text stringlengths 174 655k | id stringlengths 47 47 | score float64 2.52 5.25 | tokens int64 39 148k | format stringclasses 24 values | topic stringclasses 2 values | fr_ease float64 -483.68 157 | __index__ int64 0 1.48M |
|---|---|---|---|---|---|---|---|
- Immediate mode simply means you specify what to redraw on every frame, there is no caching unless you specify it. And you basically redraw whenever some state changes (in a game this is going to be at frame rate).
- In React, when some state changes, you respecify the DOM for components whose state has changed, but asynchronously the library determines how to make the DOM update more efficient on the next frame redraw.
- Retained-mode means you modify the scene graph (aka DOM) using imperative statements, it is difficult to keep your UI in synch with your models. With immediate-mode, you simply create a function f(m) over your model m to render it on each frame rate (which also often involves imperative instructions affecting the frame buffer, but the buffer can be cleared on each frame so who cares).
- Retained-mode caches by default (often in opaque ways), which was the whole point (only re-render parts of the scene that have changed). You can roll your own caching for immediate mode, usually via some kind of invalidation scheme (use image for a node if nothing changed for this component, otherwise call that node's re-render method). On the other side, projects like React takes the retained-mode DOM and make it look more like an immediate-mode abstraction without sacrificing so much performance.
- The core premise for React is that UIs are simply a projection of data into a different form of data. | <urn:uuid:757d532c-edf2-461c-a974-94494e69dbf9> | 2.75 | 305 | Knowledge Article | Software Dev. | 34.097108 | 95,502,995 |
This article presents basic concepts related to the thermodynamics of sorption of water and measurement of sorption isotherm for food materials. A comprehensive review of the widely used sorption models is presented. Various statistical techniques used to ascertain the effectiveness of a model to describe the sorption data are discussed. It is anticipated that this article will provide useful information to researchers pursuing work on sorption behavior of food materials as well as modeling of drying processes.
Mendeley saves you time finding and organizing research
Choose a citation style from the tabs below | <urn:uuid:68aad981-8191-4f71-a969-d8f551a8df38> | 2.953125 | 109 | Academic Writing | Science & Tech. | 14.03625 | 95,502,998 |
Human beings consume foods like cereals, vegetables, pulses, fruits, meat, nuts, seeds, etc. to gain energy for their survival. Have you ever wondered how do plants survive, what do they eat and from where they get the stuff? Plants do need food for their survival and they would not wait or depend on others to provide them with food. There is a particular mechanism in plants with which they prepare their food. This mechanism is known as Photosynthesis.
Photosynthesis is a biological process used by plants to prepare their food with the help of sunlight and energy. The name photosynthesis is derived from the Greek word–Photo- meaning light and Synthesis meaning connecting together. This means combining together with the help of light energy.
This process is also used by algae and several bacteria to convert solar energy into chemical energy. Oxygen is liberated as a by-product, and light is considered as the major factor to complete the process of photosynthesis. This process occurs usually when plants use light energy to convert carbon dioxide and water into glucose and oxygen gas. Leaves are made up of small cells which have a tiny structure known as chloroplasts. Each chloroplast contains a green colored pigment so-called chlorophyll. Light energy is absorbed by chlorophyll molecules whereas carbon dioxide (CO2) and oxygen (O2) enter through the tiny pores of stomata located in the epidermis of leaves.
Oxygen is considered one of the most important by-products of this process on which most of the living organism depend upon. Glucose/Sugar is a form of carbohydrates that is processed during the process of photosynthesis. It is commonly used by green plants in the form of an energy source to produce leaves, fruits, flowers, and seeds. The glucose molecules then combine with each other to develop more complex carbohydrates like cellulose and starch. The cellulose is considered as the structural material that is used in plant cell walls. The overall reaction of photosynthesis process is:
|6CO2 + 6H2O —-> C6H12O6 + 6O2|
Where does Photosynthesis occur?
Photosynthesis occurs mainly in leaves of specialized cell structures known as chloroplasts.
- A leaf comprises a petiole, epidermis and a lamina.
- The Lamina is used for absorption of sunlight and carbon dioxide during the process.
- This process that occurs, takes place in chloroplasts that contain a green colored pigment called chlorophyll which is mainly responsible for green colored leaves.
- During the process of photosynthesis, chlorophyll absorbs the light energy from the sun to split water molecules into hydrogen and oxygen.
- The hydrogen from water molecules and carbon dioxide absorbed from the air are used in the production of glucose and the oxygen is liberated into the atmosphere through the leaves.
Glucose is a source of food for plants which provide energy for the growth and development, while the rest is stored in the roots, leaves, or fruits for their later use.
Pigments are other fundamental cellular components of photosynthesis. They are the molecules which impart color and they absorb light at some specific wavelength and reflect back the unabsorbed light. All green plants mainly contain chlorophyll a, chlorophyll b, and carotenoids which are present in the thylakoids of chloroplasts and help them in capturing the light energy. Chlorophyll a is the main pigment.
Structure of chlorophyll
Stages of Photosynthesis
Photosynthesis comprises two phases.
Light-dependent reaction (or) Light reaction.
Photosynthesis begins with the light reaction which is carried out only during the day in the presence of sunlight. In plants, the light-dependent reaction takes place in the thylakoid membranes of chloroplasts. The Grana, membrane-bound sacs like structures present inside the thylakoids functions by gathering light and is called as photosystems. These photosystems have large complexes of pigment and proteins molecules present within the plant cells which plays the primary role during the process of light reactions. There are two types of photosystems: photosystem I and photosystem II.
Under the light-dependent reactions, the light energy is converted to ATP and NADPH which are used in the second phase of photosynthesis. During the light reactions, ATP and NADPH are generated by two electron transport chains, water is used and oxygen is produced.
The chemical equation in the light reaction can be reduced to:
|2H2O + 2NADP+ + 3ADP + 3Pi → O2 + 2NADPH + 3ATP|
Light-independent reaction (or) Dark reaction.
Dark reaction is also called carbon-fixing reaction. It is a light-independent process in which sugar molecules are formed from the water and carbon dioxide molecules. The dark reaction occurs in the stroma of the chloroplast where they utilize the NADPH and ATP products of the light reaction. Plants capture the carbon dioxide from the atmosphere through stomata and proceed to the Calvin cycle. In the Calvin cycle, the ATP and NADPH formed during light reaction drive the reaction and convert 6 molecules of carbon dioxide into one sugar molecule or glucose.
The chemical equation for the dark reaction can be reduced to:
|3CO2 + 6 NADPH + 5H2O + 9ATP → G3P + 2H+ + 6 NADP+ + 9 ADP + 8 Pi|
* G3P – glyceraldehyde-3-phosphate
Importance of Photosynthesis
- It is essential for the existence of life on planet earth both as a source of food, shelter, and energy.
- This process is responsible for supplying all of the earth’s organic compounds and the energy required to sustain life on the planet.
- It is also responsible for maintaining and balancing the atmosphere’s oxygen and carbon dioxide levels and protects our planet from global warming
Factors affecting Photosynthesis
There are several factors that are required at an optimum level for a constant rate of photosynthesis.
- Light Intensity: Increased light intensity results in the high rate of photosynthesis and low light intensity would be considered as a low rate of photosynthesis.
- The concentration of CO2: Higher concentration of carbon dioxide helps in increasing the rate of photosynthesis. Usually,0.03 to 0.04 percent concentration of carbon dioxide is adequately for photosynthesis.
- Temperature: For an efficient execution of the process, it is important to have an optimum temperature that ranges between 25° to 35° C.
- Water: As water is an important factor in this process, lack of water can lead to a problem of intake of carbon dioxide. The scarcity of water leads to refusal of stomatal opening to retain the amount of water they have stored inside.
- Polluted Atmosphere: All the pollutants and gases when settles on leaves surface, it blocks the pores of stomata which makes it difficult to take in carbon dioxide.
To learn more about photosynthesis with video lessons, visit BYJU’S.
Practise This Question | <urn:uuid:c855e41f-7d59-40f2-8d5f-1931d531709b> | 3.984375 | 1,476 | Knowledge Article | Science & Tech. | 38.01275 | 95,503,022 |
Brett Gibson, an assistant professor of psychology who studies animal behavior, details his latest research in the journal article, “Non-accidental properties underlie shape recognition in mammalian and non-mammalian vision,” published today in Current Biology. Gibson and his colleagues found that humans and pigeons, which have different visual systems, have evolved to use similar techniques and information to recognize objects.
“Understanding how avian visual systems solve problems that require considerable computational prowess may lead to future technological advances, such as small visual prosthetics for the visually impaired, in the same way that understanding visual processing in honeybees has led to the development of flying robots and unmanned helicopters,” the researchers say.
So a software engineer who wants to design a program to help a robot recognize objects can get a leg up from evolution, which has been developing “programs” for object recognition in animals long before humans ever thought of doing such things, Gibson says. “To the extent that we can learn how different animals recognize objects and whether they are doing the same things or different things based on their environments may really help us in designing our own system of object recognition.”
Gibson and his colleagues from the University of Iowa (Olga Lazareva and Edward Wasserman), the University of Montreal (Frédéric Gosselin), and the University of Glasgow (Philippe Schyns) found that pigeons, like humans, primarily rely on corners (coterminations) of an object in order to recognize it instead of relying on other features such as shading and color.
For example, a person could easily identify a AA battery from the side profile. But, let’s say the person could see the same battery only from the bottom with the negative terminal. From this perspective, the only visible outline would be a circle; from the bottom, the corners of the battery now are not visible and information about the corners cannot be seen.
“The task of recognizing the object becomes much more difficult. For most people, it would take them a bit longer to recognize the image as a battery,” Gibson says.
The researchers employed a new procedure, which Gosselin and Schyns developed, called Bubbles, to determine what features humans and pigeons were using to recognize objects. Three pigeons were trained to recognize four objects: an arch, a barrel, a brick, and a wedge. The researchers then partially revealed different parts of the object pictures. They then conducted the same experiment with six people.
Not only did both the pigeons and people recognize the four objects based mostly on corners, but they used these properties more than the shading information contained in the images. More notably, the pigeons and people used corner information more than a computer programmed to extract the most useful information for recognizing the object pictures, which suggests that the pigeons and people were using comparable information.
“When members of different species respond similarly to the same visual information, we gain confidence in the prominence of this information, irrespective of cultural or genetic influences. Birds represent an important group to compare with mammals, the other major class of warm-blooded, highly mobile, visually oriented animals,” the researchers say.
“Because of the unique demands of flight, for the last 200 million years birds have been under strong evolutionary pressures to keep their overall size to a minimum. Although a very large portion of the avian central nervous system is devoted to visual processing, the bird brain is still just a fraction of the size of our own. It is this extraordinary mixture of visual competence and small size that makes the study of birds critical to our understanding of the general mechanisms of visual cognition,” they say.
In addition to his research on vision, Gibson has done extensive research involving navigation and memory in birds. He is currently investigating how the Clark’s nutcracker uses different types of spatial information to return to hidden stores of food during winter. More information: www.unh.edu/news/cj_nr/2006/october/lw10bird.cfm?type=n.
Lori Wright | EurekAlert!
Scientists uncover the role of a protein in production & survival of myelin-forming cells
19.07.2018 | Advanced Science Research Center, GC/CUNY
NYSCF researchers develop novel bioengineering technique for personalized bone grafts
18.07.2018 | New York Stem Cell Foundation
A new manufacturing technique uses a process similar to newspaper printing to form smoother and more flexible metals for making ultrafast electronic devices.
The low-cost process, developed by Purdue University researchers, combines tools already used in industry for manufacturing metals on a large scale, but uses...
