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Engineering Protein Stability with Atomic Precision
CREDIT Emily G. Baker et al.
This research will help to design small proteins and small molecules that could be the basis for future biotechnologies and medicines.
A team of chemists and biochemists from the Bristol BioDesign Institute have designed a new protein structure.
This is much simpler than most naturally occurring proteins, which has allowed the scientists to unpick some of the molecular forces that assemble and stabilise protein structures. The work is published in the journal Nature Chemical Biology.
Proteins are the workhorses of biology. For example, they help convert light energy into sugar in plants, transport oxygen from our lungs to our muscles, and combine sugar and oxygen to release energy to make the muscles work. To perform these tasks, proteins must adopt specific 3D structures, called protein folds.
In chemical terms, proteins are polymers, or strings of amino acids, much like the beads of a necklace. There are 20 different chemistries of the amino-acid building blocks.
It is the combination of these along the protein string that determines how a protein folds up into its functional 3D shape. Despite decades of effort, scientists still don’t understand how biology achieves this protein-folding process, or, once folded, how protein structures are stabilised.
To address this problem, the Bristol team have combined two types of protein structure—called an a helix and a polyproline II helix—to make a stripped down, or simplified protein called a miniprotein.
This is basic science with the simple aim of seeing how small a stable protein structure can be. It is important, as natural proteins are usually very large and cumbersome structures, which are currently too complicated for chemists and biochemists to dissect and understand.
In the miniprotein, which the team call 'PPa', the two helices wrap around each other and their amino acids contact intimately in what are termed ‘knobs-into-holes’ interactions. This was expected, indeed the team designed PPa from scratch based on their understanding of these interactions.
Dr Emily Baker, who led the research in Professor Dek Woolfson’s laboratory, decided to change some of the amino acids in these knobs-into-holes interactions to non-natural amino acids, which the wonders of modern protein chemistry allow.
By doing this, Emily discovered that as well as the expected forces that hold proteins together, known as hydrophobic interactions, other more-subtle forces were at play in stabilising the miniprotein structure.
Chemists know these small forces as CH–p interactions, and they are found throughout the chemical world. When Drs Gail Bartlett and Kieran Hudson, also from the Bristol team, searched the thousands of natural protein structures available they found many examples of these CH–p interactions.
Moreover, the proteins that they occur in play roles in different biological process, many of which are associated with disease. This presents potential targets for new drugs, and the CH–p interactions may provide a valuable new route into developing these.
Dr Baker explained: "Our work has implications not only for understanding the basic science of protein folding and stability, but also for guiding the design and engineering of new proteins and drug molecules."
Professor Woolfson added: "This is precisely what the new Bristol BioDesign Institute is about. We aim to deliver the very best basic science. In this way, we will open unforeseen routes to translating fundamental science into biotechnology and biomedical applications."
This article has been republished from materials provided by The University of Bristol. Note: material may have been edited for length and content. For further information, please contact the cited source.
Woolfson et al 'Engineering protein stability with atomic precision in a monomeric miniprotein' Nature Chemical Biology (2017), DOI: 10.1038/nchembio.2380.
‘Good Cholesterol’ May Not Always be Good for Postmenopausal WomenNews
Postmenopausal factors may have an impact on the heart-protective qualities of high-density lipoproteins (HDL) – also known as ‘good cholesterol’ – according to a study led by researchers in the University of Pittsburgh Graduate School of Public Health.READ MORE
What Makes Good Brain Proteins Turn Bad?News
The protein FUS is implicated in two neurodegenerative diseases: amyotrophic lateral sclerosis (ALS) and frontotemporal lobar degeneration (FTLD). Using a newly developed fruit fly model, researchers have zoomed in on the protein structure of FUS to gain more insight into how it causes neuronal toxicity and disease.
5th edition of the International Conference Clinical Oncology and Molecular Diagnostics
Jun 17 - Jun 18, 2019 | <urn:uuid:11f62f33-ee7b-4d12-a9cf-0e3e8b5bc097> | 3.546875 | 993 | News Article | Science & Tech. | 31.794193 | 95,598,657 |
Program a robot to explore a world
You construct a program for a robot, then watch him explore a world. The world has people who can hurt you, objects you can bump into, and food you can eat. The goal of the game is to collect as many prizes as possible before you are killed run out of energy. The robot program is written in a text file, which doesn't limit programmers to a visual interface. However, such an interface (which will generate Scheme code) is also available for use by non-programmers.
released on 3 August 2008
git clone git://git.sv.gnu.org/gnurobots.git
|License||Verified by||Verified on||Notes|
|License:GPLv3orlater||Bendikker||10 May 2018|
Leaders and contributors
|Joshua Judson Rosen||Maintainer|
|Iain R. Learmonth||contributor|
Resources and communication
|Ruby (Ref) (R)||https://rubygems.org/gems/robots|
|VCS Repository Webview||https://git.savannah.gnu.org/cgit/gnurobots.git|
|Required to build||guile-2.0|
|Required to build||gtk+2.0|
This entry (in part or in whole) was last reviewed on 10 May 2018.
Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1.3 or any later version published by the Free Software Foundation; with no Invariant Sections, no Front-Cover Texts, and no Back-Cover Texts. A copy of the license is included in the page “GNU Free Documentation License”.
The copyright and license notices on this page only apply to the text on this page. Any software or copyright-licenses or other similar notices described in this text has its own copyright notice and license, which can usually be found in the distribution or license text itself. | <urn:uuid:777f65b0-9d7a-46e5-81ab-5676037333e3> | 2.546875 | 433 | Truncated | Software Dev. | 57.984199 | 95,598,693 |
Was the early universe a LIQUID? Atom smasher creates smallest ever droplets... and gives clues about the primordial soup created by the Big Bang
- Scientists smashed protons and lead atoms together at CERN near Geneva
- They hoped to replicate the quark-gluon plasma from the early universe
- Particles formed tiny droplets 100,000 times smaller than a hydrogen atom
- These plasma droplets behaved like a 'perfect liquid', which suggests this may have been how the universe looked in the moments after the Big Bang
It might seem more of a philosophical question, but scientists working at the world's biggest atom smasher have raised the question of how small a droplet of liquid can get before it becomes a gas.
The researchers at the Large Hadron Collider at CERN near Geneva, have created what they claim are the world's smallest droplets while conducting experiments to study what the early universe would have looked like.
Scientists had been attempting to produce the primordial soup of subatomic particles that existed shortly after the Big Bang known as the quark-gluon plasma.
Scroll down for video
Scientists colliding atoms of lead with protons (illustrated) in the Large Hadron Collider at CERN, near Geneva, produced tiny droplets of plasma which were thought to exist in the moments after the Big Bang
By colliding lead atoms and protons together they were able to produce temperatures 250,000 times hotter than the core of the sun to create this plasma.
However, when they examined the resulting material, they were surprised to see that it behaved more like a liquid than a gas in droplets composed of just 100 to 200 subatomic particles.
Quarks and gluons are elemental particles that make up all other subatomic particles and the atoms they form.
In the seconds after the Big Bang, the normally powerful forces that bind these subatomic particles together were weakened.
This resulted in a substance known as the quark-gluon plasma - a strange soup of superheated material.
But rather than behaving like a superheated gas as scientists might expect, it appears this primordial soup of particles was more of a liquid, according to research from the Large Hadron Collider.
The tiny fireballs created inside the 17 mile long particle accelerator, which is buried 300ft beneath the Alpine foothills along the Swiss-French border, have enabled scientists to recreate some of the conditions that existed shortly after the Big Bang.
These plasma droplets were found to be more than 100,000 times smaller than a hydrogen atom.
The findings also suggest that the early universe may have been more like a liquid than a ball of super-heated gas as many astrophysicists believe.
Dr Shenguang Tuo, who was leading the research, said: 'Everyone was surprised when we began finding evidence for liquid behaviour. It caused some very intense debates.'
One of the key properties of a liquid is the ability to flow by exerting an attractive force on its neighbours that is not quite strong enough to lock them together like a solid.
Dr Tuo and his colleagues searched the data from lead-proton collisions in the LHC for correlations between groups of four, six and eight of the particles thrown out by the collisions.
Dr Tuo said: 'These measurements confirmed that we were seeing this coherent behaviour even in droplets producing as few as 100 to 200 particles.
The results have been replicated by researchers at the Relativistic Heavy Ion Collider at the Brookhaven National Laboratory by colliding gold and helium ions together.
The 17 mile long Large Hadron Collider has allowed scientists to recreate some of the conditions that emerged in the moments after the Big Bang by smashing the nuclei of atoms together at high speeds
They found hot sports emerged on the gold ions that then merged into a quark-gluon plasma droplet.
BEHOLD THE PENTAQUARK
Earlier this year scientists at the Large Hadron Collider announced they had discovered a new particle called the pentaquark.
This previously unseen class of particle was first predicted to exist in the 1960s but has eluded physicists until now.
It was detected by Cern's Large Hadron Collider beauty (LHCb) experiment at the LHC in Switzerland.
The LHCb experiment specialises in investigating the slight differences between matter and antimatter.
LHCb spokesman Guy Wilkinson said: 'The pentaquark is not just any new particle.
'It represents a way to aggregate quarks, namely the fundamental constituents of ordinary protons and neutrons, in a pattern that has never been observed before in over fifty years of experimental searches.
'Studying its properties may allow us to understand better how ordinary matter, the protons and neutrons from which we're all made, is constituted.'
The findings, which were published in the journal Physical Review Letters, have helped to show that not only does this plasma behave like a liquid, it appears to be a nearly perfect liquid.
This means it has zero viscosity and flows without any resistance. If you were swirl it in a glass then the liquid would continue to swirl almost indefinitely.
The findings were being discussed at the conference Quark Matter 2015 taking place this week in Kobe Japan.
They build on some of the first discoveries to be made with the LHC since it was switched on in 2010.
Scientists working on the ATLAS detector obtained results that suggested the super-heated plasma - which was more than 10 trillion degrees Celsius - created after the Big Bang, appeared to behave like a very dense liquid.
The latest findings suggest this plasma liquid would have been unlike anything we are used to.
Professor Julia Velkovska, a particle physicist at Vanderbilt University who was part of the Large Hadron Collider's CMS detector team that conducted the research, said: 'Although the LHC collisions release 25 times more energy than the RHIC collisions, we don't see much difference in the droplet-formation process.
'Once you have reached the threshold, adding more energy doesn't seem to have much effect. I guess you can't get more perfect than perfect.'
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2 H 2 + O 2 → 2 H 2 O. +. Identify the factors that could affect the rate of a chemical reaction. Use the Collision Theory to explain the factors influencing the rate of a reaction. Explain the effect these factors have on the shape of a kinetic energy distribution curve.
Identify the factors that could affect the rate of a chemical reaction.
Rate of reaction increases with increased surface area(crushing, grinding) .
More particles involved, more frequent collisions.
Rate of reaction increases with increased concentration (mol/L) of particles.
Moreparticles with activation energy -
more chances of a successful collision.
Only affects reaction rates of gaseous reactions.
Rate of reaction increases with decreased volume of the container - mimics higher [ ].
Closer particles – more chance of collisions.
Rate of reaction increases with increased temperature.
MoreKEperparticles – more frequentcollisions and moreEA.
1. Comparing reactions with similar compounds:
Less bonds to break, faster the reaction.
2 NO(g) + O2(g) → 2 NO2(g)
2 C8H18(g) + 25 O2(g) → 16 CO2(g) + 18 H2O(g)
Covalent bonds takes longer to break than aqueous.
(aq) are already separated into ions, so are instantaneous.
H2(g) + I2(g) → 2 HI(g)
KNO3(aq) + NaI(aq) → KI(aq) + 2 NaNO3(aq)
(g) faster> (l) > (s)
A catalyst speeds up or starts a reaction by lowering the activation energy.
Enzymes are known as biological catalysts.
An inhibitor is the opposite of a catalyst.
To decrease reaction rate - do the opposite.... | <urn:uuid:8f3d1c3e-c447-46c0-8700-3e44baac46c3> | 4.0625 | 396 | Content Listing | Science & Tech. | 55.760769 | 95,598,738 |
tokamak(redirected from Torus (nuclear physics))
Also found in: Thesaurus, Encyclopedia.
A doughnut-shaped chamber used in fusion research in which a plasma is heated and confined by magnetic fields.
[Russian, from to(roidal'naya) kam(era s) ak(sial'nym magnitnym polem), toroidal chamber with axial magnetic field.]
(General Physics) physics a toroidal reactor used in thermonuclear experiments, in which a strong helical magnetic field keeps the plasma from contacting the external walls. The magnetic field is produced partly by current-carrying coils and partly by a large inductively driven current through the plasma
[C20: from Russian to(roidál'naya) kám(era s) ak(siál'nym magnitnym pólem), toroidal chamber with magnetic field]
to•ka•mak(ˈtoʊ kəˌmæk, ˈtɒk ə-)
a type of experimental nuclear fusion reactor in which a plasma of ions circulates in a toroidal tube and is confined to a narrow beam by an electromagnetic field.
[1960–65; < Russian tokamák, for to(roidál'naya) kám(era s) ak(siál'nym magnítnym pólem) toroidal chamber with an axial magnetic field]
Switch to new thesaurus
|Noun||1.||tokamak - a doughnut-shaped chamber used in fusion research; a plasma is heated and confined in a magnetic bottle|
chamber - a natural or artificial enclosed space
magnetic bottle - container consisting of any configuration of magnetic fields used to contain a plasma during controlled thermonuclear reactions | <urn:uuid:12060fff-c0fa-4c2e-bf8d-aae301803a59> | 3.3125 | 393 | Structured Data | Science & Tech. | 24.668452 | 95,598,740 |
Conservation is not always equal. If you go to a zoo you’ll find inescapable evidence of that, the megafauna are the main attractions; elephants, tigers and of course great apes are what you go to see. Visitor numbers are not determined by the species of rare invertebrates, birds or even the monkeys you’ll find housed in many collections and this same pattern is repeated across much of conservation science. A new study in the journal Frontiers in Ecology and the Environment has highlighted the problematic bias caused by primarily studying great apes across Asia and Africa.
The study highlights that this bias has implications for a huge range of other species as scientists focus on protected areas which home the charismatic great apes. As a result of this we now next to nothing about protected areas where the great apes are missing.
Whilst the bias surrounding species selection for studies has long been known, anthropologist Andrew J. Marshall of University of Michigan and his colleagues decided to use Google scholar to determine whether this bias influences where people work.
By searching for publications which contained the names of one or more of the 565 protected areas across Africa and Asia where great apes are known to occur. They then used the number of hits found on Google Scholar as a proxy for the research effort in each protected area.
What they found was worrying, out of the 52,502 publications their search found more than 50% of those papers were focussed on 17 protected areas. Even worse than the clear bias shown for studying certain areas is the evident lack of study in others. One-third of African and one-fifth of Asian did not return a single hit on Google scholar.
“We imagined that research allocation might be skewed, but did not envisage such a strong bias.” claims Marshall. Of course his study could not determine a reason for this bias however he suspects it’s probably a similar reason as to why great apes are popular zoo attractions. People are drawn to charismatic species and those which express similar anthropogenic features to us. There is also the factor that great apes are more broadly known and have better research facilities.
With regards to a bias towards larger national parks, this could again be attributed towards a number of factors. For a start they are more likely to provide pristine environments which are favourable to scientists. Moreover the larger parks are better protected and provide safer, more stable environments for researchers and funders.
These obvious benefits are however outweighed by the negative impact this bias can have upon protected areas. As scientists are not studying the species, any local threats and conservation opportunities in a vast area therefore there is a vast lack of knowledge. Marshall highlights this problem; “If our knowledge of threatened species and ecosystems is based primarily on data collected in the places where populations are well protected and ecosystems are functioning best, we likely have a dangerously optimistic view of the world.”
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Expertise derived from working on the joint NASA-ESA Cassini-Huygens mission to Saturn and its moon Titan is now being applied to underground drilling machines. This is providing tunnelling engineers with an improved ability to virtually "see" some 40 metres into solid rock and pinpoint obstacles ahead.
Trude - the worlds biggest tunnel drilling machine
Tunnel drilling on Earth gains from Saturn/Titan mission
It´s an old miners´ expression: "There is darkness in front of the pick". Billions of years of geological history has laid down complex folds of strata, patterns of faulting and embedded irregular objects in the ground beneath our feet. The character of the earth can and often does change unexpectedly with every metre excavated.
But with modern high-speed tunnelling, sudden geological shifts may damage the cutting head of drilling machines and lead to expensive delays in multi-million Euro excavation projects.
German tunnelling company Herrenknecht AG - famous for drilling the Elbe tunnel in Hamburg using the world´s single largest tunnelling machine - has developed a new method of charting what lies ahead beyond the tunnel face.
Scientists discover Earth's youngest banded iron formation in western China
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Drones survey African wildlife
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For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
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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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"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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What factors will affect the time of a falling paper cone
Disclaimer: This essay has been submitted by a student. This is not an example of the work written by our professional essay writers. You can view samples of our professional work here.
Any opinions, findings, conclusions or recommendations expressed in this material are those of the authors and do not necessarily reflect the views of UK Essays.
The issue raised is the motion of paper made cones within air as they are released. The time that the cone will take to reach ground level from the moment of its release depends on several variables, which have to be investigated in order to conclude whether changing them would be relevant in affecting the period of time needed.
There are several factors which theoretically could affect the time, assuming that the air is homogenous throughout the room and by using the same paper. We have to understand that a higher or a lower top speed will be the factor which changes the time needed. Thus the factors affecting top speed will have to be investigated. These are shape, top angle, height, type of paper and resistive forces. Some can be cancelled out before experimentation as we know from theory that a mass difference will not affect the free falling object (it will actually but to a negligible extent).
To investigate how different factors change the time needed one would have to set up a laboratory experiment. Immediately one encounters the first issue: how far will the paper cone will have to be put in order to reach its terminal velocity? As paper cones are quite light in terms of mass one can assume that a 3 meter chute is all right, as according to Newtonian physics the drag (air resistance), i.e. the upwards force will soon be equal to the weight of the paper. The aforementioned variables (top angle, resistive forces...) will have to be tested by using different values. To achieve this, the experimenter will have to probe those relationships.
Size: cones of different sizes but same paper will have different masses but this will not affect the time as weight is not a criterion after terminal velocity has been reached.
Drag coefficient: the drag coefficient is a dimensionless quantity which determines the aerodynamic properties of an object. The smaller it is, the lower the resistive values of fluid air. For instance for a normal cone it is of 0.5 whilst a cube has a drag coefficient (Cd) of about 1.05. The formula to find this value is Cd= Fd / 0.5VÏ. The airs density is an uncontrollable constant whereas the mass shall be manipulated in order to see the effect. The experimenter will create three cones of different mass, let them drop off from a same height and observe. The time shall be measured.
Only simple tools such as a scale, a stopwatch or rulers shall be used, no complicated machines such as lasers or position sensors.
Uncontrollable constants: air's fluidity
Controllable variables: mass, shape, aerodynamics
Uncontrollable variables: time
Diagram of set up
Cone a is the sample cone
Cone b is the same shape and material as A but is an scaled up version. This is done so that the effects of mass difference can be investigated.
Cone c is the same size as A but is made of a different kind of paper, a rougher one. This is done so that the effects of the cone's aerodynamics can be investigated.
Cone d is of different shape than the B but has the same surface area (thus the same mass). This is done to investigate how much the steepness of the sides will affect the cone.
The cone is dropped from 3 meters and simultaneously the stopwatch sets off. As it hits the earth the chronometer will have to be stopped. The figures are recorded. The process is repeated at least 5 times with all cones and thus an average is drawn. Thereafter the results are compared. The smaller the time needed, the more aerodynamic the shape is. | <urn:uuid:2fa17ec5-6905-4a75-85a4-4c50b06a498b> | 3.109375 | 821 | Truncated | Science & Tech. | 51.207802 | 95,598,815 |
Some people believe that the Earth is being harmed （damaged） by human activity. Others feel that human activity makes the Earth a better place to live. What is your opinion? Use specific reasons and examples to support your answer.
While the past few centuries have witnessed increasingly better quality of human life, human activity is doing more and more harm to the Earth. Natural resources are being depleted and pollution is being created as a result of development of technology. Natural areas are being damaged as a result of urban expansion to populate more people.
First, we harm the Earth by using more and more natural resources. If we fell too many trees at one time to build
houses and make paper, or if we cut down trees before they grow to maturity, they can hardly grow back in time. As worrisome as overcutting of trees is overfishing. With improved technology and greater drive for money, fish of all kinds are being over hunted, reducing the biomass of some fish to the verge of extinction. Whaling seems a most irksome issue. While most countries argue against it, some countries go whaling to extremes. We often take it for granted that we have unlimited natural resources and use them in a wasteful manner, bringing about great losses.
Second, we damage the Earth by producing pollution in all forms. Factories pollute water and the air. Vehicles pollute the air. Nuclear-related and electronic products are playing an increasingly big role in polluting the air, especially when we dispose of related waste carelessly. We take it for granted that Nature can help clean everything, but it can not.
Third, expanding towns and cities are taking up more and more land. As populations flood to cities, new houses and stores have to be built to accommoda | <urn:uuid:51056696-d241-4ab2-aefa-0dded9f112ab> | 2.890625 | 361 | Q&A Forum | Science & Tech. | 43.878699 | 95,598,817 |
Never before have astrophysicists measured light of such high energy from a celestial object so far away. Around 7 billion years ago, a huge explosion occurred at the black hole in the center of a galaxy. This was followed by a burst of high-intensity gamma rays. A number of telescopes, MAGIC included, have succeeded in capturing this light. An added bonus: it was thus possible to reconfirm Einstein's General Theory of Relativity, as the light rays encountered a less distant galaxy en route to Earth - and were deflected by this so-called gravitational lens.
The object QSO B0218+357 is a blazar, a specific type of black hole. Researchers now assume that there is a supermassive black hole at the center of every galaxy. Black holes, into which matter is currently plunging are called active black holes. They emit extremely bright jets. If these bursts point towards Earth, the term blazar is used.
Full moon prevents the first MAGIC observation
The event now described in "Astronomy & Astrophysics" took place 7 billion years ago, when the universe was not even half its present age. "The blazar was discovered initially on 14 July 2014 by the Large Area Telescope (LAT) of the Fermi satellite," explains Razmik Mirzoyan, scientist at the Max Planck Institute for Physics and spokesperson for the MAGIC collaboration. "The gamma ray telescopes on Earth immediately fixed their sights on the blazer in order to learn more about this object."
One of these telescopes was MAGIC, on the Canary Island of La Palma, specialized in high-energy gamma rays. It can capture photons - light particles - whose energy is 100 billion times higher than the photons emitted by our Sun and a thousand times higher than those measured by Fermi-LAT. The MAGIC scientists were initially out of luck, however: A full moon meant the telescope was not able to operate during the time in question.
Gravitational lens deflects ultra-high-energy photons
Eleven days later, MAGIC got a second chance, as the gamma rays emitted by QSO B0218+357 did not take the direct route to Earth: One billion years after setting off on their journey, they reached the galaxy B0218+357G. This is where Einstein's General Theory of Relativity came into play.
This states that a large mass in the universe, a galaxy, for example, deflects light of an object behind it. In addition, the light is focused as if by a gigantic optical lens - to a distant observer, the object appears to be much brighter, but also distorted. The light beams also need different lengths of time to pass through the lens, depending on the angle of observation.
This gravitational lens was the reason that MAGIC was able, after all, to measure QSO B0218+357 - and thus the most distant object in the high-energy gamma ray spectrum. "We knew from observations undertaken by the Fermi space telescope and radio telescopes in 2012 that the photons that took the longer route would arrive 11 days later," says Julian Sitarek (University of ?ódz, Poland), who led this study. "This was the first time we were able to observe that high-energy photons were deflected by a gravitational lens."
Doubling the size of the gamma-ray universe
The fact that gamma rays of such high energy from a distant celestial body reach Earth's atmosphere is anything but obvious. "Many gamma rays are lost when they interact with photons which originate from galaxies or stars and have a lower energy," says Mirzoyan. "With the MAGIC observation, the part of the universe that we can observe via gamma rays has doubled."
The fact that the light arrived on Earth at the time calculated could rattle a few theories on the structure of the vacuum - further investigations, however, are required to confirm this. "The observation currently points to new possibilities for high-energy gamma ray observatories - and provides a pointer for the next generation of telescopes in the CTA project," says Mirzoyan, summing up the situation.
Dr. Razmik Mirzoyan
Max Planck Institute for Physics
Phone: +49 89 32354-328
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Nano-kirigami: 'Paper-cut' provides model for 3D intelligent nanofabrication
16.07.2018 | Chinese Academy of Sciences Headquarters
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
16.07.2018 | Physics and Astronomy
16.07.2018 | Life Sciences
16.07.2018 | Earth Sciences | <urn:uuid:cb10ac1b-20dd-4a52-9280-49e769cdcdf6> | 3.65625 | 1,535 | Content Listing | Science & Tech. | 43.024042 | 95,598,827 |
Liquids and Solutions and Solids
- 1 Structure and Intermolecular forces
- 2 3 types of intermolecular forces
- 3 3 types of Crystalline Solid States
Structure and Intermolecular forces[edit | edit source]
Interactive molecular forces[edit | edit source]
attractive or repulsive forces between molecules, caused by partial charges. The attractive forces are the ones that work to overcome the randomizing forces of kinetic energy. The structure and type of bonding of a particular substances have quie a bit to do with the types of interaction and the strength of that interaction.
3 types of intermolecular forces[edit | edit source]
Ion-dipole Intermoelcular Forces[edit | edit source]
attraction of an ion and one end of a polar molecule (dipole) This type of attraction is especially important in aqueous salt solutions where the ion attracts water molecules and may form a hydrated ion. this is one of the strongest of the intermolecular forces.
Dipole-Dipole Intermoelecular Forces[edit | edit source]
These forces result from the attraction of the positive end of one dipole to the negative end of another dipole. For example, in gaseous hydrogen chloride, HCl (g) , the hydrogen end has a partial positive charge and the chlorine end has a partial negative charge, due to chlorine's higher electronegativity.
Hydrogen Bond INtermolecular Forces[edit | edit source]
a special type of dipole-dipole attraction in which a hydrogen atom is polar-covalently bonded to one of the following extremely electronegative elements: N,O, or F. These hydrogen bonds are extremely polar bonds by nature, so there is a greater degree of charge separation whithin the molecule. Therefore, the attraction of the positively charged hydrogen of one molecule and the negatively charged N, O or F of another molecule is extremly strong. These hydrogen bonds are in general, stronger than the typical dipole-dipole interaction
Ion-induced Dipole and Ipole induced Dipole intermolecular Forces[edit | edit source]
Theses types of attraction occus when the charge on an ion or a dipole distorts the electrons cloud of a nonpolar molecule and induces a temporary dipole in the nonpolar molecule. LIke Ion-dipole intermolecular forces, these also requires two different species. They are fairly week interactions
London (Dispersion) Intermolecular Forces[edit | edit source]
The intermoelecular attraction occurs in all substances, but is significant only when the other types of intermolecular forces are absent.This is an extremeyly weak interaction, but it is strong enough to allow us to liquefy nonpolar gases such as hydrogen and nitrogen.
3 types of Crystalline Solid States[edit | edit source]
regular ordering of the particles in a three-dimensional structure called the crystal lattice. IN this crystal lattice there are repeating units called unit cells.
Simple Cubic Unit Cell[edit | edit source]
particles located at the corner of a simple cube
Body-centered Unit Cell[edit | edit source]
particles located at the corner of the cube and in the center of the cube
face-centered unit cell[edit | edit source]
particles at the corners and one in the center of each face of the cube, but not in the center of the cube itself. | <urn:uuid:a62396c7-4c43-4487-bff3-06825182afe3> | 3.46875 | 746 | Knowledge Article | Science & Tech. | 8.325181 | 95,598,834 |
How AI will revolutionize climate science: Experts say machine learning could dramatically improve predictions
- Major challenge in predicting climate models is accurately representing clouds
- New artificial intelligence can better represent clouds in coarse resolution
- Trained a deep neural network to learn from simulation that represents clouds
- Machine learning representation could predict many of the cloud heating, moistening, and radiative features that are essential to climate simulation
Researchers have long struggled with accurately predicting climate models because clouds and their atmospheric heating and moistening prove to be a challenge.
This can prevent accurate climate models from being made, but correct predictions of climate change in response to increased greenhouse gas concentrations are essential for policy-makers
However, researchers from Columbia Engineering have used machine learning techniques to better represent clouds in coarse resolution
Researchers have long struggled with accurately predicting climate models because clouds and their atmospheric heating and moistening prove to be a challenge
'This could be a real game-changer for climate prediction,' said Pierre Gentine, lead author of the paper, and a member of the Earth Institute and the Data Science Institute.
'We have large uncertainties in our prediction of the response of the Earth's climate to rising greenhouse gas concentrations.
'The primary reason is the representation of clouds and how they respond to a change in those gases,' he said.
'Our study shows that machine-learning techniques help us better represent clouds and thus better predict global and regional climate''s response to rising greenhouse gas concentrations.'
The researchers used an idealized setup called an aquaplanet (a planet with continents) to train a deep neural network to learn from a simulation that explicitly represents clouds.
New artificial intelligence can better represent clouds in coarse resolution. The researchers used an idealized setup called an aquaplanet (a planet with continents) to train a deep neural network
WHY ARE CLIMATE MODELS DIFFICULT TO PREDICT?
The main problem with climate models is uncertainty.
In particular, something called the 'equilibrium climate sensitivity' measure has been causing scientists a headache.
This is a highly influential measure that describes how much the planet will warm if carbon dioxide doubles and the Earth's climate adjusts to the new state of the atmosphere.
Studies have found a wide range of possibilities for this key measure — somewhere between 1.5 and 4.5°C, with 3°C.
Most scientists try to constrain ECS by looking at historical warming events.
For the last 25 years, the UN's Intergovernmental Panel on Climate Change (IPCC), the ultimate authority on climate science, has settled on a 'likely' range of 1.5°C to 4.5°C (2.7°F to 8.1°F).
Warming less than 1°C is 'extremely unlikely' and more than 6°C is considered 'very unlikely', the panel has concluded.
However, some scientists dispute this figure.
'Our approach may open up a new possibility for a future of model representation in climate models, which are data driven and are built "top-down," that is, by learning the salient features of the processes we are trying to represent,' Gentine said.
The researchers named their AI the Cloud Brain (CBRAIN).
It could skillfully predict many of the cloud heating, moistening, and radiative features that are essential to climate simulation.
CBRAIN may also improve estimates of future temperatures because global temperature sensitivity to CO2 is strongly linked to cloud representation.
This means the technology could potentially be used to predict greenhouse gas responses.
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|In spite of the importance of insects, data of their biology remains far away from complete. At present, however, there are a unit extremely exciting developments occurring among the sphere of insect analysis, as a result of the genomes from twenty four insect species have recently been sequenced, or area unit within the method of being sequenced. Among these insects area unit twelve fruit fly species happiness to the arthropod genus, the known being drosophila Meigen, that was the primary insect with a sequenced order. All the genomes from the insect species given during this figure are or are going to be sequenced with a minimum of Associate in nursing 8â9 times coverage i.e. the quality for a longtime sequenced order. This variety implies that solely only a few sequencing errors area unit left within the order draft, and additionally that there are a unit solely minor sequencing gaps. United will see in seven of the twelve fruit fly species have already reached the quality? Additionally to the order from D. melanogaster, 2 solely that from D. pseudoobscura has been printed, though info on the opposite fruit flies species is obtainable on the web. Scholarly journals provide a greater visibility in the growing scientific field. For presenting the on-going research and exciting discoveries within the realms of many Scholarly journals that have been started, which are playing a major role in enhancing the dissemination of natural and scientific knowledge. Scholarly Journals are journals which are respected for the research and information they provide about the topic they cover. Scholarly journals publish good quality articles by subjecting them to a thorough and careful peer review process. Articles are often anonymously reviewed by several other subject experts; this process is called "peer review process" and such a periodical is considered a "refereed journal. A scholarly journal presents rigorously peer-reviewed scientific articles in the following categories: original Research Articles, Communications, Reviews and Mini-Reviews, Commentaries and Letters to the Editor. OMICS Group International is one of the leading Open Access Publishers which is publishing 700+ peer-reviewed journals with the dramatic effort of editorial board members. Entomology, Ornithology and Herpetology: Current Research publishes original research articles, novel, and scientifically sound findings dealing with insects, birds and reptiles related to human health. | <urn:uuid:fa91e393-cc98-4901-a1a8-9011324ace8c> | 2.8125 | 467 | Knowledge Article | Science & Tech. | 23.276855 | 95,598,854 |
Biohabitats’ Leaf Litter
Vol. 3 Number 3
Thoughts on Roads
Like it or not, roads have become the arteries of our social and economic lives. Roads are necessary to transport goods and services to the marketplace, move people to and from their places of work, shopping, and social engagements, and serve as vital links to public health, safety and welfare.
Roads in the U.S. cover about 1% of the land area, an area equivalent to the state of South Carolina. It is estimated, however, that 20% of U.S. land area is directly affected ecologically by the road system. But in our quest to build roads to serve our burgeoning needs, biodiversity — that is the total diversity and variability of living things and the systems of which they are a part of — seems to have been left by the roadside. Like them or not, roads have a far reaching impact on biodiversity, both in terms of new construction and ongoing operations.
Typically when we think about roads and wildlife, the first thing that comes to mind is direct impacts to wildlife – road kill. It is estimated that in the U.S. approximately 1 million mammals are killed on roadways annually. If we consider insects, amphibians, birds and a host of other taxa, we are most likely looking at billions of species each year. In the United Kingdom, it is estimated that millions of birds and 20-40% of the UK’s breeding population of amphibians are believed to die each year on roads. Even the mere presence of a road can impact wildlife species. Dutch research for example, showed that out of 12 bird species examined, 7 exhibited reduced densities near roads than in similar habitats away from roads.
Roads are also responsible for changes in plant species composition, plant performance and soil nutrient levels along their right-of-ways. While direct impacts are important to consider, it is the indirect impact that may have the biggest effect on terrestrial, aquatic and avian species.
Fragmentation of habitat, water runoff pollution, air pollution, noise and artificial light pollution, along with the effects of spillages, litter and roadside management practices all can erode the quality of biodiversity and ecological integrity of the landscape.
While almost any form of road development will have some negative effect on the environment, there are many promising initiatives taking place throughout the world to reverse this trend. Many European countries are taking bold steps to initiate biodiversity action plans that address methods to reduce and mitigate road impacts on wildlife. These initiatives range from broad policy goals to preserve habitat connectivity (see Guiding Principles for Conducting Biodiversity Assessments for Road Projects) by promoting mass transportation projects and better land use planning, to specific mitigation techniques to allow wildlife movement across roads. Many U.S. transportation agencies are also beginning to incorporate both wildlife avoidance and mitigation strategies in road design.
In this issue of Leaf Litter, we highlight measures to protect, restore and mitigate wildlife habitat in relation to roads. We also interviewed Bethanie Walder, Executive Director of the Wildlands CPR. Wildlands CPR is becoming one of the leading authorities and sources of information on the ecological effects of roads and off-road vehicles.
Bethanie talks about some of the strategies being used to mitigate and restore ecosystems impacted by roads. Our Leaf Litter Survey on roads and their impacts to wildlife brought in some interesting comments, provocative thoughts and probing questions. Be sure to check it out. Finally, we have packed this issue of Leaf Litter with plenty of resources, information and links for you to take action. Remember the words of George Schultz: He who walks in the middle of the road gets hit from both sides.
– Keith Bowers, Principal
Further ReadingSustainability vs. Resiliency: Designing for a Trajectory of Change
Aloha: An unforgettable trip to the bathroom
Why do you feel ecological restoration is so important?
Election 2016: Down, but not out…
More From This AuthorBlurring the boundaries…
Novel Ecosystems in a New World Order
Restoring the Future
Restoration at Different Scales | <urn:uuid:881d570f-3f52-4afd-9951-42668a398bde> | 3.46875 | 846 | Personal Blog | Science & Tech. | 36.744732 | 95,598,869 |
An international team of researchers, including scientists of the Max Planck Institute of Immunobiology and Epigenetics, has sequenced and analysed the genome of the elephant shark.
The immune system of the elephant shark is simpler than many other vertebrates studied so far. The present studies also explain, why cartilaginous fishes do not generate human-like bones
Comparison of the elephant shark genome with human and other vertebrate genomes has revealed why the skeleton of sharks is made up largely of cartilage and not bone like the human skeleton and that the immune system of the shark is much simpler than that of humans. The findings of Byrappa Venkatesh and his coworkers are published in the latest issue of the scientific journal, Nature.
An unexpected finding of the immune system analysis was that sharks appear to lack special types of so-called T-helper lymphocytes, that – until now – were considered to be essential for defence against viral/bacterial infections and preventing autoimmune reactions such as diabetes and rheumatoid arthritis in vertebrates.
