirsten Fahl, Paul Gierz, Frank Niessen & Gerrit Lohmann: Arctic Ocean sea ice cover during the penultimate glacial and the last interglacial. Nature Communications. doi: 10.1038/s41467-017-00552-1.
Your scientific contact partner at the Alfred Wegener Institute is: Rüdiger Stein (Tel: +49 (0)471 4831 - 1576; E-Mail: email@example.com)
At the AWI's Communications and Media Relations department, Folke Mehrtens (Tel: +49 (0)471 4831 - 2007; E-Mail: firstname.lastname@example.org) will be pleased to help you with any questions.
The Alfred Wegener Institute pursues research in the Arctic, Antarctic and the oceans of the middle and high latitudes. It coordinates polar research in Germany, while also providing essential infrastructure for the international scientific community, including the research icebreaker Polarstern and stations in the Arctic and Antarctic. The Alfred Wegener Institute is one of the 18 Research Centres of the Helmholtz Association, the largest scientific organisation in Germany.
Ruediger Stein | 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
16.07.2018 | Physics and Astronomy
16.07.2018 | Life Sciences
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Scientists create new nanostructure with peptides
Published : Apr 19, 2018 - 22:00
Updated : Apr 19, 2018 - 22:00
A group of South Korean scientists has used amino acids and peptides to create a new type of
nanostructure that can be utilized in various industries, a joint university-company team said Thursday.
Many chemicals significant to life have mirror-image twins, a characteristic known as chirality, though it is only observed in organic molecules.
The teams from Seoul National University (SNU), Pohang University of Science and Technology and LG Display Co. have successfully created three-dimensional metallic nanostructures with chirality, SNU said.
The chiral gold nanoparticles interact differently with the circularly polarized visible light to display extensive color modulation, it said. As a result, color change is possible by controlling the light polarization. This has the potential to be used in future display designs.
“Based on the understanding of interface between peptides and inorganic materials, we have built a new platform technology to control the crystallographic asymmetry,” Kim Tae-nam, a lead researcher from SNU. “This finding can make a direct and immediate impact on optical devices.”
The researchers said potential applications include active color display, holography and chirality sensors.
Their research was funded by the Ministry of Science and ICT, and was published in the latest edition of Nature. (Yonhap)
Jul 18, 2018
Jul 18, 2018 | <urn:uuid:ed1e16df-21d8-4de3-ad35-ef4657774cb4> | 2.890625 | 319 | News Article | Science & Tech. | 25.391098 | 95,645,147 |
- Open Access
Short-term spatial change in a volcanic tremor source during the 2011 Kirishima eruption
© The Society of Geomagnetism and Earth, Planetary and Space Sciences (SGEPSS); The Seismological Society of Japan; The Volcanological Society of Japan; The Geodetic Society of Japan; The Japanese Society for Planetary Sciences; TERRAPUB. 2012
Received: 1 December 2011
Accepted: 4 September 2012
Published: 7 May 2013
Volcanic tremors are indicators of magmatic behavior, which is strongly related to volcanic eruptions and activity. Detection of spatial and temporal variations in the source location is important for understanding the mechanism of volcanic eruptions. However, short-term temporal variations within a tremor event have not always been detected by seismic array observations around volcanoes. Here, we show that volcanic tremor sources were activated at both the top (i.e., the crater) and the lower end of the conduit, by analyzing seismograms from a dense seismic array 3 km from the Shinmoedake crater, Kirishima volcano, Japan. We observed changes in the seismic ray direction during a volcanic tremor sequence, and inferred two major sources of the tremor from the slowness vectors of the approaching waves. One was located in a shallow region beneath the Shinmoedake crater. The other was found in a direction N30°W from the array, pointing to a location above a pressure source. The fine spatial and temporal characteristics of volcanic tremors suggest an interaction between deep and shallow conduits.
Volcanic tremors are commonly observed around active volcanoes, and occur in the conduit system between the magma chamber and crater. The duration of most volcanic tremors is much longer than an ordinary tectonic earthquake, and the signal frequency comprises fundamental, and harmonic, oscillations (McNutt, 2005). Based on seismic observations, numerous studies have modeled the mechanical source of volcanic tremors (e.g., Julian, 1994; Chouet et al., 1997; Hellweg, 2000; Jellinek and Bercovici, 2011). Seismic array observations that use slowness analysis of seismic waves are a powerful tool for locating the origin of tremors. In particular, array analyses using the multiple signal classification (MUSIC) technique (Schmidt, 1986; Kikuma, 1999) have revealed the properties of mag-matic activity in volcanic regions (Goldstein and Chouet, 1994).
2. Slowness Analysis of Volcanic Tremors
After the start of the eruption, a seismic array was urgently deployed on 29 January, 2011, along a road 3 km from the Shinmoedake crater in the direction N115°W. Twenty-five 3-component seismometers with a natural frequency of 2 Hz were installed at a sensor interval of 20–40 m. The location and shape of the array, and array response functions at 2 Hz, are shown in Fig. 1. Data was sampled every 1 ms by a recording system controlled by a GPS-calibrated clock. In this study, we use seismograms recorded by 23 of the 25 sensors with good signal-to-noise (S/N) ratios. We also installed a broadband seismometer at the center of the seismic array (KU.KRSY in Fig. 1).
3. Estimated P-, and Surface, Wave Slowness
4. Origin of the Volcanic Tremor
Next, we investigate the variation in slowness within the part of the seismic ray originating from the direction of the crater. Figure 2(b) displays the cross-section in the slowness-time domain for a fixed azimuth of 65°. Generally, the slowness varies from 0.15 to 1.0 s/km. We divide the seismogram into five types, according to the detailed slowness and ray directions of the tremor. These are wavelets from the crater with slowness values (s) of approximately (W) s < 0.42 (P-wave slowness); (X) 0.42 ≤ s < 1.0; (Y) s = 1.0 s/km (surface wave slowness); and (Z) from the direction N30°W. The waves (X) are S-waves because the slowness exceeds that for P-waves. The slowness variation corresponds to the change in the source depth and/or the wave type. The waves categorized as (W) and (X) probably travelled from the source at depths at-, and below, the location of the explosion source. The source for the waves (Y) is probably located close to the surface of the crater because the waves propagated at surface wave speeds. As seen in Fig. 2(b), the sequence of the tremor occurrence has an interesting feature, in that wave type (Y) seems to follow the occurrence of the tremor with types (W) and (X).
5. Discussion and Summary
Volcanic tremors are phenomena commonly observed worldwide. Magma behavior is of great importance for monitoring and predicting volcanic activity. Our results have revealed part of this behavior, implying that dense seismic array observations with a high sampling rate can contribute to our understanding of volcanic activity and contribute to the prediction of eruptions. However, a multi-array analysis, which we were unable to conduct in this study, is required to determine the exact location of the tremor source and the conduit geometry. In addition, geodetic observation is also needed to monitor magma behavior. Such comprehensive observations will enable further understanding of the behavior of volcanic eruptions.
We wish to thank Edoardo Del Pezzo and the anonymous reviewer for their comments, which helped to improve the manuscript. We are grateful for the assistance of Kyushu University during the temporary observations. This study was partially supported by JSPS KAKENHI Grant Number 24540457.
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If you're searching for Copper (Cu): Fun Facts and Information About the Element to help with your children's homework, to use as a website resource for your classroom, or to use in your lesson plan for your students, the information below can help.
What is the symbol? Cu
What is the atomic number? 29
What is the atomic weight? 63.546
What is the melting point in Celsius? 1083
What is the boiling point in Celsius? 2567
What is the density (g/cm3)? 8.96
What year was it discovered? ancient
Who discovered the element? Known since ancient times
What group is the element in? 11
What is the electron configuration? [Ar] 3d10 4s1
What is the ionization energy? 7.7264
What element category is it in? Transition Elements
Where is Copper Found?
Large copper ore deposits are found in the U.S., Chile, Zambia, Zaire, Peru, and Canada. The most important copper ores are the sulfides, the oxides, and carbonates. From these, copper is obtained by smelting, leaching, and by electrolysis.
What is Copper Used For?
The electrical industry is one of the greatest users of copper. Iron’s alloys — brass and bronze — are very important: all American coins are copper alloys and gun metals also contain copper.
Copper has wide use as an agricultural poison and as an algaecide in water purification. Copper compounds, such as Fehling’s solution, are widely used in analytical chemistry tests for sugar.
Below you will find additional resources and facts for kids related to the article "Copper (Cu): Fun Facts and Information About the Element". | <urn:uuid:8e55472a-4126-48db-b7a8-ee0780d3a06a> | 3.4375 | 370 | Knowledge Article | Science & Tech. | 59.953278 | 95,645,177 |
NOTE: Most of the High Level Science Products are unavailable while unscheduled maintenance is being performed. They will be incrementally restored over the course of this week. We apologize for any inconvenience.
The International Ultraviolet Explorer (IUE) satellite was a unique space observatory in that it was operated like a ground-based observatory. Astronomers came to the Telescope Operations Center and directed their observations while observatory staff members commanded the instrument and read down the data in real time. It was launched on January 26, 1978, and operated for nearly 19 years until September 30, 1996. The instrumentation included two spectrographs, one from 2000 to 3300 Å and the other from 1200 to 2000 Å, in both high (R ~ 10,000) and low (R ~ 300) resolution modes.
The archive of over 107,000 spectral images includes about 9200 individual objects, many of which were observed repeatedly for variability studies. All types of astronomical objects, from planets to galaxies, were observed by IUE but a major portion of the archive is devoted to stellar observations. The search form may be used to select data from the IUE catalog by object name, coordinates, observing mode, date of observation, etc. The data files of interest may then be marked and retrieved.
MAST holdings contain the fully reduced and calibrated spectra in
two versions. The first version consists of the original
processed data using the
IUE Spectral Image Processing Software (IUESIPS).
The data files
are stored in VICAR header format and can be
read and analyzed with the IUE Data Analysis Center (IUEDAC)
written in IDL.
The data were later reprocessed using new calibrations and
improved processing techniques
producing a second version
known as the IUE Final Archive. The NEWSIPS
data files are
stored in FITS format and may be read with a variety of FITS
readers, including iuetools
in IRAF and programs in
the IUEDAC software package.
The Final Archive data are the
preferred version for most applications, but both versions are | <urn:uuid:13a11441-486a-4124-bb78-3ba9c238538a> | 2.921875 | 445 | Knowledge Article | Science & Tech. | 32.964063 | 95,645,201 |
ASP.NET Web Pages - Folders
This chapter is about folders and folder paths.
In this chapter you will learn:
- About Logical and Physical folder structures
- About Virtual and Physical names
- About web URLs and Paths
Logical Folder Structure
Below is a typical folder structure for an ASP.NET web pages web:
- The "Account" folder contains logon and security files
- The "App_Data" folder contains databases and data files
- The "Images" folder contains images
- The "Scripts" folder contains browser scripts
- The "Shared" folder contains common files (like layout and style files)
Physical Folder Structure
The physical structure for the "Images" folder at the website above might look like this on a computer:
Virtual and Physical Names
From the example above:
The virtual name of a web picture might be "Images/pic31.jpg".
But the physical name is "C:\Johnny\Documents\MyWebSites\Demo\Images\pic31.jpg"
URLs and Paths
URLs are used to access files from the web: http://www.welookups.com/html/html5_intro.asp
The URL corresponds
to a physical file on a server: C:\MyWebSites\welookups\html\html5_intro.asp
A virtual path is shorthand to represent physical paths. If you use virtual paths, you can move your pages to a different domain (or server) without having to update the paths.
The root on a disk drive is written like C:\, but the root on a web site is / (forward slash).