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
20.07.2018 | Power and Electrical Engineering
20.07.2018 | Information Technology
20.07.2018 | Materials Sciences | <urn:uuid:aefd834a-5f50-440c-a26b-64dfa2202c86> | 3.703125 | 1,435 | Content Listing | Science & Tech. | 34.414364 | 95,503,040 |
Imaging revealed interesting spaceflight-associated root morphologies. They needed to fix the tissues for further study back on Earth, but conventional fixation methods require separate fixatives depending on whether the sample is intended for molecular or morphological study.
This is a SEM image of Arabidopsis tissue processed using the new single fixation protocol developed by Schultz et al. Pictured is the adaxial leaf epidermis (3500x, scale bar = 8.57 ìm).
Credit: Image courtesy of Schultz et al.
If the scientists wanted to study how spaceflight affected patterns of gene expression central to morphological patterns of cell growth, they needed a fixation method that would allow them to study both perspectives.
Most scientists at work in the laboratory rely on protocols that have been developed without the need for restrictions on the amount of space, time, or reagents they use. For scientists conducting experiments in spaceflight, time and resources are strictly regulated and limited, and researchers must know in advance which protocols will maximize the usefulness of the data they collect.
University of Florida professors Anna-Lisa Paul and Robert Ferl and colleagues are collaborating with the National Aeronautics and Space Administration (NASA) to understand plant growth and development in spaceflight. Along with lead author and graduate student Eric Schultz, they have developed a single fixation protocol for use in space that allows plant material to be used for multiple experimental applications. Their new protocol for sample preparation was tested on Arabidopsis tissues harvested on the International Space Station and is described in the August issue of Applications in Plant Sciences (available for free viewing at http://www.bioone.org/doi/pdf/10.3732/apps.1300034).
Because of limitations in astronaut crew time and orbital resources, previous spaceflight fixation protocols were designated as either molecular or morphological, due to the separate fixatives required for each application. Tissues for morphologic study were fixed in 3% glutaraldehyde (or a similar solution), and tissues for molecular study were fixed in the tissue storage reagent RNAlater. RNAlater has not commonly been used as a morphologic fixative, as it can produce unclear images with high background staining.
The new method developed by Schultz et al. puts RNAlater-fixed samples through a desalination process to return them to a fresh-like state, and then uses low-temperature scanning electron microscopy (cryo-SEM) to preserve tissues for imaging. Because few laboratories have access to the necessary equipment for cryo-SEM, the authors tested and developed a protocol that emulates cryo-SEM using standard SEM equipment and, importantly, that results in minimal tissue damage.
Although it was developed to address specific constraints for spaceflight experiments, Paul notes that their new method is broadly applicable. "There are a lot of situations where biologists want to collect samples in extreme situations. In our case—a space vehicle orbiting the Earth."
The new protocol maximizes the amount of data obtained from a single sample and allows for the concomitant examination of both molecular and morphological features. Using a single fixation protocol, direct comparisons between changes in morphology and altered gene expression can be made. Such an analysis not only makes full use of samples and replicates but also enables a robust analysis of the relationship between heredity and development. "Putting two tools together, it is powerful to look at the morphology in conjunction with the genes that are being expressed," says Paul.
The new protocol boasts low costs and high accessibility, and has wide application to any situation where recovery of biological resources is limited. Notably, this includes researchers collecting and preserving samples in the field, where space for materials is at a premium. "In places where sampling is limited, difficult, or expensive, the use of preservatives allows for more routes to analysis," notes Ferl.
Applications in Plant Sciences (APPS) is a monthly, peer-reviewed, open access journal focusing on new tools, technologies, and protocols in all areas of the plant sciences. It is published by the Botanical Society of America (http://www.botany.org), a non-profit membership society with a mission to promote botany, the field of basic science dealing with the study and inquiry into the form, function, development, diversity, reproduction, evolution, and uses of plants and their interactions within the biosphere. The first issue of APPS published in January 2013; APPS is available as part of BioOne's Open Access collection (http://www.bioone.org/loi/apps).
For further information, please contact the APPS staff at firstname.lastname@example.org.
Beth Parada | EurekAlert!
O2 stable hydrogenases for applications
23.07.2018 | Max-Planck-Institut für Chemische Energiekonversion
Scientists uncover the role of a protein in production & survival of myelin-forming cells
19.07.2018 | Advanced Science Research Center, GC/CUNY
A new manufacturing technique uses a process similar to newspaper printing to form smoother and more flexible metals for making ultrafast electronic devices.
The low-cost process, developed by Purdue University researchers, combines tools already used in industry for manufacturing metals on a large scale, but uses...
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
23.07.2018 | Materials Sciences
23.07.2018 | Information Technology
23.07.2018 | Health and Medicine | <urn:uuid:c4582036-7dc0-45db-b947-8905ca145c1a> | 3.203125 | 1,551 | Content Listing | Science & Tech. | 31.768581 | 95,503,050 |
“From ocean measurements and by analysing climate simulations we can see there are changes in features of the ocean that cannot be explained by natural variability,” said CSIRO oceanographer Dr Gael Alory.
“These oceanic changes are almost certainly linked to changes in the heat structure of the atmosphere and have led to a rise in water temperatures in the sub-tropical Indian Ocean of around two degrees celsius.
“At the same time, we are seeing changes in ocean circulation in tropical regions as a result of a long-term weakening of the Pacific Ocean trade winds. This affects sea surface temperature in regions relevant to the source and distribution of rainfall across southern Australia,” Dr Alory said.
The research – by Dr Alory, his CSIRO Wealth from Oceans National Research Flagship colleague, Dr Gary Meyers, and CSIRO Marine and Atmospheric’s Dr Susan Wijffels – has recently appeared in the journal, Geophysical Research Letters. The paper examines trends in Indian Ocean temperatures over 40 years that can help scientists and resource managers understand fluctuations in rainfall patterns over southern Australia.
The research, contributing to the Australian Climate Change Science Program and partly funded by the South East Australia Climate Initiative, combined access to ocean observations using the volunteer ‘ships of opportunity’ program and a set of models used by scientists in developing the Intergovernmental Panel on Climate Change (IPCC) Fourth Assessment. Thanks to the operators and crew of commercial ships, Australian scientists have access to a regular series of ocean measurements to a depth of 800 metres across the Indian Ocean.
“The cooling is occurring between Australia and Indonesia where the Indonesian throughflow emerges into the Indian Ocean and is linked to the observed weakening of Pacific Ocean trade-winds,”The team’s key findings were:
a general warming of the ocean surface indicating the influence of rising atmospheric temperatures;
a strong warming (about 2°C over 40 years) between 40°S and 50°S down to a depth of 800 metres;
and, sub-surface cooling in the tropics due to deep waters rising closer to the surface.
Dr Alory says the research confirmed a long-held view that temperature changes in the Pacific and Indian oceans can be partly explained by the effect of the ‘Indonesian throughflow’ – a system of currents which transports water between the oceans through the maze of straits and passages in the Indonesian Archipelago.
“The cooling is occurring between Australia and Indonesia where the Indonesian throughflow emerges into the Indian Ocean and is linked to the observed weakening of Pacific Ocean trade-winds,” he says. The models also helped to explain trends in the subtropical Indian Ocean temperatures and changes in relevant ocean features. In this area, the deep-reaching warming is due to a strengthening of westerly winds drawing a southward shift in ocean current patterns. These findings are consistent with research in the South Atlantic and South Pacific ocean basins.
He said that the change in atmospheric conditions altering ocean temperatures – weakening of Pacific Ocean trade winds and strengthening of westerly winds – have been mostly attributed to human activity: the production of aerosols (tiny atmospheric particles), ozone depletion, and greenhouse gases. Strengthening westerlies are related to changes in the Southern Annular Mode – an atmospheric feature similar to the El Nino Southern Oscillation and considered the dominant influence on Southern Hemisphere atmospheric variability.
Dr Alory said climate models used in the IPCC Fourth Assessment show that changes in westerly wind patterns are expected to intensify in a global warming scenario and to accentuate the southward shift in sub-tropical ocean circulation patterns.
Dr. Gael Alory | 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
18.07.2018 | Life Sciences
18.07.2018 | Materials Sciences
18.07.2018 | Health and Medicine | <urn:uuid:5054853d-0131-4bd5-9c13-1e5aec463612> | 3.125 | 1,420 | Content Listing | Science & Tech. | 34.175749 | 95,503,116 |
A View from Brittany Sauser
ESA Satellite Reveals an Earthquake-Stricken Area's Recovery
Scientists used sophisticated radar technology to monitor the earth years after a natural disaster.
For the first time, scientists have been able to watch the deformation and recovery of Earth’s surface over the three-and-a-half years following a devastating earthquake. The researchers studied the aftermath of the 2003 Iranian Bam earthquake using a European Space Agency (ESA) satellite. Led by Eric Fielding of the Jet Propulsion Laboratory, California Institute of Technology, the scientists used a remote-sensing technique called interferometric synthetic aperture radar (InSAR) to create images and maps of the region over this period.
“The most important thing we found is that there is this elongated ditch, like a depression, that formed after the earthquake. It’s very shallow, only six centimeters after the 3.5 years, but it follows exactly along the area where the fault ruptured,” says Fielding. Understanding how damage zones respond to a quake may help predict how buried faults will behave, he adds. The findings were published today in the journal Nature.
Currently, little is known about what happens to Earth’s surface before or after an earthquake. Seismic monitoring using networked sensors, GPS, or ground surveys is only common in areas like California where the frequency of an event is high. In this study, the researchers used satellites to gather raw data and then processed the information into maps using InSAR, which pairs two radar images and measures the difference between every point (every 20 meters) in the images. The technique creates a very high resolution map so that scientists can see how the deformation caused by the earthquake is distributed.
The researchers have created 94 images thus far from four different tracks of data, says Fielding. “We need to understand the risks, so that we can eventually get to the level of predictions.”
The scientists are currently working with NASA on a new mission: to design a satellite that would allow them to do the same analysis for other earthquakes in different areas. The satellite needs to use different radar wavelengths that can penetrate areas with significant vegetation and capture images more frequently (Envisat acquired data every 35 days). The mission seems promising, especially since President Obama’s budget has allocated a good portion of money to NASA’s earth-science missions.
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:af6de0e0-8af8-4a15-9842-db21abfa2032> | 4.15625 | 525 | Truncated | Science & Tech. | 32.532548 | 95,503,130 |
A team of researchers at the
Energy Department's National Renewable Energy Laboratory (NREL) recently identified that single-walled carbon nanotube semiconductors can be beneficial for photovoltaic systems because the semiconductors are capable of transforming sunlight to electricity or fuels without losing a lot of energy.
(Credit: National Renewable Energy Laboratory)
The research is based on the Nobel Prize-winning work of Rudolph Marcus, who invented a basic tenet of physical chemistry that describes the rate at which an electron can travel from one chemical to another. However, the Marcus formulation has rarely been used to analyze photoinduced electron transfer for upcoming organic semiconductors like single-walled carbon nanotubes (SWCNT) capable of being used in organic PV devices.
After a photon is absorbed in organic PV devices, charges (holes and electrons) usually need to be segregated across an interface in order to have a prolonged life span that will enable collecting the charges as electrical current. The electron transfer event that develops these segregated charges is available with a potential energy loss because the molecules that are part of the process need to reorganize their bonds in a structural manner. This loss is known as reorganization energy, but the researchers discovered that a lot less energy was lost when SWCNT semiconductors were paired with fullerene molecules.
What we find in our study is this particular system -- nanotubes with fullerenes -- have an exceptionally low reorganization energy and the nanotubes themselves probably have very, very low reorganization energy. Tuning the driving force for exciton dissociation in single-walled carbon nanotube heterojunctions.