Despite this seemingly primitive organization of the immune system, sharks exhibit robust immune defences and are long-lived. “The structure of the immune system of the elephant shark is very different from mammals,” said Thomas Boehm, co-author and director at the Max Planck Institute of Immunobiology and Epigenetics in Freiburg, Germany. “It is obvious that sharks can efficiently deal with all kinds of infections without this particular cell type. This indicates that nature can come up with different solutions to the same problem,” stated Boehm.
What happens when T-helper cells are being destroyed can be observed in AIDS patients, who succumb to viral and bacterial infections. Up to now, it was assumed that cells are essential for an immune system. The new results are challenging this long-held notion and open up an unprecedented avenue towards the development of non-intuitive strategies to modulate the immune functions of humans.
The researchers also investigated why cartilaginous fishes, including the elephant shark, are unable to replace cartilage with bone like humans and other bony vertebrates. Genome analysis was able to highlight a family of genes that are absent in sharks but present in all bony vertebrates and are critical for bone formation. When the researchers inactivated these genes in bony fishes such as the zebrafish, calcification did not occur. This finding is a strong indication that the investigated gene family could be a starting point for a better understanding of bone diseases such as osteoporosis.
In addition, the study revealed that the elephant shark genome is the slowest evolving among all vertebrates. The elephant shark even beats the coelacanth, also called “the living fossil”, that has recently been shown to evolve extremely slowly. Therefore, the elephant shark is probably the best proxy for the ancestor of all jawed-vertebrates that became extinct a long time ago.
Cartilaginous fishes (comprising sharks, rays, skates and chimaeras) are the oldest living group of jawed-vertebrates that diverged from bony vertebrates about 450 million years ago. The elephant shark (Callorhinchus milii) is a chimaera that inhabits temperate waters of the continental shelves off southern Australia and New Zealand, at depths of 200 to 500 meters. From approximately 1,000 species of cartilaginous fishes, elephant shark was chosen as a model because of its relatively compact genome which is one third the size of the human genome.
The elephant shark genome project was funded mainly by the National Institutes of Health (NIH), USA. It is a collaborative effort of scientists from 12 international institutions, including the Max Planck Institute of Immunobiology and Epigenetics (MPI-IE) in Freiburg, Germany. Viruses, bacteria and other parasites are a continuous threat to all living beings. Therefore, most of them possess elaborate defence strategies to combat these unwanted intruders. At the Max Planck Institute of Immunobiology and Epigenetics, Thomas Boehm studies the evolution of the immune system and its development and function during lifetime of animals. For his fundamental work on development, differentiation and evolution of immune systems, Thomas Boehm is awarded the prestigious Ernst Jung Award for Medicine 2014.
ContactDr. Thomas Boehm
Dr. Thomas Boehm | Max-Planck-Institute
NYSCF researchers develop novel bioengineering technique for personalized bone grafts
18.07.2018 | New York Stem Cell Foundation
Pollen taxi for bacteria
18.07.2018 | Technische Universität München
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
18.07.2018 | Materials Sciences
18.07.2018 | Life Sciences
18.07.2018 | Health and Medicine | <urn:uuid:bd83b2f0-7f56-48f3-b8f2-11d1dcb98b6d> | 3.359375 | 1,535 | Content Listing | Science & Tech. | 31.739666 | 95,598,871 |
posted by Rachel
A string fixed at both ends is 9.31 m long and has a mass of 0.125 kg. It is subjected to a tension of 100.0 N and set oscillating.
(a) What is the speed of the waves on the string?
(b) What is the longest possible wavelength for a standing wave?
(c) Give the frequency of that wave.
wave velocity=sqrt (tension/(mass/length)
longest wavelength: 1/2 Lambda = 9.31 m long
he equation of a transverse wave on a string is
y = (4.8 mm) sin[(14 m-1)x + (440 s-1)t]
The tension in the string is 10 N. (a) What is the wave speed? (b) Find the linear density of this string. | <urn:uuid:f5e3dc0e-a4cd-4e55-8bec-0e0f6afdc1fc> | 3.375 | 182 | Q&A Forum | Science & Tech. | 106.413139 | 95,598,872 |
+44 1803 865913
Edited By: PM Huang and GR Gobran
400 pages, no illustrations
From the publisher's announcement:
The rhizosphere in soil environments refers to the narrow zone of soil influenced by the root and exudates. Microbial populations in the rhizosphere can be 10 ? 100 times larger than the populations in the bulk soil. Therefore, the rhizosphere is bathed in root exudates and microbial metabolites and the chemistry and biology at the soil-root interface is governed by biotic (plant roots, microbes) and abiotic (physical and chemical) interactions.
The research on biotic and abiotic interactions in the rhizosphere should, thus, be an issue of intense interes for years to come. This book, which consists of 15 chapters, addresses a variety of issues on fundamentals of microscopic levels and the impact on food chain contamination and the terrestrial ecosystem.
It is an essential reference work for chemists and biologists studying environmental systems, as well as earth, soil and environmental scientists.
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Using underwater 360º virtual reality to raise awareness of the beauty,
fragility, and importance of the world’s oceans.
Using high definition underwater 360º virtual reality to raise awareness of the beauty, the fragility, and the critical importance of the world’s oceans.
The world’s oceans and the living creatures that inhabit it continue to deteriorate. Coral bleaching is spreading at an alarming rate, vast plumes of floating garbage are continually being discovered, plastics are polluting oceans and drinking water, and once abundant fish stocks are disappearing. When oceans are in trouble, humans are too. Millions of people around the globe depend on the oceans for food.
Fifty percent of the oxygen we breathe comes from phytoplankton in the ocean. As the oceans warm, phytoplankton populations are significantly affected and the ocean life that depends on the phytoplankton decline. As carbon dioxide increases in the atmosphere, the ocean absorbs the gas and becomes acidified, which destroys many corals and other organisms. The oceans are in serious trouble.
photo credit: Greg Asner
It is imperative that we help people understand the issues involved in a way that is strongly engaging. Showing the beauty and the fragility of the oceans, by using awe-inspiring technology, creates a deeper appreciation of the issues involved and a desire to conserve the world’s oceans.
A diver using the 360 Boxfish Research underwater camera.
The Lions of Gir Foundation (named after the near extinct Asiatic lions of the Gir Forest of India) plans to produce very high resolution, short duration, 360º videos that are converted for virtual reality using the Oculus Go VR goggles. The images are shot underwater by scientists and underwater photographers for use by STEM programs, classroom science education programs, museums, and aquariums around the globe.
The videos will be provided to educational institutions to be seen by as many people as possible. The camera will be loaned to scientists and photographers to help us gather content from the oceans of the world. In addition to the VR goggles the 360º videos can be viewed online, on mobile devices, or on a computer screen.
2018 has been declared the International Year of the Reef, and it couldn’t have come at a more important time. Coral reefs are in crisis – they could disappear on our watch and potentially within in our lifetime. It’s not too late – together, we can solve this crisis. But first, we need to raise awareness. | <urn:uuid:19667338-d3ae-4a93-8986-c1d65e08df16> | 3.1875 | 520 | News (Org.) | Science & Tech. | 38.208748 | 95,598,903 |
Adaptation to Coastal Erosion in Vulnerable Areas, is a coastal protection activity implemented in Senegal by the Centre de Suivi Ecologique (CSE). The activity is to protect the coastal areas of Rufisque, Saly and Joal – all just outside Senegal’s capital Dakar – against further erosion caused by sea level rise and storm surges.
The activity is one of the first of its type to receiving funding from the Adaptation Fund, which finances projects and programmes that help developing countries to adapt to the negative effects of climate change. Started in January 2011, the activity aims to reduce exposure to climate change impacts on the coast by protecting houses and coastal infrastructure - such as fishing docks, fish processing plants and even tourism - that are threatened by erosion and salt-water intrusion. Some measures the activity introduced include anti-salt dikes to mitigate salination of agricultural lands and sea defences to prevent coastal erosion.
The activity also incorporates development of coastal management policies and regulations.Senegal has a high incidence of climate-sensitive economic activities, including farming and other businesses. This is due to the high population density and the concentration of almost all economic activities in coastal areas. In Saly, for instance, within a span of just four years, the beach has been entirely submerged, prompting the largest tour operator to depart. The loss of tourism revenue has lead to a decline in household incomes as well as livelihood opportunities for many local craftsmen.
Coastal urban areas are threatened by rising sea levels and increased oceanic activity. Between the coastal urban zone and the Atlantic Ocean, the coastline is a thin strip that increasing coastal forces are quickly eroding. The beach where the Senegalese national soccer team practiced some years ago no longer exists. A hotel owner, who until recently used to offer “a hotel and a beach,” now can only sell “a hotel and an ocean”.
Adaptation to Coastal Erosion in Vulnerable Areas is prioritized, implemented, and executed by local institutions and is strongly linked to the communities themselves, particularly to women. Two of the activity’s implementing entities are local NGOs - Green Senegal, and Dynamiques-Femmes, an association of women and youth. The involvement of local communities is strongly leveraged to compliment the infrastructure-based outputs with training and awareness-raising programmes.
Mitigation / Adaptation
Approximately 812 awareness-raising sessions have been organized in the two years since the activity began, which targeted various segments of the community. Training sessions have also been organized, focussing on organizational development, adaptation to coastal erosion and the impact of climate change on the fishing community. Around 500 people have been trained to date, including include women's associations, local elected officials, and neighbourhood committees. As a result, a network of coastal actors has been established, where community members better understand the impacts of climate change and are better able to face them.
In addition, 104 radio programs were produced. The programmes dealt with issues such as climate change and coastal erosion.
Social and environmental benefits
In Joal, a more than 3,000 meter anti-salt dike has been built, which will help reclaim 17 hectares of rice farm land. The drying area for fishery products was also rehabilitated. Its management has been entrusted to a local committee composed of women fish sellers with the support of the municipality, benefiting some 100 women. The facility will also help protect houses, hotels and fish processing areas from storm surges.
Similarly, the 730 metre dike in Rufisque protects the neighbourhood of Thiawelene from storm surges.
In Rufisque, the construction of a seawall along the coastline, will protect houses that are being threatened by coastal erosion, a problem which effects the town's historical heritage (as many colonial houses have been effected). As waste water management is also a problem, the NGO Green Senegal is raising awareness of residents on best practices for waste water management.
The preservation of hotels and other tourist infrastructures, as well as the fishing dock in Saly will help maintain at least three thousand (3,000) direct jobs and nine thousand (9,000) indirect, generated by tourism and fishing.
Potential for scaling-up and replication
The activity has received considerable attention from both developing and developed countries, and from different types of stakeholder groups. It is already being replicated in other countries, thereby leading to its scaling up world-wide. Some of the first projects to replicate the modality include an agriculture sector project in Uruguay, a multi-sector programme in Jamaica and the development of a coastal development project in Benin. The implementing agency of the project has been repeatedly invited to present their experience in adaptation related workshops in neighbouring countries, as well as farther afield, such as Ethiopia, South Africa, Thailand and Philippines.
The direct access modality gives countries project ownership and has an enormous potential for global transformational change in how adaptation is implemented world-wide, cost-effectively and in a country-driven manner, thereby bringing about a sustainable long-term impact. In the case of Senegal, this has turned out to reduce administrative costs. The low administrative costs of the project directly translate into making better use of allocated funds to achieve the scale of results. The fact that the level of direct international supervision is replaced with supervision by a national agency that went through a rigorous accreditation process using internationally accepted standards, has catalyzed a change in institutional dynamic by reducing distance between levels of hierarchy. This has greatly facilitated the collaboration of various types of governmental and non-governmental organizations, including a sizable community of artisanal fishermen and fish-processing industries, tourism operators, agricultural producers on the inland side of the coastal zone, a women’s group and an environmental non governmental organization. | <urn:uuid:02ca67bf-071e-4d97-b4ea-97fe2bbcaead> | 3.125 | 1,190 | Knowledge Article | Science & Tech. | 15.858665 | 95,598,913 |
Public talk on climate change, coastal hazards and sea level
Public talk on climate change, coastal hazards and sea level rise
Hawke’s Bay people will get the chance to learn more about New Zealand’s latest coastal hazards and sea level science and how the impacts can be managed.
East Coast LAB (Life at the Boundary) is hosting a public talk by Dr Rob Bell (NIWA), Dr Judy Lawrence (Victoria University) and Dr. Dan Zwartz (Ministry for the Environment) on climate change, coastal hazards and sea level rise science and how to manage the impacts of them.
Dr. Rob Bell says, “Climate change will increase the risk of coastal hazards around New Zealand as sea level rises and we need to be prepared for this change.”
Dr. Judy Lawrence says, “Across New Zealand we need to adopt some new approaches to support iwi/hapū and coastal communities in preparing for change that is sustainable over the long term”
Both researchers were authors of the updated Ministry for the Environment’s Coastal Hazards and Climate Change Guidance.
The talk will be held on Thursday 19 July at 7pm at the LAB at the National Aquarium of New Zealand. The talks will last for 60 minutes, followed by time for questions and discussion.
Kate Boersen of East Coast LAB says, “We want to help ensure communities along the East Coast are aware of the impacts of climate change on natural hazards and people and on possible ways to manage these impacts.”
Similar events and workshops are being held across the country to help councils and communities implement the guidance. These are being supported by the Ministry for the Environment, in partnership with councils, the Deep South National Science Challenge, the NZ Coastal Society and NIWA.
East Coast LAB (Life at the Boundary) is a project, which makes it easy and exciting to learn more about natural hazards and how they affect us living on the coast near the Hikurangi plate boundary. | <urn:uuid:b7facefa-8d48-4b9f-882e-2059968e3976> | 2.53125 | 415 | News Article | Science & Tech. | 45.453252 | 95,598,921 |
7.4 years ago by
This is an unusual and interesting question. I think it might help to generalize it:
- Given a list of species, how can I find those that have DNA sequence?
- or how can I find a specific DNA sequence for a list of species?
To start with the second question: which sequence(s) do you want to use to build the tree? It's possible that a specialized database exists; for example, the SILVA rRNA database might be useful if you wanted to use 18S rDNA sequence.
For the first question, my starting point would be the NCBI. There are several ways into the problem. You might start with the taxonomy resource, by searching for species. Here, for example, is a page for zebrafish: in the box on the right are links to nucleotide sequences for that organism. Or you might want to search the Gene or Nucleotide databases using organism + gene name as a query, for example:
"Homo sapiens"[ORGN] AND GUCA2B[GENE]
Once you've identified a good search strategy you will want to automate search and retrieval, for which you'll need NCBI EUtils and some programming ability (in e.g. Perl, Ruby or Python). | <urn:uuid:405d6305-fbfb-492b-85d9-110d2c658bb9> | 3.140625 | 269 | Q&A Forum | Science & Tech. | 60.812966 | 95,598,925 |
Habitat preference and spatial distribution of Guiana dolphins (Sotalia guianensis) in Norte Bay, southern Brazil, was studied from 2001 to 2005. Boat surveys (N ¼ 91) were made to evaluate the spatial distribution of the dolphins. Seven habitat variables were integrated into a geographical information system, and habitat preference was tested using the ‘Neu method’ and a habitat index. The Guiana dolphins did not use all habitat types in the same proportion as were available. Areas used more intensively included, in order of importance: (1) areas with a steep sloping sea-floor; (2) areas further from urban areas; (3) areas further from mangroves; (4) areas near the mouth of the bay; (5) shallow water areas; (6) areas of clayey-silt sediments; and (7) areas close to shore. From 2001 to 2005 there was a shift in spatial distribution and habitat use by the dolphins. The low frequency of use of areas close to urban encroachment and its related impacts to the marine environment raises concern about the coastal habitat destruction. The Guiana dolphin may be considered a habitat specialist, despite its wide latitudinal distribution in the western Atlantic Ocean. The ecological niche of the species may be defined by a narrow strip of shallow coastal waters (mostly , 30 m) bordering the coastline. The shift in the spatial use was probably linked with changes in the abundance of important prey of the species and possibly was caused by the collapse of a fish stock in the study area region. Different habitats may favour different assemblages of prey and consequently different foraging strategies by the dolphins. Human-related habitat alterations throughout the range of this species are likely to affect dolphins’ ecology in many ways and, thus, must be evaluated and mitigated to conserve their critical habitats.
Mendeley saves you time finding and organizing research
Choose a citation style from the tabs below | <urn:uuid:6c792d38-4439-44a1-866e-62c1332d7298> | 3.734375 | 396 | Academic Writing | Science & Tech. | 28.73923 | 95,598,947 |
mashlib and Data Browser
The mashlib (
mashlib.js) is a solid-compatible data mashup library. One major
use of it is as a data browser for a personal data store.
The mashlib has been used before originally in various apps in specific data interaction in different domains. It has been used in a browser extension (in Firefox and later Chrome) to add data-handling capacity as native to the browser itself. Currently it is used as the core as aort or poor persons browser extension, the data browser, which loads the library and then tries to work as though the browser had been extended to understand data
The data browser
How does the data browser work?
- The user goes with a normal web browser to access some data object (like a to-do list, say).
- The server sees the browser doesn't understand the data natively.
- The server sends back a little placeholder HTML file,
databrowser.html, instead of the data.
databrowser.htmlfile loads the
mashlib.jsthen re-requests the original data, but accepting data formats.
- The server supplies the actual data of the to-do list or whatever it was.
mashlib.jscode provides an editable visualization on the data.
The mashlib human interface is read-write: where the user is allowed to edit: it lets them edit the data and create new things. It is live, in that often the data browser signed up (using a websocket) for any changes which other users make, so users' screens are synchronized.
History: Why "Mashlib"?
What is a data mashup? A mashup is a web page which is built out of data coming from more than one source.
Mashups are important because they are fun but because fundamentally the value
of data is much greater when data of one source is combined with linked data from another,
because that is where you can get extra insights. My TED talk on open data examples has some examples. Data mashups were all the rage back 2012-2017, although the browser's Same Origin Policy in many cases makes them hard to do or impossible in a web app, as the data access is blocked by the browser code.
The mashlib started life motivated by the drive to build quick visualizations of data from different sources. Typically, documents or query results are all loaded into the quadstore, so the relationships between different things can be visualized. The "tabulator" project developed the original mashlib.
Progressively, the mashlib evolved to allow types of data for personal information management (contacts, etc) and social (chat, shared documents, issue tracking, music, photos) and also as a file browser for a Solid-compatible personal data store (files, folders, and sharing). Now, the mashlib is a general-purpose tool for doing all kinds of useful things.
It is an extensible platform, and is never finished. Do help!
The data browser should be a complete web-based operating system for any new computer or data store.
You should be able to set the data browser up for any existing folders you have full of things like photos and music, and it should let you listen to them, look at them, and share them very flexibly with anyone in the world.
The data browser should be modular, loading new code modules in real time as a function of a user's preferences for handling different types of data with different new data browser applets, be it finance, fitness, or fishing.
The data browser should allow people to create, bit by bit, a web of social linked data of their work and their play, and their lives.
- Here is the Travis build space | <urn:uuid:6db3cb52-db08-4378-a70a-ba712c3214be> | 2.546875 | 788 | About (Org.) | Software Dev. | 47.971092 | 95,598,975 |
"This planet is a complete mystery," says astronomer David Latham of the Harvard-Smithsonian Center for Astrophysics (CfA). "We don't know how it formed or how it got to where it is today. What we do know is that it's not going to last forever."
"Kepler-78b is going to end up in the star very soon, astronomically speaking," agrees CfA astronomer Dimitar Sasselov.
Not only is Kepler-78b a mystery world, it is the first known Earth-sized planet with an Earth-like density. Kepler-78b is about 20 percent larger than the Earth, with a diameter of 9,200 miles, and weighs almost twice as much. As a result it has a density similar to Earth's, which suggests an Earth-like composition of iron and rock.
The tight orbit of Kepler-78b poses a challenge to theorists. When this planetary system was forming, the young star was larger than it is now. As a result, the current orbit of Kepler-78b would have been inside the swollen star.
"It couldn't have formed in place because you can't form a planet inside a star. It couldn't have formed further out and migrated inward, because it would have migrated all the way into the star. This planet is an enigma," explains Sasselov.
According to Latham, Kepler-78b is a member of a new class of planets recently identified in data from NASA's Kepler spacecraft. These newfound worlds all orbit their stars with periods of less than 12 hours. They're also small, about the size of Earth. Kepler-78b is the first planet in the new class to have its mass measured.
"Kepler-78b is the poster child for this new class of planets," notes Latham.
The team studied Kepler-78b using a newly commissioned, high-precision spectrograph known as HARPS-North, at the Roque de los Muchachos Observatory on La Palma. They coordinated their work with a second, independent team using the HIRES spectrograph at the Keck Observatory. The teams' measurements agreed with each other, increasing their confidence in the result.
Kepler-78b is a doomed world. Gravitational tides will draw it even closer to its star. Eventually it will move so close that the star's gravity will rip the world apart. Theorists predict that Kepler-78b will vanish within three billion years.
Interestingly, our solar system could have held a planet like Kepler-78b. If it had, the planet would have been destroyed long ago leaving no signs for astronomers today.
Kepler-78b orbits a Sun-like G-type star located 400 light-years from Earth in the constellation Cygnus.
Headquartered in Cambridge, Mass., the Harvard-Smithsonian Center for Astrophysics (CfA) is a joint collaboration between the Smithsonian Astrophysical Observatory and the Harvard College Observatory. CfA scientists, organized into six research divisions, study the origin, evolution and ultimate fate of the universe.
For more information, contact:David A. Aguilar
Christine Pulliam | EurekAlert!
What happens when we heat the atomic lattice of a magnet all of a sudden?
18.07.2018 | Forschungsverbund Berlin
Subaru Telescope helps pinpoint origin of ultra-high energy neutrino
16.07.2018 | National Institutes of Natural Sciences
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
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19.07.2018 | Life Sciences | <urn:uuid:86c3a40b-2169-4862-9281-418c462ee3cc> | 3.8125 | 1,300 | Content Listing | Science & Tech. | 50.212952 | 95,598,982 |
Lcm of three numbers
What is the Lcm of 120 15 and 5
Leave us a comment of example and its solution (i.e. if it is still somewhat unclear...):
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Next similar examples:
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Janko bought pencils for 35 cents each. Neither he nor the salesperson had small coins just a whole € 1 coin. At least how many pencils had to buy to pay for the whole euros?
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- Tram lines
Trams of five lines driven at intervals of 5,8,10,12 and 15 minutes. At 12 o'clock come out of the station at the same time. About how many hours again all meet? How many times have earch tram pass for this stop? | <urn:uuid:c3bc44e8-7379-4bc6-bcb2-ec2c2d447de1> | 3.3125 | 764 | Tutorial | Science & Tech. | 79.894187 | 95,599,007 |
Compared to their mainland relatives, Channel Islands foxes are dwarves with little genetic variation. In fact, one of these island populations may be the least genetically variable population of all wild animals, according to findings published in Current Biology last week.
Channel Island foxes (Urocyon littoralis) evolved from gray foxes brought over to the islands by humans some 7,000 years ago. Nowadays, they live on six of Californias Channel Islands. Theyre about two-thirds the size of foxes living on mainland southern California, and like many island species, theyre not really afraid of humans. These isolated island populations have persisted for thousands of years at extremely small population sizes. But in the last couple of decades, four of these subspecies from San Miguel, Santa Rosa, Santa Cruz, and Santa Catalina were listed as endangered after predation from non-native golden eagles and the introduced canine distemper virus caused catastrophic declines.
A team led by UCLAs Robert Wayne sequenced the genomes of Channel Island foxes representing all six populations as well as one mainland gray fox (Urocyon cinereoargenteus) from southern California using DNA samples collected in 1988 before their recent declines, with the plan toformamodel for long-term conservation of small endangered populations.
Not only do island foxes have drastically decreased genetic variation, they also have high levels of deleterious mutations compared to the gray fox. That suggests selection hasnt purged their genome of harmful variants. Specifically, island foxes show a 3- to 84-fold reduction in whats called heterozygosity. Thats when an individual inherits different variants of a gene from its parents.
In particular, the San Nicolas Island fox showed the most extreme reduction of heterozygosity: They have a near absence of variation. After sequencing the genomes of two San Nicolas individuals, the team found that they were nearly identical. This unique instance of “genomic flatlining” likely shouldn’t bode well, yet this small population has managed to survive.
“The degree to which the San Nicolas foxes have lost genetic variation is remarkable, upholding a previous observation that they may be the least genetically variable population of wild animals known,” Wayne said in a statement. “It suggests that under some conditions, genetic variation is not absolutely essential for the persistence of endangered populations.” | <urn:uuid:16a58cdd-f650-44b3-a057-19ddf66f7246> | 4 | 493 | News Article | Science & Tech. | 20.055267 | 95,599,015 |
JAVA SCRIPT INJECTION:-
- Injection Basics
- Cookie Editing
- Form Editing
I. Injection Basics:
You should get a little dialog box that says “Hello, World”. This will be altered later to have more practical uses. You can also have more than one command run at the same time:
This would pop up a box that said ‘Hello’ and than another that says ‘World’.
2. Cookie Editing
First off, check to see if the site you are visiting has set any cookies by using this script:
This will pop up any information stored in the sites cookies. To edit any information, we make use of the void(); command.
This command can either alter existing information or create entirely new values. Replace “Field” with either an existing field found using the alert(document.cookie); command, or insert your very own value. Then replace “myValue” with whatever you want the field to be.
Would either make the field “authorized” or edit it to say “yes”… now whether or not this does anything of value depends on the site you are injecting it on.
It is also useful to tack an alert(document.cookie); at the end of the same line to see what effect your altering had.
3. Form Editing
Every form on a given webpage (unless named otherwise) is stored in the forms[x] array. where “x” is the number, in order from top to bottom, of all the forms in a page. Note that the forms start at 0, so the first form on the page would actually be 0, and the second would be 1 and so on.
Lets take this example:
<form action=”http://www.website.com/submit.php” method=”post”>
<input type=”hidden” name=”to” value=”firstname.lastname@example.org”>
Note: Since this is the first form on the page, it is forms
Say this form was used to email, say vital server information to the admin of the website. You can’t just download the script and edit it because the submit.php page looks for a referrer. You can check to see what value a certain form element has by using this script.
This is similar to the alert(document.cookie); discussed previously. In this case, It would pop up an alert that says “email@example.com”
So here’s how to Inject your email into it. You can use pretty much the same technique as the cookies editing shown earlier:
This would change the email of the form to be “firstname.lastname@example.org”. Then you could use the alert(); script shown above to check your work. Or you can couple both of these commands on one line.
To move things around on the webpage | <urn:uuid:dd5c4d72-7f83-443b-8678-2e22a4ba815b> | 2.96875 | 631 | Tutorial | Software Dev. | 67.11505 | 95,599,022 |
Statistics Definitions > Homogeneity & Homogeneous Data
What is Homogeneity?
A data set is homogeneous if it is made up of things (i.e. people, cells or traits) that are similar to each other. For example a data set made up of 20-year-old college students enrolled in Physics 101 is a homogeneous sample.
What is Homogeneous Sampling?
In homogeneous sampling, all the items in the sample are chosen because they have similar or identical traits. For example, people in a homogeneous sample might share the same age, location or employment. The selected traits are ones that are useful to a researcher. It is a type of purposive sampling and is the opposite of maximum variation sampling.
Homogeneous samples tend to be:
- Made up of similar cases.
The opposite of a homogeneous sample is a heterogeneous sample. For this example, you might have a heterogeneous sample of 18-21 year old students in history 112, chemistry 211 and physics 101. The same is true for a heterogeneous population (all items in the population have different characteristics) and a homogeneous population (all items in the population have the same characteristics).
Homogeneous in More General Terms
In data analysis, a set of data is also considered homogeneous if the variables are one type (i.e. binary or categorical); if the variables are mixed (i.e. binary + categorical), then the data set is heterogeneous.
While it’s common in statistics to use “homogeneous” to mean the general sense of being the same, a data set can be analyzed mathematically to see if the data set is homogeneous. There are several ways to achieve this:
- Compare boxplots of the data sets.
- Compare descriptive statistics (especially the variance, standard deviation and interquartile range.
- Run a statistical test for homogeneity.
Running statistical tests for homogeneity becomes important when performing any kind of data analysis, as many hypothesis tests run on the assumption that the data has some type of homogeneity. For example, an ANOVA test assumes that the variances of different populations are equal (i.e. homogeneous).
One example of a test is the Chi-Square Test for Homogeneity. This tests to see if two populations come from the same unknown distribution (if they do, then they are homogeneous). The test is run the same way as the standard chi-square test; the Χ2 statistic is computed, and the null hypothesis (that the data comes from the same distribution) is either accepted or rejected.
Homogeneity of variance (also called homoscedasticity) is used to describe a set of data that has the same variance. Visually, the data will have the same scatter on a scatter plot. If data does not have the same variance, it will show a heteroscedastic (“not the same”) scatter pattern.
If you prefer an online interactive environment to learn R and statistics, this free R Tutorial by Datacamp is a great way to get started. If you're are somewhat comfortable with R and are interested in going deeper into Statistics, try this Statistics with R track.Comments? Need to post a correction? Please post on our Facebook page. | <urn:uuid:9efe01e4-a1d1-4add-894c-3284de29889f> | 4.375 | 680 | Knowledge Article | Science & Tech. | 37.513642 | 95,599,031 |
When the ice melts, as was the case during the ice minimum in 2012, these algae sink rapidly to the bottom of the sea at a depth of several thousands of metres. Deep sea animals such as sea cucumbers and brittle stars feed on the algae, and bacteria metabolise what’s left, consuming the oxygen in the sea bed.
Several groups take possession of the sea ice habitat of every ice station: water samples from the melting pools, the ice itself and the water beneath – everything is investigated for plants, animals and microorganisms. © Mar Fernandez, Alfred Wegener Institute
This short-term reaction of the deep sea ecosystem to changes in sea ice cover and ocean productivity has now been published in the scientific journal Science by a multidisciplinary team of researchers around Prof. Dr. Antje Boetius from the Alfred Wegener Institute (AWI), Helmholtz Centre for Polar and Marine Research.
Scientists and technicians from twelve nations travelled the Central Arctic on the research icebreaker Polarstern in the late summer of 2012. In and under the ice they used a large number of ultra-modern research devices and methods such as camera-guided sampling devices and an under-ice remotely operating vehicle (ROV). Prof. Antje Boetius, who leads the Helmholtz-Max Planck Research Group on Deep-Sea Ecology and Technology has a first answer to the all-important question of how the Arctic is changing due to warming: “Far quicker than has so far been expected! The seabed at a depth of more than 400 metres was littered with clumps of ice algae which had attracted lots of sea cucumbers and brittle stars“, explains the microbiologist.
The algal deposits with diameters of up to 50 centimetres covered up to ten per cent of the seabed. The researchers were able to count them using an Ocean Floor Observation System (OFOS). Also for the first time in the ice-covered Arctic, the Helmholtz-Max Planck researcher Dr. Frank Wenzhöfer was able to measure the bacterial and faunal oxygen consumption directly in the deep sea using micro-sensors. And life was thriving under the algae cover: bacteria had started to decompose the algae as evident from a greatly reduced oxygen content in the sediment. By contrast, the sea bed in the adjacent algae-free areas was aerated down to a depth of 80 centimetres and had virtually no algal residues.
But where do the large quantities of algae on the deep-sea floor come from? Plants cannot grow in 4000 m water depth because there is no light. Using an ROV, the researchers found lots of remains of ice algae everywhere under the sea ice. “It has been known for some time that diatoms of the type Melosira arctica can form long chains under the ice. However, such a massive occurrence has so far only been described for coastal regions and old, thick sea ice “, explains Boetius. When planning the expedition three years ago the researchers proposed the hypothesis that ice algae could grow faster under the thinning sea ice of the Central Arctic. And the observations now published in the scientific journal Science support their hypothesis: at 45 per cent, the ice algae were responsible for almost half of the primary production in the Central Arctic Basin. The remaining primary production was attributable to other diatoms and nanoplankton which live in the upper layers of the water column.
Normally, the small phytoplankton cell sinks only very slowly through the water column and is largely consumed already within the ocean surface layer. By contrast, the long chains of algae formed by Melosira arctica are heavy and can quickly sink to the bottom of the sea. In this way they exported more than 85 per cent of the carbon fixed by primary production from the water surface to the deep sea in summer 2012, just before the expedition. The researchers suppose that the algae had actually grown recently because they found only one-year old ice in the Central Arctic, and because the algae extracted from the guts of sea cucumbers were still able to photosynthesise upon return to the ship’s laboratory. The good nutritional state of the sea cucumbers was also evidence of the massive food supply: the zoologist Dr. Antonina Rogacheva of the P.P. Shirshov Institute of Oceanology found that the animals were larger than normal and with highly developed reproductive organs – an indication that they had been eating abundantly for some two months.
The sea ice physicists on board investigated why ice algae are able to thrive beneath the thinning Arctic sea ice, and how they may also lose their habitat quickly due to the increasing ice melt. They determined the ice thickness with an electromagnetic probe dragged by a helicopter and by ice drillings. They also used an underwater robot (ROV) to view the ice from below and to measure how much light penetrates through the ice. Dr. Marcel Nicolaus from the Alfred Wegener Institute explains: “At the end of the summer we still found a lot of ice algae remains, and could quantify them by using an under-ice ROV. The increasing cover by melt ponds permits more light to permeate the ice, and makes the algae grow faster.” (see also Press Release dated 15 January 2013: http://bit.ly/V1BwmJ). However, since the ice has become so much thinner in recent years, and the Arctic so much warmer, the ice algae will melt out more quickly from the ice and sink.
“We were able to demonstrate for the first time that the warming and the associated physical changes in the Central Arctic cause fast reactions in the entire ecosystem down to the deep sea“, summarises lead author Boetius. The deep sea has so far been seen as a relatively inert system affected by global warming only with a considerable temporal delay. The fact that microbial decomposition processes fueled by the algal deposits can generate anoxic spots in the deep sea floor within one season alarms the researcher: “We do not know yet whether we have observed a one-time phenomenon or whether this high algal export will continue in the coming years.“ Current predictions by climate models assume that an ice-free summer could occur in the Arctic in the next decades. Boetius and her team warn: “We still understand far too little about the function of the Arctic ecosystem and its biodiversity and productivity, to be able to estimate the consequences of the rapid sea-ice decline.“The title of the original publication is:
The work was partly financed by the Advanced Investigator Grant ERC „Abyss“ from the European Research Council.Participating institutions:
Full list of the RV Polarstern ARK-XXVII/3 Shipboard Science Party can be found in the original publication.Your scientific contacts are:
Follow the Alfred Wegener Institute on Twitter (https://twitter.com/#!/AWI_de) and Facebook (http://www.facebook.com/AlfredWegenerInstitut) to obtain all current news and information on everyday stories from the life of the Institute.
The Alfred Wegener Institute conducts research in the Arctic and Antarctic and in the high and mid-latitude oceans. The Institute coordinates German polar research and provides important infrastructure such as the research icebreaker Polarstern and stations in the Arctic and Antarctic to the international scientific world. The Alfred Wegener Institute is one of the 18 research centres of the Helmholtz Association, the largest scientific organisation in Germany.
Ralf Röchert | idw
Further reports about: > Antarctic Predators > Arctic Ocean > Arctic sea ice > Deep-sea > Marine science > Max Planck Institute > Oceanology > Polar Day > Polar and Marine Research > Polarstern > Rapid Product Development > Venus Express > brittle stars > deep sea > icebreaker Polarstern > information technology > sea cucumbers > sea floor > sea ice > water column
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....
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The density, or more precisely, the volumetric mass density, of a substance is its mass per unit volume. The symbol most often used for density is ρ (the lower case Greek letter rho), although the Latin letter D can also be used. Mathematically, density is defined as mass divided by volume:
where ρ is the density, m is the mass, and V is the volume. In some cases (for instance, in the United States oil and gas industry), density is loosely defined as its weight per unit volume, although this is scientifically inaccurate – this quantity is more specifically called specific weight.
For a pure substance the density has the same numerical value as its mass concentration. Different materials usually have different densities, and density may be relevant to buoyancy, purity and packaging. Osmium and iridium are the densest known elements at standard conditions for temperature and pressure but certain chemical compounds may be denser.
To simplify comparisons of density across different systems of units, it is sometimes replaced by the dimensionless quantity "relative density" or "specific gravity", i.e. the ratio of the density of the material to that of a standard material, usually water. Thus a relative density less than one means that the substance floats in water.
The density of a material varies with temperature and pressure. This variation is typically small for solids and liquids but much greater for gases. Increasing the pressure on an object decreases the volume of the object and thus increases its density. Increasing the temperature of a substance (with a few exceptions) decreases its density by increasing its volume. In most materials, heating the bottom of a fluid results in convection of the heat from the bottom to the top, due to the decrease in the density of the heated fluid. This causes it to rise relative to more dense unheated material.