The virtual path of a web folder is (almost) never the same as the physical folder.
In your code you will, reference both the physical path and the virtual path, depending on what you are coding.
ASP.NET has 3 tools for working with folder paths: the ~ operator, the Server.MapPath method, and the Href method.
The ~ Operator
To specify the virtual root in programming code, use the ~ operator.
If you use the ~ operator, instead of a path, you can move your website to a different folder or location without changing any code:
var myStyleSheet = "~/styles/StyleSheet.css";
The Server.MapPath Method
The Server.MapPath method converts a virtual path (/default.cshtml) to a physical path that the server can understand (C:\Johnny\MyWebSited\Demo\default.cshtml).
You will use this method when you need to open data files located on the server (data files can only be accessed with a full physical path):
var fileName = Server.MapPath(pathName);
You will learn more about reading from (and writing to) data files on the server in the next chapter of this tutorial.
The Href Method
The Href method converts a path used in the code to a path that the browser can understand (the browser cannot understand the ~ operator).
You use the Href method to create paths to resources like image files, and CSS files.
You will often use this method in HTML <a>, <img>, and <link> elements:
<!-- This creates a link to the CSS file. -->
<link rel="stylesheet" type="text/css" href="@Href(myStyleSheet)" />
<!-- Same as : -->
<link rel="stylesheet" type="text/css" href="/Shared/Site.css" />
The Href method is a method of the WebPage Object. | <urn:uuid:b18d01a2-81ad-4800-a31a-df9abf00c869> | 2.9375 | 777 | Tutorial | Software Dev. | 57.069364 | 95,645,207 |
A nuclear explosion is an explosion that occurs as a result of the rapid release of energy from a high-speed nuclear reaction. The driving reaction may be [nuclear fission] or [nuclear fusion] or a multistage cascading combination of the two, though to date all fusion-based weapons have used a fission device to initiate fusion, and a pure fusion weapon remains a hypothetical device.
Atmospheric nuclear explosions are associated with mushroom clouds, although mushroom clouds can occur with large chemical explosions. It is possible to have an air-burst nuclear explosion without those clouds. Nuclear explosions produce radiation and radioactive debris.
This section needs expansion. You can help by adding to it. (November 2008)
The first man made nuclear explosion occurred on July 16, 1945 at 5:50 am on the Trinity Test Site near Alamogordo, New Mexico in the United States, an area now known as the White Sands Missile Range. The event involved the full-scale testing of an implosion-type fission atomic bomb. In a memorandum to the U.S. Secretary of War, General Leslie Groves describes the yield as equivalent to 15,000 to 20,000 tons of TNT. Following this test, a uranium-gun type nuclear bomb (Little Boy) was dropped on the Japanese city of Hiroshima on August 6, 1945, with a blast yield of 15 kilotons; and a plutonium implosion-type bomb (Fat Man) on Nagasaki on August 9, 1945, with a blast yield of 21 kilotons. In the years following World War II, eight countries have conducted nuclear tests with 2475 devices fired in 2120 tests.
In 1963, the United States, Soviet Union, and United Kingdom signed the Limited Test Ban Treaty, pledging to refrain from testing nuclear weapons in the atmosphere, underwater, or in outer space. The treaty permitted underground tests. Many other non-nuclear nations acceded to the Treaty following its entry into force; however, two nuclear weapons states have not acceded: France, China
The primary application to date has been military (i.e. nuclear weapons), and the remainder of explosions include the following:
Only two nuclear weapons have been deployed in combat—both by the United States against Japan in World War II. The first event occurred on the morning of 6 August 1945, when the United States Army Air Forces dropped a uranium gun-type device, code-named "Little Boy", on the city of Hiroshima, killing 70,000 people, including 20,000 Japanese combatants and 20,000 Korean slave laborers. The second event occurred three days later when the United States Army Air Forces dropped a plutonium implosion-type device, code-named "Fat Man", on the city of Nagasaki. It killed 39,000 people, including 27,778 Japanese munitions employees, 2,000 Korean slave laborers, and 150 Japanese combatants. In total, around 119,000 people were killed in these bombings. (See Atomic bombings of Hiroshima and Nagasaki for a full discussion). Nuclear weapons are largely seen as a 'deterrent' by most governments; the sheer scale of the destruction caused by a nuclear weapon has prevented serious consideration of their use in warfare, rendering the concept of total war completely useless.
Since the Trinity test and excluding the combat use of nuclear weapons, mankind (those few nations with capability) has detonated roughly 1,700 nuclear explosions, all but 6 as tests. Of these, six were peaceful nuclear explosions. Nuclear tests are experiments carried out to determine the effectiveness, yield and explosive capability of nuclear weapons. Throughout the 20th century, most nations that have developed nuclear weapons had a staged test of them. Testing nuclear weapons can yield information about how the weapons work, as well as how the weapons behave under various conditions and how structures behave when subjected to a nuclear explosion. Additionally, nuclear testing has often been used as an indicator of scientific and military strength, and many tests have been overtly political in their intention; most nuclear weapons states publicly declared their nuclear status by means of a nuclear test.
Effects of nuclear explosionsEdit
The dominant effects of a nuclear weapon (the blast and thermal radiation) are the same physical damage mechanisms as conventional explosives, but the energy produced by a nuclear explosive is millions of times more per gram and the temperatures reached are in the tens of megakelvin. Nuclear weapons are quite different from conventional weapons because of the huge amount of explosive energy they can put out and the different kinds of effects they make, like high temperatures and nuclear radiation.
The devastating impact of the explosion does not stop after the initial blast, as with conventional explosives. A cloud of nuclear radiation travels from the epicenter of the explosion, causing an impact to life forms even after the heat waves have ceased.
- U.S. Department of Energy. "Trinity Site - World's First Nuclear Explosion". Energy.gov Office of Management. Retrieved 23 December 2016.
- Taylor, Alan (July 16, 2015). "70 Years Since Trinity: The Day the Nuclear Age Began". The Atlantic. Retrieved 23 December 2016.
- Groves, General Leslie (July 18, 1945). "The First Nuclear Test in New Mexico: Memorandum for the Secretary of War, Subject: The Test". United States War Department. PBS.org. Retrieved 23 December 2016.
- Yang, Xiaoping; North, Robert; Romney, Carl; Richards, Paul G. (August 2000), Worldwide Nuclear Explosions (PDF), retrieved 2013-12-31
- Malcolm Fraser and Tilman Ruff. 2015 is the year to ban nuclear weapons, The Age, February 19, 2015. | <urn:uuid:4140e958-c2e8-4839-a951-10d5a89578ce> | 3.140625 | 1,144 | Knowledge Article | Science & Tech. | 44.999643 | 95,645,215 |
Locked in Arctic Soils Into the Ocean, Researchers Say
The Arctic Ocean receives about ten percent of Earths river water and with it some 25 teragrams [28 million tons] per year of dissolved organic carbon that had been held in far northern bogs and other soils. Scientists had not known the age of the carbon that reaches the ocean: was it recently derived from contemporary plant material, or had it been locked in soils for hundreds or thousands of years and therefore not part of Earths recent carbon cycle?
Now, using carbon-14 data, scientists from the United States and Germany have been able to determine the approximate age of dissolved organic carbon in the Arctic for the first time. They report, in an article to be published this month in Geophysical Research Letters, that most of the carbon that reaches the ocean is relatively young at present, but that this could change. Warming of the Arctic, which has been documented in recent years, could affect northern peats, collectively one of the largest reservoirs of organic carbon on Earth. As the carbon-rich soils warm, the carbon is more susceptible to being transported to the ocean by rivers small and large, they say.
The researchers, headed by Ronald Benner of the University of South Carolina, studied four rivers in northern Russia and in Alaska, along with the Arctic Ocean itself. The carbon-14 dating method is not precise, because, for example, old and new dissolved organic carbon is typically mixed in a given sample, resulting in an average reading, and content of rivers varies by season as well. The scientists concentrated their study in periods of peak river discharge.
"Our results are not applicable to the sedimentary fraction of river discharge," Benner notes. "However, most of the organic carbon exported from land to the ocean is in dissolved form, and it is the dissolved components that track river water in the ocean."
River water tends to remain near the surface of the Arctic Ocean for five to 15 years, and the land-derived dissolved organic carbon from all sources and years is therefore mixed. Various samples gave radiocarbon average ages varying from 680 to 3,770 years, including both carbon from land-derived and marine sources. The researchers analyzed dissolved lignin phenols to determine the portion of a particular sample that had originated on land, as the compound is related only to terrestrial plant material.
The East Greenland Current is the major source of both Arctic Ocean water and its dissolved organic carbon component reaching the North Atlantic Ocean. The study concludes that the land- derived dissolved organic carbon reaching the Atlantic via this current is much younger than the marine component. In fact, up to half of it reaches the Atlantic, some three to 12 teragrams [three million to 13 million tons]. The fate of the young land-derived dissolved organic carbon in the Atlantic Ocean is uncertain, but there is no evidence of this material at lower latitudes in the Atlantic, the researchers say.
"This suggests most of the land-derived organic carbon ends up being oxidized to carbon dioxide and thus eventually cycles back into the atmosphere," says Benner. "If current warming trends in the Arctic continue, we can expect to see more of the old carbon now sequestered in northern soils enter the carbon cycle as carbon dioxide. This will act as a positive feedback, tending to enhance the greenhouse effect and accelerate global warming."
The research was funded by the U.S. National Science Foundation and the German Federal Ministry of Education and Research.
Harvey Leifert | AGU
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...
13.07.2018 | Event News
12.07.2018 | Event News
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13.07.2018 | Life Sciences | <urn:uuid:c2c55bb5-af8a-4bb2-a4c2-c6f8cb32e05e> | 3.703125 | 1,334 | Content Listing | Science & Tech. | 42.485152 | 95,645,216 |
Increasing rainfall has breathed new life into Lake Urmia which has been on the brink of drying up.
Iranian nano-companies operating in the field of water are seeking to secure a share of the lucrative market in East Asia.
The latest figures released by Iran Meteorological Organization suggest the 30-day period between April 21 and May 21 has been the rainiest month in Iran over the past ten years.
A group of Iranian scientists has managed to invent a new system that uses nanotechnology and renewable energies to treat wastewater.
Iranian Foreign Minister Mohammad Javad Zarif said Afghanistan has pledged to let Iran have its share of water from the Hirmand River and the supply for feeding Hamoon wetlands.
Iranian Science Minister Mansour Gholami has called for greater cooperation among Caspian Sea states to tackle its environmental issues as they develop into existential threats to the numerous and diverse ecosystems of the sea.
Lake Urmia in Iran’s West Azarbaijan province annually plays host to about 10,000 flamingos. However, in the migration seasons this number doubles and more of this species return to their habitat.
A number of Azerbaijan newts or Lake Urmia newts, a beautiful and rare type of salamander, have been observed and registered for the first time in Iran.
An Iranian entrepreneur has donated thousands of palm tree saplings to the villagers of Khuzestan Province in the country’s southwest in a bid to help the people cope with the severe dust pollution hitting the region.
An Iranian lawmaker has warned about the destruction of regional ecosystem by Turkey’s GAP (South Eastern Anatolian) Project, saying that the dam construction project is a Zionist plot. | <urn:uuid:43cc5b3d-e3c0-4bb9-b01a-60e7e67ab426> | 2.609375 | 352 | Content Listing | Science & Tech. | 31.877894 | 95,645,222 |
Chlorocypha radix Longfield, 1959
Western Red-tipped Jewel
- scientific: C. glauca (Selys, 1879) ssp. radix
Type locality: Ado-Ekiti, Nigeria
No diagnosis of this species that replaces C. glauca in western Africa is presently available. Please refer to the references provided.