Jeffrey Blackburn, Senior Scientist, NREL
The paper has been published in the latest issue of Nature Chemistry. The co-authors of the paper are Rachelle Ihly, Kevin Mistry, Andrew Ferguson, Obadiah Reid, and Garry Rumbles from NREL, and Olga Boltalina, Tyler Clikeman, Bryon Larson, and Steven Strauss from Colorado State University.
Organic PV devices include an interface between a donor and an acceptor. In the case discussed here, the SWCNT is the donor as it provided an electron to the acceptor, which in this case is the fullerene. The researchers collaborated with colleagues at Colorado State University to use the expertise from each institution in developing donors and acceptors with energy levels that are highly tunable and well-defined. Fullerene acceptors were placed at CSU, and semiconducting SWCNT donors at NREL. This collaboration helped scientists from NREL to establish the fact that the electron transfer event occurred with less energy loss related to reorganization, highlighting the fact that it is possible to harvest solar energy in a more efficient manner. For this reason, SWCNT semiconductors are considered to be beneficial for PV applications.
The research was funded by Energy Department's Office of Science.
NREL is the U.S. Department of Energy's primary national laboratory for energy efficiency and renewable energy research and development. The Alliance for Sustainable Energy, LLC operates NREL for the Energy Department. | <urn:uuid:0d84a221-b965-4684-a851-d21c890cdbdf> | 3.21875 | 644 | News (Org.) | Science & Tech. | 13.27463 | 95,503,168 |
Formatting via SQL¶
Since the SQLite engine is running in-process with Excel, it can interact with Excel objects. The primary use case for this is to modify formatting.
As mentioned before, each table has a hidden
__address column which we can use to selectively apply formatting to rows.
Let's set the background color for movies that grossed more than $40M:
--first clear any previous formatting select ClearBackgroundColor('movies'); --apply new formatting select *, SetBackgroundColor(__address, 'Orange') from movies where gross > 400000000 order by __row asc
In the example, we're using the
ClearBackgroundColor function to clean any previously applied formatting, after which we apply formatting to the desired rows via the
It might seem strange to use a
SELECT statement to modify row formatting, but it's fairly easy to get used to, and there doesn't seem to be a more elegant way of doing it via SQL.
We can use the
SetBackgroundColor function to format cells as well. Here's an example of coloring cells based on their values:
select *, (case when value > 100000 then SetBackgroundColor(Address, 'blue') else SetBackgroundColor(Address, 'red') end) color from cells() where type = 'Double'
Here I'm formatting cells that contain a number in different colors, depending on their value. | <urn:uuid:293aa688-2d2e-4ad0-9705-f17d67ca159b> | 2.546875 | 289 | Documentation | Software Dev. | 32.139679 | 95,503,171 |
Researchers have recently discovered that dinosaurs had an innovative nesting style that may have led to the evolutionary success of modern birds. The study, published in the journal Plos One, details for the first time the link between dinosaur eggshell porosity and different nesting types, and shows how the prehistoric creatures’ nesting styles correlate with the way crocodiles and birds – the dinosaurs’ closest living relatives – nest.
Continue Reading Below
The question of how dinosaurs incubated their eggs has been debated among scientists for years.
“Nest structures are usually not preserved in the fossil record, making it difficult to determine if dinosaurs buried their eggs during incubation like crocodiles, or if they were incubated in more open nests as in brooding birds,” study co–author Kohei Tanaka of the University of Calgary told FoxNews.com. “There are many papers that seek the incubation method of dinosaurs, but our research is one of the most comprehensive studies in that it analyzes large datasets on the eggs of both living and fossil species.”
Related: Could humans and dinos coexist?
Tanaka and his team, under the supervision of dinosaur egg and nesting site expert Darla Zelenitsky, studied the fossilized eggshell porosity of 30 different dinosaur species before comparing them with the porosity of eggs belonging to 120 species of birds and crocodiles.
“Fossil eggs are more challenging to study because fossil specimens are often incomplete,” Tanaka said. “However, some of the microscopic features of the eggshell, such as porosity, are preserved, and can be used to infer the types of nests in dinosaurs in the absence complete nests.”
Continue Reading Below
Brooding birds’ eggs, which are incubated in open nests, have a low porosity while crocodile and megapode (also known as incubator or mound–building) bird eggs are highly porous and incubated in buried nests. Most dinosaurs, such as long–necked sauropods and carnivorous theropods, laid low porosity eggs, thus the researchers were able to conclude that they buried their eggs like the modern crocodile. The researchers also found that advanced theropods, including the bird–like maniraptorans, produced high porosity eggshells, hence their eggs were more likely to have been incubated in open nests like those of their closely related living birds.
“We were surprised that although previous studies on the eggs of oviraptorids suggested they were buried, our results reveal that their eggs were exposed similar to modern bird nests,” Tanaka said.
Still, the team did find evidence that the theropods did partly bury their eggs as well, leading them to conclude that it wasn’t until the arrival of modern birds that open nests with fully exposed eggs began to appear. This would indicate an evolutionary shift in nest and incubation styles between dinosaurs and birds. A switch from buried nests to open nesting and brooding would ensure that the eggs of advanced theropods (including birds) would be safe from ground predators, which may have played a large role in their evolutionary success.
Related: 'Superduck' dinosaur shows how dino crests evolved
“Our results suggest that the change in nesting style occurred in small meat-eating dinosaurs that are closely related to birds,” Tanaka explained. “To better understand dinosaur nesting styles, however, future discoveries of fossil eggs will hopefully fill in the gaps in the dinosaur family tree where eggs are currently unknown.”
The team is planning on using their research to answer other prehistoric nesting questions, such as the length of time it took for dinosaur eggs to hatch. | <urn:uuid:543d8b7f-e2c1-4cc8-b362-d5379b0ad176> | 4 | 763 | News Article | Science & Tech. | 22.867675 | 95,503,178 |
The programmer has two main concerns: correctness and efficiency. Thus far, this book has dealt mainly with the issue of correctness. This does not mean that efficiency is unimportant. When faced with any large task, it is usually best to put aside some of its aspects for a moment and to concentrate on the others, and that is what we have been doing. This important principle is called Separation of Concerns.
KeywordsEfficient Program Fixed Integer Expensive Operation Weak Precondition Efficiency Consideration
Unable to display preview. Download preview PDF. | <urn:uuid:b8b1a2db-4748-4a71-9500-6b604f8cb43c> | 2.703125 | 111 | Truncated | Software Dev. | 41.218182 | 95,503,181 |
The Washington-British Columbia Transboundary Climate-Connectivity Project was initiated to help address these challenges. The region spanning the border of Washington state, USA, and British Columbia, Canada, faces increasing development pressure and limited transboundary coordination of land and wildlife management, both of which may threaten habitat connectivity and limit the potential for wildlife movement in response to change. In addition, the effects of climate change may further reduce habitat connectivity, and species may need novel types of habitat connectivity to complete adaptive range shifts. This project paired scientists and practitioners from both sides of the border to collaboratively identify potential climate impacts and adaptation actions for transboundary habitat connectivity, using a diverse suite of case study species, a vegetation system, and a region.
Case study assessments revealed that climate change is likely to have significant implications for transboundary habitat connectivity. The adaptation actions identified to address potential impacts varied by case study, but fell into two general categories: those addressing potential climate impacts on existing habitat connectivity and those addressing novel habitat connectivity needs for climate-induced shifts in species ranges. In addition, project partners identified priority spatial locations for implementing these actions, as well as additional research needed to improve assessment of climate impacts and adaptation actions for habitat connectivity. | <urn:uuid:7263cbfc-beee-4e21-b23c-8db5247e7537> | 3.46875 | 247 | Knowledge Article | Science & Tech. | -15.053113 | 95,503,183 |
Excitement is mounting at the world’s largest proton smasher, where scientists are close to launching a superpowered hunt for particles that may change our understanding of the Universe.
Physicists and engineers are running the final checks after a two-year upgrade that nearly doubled the muscle of the Large Hadron Collider (LHC), which in 2012 unlocked the putative Higgs boson and, with it, a Nobel Prize.
Now it has its sights on finding exotic new particles in a previously-inaccessible realm that can sometimes resemble science fiction.
“The most exciting thing is we really don’t know what we are going to find,” said Rolf Landua of the European Organisation for Nuclear Research (CERN), which hosts the LHC.
Experiments at the collider seek to unlock clues as to how the Universe came into existence by studying fundamental particles, the building blocks of all matter, and the forces that control them.
During its next run, researchers will look for evidence of “new physics”. They will probe ‘supersymmetry’ — a theoretical concept informally dubbed Susy, seek explanations for enigmatic dark matter, and look for signs of extra dimensions.
In late March, beams containing billions of protons travelling at 99.9 percent the speed of light will shoot through the collider’s 27-kilometre (17-mile) ring-shaped tunnel straddling the Franco-Swiss border.
By about the end of May or early June, the mighty machine should be calibrated and start its long-awaited proton collisions — brief but super-intense smashups recorded in four labs dotted around the ring.
Physicists scour the debris for clues of new, hopefully exotic, sub-atomic particles.
“The most important thing which we would like to find is a new type of particle which could help to explain what this mysterious dark matter is,” said Landua.
Ordinary, visible matter comprises only about four percent of the known Universe.
There is believed to be five to 10 times more dark matter, which together with equally mysterious dark energy accounts for 96 percent of the cosmos.
– ‘Fixing’ the Standard Model –
Fresh from its Higgs exploit, the LHC was shut as scheduled in 2013 to boost its collision capacity to 13 teraelectronvolts (TeV) — 6.5 TeV for each of the two counter-rotating beams that zip around the ring.
“Thirteen TeV will be a new record, which will open the door hopefully for new physics, new discoveries,” operator Mirko Pojer said at the bustling CERN control centre.
“LHC Run 2 will certainly help the physicists to better explain our Universe.”
The collider’s previous highest power was 8 TeV reached in 2012.
“I am pretty sure now with the new energy in the accelerator we will discover something,” said Frederick Bordry, CERN director for accelerators and technology.
“By increasing the energy, the potential of discovery is higher by… maybe two orders of magnitude,” or a hundred-fold, he said.
During its second three-year run, the LHC will seek to fill gaps in the “Standard Model” — the mainstream theory of how our visible Universe is constructed.
The model doesn’t explain dark matter or dark energy — and seems incompatible with the theory of gravity.
Leading the pack of additional theories, “Susy” postulates the existence of a more massive, “supersymmetric” sibling for every known Standard Model particle.
This may explain dark matter, which is observable only through its gravitational effect on visible matter — holding galaxies together, for example.
Scientists believe the LHC must now be powerful enough to find supersymmetric particles, if they exist.
– Higgses galore? –
“Susy is super beautiful and would fix the Standard Model in many ways,” said Rebeca Suarez of the LHC’s Compact Muon Solenoid (CMS) experiment.
“But honestly, the hopes of supersymmetry are really low at the moment… we have really looked. Lighter particles of supersymmetry should have been accessible already.
“We are losing hope more every day about it. But there were also those losing hope of finding the Higgs and in the end we found it!”
The Higgs boson, theorised to confer mass on matter, was the last undiscovered particle predicted by the Standard Model.
Supersymmetry postulates there must be additional types of Higgs.
“Something very important will be to measure really well the Higgs boson that we have, to finally characterise it as a Standard Model particle,” said Suarez.
“Any tiny deviation that we may find in the properties of the Higgs boson or any other Standard Model particle that does not follow the predictions could be a clear sign of new phenomena.”
With the upgrade, the LHC can potentially be cranked up to a maximum 14 TeV, but even this may not be enough to find explanations for the strange phenomenon of dark matter, she said. A further, anticipated update may be required for that.