The reciprocal of the density of a substance is occasionally called its specific volume, a term sometimes used in thermodynamics. Density is an intensive property in that increasing the amount of a substance does not increase its density; rather it increases its mass.
In a well-known but probably apocryphal tale, Archimedes was given the task of determining whether King Hiero's goldsmith was embezzling gold during the manufacture of a golden wreath dedicated to the gods and replacing it with another, cheaper alloy. Archimedes knew that the irregularly shaped wreath could be crushed into a cube whose volume could be calculated easily and compared with the mass; but the king did not approve of this. Baffled, Archimedes is said to have taken an immersion bath and observed from the rise of the water upon entering that he could calculate the volume of the gold wreath through the displacement of the water. Upon this discovery, he leapt from his bath and ran naked through the streets shouting, "Eureka! Eureka!" (Εύρηκα! Greek "I have found it"). As a result, the term "eureka" entered common parlance and is used today to indicate a moment of enlightenment.
The story first appeared in written form in Vitruvius' books of architecture, two centuries after it supposedly took place. Some scholars have doubted the accuracy of this tale, saying among other things that the method would have required precise measurements that would have been difficult to make at the time.
From the equation for density (ρ = m/V), mass density has units of mass divided by volume. As there are many units of mass and volume covering many different magnitudes there are a large number of units for mass density in use. The SI unit of kilogram per cubic metre (kg/m3) and the cgs unit of gram per cubic centimetre (g/cm3) are probably the most commonly used units for density. One g/cm3 is equal to one thousand kg/m3. One cubic centimetre (abbreviation cc) is equal to one millilitre. In industry, other larger or smaller units of mass and or volume are often more practical and US customary units may be used. See below for a list of some of the most common units of density.
Measurement of density
The density at all points of a homogeneous object equals its total mass divided by its total volume. The mass is normally measured with a scale or balance; the volume may be measured directly (from the geometry of the object) or by the displacement of a fluid. To determine the density of a liquid or a gas, a hydrometer, a dasymeter or a Coriolis flow meter may be used, respectively. Similarly, hydrostatic weighing uses the displacement of water due to a submerged object to determine the density of the object.
If the body is not homogeneous, then its density varies between different regions of the object. In that case the density around any given location is determined by calculating the density of a small volume around that location. In the limit of an infinitesimal volume the density of an inhomogeneous object at a point becomes: , where is an elementary volume at position . The mass of the body then can be expressed as
In practice, bulk materials such as sugar, sand, or snow contain voids. Many materials exist in nature as flakes, pellets, or granules.
Voids are regions which contain something other than the considered material. Commonly the void is air, but it could also be vacuum, liquid, solid, or a different gas or gaseous mixture.
The bulk volume of a material—inclusive of the void fraction—is often obtained by a simple measurement (e.g. with a calibrated measuring cup) or geometrically from known dimensions.
Mass divided by bulk volume determines bulk density. This is not the same thing as volumetric mass density.
To determine volumetric mass density, one must first discount the volume of the void fraction. Sometimes this can be determined by geometrical reasoning. For the close-packing of equal spheres the non-void fraction can be at most about 74%. It can also be determined empirically. Some bulk materials, however, such as sand, have a variable void fraction which depends on how the material is agitated or poured. It might be loose or compact, with more or less air space depending on handling.
In practice, the void fraction is not necessarily air, or even gaseous. In the case of sand, it could be water, which can be advantageous for measurement as the void fraction for sand saturated in water—once any air bubbles are thoroughly driven out—is potentially more consistent than dry sand measured with an air void.
In the case of non-compact materials, one must also take care in determining the mass of the material sample. If the material is under pressure (commonly ambient air pressure at the earth's surface) the determination of mass from a measured sample weight might need to account for buoyancy effects due to the density of the void constituent, depending on how the measurement was conducted. In the case of dry sand, sand is so much denser than air that the buoyancy effect is commonly neglected (less than one part in one thousand).
Mass change upon displacing one void material with another while maintaining constant volume can be used to estimate the void fraction, if the difference in density of the two voids materials is reliably known.
Changes of density
In general, density can be changed by changing either the pressure or the temperature. Increasing the pressure always increases the density of a material. Increasing the temperature generally decreases the density, but there are notable exceptions to this generalization. For example, the density of water increases between its melting point at 0 °C and 4 °C; similar behavior is observed in silicon at low temperatures.
The effect of pressure and temperature on the densities of liquids and solids is small. The compressibility for a typical liquid or solid is 10−6 bar−1 (1 bar = 0.1 MPa) and a typical thermal expansivity is 10−5 K−1. This roughly translates into needing around ten thousand times atmospheric pressure to reduce the volume of a substance by one percent. (Although the pressures needed may be around a thousand times smaller for sandy soil and some clays.) A one percent expansion of volume typically requires a temperature increase on the order of thousands of degrees Celsius.
In contrast, the density of gases is strongly affected by pressure. The density of an ideal gas is
where M is the molar mass, P is the pressure, R is the universal gas constant, and T is the absolute temperature. This means that the density of an ideal gas can be doubled by doubling the pressure, or by halving the absolute temperature.
In the case of volumic thermal expansion at constant pressure and small intervals of temperature the temperature dependence of density is :
where is the density at a reference temperature, is the thermal expansion coefficient of the material at temperatures close to .
Density of solutions
Mass (massic) concentration of each given component ρi in a solution sums to density of the solution.
provided that there is no interaction between the components.
Knowing the relation between excess volumes and activity coefficients of the components, one can determine the activity coefficients.
|Material||ρ (kg/m3)[note 1]||Notes|
|Metallic microlattice||0.9||[note 2]|
|Air||1.2||At sea level|
|Tungsten hexafluoride||12.4||One of the heaviest known gases at standard conditions|
|Liquid hydrogen||70||At approx. −255 °C|
|Ice||916.7||At temperature < 0 °C|
|Water (fresh)||1,000||At 4 °C, the temperature of its maximum density|
|Liquid oxygen||1,141||At approx. −219 °C|
|Plastics||1,175||Approx.; for polypropylene and PETE/PVC|
|Diiodomethane||3,325||Liquid at room temperature|
|Interstellar medium||×10−191||Assuming 90% H, 10% He; variable T|
|The Earth||5,515||Mean density.|
|The inner core of the Earth||13,000||Approx., as listed in Earth.|
|The core of the Sun||33,000–160,000||Approx.|
|Super-massive black hole||×1059||Density of a 4.5-million-solar-mass black hole|
Event horizon radius is 13.5 million km.
|White dwarf star||×1092.1||Approx.|
|Atomic nuclei||×10172.3||Does not depend strongly on size of nucleus|
|Stellar-mass black hole||×10181||Density of a 4-solar-mass black hole|
Event horizon radius is 12 km.
|Temp. (°C)[note 1]||Density (kg/m3)|
|T (°C)||ρ (kg/m3)|
Molar volumes of liquid and solid phase of elements
The SI unit for density is:
The litre and metric tons are not part of the SI, but are acceptable for use with it, leading to the following units:
Densities using the following metric units all have exactly the same numerical value, one thousandth of the value in (kg/m3). Liquid water has a density of about 1 kg/dm3, making any of these SI units numerically convenient to use as most solids and liquids have densities between 0.1 and 20 kg/dm3.
- kilogram per cubic decimetre (kg/dm3)
- gram per cubic centimetre (g/cm3)
- 1 g/cm3 = 1000 kg/m3
- megagram (metric ton) per cubic metre (Mg/m3)
In US customary units density can be stated in:
- Avoirdupois ounce per cubic inch (1 g/cc ≈ 0.578036672 oz/cu in)
- Avoirdupois ounce per fluid ounce (1 g/cc ≈ 1.04317556 oz/fl. oz = 1.04317556 lbs/pint)
- Avoirdupois pound per cubic inch (1 g/cc ≈ 0.036127292 lb/cu in)
- pound per cubic foot (1 g/cc ≈ 62.427961 lb/cu ft)
- pound per cubic yard (1 g/cc ≈ 1685.5549 lb/cu yd)
- pound per US liquid gallon (1 g/cc ≈ 8.34540445 lb/gal)
- pound per US bushel (1 g/cc ≈ 77.6888513 lb/bu)
- slug per cubic foot
Imperial units differing from the above (as the Imperial gallon and bushel differ from the US units) in practice are rarely used, though found in older documents. The Imperial gallon was based on the concept that an Imperial fluid ounce of water would have a mass of one Avoirdupois ounce, and indeed 1 g/cc ≈ 1.00224129 ounces per Imperial fluid ounce = 10.0224129 pounds per Imperial gallon. The density of precious metals could conceivably be based on Troy ounces and pounds, a possible cause of confusion.
- List of elements by density
- Air density
- Area density
- Bulk density
- Charge density
- Density prediction by the Girolami method
- Energy density
- Lighter than air
- Linear density
- Number density
- Orders of magnitude (density)
- Orthobaric density
- Paper density
- Specific weight
- Spice (oceanography)
- Standard temperature and pressure
- The National Aeronautic and Atmospheric Administration's Glenn Research Center. "Gas Density Glenn research Center". grc.nasa.gov. Archived from the original on April 14, 2013.
- "Density definition in Oil Gas Glossary". Oilgasglossary.com. Archived from the original on August 5, 2010. Retrieved September 14, 2010.
- Archimedes, A Gold Thief and Buoyancy Archived August 27, 2007, at the Wayback Machine. – by Larry "Harris" Taylor, Ph.D.
- Vitruvius on Architecture, Book IX, paragraphs 9–12, translated into English and in the original Latin.
- "EXHIBIT: The First Eureka Moment". Science. 305 (5688): 1219e. 2004. doi:10.1126/science.305.5688.1219e.
- Fact or Fiction?: Archimedes Coined the Term "Eureka!" in the Bath, Scientific American, December 2006.
- New carbon nanotube struructure aerographite is lightest material champ Archived October 17, 2013, at the Wayback Machine.. Phys.org (July 13, 2012). Retrieved on July 14, 2012.
- Aerographit: Leichtestes Material der Welt entwickelt – SPIEGEL ONLINE Archived October 17, 2013, at the Wayback Machine.. Spiegel.de (July 11, 2012). Retrieved on July 14, 2012.
- "Re: which is more bouyant [sic] styrofoam or cork". Madsci.org. Archived from the original on February 14, 2011. Retrieved September 14, 2010.
- Raymond Serway; John Jewett (2005), Principles of Physics: A Calculus-Based Text, Cengage Learning, p. 467, ISBN 0-534-49143-X, archived from the original on May 17, 2016
- "Wood Densities". www.engineeringtoolbox.com. Archived from the original on October 20, 2012. Retrieved October 15, 2012.
- "Density of Wood". www.simetric.co.uk. Archived from the original on October 26, 2012. Retrieved October 15, 2012.
- CRC Press Handbook of tables for Applied Engineering Science, 2nd Edition, 1976, Table 1-59
- glycerol composition at Archived February 28, 2013, at the Wayback Machine.. Physics.nist.gov. Retrieved on July 14, 2012.
- Hugh D. Young; Roger A. Freedman. University Physics with Modern Physics Archived April 30, 2016, at the Wayback Machine.. Addison-Wesley; 2012. ISBN 978-0-321-69686-1. p. 374.
- Density of the Earth, wolframalpha.com, archived from the original on October 17, 2013
- Density of Earth's core, wolframalpha.com, archived from the original on October 17, 2013
- Density of the Sun's core, wolframalpha.com, archived from the original on October 17, 2013
- Extreme Stars: White Dwarfs & Neutron Stars Archived September 25, 2007, at the Wayback Machine., Jennifer Johnson, lecture notes, Astronomy 162, Ohio State University. Accessed: May 3, 2007.
- Nuclear Size and Density Archived July 6, 2009, at the Wayback Machine., HyperPhysics, Georgia State University. Accessed: June 26, 2009.
- "Density". Encyclopædia Britannica. 8 (11th ed.). 1911.
- "Density". The New Student's Reference Work. 1914.
- Video: Density Experiment with Oil and Alcohol
- Video: Density Experiment with Whiskey and Water
- Glass Density Calculation – Calculation of the density of glass at room temperature and of glass melts at 1000 – 1400°C
- List of Elements of the Periodic Table – Sorted by Density
- Calculation of saturated liquid densities for some components
- Field density test
- On-line calculator for densities and partial molar volumes of aqueous solutions of some common electrolytes and their mixtures, at temperatures up to 323.15 K.[permanent dead link]
- Water – Density and specific weight
- Temperature dependence of the density of water – Conversions of density units
- A delicious density experiment
- Water density calculator Water density for a given salinity and temperature.
- Liquid density calculator Select a liquid from the list and calculate density as a function of temperature.
- Gas density calculator Calculate density of a gas for as a function of temperature and pressure.
- Densities of various materials.
- Determination of Density of Solid, instructions for performing classroom experiment.
- density prediction
- density prediction | <urn:uuid:5fc0e338-d9da-4637-8d98-15a5e7a002c7> | 4.28125 | 3,928 | Knowledge Article | Science & Tech. | 51.359941 | 95,599,056 |
Three ESA missions are due to send down robotic `spaceprobes` when they arrive at their alien destinations. Since these craft will be going where no one has gone before, how can scientists be sure what it will be like down there? How do you ensure that your spaceprobe is prepared for anything?
Experts take every precaution to ensure that these probes will not burn up entering an alien atmosphere, or meet a spectacular, untimely end via a crash landing on inhospitable terrain. These probes expect the worst.
For example, the Huygens probe, which is currently on its journey to Titan, Saturn`s largest moon, on-board the Cassini spacecraft, can withstand temperatures of up to 18 000°C in the shockwave in front of the heat shield. This is about three times the Sun`s surface temperature. Why? The heat generated as Huygens travels through Titan`s thick atmosphere will be immense.
Jean-Pierre Lebreton, Huygens Project Scientist, says "Things will get interesting once Cassini draws close to Saturn. We`ll get the best views of Saturn and Titan that we ever had. We`ll also observe Titan to verify that our models are correct. If we find the atmospheric density is different from what we expected, we could consider slightly changing the angle at which Huygens enters to protect it from overheating or the parachute deploying wrongly. However, late changes may bring new risks."
Monica Talevi | European Space Agency
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
03.07.2018 | Event News
17.07.2018 | Information Technology
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The article is to appear in the online issue of the Proceedings of the National Academy of Sciences the week of Nov. 5.
“The process by which plants grow and produce more plant biomass is one of the most fundamental biological processes on the planet,” said Bradley Cardinale, lead author of the paper and assistant professor of biology at the University of California, Santa Barbara.
Plant productivity regulates the ability of nature to take greenhouse gases like carbon dioxide out of the atmosphere, as well as the ability of habitats to produce oxygen, food, fiber, and biofuels, according to the authors of the study. “Therefore, species extinctions could compromise the benefits that nature provides to society,” said Cardinale.
The study summarized the results of 44 experiments from around the world that simulated plant species extinction and showed that ecosystems with fewer species produce up to 50 percent less plant biomass than those with more “natural” levels of diversity.
“Our analyses provide the most comprehensive evidence yet that natural habitats with a greater variety of plant species are more productive,” said co-author Michel Loreau of McGill University in Montreal. “This occurs partly because diverse communities are more likely to contain highly productive species. But even more important, our analyses show that diverse communities are more productive because plants are ‘complementary’ in how they use biological resources. In other words, different plant species play unique roles in the environment.”
Co-author Andy Hector, an assistant professor at the University of Zurich, explained this result with a sports analogy. “The results of our analyses suggest that plant communities operate much like a soccer team,” he said. “Teams are composed of both star players and supporting players. You probably can’t win many games if you lose your top striker because she or he is the most productive player and can dominate a game. But strikers cannot win games by themselves. They need great passes from supporting players and solid goal-tending if the team is going to be successful as a whole.”
According to the authors, plant communities are also composed of both stars and supporting players. Some plants are so productive that they dominate the productivity of natural habitats. But supporting species complement the key players and enhance the productivity of plant communities even further.
They said that species extinction is one of the most pronounced environmental changes of our time and noted that many scientists now argue that the Earth is in the middle of the sixth mass extinction in the history of life. Some estimates suggest that as much as 50 percent of all known species could be extinct by the end of this century.
Cardinale emphasized that experiments to date have probably underestimated the impact of species loss on ecosystems. “We found that as experiments were run longer, they detected increasingly strong impacts of species diversity on plant productivity,” he said. “Unfortunately, because most experiments have only been funded to run for a few years at a time, they have probably underestimated the impacts of extinction on natural habitats.”
Gail Gallessich | EurekAlert!
Upcycling of PET Bottles: New Ideas for Resource Cycles in Germany
25.06.2018 | Fraunhofer-Institut für Betriebsfestigkeit und Systemzuverlässigkeit LBF
Dry landscapes can increase disease transmission
20.06.2018 | Forschungsverbund Berlin e.V.
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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Arsenic occurs in two valence forms: trivalent (As2O3) reacting with water to give arsenious acid and forming arsenite salts, and pentavalent arsenic (As2O5) yielding arsenic acid and the corresponding arsenate salts. The arsenite compounds are more toxic to insects, mammals, and plants. Paris green (a complex between copper acetate and copper arsenite) was used in the USA since 1867. It is quite toxic to plants and animals; therefore, its use is limited to insect poison baits. Lead and calcium salts of arsenic have been the commonest arsenicals in use. Acid lead arsenate (PbHAsO4) and basic lead arsenate [Pb2(AsO4)2] are no longer used in the USA, but they still find some use in other countries for control of various beetles, weevils, leaf rollers, codling moths, and other insects damaging fruit trees. Several organoarsenicals are used as herbicides. In view of the high mammalian toxicity of lead, preparations of calcium arsenate are often preferred. Environmental pollution by lead presents a serious problem since lead is a cumulative poison.
KeywordsSodium Fluoride Fluorine Compound Arsenic Acid Calcium Arsenate Lead Arsenate
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Animal growth is closely regulated by environmental factors such as nutrition.
If the nutrition of a growing animal is limited, growth slows down and the eventual size of the animal remains smaller. Insulin-like signaling plays a key role in coordinating growth in response to dietary status in multicellular animals.
Doctoral student Kiran Hasygar and Assistant Professor Ville Hietakangas from the Department of Biosciences and Institute of Biotechnology, University of Helsinki, Finland, have now uncovered a new regulatory mechanism coordinating animal growth in response to nutrition.
By genetic screening in the fruit fly Drosophila melanogaster, Hasygar and Hietakangas identified several new genes that are involved in the activation of insulin-like signaling.
The most important finding was a new regulatory system that senses nutrient deprivation and inhibits growth. Once activated during starvation, this regulatory system prevents secretion of insulin-like peptides, which are the Drosophila counterparts of IGF and insulin.
A key component of the regulatory system is protein kinase ERK7. The physiological function of this atypical MAP kinase has previously been poorly understood, but now we are the first to have found an in vivo role for it, Assistant Professor Ville Hietakangas says.
Ville Hietakangas | 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
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
19.07.2018 | Life Sciences
19.07.2018 | Earth Sciences
19.07.2018 | Social Sciences | <urn:uuid:99471490-7e87-44d3-b181-cf61069ea988> | 3.046875 | 915 | Content Listing | Science & Tech. | 32.629742 | 95,599,080 |
Environmental managers will soon have a whole new understanding of how far critically endangered Leadbeater’s Possums travel each night and how their habitats
can best be managed.
This data will be provided by tiny GPS tracking harnesses, custom built by researchers at ANU and funded largely through the TSR Hub.
“This research is just now possible with the new transmitters, which are the best and smallest available. They’re only 7 grams in size but hold batteries, motion detection electronics and an antenna,” says Lachie McBurney, Senior Research Officer at Fenner School of Environment and Society.
“In the past we’ve used traditional UHF radio tracking collars and would walk through dark, wet and dense mountain ash forest with big radio antennae trying to work out which direction the animals were coming from.
“It was dangerous - Leadbeater's Possums live in really thick forest: 80-metre-tall trees, 30-metres in the mid story and really dense understory. All you’re really doing if you’re trying to follow an animal at night with a UHF collar is scaring it away from you.
“Now, like the GPS in your phone or car, we can record where the possums are at any given point in time. We’ll get around a week’s detailed data, recorded at ten minute intervals each night to preserve battery life.”
Understanding how far Leadbeater's Possums move will guide state government departments such as Parks Victoria, Victorian Department of Environment, Land, Water and Planning, Melbourne Water and Zoos Victoria in their forest management planning.
“This will influence policy and management on the ground in state forest and national parks, as well as timber production forest areas, where they live. We’ll know how much habitat needs to be protected to ensure the survival of each colony – if it needs to be altered or expanded from current protections.”
Trials are currently taking place with the new harnesses to test the electronics and accuracy, and the research will run at a number of sites over the following 6-18 months.
“We’ll most likely be analysing the data over the next year but as this is a critically endangered animal, this is the only place they exist anywhere in the world, we imagine the results will influence management decisions quite quickly.”
And how do you trap a Leadbeater's Possum?
“Peanut butter, oats and lots of honey. And hard work!”
Image: Leadbeater's Possum by Lachie McBurney, Fenner School of Environment and Society.
Most people know that cats kill many birds and mammals, but they also have impacts on less charismatic species.
Australian cats are killing about 650 million reptiles per year, according to new research published in the journal Wildlife Research.
You have to be pretty lucky to make a living by combining your passion and interests, and that’s exactly how Dr Daniel White feels about his current state of affairs. Dan began his career studying genes, and has since applied his science to saving species. Here he describes how.
The TSR Hub recognises that outcomes for threatened species will be improved by increasing Indigenous involvement in their management. In response to this, the Hub is guided by an Indigenous Reference Group and has a number of projects across Australia that are collaborating with Indigenous groups on threatened species research on their country.
A new contagious fungal plant disease has entered Australia, myrtle rust. It’s highly mobile, can reproduce rapidly and is infecting many species across a broad geographic range. Containment and eradication responses have so far been unsuccessful.
Australia is losing large old hollow-bearing trees in our mountain ash forests due to logging, fires and climate change. A team at the Australian National University have been investigating the importance of these trees, the implications of their loss and things we can do to ensure we have enough mountain giants for the future. | <urn:uuid:07b0ea67-bb1a-46a4-a4b1-4b9ba6ccd019> | 3.90625 | 836 | News (Org.) | Science & Tech. | 42.899823 | 95,599,088 |
Predator-prey dynamics are an important evolutionary driver of escalating predation mode and efficiency, and commensurate responses of prey [1-3]. Among these strategies, camouflage is important for visual concealment, with countershading the most universally observed [4-6]. Extant terrestrial herbivores free of significant predation pressure, due to large size or isolation, do not exhibit countershading. Modern predator-prey dynamics may not be directly applicable to those of the Mesozoic due to the dominance of very large, visually oriented theropod dinosaurs . Despite thyreophoran dinosaurs' possessing extensive dermal armor, some of the most extreme examples of anti-predator structures [8, 9], little direct evidence of predation on these and other dinosaur megaherbivores has been documented. Here we describe a new, exquisitely three-dimensionally preserved nodosaurid ankylosaur, Borealopelta markmitchelli gen. et sp. nov., from the Early Cretaceous of Alberta, which preserves integumentary structures as organic layers, including continuous fields of epidermal scales and intact horn sheaths capping the body armor. We identify melanin in the organic residues through mass spectroscopic analyses and observe lighter pigmentation of the large parascapular spines, consistent with display, and a pattern of countershading across the body. With an estimated body mass exceeding 1,300 kg, B. markmitchelli was much larger than modern terrestrial mammals that either are countershaded or experience significant predation pressure as adults. Presence of countershading suggests predation pressure strong enough to select for concealment in this megaherbivore despite possession of massive dorsal and lateral armor, illustrating a significant dichotomy between Mesozoic predator-prey dynamics and those of modern terrestrial systems.
The century-old idea that stripes make zebras cryptic to large carnivores has never been examined systematically. We evaluated this hypothesis by passing digital images of zebras through species-specific spatial and colour filters to simulate their appearance for the visual systems of zebras' primary predators and zebras themselves. We also measured stripe widths and luminance contrast to estimate the maximum distances from which lions, spotted hyaenas, and zebras can resolve stripes. We found that beyond ca. 50 m (daylight) and 30 m (twilight) zebra stripes are difficult for the estimated visual systems of large carnivores to resolve, but not humans. On moonless nights, stripes are difficult for all species to resolve beyond ca. 9 m. In open treeless habitats where zebras spend most time, zebras are as clearly identified by the lion visual system as are similar-sized ungulates, suggesting that stripes cannot confer crypsis by disrupting the zebra’s outline. Stripes confer a minor advantage over solid pelage in masking body shape in woodlands, but the effect is stronger for humans than for predators. Zebras appear to be less able than humans to resolve stripes although they are better than their chief predators. In conclusion, compared to the uniform pelage of other sympatric herbivores it appears highly unlikely that stripes are a form of anti-predator camouflage.
Although biologists routinely label animals as predators and prey, the ecological role of individuals is often far from clear. There are many examples of role reversals in predators and prey, where adult prey attack vulnerable young predators. This implies that juvenile prey that escape from predation and become adult can kill juvenile predators. We show that such an exposure of juvenile prey to adult predators results in behavioural changes later in life: after becoming adult, these prey killed juvenile predators at a faster rate than prey that had not been exposed. The attacks were specifically aimed at predators of the species to which they had been exposed. This suggests that prey recognize the species of predator to which they were exposed during their juvenile stage. Our results show that juvenile experience affects adult behaviour after a role reversal.
Camouflage, and in particular background-matching, is one of the most common anti-predator strategies observed in nature. Animals can improve their match to the colour/pattern of their surroundings through background selection, and/or by plastic colour change. Colour change can occur rapidly (a few seconds), or it may be slow, taking hours to days. Many studies have explored the cues and mechanisms behind rapid colour change, but there is a considerable lack of information about slow colour change in the context of predation: the cues that initiate it, and the range of phenotypes that are produced. Here we show that peppered moth (Biston betularia) larvae respond to colour and luminance of the twigs they rest on, and exhibit a continuous reaction norm of phenotypes. When presented with a heterogeneous environment of mixed twig colours, individual larvae specialise crypsis towards one colour rather than developing an intermediate colour. Flexible colour change in this species has likely evolved in association with wind dispersal and polyphagy, which result in caterpillars settling and feeding in a diverse range of visual environments. This is the first example of visually induced slow colour change in Lepidoptera that has been objectively quantified and measured from the visual perspective of natural predators.
Tourism can be deleterious for wildlife because it triggers behavioral changes in individuals with cascading effects on populations and communities. Among these behavioral changes, animals around humans often reduce their fearfulness and antipredator responses towards humans. A straightforward prediction is that habituation to humans associated with tourism would negatively influence reaction to predators. This could happen indirectly, where human presence decreases the number of natural predators and thus prey become less wary, or directly, where human-habituated individuals become bolder and thus more vulnerable to predation. Building on ideas from the study of traits associated with domestication and urbanization, we develop a framework to understand how behavioral changes associated with nature-based tourism can impact individual fitness, and thus the demographic trajectory of a population.
Camouflage is perhaps the most widespread defence against predators in nature and an active area of interdisciplinary research. Recent work has aimed to understand what camouflage types exist (e.g. background matching, disruptive, and distractive patterns) and their effectiveness. However, work has almost exclusively focused on the efficacy of these strategies in preventing initial detection, despite the fact that predators often encounter the same prey phenotype repeatedly, affording them opportunities to learn to find those prey more effectively. The overall value of a camouflage strategy may, therefore, reflect both its ability to prevent detection by predators and resist predator learning. We conducted four experiments with humans searching for hidden targets of different camouflage types (disruptive, distractive, and background matching of various contrast levels) over a series of touch screen trials. As with previous work, disruptive coloration was the most successful method of concealment overall, especially with relatively high contrast patterns, whereas potentially distractive markings were either neutral or costly. However, high contrast patterns incurred faster decreases in detection times over trials compared to other stimuli. In addition, potentially distractive markings were sometimes learnt more slowly than background matching markings, despite being found more readily overall. Finally, learning effects were highly dependent upon the experimental paradigm, including the number of prey types seen and whether subjects encountered targets simultaneously or sequentially. Our results show that the survival advantage of camouflage strategies reflects both their ability to avoid initial detection (sensory mechanisms) and predator learning (perceptual mechanisms).
The behavioural rhythms of organisms are thought to be under strong selection, influenced by the rhythmicity of the environment. Such behavioural rhythms are well studied in isolated individuals under laboratory conditions, but free-living individuals have to temporally synchronize their activities with those of others, including potential mates, competitors, prey and predators. Individuals can temporally segregate their daily activities (for example, prey avoiding predators, subordinates avoiding dominants) or synchronize their activities (for example, group foraging, communal defence, pairs reproducing or caring for offspring). The behavioural rhythms that emerge from such social synchronization and the underlying evolutionary and ecological drivers that shape them remain poorly understood. Here we investigate these rhythms in the context of biparental care, a particularly sensitive phase of social synchronization where pair members potentially compromise their individual rhythms. Using data from 729 nests of 91 populations of 32 biparentally incubating shorebird species, where parents synchronize to achieve continuous coverage of developing eggs, we report remarkable within- and between-species diversity in incubation rhythms. Between species, the median length of one parent’s incubation bout varied from 1-19 h, whereas period length-the time in which a parent’s probability to incubate cycles once between its highest and lowest value-varied from 6-43 h. The length of incubation bouts was unrelated to variables reflecting energetic demands, but species relying on crypsis (the ability to avoid detection by other animals) had longer incubation bouts than those that are readily visible or who actively protect their nest against predators. Rhythms entrainable to the 24-h light-dark cycle were less prevalent at high latitudes and absent in 18 species. Our results indicate that even under similar environmental conditions and despite 24-h environmental cues, social synchronization can generate far more diverse behavioural rhythms than expected from studies of individuals in captivity. The risk of predation, not the risk of starvation, may be a key factor underlying the diversity in these rhythms.
Perceptual abilities of animals, like echolocating bats, are difficult to study because they challenge our understanding of non-visual senses. We used novel acoustic tomography to convert echoes into visual representations and compare these cues to traditional echo measurements. We provide a new hypothesis for the echo-acoustic basis of prey detection on surfaces. We propose that bats perceive a change in depth profile and an ‘acoustic shadow’ cast by prey. The shadow is more salient than prey echoes and particularly strong on smooth surfaces. This may explain why bats look for prey on flat surfaces like leaves using scanning behaviour. We propose that rather than forming search images for prey, whose characteristics are unpredictable, predators may look for disruptions to the resting surface (acoustic shadows). The fact that the acoustic shadow is much fainter on rougher resting surfaces provides the first empirical evidence for ‘acoustic camouflage’ as an anti-predator defence mechanism.
Invasive species cause catastrophic alterations to communities worldwide by changing the trophic balance within ecosystems. Ever since their introduction in the mid 1980’s common red lionfish, Pterois volitans, are having dramatic impacts on the Caribbean ecosystem by displacing native species and disrupting food webs. Introduced lionfish capture prey at extraordinary rates, altering the composition of benthic communities. Here we demonstrate that the extraordinary success of the introduced lionfish lies in its capacity to circumvent prey risk assessment abilities as it is virtually undetectable by prey species in its native range. While experienced prey damselfish, Chromis viridis, respond with typical antipredator behaviours when exposed to a common predatory rock cod (Cephalopholis microprion) they fail to visibly react to either the scent or visual presentation of the red lionfish, and responded only to the scent (not the visual cue) of a lionfish of a different genus, Dendrochirus zebra. Experienced prey also had much higher survival when exposed to the two non-invasive predators compared to P. volitans. The cryptic nature of the red lionfish has enabled it to be destructive as a predator and a highly successful invasive species.
- Proceedings. Biological sciences / The Royal Society
- Published over 2 years ago
Ambush foragers use a hunting strategy that places them at risk of predation by both visual and olfaction-oriented predators. Resulting selective pressures have driven the evolution of impressive visual crypsis in many ambushing species, and may have led to the development of chemical crypsis. However, unlike for visual crypsis, few studies have attempted to demonstrate chemical crypsis. Field observations of puff adders (Bitis arietans) going undetected by several scent-orientated predator and prey species led us to investigate chemical crypsis in this ambushing species. We trained dogs (Canis familiaris) and meerkats (Suricata suricatta) to test whether a canid and a herpestid predator could detect B. arietans using olfaction. We also tested for chemical crypsis in five species of active foraging snakes, predicted to be easily detectable. Dogs and meerkats unambiguously indicated active foraging species, but failed to correctly indicate puff adder, confirming that B. arietans employs chemical crypsis. This is the first demonstration of chemical crypsis anti-predatory behaviour, though the phenomenon may be widespread among ambushers, especially those that experience high mortality rates owing to predation. Our study provides additional evidence for the existence of an ongoing chemically mediated arms race between predator and prey species. | <urn:uuid:940ceeaf-7202-454b-be35-61457aec7fd5> | 2.875 | 2,685 | Academic Writing | Science & Tech. | 13.060414 | 95,599,119 |
Researcher finds effects of earlier breeding and weather
Scientists have found amphibians worldwide are breeding earlier due to climate change, but how that affects species is just now being answered.
After warmer winters, wood frogs breed earlier and produce fewer eggs, a Case Western Reserve University researcher has found.
Michael F. Benard, the George B. Mayer Chair in Urban and Environmental Studies and assistant professor of biology, also found that frogs produce more eggs during winters with more rain and snow.
Benard's study, published today in the journal Global Change Biology, is among the first in a natural habitat to measure the consequences of one of the major effects of climate change: warmer temperatures that lead to earlier breeding in amphibians and other animals.
Benard also found that when wood frogs breed early in the year, their offspring have delayed development but still metamorphose earlier in the year. He identified the broad patterns by examining and tracking important life events of more than 50,000 juvenile and hundreds of adult wood frogs over seven years and comparing the data to winter weather records.
"There have been lab studies on the effects of warming on frog breeding, but what we see in the lab is not exactly what we're seeing in the field," Benard said.
Wood frogs, found from Alabama to Alaska, literally must thaw out from winter. Biologists believe they breed after temperatures and precipitation reach a certain threshold over a number of days. But the exact formula is unknown. During breeding, each female lays all of her eggs in one mass, called a clutch, which makes egg-counting possible.
After analyzing data collected from 2006 to 2012, Benard found that for every degree Celsius increase in average daily maximum winter temperature:
"The decrease in eggs per clutch is likely due to increased energy consumption by the females during warmer winters," Benard explained.
The frogs produce a kind of anti-freeze that prevents their cells from freezing. But the fluid between cells freezes, and the animals' heartbeat and breathing halts in subzero temperatures. If frogs stay frozen longer, their metabolism is greatly reduced.
Opposite to warming, more rain and snow appear to have a positive effect on egg production. For every 2.5-centimeter increase in total precipitation, the number of eggs per clutch increased 2.3 percent, or 16.5 eggs. The reason is uncertain, but with climate change expected to increase rainfall in some regions, the effect may help counter potential losses associated with warming.
Benard found no effect of breeding date on tadpole survival or their size at metamorphosis. But earlier breeding was associated with delayed tadpole development due to a counter-intuitive effect of warmer winters on the temperatures that tadpoles experience. It turns out that although earlier breeding is triggered by warmer winters, when breeding occurs earlier, the pond water in which tadpoles develop is colder than if breeding took place in later spring. Colder water likely slowed the advancement from egg to metamorphosis.
Although tadpole development was slowed, for every two days earlier that breeding took place, metamorphosis was a day earlier.
"Earlier metamorphosis potentially increases survivorship," Benard said. "Other studies have found that, after a longer summer growth period, amphibians were larger come winter and had better chances of surviving the cold, predators and disease.
"I'm not sure that's the case here," he said. "That will take more study."
Benard was a fellow in the University of Michigan's Society of Fellows when he began the study at six ponds in the university's E.S. George Reserve, a 1,300-acre research station in southeastern Michigan. Temperatures were recorded by a nearby weather station.
The University of Michigan, the Michigan Society of Fellows and Case Western Reserve provided support and funding for the research. Benard is now continuing the study in Northeast Ohio.
Kevin Mayhood | Eurek Alert!
Barium ruthenate: A high-yield, easy-to-handle perovskite catalyst for the oxidation of sulfides
16.07.2018 | Tokyo Institute of Technology
The secret sulfate code that lets the bad Tau in
16.07.2018 | American Society for Biochemistry and Molecular Biology
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
16.07.2018 | Physics and Astronomy
16.07.2018 | Life Sciences
16.07.2018 | Earth Sciences | <urn:uuid:49d8009c-56cf-490d-bd7b-2447f029a5f3> | 3.359375 | 1,451 | Content Listing | Science & Tech. | 42.010804 | 95,599,151 |
Which is larger cos(sin x) or sin(cos x) ? Does this depend on x ?