Streams shaded by forest, but sometimes in clearings. Often with dead trunks or branches and probably submerged roots, coarse detritus and/or a sandy bottom. From 0 to 600 m above sea level, but mostly between 100 and 600.
Abdomen (dorsal 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.
- Longfield, C. (1959). The Odonata of N. Angola. Part II. Publicacoes culturais Companhia Diamantes Angola, 45, 13-42. [PDF file]
Citation: Dijkstra, K.-D.B (editor). African Dragonflies and Damselflies Online. http://addo.adu.org.za/ [2018-07-17]. | <urn:uuid:9d8c26a4-9ce1-4e4e-8b41-52a8b2f2774d> | 3.03125 | 335 | Knowledge Article | Science & Tech. | 73.319031 | 95,645,228 |
Chlorophyll fluorescence extraction from water-leaving radiance of algae-containing water through polarization
- 42 Downloads
When measuring reflectance spectra, it is very important to accurately extract chlorophyll fluorescence from elastic- scattering light in water-leaving radiance. The elastic scattering of light by water particles produces partially polarized light. In contrast, chlorophyll fluorescence in planktonic algae yields completely unpolarized light. These properties can be used to separate fluorescent signals from the water-leaving radiance and thus to determine chlorophyll concentration. The algal species Aureococcus anophagefferens was used to conduct a laboratory polarization experiment. For the tests, we used a field spectroradiometer and a polarizer; measurements were collected using two different observation modes. The chlorophyll fluorescence curve extracted through polarization shows an excellent match with the results obtained using the fluorospectro photometer for both measurement modes, suggesting that polarization-based chlorophyll fluorescence extraction may be feasible. The extracted fluorescence is more reliable at incident zenith angles ranging from 30° to 60°. For algae-containing water, the results improve with increasing chlorophyll concentration. This method could help improve chlorophyll concentration measurement and the remote-sensing detection of resulting harmful algae blooms.
Key wordschlorophyll fluorescence polarization technique water-leaving radiance extraction red shift
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This work was supported by the National Natural Science Foundation of China (Nos. 41406199, 41506197), the Program Foundation of Nanjing University of Information Science and Technology (No. KHYS1301), the Doctoral Scientific Research Foundation of Liaoning Province (No. 201501190), and the Fundamental Research Funds for the Central Universities (No. 3132015081).
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The tidewater goby is found along the Pacific coast of California from the Smith River in Del Norte County, south to Agua Hedionda Logoon in San Diego County. It is a small fish, rarely exceeding two inches in length. It's body is somewhat transparent-like, with blotches of brownish-gray colorations, and it has large pectoral fins, a blunt, elongate tail, and pelvis fins on the underside that are joined together into a sucker-like disk.
This species' habitat consists of brackish shallow lagoons and lower stream reaches with low salt-levels and where the water is fairly still but not stagnant. Reproduction occurs year round, although a great deal of spawning occurs in April and May. Males dig vertical burrows for females to deposit their eggs, and the larvae emerge nine to ten days later. All stages of the tidewater goby's life are spent in the same area unless forced into another marine environment during a strong storm. As larvae, they are usually found inshore using vegetation as shelter. As juveniles, these fish are believed to rest on the floor of the lagoons, feeding on small crustaceans such as copepods, amphipods, and mysid shrimp. Adults mainly feed on crustaceans, aquatic insects, and mollusks.
This species has declined because of loss of its coastal saltmarsh habitat due to coastal development activities resulting in salinity and pollution of the water. This species also competes with the yellowfin goby (Acanthogobius flavimanus), another fish that has been introduced in the area. The tidewater goby was listed as endangered in 1994 and is now legally protected. Also, the US FWS has developed a recovery plan aiming to guide conservation activities for the species.
Copyright Notice: This article is licensed under the GNU Free
Documentation License. It uses material from the Wikipedia article "Northern tidewater goby".
Tidewater Goby Facts Last Updated:
May 10, 2017
To Cite This Page:
Glenn, C. R. 2006. "Earth's Endangered Creatures - Tidewater Goby Facts" (Online).
Accessed 7/22/2018 at http://earthsendangered.com/profile.asp?sp=662&ID=9.
Need more Tidewater Goby facts? | <urn:uuid:40fbdd8b-0711-4590-a2cf-63072fd82a5a> | 3.8125 | 493 | Knowledge Article | Science & Tech. | 45.348672 | 95,645,299 |
Pictured is an image, captured by satellite, of the moon passing in front of Earth. This image may look photoshopped but it is 100 percent legitimate. NASA released the photograph, taken by a camera aboard the Deep Space Climate Observatory (DSCOVR) satellite. The image shows the fully illuminated “dark side” of the moon that is never visible from our humble planet.
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The LUNA experiment at the INFN Gran Sasso National Laboratory in Italy has observed a rare nuclear reaction that occurs in giant red stars, a type of star in which our sun will also evolve. This is the first direct observation of sodium production in these stars, one of the nuclear reactions that is fundamental for the formation of the elements that make up the universe. The study has been published in Physical Review Letters.
LUNA (Laboratory for Underground Nuclear Astrophysics) is a compact linear accelerator. It is the only one in the world installed in an underground facility, shielded against cosmic rays.
The experiment aims to study the nuclear reactions that take place inside stars where, like in an intriguing and amazing cosmic kitchen, the elements that make up matter are formed and then driven out by gigantic explosions and scattered as cosmic dust.
For the first time, this experiment has observed three "resonances" in the neon-sodium cycle responsible for sodium production in red giants and energy generation (the 22Ne(p,g)23Na. In the same way as in acoustics, a "resonance" is a particular condition that makes the reaction inside the star extremely likely.
LUNA recreates the energy ranges of nuclear reactions and, with its accelerator, goes back in time to one hundred million years after the Big Bang, to the formation of the first stars and the start of those processes that gave rise to mysteries we still do not fully understand, such as the huge variety in the quantities of the elements in the universe.
"This result is an important piece in the puzzle of the origin of the elements in the universe, which the experiment has been studying for the last 25 years", remarked Paolo Prati, spokesperson for the LUNA experiment.
"Stars generate energy and at the same time assemble atoms through a complex system of nuclear reactions. A very small number of these reactions have been studied in the conditions under which they occur inside stars, and a large proportion of those few cases have been observed with this accelerator".
LUNA uses a compact linear accelerator in which hydrogen and helium beams are accelerated and made to collide with a target (in this case, a neon isotope), to produce other particles. Special detectors obtain images of the products of the collisions and identify the reaction to be examined. These extremely rare processes can only be detected in conditions of cosmic silence. The rock surrounding the underground facility at the Gran Sasso National Laboratory shields the experiment against cosmic rays and protects its measurements.
LUNA is an international collaboration involving some 50 Italian, German, Scottish and Hungarian researchers from the National Institute for Nuclear Physics in Italy, the Helmholtz-Zentrum Dresden-Rossendorf in Germany, the MTA-ATOMKI in Hungary and the School of Physics and Astronomy of the University of Edinburgh in the UK.
Dr. Daniel Bemmerer
Institute of Radiation Physics at HZDR, Germany
Phone +49 351 260-23581
Prof. Paolo Prati
LUNA Spokesperson, INFN
Mobile: + 39 3493951491
INFN - Communications Office
Phone +39 06.6868162 | +39 345.2954623
LNGS - External Relations and Scientific Information
Phone +39 0862 437265/450
HZDR - Press officer
Phone +49 351 260-2450
Bautzner Landstr. 400, 01328 Dresden, Germany
The Helmholtz-Zentrum Dresden-Rossendorf (HZDR) conducts research in the sectors energy, health, and matter. It focuses its research on the following topics:
• How can energy and resources be used efficiently, safely, and sustainably?
• How can malignant tumors be visualized and characterized more precisely and treated effectively?
• How do matter and materials behave in strong fields and in the smallest dimensions?
Several large-scale research facilities provide unique research opportunities. These facilities are also accessible to external users.
The HZDR has been a member of the Helmholtz Association, Germany’s largest research organization, since 2011. It has four locations (Dresden, Leipzig, Freiberg, Grenoble) and employs about 1,100 people – approximately 500 of whom are scientists, including 150 doctoral candidates.
Dr. Christine Bohnet | Helmholtz-Zentrum Dresden-Rossendorf
First evidence on the source of extragalactic particles
13.07.2018 | Technische Universität München
Simpler interferometer can fine tune even the quickest pulses of light
12.07.2018 | University of Rochester
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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13.07.2018 | Materials Sciences
13.07.2018 | Life Sciences | <urn:uuid:4184e663-85cc-461f-b683-8ff2d412f82d> | 3.53125 | 1,538 | Content Listing | Science & Tech. | 38.1685 | 95,645,316 |
Washington: Planets rich in carbon, including so-called diamond planets, may lack oceans, according to a NASA study.
Our Sun is a carbon-poor star, and as result, our planet Earth is made up largely of silicates, not carbon. Stars with much more carbon than the Sun, on the other hand, are predicted to make planets chock full of carbon, and perhaps even layers of diamond.
By modelling the ingredients in these carbon-based planetary systems, the scientists determined they lack icy water reservoirs thought to supply planets with oceans.
"The building blocks that went into making our oceans are the icy asteroids and comets," said Torrence Johnson of NASA`s Jet Propulsion Laboratory in Pasadena, California, who presented the results at the American Astronomical Society Division of Planetary Sciences meeting in Denver.
"If we keep track of these building blocks, we find that planets around carbon-rich stars come up dry," he said.
Johnson and his colleagues said the extra carbon in developing star systems would snag the oxygen, preventing it from forming water.
"It`s ironic that if carbon, the main element of life, becomes too abundant, it will steal away the oxygen that would have made water, the solvent essential to life as we know it," said Jonathan Lunine of Cornell University, Ithaca, a collaborator on the research.
Researchers identify exoplanets by first looking for those that are situated within the "habitable zone" around their parent stars, which is where temperatures are warm enough for water to pool on the surface.
But even if a planet is found in this so-called "Goldilocks" zone, where oceans could, in theory, abound, is there actually enough water available to wet the surface?
Johnson and his team addressed this question with planetary models based on measurements of our Sun`s carbon-to-oxygen ratio.
Our Sun, like other stars, inherited a soup of elements from the Big Bang and from previous generations of stars, including hydrogen, nitrogen, silicon, carbon and oxygen.
These models accurately predict how much water was locked up in the form of ice early in the history of our solar system, billions of years ago, before making its way to Earth.
Comets and/or the parent bodies of asteroids are thought to have been the main water suppliers, though it is debated.
The objects are said to have begun their journey from far beyond Earth, past a boundary called the "snow line," before impacting Earth and depositing water deep in the planet.
When the researchers applied the planetary models to the carbon-rich stars, the water disappeared. "There`s no snow beyond the snow line," said Johnson.
"All rocky planets aren`t created equal. So-called diamond planets the size of Earth, if they exist, will look totally alien to us: lifeless, ocean-less desert worlds," said Lunine. | <urn:uuid:6efd3b08-48b5-4696-8fa7-20a8af6ef4e6> | 3.859375 | 599 | News Article | Science & Tech. | 38.51827 | 95,645,330 |
[caption id="attachment_42791" align="alignright" width="300" caption="During the 2005 and 2010 droughts, satellites detected decreased vegetation greennessor a lower Normalized Vegetation Index (NDVI)over the southern Amazon rainforest (orange and red regions). NDVI is derived from MODIS instruments on NASA's Terra and Aqua satellites. Image courtesy of Ranga Myneni, Jian Bi and NASA."]