“To find extra Higgses would be nice, to find extra anything would be really great,” said Suarez.
“If there is nothing, also it is interesting,” she added, adding in all earnestness: “But of course to me, that is the worst-case scenario… It would be the worst thing to happen.” | <urn:uuid:6cb1eeea-4715-4846-b8ef-053c442fb0a5> | 2.65625 | 1,197 | News Article | Science & Tech. | 45.105592 | 95,503,184 |
Common name: Florida applesnail
available through www.itis.gov
Identification: This species is the largest freshwater gastropod in North America (Burch 1982). It is globose in shape, body whorls are wide, spire is depressed, and the aperature is narrowly oval (Burch 1982). They are brown in color and have a striped pattern.
Size: 60 mm in length and width (Burch 1982)
Native Range: Central and southern Florida (Thompson 1984); Cuba; Hispanola (Dundee 1974).
Interactive maps: Point Distribution Maps
Puerto Rico &
Table 1. States with nonindigenous occurrences, the earliest and latest observations in each state, and the tally and names of HUCs with observations†. Names and dates are hyperlinked to their relevant specimen records. The list of references for all nonindigenous occurrences of Pomacea paludosa are found here.
Table last updated 5/25/2018
† Populations may not be currently present.
Ecology: Tropical species. Amphibious, but can survive dry seasons (Burch1982). Applesnails have both gills and lungs.
Means of Introduction: Unknown
Impact of Introduction: Unknown
References: (click for full references)
Burch, J. B. 1982. North American freshwater snails.Walkerana 1(4):217-365.
Dundee, D. S. 1974. Catalog of introduced molluscs of eastern North America (north of Mexico). Sterkiana 55:1-37.
Thompson, F.G. 1984. The freshwater snails of Florida: a manual for identification. University of Florida Press, Gainesville, Florida, 94 pp.
Revision Date: 4/24/2006
Benson, A.J., 2018, Pomacea paludosa: U.S. Geological Survey, Nonindigenous Aquatic Species Database, Gainesville, FL, https://nas.er.usgs.gov/queries/FactSheet.aspx?speciesID=985, Revision Date: 4/24/2006, Access Date: 7/16/2018
This information is preliminary or provisional and is subject to revision. It is being provided to meet the need for timely best science. The information has not received final approval by the U.S. Geological Survey (USGS) and is provided on the condition that neither the USGS nor the U.S. Government shall be held liable for any damages resulting from the authorized or unauthorized use of the information. | <urn:uuid:01584477-6efe-4aec-832c-6e139476f826> | 2.8125 | 532 | Structured Data | Science & Tech. | 53.172132 | 95,503,195 |
+44 1803 865913
By: BGD Bartley
342 pages, 32 pp col plates, figs
The cacao (Theobroma cacao) plant is an important Neo-Tropical species whose natural habitat is the Amazon basin. Over the last 30 years there has been a considerable geographical expansion in the availability of cacao genetic resources. As a result the plant has a rich genetic diversity that exists at two levels: that of the primitive populations in the area of original distribution of the species, and that of the derived cultivated populations.
This book provides a comprehensive review of our current knowledge of the diversity of the species. It starts by examining the diversity and inheritance of the characteristics of primitive populations in the Amazonian and Caribbean regions. It then looks at the evolution of diversity within cultivated populations first in South America and around the Caribbean, and then beyond the Americas. The book describes the inter-relationships between populations based on morphological and molecular markers. It also examines the conservation of genetic resources and how these genetic resources can be utilized to produce new cultivars.
There are currently no reviews for this book. Be the first to review this book!
Your orders support book donation projects
They [the books] arrived in wonderful condition and it was a joy to see how well they were protected.
Search and browse over 110,000 wildlife and science products
Multi-currency. Secure worldwide shipping
Wildlife, science and conservation since 1985 | <urn:uuid:f1d9b8ec-9074-42da-a8d3-5bf49e18aed2> | 3.578125 | 297 | Product Page | Science & Tech. | 29.887761 | 95,503,199 |
Voyager Encounters Jupiter
Publisher: National Aeronautics and Space Administration 1979
Number of pages: 48
Passing by Jupiter and its complex satellite system in 1979, the Voyager spacecraft have collected and returned to Earth an enormous amount of data and information that may prove to be a keystone in understanding our solar system. This publication provides an early look at the Jovian planetary system and contains a selected sample from the more than 30,000 images collected during this phase of the Voyager mission.
Home page url
Download or read it online for free here:
by Thomas P. Hansen - NASA
The 1964 Lunar Orbiter program consisted of the investigation of the Moon by five unmanned spacecraft. Its objective was to obtain detailed photographs of the Moon. This document presents information on the location and coverage of all photographs.
by Michael H. Carr - NASA
The knowledge gained through space exploration is leading to the new science of comparative planetology. This book outlines the geologic history of the terrestrial planets in light of recent exploration and the revolution in geologic thinking.
by Elbert A. King - The Lunar and Planetary Institute
The origins of chondrules are fundamental problems of most stony meteorites and some planetary surface samples. The contents of this volume are designed to provide the reader with a broad overview of current ideas in this area of research.
by Don E. Wilhelms - University of Arizona Press
Don Wilhelms was a member of the Apollo Scientific Team. In this book he describes his role, along with his colleagues, during the Apollo explorations of the Moon. He presents a brief history of the theories associated with the origin of the moon. | <urn:uuid:2a7e7a37-fdf9-46d9-adfa-4810df259830> | 3.078125 | 341 | Content Listing | Science & Tech. | 35.333571 | 95,503,212 |
Security Best Practices for C++
This article contains information about security tools and practices. Using them does not make applications immune from attack, but it makes successful attacks less likely.
Visual C++ Security Features
These security features are built into the Visual C++ compiler and linker:
/guard (Enable Control Flow Guard)
Causes the compiler to to analyze control flow for indirect call targets at compile time, and then to insert code to verify the targets at runtime.
/GS (Buffer Security Check)
Instructs the compiler to insert overrun detection code into functions that are at risk of being exploited. When an overrun is detected, execution is stopped. By default, this option is on.
/SAFESEH (Image has Safe Exception Handlers)
Instructs the linker to include in the output image a table that contains the address of each exception handler. At run time, the operating system uses this table to make sure that only legitimate exception handlers are executed. This helps prevent the execution of exception handlers that are introduced by a malicious attack at run time. By default, this option is off.
/NXCOMPAT, /NXCOMPAT (Compatible with Data Execution Prevention)
These compiler and linker options enable Data Execution Prevention (DEP) compatibility. DEP guards the CPU against the execution of non-code pages.
/analyze (Code Analysis)
This compiler option activates code analysis that reports potential security issues such as buffer overrun, un-initialized memory, null pointer dereferencing, and memory leaks. By default, this option is off. For more information, see Code Analysis for C/C++ Overview.
/DYNAMICBASE (Use address space layout randomization)
This linker option enables the building of an executable image that can be loaded at different locations in memory at the beginning of execution. This option also makes the stack location in memory much less predictable.
The C Runtime Library (CRT) has been augmented to include secure versions of functions that pose security risks—for example, the unchecked
strcpy string copy function. Because the older, nonsecure versions of these functions are deprecated, they cause compile-time warnings. We encourage you to use the secure versions of these CRT functions instead of suppressing the compilation warnings. For more information, see Security Features in the CRT.
SafeInt Library helps prevent integer overflows and other exploitable errors that might occur when the application performs mathematical operations. The
SafeInt library includes the SafeInt Class, the SafeIntException Class, and several SafeInt Functions.
SafeInt class protects against integer overflow and divide-by-zero exploits. You can use it to handle comparisons between values of different types. It provides two error handling policies. The default policy is for the
SafeInt class to throw a
SafeIntException class exception to report why a mathematical operation cannot be completed. The second policy is for the
SafeInt class to stop program execution. You can also define a custom policy.
SafeInt function protects one mathematical operation from an exploitable error. You can use two different kinds of parameters without converting them to the same type. To protect multiple mathematical operations, use the
A checked iterator enforces container boundaries. By default, when a checked iterator is out of bounds, it generates an exception and ends program execution. A checked iterator provides other levels of response that depend on values that are assigned to preprocessor defines such as _SECURE_SCL_THROWS and _ITERATOR_DEBUG_LEVEL. For example, at _ITERATOR_DEBUG_LEVEL=2, a checked iterator provides comprehensive correctness checks in debug mode, which are made available by using asserts. For more information, see Checked Iterators and _ITERATOR_DEBUG_LEVEL.
Code Analysis for Managed Code
Code Analysis for Managed Code, also known as FxCop, checks assemblies for conformance to the.NET Framework design guidelines. FxCop analyzes the code and metadata in each assembly to check for defects in the following areas:
Windows Application Verifier
The Application Verifier (AppVerifier) can help you identify potential application compatibility, stability, and security issues.
The AppVerifier monitors how an application uses the operating system. It watches the file system, registry, memory, and APIs while the application is running, and recommends source-code fixes for issues that it uncovers.
You can use the AppVerifier to:
Test for potential application compatibility errors that are caused by common programming mistakes.
Examine an application for memory-related issues.
Identify potential security issues in an application.
The AppVerifier is part of the Application Compatibility Toolkit, which is available from the Application Compatibility on the TechNet web site.
Windows User Accounts
Using Windows user accounts that belong to the Administrators group exposes developers and--by extension--customers to security risks. For more information, see Running as a Member of the Users Group and How User Account Control (UAC) Affects Your Application.
Guidance for Speculative Execution Side Channels
For information about how to indentify and mitigate against speculative execution side channel hardware vulnerabilities in C++ software, see C++ Developer Guidance for Speculative Execution Side Channels. | <urn:uuid:5dcc40fa-5b0b-42ed-8b7d-3309d4b08c51> | 3.0625 | 1,096 | Documentation | Software Dev. | 15.459873 | 95,503,219 |
— Ice sheets are like bulldozers. As they grow, they push rocks, boulders, clams, fossils and other debris into piles called moraines.
Credit: Jason Briner
Shells from Greenland. By dating fossils like these, scientists have come up with a new technique for determining when glaciers were smaller than they are today.
— By dating ancient clams in moraines, scientists have come up with a new technique for determining when glaciers were smaller than they are today.
— The technique suggests that the Greenland Ice Sheet was at its smallest point in recent history 3-5,000 years ago — information that could improve our understanding of how ice responds to climate change.
Think Greenland’s ice sheet is small today?
It was smaller — as small as it has ever been in recent history — from 3-5,000 years ago, according to scientists who studied the ice sheet’s history using a new technique they developed for interpreting the Arctic fossil record.
“What’s really interesting about this is that on land, the atmosphere was warmest between 9,000 and 5,000 years ago, maybe as late as 4,000 years ago. The oceans, on the other hand, were warmest between 5-3,000 years ago,” said Jason Briner, PhD, University at Buffalo associate professor of geology, who led the study.
“What it tells us is that the ice sheets might really respond to ocean temperatures,” he said. “It’s a clue to what might happen in the future as the Earth continues to warm.”
The findings appeared online on Nov. 22 in the journal Geology. Briner’s team included Darrell Kaufman, an organic geochemist from Northern Arizona University; Ole Bennike, a clam taxonomist from the Geological Survey of Denmark and Greenland; and Matthew Kosnik, a statistician from Australia’s Macquarie University.
The study is important not only for illuminating the history of Greenland’s ice sheet, but for providing geologists with an important new tool: A method of using Arctic fossils to deduce when glaciers were smaller than they are today.
Scientists have many techniques for figuring out when ice sheets were larger, but few for the opposite scenario.