Can you explain what is happening and account for the values being displayed?
The length AM can be calculated using trigonometry in two different ways. Create this pair of equivalent calculations for different peg boards, notice a general result, and account for it.
An environment that simulates a protractor carrying a right- angled triangle of unit hypotenuse.
A dot starts at the point (1,0) and turns anticlockwise. Can you estimate the height of the dot after it has turned through 45 degrees? Can you calculate its height?
There are many different methods to solve this geometrical problem - how many can you find?
Three points A, B and C lie in this order on a line, and P is any point in the plane. Use the Cosine Rule to prove the following statement.
Three squares are drawn on the sides of a triangle ABC. Their areas are respectively 18 000, 20 000 and 26 000 square centimetres. If the outer vertices of the squares are joined, three more. . . .
The sine of an angle is equal to the cosine of its complement. Can you explain why and does this rule extend beyond angles of 90 degrees?
What are the shortest distances between the centres of opposite faces of a regular solid dodecahedron on the surface and through the middle of the dodecahedron?
Prove Pythagoras' Theorem for right-angled spherical triangles.
An observer is on top of a lighthouse. How far from the foot of the lighthouse is the horizon that the observer can see? | <urn:uuid:89e1a887-cb0b-48a4-b171-3bd5b86e5f74> | 3.359375 | 346 | Q&A Forum | Science & Tech. | 64.497102 | 95,599,160 |
Palythoa (Palythoa sp.)
Family: Zoanthidae (Colonial Anemones)
Habitat: Shallow high flow and mix areas of reefs.
Light: High Water Flow: High Space: 1+ gal.
Reef Safe: Yes Care Level: Easy Temperament: Aggressive
Diet: Zoanthids have zooxanthellae but must also feed on plankton. They also likely directly absorb nutrients from the water.
Natural History: The Palythoa are a colonial genus that cover large tracts of reef. They incoroporate sediments from the substrate and ocean around them and may accumulate almost half of their body weight in collected materials in their mesoglea. The polyps are round flat discs with short tentacles around the rim. The polyps can actually produce aragonite crystals, but only in small amounts. They are most common on the shoreward side of reef crests. Common colors include cream, yellow, and brown. The Palythoa can dominate a reef by growing over their competitors.
Husbandry: Palythoa prefer moderate to strong water flow and bright light. Palythoa are very competitive and will kill most other species of corals that are housed too closely. They produce a very potent neurotoxin, secreted in their mucus, that can be deadly to humans. Care should be employed in handling them! They are aggressive through growth and can cover other corals.
AKA: Sea Mat, Button Polyps
In Stock: 08/09/14, Yes
|© SeaScape Studio|
|Home > Library > Cnidaria > Colonial Anemones > Zoanthidae > Palythoa <> [References]||Back| | <urn:uuid:2f5c5768-3fe9-44f0-a4d5-05408c8f83fe> | 3 | 363 | Knowledge Article | Science & Tech. | 41.36094 | 95,599,171 |
NASA's Hubble Space Telescope has photographed an unusual structure 100,000 light years long, which resembles a corkscrew-shaped string of pearls and winds around the cores of two colliding galaxies.
The unique structure of the star spiral may yield new insights into the formation of stellar superclusters that result from merging galaxies and gas dynamics in this rarely seen process.
"We were surprised to find this stunning morphology. We've long known that the 'beads on a string' phenomenon is seen in the arms of spiral galaxies and in tidal bridges between interacting galaxies. However, this particular supercluster arrangement has never been seen before in giant merging elliptical galaxies," said Grant Tremblay of the European Southern Observatory in Garching, Germany.
Young, blue super star clusters are evenly spaced along the chain through the galaxies at separations of 3,000 light-years. The pair of elliptical galaxies is embedded deep inside the dense galaxy cluster known as SDSS J1531+3414. The cluster's powerful gravity warps the images of background galaxies into blue streaks and arcs that give the illusion of being inside the cluster, an effect known as gravitational lensing.
Observing astronomers first hypothesized that the "string of pearls" was actually a lensed image from one of these background galaxies, but their recent follow-up observations with the Nordic Optical Telescope in Santa Cruz de Tenerife, Spain, ruled out this hypothesis.
The galaxy cluster is part of a Hubble program to observe 23 massive clusters that create powerful gravitational lensing effects on the sky. The clusters were first cataloged in the Sloan Digital Sky Survey (SDSS), a project to create the most detailed three-dimensional maps ever made of the universe.
Tremblay's team discovered the bizarre string of stellar superclusters by chance, while reviewing images as they came in from Hubble. Researchers were stunned by what they saw in SDSS J1531+3414, and the unique nature of the source spurred the team to do follow-up observations with both ground and space-based telescopes.
The underlying physical processes that give rise to the "string of pearls" structure are related to the Jeans instability, a physics phenomenon that occurs when the internal pressure of an interstellar gas cloud is not strong enough to prevent gravitational collapse of a region filled with matter, resulting in star formation. This process is analogous to that which causes a column of water falling from a rain cloud to disrupt, and rain to fall in drops rather than in continuous streams.
Scientists currently are working on a better understanding of the star chain's origin. One possibility is that the cold molecular gas fueling the burst of star formation may have been native to the two merging galaxies. Another possibility is a so-called "cooling flow" scenario, where gas cools from the ultra-hot atmosphere of plasma that surrounds the galaxies, forming pools of cold molecular gas that starts to form stars. The third possibility is that the cold gas fueling the chain of star formation originates from a high-temperature shock wave created when the two giant elliptical galaxies crash together. This collision compresses the gas and creates a sheet of dense cooling plasma.
"Whatever the origin for this star-forming gas is, the result is awesome. It's very exciting. You can't find a mundane explanation for this," Tremblay said.
The Hubble Space Telescope is a project of international cooperation between NASA and the European Space Agency. NASA's Goddard Space Flight Center in Greenbelt, Maryland, manages the telescope. The Space Telescope Science Institute (STScI) in Baltimore conducts Hubble science operations. STScI is operated for NASA by the Association of Universities for Research in Astronomy, Inc., in Washington.
For images and more information about Hubble, visit:
To learn more about gravitational lensing, visit:
Ray Villard | Eurek Alert!
What happens when we heat the atomic lattice of a magnet all of a sudden?
18.07.2018 | Forschungsverbund Berlin
Subaru Telescope helps pinpoint origin of ultra-high energy neutrino
16.07.2018 | National Institutes of Natural Sciences
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
18.07.2018 | Life Sciences
18.07.2018 | Materials Sciences
18.07.2018 | Health and Medicine | <urn:uuid:c0d812d1-2450-4b66-969f-da3525796feb> | 4.15625 | 1,430 | Content Listing | Science & Tech. | 40.348507 | 95,599,178 |
Six years of aerosol size distribution measurements between 20 and 600nm diameters and total aerosol concentration above 10nmfrom March 2008 to February 2014 at the high-alpine site Jungfraujoch are presented. The size distribution was found to be typically bimodal with mode diameters and widths relatively stable throughout the year and the observation period. New particle formation was observed on 14.5%of all days without a seasonal preference. Particles typically grew only into the Aitkenmode and did not reach cloud condensation nucleus (CCN) sizes on the time scale of several days. Growth of preexisting particles in the Aitkenmode, on average, contributed very few CCN. We concluded that the dominant fraction of CCN at Jungfraujoch originated in the boundary layer. A number of approaches were used to distinguish free tropospheric (FT) conditions and episodes with planetary boundary layer (PBL) influence. In the absence of PBL injections, the concentration of particles larger than 90nm (N90, roughly corresponding to the CCN concentration) reached a value ~40cm?3 while PBL influence caused N90 concentrations of several hundred or even 1000cm?3. Comparing three criteria for free tropospheric conditions, we found FT prevalence for 39% of the timewith over 60%during winter and below20%during summer. It is noteworthy that a simple criterion based on standard trace gas measurements appeared to outperform alternative approaches.
Mendeley saves you time finding and organizing research
Choose a citation style from the tabs below | <urn:uuid:4ec72611-73ee-41b5-b853-8e3f31dd00d9> | 2.5625 | 323 | Academic Writing | Science & Tech. | 34.264778 | 95,599,179 |
SCIENTISTS have discovered a new species of fish capable of withstanding crushing five-mile depths in the ocean.
The Mariana snailfish was found thriving 8,178 metres below the ocean surface, deeper than any other fish.
Named after its home, the Mariana Trench in the western Pacific Ocean, the small transparent sea creature has adapted to survive under enormous pressure at the deepest spot on Earth.
The find debunks Sir David Attenborough’s statement in the new Blue Planet II series, in which he claims the so-called etheral snailfish is “the deepest living fish ever discovered”.
Dr Thomas Linley, a leading scientist responsible for the discovery, said Mariana snailfish have been recorded swimming even deeper.
At 8,200 metres down, the snailfish could be living at the maximum depth possible for any fish to survive at.
“Our understanding of how fish operate means that 8,200 metres is the theoretical limit,” the Newcastle University academic said.
The translucent, scaleless fish survives due to a chemical in it’s body called trimethylamine N-oxide, or TMAO. It allows the molecules in bodies to withstand the crushing ocean pressure of the deep blue.
At such depths, the pressure is equivalent of “50 jumbo jets stacked on top of one another”, according to Blue Planet II. Others have said it would feel like an elephant standing on your thumb.
The deeper a fish is found in the ocean, the more TMAO is has in its body, the scientists revealed.
“At about 8,200 metres it gets so concentrated that their internal environment would be more concentrated that seawater, and it would be very difficult then for the animals to survive,” said Dr Linley.
MOST READ IN THE NEWS
“They would need a total reworking of how fish work,” he said.
Although the fish sound tough, Marine biologist at the university of Washington Dr Mackenzie Gerringer said the creatures are very fragile with paper thin skin.
“They don’t look very robust or strong for living in such an extreme environment, but they are extremely successful,” said Dr Mackenzie Gerringer, a marine biologist at the University of Washington.
We pay for your stories! Do you have a story for The Sun Online news team? Email us at firstname.lastname@example.org or call 0207 782 4368 . We pay for videos too. Click here to upload yours. | <urn:uuid:49ca5470-77b5-4bf6-a36f-fcfadf9df466> | 3.5625 | 532 | Truncated | Science & Tech. | 52.797083 | 95,599,183 |
Theories of Covalent Bonding. Valence-Shell Electron-Pair Repulsion (VSEPR) Theory Hybridization and Localized Electron Model Molecular Orbital Model Bonding in Homonuclear Diatomic Molecules Bonding in heteronuclear Diatomic Molecules Combining the Localized and Molecular Orbital Model.
s -bond: orbitals overlap along the internuclear axis
p-bond: side-to-side overlap of orbitals perpendicular to the internuclear axis
HConsider bonding in CH4
1. Draw the Lewis structure(s)
2. Determine the arrangement of electron pairs (VSEPR model).
3. Specify the necessary hybrid orbitals.
Draw the Lewis structure for PCl5.
90o and 120o
Draw the Lewis structure for XeF4.
90o and 180o
Draw the Lewis structure for HCN.
Which hybrid orbitals are used?
Determine the bond angle and expected hybridization of the central atom for each of the following molecules:
NH3 SO2 KrF2 CO2 ICl5
NH3 – 109.5o, sp3
SO2 – 120o, sp2
KrF2 – 90o, 120o, dsp3
CO2 – 180o, sp
ICl5 – 90o, 180o, d2sp3
How many σ bonds are there in the commercial insecticide, “Sevin,” shown below? How many π bonds?
There are 27 σ bonds.
There are 6 π bonds.
FPractice with Hybrid Orbitals
Give the hybridization and predict the geometry of the central atom in the ion IF2+.
There are 4 effective electron pairs around the central atom making it sp3hybridized.
The VSEPR structure has a tetrahedral basis but since it has two bonding pairs, it will take on a bent shape with a bond angle smaller than 109.5°.
Determine the number of electrons in the molecule.
Fill the energy level diagram from lowest to highest energy.
Fill each orbital with a pair of electrons and with opposite spins.
σ1sMO energy-level diagram for first period elements
2 b.e. - 2 a.e.
1 b.e. - 0 a.e.
2Exercises on Molecular Orbitals
Use MO theory to describe the bonding and stability of
H22- has 4 electrons.
H2+ has 1 electron.
H2+ may be formed, but it would not be much more stable than two separate hydrogens.
H22- ion will not be formed.
Fill degenerate orbitals p2pseparately, then pairwise with electrons having opposite spins.
Molecular orbital diagram shows that B2 molecule is paramagnetic.
BO in B2 = ½ (4 – 2) = 1
σ2sMO Energy-level Diagram for B2
Bond order in C2
= ½ (6 – 2) = 2
σ2sMO Energy-level Diagram for C2
Donald W. Clegg
σ-bonds can be regarded as localized, while
π-bonding is best described as delocalized.
there are always σ-bonds between all bound atoms in a given resonance structure.
the π-bonds may appear in different locations in various resonance structures. Electrons involved in p-bonds are said to be delocalized. | <urn:uuid:e2d5f4e6-56cc-488a-9c9d-4bd339e3eaff> | 3.21875 | 740 | Tutorial | Science & Tech. | 57.750814 | 95,599,196 |
The active laser medium (also called gain medium or lasing medium) is the source of optical gain within a laser. The gain results from the stimulated emission of electronic or molecular transitions to a lower energy state from a higher energy state
previously populated by a pump source.
Examples of active laser media include:
- Certain crystals, typically doped with rare-earth ions (e.g. neodymium, ytterbium, or erbium) or transition metal ions (titanium or chromium); most often yttrium aluminium garnet (Y3Al5O12), yttrium orthovanadate (YVO4), or sapphire (Al2O3); and not often Caesium cadmium bromide (CsCdBr3)
- Glasses, e.g. silicate or phosphate glasses, doped with laser-active ions;
- Gases, e.g. mixtures of helium and neon (HeNe), nitrogen, argon, carbon monoxide, carbon dioxide, or metal vapors;
- Semiconductors, e.g. gallium arsenide (GaAs), indium gallium arsenide (InGaAs), or gallium nitride (GaN).
- Liquids, in the form of dye solutions as used in dye lasers.
In order to fire a laser, the active gain medium must be in a nonthermal energy distribution known as a population inversion. The preparation of this state requires an external energy source and is known as laser pumping. Pumping may be achieved with electrical currents (e.g. semiconductors, or gases via high-voltage discharges) or with light, generated by discharge lamps or by other lasers (semiconductor lasers). More exotic gain media can be pumped by chemical reactions, nuclear fission, or with high-energy electron beams.
Example of a model of gain medium
Fig.1. Simplified scheme of levels a gain medium
A universal model valid for all laser types does not exist.
The simplest model includes two systems of sub-levels: upper and lower. Within each sub-level system, the fast transitions ensure that thermal equilibrium is reached quickly, leading to the Maxwell-Boltzmann statistics of excitations among sub-levels in each system (fig.1). The upper level is assumed to be metastable. Also, gain and refractive index are assumed independent of a particular way of excitation.
For good performance of the gain medium, the separation between sub-levels should be larger than working temperature; then, at pump frequency , the absorption dominates.
In the case of amplification of optical signals, the lasing frequency is called signal frequency. However, the same term is used even in the laser oscillators, when amplified radiation is used to transfer energy rather than information. The model below seems to work well for most optically-pumped solid-state lasers.
The simple medium can be characterized with effective cross-sections of absorption and emission at frequencies and .
- Have be concentration of active centers in the solid-state lasers.
- Have be concentration of active centers in the ground state.
- Have be concentration of excited centers.
- Have .
The relative concentrations can be defined as and .
The rate of transitions of an active center from ground state to the excited state can be expressed with and
The rate of transitions back to the ground state can be expressed with ,
where and are effective cross-sections of absorption at the frequencies of the signal and the pump.
and are the same for stimulated emission;
is rate of the spontaneous decay of the upper level.
Then, the kinetic equation for relative populations can be written as follows:
However, these equations keep .
The absorption at the pump frequency and the gain at the signal frequency can be written
In many cases the gain medium works in a continuous-wave or quasi-continuous regime, causing the time derivatives of populations to be negligible.
The steady-state solution can be written:
The dynamic saturation intensities can be defined:
The absorption at strong signal:
The gain at strong pump:
is determinant of cross-section.
Gain never exceeds value , and absorption never exceeds value .
At given intensities , of pump and signal, the gain and absorption
can be expressed as follows:
The following identities take place:
The state of gain medium can be characterized with a single parameter, such as population of the upper level, gain or absorption.
Efficiency of the gain medium
The efficiency of a gain medium can be defined as
Within the same model, the efficiency can be expressed as follows:
For the efficient operation both intensities, pump and signal should exceed their saturation intensities;
, and .
The estimates above are valid for a medium uniformly filled with pump and signal light. Spatial hole burning may slightly reduce the efficiency because some regions are pumped well, but the pump is not efficiently withdrawn by the signal in the nodes of the interference of counter-propagating waves.
References and notes
- ^ Hecht, Jeff. The Laser Guidebook: Second Edition. McGraw-Hill, 1992. (Chapter 22)
- ^ Hecht, Chapter 22
- ^ Hecht, Chapters 7-15
- ^ Hecht, Chapters 18-21
- ^ F. J. Duarte and L. W. Hillman (Eds.), Dye Laser Principles (Academic, New York, 1990).
- ^ F. P. Schäfer (Ed.), Dye Lasers, 2nd Edition (Springer-Verlag, Berlin, 1990).
- ^ Encyclopedia of laser physics and technology
A.E.Siegman (1986). Lasers. University Science Books. ISBN 0-935702-11-3.
- ^ D.Kouznetsov; J.F.Bisson; K.Takaichi; K.Ueda (2005). "Single-mode solid-state laser with short wide unstable cavity". JOSA B. 22 (8): 1605-1619. Bibcode:2005JOSAB..22.1605K. doi:10.1364/JOSAB.22.001605.
- A.saharn Lasing action
- Physics Encyclopedia online [in Russian]
- Gain media Encyclopedia of Laser Physics and Technology | <urn:uuid:412ec254-742a-4e78-89fc-e21adf38ed9f> | 3.265625 | 1,335 | Knowledge Article | Science & Tech. | 46.175156 | 95,599,204 |
Scientists have developed a new way of studying the atmospheres of exoplanets by using Saturn's smog-enshrouded moon, Titan. The new technique shows the significance hazy skies could have on our ability to learn about these alien worlds orbiting distant stars.
New images of Saturn's skies amidst the aurora light show support the theory that Saturn's manetotail is in the middle of a violent collapse, according to a recent observational report.
A planet parade, consisting of four of the five planets visible to the naked eye, will be in full view this month - a sight you do not want to miss.
A strange radial phenomenon that cuts across the width of Saturn's rings is visible once more, prompting scientists to wonder about its cause.
Years of research by the University of Basque Country Planetary Sciences Group have revealed intriguing clues about the planet's seasonal weather patterns and rotational period, according to a release from the school.
Come July 19, one of the most heralded Cassini space craft events of the year will take place, according to researchers at NASA's Jet Propulsion Laboratory, when the planet and its famous rings will be backlit by the Sun.
In an exciting revelation, scientists say they now understand the nature of the giant storms found on Saturn.
For years scientists have been trying to discover Saturn’s secret to looking so young. However, scientists from the University of Exeter and Ecole Normale Superieure de Lyon believe they have discovered the planet's secrete - it can't help itself.
Stargazers this Saturday and Sunday night will be rewarded with the best view of Saturn to occur all year.
The seasons are changing and not just on Earth - scientists at NASA are reporting signs that Titan, Saturn's largest moon, is currently in flux and it may have a lot to say about our own planet's changing climate.
NASA's Cassini spacecraft has released a spectacular backlit view of the planet Saturn and its rings.
NASA's Cassini spacecraft has spotted a long river valley on Saturn's moon Titan, that stretches more than 200 miles from its "headwaters" to a large sea.
Scientists have found a Pac-Man-shaped feature on Saturn's Tethys, similar to the one discovered on the planet's other moon Mimas in 2010.
European Space Agency’s Huygens probe bounced, slid and wobbled in ten seconds after landing on Saturn’s Titan moon, suggests a new analysis. | <urn:uuid:aabde8bf-e1f4-4fbf-a522-7789ad81537e> | 3.21875 | 512 | Content Listing | Science & Tech. | 44.271875 | 95,599,212 |
Long-distance space travel presents a number of challenges, including how to transport sufficient quantities of oxygen and fuel.
Hundreds of reports were made about Snapchat issues Wednesday.
Aerial photos taken on Tuesday show giant waves beating against a seashore wall in Wenling City, east of Zhejiang Province, as the storm came near.
The vermin are starving complex ecosystems of a vital but surprising ingredient: bird droppings.
“A rarely seen horror.”
New findings suggest that modern humans evolved in populations that were scattered across the African continent.
Ross 128 b is located "just" 11 light-years from Earth.
The country’s most endangered marine mammals are now facing a tiny but deadly threat to their existence.
Users can answer the questions in Instagram as many times as they want.
“There are now hundreds of individual variations throughout the genome that are roughly associated with educational outcomes between people.”
If successful, the probe will be the first privately funded unmanned spacecraft to land on the moon.
Noise pollution can disrupt the ecosystem's natural balance.
The trip was just a hair longer than an average Boston Red Sox–New York Yankees game.
Rising sea temperatures threaten the world's remaining coral, but a scientist says she knows a temporary fix.
The new findings shed light on the evolution of life on Earth.
“It’s a heavy cost for patients, their families, and society itself.”
One of the world’s most dangerous pests, this mosquito species infects millions with disease around the world each year.
The dinosaur stood over 14 feet tall and weighed up to 10 tons.
The incredible discovery will help astronomers unlock the secrets of the universe's very first galaxies.
The Russian government previously accused British intelligence officials of carrying out the Skripal poisoning as a way to stir up anti-Moscow sentiment.
Calls to animal poison control centers from worried pet owners have surged.
Astronauts likely would not have survived the nearly three-year journey on existing spacecraft, a former astronaut said.
“Food waste on a hungry planet is outrageous.”
We've come a long way since Grey Poupon Dijon mustard.
More than three dozen wildfires have broken out across the western United States, fanned by scorching heat, winds and low humidity in a particularly intense fire season.
Low gravity, surprising surfaces and chunky suits make a recipe for tumbling.
Rescuers in Japan are digging through mud and rubble, racing to find survivors after torrential rain unleashed floods and landslides that killed at least 112 people, with around 78 still missing.
You'll be able to catch the dazzling displays with the naked eye.
It’s a 90-pound robot that resembles the frame of a Rottweiler.
Animal-human encounters have risen significantly due to shared habitats and increased conservation. | <urn:uuid:a4a32a1e-2df9-4e62-85dd-26aa87aeff89> | 2.84375 | 601 | Content Listing | Science & Tech. | 46.089389 | 95,599,236 |
Defines the AdjustRightIndent Class.When the object is serialized out as xml, its qualified name is w:adjustRightInd.
Assembly: DocumentFormat.OpenXml (in DocumentFormat.OpenXml.dll)
'Declaration Public Class AdjustRightIndent _ Inherits OnOffType 'Usage Dim instance As AdjustRightIndent
public class AdjustRightIndent : OnOffType
[ISO/IEC 29500-1 1st Edition]
126.96.36.199 adjustRightInd (Automatically Adjust Right Indent When Using Document Grid)
This element specifies whether the right indent shall be automatically adjusted for the given paragraph when a document grid has been defined for the current section using the docGrid element (§17.6.5), modifying of the current right indent used on this paragraph.
[Note: This setting is used in order to ensure that the line breaking for that paragraph is not determined by the width of the final character on the line. end note]
If this element is omitted on a given paragraph, its value is determined by the setting previously set at any level of the style hierarchy (i.e. that previous setting remains unchanged). If this setting is never specified in the style hierarchy, its value is assumed to be true.
[Example: Consider a paragraph in which the right indent on the current paragraph should not be automatically determined based on the character pitch set in the document grid. This setting would be specified using the following WordprocessingML:
<w:p> <w:pPr> … <w:adjustRightInd w:val="false" /> </w:pPr> … </w:p>
By explicitly setting the val to false, this paragraph uses its specified right indent settings regardless of the presence of the document grid for the parent section. end example]
pPr (§188.8.131.52); pPr (§184.108.40.206); pPr (§220.127.116.11); pPr (§18.104.22.168); pPr (§17.9.23); pPr (§22.214.171.124)
This element’s content model is defined by the common boolean property definition in §17.17.4.
© ISO/IEC29500: 2008.
Any public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe. | <urn:uuid:7f993054-1ca9-477a-8a45-c84cd36832d9> | 3.03125 | 517 | Documentation | Software Dev. | 65.959618 | 95,599,246 |
Wave723 shares a report from IEEE Spectrum: Researchers at the U.S. Energy Department’s Pacific Northwest National Laboratory (PNNL) and LCW Supercritical Technologies made use of readily available acrylic fibers to pull five grams of yellowcake — a powdered form of uranium used to produce fuel for nuclear power reactors — from seawater. The milestone, announced in mid-June, follows seven years of work and a roughly US $25 million investment by the federal energy agency. Another $1.15 million is being channeled to LCW as it attempts to scale up the technique for commercial use. The effort builds on work by Japanese researchers in the late 1990s and was prompted by interest in finding alternative sources of uranium for a future time when terrestrial sources are depleted. “[U]ranium in seawater shows up in concentrations of around 3.3 parts per billion,” the report notes. “With a total volume estimated at more than 4 billion tons, there is around 500 times more uranium in seawater than in land-based sources.”
of this story at Slashdot. | <urn:uuid:338456ed-5a75-4d97-8537-f2cfc76c1279> | 3.03125 | 227 | Truncated | Science & Tech. | 45.175273 | 95,599,263 |
Like any density, charge density can depend on position, but charge and thus charge density can be negative. It should not be confused with the charge carrier density, the number of charge carriers (e.g. electrons, ions) in a material per unit volume, not including the actual charge on the carriers
In chemistry, it can refer to the charge distribution over the volume of a particle; such as a molecule, atom or ion. Therefore, a lithiumcation will carry a higher charge density than a sodium cation due to the lithium cation's having a smaller ionic radius, even though sodium has more protons (11) than lithium (3).
Following are the definitions for continuous charge distributions. | <urn:uuid:10f08932-85d9-4698-a814-52ddead51208> | 3.515625 | 143 | Knowledge Article | Science & Tech. | 39.514746 | 95,599,267 |
Lecture Kathrin Muller
|07 maart 2011||FWN-Building 5114.0004, Nijenborgh 4, 9747 AG, Groningen|
|Speaker:||Dr. Kathrin Muller|
|Affiliation:||Brookhaven National Laboratory, Upton, NY, USA|
|Title:||A surface science approach to to alternative CO2 capture and utilization routes|
|Date:||Mon Mar 7, 2011|
|Host:||Dr. Meike Stöhr|
|Telephone:||+31 50 363 4438|
Fossil-fuel power plants are among the largest CO2 emission sources accounting for approximately one-third of the anthropogenic CO2 emission. Due to increasing energy demands and slow deployment of clean energy alternatives, a practical near term route to CO2 mitigation is through CO2 capture and utilization. Today, CO2 capture from power plants is typically done using aqueous solutions of monoethanolamine (MEA). Disadvantages of this method include: high costs for regenerating the MEA solution after CO2 capture, solution degradation by flue gases like NOx and SOx, and equipment corrosion by the MEA solution. As a result, solid supported capture materials are currently being investigated as alternatives to aqueous MEA solutions for CO2 capture. We study the adsorption of MEA on TiO2 using synchrotron based UHV X-ray photoelectron spectroscopy (XPS) as well as Scanning Tunneling Microscopy (STM) and also its potential for CO2 capture with ambient-pressure XPS. Understanding the bonding of this simple CO2 capture molecules to a solid support on a molecular level can explain why this model system lacks the ability for CO2 capture.
After capturing the CO2 it can, for example, be used for dry-reforming of methane to form syn-gas – a mixture of H2 and CO – which can be used as a hydrogen source or for Fisher-Tropsch synthesis of fuels. In earlier studies it was shown, that reduced mixed MgO/NiO catalysts show better long-term stability for methane reforming than conventional Ni catalysts. In order to explore the favorable properties of these mixed-oxide catalysts we have taken a model catalyst approach: MgO plus NiO or CoO thin films were deposited onto Mo(100) and the intermixing of the oxides followed by their reduction was investigated with normal and grazing emission XPS and STM.
|Laatst gewijzigd:||22 oktober 2012 14:30| | <urn:uuid:cc939883-9dbe-428e-ac46-59f46e29195e> | 2.609375 | 546 | News (Org.) | Science & Tech. | 29.379196 | 95,599,269 |
Let algae do the dirty work.
Researchers at Rochester Institute of Technology are developing biodiesel from microalgae grown in wastewater. The project is doubly “green” because algae consume nitrates and phosphates and reduce bacteria and toxins in the water. The end result: clean wastewater and stock for a promising biofuel.
The purified wastewater can be channeled back into receiving bodies of water at treatment plants, while the biodiesel can fuel buses, construction vehicles and farm equipment. Algae could replace diesel’s telltale black puffs of exhaust with cleaner emissions low in the sulfur and particulates that accompany fossil fuels.
Algae have a lot of advantages. They are cheaper and faster to grow than corn, which requires nutrient-rich soil, fertilizer and insecticide. Factor in the fuel used to harvest and transport corn and ethanol starts to look complicated.
In contrast, algae are much simpler organisms. They use photosynthesis to convert sunlight into energy. They need only water—ponds or tanks to grow in—sunlight and carbon dioxide.
“Algae—as a renewable feedstock—grow a lot quicker than crops of corn or soybeans,” says Eric Lannan, who is working on his master’s degree in mechanical engineering at RIT. “We can start a new batch of algae about every seven days. It’s a more continuous source that could offset 50 percent of our total gas use for equipment that uses diesel.”
Cold weather is an issue for biodiesel fuels.
“The one big drawback is that biodiesel does freeze at a higher temperature,” says Jeff Lodge, associate professor of biological sciences at RIT. “It doesn’t matter what kind of diesel fuel you have, if it gets too cold, the engine’s not starting. It gels up. It’s possible to blend various types of biodiesel—algae derived with soybeans or some other type—to generate a biodiesel with a more favorable pour point that flows easily.”
Lannan’s graduate research in biofuels led him to Lodge’s biology lab. With the help of chemistry major Emily Young, they isolated and extracted valuable fats, or lipids, algae produce and yielded tiny amounts of a golden-colored biodiesel. They are growing the alga strain Scenedesmus, a single-cell organism, using wastewater from the Frank E. Van Lare Wastewater Treatment Plant in Irondequoit, N.Y.
“It’s key to what we’re doing here,” Lodge says. “Algae will take out all the ammonia—99 percent—88 percent of the nitrate and 99 percent of the phosphate from the wastewater — all those nutrients you worry about dumping into the receiving water. In three to five days, pathogens are gone. We’ve got data to show that the coliform counts are dramatically reduced below the level that’s allowed to go out into Lake Ontario.”
Assemblyman Joseph Morelle, whose district includes Irondequoit, applauds RIT’s initiative. “Innovations developed at great academic institutions such as RIT will be key to solving many of the challenges we face, from revitalizing the upstate economy to the creation of clean, renewable energy sources for the future. Professor Lodge and Eric Lannan’s research bridges the gap between cost efficiency and environmental conservation and is a perfect example of how old problems can yield to new and creative solutions.”
Lodge and Lannan ramped up their algae production from 30 gallons of wastewater in a lab at RIT to 100 gallons in a 4-foot-by-7-foot long tank at Environmental Energy Technologies, an RIT spinoff. Lannan’s graduate thesis advisor Ali Ogut, professor of mechanical engineering, is the company’s president and CTO. In the spring, the researchers will build a mobile greenhouse at the Irondequoit wastewater treatment plant and scale up production to as much as 1,000 gallons of wastewater.
Northern Biodiesel, located in Wayne County, will purify the lipids from the algae and convert them into biodiesel for the RIT researchers.
Susan Gawlowicz | EurekAlert!
Upcycling of PET Bottles: New Ideas for Resource Cycles in Germany
25.06.2018 | Fraunhofer-Institut für Betriebsfestigkeit und Systemzuverlässigkeit LBF
Dry landscapes can increase disease transmission
20.06.2018 | Forschungsverbund Berlin e.V.
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
16.07.2018 | Physics and Astronomy
16.07.2018 | Life Sciences
16.07.2018 | Earth Sciences | <urn:uuid:9db80501-fc0e-4139-82ae-cf5a9dae7552> | 3.421875 | 1,553 | Content Listing | Science & Tech. | 43.623971 | 95,599,281 |
Climate change shows in shrinking Antarctic snows
Published : 15 Jan 2017, 14:41
Vast icy rock peaks tower above Argentina's Carlini research base in Antarctica. But scientists who have worked here for decades say the glaciers are less icy than they once were.
For international experts stationed at the base, the frozen southern continent is a good gauge of climate change.
"When I used to come to Antarctica in the 1990s, it never used to rain," said Rodolfo Sanchez, director of the Argentine Antarctic Institute (IAA).
"Now it rains regularly instead of snowing," he told AFP during an Argentine government visit to King George Island, off the tip of the western Antarctic peninsula.
Scientists monitoring conditions at the base say the average temperature here has increased by 2.5 degrees Celsius (4.5 degrees Fahrenheit) over the past century.
"The glacier used to reach all the way to the shore," Sanchez says. "Now there is a 500-meter (550-yard) wide beach."
Dark scars of rock are showing through what were once spotless sheets of white snow on the glaciers' flanks.
"Antarctica is a thermometer that shows how the world is changing," said Adriana Gulisano, a physicist at Argentina's National Antarctic Directorate.
"There is no place where climate change is more in evidence."
- Wildlife signs -
Local wildlife also appears to reflect to the change.
Scientists at the Carlini base say a pair of yellow-throated King penguins have swum up to mate nearby for the past three years.
Although the theory is not confirmed, they suspect another sign of climate change. The species had previously been thought to be restricted to warmer spots on the Falkland Islands and the Argentine mainland.
Technician Luis Souza, 56, has divided his time since 1979 between Buenos Aires and the Carlini base, where he has studied migrating birds: cormorants, gulls and penguins.
"There are more and more birds coming here every year," he said.
More crucially, scientists say melting ice is disrupting the breeding of krill, a shrimp-like creature that serves as food for numerous species.
"Less ice means fewer krill for the whales, penguins and seals," said Sanchez. "The whole food chain is affected."
- Dinosaurs in ice -
Various countries maintain bases in Antarctica, a shared space for scientific research under a 1959 international treaty.
Former military bases have become laboratories for research into the planet's future.
The Carlini base's red cabins nestle at the foot of a mountain range known as "The Three Brothers."
Below the structures, the shore is strewn with black volcanic rocks.
The population of scientists and military logistics personnel at the 13 Argentina bases in Antarctica can reach 1,000 at busy times.
Supplies are brought in by boat or helicopter. Garbage is stored and taken away by an icebreaker.
Other kinds of experts are also busy in Antarctica, a continent roamed by dinosaurs 75 million years ago.
"The signs are under the ice," said paleontologist Marcelo Reguero cryptically. He has been working in Antarctica since 1986.
- Greenhouse gas flows south -
Although Antarctica lies thousands of miles from any industrialized area, a recent study by Argentine and Italian scientists found that levels of harmful carbon dioxide gas are rising all the same.
That is "due to the circulation of currents in the atmosphere" bringing the gas from emissions elsewhere all the way down to Antarctica.
But closer to the South Pole in the heart of the white continent, the trend is the opposite, Gulisano said average temperatures are getting colder.
"Why?" she asked. "That is the million-dollar question. We are working on it."
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CORVALLIS, Ore. – Incentives that are designed to enable smarter use of the ocean while also protecting marine ecosystems can and do work, and offer significant hope to help address the multiple environmental threats facing the world’s oceans, researchers conclude in a new analysis.
Whether economic or social, incentive-based solutions may be one of the best options for progress in reducing impacts from overfishing, climate change, ocean acidification and pollution, researchers from Oregon State University and Princeton University say in a new report published this week in Proceedings of the National Academy of Sciences.
And positive incentives – the “carrot” – work better than negative incentives, or the “stick.”
Part of the reason for optimism, the researchers report, is changing awareness, attitudes and social norms around the world, in which resource users and consumers are becoming more informed about environmental issues and demanding action to address them. That sets the stage for economic incentives that can convert near-disaster situations into sustainable fisheries, cleaner water and long-term solutions.
“As we note in this report, the ocean is becoming higher, warmer, stormier, more acidic, lower in dissolved oxygen and overfished,” said Jane Lubchenco, the distinguished university professor in the College of Science and advisor in marine studies at Oregon State University, lead author of the new report, and U.S. science envoy for the ocean at the Department of State.