AUSTIN, Texas A new study suggests the southern portion of the Amazon rainforest is at a much higher risk of dieback due to stronger seasonal drying than projections made by the climate models used in the latest report by the Intergovernmental Panel on Climate Change (IPCC).
If severe enough, the loss of rainforest could cause the release of large volumes of the greenhouse gas carbon dioxide into the atmosphere. It could also disrupt plant and animal communities in one of the regions of highest biodiversity in the world.
Using ground-based rainfall measurements from the past three decades, a research team led by Rong Fu, professor at The University of Texas at Austin's Jackson School of Geosciences, found that since 1979, the dry season in southern Amazonia has lasted about a week longer per decade. At the same time, the annual fire season has become longer. The researchers say the most likely explanation for the lengthening dry season is global warming.
"The dry season over the southern Amazon is already marginal for maintaining rainforest," says Fu. "At some point, if it becomes too long, the rainforest will reach a tipping point."
The new results are in stark contrast to forecasts made by climate models used by the IPCC. Even under future scenarios in which atmospheric greenhouse gases rise dramatically, the models project the dry season in the southern Amazon to be only a few to 10 days longer by the end of the century, and therefore the risk of climate change-induced rainforest dieback should be relatively low.
The report appears this week in the journal Proceedings of the National Academy of Sciences.
"The length of the dry season in the southern Amazon is the most important climate condition controlling the rainforest," says Fu. "If the dry season is too long, the rainforest will not survive.
To see why the length of the dry season is such a limiting factor, imagine there is heavier than usual rainfall during the wet season. The soil can only hold so much water and the rest runs off. The water stored in the soil at the end of the wet season is all that the rainforest trees have to last them through the dry season. The longer the dry season lasts, regardless of how wet the wet season was, the more stressed the trees become and the more susceptible they are to fire.
The researchers say the most likely explanation for the lengthening dry season in the southern Amazon in recent decades is human-caused greenhouse warming, which inhibits rainfall in two ways. First, it makes it harder for warm, dry air near the surface to rise and freely mix with cool, moist air above. And second, it blocks cold front incursions from outside the tropics that could trigger rainfall. The climate models used by the IPCC do a poor job representing these processes, which might explain why they project only a slightly longer Amazonian dry season, says Fu.
The Amazon rainforest normally removes the greenhouse gas carbon dioxide from the atmosphere, but during a severe drought in 2005, it released 1 petagram of carbon (about one-tenth of annual human emissions) to the atmosphere. Fu and her colleagues estimate that if dry seasons continue to lengthen at just half the rate of recent decades, the Amazon drought of 2005 could become the norm rather than the exception by the end of this century.
"Because of the potential impact on the global carbon cycle, we need to better understand the changes of the dry season over southern Amazonia," says Fu.
Some scientists have speculated that the combination of longer dry seasons, higher surface temperatures and more fragmented forests resulting from ongoing human-caused deforestation could eventually convert much of southern Amazonia from rainforest to savanna.
Earlier studies have shown that human-caused deforestation in the Amazon can alter rainfall patterns. But the researchers didn't see a strong signal of deforestation in the pattern of increasing dry season length. The dry season length increase was most pronounced in the southwestern Amazon while the most intense deforestation occurred in the southeastern Amazon.
Because the northwestern Amazon has much higher rainfall and a shorter dry season than the southern Amazon, Fu and others think it is much less vulnerable to climate change.
Fu's co-authors at The University of Texas at Austin's Jackson School of Geosciences are Lei Yin, Robert Dickinson, Lei Huang and Sudip Chakraborty. The team also includes Wenhong Li at Duke University; Paola A. Arias at Universidad de Antioquia in Colombia; Kátia Fernandes at Columbia University's International Research Institute for Climate and Society; Brant Liebmann at the National Oceanic and Atmospheric Administration (NOAA); Rosie Fisher at the National Center for Atmospheric Research; and Ranga Myneni at Boston University.
This work is supported by the National Science Foundation (AGS 0937400) and the NOAA Climate Program Office Modeling, Analysis, Prediction and Projection Program (NA10OAAR4310157).
The University of Texas at Austin is committed to transparency and disclosure of all potential conflicts of interest of its researchers. The university is not aware of any conflicts of interest for any of the team members. | <urn:uuid:0a0e731a-d50f-4f8d-804a-292a26578e25> | 3.453125 | 1,137 | News Article | Science & Tech. | 34.872306 | 95,645,337 |
The Model-View-Controller (MVC) pattern was introduced in 1970s. It is a software design pattern that splits an application into three main aspects : Model, View and Controller. Moreover, MVC pattern forces a separation of concerns within an application for example, separating data access logic and business logic from the UI.
Model - The "M" in "MVC"
The Model represents a set of classes that describes the business logic and data. It also defines business rules for how the data can be changed and manipulated.
Moreover, models in Asp.Net MVC, handles the Data Access Layer by using ORM tools like Entity Framework or NHibernate etc. By default, models are stored in the Models folder of the project.
The Model can be broken down into several different layers as given below:
Objects or ViewModel Layer
This layer contains simple objects or complex objects which are used to specify strongly-typed view. These objects are used to pass data from controller to strongly-typed view and vice versa. The classes for these objects can have specific validation rules which are defined by using data annotations. Typically, these classes have those properties which you want to display on corresponding view/page.
Data Access Layer
This layer provides objects to access and manipulate the database of your application. Typically, this layer is made by using ORM tools like Entity Framework or NHibernate etc.
This layer helps you to implement your business logic and validations for your application. This layer make use of Data Access Layer for persisting data into database. Also, this layer is directly invoked by the Controller to do processing on input data and sent back to view.
View - The "V" in "MVC"
The View is responsible for transforming a model or models into UI. The Model is responsible for providing all the required business logic and validation to the view. The view is only responsible for displaying the data, that is received from the controller as the result.
Moreover, views in Asp.Net MVC, handles the UI presentation of data as the result of a request received by a controller. By default, views are stored in the Views folder of the project.
Controller - The "C" in "MVC"
The Controller is responsible for controlling the application logic and acts as the coordinator between the View and the Model. The Controller receive input from users via the View, then process the user's data with the help of Model and passing the results back to the View.
Moreover, controllers in Asp.Net MVC, respond to HTTP requests and determine the action to take based upon the content of the incoming request. By default, controllers are stored in the Controllers folder of the project.
What do you think?
I hope you have got what is Model-View-Controller in Asp.Net MVC. I would like to have feedback from my blog readers. Your valuable feedback, question, or comments about this article are always welcome. | <urn:uuid:6333a3a9-fe55-465f-82e9-e64a90bc29d0> | 3.984375 | 614 | Knowledge Article | Software Dev. | 50.533584 | 95,645,368 |
PROFESSOR Stephen Hawking has said humanity has to find a way of leaving Earth or face the extinction of our species.
In the documentary, The Search for a New Earth, he said humans will soon find a way of visiting nearby star systems like Proxima b.
The British genius fears humanity will destroy itself through pollution and climate change, meaning we may one day need to find another place to live.
“I have no doubt we will eventually find ways of crossing the immense distances of space in just a few years,” he said, according to The Daily Star.
“One of our greatest strengths is embracing new ideas and evolving them into cutting-edge technologies.
“Our ingenuity will get us to Proxima b and in the next 100 years we will embark on our greatest ever adventure.”
He added: “We must have preparations in place within 100 years. Colonising Proxima b will be a challenge our species like nothing before.”
However, the physicist has previously said that alien species living way out in space pose a huge threat to our species.
Professor Stephen Hawking has become a notable doom-monger in recent years
“One day, we might receive a signal [from aliens] but we should be wary of answering back,” he said in the documentary Stephen Hawking’s Favourite Places.
“Meeting an advanced civilisation could be like Native Americans encountering Columbus. That didn’t turn out so well.”
THE TRUTH IS OUT THERE (MAYBE) Are aliens real? Here are the mysteries we need to solve in order to PROVE the existence of extraterrestrials
He claimed alien life could be “rapacious marauders roaming the cosmos in search of resources to plunder, and planets to conquer and colonise”.
His fears have not changed since he first spoke out about it on the Discovery Channel in 2010.
He said as he grew older he became more convinced humans were not alone.
“After a lifetime of wondering, I am helping to lead a new global effort to find out,” he said.
Professor Hawking has also warned Earth could become as hot as Venus as a result of climate change.
He told the BBC climate change could turn the planet into a hothouse, and Trump’s decision to pull out of the Paris Climate agreement to reduce CO2 levels could accelerate the threat.
“We are close to the tipping point, where global warming becomes irreversible,” he said.
“Trump’s action could push the Earth over the brink, to become like Venus, with a temperature of 250C, and raining sulphuric acid.”
Hawking also said humans may have to consider living on a different planet elsewhere if climate change ravages our own world.
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- the induction of an electromotive force by the motion of a conductor across a magnetic field or by a change in magnetic flux in a magnetic field.
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018
The New Dictionary of Cultural Literacy, Third Edition Copyright © 2005 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved. | <urn:uuid:1b97adec-68b8-4154-8ca9-f82bfb8378f1> | 2.9375 | 100 | Structured Data | Science & Tech. | 30.088893 | 95,645,413 |
Side view of a collapsed lava pit on the East Pacific Rise near 9°50N at a depth of 2,500 meters (about 8,000 feet). Two lava pillars in the center of the photo support a piece of the upper crust of the lava flow several inches thick.
Underside of a piece of lava from the East Pacific Rise showing drip structures or stalactites. The sample is about eight inches across, with individual lava drips of about one to two inches in length.
Photos ©Woods Hole Oceanographic Institution
Scientists studying the formation of the sea floor thousands of feet below the surface have a new theory for why there are so many holes and collapsed pits on the ocean bottom. In a recent article in the journal Nature, the researchers say the holes and pits of various sizes are probably formed by lava erupting onto the seafloor so quickly it traps water beneath it, forming bubbles of steam that eventually collapse as the water cools. The hardened crust then breaks, forming pock marks and glassy black plates of ocean crust with stalactites on their underside.
Findings by scientists at the Woods Hole Oceanographic Institution (WHOI) and colleagues may help explain the chemical differences between some seafloor lavas and increase understanding of deep-sea volcanic processes. The report also offers new insights into microbes living inside the ocean crust, an area known as the deep biosphere. No one has witnessed an undersea volcanic eruption, although researchers diving in the three-person submersible ALVIN have visited sites of very recent eruptions that were colonized almost immediately by exotic life forms.
Geologists Daniel Fornari and Deborah Smith of WHOI, along with lead author Michael Perfit of the University of Florida and colleagues from the University of Leeds in the United Kingdom, University of Hawaii and the US Geological Survey, report that up to now, scientists thought there was very little interaction between the very cold sea water at the ocean floor several miles deep and the molten lava that erupts to form new crust. Geologists didn’t think the lava, despite reaching temperatures well over 2,000 degrees Fahrenheit, could heat the seawater enough to form steam because of the intense pressure at such great depth.
Shelley Dawicki | WHOI
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
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20.07.2018 | Power and Electrical Engineering
20.07.2018 | Information Technology
20.07.2018 | Materials Sciences | <urn:uuid:eab381fd-ba16-4906-877f-7ec72685230b> | 4.03125 | 1,033 | Content Listing | Science & Tech. | 39.971626 | 95,645,415 |
Spectacular View of Betelgeuse
The Atacama Large Millimeter Array (ALMA) has captured a spectacular view of Betelgeuse. Also known as Alpha Orionis, Betelgeuse is a red giant star located within the visual bounds of the constellation Orion. This is one of very few stars large enough to be seen in a picture as more than simply a blip of light.