“Traditional approaches have a difficult time identifying when ice sheets were smaller," Briner said. "The outcome of our work is that we now have a tool that allows us to see how the ice sheet responded to past times that were as warm or warmer than present — times analogous to today and the near future."
The technique the scientists developed involves dating fossils in piles of debris found at the edge of glaciers.
To elaborate: Growing ice sheets are like bulldozers, pushing rocks, boulders and other detritus into heaps of rubble called moraines.
Because glaciers only do this plowing when they're getting bigger, logic dictates that rocks or fossils found in a moraine must have been scooped up at a time when the associated glacier was older and smaller.
So if a moraine contains fossils from 3,000 years ago, that means the glacier was growing — and smaller than it is today — 3,000 years ago.
This is exactly what the scientists saw in Greenland: They looked at 250 ancient clams from moraines in three western regions, and discovered that most of the fossils were between 3-5,000 years old.
The finding suggests that this was the period when the ice sheet’s western extent was at its smallest in recent history, Briner said.
“Because we see the most shells dating to the 5-3000-year period, we think that this is when the most land was ice-free, when large layers of mud and fossils were allowed to accumulate before the glacier came and bulldozed them up,” he said.
Because radiocarbon dating is expensive, Briner and his colleagues found another way to trace the age of their fossils.
Their solution was to look at the structure of amino acids — the building blocks of proteins — in the fossils of ancient clams. Amino acids come in two orientations that are mirror images of each other, known as D and L, and living organisms generally keep their amino acids in an L configuration.
When organisms die, however, the amino acids begin to flip. In dead clams, for example, D forms of aspartic acid start turning to L’s.
Because this shift takes place slowly over time, the ratio of D’s to L’s in a fossil is a giveaway of its age.
Knowing this, Briner’s research team matched D and L ratios in 20 Arctic clamshells to their radiocarbon-dated ages to generate a scale showing which ratios corresponded with which ages. The researchers then looked at the D and L ratios of aspartic acid in the 250 Greenland clamshells to come up with the fossils’ ages.
Amino acid dating is not new, but applying it to the study of glaciers could help scientists better understand the history of ice — and climate change — on Earth.
The study was funded by the National Geographic Society and U.S. National Science Foundation.
New research calculates capacity of North American forests to sequester carbon
16.07.2018 | University of California - Santa Cruz
Scientists discover Earth's youngest banded iron formation in western China
12.07.2018 | University of Alberta
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
17.07.2018 | Information Technology
17.07.2018 | Materials Sciences
17.07.2018 | Power and Electrical Engineering | <urn:uuid:69ddee02-5849-438a-addc-8c54159572b9> | 4.65625 | 1,717 | Content Listing | Science & Tech. | 48.780121 | 95,503,232 |
Beyond Einstein is NASA's research roadmap for five proposed mission areas to study the most compelling questions at the intersection of physics and astronomy. The committee that wrote the report added that another proposed mission to detect gravitational waves using the Laser Interferometer Space Antenna (LISA) should eventually become the flagship mission of Beyond Einstein, given that it is likely to provide an entirely new way to observe the universe. However, LISA needs more testing before a launch can be planned, whereas the Joint Dark Energy Mission is ready now for a competitive selection of mission concept proposals.
Prompted by Congress and the Office of Science and Technology Policy, NASA and DOE asked the committee to assess the five proposed mission areas and recommend one for first development and launch. NASA’s Beyond Einstein program, set to begin in 2009, is comprised of two astronomical observatories, Constellation-X and LISA, as well as a series of probes: the Inflation Probe (IP), the Black Hole Finder Probe (BHFP), and JDEM.
"All of the mission areas in the Beyond Einstein program have the potential to fundamentally alter our understanding of the universe," said committee co-chair Charles F. Kennel, distinguished professor and director of the Environment and Sustainability Initiative at the University of California, San Diego. "But JDEM will provide direct insight into a key Beyond Einstein science question, and is the most technically feasible option for immediate development."
Of particular interest to researchers is whether the acceleration of the expansion of the universe varies over time. So far, three specific mission plans have been studied in this area: the Supernova Acceleration Probe (SNAP), the Dark Energy Space Telescope (DESTINY), and the Advanced Dark Energy Physics Telescope (ADEPT), but the eventual JDEM could be any one of the three or be based on a different option altogether. The committee found that the underlying technology for a dark energy mission is, for the most part, in the prototype phase, and will require less development than most of the other missions. The potential gains for JDEM also outweigh its scientific risks, such as the possibility that the mission may not provide substantial insight beyond that provided by telescopes on the ground. The report recommends that NASA and DOE proceed immediately with a competition for mission proposals that will investigate the nature of dark energy with high precision.
The committee also recommended that NASA invest additional Beyond Einstein funds in technology development of the LISA program. LISA, which is funded through a partnership between NASA and the European Space Agency (ESA), is designed to detect gravitational waves arising from, among other phenomena, the merging of black holes. The committee found that LISA will open up new ways of observing the universe, but must await results from ESA's "LISA Pathfinder" mission first. Scheduled for launch in 2009, LISA Pathfinder will test many of the new technologies required for the LISA program. Yet, some critical technologies, such as extended use of micro-Newton thruster technology, will not be tested. The report recommends that the development of these technologies should be a high priority for the Beyond Einstein program.
The report indicates that the three elements of Beyond Einstein that are not being recommended for immediate implementation are still important endeavors that should receive continued support. The committee found that because the Constellation-X mission is a general-purpose x-ray observatory capable of broad contributions to astrophysics, it should be funded and assessed in a broader context than the Beyond Einstein program. The Black Hole Finder Probe and Inflation Probe missions will also make important scientific contributions; however, because of scope and technical readiness issues, they fell behind JDEM and LISA. The committee recommended that Constellation-X, Black Hole Finder Probe, and Inflation Probe receive continued support to prepare them for the next decadal survey of astronomy and astrophysics.
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 | Materials Sciences
18.07.2018 | Life Sciences
18.07.2018 | Health and Medicine | <urn:uuid:2619c407-93c8-4fab-b48e-5a82868869ed> | 3.625 | 1,415 | Content Listing | Science & Tech. | 34.00556 | 95,503,245 |
BLACK holes are mysterious and terrifying – and we’ve got a simple guide to how they work.
We explain what a black hole is, why they exist, and how the late Professor Stephen Hawking helped us better understand how they work.
What is a black hole?
A black hole is a region of space where absolutely nothing can escape.
That’s because they have extremely strong gravitational effects, which means once something goes into a black hole, it can’t come back out.
They get their name because even light can’t escape once it’s been sucked in – which is why a black hole is completely dark.
What is an event horizon?
There has to be a point at which you’re so close to a black hole you can’t escape.
Otherwise literally everything in the universe would have been sucked into one.
The point at which you can no longer escape from a black hole’s gravitational pull is called the event horizon.
The event horizon varies between different black holes, depending on their mass and size.
What is a singularity?
The gravitational singularity is the very centre of a black hole.
It’s a one-dimensional point that contains an incredibly large mass in an infinitely small space.
At the singularity, space-time curves infinitely and the gravitational pull is infinitely strong.
Conventional laws of physics stop applying at this point.
What happens if you fall into a black hole?
We don’t really know for sure what actually happens when you enter a black hole.
The most popular theory is that objects become massively stretched out and lose all dimensional form.
And then, you’ll disappear completely. So don’t try it, basically.
How are black holes created?
Most black holes are made when a supergiant star dies.
This happens when stars run out of fuel – like hydrogen – to burn, causing the star to collapse.
When this happens, gravity pulls the centre of the star inwards quickly, and collapses into a tiny ball.
It expands and contracts until one final collapse, causing part of the star to collapse inward thanks to gravity, and the rest of the star to explode outwards.
The remaining central ball is extremely dense, and if it’s especially dense, you get a black hole.
What did Professor Stephen Hawking teach us about black holes?
Professor Stephen hawking discovered that if there was a Big Bang that created the universe, it must have started from a singularity.
He also found that black holes radiate energy and gradually lose mass. The energy is called Hawking radiation.
The genius professor predicted the existence of mini-black holes around the time of the Big Bang, too.
And he also helped resolve the black hole information paradox –the complicated physics around how black holes can erase information and retain it at the same time.
The problem was that black holes appear to destroy everything, but the laws of physics suggest you can’t completely destroy something – the raw bits should still be retained.
MOST READ IN TECH
20,000 TREES UNDER THE SEAMysterious ancient underwater forest offers a chilling glimpse of Earth's grim future, scientists say
So in 2016, Hawking suggested that black holes have a halo of “soft hair” around them, which carries a signature pattern of things swallowed and destroyed by black holes.
This means that things that enter black holes are lost forever, but also retained forever too.
Did you realise how interested Professor Stephen Hawking was in black holes? Let us know in the comments.
We pay for your stories! Do you have a story for The Sun Online news team? Email us at email@example.com or call 0207 782 4368 . We pay for videos too. Click here to upload yours. | <urn:uuid:bb6b29bf-3498-4979-94f8-1f70dfe301a6> | 3.84375 | 804 | Truncated | Science & Tech. | 56.387238 | 95,503,262 |
평점 : 0 . 0
There are lots of introductory C books, but this is the first one that has the no-nonsense, practical approach that has made Nutshell Handbooks(R) famous.
C programming is more than just getting the syntax right. Style and debugging also play a tremendous part in creating programs that run well and are easy to maintain. This book teaches you not only the mechanics of programming, but also describes how to create programs that are easy to read, debug, and update.
Practical rules are stressed. For example, there are fifteen precedence rules in C (&& comes before || comes before ?:). The practical programmer reduces these to two:
Multiplication and division come before addition and subtraction.
Put parentheses around everything else.
Contrary to popular belief, most programmers do not spend most of their time creating code. Most of their time is spent modifying someone else's code. This books shows you how to avoid the all-too-common obfuscated uses of C (and also to recognize these uses when you encounter them in existing programs) and thereby to leave code that the programmer responsible for maintenance does not have to struggle with. Electronic Archaeology, the art of going through someone else's code, is described.
This third edition introduces popular Integrated Development Environments on Windows systems, as well as UNIX programming utilities, and features a large statistics-generating program to pull together the concepts and features in the language.
--- FROM THE PUBLISHER
Daum 책은 통신판매중개자로서 상품주문, 배송 및 환불의 의무와 책임은 각 판매업체에 있습니다. 위 내용에 대한 저작권 및 법적 책임은 자료제공사 또는 글쓴이에 있으며 Kakao의 입장과 다를 수 있습니다.
사업자등록번호 : 120-81-47521|통신판매업신고번호 : 제 2015-제주아라-0032호
공동대표이사 여민수, 조수용|주소 : 제주특별자치도 제주시 첨단로 242㈜카카오|대표번호 : 1577-3321 | <urn:uuid:768962c6-5401-4f00-8c66-44fe3cc28cdc> | 2.984375 | 739 | Product Page | Software Dev. | 63.578114 | 95,503,273 |
- Open Access
The Upper Atmosphere and Plasma Imager/the Telescope of Visible Light (UPI/TVIS) onboard the Kaguya spacecraft
© The Society of Geomagnetism and Earth, Planetary and Space Sciences (SGEPSS); The Seismological Society of Japan; The Volcanological Society of Japan; The Geodetic Society of Japan; The Japanese Society for Planetary Sciences; TERRAPUB. 2009
Received: 9 August 2009
Accepted: 11 September 2009
Published: 18 January 2010
The Upper Atmosphere and Plasma Imager (UPI) was placed in a lunar orbit in order to study both the Moon and Earth. The UPI consists of two telescopes: a Telescope of Extreme Ultraviolet (TEX) and a Telescope of Visible Light (TVIS), which are both mounted on a two-axis gimbals system. The TVIS is equipped with fast catadioptric optics and a high-sensitivity CCD to image swift aurora and dark airglow in the terrestrial upper atmosphere. TVIS has a field-of-view equivalent to the Earth’s disk as seen from the Moon. The spatial resolution is about 30 km × 70 km on the Earth’s surface at auroral latitudes. The observation wavelengths can be changed by selecting different bandpass filters. Using the images of the northern and southern auroral ovals taken by TVIS, the intensities and shapes of the conjugate auroras will be quantitatively compared. Using the airglow imaging, medium- and large-scale ionospheric disturbances will be studied. In this paper, the instrumental design and performance of TVIS are presented. | <urn:uuid:f768e44c-bfb4-41e4-a08e-aac310664e7a> | 2.578125 | 350 | Academic Writing | Science & Tech. | 29.812356 | 95,503,282 |
All Species & Projects
Tulip Test Gardens
Sunlight & Seasons
Weather and Songbirds
Symbolic Monarch Migration
Monarchs and Their Predators in Mexico
Protected by Poison Milkweed contains a chemical that is poisonous to many animals — but not to monarchs. Monarchs eat milkweed when they are caterpillars. The body of the adult monarch contains the poison it ate as a caterpillar. Most of the poison is stored in the cuticle (skin) of the butterfly’s abdomen.