“The threats facing the ocean are enormous, and can seem overwhelming. But there’s actually reason for hope, and it’s based on what we’ve learned about the use of incentives to change the way people, nations and institutions behave. We believe it’s possible to make that transition from a vicious to a virtuous cycle. Getting incentives right can flip a disaster to a resounding success.”
Simon A. Levin, the James S. McDonnell distinguished university professor in ecology and evolutionary biology at Princeton University and co-author of the publication, had a similar perspective.
“It is really very exciting that what, until recently, was theoretical optimism is proving to really work,” Levin said. “This gives me great hope for the future.”
The stakes are huge, the scientists point out in their study.
The global market value of marine and coastal resources and industries is about $3 trillion a year; more than 3 billion people depend on fish for a major source of protein; and marine fisheries involve more than 200 million people. Ocean and coastal ecosystems provide food, oxygen, climate regulation, pest control, recreational and cultural value.
“Given the importance of marine resources, many of the 150 or more coastal nations, especially those in the developing world, are searching for new approaches to economic development, poverty alleviation and food security,” said Elizabeth Cerny-Chipman, a postdoctoral scholar working with Lubchenco. “Our findings can provide guidance to them about how to develop sustainably.”
In recent years, the researchers said in their report, new incentive systems have been developed that tap into people’s desires for both economic sustainability and global environmental protection. In many cases, individuals, scientists, faith communities, businesses, nonprofit organizations and governments are all changing in ways that reward desirable and dissuade undesirable behaviors.
One of the leading examples of progress is the use of “rights-based fisheries.” Instead of a traditional “race to fish” concept based on limited seasons, this growing movement allows fishers to receive a guaranteed fraction of the catch, benefit from a well-managed, healthy fishery and become part of a peer group in which cheating is not tolerated.
There are now more than 200 rights-based fisheries covering more than 500 species among 40 countries, the report noted. One was implemented in the Gulf of Mexico red snapper commercial fishery, which was on the brink of collapse after decades of overfishing. A rights-based plan implemented in 2007 has tripled the spawning potential, doubled catch limits and increased fishery revenue by 70 percent.
“Multiple turn-around stories in fisheries attest to the potential to end overfishing, recover depleted species, achieve healthier ocean ecosystems, and bring economic benefit to fishermen and coastal communities,” said Lubchenco. “It is possible to have your fish and eat them too.”
A success story used by some nations has been combining “territorial use rights in fisheries,” which assign exclusive fishing access in a particular place to certain individuals or communities, together with adjacent marine reserves. Fish recover inside the no-take reserve and “spillover” to the adjacent fished area outside the reserve. Another concept of incentives has been “debt for nature” swaps used in some nations, in which foreign debt is exchanged for protection of the ocean.
“In parallel to a change in economic incentives,” said Jessica Reimer, a graduate research assistant with Lubchenco, “there have been changes in behavioral incentives and social norms, such as altruism, ethical values, and other types of motivation that can be powerful drivers of change.”
The European Union, based on strong environmental support among its public, has issued warnings and trade sanctions against countries that engage in illegal, unregulated and unreported fishing. In the U.S., some of the nation’s largest retailers, in efforts to improve their image with consumers, have moved toward sale of only certified sustainable seafood.
Incentives are not a new idea, the researchers noted. But they emphasize that their power may have been under-appreciated.
“Recognizing the extent to which a change in incentives can be explicitly used to achieve outcomes related to biodiversity, ecosystem health and sustainability . . . holds particular promise for conservation and management efforts in the ocean,” they wrote in their conclusion.
Source: OSU College of Science, 11-28-16, By David Stauth
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This video is adapted from an intriguing episode of Hubblecast. nature’s telescopes. It explores a phenomenon called gravitational lensing. The gravitational force of a galaxy, full of stars, gas, dark matter, and dust, is so enormous that it affects the region it sits in and distorts the very fabric of the surrounding space.
It isn’t only galaxies that do this. Any object that has mass distorts the space around it with its gravity, from large galaxy clusters down to individual stars. In space, light travels invariably along straight lines. But what is a straight line? Well, it is the shortest distance between two points. But in a curved space, the shortest distance between two points may not look particularly straight to us.
Now what that means is that when light passes very near by a massive object that curves the space around it, the light ray is bent. As a result, this massive object, or rather the curved space around it produced by its gravity, acts like a lens; a gravitational lens that deflects light into our telescopes that would have otherwise never made it there.
This deflection means that distant and faint objects can suddenly be seen peeking from around the edge of a nearer “lens” — although they may look quite different than expected.
We see distant galaxies that have been “lensed” as arcs on the sky around their lenses. For example, the arc around this galaxy cluster is not a photographic error, but a second more distant galaxy — deformed, but visible.
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In this chapter we continue to model multispecies assemblages. But in contrast to the previous chapter, the two-species model developed here consists of a predator population and a prey population (Fig. 18.1). Both are present within a given area with a specified carrying capacity.
KeywordsMigration Rate Prey Population Carry Capacity Predator Population Consume Rate
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The firn layers of the Greenland ice sheet might store less meltwater than previously assumed. Researchers from the USA, Denmark and the University of Zurich fear that this could lead to increased release of the meltwater into the oceans.
The near-surface layers of the Greenland ice sheet are made up of snow that is gradually being converted into glacier ice. In Greenland this firn layer is up to 80 m thick.
As researchers from Denmark, the USA and the University of Zurich have demonstrated, the current atmospheric warming is changing this firn layer such that resulting meltwater is being released faster than previously anticipated.
“Basically our research shows that the firn reacts fast to a changing climate. Its ability to limit mass loss of the ice sheet by retaining meltwater could be smaller than previously assumed”, sums up Horst Machguth, lead author of the study by the University of Zurich.
The researchers travelled to Greenland to investigate the impact of recent atmospheric warming on the structure of near-surface snow and ice layers, called firn. Over the course of three expeditions on the ice sheet, the researchers traversed several hundred kilometres to map the structure of the firn layers with a radar unit and by drilling regularly-spaced firn cores.
Firn layer acts sponge-like
Earlier research has shown that the firn layer acts similar to a sponge. It stores meltwater percolating down into the firn from the surface in what are referred to as ‘ice lenses’. “It is unknown how the firn reacted to the recent very warm summer in Greenland. Our research aims to clarify whether the firn was indeed capable of retaining the meltwater, or whether the sponge has been overwhelmed.”
The scientists drilled numerous 20 metre-deep cores to sample the firn, also targeting sites where similar cores had been drilled 15 to 20 years ago. At many locations, a comparison of the new and old cores revealed substantially more ice lenses than in the past and that the firn stored the meltwater similar to a sponge. But this was not the case everywhere. Cores drilled at lower elevations indicated that the exceptional amounts of meltwater formed a surprisingly massive ice layer directly below the ice sheet surface.
Meltwater no longer percolating
“It appears that the intensive and repeated entry of meltwater formed numerous ice lenses, which ultimately hindered percolation of further meltwater”, says Dirk van As, a co-author of the study from the Geological Survey in Denmark and Greenland. As a result, the many small lenses grew to form an ice layer of several meters in thickness that now acts as a lid on top of otherwise sponge-like firn.
Radar measurements identified that this layer was continuous over dozens of kilometers. New meltwater, hitting that lid of ice was unable to percolate into the firn and remained at the surface. Satellite imagery shows that the water prevented from percolating collected at the surface, where it formed rivers that flow towards the margin of the ice sheet.
“In contrast to storing meltwater in porous firn, this mechanism increases runoff from the ice sheet”, explains Mike MacFerrin, second-author of the study and a researcher at the University of Colorado at Boulder.
“This process has not previously been observed in Greenland. The total extent of this ice lid capping the ice sheet firn remains unknown. For this reason, the amount of additional ice sheet runoff associated with this newly observed process cannot yet be quantified.” However, similar changes in firn structure have already been observed in the Canadian Arctic, which leads to the conclusion that this phenomenon could be widespread.
Machguth, H., M. MacFerrin, D. van As, J. E. Box, C. Charalampidis, W. Colgan, R. S. Fausto, H. A. J. Meijer, E. Mosley-Thompson and R. S. W. van de Wal. Greenland meltwater storage in firn limited by near-surface ice formation. Nature Climate Change. Doi: 10.1038/NCLIMATE2899
World Glacier Monitoring Service
Department of Geography
University of Zurich.
Dirk van As
Geological Survey of Denmark and Greenland (GEUS) Copenhagen, Denmark
Cooperative Institute for Research in Environmental Sciences (CIRES)
University of Colorado at Boulder, USA
Beat Müller | Universität Zürich
New research calculates capacity of North American forests to sequester carbon
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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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16.07.2018 | Earth Sciences | <urn:uuid:88c16ae4-cf91-457b-8d7f-cbf708cbfc88> | 4.0625 | 1,557 | Content Listing | Science & Tech. | 43.66991 | 95,599,408 |
So far, astrophysicists thought that super-massive black holes can only influence their immediate surroundings. A collaboration of scientists at the Heidelberg Institute for Theoretical Studies (HITS) and in Canada and the US now discovered that diffuse gas in the universe can absorb luminous gamma-ray emission from black holes, heating it up strongly.
A supermassive black hole is surrounded by a dust ring (torus). The collapse of gas onto the black hole launches an energetic jet of matter and radiation, which is transported over cosmological distances. A jet that is pointing into our direction is called a "blazar". copyright: ESA/NASA, the AVO project and Paolo Padovani
Simulated line forest of a quasar spectrum. The blue spectrum represents a universe without blazar heating, the red one a universe with blazar heating. It is evident that the additional heating process ionizes neutral hydrogen, implying less absorption of the UV light emitted by the quasar. Picture: HITS
This surprising result has important implications for the formation of structures in the universe. The results have just been published in "The Astrophysical Journal“ and „Monthly Notices of the Royal Astronomical Society”.
Every galaxy hosts a supermassive black hole at its center. Such black holes can emit high-energy gamma rays and are then called blazars. Whereas other radiation such as visible light and radio waves traverses the universe without problems, this is not the case for high-energy gamma rays. This particular radiation interacts with the optical light that is emitted by galaxies, transforming it into the elementary particles electrons and positrons.
Initially, these elementary particles move almost at the speed of light. But as they are slowed down by the ambient diffuse gas, their energy is converted into heat, just like in other braking processes. As a result, the surrounding gas is heated efficiently. In fact, the temperature of the gas at mean density becomes ten times higher, and in underdense regions more than one hundred times higher than previously thought.
A Journey into the Cosmic Youth
"Blazars rewrite the thermal history of the universe", emphasizes Dr. Christoph Pfrommer (HITS), one of the authors. But how can this idea be tested? In the optical spectra of quasars there is a plethora of lines, called the "line forest". The forest originates from the absorption of ultra-violet light by neutral hydrogen in the young Universe. If the gas becomes hotter, weak lines in the forest are broadened. This effect represents an excellent opportunity to measure temperatures in the early Universe, while it was still growing up.
The astrophysicists at HITS checked this newly postulated heating process for the first time with detailed supercomputer simulations of the cosmological growth of structures. Surprisingly, the lines were broadened just enough so that their properties perfectly matched those of the observed lines. "This allows us to elegantly solve a long-standing problem with the quasar data", says Dr. Ewald Puchwein, who conducted the large simulations on the supercomputer at HITS.
How Black Holes Influence the Formation of Galaxies
What are the further consequences of this new heating process? The forest of lines in the quasar spectra originates from density fluctuations in the Universe. In the course of cosmic evolution, the densest fluctuations collapse to form galaxies and galaxy clusters, as observed in the local Universe. Diffuse gas that is too hot cannot collapse. Hence, the formation of dwarf galaxies is slowed or even entirely suppressed. This could be the key to the solution of another long-standing problem in the theory of galaxy formation: why do we observe fewer dwarf galaxies in the vicinity of the Milky Way and in the underdense regions than predicted by cosmological simulations?
Prof. Volker Springel, scientific group leader at HITS, explains: "The process of blazar heating is especially exciting since this single effect is able to simultaneously solve several different puzzles in cosmological structure formation." The group plans to further improve their simulation models for a still deeper understanding of the nature of blazar heating and its implications for today's Universe.Press contact:
The Cosmological Impact of Luminous TeV Blazars III: Implications for Galaxy Clusters and the Formation of Dwarf Galaxies. C. Pfrommer, P. Chang, and A. E. Broderick, 2012, ApJ, in print, arXiv:1106.5505 http://arxiv.org/abs/1106.5505
The Cosmological Impact of Luminous TeV Blazars II: Rewriting the Thermal History of the Intergalactic Medium. P. Chang, A. E. Broderick, and C. Pfrommer, 2012, ApJ, in print, arXiv:1106.5504 http://arxiv.org/abs/1106.5504
The Cosmological Impact of Luminous TeV Blazars I: Implications of Plasma Instabilities for the Intergalactic Magnetic Field and Extragalactic Gamma-Ray Background. A. E. Broderick, P. Chang, and C. Pfrommer, 2012, ApJ, in print, arXiv:1106.5494 http://arxiv.org/abs/1106.5494
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16.07.2018 | Earth Sciences | <urn:uuid:54d83aa5-f799-409d-9819-0add3e00d8ca> | 3.96875 | 1,763 | Content Listing | Science & Tech. | 40.332973 | 95,599,409 |
Emerald ash borer, Agrilus planipennis Fairmaire (Coleoptera: Buprestidae), has killed millions of ash (Fraxinus sp.) trees in North America since its discovery in Michigan in 2002. Efficient methods to detect low-density A. planipennis populations remain a critical priority for regulatory and resource management agencies. We compared the density of adult A. planipennis captured on sticky bands and larval density among ash trees that were girdled for 1 or 2 yr, wounded, exposed to the stress-elicitor methyl jasmonate, baited with Manuka oil lures, or left untreated. Studies were conducted at four sites in 2006 and 2007, where A. planipennis densities on untreated trees ranged from very low to moderate. In 2006, 1-yr girdled trees captured significantly more adult A. planipennis and had higher larval densities than untreated control trees or trees treated with methyl jasmonate or Manuka oil. Open-grown trees captured significantly more A. planipennis beetles than partially or fully shaded trees. In 2007, A. planipennis population levels and captures of adult A. planipennis were substantially higher than in 2006. The density of adults captured on sticky bands did not differ significantly among canopy exposure classes or treatments in 2007. Larval density was significantly higher in untreated, wounded, and 1-yr girdled trees (girdled in 2007) than in 2-yr girdled trees (girdled in 2006), where most phloem was consumed by A. planipennis larvae the previous year. A total of 36 trees (32 in 2006, 4 in 2007) caught no beetles, but 16 of those trees (13 in 2006, 3 in 2007) had A. planipennis larvae. In 2006, there was a positive linear relationship between the density of adults captured on sticky bands and larval density in trees. Our results show that freshly girdled and open grown trees were most attractive to A. planipennis, especially at low-density sites. If girdled trees are used for A. planipennis detection or survey, debarking trees to locate larval galleries is crucial.
Mendeley saves you time finding and organizing research
Choose a citation style from the tabs below | <urn:uuid:06f7637f-d2d2-4fd7-a015-afa101ee9c76> | 2.78125 | 479 | Academic Writing | Science & Tech. | 44.035886 | 95,599,451 |
In the Software industry, Most of the clients have a main requirement which is
“We want the system to be secured”.
Security is a non-functional property of the system, the main goal for securing the system to make this system dependable. So, we can depend on this system and it can perform its excepted functions as required and specified.
Therefore, it is mandatory to run the security testing procedures to ensure that we can depend on this system, but we need also to consider some functional requirements on writing requirements specifications document that help to obtain this goal.
Definition of Security testing
“Security testing is a process to determine that an information system protects data and maintains functionality as intended” Wikipedia
We can summarize that we need security testing on the following:
- Information and access security. Security tests help to find out loopholes that can cause loss of important information or allow the intruder into the systems.
- System stability and availability. Security testing helps to improve the system and finally helps it to work for a longer time (or it will work without hassles for the estimated time).
- System integrity. If involved in the early stages of the development lifecycle, security testing allows eliminating possible flaws in system design and implementation. We need to consider security aspects in the architecture phase.
- Economic efficiency. It’s much cheaper to prevent the possible problem rather than to strive for resolving it and its consequences.
The main objective of software security analysis and testing is the verification that the software exhibits the following properties and behaviors:
- Its behavior is predictable and secure.
- It exposes no vulnerabilities or weaknesses (ideally it contains no vulnerabilities or weaknesses, exposed or not).
- Its error and exception handling routines enable it to maintain a secure state when confronted by attack patterns or intentional faults.
- It satisfies all of its specified and implicit nonfunctional security requirements.
- It does not violate any specified security constraints.
- As much of its runtime-interpretable source code and bytecode as possible has been obscured or obfuscated to deter reverse engineering. | <urn:uuid:0e66ef0b-b89b-44b8-b722-d75a68c8a1f2> | 2.8125 | 426 | Knowledge Article | Software Dev. | 20.073111 | 95,599,462 |
Since astronomers first measured the size of an extrasolar planet seventeen years ago, they have struggled to answer the question: how did the largest planets get to be so large? Thanks to the recent discovery of twin planets by a University of Hawaii Institute for Astronomy team lead by graduate student Samuel Grunblatt, we are getting closer to an answer.
Gas giant planets are primarily made out of hydrogen and helium, and are at least 4 times the diameter of Earth. Gas giant planets that orbit scorchingly close to their host stars are known as "hot Jupiters". These planets have masses similar to Jupiter and Saturn, but tend to be much larger - some are puffed up to sizes even larger than the smallest stars.
The unusually large sizes of these planets are likely related to heat flowing in and out of the their atmospheres, and several theories have been developed to explain this process. "However, since we don't have millions of years to see how a particular planetary system evolves, planet inflation theories have been difficult to prove or disprove," said Grunblatt.
To solve this issue, Grunblatt searched through data collected by NASA's K2 Mission to hunt for hot Jupiters orbiting red giant stars. These stars, which are in the late stages of their lives, become themselves significantly larger over their companion planet's lifetime. Following a theory put forth by Eric Lopez of NASA's Goddard Space Flight Center, hot Jupiters orbiting red giant stars should be highly inflated if direct energy input from the host star is the dominant process inflating planets.
The search has now revealed two planets, each orbiting their host star with a period of approximately 9 days. Using stellar oscillations to precisely calculate the radii of both the stars and planets, the team found that the planets are 30% larger than Jupiter. Observations using the W. M. Keck Observatory on Maunakea also showed that, despite their large sizes, the planets were only half as massive as Jupiter. Remarkably, the two planets are near twins in terms of their orbital periods, radii, and masses.
Using models to track the evolution of the planets and their stars over time, the team calculated the planets' efficiency at absorbing heat from the star and transferring it to their deep interiors, causing the whole planet to expand in size and decrease in density. Their findings show that these planets likely needed the increased radiation from the red giant star to inflate, but the amount of radiation absorbed was also lower than expected.
It is risky to attempt to reach strong conclusions with only two examples. But these results begin to rule out some explanations of planet inflation, and are consistent with a scenario where planets are directly inflated by the heat from their host stars. The mounting scientific evidence seems to suggest that stellar radiation alone can directly alter the size and density of a planet.
Our own Sun will eventually become a red giant star, so it's important to quantify the effect its evolution will have on the rest of the Solar System. "Studying how stellar evolution affects planets is a new frontier, both in other solar systems as well as our own," said Grunblatt. "With a better idea of how planets respond to these changes, we can start to determine how the Sun's evolution will affect the atmosphere, oceans, and life here on Earth."
The search for gas giant planets around red giant stars continues since additional systems could conclusively distinguish between planet inflation scenarios. Grunblatt and his team have been awarded time with the NASA Spitzer Space Telescope to measure the sizes of these twin planets more accurately. In addition, the search for planets around red giants with the NASA K2 Mission will continue for at least another year, and NASA's Transiting Exoplanet Survey Satellite (TESS), launching in 2018, will observe hundreds of thousands of red giants across the entire sky.
"Seeing double with K2: Testing re-inflation with two remarkably similar planets orbiting red giant stars" has been published in November 27th edition of The Astronomical Journal.
Explore further: Astronomers discover a giant inflated exoplanet orbiting a distant star
Samuel K. Grunblatt et al. Seeing Double with K2: Testing Re-inflation with Two Remarkably Similar Planets around Red Giant Branch Stars, The Astronomical Journal (2017). DOI: 10.3847/1538-3881/aa932d , https://arxiv.org/abs/1706.05865 | <urn:uuid:6b212c6f-2b00-4505-8e0b-a88d3fe3fdc7> | 4.375 | 922 | Knowledge Article | Science & Tech. | 42.37938 | 95,599,489 |
Look closely. The cosmic dust captured in this infrared photo of the Milky Way may be brimming with space grease.
Credit: NASA/ JPL-Caltech
Space: It’s dark, cold and, in most parts of the galaxy, probably pretty sticky.
Swirled amid the dust, soot and electromagnetic radiation that sits among the stars of the Milky Way, there is also a whole mess of toxic grease. This “space grease” — actually an oily form of hydrogen-bound carbon called aliphatic carbon — is one of several types of carbon leaked into empty space by blazing stars, and may be among the key ingredients in the formation of new stars and planets, astronomers say.
Precisely how much grease is out there lubing up the Milky Way? Scientists haven’t known for sure, but a new paper published June 13 in the journal Monthly Notices of the Royal Astronomical Society proposes an answer: enough grease to really mess up the windshield on your spaceship. [Interstellar Travel: 7 Futuristic Spacecrafts to Explore the Cosmos]
According to a team of astronomers from the University of New South Wales (UNSW) in Australia and Ege Universityin Turkey, there may be five times more space grease permeating the Milky Way than previous estimates indicated. By creating a space-grease proxy in their laboratory and comparing its composition to previous observations of the galaxy, the researchers found that there may be about 11 billion trillion trillion tons (or 11 with 33 zeros after it) of greasy carbon molecules in our galaxy — the equivalent of 40 trillion trillion trillion packs of butter.
“This space grease is not the kind of thing you’d want to spread on a slice of toast,” study author Tim Schmidt, a professor of chemistry at UNSW, said in a statement. “It’s dirty, likely toxic and only forms in the environment of interstellar space — and our laboratory.” (Schmidt added that the solar wind likely keeps this grease from gumming up our own solar system.)
In their new study, Schmidt and his colleagues took a close-up look at space grease by making some of their own. To mimic the process by which stars synthesize gases and blast them into the interstellar medium (that’s what astronomers call the stuff between stars), the team expanded a carbon-rich plasma, or ionized gas, in a vacuum chamber. From this plasma came a dust byproduct sort of like the interstellar dust where space grease spreads.
Using spectroscopy, the team determined how strongly the greasy dust absorbed certain wavelengths of infrared light, which would affect how instruments can pick up on its presence. With this data, the team could then look to prior observations of nearby stars to determine “how much greasy carbon is in the line of sight of various stars,” Schmidt told The Guardian.
Through these observations, the researchers determined that there are about 100 space-grease atoms for every 1 million hydrogen atoms — accounting for between one-quarter and one-half of the galaxy’s interstellar carbon.
This knowledge of space grease could help scientists understand our entire galaxy better, the researchers wrote. Carbon is thought to be an essential building block of life, so knowing how much carbon is available in various forms throughout the interstellar medium could give scientists a clue to the likelihood that other life-harboring solar systems could form (or already have formed) in the Milky Way. For Schmidt, the results of this study are cause for optimism.
“It’s intriguing that organic material of this kind — material that gets incorporated into planetary systems — is so abundant,” Schmidt said.
Originally published on Live Science. | <urn:uuid:a054e381-7d67-4832-8de2-e1a7626a3832> | 3.375 | 765 | News Article | Science & Tech. | 39.547218 | 95,599,507 |
Magnetic, temperature and structural studies have yielded new insights on the material sodium iridium oxide
RIKEN scientists have discovered a new state of matter with unusual magnetic properties—its constituent electrons are in a continuous state of flux, even at incredibly cold temperatures.
As electrons spin, they generate a magnetic field which can point ‘up’ or ‘down’. Within solid materials, an electron will generally try to adopt the opposite spin orientation to its neighbor, just as two bar magnets will flip around so that north and south poles line up next to each other.
In more common lattice structures, where atoms stack up like oranges on a greengrocers stall, it’s easy for electrons to achieve this ordered arrangement. But in certain materials, the arrangement of atoms can make it impossible for the electrons to line up with all of their neighbors, and they are said to be ‘frustrated’.
One example of a frustrated material contains a network of atoms arranged into corner-sharing triangles. This is called a kagome structure after a type of Japanese basket that has the same pattern (Fig. 1).
The electrons’ response to this frustration is to constantly flip their magnetic fields to reduce the repulsion between them. In this ‘quantum spin-liquid state’, the quantum effect is expected to stop flipping electrons from freezing out into a static arrangement even at absolute zero (-273.15 ˚C—the coldest temperature possible). Several materials have been claimed to contain possible quantum spin-liquid states, but none have been confirmed.
Hidenori Takagi and Yoshihiko Okamoto of RIKEN’s Discovery Research Institute, Wako, and colleagues, have now found that sodium iridium oxide (Na4Ir3O8) exhibits quantum spin-liquid behavior, even when cooled to -271 ˚C. This was confirmed by magnetic, temperature and structural studies, involving both neutron and x-ray diffraction.
The material contains a network of iridium atoms that form a three-dimensional pattern of corner-shared triangles—dubbed a hyperkagome lattice (Fig. 2), which can be viewed as a slightly twisted—but different structure—to the kagome structure, explains Takagi. Theoretical calculations are consistent with this type of structure showing spin-liquid behavior.
“We believe it is the strongest candidate [for a quantum spin liquid],” says Takagi.
The scientists say that the material is “a fascinating playground for quantum magnetism”, and now hope to study the spin-liquid state further. This should to help build up a detailed description of the phenomenon using quantum theory, describing on a subatomic level exactly how the spinning electrons interact with each other.
1. Okamoto, Y., Nohara, M., Aruga-Katori, H. & Takagi, H. Spin-liquid state in the S = 1/2 hyperkagome antiferromagnet Na4Ir3O8. Physical Review Letters 99, 137207 (2007).
In borophene, boundaries are no barrier
17.07.2018 | Rice University
Research finds new molecular structures in boron-based nanoclusters
13.07.2018 | Brown University
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
17.07.2018 | Information Technology
17.07.2018 | Materials Sciences
17.07.2018 | Power and Electrical Engineering | <urn:uuid:f1fef59c-3aaf-4f8e-afab-f778ba35b2c8> | 3.078125 | 1,263 | Content Listing | Science & Tech. | 37.952328 | 95,599,520 |
Has volcanic activity been increasing?
The Global Volcanism Program does not see any evidence that volcanic activity is actually increasing. Data about eruptions compiled by the Smithsonian since 1968 provide context for assessing issues of regional and global volcanism. The following figures and discussion below are modified from an introductory section in Siebert et al. (2010); data is through 2009. Please do not reproduce the figures below without all of the accompanying analysis and proper citation (links are preferred).
There is great value in knowing the recent volcanological record, but its limitations are not as apparent. Readers are strongly cautioned against mistaking the record for the reality. Perhaps the best illustration of these limitations come from the data themselves. The last 600 years of apparent global volcanism can be displayed by plotting the number of volcanoes known to have been active each year (figure 1). At first glance the nearly exponential increase through recent centuries suggests that the planet may soon be overwhelmed by volcanic activity, but this increase tracks the striking growth of global population (dashed line on figure 1) that has spread potential observers of eruptions over much of the Earth and the technological advances that have facilitated reporting of those eruptions.
Another indicator of the growth of the record is the increase in the total number of known historically active volcanoes (upper line on figure 1). These are not newly-formed volcanoes, but already established features (or volcanic fields) that clearly had numerous previous eruptions. If a list had been continuously kept, about 2000 years ago it would have contained only the names of nine Mediterranean volcanoes and West Africa's Mount Cameroon. In the next ten centuries the list would have grown by only 30 names, 18 of them Japanese. Although newly settled Iceland soon added seven volcanoes, the list totaled only 63 by 1400 CE, where figure 1 begins.
A dramatic increase in both the number of historically active volcanoes and recorded eruptions took place about 1500 CE. These resulted in part from the great Spanish/Portuguese marine explorations – the Age of Discovery – around the end of the 15th century, when explorers opened Latin America and much of the western Pacific to European record-keeping. Perhaps equally important was the development and widespread distribution of the printing press in the late 15th century, markedly increasing the likelihood that new volcanological records would survive. Through the 17th and into the early 18th century the recognition of additional active volcanoes generally corresponded with steadily increasing eruption reports. By the 18th century global trade was flourishing, the Industrial Revolution was under way, and the heightened reporting of eruptions noticeably accelerated the discovery of new volcanoes. The list has continued to grow, with several important volcanic regions such as New Zealand, Alaska, and Hawaii being unrepresented until the last 250 years.
The suggestion above is that the apparent trend is closely related to increases in population and communication, and that it actually represents an increased reporting of eruptions, not actual increased volcanism: more observers, in wider geographic distribution, with better communication, and broader publication. The last 200 years (figure 2), with humans distributed over most of the globe and relatively efficient communications, would seem to be the best suited to search for episodic trends. However, even in the last two centuries reporting factors overshadow any real trends in volcanism, as detailed below. Additional strong evidence that the historical trend in volcanism is more apparent than real comes from the lower plot of figure 2. Here only the larger eruptions generating at least 0.1 km3 of tephra (VEI >= 4), the fragmental products of explosive eruptions, are plotted. The effects of these larger events are often regional, and therefore less likely to escape documentation even in remote areas. The frequency of these events has remained impressively constant for more than a century, and contrasts strongly with the apparent increase of smaller eruptions with time.The effects of these large eruptions are far reaching and thus they are less likely to escape documentation even in remote areas.
Inspection of data from the past 200 years shows some major "peaks and valleys" which suggest global pulsations. A closer look at the two largest valleys, however, shows that they coincide with the two World Wars, when people (including publishers) were preoccupied with other things. Great economic crises, like wars, might also be expected to interfere with the reporting of natural events. One of the most precipitous drops in reported volcanism followed the stock market collapse of 1929 and during the ensuing Great Depression. From the late 1920's to the early 1930's, every volcanic region in the world – except those of Russia, Melanesia, and the West Indies – showed a drop in reported active volcanoes. In the war years of 1941-45 the number reported active in the western Pacific and Indonesia dropped by nearly one-third from the preceding 5 years, while regions less affected by the war showed little change. With more observers in more remote areas during World War II, it seems likely that more eruptions than normal were actually witnessed, but it is easy to appreciate why many of these reports do not survive in the available literature.
If these apparent drops in activity are caused by decreased human attention to volcanoes, then it is reasonable to expect that increased attention after major newsworthy eruptions should result in above-average numbers being reported in the literature. The 1902 disasters at Mont Pelee (about 29,000 victims), St. Vincent, and Santa Maria were highly newsworthy events. They represent a genuine pulse in Caribbean volcanism, but we believe that the higher numbers in following years (and following Krakatau in 1883 with more than 36,000 victims) result from increased human interest. People reported events that they might not otherwise have, and editors were more likely to print those reports.
More recent major eruptions have not had this effect, in part due to more systematic cataloging and media focus on volcanic events. The newsworthiness of an eruption depends more on its location and human impact than on its size. The 1980 St. Helens eruption, for example, generated enormous media attention, while the remarkably similar 1956 eruption of Bezymianny in sparsely populated Kamchatka, in which no lives were lost, was hardly noticed by the world press. Similarly, the 1991 Pinatubo eruption, with its many fatalities and effects on nearby military bases, was front page news, but the eruption of Cerro Hudson that year in isolated southern Chile created barely a ripple in international interest.
A sharp rise in reported active volcanoes immediately post-WW II was followed by another steep increase in the early 1950s that has no obvious relationship to historic events. There is then a transition from a sequence of peaks and valleys to a more uniform pattern. This corresponds to the establishment of three venues of global eruption documentation: the beginning of the Catalog of Active Volcanoes of the World series with eruption-rich Indonesia in 1951, publication of the annual Bulletin of Volcanic Eruptions of the Volcanological Society of Japan in 1960, and Smithsonian cataloging beginning in 1968.
Yet another rise in reported activity can be noted in the late 1990s. Several new reporting effects appear to have contributed to this change. These include widespread availability of internet access and the corresponding ability to quickly and easily transmit or publish reports, the increased utilization of remote-sensing satellite data by volcano observatories, the onset of systematic reporting of ash plumes by the Volcanic Ash Advisory Centers (VAACs) to mitigate aircraft-ash interactions, and the deployment of new satellite technology starting in December 1999 with NASA's Earth Observing System (EOS) Terra satellite. Its MODIS infrared sensors have detected volcanic eruptions in sparsely populated or rarely visited regions. These collective "eyes in the skies" have detected eruptions that might otherwise go unreported. Another contributing factor may have been the onset of more systematic weekly documentation of current volcanism by the Smithsonian and USGS in 2000.
Thus, all major trends in our recent volcanological record can be reasonably explained by historical events, technological changes, and exploration influences. The apparent increase in activity reflects increases in people living near volcanoes to observe eruptions and improvements in communication technologies to report those eruptions. The best evidence that these trends are apparent rather than real comes from the record of large eruptions, whose effects are far reaching and less likely to escape documentation even in remote areas. Their constancy over the past two centuries is a better indicator of the global frequency of eruptions than the improved reporting of smaller eruptions.
Global Volcanism Program, 2013. Volcanoes of the World, v. 4.7.1. Venzke, E (ed.). Smithsonian Institution. Downloaded 18 Jul 2018. https://doi.org/10.5479/si.GVP.VOTW4-2013 | <urn:uuid:14cdd990-29ee-42d5-aa6c-dcc176140489> | 3.53125 | 1,796 | Knowledge Article | Science & Tech. | 28.528035 | 95,599,524 |
If you continue the pattern, can you predict what each of the following areas will be? Try to explain your prediction.
What is the ratio of the area of a square inscribed in a semicircle to the area of the square inscribed in the entire circle?
ABC and DEF are equilateral triangles of side 3 and 4 respectively. Construct an equilateral triangle whose area is the sum of the area of ABC and DEF.
With one cut a piece of card 16 cm by 9 cm can be made into two pieces which can be rearranged to form a square 12 cm by 12 cm. Explain how this can be done.
Three circles have a maximum of six intersections with each other. What is the maximum number of intersections that a hundred circles could have?
Sets of integers like 3, 4, 5 are called Pythagorean Triples, because they could be the lengths of the sides of a right-angled triangle. Can you find any more?
Show that for any triangle it is always possible to construct 3 touching circles with centres at the vertices. Is it possible to construct touching circles centred at the vertices of any polygon?
It's easy to work out the areas of most squares that we meet, but what if they were tilted?
Spotting patterns can be an important first step - explaining why it is appropriate to generalise is the next step, and often the most interesting and important.
Can you dissect a square into: 4, 7, 10, 13... other squares? 6, 9, 12, 15... other squares? 8, 11, 14... other squares?
What is the volume of the solid formed by rotating this right angled triangle about the hypotenuse?
The diagram shows a 5 by 5 geoboard with 25 pins set out in a square array. Squares are made by stretching rubber bands round specific pins. What is the total number of squares that can be made on a. . . .
The opposite vertices of a square have coordinates (a,b) and (c,d). What are the coordinates of the other vertices?
A 2 by 3 rectangle contains 8 squares and a 3 by 4 rectangle contains 20 squares. What size rectangle(s) contain(s) exactly 100 squares? Can you find them all?
What would be the smallest number of moves needed to move a Knight from a chess set from one corner to the opposite corner of a 99 by 99 square board?
Triangular numbers can be represented by a triangular array of squares. What do you notice about the sum of identical triangle numbers?
Imagine a large cube made from small red cubes being dropped into a pot of yellow paint. How many of the small cubes will have yellow paint on their faces?
What are the areas of these triangles? What do you notice? Can you generalise to other "families" of triangles?
How many moves does it take to swap over some red and blue frogs? Do you have a method?
Square numbers can be represented as the sum of consecutive odd numbers. What is the sum of 1 + 3 + ..... + 149 + 151 + 153?
If you can copy a network without lifting your pen off the paper and without drawing any line twice, then it is traversable. Decide which of these diagrams are traversable.
Euler discussed whether or not it was possible to stroll around Koenigsberg crossing each of its seven bridges exactly once. Experiment with different numbers of islands and bridges.
Try entering different sets of numbers in the number pyramids. How does the total at the top change?
An article for teachers and pupils that encourages you to look at the mathematical properties of similar games.
This article for teachers describes several games, found on the site, all of which have a related structure that can be used to develop the skills of strategic planning.
Find some examples of pairs of numbers such that their sum is a factor of their product. eg. 4 + 12 = 16 and 4 × 12 = 48 and 16 is a factor of 48.
Triangle ABC is an equilateral triangle with three parallel lines going through the vertices. Calculate the length of the sides of the triangle if the perpendicular distances between the parallel. . . .
Take any two positive numbers. Calculate the arithmetic and geometric means. Repeat the calculations to generate a sequence of arithmetic means and geometric means. Make a note of what happens to the. . . .