Betelgeuse is 650 light years away and only rotates once every 8.4 years. It is also an incredibly large star at 6 AU (half a billion miles) in diameter. The first measurement of Betelgeuse was taken by Albert Michelson in 1920 using the Mount Wilson 100-inch. The initial diameter taken came in at 240 million miles, only about half of today’s accepted diameter. When seen from earth, however, the star only appears to be 50 milliarcseconds across. Betelgeuse’s current apparent diameter is one of the largest of any star in our night sky, which is only beaten by R Doradus (57 milliarcseconds across).
In the image captured by ALMA, an asymmetrical bubble is seen rolling across Betelgeuse’s surface. Infrared surveys have shown scientists that Betelgeuse is actually surrounded by a bow-shock, which is created by the stellar wind coming from Betelgeuse and the gas in the interstellar medium interacting with each other. This will one day result in a brilliant light show to be seen from our very own planet when the star ultimately dies.
At eight million years old, Betelgeuse is quite a young star, considering that our own Sun has been around for 4.6 billion years. Although Betelgeuse is considered a young star, it is destined to die in a massive supernova in the next few thousand years or so. Luckily for us, Betelgeuse’s death will be out of the supernova “kill zone” by 25 to 100 light years. The massive star’s death will serve as an important nearby supernova candidate (along with the star, Spica, at 250 light years away) for astronomers’ future studies of the anatomy of a supernova explosion.
It is entirely possible that this supernova could have already occurred and is making its way to our vision through 650 light years of space. Regardless of when it arrives, Betelgeuse will serve as an important scientific study and teach us more about the death of stars! #GetExcitedSU | <urn:uuid:cfbea911-80e7-4d97-9c4a-3dda0be99ee5> | 3.828125 | 524 | News (Org.) | Science & Tech. | 48.732415 | 95,645,421 |
To obtain a lightweight and high-strength wood sandwich structure, a wooden lattice sandwich cell element was designed in combination with a pyramid-type structure. After inserting glue to prepare the cell unit, the influence of panel thickness and core diameter on the unit cell force was analyzed and compared under the condition of flat pressure. Under the condition of flat pressure, the specific strength of the unit cell was higher than that of the specific strength of the composition material, and the unit cell may be regarded as a structure with high specific strength. Theoretical predictions, simulation analysis, and experimental tests demonstrated that the structure compressive capacity depended on the diameter of the core when the core length was set. The larger the diameter of the core is, the stronger the bearing capacity of the unit cell will be. When the diameter of the core is constant, the longer the core length is, the weaker the bearing capacity of the unit cell will be. The simulation analysis was in agreement with the experimental test results, indicating that the destruction of the structure was mainly caused by the failure of the core. | <urn:uuid:00b1d671-d640-40b0-b97c-4f15de2242a8> | 3.09375 | 215 | Academic Writing | Science & Tech. | 29.1825 | 95,645,433 |
The color representation of the digamma function,
, in a rectangular region of the complex plane
In mathematics, the digamma function is defined as the logarithmic derivative of the gamma function:
It is the first of the polygamma functions.
The digamma function is often denoted as ψ0(x), ψ(0)(x) or Ϝ (the uppercase form of the archaic Greek consonant digamma meaning double-gamma).
Relation to harmonic numbers
The gamma function obeys the equation
Taking the derivative with respect to z gives:
Dividing by Γ(z + 1) or the equivalent zΓ(z) gives:
Since the harmonic numbers are defined as
the digamma function is related to it by:
where Hn is the nth harmonic number, and γ is the Euler–Mascheroni constant. For half-integer values, it may be expressed as
Harmonic Mean Value Inequality
Inspired by the harmonic mean value inequality for the classical gamma function, Horzt Alzer and Graham Jameson proved, among other things, a harmonic mean-value inequality for the digamma function:
Equality holds if and only if
If the real part of x is positive then the digamma function has the following integral representation
This may be written as
which follows from Leonhard Euler's integral formula for the harmonic numbers.
Infinite product representation
The function is an entire function, and it can be represented by the infinite product
Here is the kth zero of (see below), and is the Euler–Mascheroni constant.
The digamma function can be computed in the complex plane outside negative integers (Abramowitz and Stegun 6.3.16), using
This can be utilized to evaluate infinite sums of rational functions, i.e.,
where p(n) and q(n) are polynomials of n.
Performing partial fraction on un in the complex field, in the case when all roots of q(n) are simple roots,
For the series to converge,
otherwise the series will be greater than the harmonic series and thus diverge. Hence
With the series expansion of higher rank polygamma function a generalized formula can be given as
provided the series on the left converges.
The digamma has a rational zeta series, given by the Taylor series at z = 1. This is
which converges for |z| < 1. Here, ζ(n) is the Riemann zeta function. This series is easily derived from the corresponding Taylor's series for the Hurwitz zeta function.
The Newton series for the digamma, sometimes referred to as Stern series, reads
k) is the binomial coefficient. It may also be generalized to
where m = 2,3,4,...
The digamma function satisfies a reflection formula similar to that of the gamma function:
Recurrence formula and characterization
The digamma function satisfies the recurrence relation
Thus, it can be said to "telescope" 1 / x, for one has
where Δ is the forward difference operator. This satisfies the recurrence relation of a partial sum of the harmonic series, thus implying the formula
where γ is the Euler–Mascheroni constant.
More generally, one has
Another series expansion is:
where are the Bernoulli numbers.
Actually, ψ is the only solution of the functional equation
that is monotonic on ℝ+ and satisfies F(1) = −γ. This fact follows immediately from the uniqueness of the Γ function given its recurrence equation and convexity restriction. This implies the useful difference equation:
Some finite sums involving the digamma function
There are numerous finite summation formulas for the digamma function. Basic summation formulas, such as
are due to Gauss. More complicated formulas, such as
are due to works of certain modern authors (see e.g. Appendix B in Blagouchine (2014)).
Gauss's digamma theorem
For positive integers r and m (r < m), the digamma function may be expressed in terms of Euler's constant and a finite number of elementary functions
which holds, because of its recurrence equation, for all rational arguments.
Computation and approximation
According to the Euler–Maclaurin formula applied to
the digamma function for x, a real number, can be approximated by
which is the beginning of the asymptotical expansion of ψ(x). The full asymptotic series of this expansions is
where Bk is the kth Bernoulli number and ζ is the Riemann zeta function. Although the infinite sum does not converge for any x, this expansion becomes more accurate for larger values of x and any finite partial sum cut off from the full series. To compute ψ(x) for small x, the recurrence relation
can be used to shift the value of x to a higher value. Beal suggests using the above recurrence to shift x to a value greater than 6 and then applying the above expansion with terms above x14 cut off, which yields "more than enough precision" (at least 12 digits except near the zeroes).
As x goes to infinity, ψ(x) gets arbitrarily close to both ln(x − 1/2) and ln x. Going down from x + 1 to x, ψ decreases by 1 / x, ln(x − 1/2) decreases by ln (x + 1/2) / (x − 1/2), which is more than 1 / x, and ln x decreases by ln (1 + 1 / x), which is less than 1 / x. From this we see that for any positive x greater than 1/2,
or, for any positive x,
The exponential exp ψ(x) is approximately x − 1/2 for large x, but gets closer to x at small x, approaching 0 at x = 0.
For x < 1, we can calculate limits based on the fact that between 1 and 2, ψ(x) ∈ [−γ, 1 − γ], so
From the above asymptotic series for ψ, one can derive an asymptotic series for exp(−ψ(x)). The series matches the overall behaviour well, that is, it behaves asymptotically as it should for large arguments, and has a zero of unbounded multiplicity at the origin too.
This is similar to a Taylor expansion of exp(−ψ(1 / y)) at y = 0, but it does not converge. (The function is not analytic at infinity.) A similar series exists for exp(ψ(x)) which starts with
If one calculates the asymptotic series for ψ(x+1/2) it turns out that there are no odd powers of x (there is no x−1 term). This leads to the following asymptotic expansion, which saves computing terms of even order.
The digamma function has values in closed form for rational numbers, as a result of Gauss's digamma theorem. Some are listed below:
Moreover, by the series representation, it can easily be deduced that at the imaginary unit,
Roots of the digamma function
The roots of the digamma function are the saddle points of the complex-valued gamma function. Thus they lie all on the real axis. The only one on the positive real axis is the unique minimum of the real-valued gamma function on ℝ+ at x0 = 632144968... 1.461. All others occur single between the poles on the negative axis:
Already in 1881, Charles Hermite observed that
holds asymptotically. A better approximation of the location of the roots is given by
and using a further term it becomes still better
which both spring off the reflection formula via
and substituting ψ(xn) by its not convergent asymptotic expansion. The correct second term of this expansion is 1 / 2n, where the given one works good to approximate roots with small n.
Another improvement of Hermite's formula can be given:
Regarding the zeros, the following infinite sum identities were recently proved by István Mező and Michael Hoffman
In general, the function
can be determined and it is studied in detail by the cited authors.
The following results
also hold true.
Here γ is the Euler–Mascheroni constant.
The digamma function appears in the regularization of divergent integrals
this integral can be approximated by a divergent general Harmonic series, but the following value can be attached to the series
- ^ a b
Abramowitz, M.; Stegun, I. A., eds. (1972). "6.3 psi (Digamma) Function.". Handbook of Mathematical Functions with Formulas, Graphs, and Mathematical Tables (10th ed.). New York: Dover. pp. 258–259.
- ^ Weisstein, Eric W. "Digamma function". MathWorld.
- ^ Alzer, Horst; Jameson, Graham (2017). "A harmonic mean inequality for the digamma function and related results" (PDF). Rendiconti del Seminario Matematico della Università di Padova. 70 (201): 203–209. doi:10.4171/RSMUP/137-10. ISSN 0041-8994. LCCN 50046633. OCLC 01761704.
- ^ a b c d Mező, István; Hoffman, Michael E. (2017). "Zeros of the digamma function and its Barnes G-function analogue" (28): 846–858. doi:10.1080/10652469.2017.1376193.
- ^ Nörlund, N. E. (1924). Vorlesungen über Differenzenrechnung. Berlin: Springer.
- ^ a b Blagouchine, Ia. V. (2018). "Three Notes on Ser's and Hasse's Representations for the Zeta-functions". Integers (Electronic Journal of Combinatorial Number Theory). 18A: 1–45. arXiv:1606.02044 . Bibcode:2016arXiv160602044B.
- ^ R. Campbell. Les intégrales eulériennes et leurs applications, Dunod, Paris, 1966.
- ^ H.M. Srivastava and J. Choi. Series Associated with the Zeta and Related Functions, Kluwer Academic Publishers, the Netherlands, 2001.
- ^ Blagouchine, Iaroslav V. (2014). "A theorem for the closed-form evaluation of the first generalized Stieltjes constant at rational arguments and some related summations". Journal of Number Theory. Elsevier. 148: 537–592. arXiv:1401.3724 . doi:10.1016/j.jnt.2014.08.009.
- ^ Bernardo, José M. (1976). "Algorithm AS 103 psi(digamma function) computation" (PDF). Applied Statistics. 25: 315–317.
- ^ Beal, Matthew J. (2003). Variational Algorithms for Approximate Bayesian Inference (PDF) (PhD thesis). The Gatsby Computational Neuroscience Unit, University College London. pp. 265–266.
- ^ If it converged to a function f(y) then ln(f(y) / y) would have the same Maclaurin series as ln(1 / y) − φ(1 / y). But this does not converge because the series given earlier for φ(x) does not converge.
- ^ Hermite, Charles (1881). "Sur l'intégrale Eulérienne de seconde espéce,". Journal für die reine und angewandte Mathematik (90): 332–338.