Identifying Enemies Dr. Lincoln Brower and his research teams worked for many years to identify the monarch’s enemies in the winter sanctuaries. The scientists discovered three main predators. Each predator has its own method of eating a butterfly, so leaves clues that reveal its identity.
Mice Eat Monarchs Mice feed at night. They will eat living, dying, and recently dead butterflies that they find on the ground. There are 4 species of mice in the area, but only one is known to feed heavily on monarchs. The Black-eared mouse (Peromyscus melanotis) is evidently not hurt by the poison. One mouse can eat about 37 monarchs a night. Mice leave a pile of wings on the ground.
Orioles Eat Monarchs Black-backed Orioles prey on monarchs. The Orioles avoid the poison by not eating the cuticle where most of the toxins are stored. An oriole uses its sharp beak to slice the cuticle open, and then eats the fat inside. The birds feed on monarchs in the morning and evening, when the butterflies are too cold to fly.
Grosbeaks Eat Monarchs It's easy to tell when a Black-headed Grosbeak ate a butterfly. The monarch's entire abdomen is missing. Grosbeaks do eat the cuticle. However, they selectively eat male monarchs who have 30% less toxins than females have. There are 37 bird species in the region that eat insects, but only the Oriole and Grosbeak prey on the monarchs.
The Impact of Predators Millions of monarchs are eaten in Mexico. The ground under a butterfly colony is peppered with wings by the end of the winter. More than 15% of the entire overwintering population is killed by predators in a typical year, according to one estimate.
Safety in Numbers Beyond protection from poison, monarchs have other ways to defend themselves. "Forming a colony is clearly an anti-predator strategy," says Dr. Brower. "The probability of any one butterfly being killed is lower if the individuals aggregate, or group together."
Climbing and Flying to Safety Monarchs are vulnerable when they’re on the ground and cold. They can’t crawl until their muscles reach 41°F or fly until they reach 55°F. Monarchs will struggle to fly to the trees — or crawl to the nearest twig — for safety.
Quiet and Camouflaged When at rest, monarchs are hidden in the forest by their stillness, their silence, and their coloration. The bright orange wings are closed. The wings’ undersides are dull and match the bark and lichens perfectly.
Silent Self-Defense Millions of motionless monarchs appear vulnerable in the colony, but the butterflies can defend themselves powerfully and effectively.
Who are the monarch's predators in Mexico and how do the butterflies defend themselves?
© Journey North. All rights reserved. | <urn:uuid:03146e20-4ebe-4c27-9cc3-8e912dc12f5b> | 3.640625 | 718 | Knowledge Article | Science & Tech. | 54.585172 | 95,503,317 |
Constraints and Data Relations
In chapter 3, you encountered constraints and data relations. In this chapter, we discuss constraints and data relations in more detail. First, we start this chapter with a discussion of constraints and how ADO.NET constraint objects maintain data integrity. Second, we discuss data relations. An object that encapsulates a data relationship may be a new concept for many programmers.
KeywordsData Relation Extend Property Unique Constraint Constraint Class Default Action
Unable to display preview. Download preview PDF. | <urn:uuid:50524216-cfc6-4d82-abf6-12a086aac4c3> | 2.59375 | 108 | Truncated | Software Dev. | 40.935903 | 95,503,319 |
In order to fully understand the dynamics during a chemical reaction, scientists must be able to study all movements of atoms and molecules on their basic time scale.
Molecules rotate in the range of picoseconds (10-12 s), their atoms vibrate in the range of femtoseconds (10?15 s), and the electrons move in the range of attoseconds (10-18 s). ETH professor Hans Jakob Wörner and his group have now succeeded in generating the world's shortest laser pulse with a duration of only 43 attoseconds.
More generally speaking, this laser pulse is the shortest controlled event that has ever been created by humans. The researchers can now observe in high detail how electrons move within a molecule or how chemical bonds are formed.
Breaking down transition states
Starting from an infrared laser, the researchers generate a soft X-ray laser pulse with a very large spectral bandwidth. As a result, various elements including phosphorus and sulphur can be directly observed by exciting their inner-shell electrons. Both elements are present in biomolecules, and it is now possible to observe them with unprecedented time resolution.
But what is the advantage of being able to observe the reaction steps now with even higher resolution? "The faster a charge transfer can take place, the more efficiently a reaction can proceed", says Prof. Wörner. The human eye for example is very efficient when it comes to converting photons into nerve signals.
In rhodopsin, a visual pigment in the retina, the photosensitive molecule retinal is prearranged in such a way that its structure can change extremely fast through the absorption of only a single photon. This enables the visual process even in twilight. A much slower reaction would render vision impossible, because the energy of the photon would be converted to heat in only a few picoseconds.
Attosecond spectroscopy could contribute to the development of more efficient solar cells since it is now for the first time possible to follow the process of excitation through sunlight up to the generation of electricity step by step. A detailed understanding of the charge transfer pathway could help optimizing the efficiency of the next generation of photosensitive elements.
Optical manipulation of the reaction process
Attosecond laser spectroscopy is not only suitable for mere observation, Prof. Wörner explains. Chemical reactions can also be directly manipulated: Using a laser pulse can alter the course of a reaction - even chemical bonds can be broken by stopping the charge shift at a certain location in the molecule. Such targeted interventions in chemical reactions have not been possible until now, since the time scale of electron movement in molecules was previously unreached.
The group of Prof. Wörner is already working on the next generation of even shorter laser pulses. These will make it possible to record even more detailed images, and thanks to a wider X-ray spectrum even more elements can be probed than before. Soon it will be possible to follow the migration of electrons in more complex molecules with an even higher time resolution.
Gaumnitz T, Jain A, Pertot Y, Huppert M, Jordan I, Ardana-Lamas F, Wörner HJ. Streaking of 43-attosecond soft-X-ray pulses generated by a passively CEP-stable mid-infrared driver. Optics Express, Vol. 25, Issue 22 (2017) doi: 10.1364/OE.25.027506
Dr. Hans Jakob Wörner | 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.
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:7369082c-fa7d-4f30-a6b1-550c2dc3b6da> | 4 | 1,366 | Content Listing | Science & Tech. | 40.657144 | 95,503,328 |
Seismicity is a measure which encompasses earthquake occurrences, mechanisms, and magnitude at a given geographical location. As such it summarizes a region's seismic activity. The term was coined by Beno Gutenberg and Charles Francis Richter in 1941. Seismicity is studied by geophysicists.
Calculation of seismicity
Seismicity is quantitatively computed. Generally the region under study is divided in equally sized areas defined by latitude and longitude and the interior of the Earth is divided into various depth intervals on account of Earth's layering: Up to 50 km depth, 50–300 km, and > 300 km.
The usual formula to calculate seismicity is:
- : is the energy of a single seismic event (i.e., earthquake);
- : interval of latitude;
- : interval of longitude
- : interval of the hypocenter;
- : interval of the time of the seismic event.
- The result is seismicity as energy per cubic unit.
- ^ Stacey, Frank (2008). Physics of the Earth (4 ed.). Cambridge, UK: CUP.
- ^ Schneider, Götz (2004). Erdbeben. Eine Einführung für Geowissenschaftler und Bauingenieure. Hamburg, Germany: Springer.
This page is based on a Wikipedia article written by authors
Text is available under the CC BY-SA 3.0 license; additional terms may apply.
Images, videos and audio are available under their respective licenses. | <urn:uuid:a99bae79-5792-4488-bea8-d1ac2103ae39> | 4.15625 | 315 | Knowledge Article | Science & Tech. | 40.546866 | 95,503,338 |
Scattering of Lamb Waves in a Composite Plate
Recent investigations of space construction techniques have explored the use of composite materials in the construction of space stations and platforms. These composites offer superior strength to weight ratio and are thermally stable. Examples of these materials are laminates of graphite fibers in an epoxy or a metal (Al, Mg) matrix and boron fibers in an aluminum matrix. The overall effective elastic constants of such a medium can be calculated from fiber and matrix properties by using an effective modulus theory as shown in and . The investigation of propagation and scattering of elastic waves in composite materials is necessary in order to develop an ability to characterize cracks and predict the reliability of composite structures. The objective of this investigation is the characterization of a surface breaking crack by ultrasonic techniques. In particular, the use of Lamb waves for this purpose is studied here. The Lamb waves travel through the plate, encountering a crack, and scatter. Of interest is the modeling of the scattered wave in terms of the Lamb wave modes. The direct problem of propagation and scattering of Lamb waves by a surface breaking crack has been analyzed. This would permit an experimentalist to characterize the crack by comparing the measured response to the analytical model. The plate is assumed to be infinite in the x and y directions with a constant thickness in the z direction. The top and bottom surfaces are traction free. Solving the governing wave equations and using the stress-free boundary conditions results in the dispersion equation. This equation yields the guided modes in the homogeneous plate. The theoretical model is a hybrid method that combines analytical and finite elements techniques to describe the scattered displacements. A finite region containing the defects is discretized by finite elements. Outside the local region, the far field solution is expressed as a Fourier summation of the guided modes obtained from the dispersion equation. Continuity of tractions and displacements at the boundaries of the two regions provides the necessary equations to determine the expansion coefficients and the nodal displacements. This method was used for out-of-plane (SH) wave scattering in an isotropic plate. A combined analytical and finite element formulation for a single layered isotropic plate in the state of plane strain was investigated in . In this study the authors considered only the lowest symmetric mode and geometrically symmetric cracks. In a variational approach was used to investigate scattering by a symmetric pair of surface breaking thin slots. Employing standard elastostatic crack solutions as trial functions the authors examined the scattering by the first symmetric mode. A finite difference method was used in to calculate the scattering of Lamb and shear waves from surface breaking cracks. In a modified Wiener-Hopf technique was used to analyze scattering of Lamb waves by a crack. Applying this technique, the authors in studied quantitative sizing of spot welds in joined sheets. Besides the finite difference and finite element techniques, the analytical approaches are not suitable for analyzing arbitrarily shaped defects and anistropic media. In the hybrid method used here these defects can be of arbitrary shapes as well as inclusions of different material. Recently, using the hybrid method, the scattering by surface-breaking cracks in isotropic homogeneous and welded plates has been examined in .
KeywordsSpot Weld Crack Depth Lamb Wave Scattered Field Time Trace
Unable to display preview. Download preview PDF.