Can you use the diagram to prove the AM-GM inequality?
Imagine we have four bags containing numbers from a sequence. What numbers can we make now?
Can you describe this route to infinity? Where will the arrows take you next?
It starts quite simple but great opportunities for number discoveries and patterns!
The sum of the numbers 4 and 1 [1/3] is the same as the product of 4 and 1 [1/3]; that is to say 4 + 1 [1/3] = 4 × 1 [1/3]. What other numbers have the sum equal to the product and can this be so for. . . .
Consider all two digit numbers (10, 11, . . . ,99). In writing down all these numbers, which digits occur least often, and which occur most often ? What about three digit numbers, four digit numbers. . . .
Charlie has made a Magic V. Can you use his example to make some more? And how about Magic Ls, Ns and Ws?
What would you get if you continued this sequence of fraction sums? 1/2 + 2/1 = 2/3 + 3/2 = 3/4 + 4/3 =
A game for 2 players
A game for two people, or play online. Given a target number, say 23, and a range of numbers to choose from, say 1-4, players take it in turns to add to the running total to hit their target.
The aim of the game is to slide the green square from the top right hand corner to the bottom left hand corner in the least number of moves.
What size square corners should be cut from a square piece of paper to make a box with the largest possible volume?
Imagine you have a large supply of 3kg and 8kg weights. How many of each weight would you need for the average (mean) of the weights to be 6kg? What other averages could you have?
Do you notice anything about the solutions when you add and/or subtract consecutive negative numbers?
Can all unit fractions be written as the sum of two unit fractions?
The Egyptians expressed all fractions as the sum of different unit fractions. Here is a chance to explore how they could have written different fractions.
Jo made a cube from some smaller cubes, painted some of the faces of the large cube, and then took it apart again. 45 small cubes had no paint on them at all. How many small cubes did Jo use?
Can you find an efficient method to work out how many handshakes there would be if hundreds of people met?
Use the animation to help you work out how many lines are needed to draw mystic roses of different sizes.
A country has decided to have just two different coins, 3z and 5z coins. Which totals can be made? Is there a largest total that cannot be made? How do you know?
We can show that (x + 1)² = x² + 2x + 1 by considering the area of an (x + 1) by (x + 1) square. Show in a similar way that (x + 2)² = x² + 4x + 4
Imagine starting with one yellow cube and covering it all over with a single layer of red cubes, and then covering that cube with a layer of blue cubes. How many red and blue cubes would you need? | <urn:uuid:9b3387da-1ebf-4238-83de-75ae61546ef9> | 3.75 | 1,610 | Content Listing | Science & Tech. | 75.18778 | 95,599,572 |
Characterisation of the structure of graphene
Graphene, the world's first two-dimensional material, is many times stronger than steel, more conductive than copper, lightweight, flexible and one million times thinner than a human hair.
Graphene is set to improve the quality of life for many across the globe. Potential applications include inexpensive water purification systems; greener, more efficient cars and planes; flexible phones and even biomedical applications such as wound healing and cancer treatments.
Graphene's commercial adoption will be accelerated by answering two key questions: 'What are the characteristics of commercially-supplied graphene' and 'how can they be used to best effect'. The establishment of common industrial metrics, regarding for example the number of layers or flake size, is crucial for the uptake of graphene-based technologies.
The National Graphene Institute at the University have partnered with NPL to produce a guide, as part of NPL's good practice guide series, that aims to tackle the ambiguity surrounding how to measure graphene's characteristics.
Titled "Characterisation of the Structure of Graphene," the guide provides producers and users of graphene with an understanding of how to reliably measure the structural properties of graphene.
Material standardisation is crucial for industry uptake. There are many early adopters of graphene but without standardisation it is difficult for industry to be assured of the quality and properties of its graphene samples.
This guide seeks to address this gap and brings together the accepted measurement techniques in this area. It describes the high-accuracy and precision required for verification of material properties and will enable the development of other faster quality control techniques in the future.
Intended to form a bedrock for future interlaboratory comparisons and international standards, the guide will accelerate the development of graphene-enabled technology and improve the ability to produce graphene in a reliable and repeatable way.
Dr Andrew Pollard, lead author of the guide and Senior Research Scientist at NPL, commented: "Although there are many ways to measure the properties of different types of commercially-available 'graphene', industry needs a standardised set of measurements. This will enable companies to select the type of material best suited to their needs by reliably comparing key characteristics, supporting the development of innovative new technologies based on graphene. This guide is the first step in this process, and as the basis of international measurement standards currently being developed, will provide measurement protocols that can be used in the interim."
James Baker, Graphene Business Director at The University of Manchester said: "This good practice guide has been developed by the NGI and NPL teams to allow the nascent graphene industry to perform accurate, reproducible and comparable measurements of commercially supplied graphene. This will address this important commercialisation barrier by providing users with a consistent approach to the structural characterisation of graphene whilst international measurement standards are being developed".
More information: The guide is available online: www.npl.co.uk/publications/gui … ructure-of-graphene/
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Optimize unaligned reading #42
Unaligned reading is performed using a pair of LWL and LWR, usually they are not contiguous if the compiler tries to use other registers to improve speed.
The way you read an unaligned word is like this:
lwl RT, offset(RS)
Currently the implementation of LWL and LWR is slow, so it would be great if we try to find both instructions and convert it in a single unaligned read word.
In order to be able to perform this optimization safely we have to see that we don't have any jump label between those instructions, and there is no access to RS or RT registers in the instructions between.
Then we replace the LWL with the load, and tell the compiler to ignore the LWR instruction. | <urn:uuid:e04ea25c-2557-45dc-a1ce-f826f509940d> | 2.625 | 195 | News (Org.) | Software Dev. | 45.100306 | 95,599,653 |
Lawrence Livermore National Laboratory researchers are making key contributions to a physics experiment that will look for one of nature's most elusive particles, "dark matter," using a tank nearly a mile underground beneath the Black Hills of South Dakota.
The Large Underground Xenon (LUX) experiment located at the Sanford Underground Research Facility in Lead, S.D. is the most sensitive detector of its kind to look for dark matter. Thought to comprise more than 80 percent of the mass of the universe, scientists believe dark matter could hold the key to answering some of the most challenging questions facing physicists in the 21st century. So far, however, dark matter has eluded direct detection.
LLNL researchers have been involved in the LUX experiment since 2008.
"We at LLNL initially got involved in LUX because of the natural technological overlap with our own nonproliferation detector development programs," said Adam Bernstein, who leads the Advanced Detectors Group in LLNL's Physics Division.
|Shown is a side view of the Lawrence Livermore National Laboratory-designed and built copper photomultiplier tube mounting structure, which is a key component of the Large Underground Xenon (LUX) detector, located at the Sanford Underground Research Facility in Lead, S.D. Photo courtesy of Lawrence Livermore National Laboratory|
"It's very exciting to reflect that as a result, we are now part of a world-class team that stands an excellent chance of being the first to directly and unambiguously measure cosmological dark matter particle interactions in an earthly detector."
The cutting-edge science and technology of rare event detection represented by LUX is of direct interest for LLNL and U.S. nonproliferation, arms control and nuclear security missions, Bernstein noted.
In particular, cryogenic noble liquid detectors of this kind may allow for improved, smaller footprint reactor antineutrino monitoring systems, with application to the International Atomic Energy Agency reactor safeguards regime.
Xenon and argon detectors of very similar design also have excellent neutron and gamma ray detection and discrimination properties, and may assist with missions related to the timely discovery and characterization of fissile materials in arms control and search contexts.
LLNL scientists and technicians have made important contributions to LUX.
Lab staff physicist Peter Sorensen has directed the LUX Analysis Working Group, spent months at the site helping to install the detector and has written numerous peer-reviewed articles on how to perform searches for a range of dark matter candidates using LUX and related detectors.
Fellow LLNL staff physicist Kareem Kazkaz is the author of the LUX detector simulation package, known as LUXSIM, and has directed the Simulations Working Group for the project. The simulation software embodied in LUXSIM is uniquely well suited for low background detectors of this kind, and has been picked up by other users in the dark matter and nonproliferation communities.
|Shown is a top-down view of the Lawrence Livermore National Laboratory-designed and built copper photomultiplier tube mounting structure, which is a key component of the LUX detector. Photo courtesy of Lawrence Livermore National Laboratory|
LLNL technicians John Bower and Dennis Carr (who is now retired) both played key roles in the manufacture and installation of elements of the LUX detector, including building the precision-machined copper photo multiplier tube mounting apparatus. Lab safety engineer Gerry Mok performed detailed calculations demonstrating the safety of the LUX pressurized and cryogenic systems under a range of possible accident scenarios. His work was important to the successful safety review of the LUX detector.
The Sanford Underground Research Facility (Sanford Lab), located in the former Homestake gold mine, is owned and operated by the South Dakota Science and Technology Authority, with support from the Department of Energy and the DOE's Lawrence Berkeley National Laboratory. The LUX scientific collaboration includes dozens of scientists at 17 research universities and national laboratories in the United States and Europe.
The LUX detector took more than three years to build in a surface facility at the Sanford Lab. In July, a team of researchers, engineers and technicians installed the detector in an excavated cavern 4,850 feet underground. Nearly a mile of solid rock will protect the sensitive experiment from the shower of cosmic radiation that constantly bombards the surface of the earth. Cosmic radiation would drown out faint dark matter signals if the detector were on the surface.
LUX also must be protected from the small amounts of natural radiation from the surrounding rock. That's why the detector, which would just fit inside a telephone booth, was lowered into a very large stainless steel tank -- 20 feet tall by 24 feet in diameter. That tank has now been filled with more than 70,000 gallons of ultra-pure de-ionized water that will shield the detector from gamma radiation and stray neutrons.
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Edited By: RM Harrison
Understanding pollution, its behaviour and impact is becoming increasingly important, as new technologies and legislation continually lower the tolerable levels of pollutants released into the environment. Introduction to Pollution Science draws upon sections of the authors' previous text Understanding our Environment and reflects the growing trend of a more sophisticated approach to teaching environmental science at university. This new revised book discusses the basics of environmental pollution drawing upon chemistry, physics and biological sciences.
The book, written by leading experts in the field, covers topics including pollution in the atmosphere, the world's waters and soil and land contamination. Subsequent sections discuss methods of investigating the environment, the impact of pollution on human health and ecological systems, and institutional mechanisms for pollution management. Each section includes worked examples and questions and is aimed at undergraduates studying environmental science, but will also be useful for others seeking knowledge of the field.
This is an interesting and highly informative book. The chapters on water, soil and sludge contamination and environmental management deserve special mention. -- Chemistry & Industry, 27 August 2007 (Prabhu Kulkarni) Chemistry and Industry Suited to students on degree courses in environmental science and pollution studies at both undergraduate and taught postgraduate levels. Its wider pollution-oriented content will also be of value to chemistry students. Some chapters, such as those on the atmosphere, investigating the environment and ecological and health effects of chemical pollution, have been modified and updated. Others, such as the chapters on the world's waters, which replaces separate chapters on the oceans and freshwater, and soils and land contamination, have been written by new authors. Each chapter contains case studies anad is now extensively referenced. -- Education in Chemistry, September 2007, 159 (Hugh Flowers) Education in Chemistry
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Global Carbon Dioxide Emissions Have Now Been Flat for Two Years Running
The International Energy Agency says emissions growth has decoupled from global economic growth.
New data published by the International Energy Agency extends the surprising finding, discovered last year, that global carbon dioxide emissions have stopped growing despite continued economic growth. The latest data show the trend has continued for a second consecutive year, which the IEA says is a result of renewable energy accounting for 90 percent of new electricity generation in 2015. China’s slowing economic growth has played a key role in these figures as well, though, and with India and several other developing economies set to grow substantially over the next several years, it’s not clear how long we can expect this “decoupling” trend to continue.
The IEA and the Global Carbon Project, an international group of climate researchers, have now independently concluded that China’s emissions appear to have declined in 2015. This reflects a substantial drop in coal use that corresponds with a slowdown in construction, but also with actions taken by the Chinese government to curb coal consumption for the sake of reducing air pollution. China has pledged that its emissions will peak by 2030, but it could be that we have already seen the peak more than a decade early.
As China’s economy slows, however, India’s is just now ramping up, and economists project that several other large developing nations will grow very rapidly over the next decade. What that means for emissions growth will depend on how those countries choose to meet their rising demand for energy.
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American pikas, the chirpy, potato-sized denizens of rocky debris in mountain ranges and high plateaus in western North America, are holding their own in the Southern Rocky Mountains, says a new University of Colorado Boulder study.
American pikas are holding their own in the Southern Rocky Mountains, says new CU-Boulder study. Credit: Peter Erb
Led by CU-Boulder doctoral student Liesl Erb, the study team assessed 69 historical sites known to host pikas in a swath of the Southern Rockies ranging from southern Wyoming through Colorado and into northern New Mexico. The results showed that 65 of the 69 historical sites that had hosted pikas -- some dating back more than a century -- were still occupied by the round-eared, hamster-like mammals, Erb said.
The new study stands in contrast to a 2011 study in Nevada's Great Basin that showed local extinction rates of pika populations there have increased nearly five-fold in the past decade. That study, by a separate research group, also showed that local Great Basin pika populations had moved up in elevation nearly 500 feet in the past 10 years, a migration believed to be triggered by warming temperatures.
Despite the low number of extirpations, or local population extinctions, in the Southern Rockies, the CU-Boulder team found that the pattern of pika disappearance at particular sites was not random, said Erb of the ecology and evolutionary biology department and lead study author. "The sites that had been abandoned by pikas in our study area all were drier on average than the occupied sites," she said.
A paper on the new CU-Boulder study by Erb is being published in the September issue of the journal Ecology. Co-authors include CU-Boulder Research Associate Chris Ray and Associate Professor Robert Guralnick, both affiliated with the ecology and evolutionary biology department.
The study was funded primarily by the National Geographic Society.
One likely reason for the relative success of pikas in the Southern Rocky Mountains study is that available habitats are higher in elevation and are more contiguous than habitats in Nevada's Great Basin, said Erb. But some climate models are predicting drier conditions in parts of the Southern Rockies in the coming decades as the climate warms, she said.
Alpine species are among the plants and animals most threatened by climatic shifts because of their physiological and geographic constraints, said Erb. In 2010, the U.S. government denied endangered species listing for the American pika in part because there was insufficient data on its distribution and abundance across western North America. The American pika lives in mountainous regions including British Columbia, Washington, Oregon, Idaho, Montana, Utah, Wyoming, Colorado, Nevada, California and New Mexico.
Surprisingly, most of the pikas that have disappeared from Great Basin sites under study in recent years were from sites that experienced extremely cold temperatures and may be related to a lack of winter snowpack insulation, said Ray, who has participated in several Great Basin pika studies including the 2011 study. Ray suspects pikas may reduce summer foraging activities to avoid heat stress caused by rising temperatures, leading to smaller winter food caches that can't sustain them during extreme cold snaps.
Guralnick, also curator of invertebrate zoology for the University of Colorado Museum of Natural History, said pikas are becoming a "bellwether" species for mountain ecosystems, primarily due to their recent Great Basin declines. Prior to the new CU survey, population trends of pikas in the Rockies were relatively unknown, he said.
"Many have assumed that warming temperatures would be the primary signal affecting North American pikas," said Guralnick. "This study shows it is more complicated than that, and that drier conditions could affect the persistence of pikas across the West."
The CU-Boulder study team initially looked at about 800 historical records of pika sightings in Colorado, New Mexico and Wyoming, but most locations were not specific enough for scientific use. The team eventually narrowed down the historical sites of pikas to 69 specific places known to have been occupied at some point before 1980, using tools like GPS to help pinpoint the geographical accuracy of each individual site.
Members of the rabbit family, the conspicuous pikas can be seen scurrying about rocky debris known as talus in alpine and subalpine regions of the Rockies, emitting their signature, high-pitched squeaks. Instead of hibernating, pikas cache huge amounts of plants and flowers known as hay piles under large rocks that sustain them through the long winters.
The CU team used data from Oregon State University's PRISM Climate Group to compile local climate information from 1908 to 2007 for the 69 historical pika sites in the Southern Rockies. The information produced estimates of monthly precipitation and minimum and maximum temperatures. The team confirmed the presence of pikas at each site either visually, by their distinctive squeaks, or by evidence of fresh pika hay piles cached under rocks in the study areas.
Sites visited early in the 2008 field season that lacked fresh pika signs were revisited in late October and early November for re-evaluation, Erb said. In places where pikas were still absent, researchers searched rock slopes up to two miles in all directions in an attempt to locate pika populations.
Volunteers have helped gather similar data on pikas through the PikaNET program, the Front Range Pika Project and the New Mexico Pika Monitoring Project. Such volunteer projects are organized through collaborations between CU-Boulder, the Colorado Division of Wildlife, the Denver Zoo, Rocky Mountain Wild, Colorado State University, the Mountain Studies Institute in Silverton, Colo., the San Juan Public Lands Center headquartered in Durango, Colo., and the Seventh Generation Institute in Santa Fe, N.M.
"It is good news that pikas are doing better in the Southern Rocky Mountains than some other places," said Erb. "It is likely that the geographic traits of the Rockies are a big reason why we are not seeing significant declines, at least not yet."
Editors: A video news story will be available at http://www.colorado.edu/news/ following the embargo lift on Sept. 1. A still image of an American pika is available at http://photography.colorado.edu/netpub/server.np?find&site=news&catalog=catalog&template=detail.np&field=itemid&op=matches&value=3572.Contact:
Liesl Erb | EurekAlert!
Upcycling of PET Bottles: New Ideas for Resource Cycles in Germany
25.06.2018 | Fraunhofer-Institut für Betriebsfestigkeit und Systemzuverlässigkeit LBF
Dry landscapes can increase disease transmission
20.06.2018 | Forschungsverbund Berlin e.V.
A new manufacturing technique uses a process similar to newspaper printing to form smoother and more flexible metals for making ultrafast electronic devices.
The low-cost process, developed by Purdue University researchers, combines tools already used in industry for manufacturing metals on a large scale, but uses...
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
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Citric Acid Cycle The citric acid cycle starts with the combination of acetyl-CoA (2C) and oxaloactate (4C) to generate citrate (6C). Through a series of eight reactions, two CO2 molecules are released, and oxaloacetate is regenerated. The citric acid cycle does not directly generate much energy. Each turn of the cycle generates one ATP via substrate-level phosphorylation and a GTP intermediate, for a total of two pyruvates per glucose molecule. The value of the citric acid cycle is its ability to generate high-energy electrons that are carried by NADH and FADH2. For each molecule of acetyl-CoA that enters the cycle, three NADH and one FADH2 are produced by two to account for the fact that the cycle turns twice per molecule of glucose. These enzymes then transport the electrons to the electron transport chain on the inner mitochondrial membrane, where more ATP is produced via oxidative phosphorylation. At the end of the citric acid cycle, oxaloacetate is regenerated in anticipation of the next round.
Glycolysis Video: https:///watch?v=hDq1rhUkV-g
∑ - In aerobic cell respiration pyruvate is decarboxylated and oxidized, and converted into acetyl compound and attached to coenzyme A to form acetyl coenzyme A in the link reaction.
Decarboxylation is a chemical reaction that removes a carboxyl group and releases carbon dioxide (CO2).
Oxidation is the loss of electrons or an increase in oxidation state by a molecule, atom, or ion. Pyruvate is oxidized by the by the removal of pairs of hydrogen atoms (with their electrons), which are passed on the NAD+ and FAD | <urn:uuid:adfb79e1-c4b3-4419-be67-92765badb6c6> | 3.328125 | 386 | Knowledge Article | Science & Tech. | 27.031795 | 95,599,697 |
Time-resolved “stop-action” measurements and advanced theoretical simulations identify an unusual form of energy loss
Understanding the properties of complex quantum materials is a major goal of condensed matter physics and materials science, since effects like high-temperature superconductivity might lead to a broad range of applications.
Now an international team of scientists including Emmy Noether group leader Michael Sentef from the Max Planck Institute for the Structure and Dynamics of Matter at CFEL in Hamburg has demonstrated a new laser-driven “stop-action” technique for studying complex electron interactions under dynamic conditions. The findings, published in the journal Nature Communications today, are expected to improve the understanding of the physical processes leading to emergent phenomena in strongly correlated materials.
Scientists studying high temperature superconductors—materials that carry electric current with no energy loss when cooled below a certain temperature—have been searching for ways to study in detail the electron interactions thought to drive this promising property. One big challenge is disentangling the many different types of interactions—for example, separating the effects of electrons interacting with one another from those caused by their interactions with the atoms of the material.
In the present study, the researchers used one very fast, intense “pump” laser to give electrons a blast of energy, and a second “probe” laser to measure the electrons’ energy level and direction of movement as they relax back to their normal state.
“By varying the time between the ‘pump’ and the ‘probe’ laser pulses we can build up a stroboscopic record of what happens—a movie of what this material looks like from rest through the violent interaction to how it settles back down,” said Jonathan Rameau, physicist at the Brookhaven National Laboratory and one of the lead authors on the paper. “It’s like dropping a bowling ball in a bucket of water to cause a big disruption, and then taking pictures at various times afterward,” he explained.
The technique, known as time-resolved, angle-resolved photoelectron spectroscopy (tr-ARPES), combined with complex theoretical simulations and analysis, allowed the team to tease out the sequence and energy “signatures” of different types of electron interactions. They were able to pick out distinct signals of interactions among excited electrons (which happen quickly, but don’t dissipate much energy), as well as later-stage random interactions between electrons and the atoms that make up the crystal lattice (which generate friction and lead to gradual energy loss in the form of heat).
But they also discovered another, unexpected signal—which they say represents a distinct form of extremely efficient energy loss—at a particular energy level and timescale between the other two.
“We see a very strong and peculiar interaction between the excited electrons and the lattice, where the electrons are losing most of their energy very rapidly in a coherent, non-random way,” Rameau said. At this special energy level, he explained, the electrons appear to be interacting with lattice atoms all vibrating at a particular frequency—like a tuning fork emitting a single note.
When all of the electrons that have the energy required for this unique interaction have given up most of their energy, they start to cool down more slowly by hitting atoms more randomly without striking the resonant frequency, he said. The resonance frequency of this process is particularly noteworthy, the scientists say, because its energy level corresponds with a “kink” in the energy signature of the same material studied previously in its superconducting state using a static form of ARPES.
At that time, scientists suspected the kink might have something to do with the material’s ability to become a superconductor. They couldn’t detect the same signal above the superconducting temperature. But the new time-resolved experiments, which were done on the material well above its superconducting temperature, were able to tease out the subtle signal. These new findings indicate that this special condition exists even when the material is not a superconductor. “We know now that this interaction doesn’t just switch on when the material becomes a superconductor; it’s actually always there,” Rameau said.
Michael Sentef, who complemented the experimental work with numerical simulations, stressed the impact of this work for the field of pump-probe spectroscopy. “This work highlights the fact that we have advanced our theoretical understanding of systems far from thermal equilibrium to the point where we can make quantitative predictions for experiments,” he said. “This insight is very motivating for future work addressing even more complex situations, in which laser pulses are used to induce high-temperature superconducting-like states,” Sentef added. In a recent work [Mitrano et al., Nature 530, 461–464 (2016)], a team around Andrea Cavalleri from the MPSD at CFEL in Hamburg observed light-induced superconducting-like properties in the material K3C60.
Dr. Michael A. Sentef
Max Planck Institute for the Structure and Dynamics of Matter
Center for Free-Electron Laser Science
Luruper Chaussee 149
+49 (0)40 8998-6552
J. D. Rameau, S. Freutel, A. F. Kemper, M. A. Sentef, J. K. Freericks, I. Avigo, M. Ligges, L. Rettig, Y. Yoshida, H. Eisaki, J. Schneeloch, R. D. Zhong, Z. J. Xu, G. D. Gu, P. D. Johnson, and U. Bovensiepen, "Energy Dissipation from a Correlated System Driven Out of Equilibrium," Nature Communications (2016), DOI: 10.1038/ncomms13761
http://dx.doi.org/10.1038/ncomms13761 Original publication
http://dx.doi.org/10.1038/nature16522 Mitrano et al., Nature 530, 461–464 (2016)
http://www.mpsd.mpg.de/en/research/theo Research group of Prof. Angel Rubio
http://www.mpsd.mpg.de/en Max Planck Institute for the Structure and Dynamics of Matter
Dr. Michael Grefe | Max-Planck-Institut für Struktur und Dynamik der Materie
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....
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Radiocarbon dating reference year
Check here for important announcements and other Shroud of Turin Website news.
According to evolutionists, the diamonds formed about 1–3 billion years ago.
When objects of the Old Kingdom and Middle Kingdom of Egypt yielded carbon dates that appeared roughly comparable with the historical dates, Libby made his method known.
With initial large margin of error and anything that did not square with expectation, judged as contaminated, the method appeared to work and was hailed as completely reliablejust as the atomic clock is reliableand this nobody doubted.
Each item carries a posting date indicating when it first went online.
The most recent update appears at the top of the page.
The abbreviation "BP", with the same meaning, has also been interpreted both of which requested that publications should use the unit "a" for year and reserve the term "BP" for radiocarbon estimations. A large quantity of contemporary oxalic acid dihydrate was prepared as NBS Standard Reference Material (SRM) 4990B. This value is defined as "modern carbon" referenced to AD 1950. | <urn:uuid:1fb3978e-d129-424e-925e-e69c0c950079> | 3.28125 | 227 | Knowledge Article | Science & Tech. | 34.33546 | 95,599,712 |
NEW ORLEANS – Hurricane Harvey’s historic deluge in Texas showed clear signs of human-caused climate change, with rainfall at least 15 percent heavier and the likelihood of such a calamity tripled, according to two independent studies published Wednesday. The new findings are part of a surge of research suggesting that communities need to revisit their vulnerability to extreme weather in a warming world.
“Climate change made this event more likely and heavier,” said Karin van der Wiel, a researcher at the Royal Netherlands Meteorological Institute who co-wrote one of the papers and is among 25,000 people attending the fall meeting of the American Geophysical Union here.
Hurricane Harvey hit the Texas coast near Corpus Christi on Aug. 25 after it intensified rapidly in the Gulf of Mexico. The storm then stalled, as if plugged in mud, and dropped record rains for the better part of a week on Southeast Texas before finally drifting north and dissipating. The storm flooded Houston and much of the region and was one of several hurricanes that impacted the United States during a volatile 2017 season, including Hurricane Irma in Florida and Hurricane Maria in Puerto Rico.
Van der Wiel and her colleagues concluded that a deluge such as Harvey would have occurred in the region once every 2,400 years in the pre-warming period but that it is now a 1-in-800 year event - and is becoming more likely. Her research found that warming likely increased the intensity of the storm’s precipitation by approximately 15 percent.
The second study, from researchers based at the Lawrence Berkeley National Laboratory, said Harvey’s precipitation was likely boosted by at least 19 percent. And that’s just the lower bound; the team’s best estimate, which acknowledges a great deal of uncertainty, is a 38 percent increase. The report found the likelihood of a Harvey-like event had probably increased tenfold but at the very least had tripled.
“Thirty-eight percent seems pretty big,” Columbia University research professor Suzana Camargo, an expert on extreme weather, said when she looked over a poster outlining the research of Michael Wehner, senior staff scientist at the national laboratory in Berkeley. She said this kind of research points to the inadequacy of today’s flood maps, which need updating as the climate changes: “They have not been improving the maps as they should. They’re treating that as static.”
The AGU meeting is a sprawling affair in a convention center that extends for what seems like a full mile along the Mississippi River. The annual meeting is a scientific wonderland, with experts on hurricanes, earthquakes, volcanoes, climate change, Mars, Jupiter - you name it.
The meeting has numerous sessions Wednesday devoted to late-breaking research on hurricanes Harvey, Irma and Maria. Scientific research usually takes longer to cohere, but 2017 was an astonishing year of natural disasters and many people dropped what they were doing to tease out early findings about the hurricanes and other tumult, including western U.S. wildfires.
The Dutch and Berkeley research teams worked independently and used different methods - for example, examining different geographical areas, different time periods during the week that Harvey struck Texas, and framing their findings with different standards of certainty. Though their numbers are not identical, the scientists on the two teams emphasized that each study bolsters the other, with strikingly similar conclusions and lessons for the future.
“We have two independent efforts with essentially the same answer,” said Wehner. “There’s a clear human fingerprint. The numbers will undoubtedly change as more researchers look at this with different techniques, and perhaps different data sets and different methods. But our numbers are kind of big.”
He added: “We were stunned.”
“Attribution” research, as it’s known, seeks to find a climate change signal amid a weather event, which has always been problematic. There’s a truism: Climate is what you expect and weather is what you get. Weather events emerge from chaotic forces and elements, and there is variability from place to place and year to year. Scientists, and journalists reporting on weather, have typically framed their reports with caveats and cautionary notes, relying on the generalization that climate change makes events more likely but doesn’t necessarily cause them.
“There is a large, new body of literature about attributing human influence on individual extreme events,” Wehner said. “It’s no longer appropriate to say scientists can’t say anything about these individual events.”
The textbooks declare that for every degree Celsius increase in atmospheric temperature there should be 6 to 8 percent more moisture in the air. That’s roughly the degree of global atmospheric warming in the past century. Wehner said he guessed, when he started his research, that Harvey might have dropped about 6 to 8 percent more rain than an identical storm would have dropped in 1950. But both the Dutch and Berkeley teams found the actual rainfall to be much higher than expected.
Van der Wiel said that indicates that there is some factor, perhaps involving the dynamics of hurricanes, that results in additional precipitation - beyond what you’d expect for the greater atmospheric moisture. As she put it, “There’s another extra thing on top of it.”
This is not the first time scientists have said an extreme weather event has a signal of climate change. Wehner said the 2010 Texas drought was an event twice as likely due to climate change. And floods in September 2013 in Colorado came after rainfall that was 30 percent heavier that should be expected, he said.
“In 2017, climate change slammed the U.S. hard,” he said. “But it’s not the first time it’s happened.” | <urn:uuid:c2f5e07d-35a9-4c7f-9949-c2c047882ce7> | 2.96875 | 1,200 | News Article | Science & Tech. | 41.780473 | 95,599,717 |
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Sea ice extent in the Arctic region continues to run close to the 1979-2000 year average at this time. Thin, one-year ice continues to remain entrenched across a large part of the Bering Sea thanks in part to the bitterly cold winter and favorable winds into the early Spring.
However, just because the sea ice extent is running near normal at this time does not mean in any way that we are on the start of a long term recovery of Arctic sea ice. The situation is still rather bleak.
Image courtesy of the National Snow and Ice Data Center.
I am certainly no expert when it comes to the behavior of sea ice, but I suspect that we will see a significant decrease (greater decline than normal) during the month of May since there is a very high percentage of ice that is thin and will melt out quickly as temperatures continue to warm into early summer.
Latest MODIS high resolution image of Hudson Bay, Canada from earlier today shows most of the bay still covered with ice, which is normal for this time of year.
Arctic sea ice volume shows the true picture
The latest estimated Arctic sea ice volume, which takes into account both the extent and thickness of the ice, shows that 2012 is running right in line with the record low volume year of 2011. Image courtesy of the Polar Science Center at the University of Washington.
Comments that don't add to the conversation may be automatically or manually removed by Facebook or AccuWeather. Profanity, personal attacks, and spam will not be tolerated.
Data indicates that there has been a slight downward trend in the annual maximum extent of Great Lakes ice cover since the 1970s.
A new study concludes that global warming may eventually be twice as warm as what current climate model consensus indicates.
The increased use of air conditioning in a warming world may lead to a significant degradation of air quality in the eastern U.S. by mid-century.
Dr. James Hansen's climate model projections from the 1980s have been mostly on target.
May 2018 and the spring of 2018 both ranked in the top five warmest on record.
Rate of ice loss in Antarctica has tripled over the past decade.
A combination of a warming climate climate and increased urbanization (heat island effect) has caused a 25 to 50 percent decrease in low cloud cover in the greater Los Angeles area since the 1970s. | <urn:uuid:5369e7bf-4a6f-4a38-91b4-e6a255e3ad7e> | 3.125 | 486 | News Article | Science & Tech. | 49.438686 | 95,599,718 |
posted by need help
write each of the following as the ratio of two integers in lowest terms:
2 and 3/4
Any integer n can be written as n/1. If the ratio of two integers is in lowest terms then the greatest common divisor or gcd of them is 1. What is the gcd of 3 and 4? | <urn:uuid:c627d0a7-1ebf-40f6-a5c0-114d34b7e013> | 3.265625 | 73 | Q&A Forum | Science & Tech. | 89.245 | 95,599,721 |
Skip to comments.Climate alarmists lose another piece of evidence
Posted on 06/11/2007 10:11:38 AM PDT by Neville72
Don't look now, but another big chunk of the "evidence" for man-made global warming suddenly disappeared. Poof! Researchers just reported that the world's most recent case of "abrupt climate change"which occurred a mere 12,000 years agowas probably due to a comet strike, not to "climate sensitivity."
The Younger Dryas occurred as an Ice Age was ending. As the climate began to warm, a huge and sudden rush of fresh meltwater broke out from the Great Lakes and swept out to sea. The water surge was monumental enough that the meltwater lowered the salinity of the ocean, shut down the Atlantic conveyor currents, which disperse the planet's heat, and threw the northern hemisphere back into another thousand years of Ice Age. It raised temperatures near Greenland by a startling 15 degrees C, even as it doubled annual rainfall.
Modern climatologists have savored the Younger Dryas event as massive evidence of what comes when we push the planet's climate too close to a "tipping point." Further human-driven warming, they say, will make such abrupt climate changes more likely, with searing droughts, torrential rainfall, and extreme heat.
The National Academy of Sciences issued a 2002 report titled Abrupt Climate Change: Inevitable Surprises, which said abrupt climate changes have been especially common when the climate system was being forced to change most rapidly. According to that theory, greenhouse warming today could be drastically increasing risks from climate change.
At least, that's what the experts said until the latest meeting of the American Geophysical Union in Acapulco on May 23rd when James Kennett of the University of California/Santa Barbara presented evidence of a dramatically different cause for the Younger Dryas event: a comet that struck somewhere near the Great Lakes.
"Highest concentrations of extraterrestrial impact materials occur in the Great Lakes area and spread out from there," Kennett says. "It would have had major effects on humans. Immediate effects would have been in the North and East, producing shockwaves, heat, flooding, wildfires, and a destruction and fragmentation of the human population."
Paleontologists had assumed a huge lake of meltwater accumulated near the Great Lakes due to the Ice Age ending, but had never located its possible site. Nor have they explained a thin layer of charred sediment found throughout North America that dates from 12,000 years ago. The sediment layer contains carbon spheres whose creation would have required temperatures of at least 4000 C. Electron microscopes reveal that the carbon beads contain tiny diamonds whose creation would have required enormous temperatures and pressures.
The U.S. sediment layer does not contain much iridium, which is the telltale signal of an asteroid strike. That argues for a comet, made up primarily of "dirty ice," rather than an asteroid like the one which hit Mexico's Yucatan Peninsula 65 million years ago and wiped out the dinosaurs.
Kennett says the ice sheet could have absorbed the impact of the comet's "dirty ice," even as the comet's heat produced the flood of meltwater. Kennett says the comet may have destroyed 15 mammal species and might have left only a few surviving humans from North America's early Clovis culture. America's bison survived, but much smaller in size and with a remarkable similarity in their DNAindicating that they descended from a small group of comet survivors.
The comet theory comes as a crushing blow to the climate alarmists. It follows the publication of Unstoppable Global WarmingEvery 1,500 Years, which assembles the historic and scientific evidence of a long, natural climate cycle that swings temperatures about 2-4 degrees C over its lifetimeaccounting for the Medieval Warming, the Roman Warming and the Holocene Warming 5,000 years ago. Then came Henrik Svensmark's demonstration at the Danish Space Research Institute, of how cosmic rays link changes in the sun's irradiance to the formation of the low, wet clouds that cover more than 20 percent of the earth. The clouds are nature's thermostats, deflecting more or less heat back out to space depending on the sun's strength.
Now the alarmists have lost the "abrupt climate change" of the Younger Dryas. More and more, recent science is pointing to our modern warming as being part of a 1500-year cycle that stretches back at least a million years.
If the Younger Dryas was caused by a comet, perhaps we should rethink being frightened by the neighbor's SUV.
Dennis T. Avery was a senior policy analyst for the U.S. State Department, where he won the National Intelligence Medal of Achievement. He is the co-author, with atmospheric physicist Fred Singer, of the book, Unstoppable Global WarmingEvery 1500 Years, available from Rowman & Littlefield. Readers may write him at the Center for Global Food Issues, Post Office Box 202, Churchville, VA 24421
If the Younger Dryas was caused by a comet, perhaps we should rethink being frightened by the neighbor's SUV.Oh, yee of little faith!