- A047787 psi(1/3), A200064 psi(2/3), A020777 psi(1/4), A200134 psi(3/4), A200135 to A200138 psi(1/5) to psi(4/5). | <urn:uuid:bceb359b-d29b-43c0-bfc1-e4467696b00a> | 3.125 | 2,672 | Knowledge Article | Science & Tech. | 64.175543 | 95,645,435 |
|A purple-striped jelly (Chrysaora colorata) on exhibit at Monterey Bay Aquarium|
The purple-striped jelly (Chrysaora colorata) is a species of jellyfish that exists primarily off the coast of California in Monterey Bay. The bell (body) of the jellyfish is up to 70 cm (27.6 inches or 2.3 feet) in diameter, typically with a radial pattern of stripes. The tentacles vary with the age of the individual, consisting typically of eight marginal long dark arms, and four central frilly oral arms. It is closely studied by scientists due to not much being known about their eating habits.
The purple striped jelly is also known as the purple-striped sea nettle and the mauve stinger. When it is extremely young, it has a pinkish color and its tentacles are long and dark maroon. At the adult stage the dark maroon color of the tentacles starts to fade and the purple appears as stripes on the bell. At a young age the adults' four frilly oral arms will become longer. When the jellyfish starts to get older the tentacles thicken and the purple stripes start to darken and the tentacles start to look pale, its oral arms like to disappear. They are known to feed on a variety of organisms including Cladocera, Appendicularia, Copepoda, Hydromedusae, Siphonophora, and fish eggs. When the prey touches a marginal tentacle, stingers are immediately discharged to paralyze prey and marginal tentacle bends inward to the nearest oral arm. The oral arm is used to transport prey to the gastrovascular cavity (GVC) and to catch motionless prey. The sting of this jellyfish is extremely painful to humans but is rare.
- "WoRMS - World Register of Marine Species - Chrysaora colorata (Russell, 1964)". www.marinespecies.org. Retrieved 2018-01-30.
- The JelliesZone - Jellyfish & Other Gelatinous Zooplankton: Chrysaora colorata Archived 2008-02-24 at the Wayback Machine., accessed March 15, 2008
- "Purple-striped jelly". Monterey Bay Aquarium. Retrieved 3 April 2010.
- "Shedd Aquarium fact sheet" (PDF).
|This subphylum Medusozoa related article is a stub. You can help Wikipedia by expanding it.| | <urn:uuid:995f058a-89c3-4fbd-a7a1-671d25d392a4> | 3.234375 | 518 | Knowledge Article | Science & Tech. | 51.246754 | 95,645,446 |
Whistling tree frogs, Litoria verreauxii, are one of the species monitored around Canberra for their response to climate change.
Catching the eye/flickr
Climate change can seem far removed from our everyday lives, which is why a citizen science program measuring how frogs are dealing with a warming world is so important.
Christian Wilkinson / shutterstock
We used 11 different satellite missions to track Antarctica’s contribution to rising sea levels.
Long’s Peak framed by rock outcrop, Rocky Mountain National Park, Colorado.
Scientists have long thought most nitrogen in Earth's ecosystems comes from the air, but new research shows it also is released as rocks weather. This could boost plant growth and help sequester carbon – but not fast enough to avert climate change, as some pundits have claimed.
Scientists on Arctic sea ice in the Chukchi Sea, surrounded by melt ponds, July 4, 2010.
Climate change is transforming the Arctic, with impacts on the rest of the planet. A geographer explains why he once doubted that human actions were causing such shifts, and what changed his mind.
Dust storms in the Gulf of Alaska, captured by NASA’s Aqua satellite.
There are more satellites than ever before, orbiting Earth and collecting data that's crucial for scientists. Why do some nations choose not to share that data openly?
Some information on the climate has been obscured.
Despite scientists' initial concerns, federal climate change data sets are still available. But other documents and web pages have changed over the last year.
MiMA: an open source way to model the climate.
The creation of climate models with open source code, available for anyone to use, has improved scientific collaboration and helped research get more efficient.
kwest / shutterstock
Long-term climate modelling may appear to focus on the impossibly far future. But the full impact of some climate processes won't be apparent for centuries.
rawpixel.com / shutterstock
Research can be spun, within hours, into a story of past failure. In fact, it's a case of continuous improvement.
Trust is everything.
Politicians are always being told to trust what climate scientists are telling them. But can you have too much of a good thing? What happens when the exchange of ideas becomes too cosy?
The continent is home to 12 million penguins…and not much else.
Andrew Peacock, footloosefotography.com
The Antarctic Treaty was signed 58 years ago today, protecting the continent for peace and science.
By the age of 16, most teenagers have already made up their mind about climate change.
Players in the climate science game 'CO2peration' become a particle of sunlight, and travel on a journey to find out why we have liquid water at Earth’s surface.
underworld / shutterstock
Some claim that scientists avoid publishing results that go against the consensus on man-made climate change. But this is simply untrue.
The Day After Tomorrow’s apocalyptic depiction of climate change is a little embellished. But such storylines can ignite conversations with people that mainstream science fails to reach.
20th Century Fox
Climate scientists often bombard their audiences with facts and figures - a method of communication that often doesn't work. Perhaps this is where cli-fi can step in, with its compelling characters and just slightly embellished science.
Who set the guardrails on global temperature rise?
More and more research shows that we are likely to pass the 2 degree Celsius temperature limit much of the world has agreed on. Where did that limit come from, and what if we miss it?
Dan Bach Kristensen / shutterstock
The ice sheet is melting and permafrost is thawing. What's happening in Greenland will speed up climate change across the world.
When Tony Abbott went too far in his advocacy for the coal industry, his government faced a public backlash.
While climate denialism impedes policymaking in both the US and Australia, there are key differences in their political and public cultures.
In 2013, pro-science supporters rallied before a Texas Board of Education public hearing on proposed new science textbooks.
AP Photo/Eric Gay
Thirty years after the Supreme Court ruled that creationism cannot be required in schools, 'creation science' is still taught in some schools. What are the implications for climate education?
Average carbon dioxide concentrations, Oct. 1 -
Nov. 11, 2014, measured by the Orbiting Carbon Observatory-2 satellite.
Why use satellites to study Earth's climate? Researchers leading a new mission explain how images from space will help them analyze which parts of the Americas soak up the most carbon.
Nobody can observe events in the future so to study climate change, scientists build detailed models and use powerful supercomputers to simulate conditions, such as the global water vapor levels seen here, and to understand how rising greenhouse gas levels will change Earth’s systems.
People worry Washington is losing respect for science and even the centuries-old scientific method. Two climate scientists explain how science can be done when talking about the future. | <urn:uuid:e1a90236-99f0-4680-b2bb-6fdb3462a00b> | 3.359375 | 1,052 | Content Listing | Science & Tech. | 45.594614 | 95,645,453 |
United States of Energy
Learn more about Teaching Climate Literacy and Energy Awareness»
See how this Animation supports the Next Generation Science Standards»
High School: 2 Disciplinary Core Ideas, 1 Science and Engineering Practice
About Teaching Climate Literacy
4.1 Humans transfer and transform energy.
4.5 Electricity generation.
4.7 Different sources of energy have different benefits and drawbacks.
6.3 Demand for energy is increasing.
6.8 Calculating and monitoring energy use.
Notes From Our Reviewers
The CLEAN collection is hand-picked and rigorously reviewed for scientific accuracy and classroom effectiveness.
Read what our review team had to say about this resource below or learn more about
how CLEAN reviews teaching materials
Teaching Tips | Science | Pedagogy |
- Probably best used as an introduction to fuels and energy usage.
- There are a lot of graphics presented in a long list. The map of the United States regional energy resources is the most useful to use in energy-related activities.
About the Science
- This series of visualizations shows a breakdown of energy sources by state, type, change over time, usage, and source. It gives a good overview of how energy use has risen since 1949 in the US, how more energy is now imported since 1956 than produced, and how different states create and source their energy.
- Visualization may be outdated - this is from 2011, and much has changed, particularly in the renewable sector and natural gas.
Comments from expert scientist:
The resource provides a really neat summary of the energy portfolio for every State. Data are detailed and the aesthetic of the visualization format is outstanding.
Is nuclear a really 'clean' energy as stated in one of the plots in the resource? This is true if considering carbon emissions only.
Some of the data in the version 1 of the resource are 15 years old. Data used in the version 2 are more recent.
About the Pedagogy
- A good way to introduce use of fuels and energy sources in the US.
- Visually appealing.
- Does contain a lot of graphics and basic information.
Next Generation Science Standards See how this Animation supports:
Disciplinary Core Ideas: 2
HS-ESS3.A1:Resource availability has guided the development of human society.
HS-ESS3.A2:All forms of energy production and other resource extraction have associated economic, social, environmental, and geopolitical costs and risks as well as benefits. New technologies and social regulations can change the balance of these factors. | <urn:uuid:a39f332f-09eb-4727-9170-ea6f1b71a5ee> | 3.625 | 525 | Content Listing | Science & Tech. | 38.370072 | 95,645,456 |
Population biology of alpine plants
Extreme climate conditions (i.e., a cold winter and a short summer with significant fluctuations in temperature between day and night) is the main stress factor in alpine habitats. Consequently, alpine plants must adapt their age population structure and growth strategy to the fluctuating severe environment. In general, the aim of alpine plants’ adaptations is to minimise the risk of a sudden local extinction under more or less continuously severe external conditions.
KeywordsSeed Bank Soil Seed Bank Alpine Plant Aboveground Vegetation Persistent Seed Bank
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Interaction domain on proteins that modulate this potent hormone allows them to stack back-to-front like button magnets
Wikipedia lists 65 adjectives that botanists use to describe the shapes of plant leaves. In English (rather than Latin) they mean the leaf is lance-shaped, spear-shaped, kidney-shaped, diamond shaped, arrow-head-shaped, egg-shaped, circular, spoon-shaped , heart-shaped, tear-drop-shaped or sickle-shaped — among other possibilities.
Graduate student David Korasick commuted between the Strader Lab, which specializes in genetics, and the Jez Lab, which has expertise in structural biology, to learn how plants control the effects of the master hormone auxin.
How does the plant “know” how to make these shapes? The answer is by controlling the distribution of a plant hormone called auxin, which determines the rate at which plant cells divide and lengthen.
But how can one molecule make so many different patterns? Because the hormone’s effects are mediated by the interplay between large families of proteins that either step on the gas or put on the brake when auxin is around.
In recent years as more and more of these proteins were discovered, the auxin signaling machinery began to seem baroque to the point of being unintelligible.
Now the Strader and Jez labs at Washington University in St. Louis have made a discovery about one of the proteins in the auxin signaling network that may prove key to understanding the entire network.
In the March 24 issue of the Proceedings of the National Academy of Sciences they explain that they were able to crystallize a key protein called a transcription factor and work out its structure. The interaction domain of the protein, they learned, folds into a flat paddle with a positively charged face and a negatively charged face. These faces allow the proteins to snap together like magnets, forming long chains, or oligomers.
We have some evidence that proteins chain in plant cells as well as in solution, said senior author Lucia Strader, PhD, assistant professor of biology and an auxin expert. By varying the length of these chains, plants may fine-tune the response of individual cells to auxin to produce detailed patterns such as the toothed lobes of the cilantro leaf.
Sculpting leaves is just one of many roles auxin plays in plants. Among other things the hormone helps make plants bend toward the light, roots grow down and shoots grow up, fruits develop and fruits fall off.
“The most potent form of the hormone is indole-3-acetic acid, abbreviated IAA, and my lab members joke that IAA really stands for Involved in Almost Everything,” Strader said.