- 3.Z. Abduljabbar, S. K. Datta, and A. H. Shah, J. Appl. Phys. 20, 461 (1984).Google Scholar
- 5.B. A. Auld, and M. Tan, 1977 Ultrasonics Symposium Proceedings, p. 61 (1977).Google Scholar
- 8.F. Bendec, M. Peretz, and S. I. Rokhlin, Ultrasonics, March, 78 (1984).Google Scholar
- 9.Y. Al-Nassar, Ph.D. dissertation, University of Colorado, 1990 (unpublished).Google Scholar
- 11.R. L. Bratton, S. K. Datta, and A. H. Shah, University of Colorado, Center for Space Construction, Report No. 90-1.Google Scholar | <urn:uuid:495be44c-55ed-4ef6-bfbb-7a3473cc5e2f> | 2.8125 | 867 | Truncated | Science & Tech. | 40.447487 | 95,503,352 |
Now a research team led by the University of Illinois has identified an odorant receptor that allows male drones to find a queen in flight. The receptor, on the male antennae, can detect an available queen up to 60 meters away.
This is the first time an odorant receptor has been linked to a specific pheromone in honey bees. The findings appear in the Proceedings of the National Academy of Sciences.
The “queen substance,” or “queen retinue pheromone,” was first identified decades ago, but scientists have only recently begun to understand its structure and role in the hive. The pheromone is a primary source of the queen’s authority. It is made up of eight components, one of which, 9-oxo-2-decenoic acid (9-ODA), attracts the drones during mating flights. It also draws workers to the queen and retards their reproductive growth.
Principal investigator Hugh Robertson, a professor of entomology, said the research team pursued the receptor for the queen retinue pheromone because it was the “lowest hanging fruit” of the known honey bee odorant receptors. Robertson was among the research group that last year published the entire honey bee genome, a feat that allowed his lab to identify 170 odorant receptors in honey bees.
Robertson and his colleagues knew that male drones probably had little use for most of these receptors. The drones don’t forage and so do not need to detect the subtle scents of flowers. Their social role within the hive is virtually non-existent. They have only one task: to find and mate with a queen. Once they have accomplished this, they die.
Using a functional genomics approach, entomology postdoctoral researcher Kevin Wanner was able to determine which odorant receptors were more dominant in males than females. He found four receptors that were expressed in much higher quantities in males than females.
“These proteins are expressed in the membranes of the olfactory neurons way up in the tips of these little sensilla in the antennae of these males,” Robertson said. “A neuron goes all the way from there to the brain. Now the brain gets a signal that says, ‘I’ve smelled this chemical.’ If the chemical is 9-ODA, for the drone that means one thing and one thing only: ‘There’s a queen somewhere! Go get her!’ ”
Determining which of the four primary receptors in males was actually responding to 9-ODA was a formidable challenge.
“That’s where we were very, very lucky,” Robertson said.
By chance, at a conference on the science of olfaction, Wanner met Charles Luetje, a neuroscientist at the University of Miami who had expertise with precisely this type of problem. Luetje had perfected a technique for expressing mammalian odor-sensing receptors on the outer membranes of frog oocytes (eggs) and testing them to see which compounds activated them. When he heard of Wanner’s work in honey bees, Luetje offered to use this technique to test the four primary odor receptors of honey bee drones.
After refining and testing the technique in insects, Luetje’s graduate student Andrew Nichols exposed each of the drone odorant receptors to 9-ODA. Only one of the four receptors responded. When it bound 9-ODA, the protein receptor’s conformation changed, setting off a measurable shift in the membrane potential.
None of the four primary male odorant receptors responded to the other components of the queen pheromone. Only the 9-ODA elicited a response in one of the four, said Robertson, a discovery he called, “thrilling.”
“We grabbed the lowest hanging fruit and we got it,” Robertson said. “Of course, ultimately, we’ve got another 169 receptors to go.”
Scientists have spent decades exploring the mysteries of insect smell, but the newest tools make such research much more promising, Robertson said.
“Like so many biologists, we are wonderfully caught up in the genomic revolution,” he said. “We can sequence genomes. We can use functional genomics to narrow it down. We’ve got these assays, such as the frog oocyte, and other assays. And the genomic revolution has opened up this black box of the molecular biology of insect smell. Finally now we can peer inside.”
To view or subscribe to the RSS feed for Science News at Illinois, please go to: http://webtools.uiuc.edu/rssManager/608/rss.xml.
Editor’s note: To reach Hugh Robertson, call 217-333-0489; e-mail: firstname.lastname@example.org.
Diana Yates | University of Illinois
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 | Earth Sciences
19.07.2018 | Power and Electrical Engineering
19.07.2018 | Materials Sciences | <urn:uuid:9cfc32cf-2d4b-41cb-8b2b-8c212d940be1> | 3.46875 | 1,678 | Content Listing | Science & Tech. | 45.371754 | 95,503,372 |
ISS006-E-08778 (14 December 2002) --- View of a bubble formed as a result of a Zeolite Crystal Growth (ZCG) experiment in the Destiny laboratory on the International Space Station (ISS). Expedition Six Commander Kenneth D. Bowersox used a Space Station drill to mix 12 Zeolite samples in clear tubes. Scientists on the ground watching on TV noticed bubbles in the samples. Bowersox used a modified mixing procedure to process autoclaves to isolate bubbles. He re-inserted the samples in the ZCG furnace in Express Rack 2 in the U.S. laboratory/Destiny. This experiment has shown that the bubbles could cause larger number of smaller deformed crystals to grow. Bowersox rotated the samples so that the heavier fluid was thrown to the outside while the lighter bubbles stayed on the inside. | <urn:uuid:5654193d-83d4-4c86-a1dd-b0451e9e220f> | 3.078125 | 171 | Truncated | Science & Tech. | 53.077909 | 95,503,413 |
Changing human activities coupled with a dynamic environment over the past few centuries have caused fluctuating periods of decline and recovery of corals reefs in the Hawaiian Islands, according to a study sponsored in part by the Institute for Ocean Conservation Science at Stony Brook University.
Using the reefs and island societies as a model social-ecological system, a team of scientists reconstructed 700 years of human-environment interactions in two different regions of the Hawaiian archipelago to identify the key factors that contributed to degradation or recovery of coral reefs.
“Historical reconstruction reveals recovery in Hawaiian coral reefs,” which was published online today in the journal PLoS ONE, concludes that historical changes in human societies and their relationships with coral reef ecosystems can explain whether these ecosystems exhibit patterns of sustainability and resilience or decline and degradation. Dr. John N. Kittinger, lead author of the study, was a National Science Foundation Graduate Fellow in the Department of Geography at the University of Hawai‘i at Mânoa when the reconstruction was conducted. He is now an Early Career Social Science Fellow at Stanford University’s Center for Ocean Solutions.
“Our reconstructed ecological changes included an intensive review and assessment of archaeological deposits, historical observations of ecosystem conditions, and modern ecological and fishery data,” said Dr. Kittinger. “Using these data sets, our findings demonstrate that we can’t always view environmental degradation solely through the lens of simplistic cause-consequence relationships. In the historical recovery periods we uncovered, we found that human agency is partly responsible for environmental recovery, which shows that not all human-environment interactions lead to irreversible deleterious outcomes and that degraded ecosystems may still retain the adaptive capacity and resilience to recover from human impacts.”
“This reconstruction shows that human-environment interactions need to be included when considering the factors that contribute to the degradation of an ecosystem,” said Dr. Ellen Pikitch, executive director of the Institute for Ocean Science and Professor at Stony Brook University. “Understanding past interactions can be crucial in determining best practices for present-day management of coral reef ecosystems.”
The analysis suggests that in the Main Hawaiian Islands marine exploitation was highest in the early period after Polynesian settlement more than 700 years ago. By 1400, however, reef-derived protein sources became less important than those derived from domesticated animals, and a suite of coral reef resource conservation strategies was implemented by Native Hawaiian societies, allowing reefs to recover. This recovery continued as traditional reef-fishing subsistence practices were abandoned through the post-European contact period after 1778 due to the introduction of epidemic diseases to the Native Hawaiian population. By the early to mid-1800s, however, reefs again went into decline due to overexploitation, land-based pollution, and other factors associated with changes in demography, economic systems, and new technologies. The analysis shows that negative impacts continued and intensified to the present day, exhibiting only a brief reprieve in the 1940s due to the closure of nearshore marine areas during World War II.
“Reefs in the Main Hawaiian Islands have been declining for more than 150 years, and similar degradation that has occurred in other reef ecosystems indicates that we may be approaching a tipping point or threshold, beyond which recovery is doubtful,” said Dr. Kittinger. “If we look at historical ecosystem recoveries, reversing this decline will require protection of a broad range of habitat types over large areas, such as marine no-take reserves. Additionally, appropriate institutions and policies will need to be in place to effectively engage the diverse community of ocean-users in Hawai‘i in collaborative marine ecosystem stewardship.”
Unlike the Main Hawaiian Islands, researchers found that coral reefs in the Northwestern Hawaiian Islands (NWHI) have long functioned as a geographic refuge due to their isolation and limited human population. They also benefited from cultural protection as a sacred ancestral homeland in Native Hawaiian society. The analysis shows that they did, however, suffer from some of the same negative impacts of the post-European contact period as coral reefs in the Main Hawaiian Islands. After World War II, however, reefs in this region began to recover from historical impacts due to human depopulation in the area, conservation efforts, and decreases in commercial activities involving the reefs. NWHI reefs are now among the most diverse and abundant coral reef ecosystems in the world, and provide an example of how healthy reefs that have recovered from human impacts can look.
“The substantial resilience and adaptive capacity of coral reefs demonstrated in this study provide reason for hope and suggest that we should not dismiss the possibility of bringing even the most degraded reefs back to health,” said Dr. Pikitch.
This research was supported by the Institute for Ocean Conservation Science, National Science Foundation, the Australian Research Council’s Centre of Excellence for Coral Reef Studies, and the Marine Conservation Biology Institute’s 2008 Mia J. Tegner Memorial Research Grant in Marine Environmental History and Historical Marine Ecology.
Editor’s Note: For more information on “Historical reconstruction reveals recovery in Hawaiian coral reefs,” please visit http://dx.plos.org/10.1371/journal.pone.0025460.
Photos of healthy and degraded reefs in the Hawaiian Islands are available by request.
The Center for Ocean Solutions (COS) works to solve the major problems facing the ocean, and prepares both current and future leaders to take on these challenges. It is a collaboration among Stanford University (through Stanford’s Woods Institute for the Environment, http://woods.stanford.edu/ and Hopkins Marine Station, http://www-marine.stanford.edu), the Monterey Bay Aquarium, http://www.montereybayaquarium.org/ and the Monterey Bay Aquarium Research Institute (MBARI), http://www.mbari.org/.
The Institute for Ocean Conservation Science at Stony Brook University is dedicated to advancing ocean conservation through science. The Institute transforms real-world policy while pursuing serious science, both of which are essential for ocean health. For more information, go to www.oceanconservationscience.org.
The University of Hawai`i at Mânoa serves approximately 20,000 students pursuing more than 225 different degrees. Coming from every Hawaiian island, every state in the nation, and more than 100 countries, UH Mânoa students thrive in an enriching environment for the global exchange of ideas. For more information, visit http://manoa.hawaii.edu. Follow us on Facebook http://www.facebook.com/uhmanoa and Twitter http://twitter.com/UHManoaNews.
Upcycling of PET Bottles: New Ideas for Resource Cycles in Germany
25.06.2018 | Fraunhofer-Institut für Betriebsfestigkeit und Systemzuverlässigkeit LBF
Dry landscapes can increase disease transmission
20.06.2018 | Forschungsverbund Berlin e.V.
A new manufacturing technique uses a process similar to newspaper printing to form smoother and more flexible metals for making ultrafast electronic devices.