Are you too blind to see that maybe, just maybe, that comet was CAUSED by the neighbor's SUV?
(None are so blind as those who refuse to squeeze facts into pre-set ideologies.)
One major volcanic eruption puts more CO2 into the atmosphere than all human sources combined. How we gonna put a muzzle on that? BTW the answer is we’re not gonna be able to do it.
Jeez, look at that ugly bugger. I had forgotten all about those.
What model is it? Is the “75” on the windshield the year OR how much the owner had to pay someone to take it off his hands. LOL
Since it has been demonstrated that Carbon Dioxide increases in the atmosphere lag the global temperature by some 800 years has anyone bothered to investigate if The Carbon dioxide levels aren’t actually a natural regulatory mechanism that helps maintain the the planet’s equilibrium and if we continue to mess with it we will upset the balance in the the exact opposite to the original intended consequence?
A muzzle and a giant cork to close up the two huge pie holes on L. Ron Gore might be a start ;)
Well, yeah but the computer models have long ago stopped predicting we would see 20 feet rise in sea level, but that does not stop Al Gore from making a movie about it. Global Warmers do not let facts get in their way of putting out doom and gloom propaganda.
Did comet start deadly cold snap?
Canada.com | Monday, May 14, 2007 | Margaret Munro
Posted on 05/16/2007 6:00:33 PM EDT by Mike Darancette
Diamonds tell tale of comet that killed off the cavemen
Guardian | 5-20-07 | Robin McKie
Posted on 05/20/2007 7:50:33 PM EDT by Renfield
Catastrophic Comet Chilled and Killed Ice Age Beasts (and Clovis people)
Live Science | 05/21/07 | Jeanna Bryner
Posted on 05/22/2007 1:16:48 AM EDT by TigerLikesRooster
Oregon Researchers Involved In New Clovis-Age Impact Theory (More)
Posted on 05/23/2007 5:30:19 PM EDT by blam
Comet May Have Doomed Mammoths
Red Orbit | 5-26-07 | Betsy Mason
Posted on 05/26/2007 9:12:53 AM EDT by Renfield
And who caused the “comet”? But of course, human life.
PP43A-06 The Younger Dryas ET Impact Theory and Terminal Pleistocene Mammalian Extinctions in North AmericaPP05: New Insights into Younger Dryas Climatic Instability, Mass Extinction, the Clovis People, and Extraterrestrial ImpactsDespite decades of intensive study and debate, no consensus has been reached on what caused the extinction of North America's mammalian megafauna at the end of the Pleistocene. In a scholarly standoff, prominent scientists have shown that neither "human overkill" or "climate change" models adequately account for the patterns found in the paleontological and archaeological records of North America. The Younger Dryas ET Impact theory may dramatically alter this debate, adding a catastrophic trigger to help explain the rapid extinction of many large mammals about 12,900 years ago. New data suggest that an extraterrestrial impact focused in northern and eastern North America may have devastated the megafauna through: (1) direct mortality caused by the impacts shock wave, debris, and massive wildfires; (2) dramatic reduction of terrestrial food supplies, rapid climatic change, and ecological reorganization; and (3) coup-de-grace effects of surviving human populations rapidly expanding after the impact.
The deglaciation that followed the last ice age period was abruptly and dramatically interrupted ~12,900 years ago by widespread cooling that marks the onset of the Younger Dryas Cool Episode, an apparent climatic anomaly in Quaternary deglaciation behavior. Much evidence shows that the Younger Dryas onset was marked by abrupt changes in ice sheet configuration, diversion of North American flood-waters to the northern Atlantic, the sudden emptying of proglacial lakes, and the reorganization of thermohaline circulation that may have triggered severe cooling. Nevertheless, significant questions have recently emerged about timing and direction of major freshwater flows to the oceans, in turn raising questions about the triggering mechanism for the Younger Dryas. The onset of the Younger Dryas also appears to have coincided with massive, widespread and punctuated changes in animal biota and Paleolithic cultural development centered in North and South America. This is represented by the well-known extinction of the megafauna of the Americas, including mammoths, horses and groundsloths (the most recent of all mass extinctions) and the termination of Clovis and certain other contemporaneous Paleolithic human cultures. The cause of these changes is also highly controversial and much debated, but is likely tied to the severe environmental changes that occurred at the beginning of the Younger Dryas. Nevertheless, some researchers consider these to be coincidental events, while others link the two as cause and effect. Another hypothesis attributes the extinctions to overhunting by Clovis people and other Paleolithic hunters or to pandemics associated with human migrations. However, all these hypotheses appear to fall short in satisfactorily explaining much available evidence. A new hypothesis posits that Younger Dryas cooling was instead triggered by extraterrestrial impacts that caused ice sheet destabilization, flood-water rediversion and changes in ocean circulation. This work offers newly uncovered evidence for ET impact at 12.9 ka including end-Clovis age sediments throughout North America with high levels of Iridium, magnetic and carbon, spherules, glass-like carbon, fullerenes, and ET noble gas ratios often in association with carbonaceous black layers and succeeded by black mats with unusual biota In this session, we invite abstracts that will explore the strengths and weaknesses of existing and new hypotheses that attempt to explain the cause of the Younger Dryas and of associated changes in the global environmental system, the associated extinctions, and of human cultural changes. We welcome all abstracts exploring new perspectives on the chronology, stratigraphic succession and potential interconnections between a wide-range of processes that appear to have been associated with the Younger Dryas Episode. These include abrupt climatic change, ice-sheet deglaciation, flood-water rerouting, surficial geology, iceberg discharge, ocean reorganization including thermohaline circulation, and sea-level change. Also critical is the timing and nature of major extinction, Paleolithic cultural succession and impact-related phenomena.
Do you have a source or link for that? Good NFO to combat the hysteria.
OK, he said slowly.
What part of the 1500 year cycle are we in then? Medieval Warming would have to be defined fairly closely in order that we establish whether we are the end of the current warming cycle, the peak, or a new beginning.
Or whether we simply are watching the sun go nova a bit earlier than the astronomers predicted.
(After all, He told Noah that He’d never destroy the earth by flood again. That leaves fire as an obvious option.) 8<)
I think it is a ‘75. My in-laws had one a nice mustardy yellow color.
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At long last, we have a professional animation explaining how the Direct Fusion Drive works. Enjoy!
The audience learns, watching the movie “Solo,” that the Millennium Falcon has a nuclear fusion power plant! The Millennium Falcon is a modified YT-1330 Corellian light freighter manufactured by the Corellian Engineering Corporation.
The first soft moon landings were accomplished in the 1960’s by the Soviet Luna 9 and the U.S. Surveyor Spacecraft. These were followed by the U.S. Lunar Module landings during the Apollo program. The Soviets had their own LK Lander lunar lander for landing humans on the moon but it never flew. China’s Chang’e-3 landed on the moon on December 13, 2013. India plans to land the Chandrayaan-2 on the moon in 2018. South Korea intends to land a spacecraft on the moon in 2020.
The U.S. Lunar Module was flown by a crew but had a digital computer that performed guidance, navigation and control. A great new book by Don Eyles, Sunburst and Luminary an Apollo Memoir explains how that was accomplished with a computer less powerful than those in toaster ovens today. Don played a key role in saving the Apollo 14 mission when an abort light appeared on the crew’s console prior to descent. Read the book for for the whole story.
NASA intended follow-ons to the Lunar Module that would have been fully automated for delivering materials to the moon in preparation for a permanent human presence. Unfortunately, those plans never materialized.
As we are always looking for new missions for testing our Precision Attitude Control System, we added guidance, navigation and control for lunar landings. We use a really simple guidance algorithm called 2nd order guidance. It is nothing more than a Proportional Derivative (PD) controller with the landing spot as a target. You can adjust the damping ratio and undamped natural frequency of the controller to mimic more sophisticated, “optimal” guidance algorithms. The 2nd order guidance works until the lander gets near the surface and then it switches to landing algorithm that hovers, nulling any remaining translational velocities and then descends to the surface. Lidar would be used as guidance. Once it is hovering it would need to search for a flat spot for landing. NASA has developed Hazard Detection Software for Lunar Landing that uses lidar. It is available for licensing from Caltech.
Here is one simulation in our Simulation Framework. Once the descent is initiated, the spacecraft reorients so that the main engine thrust vector is in the desired direction. The display on the left shows the attitude errors (the two boxes) and the throttle setting (which is zero during the attitude maneuver.)
A close up of the attitude display. Pitch and yaw are offsets of the green rectangle. Roll is rotation of the rectangle. This is quite primitive but it is easy to add your own displays if you know a little OpenGL!
Descent starts and the throttle is about 50% at this point. The two plots are of altitude and velocity. The maneuver starts at 15 km and the target is 600 km along track. The lander has solar panels on a two-axis gimbal and a high gain antenna, also on a two-axis gimbal.
The spacecraft has landed! You can see the terminal descent phase on the altitude and velocity plots. The lunar surface is featureless because we have not added close up maps of the landing zone to the planet display.
The descent page shows the throttle settings. You can monitor the guidance force demand and simulated force.
The graphics are from our VisualCommander product that runs on Mac OS X.
This GN&C system is capable of autonomous flight from LEO all the way to the moon. It uses our Optical Navigation System, developed under a NASA Phase II SBIR for trajectory determination on the flight to the moon and lunar orbit entry.
For more information contact us directly!
Back in early September, PSS and PPPL were visited by a film crew from Australia. The project? Living Universe: An Interstellar Voyage, which will include a feature documentary, a 4 episode TV miniseries, and a podcast. The documentary touches all aspects of an interstellar mission, from exoplanets to astrobiology, including transportation – which is where our fusion engine work comes in. The film is in production now and the producers expect to launch in late 2018.
The PFRC experiment at PPPL is the only hardware the documentary team could find with a path to fusion propulsion! Dr. Cohen was able to run the machine for the film crew, and both Mike and Stephanie were interviewed extensively. We discussed the rocket equation and the fundamental speed of fusion products, and how DFD moderates that speed with additional propellant to produce higher thrust. For an interstellar voyage, DFD would have to be much, much lighter than we know how to make it today – but who knows what innovations in magnets are possible in the future!
How will you be able to watch the film and TV series? The film should do the rounds of museums and IMAX theaters. The TV series will be available for streaming from Curiosity Stream, a service which specializes in science, history, tech & nature documentaries. We will post an update when we have a firm release date!
I attended the 2017 Fusion Power Associates meeting in Washington, D.C. on December 6 and 7. Fusion Power Associates is a non-profit, tax-exempt research and educational foundation, providing timely information on the status of fusion development and other applications of plasma science and fusion research.
The annual meeting brought together experts in all areas of nuclear fusion research including scientists and engineers from ITER, the Princeton Plasma Physics Laboratory, TAE Technologies, General Atomic and many others! The meeting gave a great overview of the state of nuclear fusion power generation. We learned that ITER is 50% complete and on its way to first plasma in 2025. Planning has begun on Demo, the follow-on to ITER.
The Joint European Torus plans a D-T campaign in 2019 and hopes to set new fusion benchmarks. We learned about Korea Superconducting Tokamak Advanced Research (KStar). It has achieved longer than 70 second pulses in H-mode and has suppressed ELM for more than 34 seconds. KStar has in-vessel control coils.
There were several speakers from the University of Rochester along with colleagues from the national laboratories talking about advances in laser compression of fuel pellets. This work is for nuclear weapons research but could be applied to inertial confinement fusion.
I gave the last talk of the meeting on Princeton Satellite Systems and PPPL’s work on DFD, nuclear fusion propulsion for spacecraft.
We are pleased to report that an additional patent has been awarded for DFD! US Patent 9,822,769, “Method and Apparatus to Produce High Specific Impulse and Moderate Thrust from a Fusion-Powered Rocket Engine”, was published on Nov. 21, 2017. It’s now available from the US patent office website!
Here is a link to the patent from the Department of Energy’s Energy Innovation Portal! The inventor on the patent are Dr. Cohen, of PPPL, and three PSS engineers: Gary Pajer, Michael Paluszek, and Yosef Razin.
An interstellar asteroid, 1I/’Oumuamua, was discovered on a highly hyperbolic orbit by Robert Weryk on October 19, 2017 moving with a speed of 26.32 km/s. It appears to come from the direction of the star Vega in the constellation Lyra. It would be really great to send a mission to rendezvous and fly in formation with 1I/’Oumuamua to study the asteroid. The high velocity makes it hard to do with current technology.
Direct Fusion Drive (DFD) might provide a answer. We designed a spacecraft with a 1 MW DFD power plant and assumed a launch on March 16, 2030. The following plots show the trajectory and the force, mass and power of the spacecraft during the 23 year mission. As you can see we don’t have to use the full 1 MW for propulsion so we have plenty of power for data transmission and the science payload.
The Princeton International School of Mathematics and Science is a private secondary school in Princeton New Jersey.
One of their students, Savva Morozov, undertook a project to build a miniature 2-axis sun sensor for a CubeSat. Here is his blog post!
My name is Savva, I’m a senior at Princeton Int’l School of Math & Science. This summer I designed, built and tested a 2-axis solar tracking sensor for Princeton Satellite Systems.
The sensor can determine the relative position of the sun using a set of photodiodes. Bearing in mind that the solar sensor would be used in vacuum environment, I decided to make the sensor out of printed circuit boards (PCBs) and solder them to each other. Originally, I wanted to 3D print the sensor, but shifted to the PCB solution to eliminate the risk of outgassing.
Picture 1: solar tracking sensor, 2nd prototype.
My solar sensor design resembles the shape of a square-based pyramid that is approximately the size of a quarter. It consists of 5 PCBs: 4 sides and a base to which the sides are attached. Each side contains a photodiode, and by measuring the voltage outputs from at least 2 of the diodes, the device can determine the sunlight’s direction.
One of the initial problems I encountered was the handling and attachment of the photocells to the side PCBs. Each cell came with an anode and cathode wires already soldered to its front and back. I desoldered the cathode wire from every cell and affixed them to the PCB using a space grade silver conductive epoxy. This way I attached the cell to the device and grounded its cathode at the same time. I thought I killed two birds with one stone, but instead I killed two photodiodes: they were damaged in the soldering process. I resolved the issue in the second prototype: I threaded the cathode wire into a hole in a side PCB and then glued the diode to that same board. This way I didn’t have to use soldering iron at all, preventing possible risks. I then connected the cathode of every photodiode to a common ground and outputted the voltage readings from each cell in a single data bus.
Picture 2: Solar sensor, 2nd prototype, quarter for scale.
The diode, being attached to the outer side of the satellite, might be exposed to light that is reflected off the Earth or satellite surfaces. To partially prevent this, I soldered a shield to the edge of the sensor. Each surface of the shield would be covered with non-reflective material to further decrease the amount of ambient light.
To protect the diodes from the impacts of micrometeoroids and other space debris, I plan to cover the diodes with a thin shield of hard glass crystalline window (tempered glass or sapphire).
Testing the first prototype indicated a number of drawbacks that were solved in the second. Such problems are attaching the shield and the cells to the device, decreasing sensor’s size while increasing its aperture, and making the assembly process simpler.
I also calibrated photocell’s voltage outputs and their exact positions to account for manufacturing imperfections and for those created during the manual assembly of the device. I wrote a program to calculate the vector of sunlight direction and using Processing IDE created a visual representation of my sensor as well as its output result:
Picture 3: Visual illustration of a working solar sensor.
In order for my sensor to survive the vacuum environment, I attempted to use only space qualified materials in the device’s assembly: PCBs, solder, epoxy, and sheets of copper. I have finished working on the development stage of designing the solar sensor. Testing procedures on my last prototype showed that such device would be ready for further usage and launch.
Sadly, the AIAA Space Forum in Orlando, FL was canceled due to hurricane Irma. So, we didn’t get to present our paper on our DFD mission to Pluto. AIAA has, however, published all the forum papers and is providing free access for a few months in lieu of the actual conference. This means anyone can download it!
Fusion-Enabled Pluto Orbiter and Lander paper:
Open access to the AIAA Space Forum technical program: | <urn:uuid:5ac4e591-74eb-43d7-8ce8-f3a09c493940> | 3.296875 | 2,629 | Content Listing | Science & Tech. | 51.229142 | 95,599,726 |
In late 2013, when the neutron star at the heart of one of our galaxy's oddest supernovae gave off a massive burst of X-rays, the resulting echoes -- created when the X-rays bounced off clouds of dust in interstellar space -- yielded a surprising new measuring stick for astronomers.
Circinus X-1 is a freak of the Milky Way. Located in the plane of the galaxy, Circinus X-1 is the glowing husk of a binary star system that exploded a mere 2,500 years ago. The system consists of a nebula and a neutron star, the incredibly dense collapsed core of the exploded star, still in the orbital embrace of its companion star.
Circinus X-1 is a bizarre and sometimes frenetic source of X-rays in our galaxy. Residing in the plane of the Milky Way, where it cannot be observed by optical telescopes because of obscuring clouds of interstellar dust, Circinus X-1 is the glowing husk of a binary star system that exploded in a supernova event just 2,500 years ago. It consists of a very dense neutron star locked in the orbital embrace of a companion star. The system is called an X-ray binary because it flashes in X-rays as material from the companion star is sucked onto the dense neutron star.
Credit: NASA/Chandra X-ray Observatory
The system is called an X-ray binary because it emits X-rays as material from the companion star spirals onto the much denser neutron star and is heated to very high temperatures.
"In late 2013, the neutron star underwent an enormous outburst for about two months, during which it became one of the brightest sources in the X-ray sky," explains University of Wisconsin-Madison astronomy Professor Sebastian Heinz. "Then it turned dark again."
The flicker of X-rays from the odd binary system was monitored by a detector aboard the International Space Station. Heinz and his colleagues quickly mounted a series of follow-up observations with the space-based Chandra and XMM-Newton telescopes to discover four bright rings of X-rays, like ripples in a cosmic pond, all around the neutron star at the heart of Circinus X-1.
Their observations were reported June 23 in The Astrophysical Journal.
The rings are light echoes from Circinus X-1's X-ray burst. Each of the four rings, says Heinz, indicates a dense cloud of dust between us and the supernova remnant. When X-rays encounter grains of dust in interstellar space they can be deflected, and if the dust clouds are dense they can scatter a noticeable fraction of the X-rays away from their original trajectory, putting them on a triangular path.
That phenomenon, Heinz and his colleagues recognized, could give astronomers an opportunity to use the geometry of the rings and a time delay between deflected and undeflected X-rays to calculate the distance to Circinus X-1, a measurement previously unobtainable because the supernova is hidden in the dust that permeates the plane of our galaxy.
"We can use the geometry of the rings and the time delay to do X-ray tomography," Heinz explains. "Because the X-rays have traveled on a triangular path rather than a straight path, they take longer to get to us than the ones that were not scattered."
Combining those measurements with observations of the dust clouds by Australia's Mopra radio telescope, Heinz and his colleagues were able to determine which dust clouds were responsible for each of the four light echoes.
"Using this identification, we can determine the distance to the source accurately for the first time," according to the UW-Madison astronomer. "Distance measurements in astronomy are difficult, especially to sources like Circinus X-1, which are hidden in the plane of the galaxy behind a thick layer of dust -- which makes it basically impossible to observe them with optical telescopes.
"In this case, we used the dust that otherwise gets in the way to pioneer a new method of estimating distances to X-ray sources," Heinz says.
Now astronomers know that Circinus X-1, one of the Milky Way's most bizarre objects, is 30,700 light-years from Earth.
CONTACT: Sebastian Heinz, 608-890-1459, email@example.com
Terry Devitt, 608-262-8282, firstname.lastname@example.org
Sebastian Heinz | EurekAlert!
Subaru Telescope helps pinpoint origin of ultra-high energy neutrino
16.07.2018 | National Institutes of Natural Sciences
Nano-kirigami: 'Paper-cut' provides model for 3D intelligent nanofabrication
16.07.2018 | Chinese Academy of Sciences Headquarters
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.
"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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Temporal range: 416–0 Ma Devonian–Recent
|Hydrolagus colliei, a rat fish|
The subclass Holocephali ("complete heads") is a taxon of cartilaginous fish in the class Chondrichthyes. The earliest fossils are of teeth and come from the Devonian period. Little is known about these primitive forms, and the only surviving group in the subclass is the order Chimaeriformes. This group includes the rat fishes in the genus Chimaera, and the elephant fishes in the genus Callorhynchus. These fishes move by using sweeping movements of their large pectoral fins. They have long slender tails and live close to the seabed feeding on benthic invertebrates. They lack a stomach, food moving directly into the intestine.
Members of this taxon preserve today some features of elasmobranch life in Paleozoic times, though in other respects they are aberrant. They live close to the bottom and feed on molluscs and other invertebrates. The tail is long and thin and they move by sweeping movements of the large pectoral fins. The erectile spine in front of the dorsal fin is sometimes poisonous. There is no stomach (that is, the gut is simplified and the 'stomach' is merged with the intestine), and the mouth is a small aperture surrounded by lips, giving the head a parrot-like appearance. The only surviving members of the group are the rabbit fish (Chimaera), and the elephant fishes (Callorhynchus).
The fossil record of the Holocephali starts during the Devonian period. The record is extensive, but most fossils are teeth, and the body forms of numerous species are not known, or at best poorly understood. Some experts[who?] further group the orders Petalodontiformes, Iniopterygiformes, and Eugeneodontida into the taxon "Paraselachimorpha", and treat it as a sister group to Chimaeriformes. However, as almost all members of Paraselachimorpha are poorly understood, most experts suspect this taxon to be either paraphyletic or a wastebasket taxon.
|Taxonomy according to Joseph Nelson, 2006|
† Extinct * position uncertain
- Coates, M., Gess, R., Finarelli, J., Criswell, K., Tietjen, K. 2016. A symmoriiform chondrichthyan braincase and the origin of chimaeroid fishes. Nature. doi:10.1038/nature20806
- Pough, Janis & Heiser 2013, pp. 99,101, Table 5-1.
- Martin, lead section.
- Pough, Janis & Heiser 2013, pp. 103,105, Paleozoic Holocephalans.
- Revealing Less Derived Nature of Cartilaginous Fish Genomes with Their Evolutionary Time Scale Inferred with Nuclear Genes - NCBI - NIH
- Nelson 2006.
- Martin, R. Aidan; et al. "Chimaeras — The Neglected Chondrichthyans". Biology of Sharks and Rays. ReefQuest Centre for Shark Research. Retrieved 2016-02-22.
- Nelson, Joseph S. (2006). Fishes of the World. ISBN 978-0-471-25031-9.
- Pough, F. Harvey; Janis, Christine M.; Heiser, John B. (2013). Vertebrate Life (9th,international ed.). ISBN 978-0-321-78235-9.
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Smithsonian scientist challenges results of recent study
Late last year, Frédéric Achard and colleagues published a controversial article in which they contended that earlier estimates of worldwide tropical deforestation and atmospheric carbon emissions were too high. In the February 14 issue of Science, Philip Fearnside from the National Institute for Amazonian Research in Brazil, and William Laurance from the Smithsonian Tropical Research Institute in Panama argue that the Achard study contains serious flaws rendering its conclusions about greenhouse gases unreliable.
The article in question ("Determination of deforestation rates of the worlds humid tropical forests", Science, vol. 297, pages 999-1002), which received extensive press coverage, asserted that only about 0.6 to 1.0 billion tons of greenhouse gases (most carbon dioxide and carbon monoxide) were being produced by the razing and felling of tropical forests each year. This estimate is considerably lower than those of earlier studies, which estimated up to 2.4 billion tons annually.
Fearnside and Laurance list seven serious errors or limitations of the Achard study, which, they say, collectively lead to a major underestimate of greenhouse gas emissions.
Dr. Bill Laurance | EurekAlert!
Upcycling of PET Bottles: New Ideas for Resource Cycles in Germany
25.06.2018 | Fraunhofer-Institut für Betriebsfestigkeit und Systemzuverlässigkeit LBF
Dry landscapes can increase disease transmission
20.06.2018 | Forschungsverbund Berlin e.V.
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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Biology, images, analysis, design...
|"It has long been an axiom of mine that the little things are infinitely the most important" |
Black cherry aphidOn this page: Identification & Distribution Biology & Ecology Other aphids on the same host
Identification & Distribution:
Myzus cerasi is a small to medium sized aphid. Adult apterae (see first picture below) on the primary host are shiny, very dark brown to black with a sclerotized dorsum. The siphunculi are cylindrical and black with the distal part slightly curved outward. The legs and antennae are yellowish and black and the cauda is brown. The body length of Myzus cerasi apterae is 1.8-2.6 mm.
Most populations of the black cherry-aphid host alternate and have a sexual stage in the life cycle. Host alternation is between cherry (Prunus cerasus, Prunus avium) as the primary host and bedstraws (Galium), eyebrights (Euphrasia) and speedwell (Veronica spp) as the secondary hosts. However, colonies can be found on cherry throughout the summer. Forms on Prunus cerasus and Prunus avium are sometimes considered as different subspecies or even species. On the primary host Myzus cerasi cause the leaves to curl and produce leaf nests (see second picture at top of page). It is distributed throughout the palaearctic zone and is now almost cosmopolitan.
Biology & Ecology
Ant attendanceMyzus cerasi is avidly attended by ants. The colony below was attended by Myrmica rubra.
Gruppe (1990) looked at ant associations with Myzus cerasi in Germany. The trophobiotic association of Myzus cerasi with ants was not obligatory, colonies of the aphid being found without ants. Lasius niger and Myrmica laevinoides were the commonest species found with Myzus cerasi. Keeping ants away from cherry trees using sticky bands resulted in the development of fewer colonies of the aphid compared with untreated trees. On trees with ants, development of aphid colonies started from the central part and spread to many adjacent buds and shoots, where new colonies formed. Only isolated colonies occurred on trees without ants.
The colony above was attended by Lasius niger.
Other aphids on same host:
Blackman & Eastop list Myzus cerasi as found on 33 Prunus species worldwide, and provide formal identification keys. | <urn:uuid:54e61908-5147-4305-b627-e1c0a870171b> | 2.890625 | 538 | Knowledge Article | Science & Tech. | 36.420125 | 95,599,795 |
This video helps students understand the possible effect of increasing sea surface temperature on the intensity of hurricanes. The support materials provide an introduction to hurricanes and hurricanes as heat.
|Tool Name||The Effect of Sea Surface Temperature on Hurricanes|
|Discipline||Physics, Earth Sciences|
|Topic(s) in Discipline||Heat; Energy; Heat Engine; Hurricane; Hurricane Intensity|
|Climate Topic||Disasters and Hazards, Climate and the Atmosphere, Climate and the Hydrosphere|
|Type of Tool||Video|
|Grade Level||High School|
|Hosted at||PBS Learning Media| | <urn:uuid:9ad88300-729f-4a47-968d-bae08109e409> | 3.34375 | 130 | Truncated | Science & Tech. | -11.828056 | 95,599,854 |
Tracer experiments for the determination of chemical forms of radioiodine in water samples
Two simple methods, (1) isotope exchange method and (2) anion exchanger column method, are developed for the determination of chemical forms of radioiodine (iodide and iodate) in water samples. Using these methods, transformations of chemical forms of iodine in various water samples were studied. It was observed that iodate in rain water (unfiltered) and milk tended to change iodide form, whereas iodide was converted to iodate form in seawater and tap water. After the Chernobyl accident both chemical forms of131I (iodide and iodate) were found in rain water samples collected in Japan.
KeywordsJapan Iodine Water Sample Iodide Anion Exchanger
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- 2.D. C. WHITEHEAD, Environm. Intern., 10 (1984) 321.Google Scholar
- 3.M. KAHN, A. C. WAHL, J. Chem. Phys., 21 (1953) 1185.Google Scholar
- 4.N. IKEDA, Y. TAKAHASHI, K. TANAKA, K. KIMURA, Radioisotopes, 20 (1971) 48.Google Scholar
- 5.A. C. WAHL, N. A. BONNER, Radioactivity Applied to Chemistry. John Wiley and Sons Inc., New York, 1951, p. 29.Google Scholar
- 6.S. TSUNOGAI, T. SASE, Deep-Sea Res., 16 (1969) 489.Google Scholar
- 7.H. BEHRENS, IAEA STI/PUB/597, 1982, p. 27.Google Scholar
- 8.Y. MURAMATSU, M. SUMIYA, Y. OHMOMO, The Science of the Total Environment, 1987, in press.Google Scholar | <urn:uuid:4d02ba5d-e5ca-4da3-bfe7-95045b3b37d6> | 2.65625 | 417 | Academic Writing | Science & Tech. | 67.942286 | 95,599,881 |
A data type is a set of objects and a set of operations on those objects which create, build-up, destroy, modify and pick apart instances of the objects. Every programming language begins by supplying a set of data types. In LISP, the major data type is the binary tree (called an S-expression) and the basic operations are called CAR, CDR and CONS. More on this in Chapter 12. In modern imperative programming languages the usual built-in data types include integer, real, character and Boolean. Table 5-1 lists the built-in types for some of these languages.
KeywordsData Type Pointer Variable Character String Type Definition Null String
Unable to display preview. Download preview PDF. | <urn:uuid:96cb05c1-d96b-4f56-98f9-ccb938045e79> | 3.671875 | 148 | Truncated | Software Dev. | 49.544471 | 95,599,882 |
A semi-synthetic organism that stores and retrieves increased genetic information
Since the last common ancestor of all life on earth, the biological diversity has been encoded in a four letter, two base pair genetic alphabet. Expansion of the genetic alphabet to include a fifth and sixth letter than for a third, unnatural base pair not only has immediate utility for a number of applications, such as site-specific oligonucleotide labeling, but also serves as the foundation for an organism with an expanded genetic code. Toward this goal, we have examined a large number of different unnatural nucleotides bearing mainly hydrophobic nucleobase analogs that pair based on packing and hydrophobic interactions rather than H-bonding. Optimization based on extensive structure-activity relationship studies and two screens resulted in the identification of a class of unnatural base pairs that are well recognized by DNA and RNA polymerases. More recently, we have engineered E. coli to import the requisite unnatural triphosphates and shown that DNA containing the unnatural base pair is efficiently replicated, transcribed, and translated within the cell, resulting in the first semi-synthetic organism that stores and retreives increased information.
Enantioselective formation of remote tertiery and quaternary chiral centers
A long-standing challenge to synthetic organic chemists is the ability to forge stereocenters in substructures that do not contain pre-installed functional groups. In this regard, we have recently developed a catalytic and enantioselective intermolecular Heck-type reaction of multi-substituted alkenyl alcohols allowing for the installation of various groups (aryl and alkenyl) that are remote from the alcohol. The reported methods allow direct access to β-, γ-, δ-, or ζ aryl carbonyl functionalized compounds, as the unsaturation of the alkene is relayed to the alcohol resulting in the formation of a carbonyl. This is accomplished through a series of migratory insertion/β-hydride elmination events, which allows the Pd-center to chain walk to the prefunctionalized site in the molecule. In this lecture, the design, development, scope, and mechanistic analysis will be discussed of this reaction as well as new findings guided by the mechansitic insight garnered in our studies.
F. Dean Toste
Organic reactions inspired by the organometallic chemistry of gold
The past decade has witnessed remarkable development in the use of cationic gold(I) complexes as homogenous catalysts for the transformation of carbon-carbon π-bonds. Several years ago, we demonstrated that the reactivity of these complexes could be controlled by modification of the counter anion to these cationic transition metal complexes. This discovery provided a general platform for inducing enantioselectivity in reaction not only using cationic transition metal complexes, but also with reactive cationic reagents and intermediates. As an extension of this concept, we have been exploring the use of supramolecular assemblies as chiral anion for catalysis or as the anionic component in reactions catalyzed by cationic transition metal complexes. Finally, recent studies aimed at harnessing the reactivity of gold(III) will be introduced. This will include mechanistic studies on the reductive elimination for gold(III) and utility in carbon-carbon formation.
Utilization of the inherent stereochemical and functional diversities of natural products to produce unique biomedical materials
A primary interest in the Wooley laboratory is the production of functional polymers from renewable sources that are capable of reverting to those natural products once their purpose has been served. The inherent stereochemical and functional diversities of natural products provide opportunities to expand the scopes and complexities of polymer materials, by utilizing fundamental synthetic organic chemistry approaches. This presentation will highlight synthetic strategies for the development of polymers, block polymers and crosslinked network materials, which can be produced by relatively simple approaches from complex polyhydroxyl natural products and can be made to exhibit a range of properties. It is expected that the physical, mechanical, supramolecular assembly and stability properties will be tuned by the chemical compositions and structures, controlled by the advancement of synthetic methodologies by which to prepare such materials. Polycarbonates and polyphosphoesters that can be produced rapidly as well-defined block polymers and then undergo multiple chemical transformations and direct assembly in water into functional nanomaterials are serving as platforms for several directions toward their development as biomedical devices for the treatment of lung infections and osteosarcoma lung metastases. If time allows, recent developments toward the preparation of functional polypeptides and their assemblies will also be described.
Stereocontrol in photochemical reactions
Photochemistry is intriguing as a synthetic tool because the absorption of light by an organic molecule results in the formation of exceptionally energetic reactive intermediates that can react in ways that are inaccessible to ground-state molecules. However, this high reactivity is also a challenge for stereoselective synthesis: control over the stereochemistry of photochemical reactions, particularly using enantioselective catalysts, has been a long-standing challenging synthetic problem with few general solutions. We recently developed a method for highly enantioselective [2+2] photocycloaddition reactions using a combination of chiral Lewis acid and transition metal photocatalysis. This dual catalyst approach offers a robust strategy to control the reactivity of a wide range of reactive intermediates that can easily be generated using photoredox catalysis. | <urn:uuid:89872b0d-ec10-44f7-ac68-05e8a55cc585> | 2.53125 | 1,139 | Content Listing | Science & Tech. | -4.355409 | 95,599,911 |
Retained trivial and semisystematic names for heteromonocyclic compounds are given in R-9.1, Table 23 and Table 24.
Examples of Hantzsch-Widman names (R-22.214.171.124)
(Cyclohexagermane, according to R-2.3.2)
R-126.96.36.199.1 The position of a single heteroatom determines the numbering in a monocyclic compound.
R-188.8.131.52.2 When the same heteroatom occurs more than once in a ring, the numbering is chosen to give the lowest locants to the heteroatoms.
Example to R-184.108.40.206.1
R-220.127.116.11.3 When heteroatoms of different kinds are present, the locant 1 is given to a heteroatom which appears earliest in Table 3. The numbering is then chosen to give the lowest locants to the heteroatoms, first considered as a set without regard to kind; if a choice still remains, then to a heteroatom appearing earliest in Table 3.
Example to R-18.104.22.168.2
R-22.214.171.124 Heteromonocyclic compounds may be named by replacement nomenclature. However, replacement nomenclature for heteromonocycles with 10 or fewer members has usually been applied only to silicon-containing rings. Numbering follows R-126.96.36.199.
Examples to R-188.8.131.52.3
R-184.108.40.206 Saturated monocyclic systems consisting of repeating units of two different skeletal atoms may be named by citing successively the prefix "cyclo-" followed by a multiplying infix denoting the number of repeating units, the "a" terms of the atoms of the repeating unit in the reverse order to that given in R-9.3, and the suffix "-ane". The terminal letter "a" of an "a" term is elided when followed by a vowel; the terminal vowel of a numerical prefix is not elided even when the "a" term begins with the same vowel. Numbering follows, R-220.127.116.11.
Examples to R-18.104.22.168
Examples to R-22.214.171.124
Published with permission of the IUPAC by Advanced Chemistry Development, Inc., www.acdlabs.com, +1(416)368-3435 tel, +1(416)368-5596 fax. For comments or suggestions please contact firstname.lastname@example.org | <urn:uuid:c7ac839c-ba7b-4a6a-837a-99eb4af6bbc6> | 2.6875 | 569 | Structured Data | Science & Tech. | 81.145227 | 95,599,912 |
This has now been done by CNRS researcher Pascal Hersen (1) and the team led by Sharad Ramanathan at the Center for Systems Biology (Harvard University). Using a simple and innovative measuring device that they developed, the researchers have confirmed the hypothesis that above a certain stimulation frequency, the yeast cell no longer responds to osmotic stress (2).
They are now able to measure the rate of reaction to such stress, and above all, modify the reaction rate by eliminating certain genes. This work opens up new prospects for biological engineering. The idea is to construct cells with novel biological functions and whose dynamics can be controlled. These findings have been published on line on the web site of the journal /PNAS/.
Place a little salt on a cell and it immediately shrinks. This phenomenon is caused by the difference in salinity inside and outside the cell. To restore equilibrium between the concentrations, the cell releases some water, which reduces its size. In order to return to normal size, the cell undergoes a series of reactions that are essential for the efficient working of its regulation and adaptation processes. In the yeast Saccharomyces cerevisiae, a model eukaryotic (3) system, such a cascade has been well described. However, its dynamics remain poorly understood. A cell needs to react at the right rate in order to ensure its survival. It is therefore essential to understand the dynamics of cell response to environmental stress.