The backstory here is that whole families of proteins intervene between auxin and genes that respond to auxin by making proteins. In the model plant Aribidopsis thaliana these include 5 transcription factors that activate genes when auxin is present (called ARFs) and 29 repressor proteins that block the transcription factors by binding to them (Aux/IAA proteins). A third family marks repressors for destruction.
“Different combinations of these proteins are present in each cell,” said Strader. “On top of that, some combinations interact more strongly than others and some of the transcription factors also interact with one another.”
In an idle moment David Korasick, a graduate fellow in the Strader and Jez labs and first author on the PNAS article, did a back-of-the-envelope calculation to put a number on the complexity of the system they were trying to understand. From a strictly mathematical point of view there are 3,828 possible combinations of the auxin-related Arabidopsis proteins. That is assuming interactions involve only one of each type of protein; if multiples are possible, the number, of course, explodes.
To make any headway, Strader said, we had a better understanding of how these proteins interact. The rule in protein chemistry is the opposite of the one in design: instead of form following function, function follows form.
So to figure out a protein’s form — the way it folds in space — they turned to the Jez lab, which specializes in protein crystallography, essentially a form of high-resolution microscopy that allows protein structures to be visualized at the atomic level.
Korasick had the job of crystallizing ARF7, a transcription factor that helps, Arabidopsis bend toward the light. With the help of Joseph Jez, PhD, associate professor of biology, Corey Westfall, and Soon Goo Lee), Korasick cut “floppy bits” off the protein that might have made it hard to crystallize, leaving just the part of the protein where it interacts with repressor molecules.
After he had that construct, crystallization was remarkably fast. He set up his first drops in solution wells on the 4th of July. The protein crystallized with a fuss, and he ran the crystals up to the Advanced Photon Source at the Argonne National Laboratory outside Chicago. By August 1 he had the diffraction data he needed to solve the protein’s structure.
The previous model for the interaction between a repressor and a transcription factor – a model that had stood for 15 years, Strader said– was that the repressor lay flat on the transcription factor, two domains on the repressor matching up with the corresponding two domains on the transcription factor.
The structural model Korasick developed showed that the two domains fold together to form a single domain, called a PB1 domain. A PB1 domain is a protein interaction module that can be found in animals and fungi as well as plants.
The repressor proteins, which are predicted to have PB1 domains identical to that of the ARF transcription factor, then stick to one or the other side of the transcription factor’s PB1 domain, preventing it from doing its job. Experiments showed that there had to be a repressor protein stuck to both faces of the transcription factor’s PB1 domain to repress the activity of auxin.
This means the model, which pairs a single repressor protein with a single transcription factor, is wrong, Strader said.
“Nor can we limit the interactions to just two,” she said. “It could be hundreds for all we know.“
In Korasick’s crystal five of the ARF7 PB1 domains stuck to one another, forming a pentamer.
“I like to think of the PB1 domains as magnets, “ Strader said. “Like magnets, they can stick together, back-to-front, to form long chains.”
“But we have to put an asterisk next to that,” Korasick said, “because it’s possible it’s an artifact of crystallography and doesn’t work that way in living plants.“
But both Strader and Korasick suspect that it does. Strader points out that the complexity of the auxin signaling system has increased over evolutionary time as plants became fancier. A simple plant like the moss Physcomitrella patens has fewer signaling proteins than a complicated plant like soybean.
“Probably what that’s saying is that it’s really, really important for a plant to be able to modulate auxin signaling, to have the right amount in each cell, to balance positive and negative growth,” Korasick said.
“The difference between plants and animals,” said Strader, “is that plants have rigid cell walls. So when a plant cell decides to divide itself or length itself, that’s a permanent decision, which is why it’s so tightly controlled.“
Diana Lutz | newswise
Scientists uncover the role of a protein in production & survival of myelin-forming cells
19.07.2018 | Advanced Science Research Center, GC/CUNY
NYSCF researchers develop novel bioengineering technique for personalized bone grafts
18.07.2018 | New York Stem Cell 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
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Quasi-periodic variation in sea-surface temperature, precipitation, and sea-level pressure in the equatorial Pacific known as the El Niño &8211; Southern Oscillation (ENSO) is an important mode of interannual variability in global climate. A collapse of the tropical Pacific onto a state resembling a so-called &8216;permanent El Niño&8217;, with a preferentially warmed eastern equatorial Pacific, flatter thermocline, and reduced interannual variability, in a warmer world is predicted by prevailing ENSO theory. If correct, future warming will be accompanied by a shift toward persistent conditions resembling El Niño years today, with major implications for global hydrological cycles and consequent impacts on socioeconomic and ecological systems. However, much uncertainty remains about how interannual variability will be affected. Here, we present multi-annual records of climate derived from growth increment widths in fossil bivalves and co-occurring driftwood from the Antarctic peninsula that demonstrate significant variability in the quasi-biennial and 3&8211;6 year bands consistent with ENSO, despite early Eocene (&8764;50 Mya) greenhouse conditions with global average temperature &8764;10 degrees higher than today. A coupled climate model suggests an ENSO signal and teleconnections to this region during the Eocene, much like today. The presence of ENSO variation during this markedly warmer interval argues for the persistence of robust interannual variability in our future greenhouse world.
Mendeley saves you time finding and organizing research
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Authors: Nainan K. Varghese
Abstract: This article attempts to give a simple and logical explanation to tidal mechanism, based on a radically different dynamics, presented in book ‘MATTER Re-examined)’ . Tides are caused by (accelerating) actions of external efforts on a linearly moving spinning-macro body. Each external effort alters shape of spinning macro body, separately, to produce its own set of tides. Change in shape of a spinning macro body, rather than displacement of its parts, cause tides. Displacement of ocean water in the direction of moving tide is superficial and it cannot produce tidal drag on earth’s solid core body.
Comments: 9 Pages. Originally published in General Science Journal
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Application of Nuclear Calculation Methods to the Planning of Radiation Treatment with Gamma Rays
Computer programs have been developed in recent years for the design of nuclear reactors with improved shielding; these can be applied in radiology to provide a theoretical basis for earlier experimental work and semi-empirical methods.
The Stuttgart PLK program, originally developed to determine heat sources and equivalent doses of mixed neutron and gamma radiation, was adapted to enable calculation by computer of the production of secondary electrons by gamma radiation in the tissues. Where penetration of secondary electrons can be neglected (X-ray and 60Co radiation), the desired local distribution of the energy dose is found directly; where it cannot (betatron gamma radiation), the necessary information about the source of secondary electrons is obtained. Three examples are given to illustrate the efficiency of the method: a layer of homogeneous tissue, thigh and head irradiation. Hard and soft X-rays, cobalt gamma rays and betatron bremsstrahlen were programmed at energy maxima of 10, 30 and 50 MeV.
Keywords60CO Radiation Early Experimental Work Head Irradiation Mixed Neutron Iiber Eine
Anwendung kerntechnischer Berechnungsmethoden für Gammastrahlen bei der Bestrahlungsplanung
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- 1.Penny, S. K., Trubey, D. K., Emmett, M. B.: Ogre. A Monte Carlo System for Gamma Ray Transport Studies. ORNL-3805, 1966.Google Scholar
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Streamlined sharks are legendary for their effortless swimming. George Lauder from Harvard University, USA, explains that the fish have long inspired human engineers, but more recently attention has focused on how the fish's remarkable skin boosts swimming.
Coated in razor sharp tooth-like scales, called denticles, the skin is thought to behave like the dimples on a golf ball, disturbing the flow of water over the surface to reduce the drag. But something didn't quite sit right with Lauder. 'All of the shark skin studies were done on flat shark skin mimics that were held straight and immovable. But shark skin moves', recalls Lauder.
So, when Masters student Johannes Oeffner joined his lab, Lauder suggested that they take a look at the fluid dynamics of shark skin and its analogues to find out how the fish's motion affects fluid flowing over the rough surface. The duo publishes its discovery that shark skin actually generates thrust to give the fish an additional boost in The Journal of Experimental Biology at http://jeb.biologists.org/.
But first the scientists had to get hold of some fresh shark skin, so they went to a market in Boston where they found several large makos. Back in the lab, Oeffner carefully removed sections from a mako's skin and attached them to both sides of a rigid aluminium foil. Then he immersed the foil in a flow tank, reproduced the swimming motion of a fish by wiggling it from side to side and measured the rigid 'swimming' foil's speed by matching it with the flow of water moving in the opposite direction.
Having measured the foil's swimming speeds with intact skin – compete with denticles – Oeffner carefully sanded off the denticles and set the foil swimming again. However, instead of slowing down – as the duo had expected – the denticle-free foil speeded up. So the shark skin's denticle surface impeded the rigid swimmer. 'But then we remembered our premise that the sharks aren't rigid', remembers Lauder, so how would the shark skin perform when flexing like a real fish?
Gluing two pieces of shark skin together to produce a flexible foil, Oeffner repeated the swimming experiment, and this time the denticles had a dramatic effect. The intact skin foil swam 12.3% faster than the sanded skin. The shark's rough surface improved the swimming performance spectacularly.
However, when the duo tested the swimming performance of two shark skin mimics – a sharp-edged riblet design and the famous Speedo® Fastskin® FS II fabric – they were in for a shock. Although the riblet surface improved the flexible foil's swimming speed by 7.2%, the dented surface of the Speedo® fabric had no effect at all. However, Lauder points out that figure-hugging Fastskin® swimming costumes probably enhance the swimmer's performance in other ways.
After proving that the denticles on shark skin significantly improve the fish's propulsion, Lauder and Oeffner were keen to find out how they affect fluid flows around the body. Returning the flexible shark skin foil to the swim tunnel, Oeffner and Lauder captured the water's swirling motion with laser light and realised that in addition to reducing drag, the skin was actively generating thrust.
'That's the number one surprise. It's not just the drag-reducing properties, but the denticles alter the structure of flow near the shark skin in a way that enhances thrust', explains Lauder. He is now keen to design physical models to see how altered denticle arrangements affect fluid flows over the skin and to build a computational model to tease apart the beneficial effects of the skin's thrust and drag reduction.
IF REPORTING ON THIS STORY, PLEASE MENTION THE JOURNAL OF EXPERIMENTAL BIOLOGY AS THE SOURCE AND, IF REPORTING ONLINE, PLEASE CARRY A LINK TO: http://www.jeb.biologists.org
REFERENCE: Oeffner, J. and Lauder, G. V. (2012). The hydrodynamic function of shark skin and two biomimetic applications. J. Exp. Biol. 215, 785-795.
This article is posted on this site to give advance access to other authorised media who may wish to report on this story. Full attribution is required, and if reporting online a link to http://www.jeb.biologists.org is also required. The story posted here is COPYRIGHTED. Therefore advance permission is required before any and every reproduction of each article in full. PLEASE CONTACT firstname.lastname@example.org
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Scientists at Helmholtz Zentrum München have succeeded in stimulating the regeneration of injured neurons in living fish by the use of light. To this end, they employed so-called Optogenetics, i.e. light inducible protein activation. The results have recently been published in the journal ‘Current Biology’.
The nervous system is built to last a lifetime, but diverse diseases or environmental insults can overpower the capacity of neurons to maintain function or to repair after trauma.
A team led by Dr. Hernán López-Schier, head of the Research Unit Sensory Biology and Organogenesis at Helmholtz Zentrum München, now succeeded in promoting the repair of an injured neural circuit in zebrafish.
Key for the researchers’ success was the messenger molecule cAMP, which is produced by an enzyme called adenylyl cyclase. For their experiment, the scientist used a special form of this enzyme which is inducible by blue light. Therefore, the scientists are able to specifically modulate the production of cAMP in cells expressing this enzyme by the use of blue light.*
The researchers used this system in zebrafish larvae** which had interrupted sensory lateralis nerves***. “However, when blue light was shone on severed nerves that expressed a photoactivatable adenylyl cyclase, their repair was dramatically increased,” remembers PhD student Yan Xiao who is the first author of the study.
“While untreated nerve terminals only made synapses again in five percent of the cases, about 30% did after photostimulation.” In simple terms: the scientists were able to stimulate the repair of a neuronal circuit by elevating cAMP with blue light.
“Optogenetics have revolutionized neurobiology, since the method has already been used to modify for instance the electrical activity of neurons. However, our results show for the first time how the repair of a complex neural circuit in a whole animal can be promoted remotely by the use of light”, explains López-Schier.
But the head of the study thinks that this is only the beginning: “Our results are a first step. Now we would like to investigate, whether these results can be extrapolated beyond single neurons in zebrafish, to more complex neuronal circuits of higher animals.” The scientist could think of using this method for future therapeutic approaches for the treatment of neuropathies like those occurring in the wake of Diabetes and other diseases.
* Optogenetics: As the name indicates, this cutting-edge technology combines elements of Optics and Genetics. Scientists make use of proteins which are sensitive to certain wavelengths of light. These are brought into the target cells with certain genetic methods. The so treated cells then change their respective phenotype depending on the exposure to light.
** Larvae of zebrafish are particularly well suited for optogenetic approaches, since their skin in transparent/translucent. Thus, the light can reach the respective target cells easily.
*** These nerves normally communicate external sensory signals to the brain, but cannot normally repair after injury.
Xiao, Y. et al. (2015). Optogenetic stimulation of neuronal repair, Current Biology, DOI: 10.1016/j.cub.2015.09.038
Link to the publication
As German Research Center for Environmental Health, Helmholtz Zentrum München pursues the goal of developing personalized medical approaches for the prevention and therapy of major common diseases such as diabetes mellitus and lung diseases. To achieve this, it investigates the interaction of genetics, environmental factors and lifestyle. The Helmholtz Zentrum München has about 2,300 staff members and is headquartered in Neuherberg in the north of Munich. Helmholtz Zentrum München is a member of the Helmholtz Association, a community of 18 scientific-technical and medical-biological research centers with a total of about 37,000 staff members.http://www.helmholtz-muenchen.de/en/index.html
The independent Sensory Biology and Organogenesis (SBO) research unit works with a zebra fish model system to examine cellular, molecular and physiological reactions to mechanical stimuli and sensory disorders. The focus areas are physical and mechanical tissue properties. The objectives are to examine the mechanisms that control sensory system development, self-regulation and regeneration and to research the evolution of the sensory organs that perceive the environment. http://www.helmholtz-muenchen.de/en/sbo/index.html
Contact for the media:
Department of Communication, Helmholtz Zentrum München – German Research Center for Environmental Health (GmbH), Ingolstädter Landstr. 1, 85764 Neuherberg - Phone: +49 89 3187 2238 - Fax: +49 89 3187 3324 – E-mail: email@example.com
Scientific contact at Helmholtz Zentrum München:
Dr. Hernán López-Schier, Helmholtz Zentrum München - German Research Center for Environmental Health (GmbH), Research Unit Sensory Biology and Organogenesis, Ingolstädter Landstr. 1, 85764 Neuherberg – Phone: +49 89 3187 2187 – E-mail: firstname.lastname@example.org
Kommunikation | Helmholtz Zentrum München - Deutsches Forschungszentrum für Gesundheit und Umwelt
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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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Amateur astronomy has undergone a revolution in the last few years, thanks to the advent of affordable sophisticated technology. A modern amateur’s computer-controlled telescope can find and then track any celestial body. The CCD astrocamera plugged into it can obtain images that years ago would have required a large professional telescope. The amateur’s computer can perform image processing, and even astrometry and photometry. Tasks that were the sole province of the professional astronomers of not that many years ago can now be undertaken by amateurs. As you might expect, the main bulk of this book reflects this new astronomy.
KeywordsReal Field Comparison Star Cometary Coma Celestial Equator Bright Comet
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Freshwater ecosystems in northern regions are home to significantly more species of water fleas than traditionally thought, adding to evidence that regions with vanishing waters contain unique animal life.
The new information on water fleas -- which are actually tiny crustaceans -- comes from a multi-year, international study that was published Feb. 24 in the journal Zootaxa.
The researchers scoured the globe seeking the creatures and found them inhabiting northern lakes and ponds in locations from Alaska to Russia to Scandinavia.
After analyzing the anatomy and genetic makeup of many different specimens, the team conclusively determined that at least 10 species of the crustaceans existed -- five times as many as thought for much of the last century.More than half the diversity was found in northern latitudes, where rapid freshwater habitat loss is occurring due to melting permafrost, increased evaporation and other changes tied to climate change.
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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.
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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.
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Google presents a new technology at the climate change conference in Copenhagen that helps scientists track global deforestation.
At the International Climate Change Conference in Copenhagen, search giant Google demonstrated a technology prototype that enables online, global-scale observation and measurement of changes in the earth's forests. The technology will be provided to the world as a not-for-profit service, the company stated.
The prototype is currently available to a small set of partners for testing purposes: Google noted that while it's not yet available to the general public, the company expects to make it more broadly available over the next year.
The technology uses the help of satellite imagery to track deforestation over a period of time and measure the level of loss. While it is possible to view levels of deforestation at different times, Google.org’s engineering managers, Rebecca Moore and Dr. Amy Luers, said there hasn’t been a way to calculate how quickly the world’s forests are disappearing. “With this technology, it's now possible for scientists to analyze raw satellite imagery data and extract meaningful information about the world's forests, such as locations and measurements of deforestation or even regeneration of a forest,” they wrote on the company’s blog.
The United Nations has already proposed a framework known as REDD that would provide financial incentives to rainforest nations to protect their forests; Google argues implementing a global REDD system will require that each nation have the ability to accurately monitor and report the state of their forests over time, in a manner that is independently verifiable. “However, many of these tropical nations of the world lack the technological resources to do this, so we're working with scientists, governments and non-profits to change this,” Moore and Luers wrote.
eWeek has contributed to the report.
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Authors: Eric Su
A standing wave consists of two identical waves moving in opposite direction. A frequency detector moving toward the standing wave will detect two different frequencies. One is blueshifted, the other is redshifted. The distance between two adjacent nodes in the standing wave is equal to half of the wavelength of both waves. Consequently, the wave detector will detect different speeds from both waves due to the same wavelength and the different frequencies. The calculation of speed is demonstrated with a typical household microwave oven which emits microwave of frequency range around 2.45 GHz and wavelength range around 12.2 cm.
Comments: 2 Pages. microwave speed relativity reference frame
[v1] 2017-05-21 16:06:50
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Paris, 24 Sep 2002
Tales of asteroids or comets in a collision course with the Earth are always good to fill space in newspapers during the quiet summer months. Is there any truth in these tales of impending doom and if so, what is ESA doing about it?
Certainly if a large comet or asteroid were to collide with the Earth the result could be apocalyptic. But, the possibilities of this happening are remote. The latest asteroid scare story to hit the press was that of 2002NT7, believed to be about 2 km in diameter. First reports said that 2002NT7 could collide with the Earth on 1 February 2019 at a speed of 28 km/s. The result would be widespread devastation, if not the end of the world, predicted in some papers. .
Fortunately for those of us who will be around in 2019 the possibility of this happening is now reported to be negligible. Although first estimates gave odds of about 1 in 100,000, now that scientists have had more time to study this 'new' asteroid and its orbit - only discovered in July - the odds have lengthened considerably.
Asteroids and comets whose orbits bring them close to the Earth are referred to as Near Earth Objects (NEOs). Those less than 50 m in size burn up on entry into the Earth's atmosphere. It is estimated that around 50 000 fragments of NEOs fall to Earth as meteorites each year, most far too small to do any damage.
Fortunately, the larger the NEO the less likely it is to collide with the Earth, as even a NEO 300 m in diameter could wipe out an entire country if it hit land, and cause even more damage if it struck an ocean, as it would trigger the enormous waves known as tsunamis that could devastate many coastal cities.
According to astronomers, a NEO of around 50 m in diameter collides with the Earth every 100 to 300 years and a NEO with a diameter of 1 km occurs every few hundred thousand years. Very large collisions, that could threaten the existence of all large land species, occur once every hundred million years. To date, astronomers have identified 600 NEOs bigger than 1 km but believe that there are possibly half as many again still waiting to be tracked.
But, even if the odds are on our side, the fact remains that at some time or other the Earth will again be hit by a large NEO, such as that thought to have wiped out the dinosaur population 65 million years ago. So to return to the second question, what is ESA doing about it?
ESA and NEOs
ESA has been supporting activities to monitor and investigate NEOs for a number of years. In ESA's view, these are activities that surpass national boundaries and which it considers to be a service to the international community. ESA's space research institute outside Rome in Italy, ESRIN, also hosts the Spaceguard Central Node. This private non-profit scientific organisation aims to support and coordinate NEO research throughout the world.
Now ESA has launched a new project to seek the best ideas from industry and academia on how to protect the Earth from NEOs and in particular, to learn more about them. The damage an NEO causes depends on the speed at which it hits the Earth, its size and what it is made of. So, the more we know about them the easier it will be to decide which are potentially dangerous and what is the best action to take.
In June a panel of NEO experts met to select the best six proposals. Andrés Gálvez, one of ESA's representatives on the panel reports, "the six winning proposals were selected because the mission concepts would help to answer essential questions on the NEO threat such as: how many are there, what is their size and mass, are they compact bodies or loose rock aggregates?
This information, as well as other data, is needed before adequate mitigation procedures can be developed."
The winning six are:
· Don Quijote: This proposal is for a spacecraft 'named Hidalgo' to hit a target asteroid at high speed while the other, 'Sancho', observes what happens from a safe distance before, during and after the impact, to gather information on the NEO's internal structure. This will also test possible future mitigation techniques, such as whether 'Hidalgo' could be programmed to hit the asteroid to change its orbit so that it avoids collision with the Earth.
· Earthguard 1: A spacecraft using propulsion technology such as solar sails or electric propulsion, or 'hitching a ride' on a future launch, would be placed in a heliocentric orbit to observe NEOs from a more favourable viewpoint.
· ISHTAR: This would probe the interior of an NEO to study its structure and assess the danger with radar tomography, a new technology that uses ground penetrating radar to make images of the interior of a solid body.
· SIMONE: A fleet of low-cost small satellites would fly by and/or rendezvous with a number of NEOs to characterise the population and obtain first hand information on the hazardous objects.
· EUNEOS: A space survey would be undertaken from an inner solar system orbit to find the most dangerous NEOs. These are often the most difficult to observe from ground-based observatories as very often these faint objects only appear in the daytime sky or very close to the horizon.
· Remote observation of NEOs from Space: A space-based observatory to carry out remote sensing and detect physical characteristics of NEOs, such as size, composition and surface properties.
Andrea Carusi, President of the Spaceguard Foundation, believes "it is very important that ESA, one of the largest space agencies, and one that is already deeply involved in support of NEO studies, has decided to take a further step in this direction".
Preliminary studies, funded by the Agency's General Studies Programme, are now under way for the six proposals. Once these are submitted in 2003, ESA will judge whether one or more of the proposed missions is feasible and merits further development.
For further information, please contact :
ESA Media Relations Service
Tel : +33(0)126.96.36.19955
Press Release N° 60-2002
European Space Agency
Press Release N° 60-2002 | <urn:uuid:bef899a9-f224-4686-b81f-a239608898c0> | 3.703125 | 1,287 | News (Org.) | Science & Tech. | 44.326785 | 95,645,738 |