To this end, Pascal Hersen, CNRS researcher at the Complex Systems and Matter Laboratory (CNRS / Université Paris 7), and his US colleagues decided to study how and at what rate yeast responds and adapts to environmental stress. Using a simple device that makes it possible to follow the behavior of individual cells, they created an environment which periodically brings about disequilibrium. In this way they were able to determine the dynamic properties of cell response.
Their first observation was that when the frequency is too high, the size of the cells doesn't change. There simply isn't enough time for the transfer of water through the cell membrane to take place. On the other hand, for lower frequencies (input of disequilibrium every 10 seconds), the cells shrink and swell periodically, faithfully following the fluctuations of the disequilibrium. However, in this range of frequencies, there isn't enough time for the cascade of reactions to be activated between two cycles. There is thus a decoupling between the mechanical response and the biological response. It is only when the period is more than around ten minutes that the biological reactions are activated and follow one another 'naturally', while at the same time being coupled to the mechanical response of the cell. This frequency is therefore characteristic of the response dynamics in yeast, which is unable to faithfully follow changes in its environment that are too rapid, i.e. a period of less than ten minutes.
Finally, by eliminating certain genes from the yeast, the researchers showed that this cascade can be significantly slowed down. They now hope to understand how the quantity and nature of the proteins affects the dynamics of these reactions, and how they might eventually be able to speed them up or slow them down. Being able to manipulate them in this way opens up new prospects in synthetic biology (4) for the design of cells with novel functions, whose dynamics of response to stress can be controlled.
(1) Unité Matière et systèmes complexes (MSC, CNRS / Université Paris 7).
(2) Osmotic stress is caused by a difference in concentration of solute (such as salt) on either side of the cell membrane. Osmosis is the name given to the phenomenon of a return to equilibrium by diffusion of water through the membrane.
(3) A living organism which has a nucleus separated from the cytoplasm by a membrane and containing DNA.
(4) Synthetic biology is the engineering of living organisms. It consists in synthesizing complex systems based on biology which carry out functions that don't exist in nature.
Julien Guillaume | alfa
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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The international collaboration is comprised of researchers from the University of Colorado, USA and the Niels Bohr Institute at the University of Copenhagen and the results have just been published in the prestigious scientific journal, Science.
An atomic clock consists of gas atoms captured in a magnetic field where they are held stationary with precise laser light and are cooled down to near absolute zero, minus 273 degrees Celsius. In this state the researchers can use the quantum properties of the atoms and get them to function as a clock movement with a pendulum."An atom consists of a nucleus and some electrons that spin in clearly defined orbits around the nucleus. By using the focused laser light one can make the electron swing back and forth in a clearly defined way between these orbits, and it is that which forms the pendulum in the atomic clock", explains nuclear physicist at the Niels Bohr Institute at the University of Copenhagen, Jan W. Thomsen, who has worked with the new experiments together with researchers at the University of Colorado in Boulder, USA.
"The problem was that the atoms did not behave as they should according to the theory of quantum physics", tells Jan W. Thomsen and explains, that atoms have two fundamental states – they either rotate a complete revolution around themselves and are then called bosons or they rotate half-integers (½ or 1½) around themselves and are then called fermions. These two types behave completely differently. The bosons clump tightly together, while the fermions are repelled by each other and it is impossible to get them near to each other.
Journey into the quantum world
For atomic clocks one uses fermions because they do not interact – according to the theory of physics of quantum mechanics. Yet they did, as it turned out. And what was the reason? The researchers wanted to find out what was really happening and they started a colossal series of time consuming experiments that have given a whole new insight into how cold atoms behave.
"It was an fascinating journey into the world of quantum mechanics. We found out that not all fermions were the same. At the very low temperatures the fermions begin to 'see' each other and interact and then the atomic clock begins to go awry", explains Jan W. Thomsen. The experiments showed that the fermion's quantum properties were being affected by the exposure to light itself and this lead to the loss of precision in the atomic clock. By tuning the light frequency in a certain way one could control the fermions and avoid the loss of precision.
The result is that an atomic clock is now three times more precise than before and that the clock now loses only one second per 300 million years as opposed to one second per 150 million years. Even though it is only small fraction of a second, it has great potential in the application in areas having to do with the determination of great distances, for example, measuring the distance to distant galaxies in space. If one looks back towards the Earth one could measure the tiny movements in the continental drift and that can perhaps give geophysicists a new tool to work with to predict earthquakes.
The question is whether they are now satisfied with the atomic clock's precision? "Not completely", answers Jan W. Thomsen, "we dream of getting an atomic clock with perfect precision". So the research in the world of quantum mechanics continues towards a new goal.
Jan W. Thomsen, PhD. nuclear physicist, Niels Bohr Institute, University of Copenhagen, +45 3532-0463, +45 3532-0462, firstname.lastname@example.org
Gertie Skaarup | EurekAlert!
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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Are any of you signed up for the 2011 Ant Course? It is going to be held at the American Museum of Natural History's Southwestern Research Station near Portal, Arizona this year, or at least it was supposed to be. You see, there is a big fire burning in southeastern Arizona right now. They had to evacuate the station over the weekend.
And ants sure don't have those iridescent chelicerae in front. Or the row of eyes right above the chelicerae.
It's a jumping spider, apparently Myrmarachne formicaria. Look how the spider even holds its palps under the chelicerae to help with the disguise.
This is one of four males found overwintering in an old toy bulldozer left in the woods of upstate New York. We brought the toy inside and a day or so later noticed these. Once they had warmed up, they were quite active and readily accepted small flies.
Myrmarachne formicaria is a ant-mimic jumping spider that was first found in the United States (in Ohio) in 2001. Obviously its range is spreading.
Have you ever been fooled momentarily by a spider that was an ant mimic? Have you ever seen one of these?
Richard A. Bradley, Bruce Cutler, Maggie Hodge. 2006. The first records of Myrmarachne formicaria (Aranae, Salticidae) in the Americas. Journal of Arachnology. 34(2):483-484.
Have you heard about this? The harsh spotlight of agricultural fame has been taken off the social insects by the paper in Nature last month. It turns out that amoebae of the species Dictyostelium discoideum treat their food bacteria like leafcutter ants treat the fungi they eat. In fact, the single-celled wonders might be called "farmers."
Did you know there were social amoebae? When levels of their "prey bacteria" get low, the amoebae gather together to form what is called a migrating slug (see video below). The clustered amoebae move a certain distance, and then form a towering fruiting body, with a thin stalk supporting a round sorus at the top. The cells within the sorus form spores, which disperse.
Be patient for the first 30 seconds of the video. The amoebae have been deprived off food. It takes a bit of time, but then they form the slug. I wonder if the stragglers that try to catch up to the main slug should be called "sluglets?" 🙂 (You'll see what I'm talking about.)
When the "farmer" amoebae are ready to disperse, rather than eating absolutely all the bacteria available to them, they leave some. The bacteria are incorporated into the amoebae, into the slug, and carried via spores to the new area. Once at a suitable location to grow, the farmers "seed" the area with the bacteria, thus ensuring a certain food supply.
Non-farming clones of the same species of amoeba, on the other hand, consume all of the bacteria in the original area. Whether there will be food where their spores land is left to chance.
A fascinating species. And thanks to SN for bringing this to my attention,
This summer I stumbled upon a sweat bee nest while moving some old boards. The nest was between two boards and this is what it looked like when I lifted the top one off. (Sweat bees, family Halictidae, are often metallic, shiny green or blue.)
Sweat bees vary from solitary to social. This nest had multiple adults, which probably indicates they were living socially. Does anyone recognize the species?
All life stages were present. In this cell there is a ball of food and what looks like an egg (it seems to have a knob at one end?). Usually the food is a mixture of pollen and nectar, hence the yellow-orange color. See the water beads in the cell? The sweat bees line the cells with wax.
The older larvae are plump grubs. Prior to pupating, the larvae enter a resting stage called a prepupa.
Sweat bee pupae look like most bee pupae. You can see their eyes, mouthparts and antennae. This species does not appear to spin a cocoon.
Everything is pretty neat and tidy.
I tried to replace the board, but when I checked the next day, it was obvious the disturbance was too much. Many of the cells were empty.
The nest was overrun with snails (I think they ate the larval food),
and of course, ants.
What a difference a day makes in the life of a sweat bee. | <urn:uuid:26d72d39-a72f-4cb8-867a-63f97bb66d58> | 2.640625 | 993 | Personal Blog | Science & Tech. | 63.593797 | 95,599,935 |
Mason bee is a name now commonly used for species of bees in the genus Osmia, of the family Megachilidae. Mason bees are named for their habit of using mud or other "masonry" products in constructing their nests, which are made in naturally occurring gaps such as between cracks in stones or other small dark cavities; when available some species preferentially use hollow stems or holes in wood made by wood-boring insects.
Species of the genus include the orchard mason bee Osmia lignaria, the blueberry bee O. ribifloris, and the hornfaced bee O. cornifrons. The former two are native to the Americas and the latter to Japan, although O. lignaria and O. cornifrons have been moved from their native ranges for commercial purposes. The red mason bee, Osmia bicornis, is found across the European continent. Over 300 species are found across the Northern Hemisphere. Most occur in temperate habitats within the Palearctic and Neartic zones, and are active from spring through late summer.
Osmia species are frequently metallic green or blue, though many are blackish and at least one rust-red. Most have black ventral scopae which are difficult to notice unless laden with pollen. They have arolia between their claws, unlike Megachile or Anthidium species.
Historically, the term mason bee has also been used to refer to bees from a number of other genera under Megachilidae such as Chalicodoma, most notably in "The Mason-Bees" by Jean-Henri Fabre and his translator Alexander Teixeira de Mattos in 1914.
When the bees emerge from their cocoons, the males exit first. The males typically remain near the nests waiting for the females, and some are known to actively extract females from their cocoons. When the females emerge, they mate with one or several males. The males soon die, and within a few days the females begin provisioning their nests.
Osmia females typically nest in narrow gaps and naturally occurring tubular cavities. Commonly this means hollow twigs, but can be in abandoned nests of wood-boring beetles or carpenter bees, in snail shells, under bark, or in other small protected cavities. They do not excavate their own nests. The material used for the cell can be clay, mud, grit, or chewed plant tissue. The palearctic species O. avosetta is one of a few species known for lining the nest burrows with flower petals. A female might inspect several potential nests before settling in.
Within a few days of mating the female has selected a nest site and has begun to visit flowers to gather pollen and nectar for her nests; many trips are needed to complete a pollen/nectar provision mass. Once a provision mass is complete, the bee backs into the hole and lays an egg on top of the mass. Then, she creates a partition of "mud", which doubles as the back of the next cell. The process continues until she has filled the cavity. Female eggs are laid in the back of the nest, and male eggs towards the front.
Once a bee has finished with a nest, she plugs the entrance to the tube, and then may seek out another nest location.
Within weeks of hatching the larva has probably consumed all of its provisions and begins spinning a cocoon around itself and enters the pupal stage, and the adult matures either in the fall or winter, hibernating inside its insulatory cocoon. Most Osmia species are found in places where the temperature drops below 0 °C for long durations and they are well-adapted to cold winters; chilling seems to be a requirement for maturation. Some species of mason bees are semi-voltine, meaning that they have a two-year maturation cycle, with a full year (plus) spent as a larva.
Solitary bees produce neither honey nor beeswax. They are immune from acarine and Varroa mites, but have their own unique parasites, pests, and diseases. The nesting habits of many Osmia lend themselves to easy cultivation, and a number of Osmia are commercially propagated in different parts of the world to improve pollination in fruit and nut production. Commercial pollinators include O. lignaria, O. bicornis, O. cornuta, O. cornifrons, O. ribifloris, and O. californica. They are used both as an alternative to and as an augmentation for European honey bees. Mason bees used for orchard and other agricultural applications are all readily attracted to nesting holes – reeds, paper tubes, nesting trays, or drilled blocks of wood; in their dormant season they can be transported as intact nests (tubes, blocks, etc.), or as loose cocoons. As is characteristic of solitary bees, Osmia are very docile and rarely sting when handled (only under distress such as when wet or squeezed), their sting is small and not painful, and their stinger is unbarbed.
- Michener, Charles D. (2007). The Bees of the World (2nd ed.). Johns Hopkins University Press. ISBN 0801885736.
- Sedivy, C.D.; et al. (2013). "Host range evolution in a selected group of osmiine bees (Hymenoptera: Megachilidae): the Boraginaceae-Fabaceae paradox". Biological Journal of the Linnean Society. 108: 35–54. doi:10.1111/j.1095-8312.2012.02013.x.
- Fabre, Jean-Henri (1914). The Mason-Bees. New York: Dodd, Mead and Company.
- Sedivy, C.; et al. (2012). "Evolution of nesting behavior and kleptoparasitism in a selected group of osmiine bees (Hymenoptera: Megachilidae)". Biological Journal of the Linnean Society. 108: 349–360. doi:10.1111/j.1095-8312.2012.02024.x.
- Holland, Jennifer S. (October 2010), "Flower Beds", National Geographic, 218 (6).
- Zurbuchen, A.; et al. (2010). "Long foraging distances impose high costs on offspring production in solitary bees". Journal of Animal Ecology. 79: 674–681. doi:10.1111/j.1365-2656.2010.01675.x.
- Rozen, Jerome G.; et al. (2010). "Nests, Petal Usage, Floral Preferences, and Immatures of Osmia (Ozbekosmia) avosetta (Megachilidae: Megachilinae: Osmiini), Including Biological Comparisons to Other Osmiine Bees". American Museum Novitates. 3680: 1–22. doi:10.1206/701.1.
- Rozen, Jerome G.; et al. (2009). "Biology of the Bee Hoplitis (Hoplitis) monstrabilis Tkalcu and Descriptions of Its Egg and Larva (Megachilidae: Megachilinae: Osmiini)". American Museum Novitates. 3645: 1–12. doi:10.1206/646.1.; Sedivy, Claudio; Dorn, Silvia; Müller, Andreas (2012). "Molecular phylogeny of the bee genusHoplitis(Megachilidae: Osmiini) - how does nesting biology affect biogeography?". Zoological Journal of the Linnean Society. 167: 28–42. doi:10.1111/j.1096-3642.2012.00876.x.
- Kemp, Bosch, J., W.P. (2002). "Developing and establishing bee species as crop pollinators: the example of Osmia spp. (Hymenoptera: Megachilidae)". Bulletin of Entomological Research. 92: 3–16.
- Sheffield, C.S.; et al. (2008). "Diversity of cavity-nesting bees (Hymenoptera: Apoidea) within apple orchards and wild habitats in the Annapolis Valley, Nova Scotia, Canada". Can. Entomol. 140: 235–249. doi:10.4039/n07-058.
- Dogterom, Margeriet (2002). Pollination with Mason Bees: A Gardener's Guide to Managing Mason Bees for Fruit Production. Beediverse Publishing. ISBN 9780968935705.
- Bosch, Jordi and Kemp, William J. (2001). How to manage the blue orchard bee. Sustainable Agriculture Network Handbook Series. p. 98. ISBN 978-1888626063. Retrieved 3 October 2017.
|Wikisource has the text of the 1905 New International Encyclopedia article Mason Bee.|
- Osmia Identification Guide (female)
- Osmia Identification Guide (male)
- List of Species
- Worldwide Species Map
- Palaearctic Osmiine Bees
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A robot wheels across a rocky, windswept landscape that looks like the surface of some distant planet from a science fiction film. But it is not in outer space, it's on the slopes of Europe's most active volcano. Mount Etna, in Sicily, is a test bed for the approximately three-foot high, four-wheeled machine ahead of a future mission to the moon. It is being conducted by the German Aerospace Centre, the agency which runs Germany's space programme.
— DLR - English (@DLR_en) June 29, 2017
the programme has enlisted experts from Germany, Britain, the United States and Italy to research ROBEX (Robotic Exploration of Extreme Environments) with the aim of improving robotic equipment that will be used in space. "This is aimed at simulating a future, hypothetical landing mission on the moon or Mars and they use a lot of robots which are there to transport and install different instruments", said Boris Behncke, a volcanologist from the National Vulcanology Institute in Catania, near Mount Etna.
Scientists also hope to use the robots to explore the depths of Mount Etna and relay back useful technical data on seismic movement. The techniques learnt on Etna would then be deployed in lunar missions or in the exploration of Mars. An initial robotic testing phase has nearly been completed on the Piano del Lago area of the volcano, a desolate stretch of terrain buffeted by strong winds.
Next, a network of equipment including rover robots and drones will be mounted to monitor seismic activity that closely simulates that which would be used on the moon. | <urn:uuid:8f2b86a4-56e3-40c1-9375-a038b292744a> | 3.59375 | 325 | News Article | Science & Tech. | 35.193545 | 95,599,944 |
The human nose has millions of olfactory neurons grouped into hundreds of different neuron types. Each of these neuron types expresses only one odorant receptor, and all neurons expressing the same odorant receptor plug into one region in the brain, an organization that allows for specific odors to be sensed.
For example, when you smell a rose, only those neurons that express a specific odor receptor that detects a chemical the rose emits get activated, which in turn activates a specific region in the brain. Rotten eggs on the other hand, activate a different class of neurons that express a different (rotten egg) receptor and activate a different part of the brain. How the one-receptor-per-neuron pattern — critical for odor discrimination — is achieved in olfactory neurons is a mystery that has frustrated scientists for long.
Now a team of scientists, led by neurobiologists at the University of California, Riverside, has an explanation. Focusing on the olfactory receptor for detecting carbon dioxide in Drosophila (fruit fly), the researchers identified a large multi-protein complex in olfactory neurons, called MMB/dREAM, that plays a major role in selecting the carbon dioxide receptors to be expressed in appropriate neurons.
Study results appear in the Nov. 15 issue of Genes & Development. The research is featured on the cover of the issue.
According to the researchers, a molecular mechanism first blocks the expression of most olfactory receptor genes (~60) in the fly's antennae. This mechanism, which acts like a brake, relies on repressive histones —proteins that tightly wrap DNA around them. All insects and mammals are equipped with this mechanism, which keeps the large families of olfactory receptor genes repressed.
"How, then, do you release this brake so that only the carbon dioxide receptor is expressed in the carbon dioxide neuron while the remaining receptors are repressed?" said Anandasankar Ray, an assistant professor of entomology, whose lab conducted the research. "Our lab, in collaboration with a lab at Stanford University, has found that the MMB/dREAM multi-protein complex can act on the genes of the carbon dioxide receptors and de-repress the braking mechanism — akin to taking the foot off the brake pedal. This allows these neurons to express the receptors and respond to carbon dioxide."
Ray explained that one way to understand the mechanism in operation is to consider a typewriter. When none of the keys are pressed, a spring mechanism or "brake" can be imagined to hold the type bars away from the paper. When a key is pressed, however, the brake on that key is overcome and the appropriate letter is typed onto the paper. And just as typing only one letter in one spot is important for each letter to be recognized, expressing one receptor in one neuron lets different sensor types to be generated in the nose.
"If this were not the case, a single cell would express several receptors and there would be no diversity in sensor types," Ray said. "Our study then attempts to answer a fundamental question in neurobiology: How do we generate so much cellular diversity in the nervous system?"
Next, the researchers will test whether the receptor-braking mechanism they identified in Drosophila is also involved in other organisms like mosquitoes. They also will examine the other receptors in Drosophila to explain what de-represses each one of them.
Modulating response levels
The researchers also found that the activity of the MMB/dREAM multi-protein complex in Drosophila can alter levels of the carbon dioxide receptor and modulate the level of response to carbon dioxide.
"If you dial down the activity of the complex, you also dial down the expression of the carbon dioxide receptors, and the flies cannot sense carbon dioxide effectively," Ray said. "What's particularly encouraging is that this complex is highly conserved in mosquitoes as well, which means that we may be able to dial down the activity of this complex in mosquitoes using genetic strategies, and potentially lower the ability of mosquitoes to sense carbon dioxide, used by them to find human hosts. Because carbon dioxide receptors are so well conserved in mosquitoes, we expect that the regulatory mechanism we discovered in Drosophila may also be acting on mosquito carbon dioxide receptors."
Antenna versus maxillary palp
Interestingly, flies sense carbon dioxide with receptors located in their antennae, and avoid the source. Mosquitoes, on the other hand, are attracted to carbon dioxide and use receptors located not on their antenna but another organ called the maxillary palps (small structures present near the mouthparts). The research team found that two specific proteins in the multi-protein MMB/dREAM complex in mosquitoes have sequences that are quite different from those of the corresponding proteins in Drosophila.
"These proteins — E2F2 and Mip120 — could explain why Drosophila expresses carbon dioxide receptors in the antennae while the mosquito expresses them in its maxillary palp," Ray said.
The research done in Ray's lab was funded by a grant to Ray from the Whitehall Foundation. Besides Ray, UCR's Sarah Perry, the research paper's co-first author and a graduate student in the Genetics, Genomics and Bioinformatics program, and Sana Tharadra, a junior specialist in Ray's lab were involved in the research. They were joined in the work by Stanford University's Choon Kiat Sim, the co-first author of the research paper, and Joseph S. Lipsick, a professor of pathology and genetics.
The University of California, Riverside is a doctoral research university, a living laboratory for groundbreaking exploration of issues critical to Inland Southern California, the state and communities around the world. Reflecting California's diverse culture, UCR's enrollment has exceeded 21,000 students. The campus will open a medical school in 2013 and has reached the heart of the Coachella Valley by way of the UCR Palm Desert Center. The campus has an annual statewide economic impact of more than $1 billion. A broadcast studio with fiber cable to the AT&T Hollywood hub is available for live or taped interviews. UCR also has ISDN for radio interviews. To learn more, call (951) UCR-NEWS.
Iqbal Pittalwala | EurekAlert!
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Ormosils are organic-inorganic hybrid solids inwhichthe organiccomponentmaybe chemicallybonded to a silica matrix. Somewhat similar to inorganic silicate glasses, the structure of the silica network can be modified by the presence of organic groups. The resulting properties of the Ormosils are then governed by the type and concentration of organics used. Examples are presented in which the mechanical, electrical and optical properties of selected Ormosils can be influenced by organic groups. For instance, small amounts of polydimethylsiloxane (PDMS) added to a solution of TEOS will give an Ormosil about ten times harder than the hardest organic polymer. Larger amounts of PDMS (20%) will now yield an Ormosil which is as rubbery as organic rubber. Ormosils in which the organic and inorganic constituents are covalently bound to each other are the focus of this critical review. The potential applications of such Ormosils are discussed.
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Pumping liquid carbon dioxide underground on a massive scale so it won’t contribute to global warming has been talked about for years. Howard Herzog, an MIT chemical engineer and the program manager of the Carbon Sequestration Initiative, an industrial consortium, says the most recent international conference on the subject–in Trondheim, Norway, earlier this year–made clear two things: First, the geological questions are being resolved favorably. Second, without policies that put a price on CO2, it’s unlikely that any sequestration facilities will actually get built.
TR: How has interest in this field grown?
Herzog: When this international conference series started in 1992, it had 250 people and less than 100 papers. We had 1,000 people in Norway, and 500 papers.
TR: Norway was the first to enact a CO2 tax, in 1991. How has this played out?
Herzog: It sent a signal to see if there was a way to reduce CO2 emissions and resulted in a large project in the North Sea to sequester carbon dioxide from a natural-gas field.
TR: What do we know about its performance?
Herzog: There is no indication of any leaks, and they’ve done some seismic tests that show the CO2 is staying in the underground geological formation. The amount of monitoring hasn’t been such that you can say for certain there are no leaks–but none has been detected.
TR: What about the question of geologic suitability generally?
Herzog: At the Norway meeting, the biggest category of papers was on geological storage. I think the work coming out says they are gaining a higher degree of confidence that this will work–and work well, if implemented with good practices.
TR: What else is emerging on the policy front?
Herzog: With a European carbon-trading system, several utilities have announced projects to build plants with CCS [carbon capture and storage], which is indicating at least at the high level that those price signals were enough to induce serious interest.
Outside of Europe, despite the lack of specific policies, there is still a lot of interest in this technology. People feel that over the next 10 years, policies will be put in place throughout most of the developed world.
TR: What will it take to get sequestration projects built?
Herzog: Utilities are not going to build them unless the policy is in place or they are really sure that policy is imminent. It’s easier to announce projects than build them.
TR: How about in the United States?
Herzog: In the next three years, the chances of anything happening are negligible. But within the next 10 years, I think the chances are greater than 50/50 that we’ll have some kind of carbon policy. I think no matter who is elected in the 2008 election, there will be changes.
SAMPLING OF LARGE-SCALE PROPOSED PROJECTS TO CAPTURE CO2
Company or consortium (location)Fossil fuelFate of CO2Possible openingBP (Scotland)Natural gasEnhanced oil recovery2009BP (California)Petroleum CokeEnhanced oil recovery2011Statoil/Shell (Norway)Natural gasEnhanced oil recovery2011FutureGen (United States)CoalSequestration2012RWE (U.K. and Germany)CoalSequestration2014 and 2016Monash (Australia)CoalEnhanced oil recovery2015Vattenfall (Germany)CoalSequestration2015
Source: MIT Laboratory for Energy and the Environment
Couldn't make it to EmTech Next to meet experts in AI, Robotics and the Economy?Go behind the scenes and check out our video | <urn:uuid:3bca1202-5e55-4f8f-931c-485a5b330e33> | 3.109375 | 773 | Audio Transcript | Science & Tech. | 44.275946 | 95,599,949 |
The sea bed could be one big battery.
Researchers name the microbes that could produce power by munching pollution.
Bacteria could clear up oil spills and generate electricity at the same time. US scientists have identified microbes that produce power as they digest organic waste1.
The bacteria strip electrons from carbon in ocean sediments to convert it into the carbon dioxide they need for metabolism and growth. Usually the organisms just dump the electrons onto iron or sulphate minerals on the ocean floor.
The Oregon team knew that the electrical energy was coming from microorganisms, but they didn’t know which creatures were involved. Now Derek Lovley of the University of Massachusetts at Amherst and colleagues have identified the culprits by making sediment batteries in the laboratory and analysing the bacteria clustered on one of the electrodes. The organisms belong to the family Geobacteraceae.
Lovley’s team also found that some freshwater-dwelling members of the family can do the same thing. These might be put to work in aquifers contaminated by oil or sewage, Lovley suggests.
Freshwater Geobacteraceae can break down petroleum in polluted groundwater on their own, but are often hampered by the lack of sufficient electron acceptors (such as the iron minerals). By providing these bacteria with an electrode that carts the electrons away, researchers could help bioremediation to proceed - and can capture a little electricity into the bargain.
PHILIP BALL | © Nature News Service
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For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
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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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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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“We certainly were surprised to find such a bright young galaxy 13 billion years in the past”, said astronomer Garth Illingworth of the University of California, Santa Cruz, USA and a member of the research team. “This is the most detailed look to date at an object so far back in time.”
According to the authors, the measurements are “highly reliable”. “This object is the strongest candidate for the most distant galaxy so far”, states team member Piero Rosati from ESO, Germany.
“The Hubble images yield insight into the galaxy’s structure that we cannot get with any other telescope,” added astronomer Rychard Bouwens of the University of California, Santa Cruz, one of the co-discoverers of this galaxy.
The new images should offer insights into the formative years of galaxy birth and evolution and yield information on the types of objects that may have contributed to ending the dark ages. During its lifetime the Hubble telescope has peered ever farther back in time, viewing galaxies at successively younger stages of evolution. These snapshots have helped astronomers create a scrapbook of galaxies from infancy to adulthood. The new Hubble and Spitzer images of A1689-zD1 show a time when galaxies were in their infancy.
Current theory holds that the dark ages began about 400,000 years after the Big Bang, as matter in the expanding Universe cooled and formed clouds of cold hydrogen. These cold clouds pervaded the Universe like a thick fog. At some point during this era, stars and galaxies started to form. Their collective light heated and cleared the fog of cold hydrogen, and ended the dark ages about a billion years after the Big Bang.
“This galaxy presumably is one of the many galaxies that helped end the dark ages”, said astronomer Larry Bradley of Johns Hopkins University in Baltimore, USA, and leader of the study. “Astronomers are fairly certain that high-energy objects such as quasars did not provide enough energy to end the dark ages of the Universe. But many young star-forming galaxies may have produced enough energy to end it.”
The galaxy is so far away it did not appear in visible light images taken with Hubble’s Advanced Camera for Surveys, because its light is stretched to infrared wavelengths by the Universe’s expansion. It took Hubble’s NICMOS, Spitzer and a trick of nature called gravitational lensing to see the faraway galaxy.
The astronomers used a relatively nearby massive cluster of galaxies known as Abell 1689, roughly 2.2 billion light-years away, to magnify the light from the more distant galaxy directly behind it. This natural telescope is a gravitational lens. Abell 1689 is one of the most spectacular gravitational telescopes known and its gravitational properties are very well known.
Though the diffuse light of the faraway object is nearly impossible to see, gravitational lensing has increased its brightness by nearly 10 times, making it bright enough for Hubble and Spitzer to detect. A telltale sign of the lensing is the smearing of the images of galaxies behind Abell 1689 into arcs by the gravitational warping of space by the intervening galaxy cluster. Piero Rosati says: “This galaxy lies near the region where the galaxy cluster produces the highest magnification – which was essential to bring this galaxy within reach of Hubble and Spitzer.”
Spitzer’s images show that the galaxy’s mass is typical of galaxies in the early Universe. Its mass is equivalent to several billions of stars like our Sun, or just a tiny fraction of the mass of the Milky Way.
“This observation confirms previous Hubble studies that star birth happens in very tiny regions compared with the size of the final galaxy”, Illingworth said.
The faraway galaxy also is an ideal target for Hubble’s successor, the James Webb Space Telescope (JWST), scheduled to launch in 2013. Even with the increased magnification from the gravitational lens, Hubble’s sharp “eye” can only see knots of the brightest, heftiest stars in the galaxy. The telescope cannot pinpoint fainter, lower-mass stars, individual stars, or the material surrounding the star-birth region. To see those things, astronomers will need the infrared capabilities of JWST currently being developed by NASA, ESA and CSA in a major international collaboration. The planned infrared observatory will have a mirror about seven times the area of Hubble’s primary mirror and will collect more light from faint galaxies. JWST also will be able to view even more remote galaxies whose light has been stretched deep into infrared wavelengths that are out of the reach of NICMOS.
“This galaxy will certainly be one of the first objects that will be observed by JWST”, said team member Holland Ford of Johns Hopkins University. “This galaxy is so bright that JWST will see its detailed structure. This object is a pathfinder for JWST for deciphering what is happening in young galaxies.”
The astronomers noted that the faraway galaxy also would be an ideal target for the ESO/NRAO/NAOJ Atacama Large Millimeter Array (ALMA), which, when completed in 2012, will be the most powerful radio telescope in the world. “ALMA and JWST working together would be an ideal combination to really understand this galaxy”, Illingworth said, noting that: “JWST’s images and ALMA’s measurement of the gas motions will provide revolutionary insights into the very youngest galaxies.”
The astronomers will conduct follow-up observations with infrared spectroscopy to confirm the galaxy’s distance using ESO’s VLT and the Keck telescope atop Mauna Kea in Hawaii.
Lars Christensen | alfa
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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
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20.07.2018 | Materials Sciences | <urn:uuid:bbe25370-0430-4846-a11c-915bd61663ae> | 3.5 | 1,793 | Content Listing | Science & Tech. | 40.035914 | 95,600,014 |
Introduction:Python is a high-level, structured, open-source programming language that can be used for a wide variety of programming tasks. Python was created by Guido Van Rossum in the early 1990s; its following has grown steadily and interest has increased markedly in the last few years. Another great feature of Python is its availability for all platforms. Python can run on Microsoft Windows, Macintosh and all Linux distributions with ease. This makes the programs very portable, as any program written for one platform can easily be used on another.
Python requires some setup by downloading the Python IDLE. You can download python from www.python.org. The Python IDLE is basically a text editor that lets you execute Python code. If you want to use Python as a server-side language, you certainly can. Python can output HTML just like other languages can.
Downloading And Installing Python:1. Go to www.python.org and download appropriate version
2. if your are not sure, which version to download, i recommend to download version 3.5 or higher
3. If you don't have notepad plus plus, download it from here.
4. You can directly run your python code from notepad plus plus using python shell. However you need to configure correctly. you can follow this youtube link.
5. You can also write code in Notepad, and run it on Windows command prompt. You may follow this video by Chuck Severance.
6. However, the best option I would suggest is installing PyCharm IDE.
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Search Engine Optimization services. Contact email@example.com | <urn:uuid:161e9007-d53b-4242-97f3-622fe6308c32> | 3.09375 | 364 | Personal Blog | Software Dev. | 52.630395 | 95,600,021 |
SYDNEY (AP) — Mass bleaching has killed more than a third of the coral in the northern and central parts of Australia's Great Barrier Reef, though corals to the south have escaped with little damage, scientists said on Monday.
Researchers who conducted months of aerial and underwater surveys of the 2,300-kilometer (1,400-mile) reef off Australia's east coast found that around 35 percent of the coral in the northern and central sections of the reef are dead or dying, said Terry Hughes, director of the ARC Centre of Excellence for Coral Reef Studies at James Cook University in Queensland state. And some parts of the reef had lost more than half of the coral to bleaching.
The extent of the damage, which has occurred in just the past couple of months, has serious implications, Hughes said. Though bleached corals that haven't died can recover if the water temperature drops, older corals take longer to bounce back and likely won't have a chance to recover before the next bleaching event occurs, he said. Coral that has died is gone for good, which affects other creatures that rely on it for food and shelter.
"Is it surprising? Not anymore. Is it significant? Absolutely," said Mark Eakin, the coral reef watch coordinator for the U.S. National Oceanic and Atmospheric Administration. "We're talking about losing 35 percent of the population of coral in some of these reefs — that's huge."
The damage is part of a massive bleaching event that has been impacting reefs around the world for the past two years. Experts say the bleaching has been triggered by global warming and El Nino, a warming of parts of the Pacific Ocean that changes weather worldwide. Hot water puts stress on coral, causing it to turn white and become vulnerable to disease. Other reefs have suffered even more severely from the recent bleaching; Some Pacific islands, for example, have reported coral death rates of more than 80 percent, Eakin said.
This is the third and most extreme mass bleaching event in 18 years to strike the Great Barrier Reef. In each case, the areas that suffered the worst bleaching were the areas where the water was hottest for the longest period of time, Hughes said.
This time, the southern half of the reef was spared largely due to a lucky break that arrived in the form of a tropical cyclone. The remnants of the storm which had lashed the South Pacific brought cloud cover and heavy rains to the region, cooling the ocean enough to stop bleaching that had just begun in the south. About 95 percent of the coral in the southern portion of the reef has survived.
Storms have previously proven very helpful for heat-stressed reefs, Eakin said. In 2005, for instance, the quick succession of Hurricane Katrina and Hurricane Rita cooled the waters below as they passed over Florida, sparing the Florida Keys from a serious coral bleaching event affecting the Caribbean.
Experimental approaches to the bleaching dilemma have included attempts to lower water temperatures by using shades to cover corals, Eakin said. But such efforts require massive amounts of preparation and can only be done in small areas, Eakin said. Other solutions may lie in finding ways to minimize additional stressors to the already fragile reef.
"Anything you can do to reduce the level of injury and stress coming from other sources, the better the chance that the corals are going to survive," Eakin said. "Those reefs that have recovered after events like this are the ones that are the most protected, least visited and least disturbed."
Last year, the United Nations' heritage body expressed concern about the state of the Great Barrier Reef and urged Australia to boost its conservation efforts.
Following the release of the bleaching report on Monday, Australian politicians — who are in the midst of an election campaign — jumped on the issue, with the opposition Labor Party pledging to create a $500 million fund for better management and research of the reef. Environment Minister Greg Hunt, meanwhile, announced that if his party is re-elected, the government would invest $6 million to helping combat the crown-of-thorns starfish, which feast on coral. | <urn:uuid:eeb152cd-47b9-4418-b2a0-94870b5b3af5> | 3.125 | 847 | News Article | Science & Tech. | 47.75751 | 95,600,027 |
Let's turn the table. Suppose your goal is to deliberately create buggy programs in C and C++ with serious security vulnerabilities that can be "easily" exploited. Then you need to know about things like stack smashing, shellcode, arc injection, return-oriented programming. You also need to know about annoying protection mechanisms such as address space layout randomization, stack canaries, data execution prevention, and more. This session will teach you the basics of how to deliberately write insecure programs in C and C++. Warning: there will be lots of assembler code in this talk. | <urn:uuid:37e033bb-620d-4e71-8a4d-f1c8738105a8> | 2.796875 | 117 | Truncated | Software Dev. | 43.333333 | 95,600,028 |