The low-cost process, developed by Purdue University researchers, combines tools already used in industry for manufacturing metals on a large scale, but uses...
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
20.07.2018 | Power and Electrical Engineering
20.07.2018 | Information Technology
20.07.2018 | Materials Sciences | <urn:uuid:4c06fdf9-4970-4d9b-8f68-9ed8a00aefc7> | 3.375 | 1,970 | Content Listing | Science & Tech. | 29.554514 | 95,503,418 |
Discovery of a new type of chaos by physicists from Chemnitz draws worldwide attention – opportunities in communication, cryptography, and computing
For 40 years, it has been known that lasers utilizing time-delayed feedback of the original signal can cause chaotic intensity fluctuations (top of figure, second image). However, for many potential applications, this type of chaos is too sensitive to perturbations.
The discovery made by the theoretical physicists David Müller, Dr. Andreas Otto, and Prof. Günter Radons from Chemnitz University of Technology could change this situation. They found that a small modification of such experiments – a periodic modulation of the delay – can lead to totally different, novel intensity variations, which are characterized by sequences of plateaus (bottom of figure, second image).
Special features of this type of signal, which is now called laminar chaos, are on one hand the robustness of the location and the form of the plateaus against perturbations, and on the other hand that the heights vary chaotically from plateau to plateau, and thus can serve as a carrier of information.
This high robustness of the information content against perturbations makes this newly discovered form of chaos interesting for modern information technologies such as fast optical realizations of chaos communication, chaos cryptography, or reservoir computing.
The fundamental importance of the research results obtained by the theoretical physicists has made it possible to already publish two articles about their work in the most internationally renowned journal, ‘Physical Review Letters’.
Over the last years, Prof. Günter Radons’s group has achieved such a reputation in the field that it was possible to assemble the worldwide leading experts in delay systems during the upcoming 675. WE-Heraeus Seminar: Delayed Complex Systems 2018, which will take place in the Bad Honnef Physikzentrum from July 2 - 5 (Scientific organization: A. Otto, G. Radons, Chemnitz University of Technology, and Wolfram Just, Queen Mary University of London).
Background knowledge: Chaos & Delay
In physics, the term ‘chaos’ characterizes a type of motion which appears very irregular but at the same time follows definite laws. Almost all systems show this feature, which makes it impossible to make long-term predictions. Well-known examples from everyday life are the weather or the drawing of lottery numbers. Laser light or the size of bacterial colonies can also vary chaotically. ‘Delay’ is a special term which characterizes the time between cause and effect. In many cases, it cannot be ignored and can bring about extremely complicated patterns of movement.
Background knowledge: Wilhelm and Else Heraeus Seminar
The organization of scientific seminars is the oldest and best known funding activity of the Wilhelm and Else Heraeus Foundation. The program has brought together more than 30,000 participants since its establishment in 1975, more than one third from foreign countries. The topics of the seminars cover all fields of modern physics including areas of intersection with other disciplines. WE-Heraeus Seminars encompass the current frontiers of science and are internationally oriented. WE-Heraeus Seminars are applied for by one or several scientists according to the rules of the foundation. After evaluation and recommendation by the scientific advisory committee, the foundation council can grant an approval. The seminars are run by the foundation in close cooperation with the applicant(s) (i.e. the scientific organizers).
The Chemnitz physicists’ articles in ‘Physical Review Letters’:
D. Müller, A. Otto and G. Radons: Laminar Chaos, Phys. Rev. Lett. 120, 084102 (2018).
A. Otto, D. Müller and G. Radons: Universal Dichotomy for Dynamical Systems with Variable Delay, Phys. Rev. Lett. 118, 044104 (2017).
Further information can be obtained from Prof. Günter Radons, Chair of Complex Systems and Nonlinear Dynamics, Institute of Physics, Telefon 0371 531-21870, E-Mail firstname.lastname@example.org.
Matthias Fejes | Technische Universität Chemnitz
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
20.07.2018 | Materials Sciences | <urn:uuid:a176ac1d-e3f3-4d6c-ab2c-d74cfbb9ec7e> | 3.234375 | 1,449 | Content Listing | Science & Tech. | 37.331632 | 95,503,419 |
Washington: Researchers in the US have discovered "beautifully preserved" 15 million-year-old thin protein sheets in fossilised shells of a snail-like, shallow marine-dwelling mollusc called Ecphora.
The now extinct Ecphora species lived in the mid-Miocene era - between eight and 18 million years ago.
"We were amazed to find that the shells, once dissolved in dilute acid, released intact thin sheets of shell proteins more than a centimeter across," said main author John Nance and his colleagues from Carnegie Institution for Science in Washington.
Chemical analysis including spectroscopy and electron microscopy of these sheets revealed that they are indeed shell proteins that were preserved for up to 15 million years.
"These are some of the oldest and best-preserved examples of a protein ever observed in a fossil shell," one of the authors Robert Hazen said.
Remarkably, the proteins share characteristics with modern mollusc shell proteins. They both produce thin, flexible sheets of residue that is the same colour as the original shell after being dissolved in acid.
Ecphora is known for an unusual reddish-brown shell colour, making it one of the most distinctive North American molluscs of its era.
The study appeared in the journal Geochemical Perspectives Letters. | <urn:uuid:22a8966f-ca04-4c06-9f49-06a0096f8c38> | 3.828125 | 272 | News Article | Science & Tech. | 32.244559 | 95,503,436 |
Life forms: Schopf thinks these marks are fossils of ancient bacteria.
Dishing the dirt: Brasiers team reckons geological processes made the squiggles.
Gloves are coming off in ancient bacteria bust-up.
A claim to have found evidence of the oldest living things on Earth is being fiercely contested. The argument looks set to run and run, and no one may win, but it may lead to a better understanding of the origins of life on our planet.
The debate is academic, but its implications are not. The ’fossil bacteria’ in question are around 3.5 billion years old. That’s roughly one billion years older than the only confirmed fossil bacteria.
Schopf’s team studied the structure and chemical composition of the squiggles with a technique called laser-Raman imagery. The group argues that the marks are made up of carbon molecules, which are the decay products of living bacterial cells. "They are tiny little fossils," says Schopf.
Brasier’s team repeated some of Schopf’s analyses recently and disagrees. "Schopf’s hypothesis is deeply flawed," Brasier says.
Brasier’s team agrees that the marks’ chemical composition appears biological in origin. But the group thinks that they actually arose through unusual geological processes around ancient hydrothermal vents, where hot volcanic gases rise to the surface.
What’s more, the group says, the squiggles look nothing like other ancient microbes. "The shapes are far too complicated to be bacteria," says Brasier, who feels Schopf should drop his claim.
Brasier’s group asserts that biological-seeming molecules can result from reactions between the carbon dioxide and monoxide released by hot, metal-rich hydrothermal vents. These molecules could then have been sculpted into bacteria-esque filaments as the hot rocks they were born in cooled.
If this was the case, argues Schopf, such material would be found everywhere. So far it hasn’t been. "The facts are going to win and I’ve got the data," he says.
The one thing both parties agree on is that only time will tell. Schopf is continuing to analyse his putative fossils. A nanoscale examination of their ’cell membranes’ will, he claims, prove beyond doubt that the Apex chert does contain the oldest known remains of life on Earth.
Brasier and his team are now investigating the kind of chemical reactions that they believe produced the squiggles. The researchers suspect the reactions could themselves have created complex molecules such as amino acids and be the source of life on Earth. "Schopf may have stumbled on a site that may explain how life got started," says Brasier.
TOM CLARKE | © Nature News Service
Colorectal cancer risk factors decrypted
13.07.2018 | Max-Planck-Institut für Stoffwechselforschung
Algae Have Land Genes
13.07.2018 | Julius-Maximilians-Universität Würzburg
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
13.07.2018 | Event News
13.07.2018 | Materials Sciences
13.07.2018 | Life Sciences | <urn:uuid:3b5183a8-21d5-45ca-9fd6-e38e51572412> | 3.375 | 1,238 | Content Listing | Science & Tech. | 46.815541 | 95,503,442 |
Measurements taken at the molecular scale have for the first time confirmed a key property that could improve our knowledge of how the heart and lungs function.
University of Washington researchers have shown that a favorable electrical property is present in a type of protein found in organs that repeatedly stretch and retract, such as the lungs, heart and arteries. These findings are the first that clearly track this phenomenon, called ferroelectricity, occurring at the molecular level in biological tissues.
The researchers published their findings online June 23 in the Proceedings of the National Academy of Sciences.
“We wanted to bring in different experimental techniques, evidence and theoretical understanding of ferroelectricity in biological functions,” said Jiangyu Li, a UW professor of mechanical engineering and corresponding author of the paper. “We certainly have much more confidence now in the phenomenon itself.”
Ferroelectricity is a response to an electric field in which a molecule switches from having a positive to a negative charge. This switching process in synthetic materials serves as a way to power computer memory chips, display screens and sensors. This property only recently has been discovered in animal tissues and researchers think it may help build and support healthy connective tissues in mammals.
A research team led by Li first discovered ferroelectric properties in biological tissues in 2012, then in 2013 found that glucose can suppress this property in the body’s connective tissues, wherever the protein elastin is present. But while ferroelectricity is a proven entity in synthetic materials and has long been thought to be important in biological functions, its actual existence in biology hasn’t been firmly established.
This study proves that ferroelectric switching happens in the biological protein elastin. When the researchers looked at the base structures within the protein, they saw similar behavior to the unit cells of solid-state materials, where ferroelectricity is well understood.
“When we looked at the smallest structural unit of the biological tissue and how it was organized into a larger protein fiber, we then were able to see similarities to the classic ferroelectric model found in solids,” Li said.
The researchers wanted to establish a more concrete, precise way of verifying ferroelectricity in biological tissues. They used small samples of elastin taken from a pig’s aorta and poled the tissues using an electric field at high temperatures. They then measured the current with the poling field removed and found that the current switched direction when the poling electric field was switched, a sign of ferroelectricity.
They did the same thing at room temperature using a laser as the heat source, and the current also switched directions.
Then, the researchers tested for this behavior on the smallest-possible unit of elastin, called tropoelastin, and again observed the phenomenon. They concluded that this switching property is “intrinsic” to the molecular make-up of elastin.
The next step is to understand the biological and physiological significance of this property, Li said. One hypothesis is that if ferroelectricity helps elastin stay flexible and functional in the body, a lack of it could directly affect the hardening of arteries.
“We may be able to use this as a very sensitive technique to detect the initiation of the hardening process at a very early stage when no other imaging technique will be able to see it,” Li said.
The team also is looking at whether this property plays a role in normal biological functions, perhaps in regulating the growth of tissue.
Co-authors are Pradeep Sharma at the University of Houston, Yanhang Zhang at Boston University, and collaborators at Nanjing University and the Chinese Academy of Sciences.
The research was funded by the National Science Foundation, National Institutes of Health, the National Natural Science Foundation of China and the UW.
For more information, contact Li at firstname.lastname@example.org or 206-543-6226.
Michelle Ma | Eurek Alert!
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:ccfb2da1-d941-4a04-bc3b-0ca1ee43f768> | 3.3125 | 1,454 | Content Listing | Science & Tech. | 35.429046 | 95,503,486 |
Physics of Molecular Clouds from Millimeter Wave Line Observations
The advent of millimeter wave molecular line astronomy has made it possible over the past seven years for astronomers to study the physics and chemistry of dense interstellar clouds. The dominant gaseous constituent of these clouds is molecular hydrogen, H2, and hence the name molecular clouds. In fact all interstellar clouds with hydrogen density greater than 100 cm-3 are composed primarily of molecular and not atomic hydrogen. The dominance of molecules in dense clouds is due to the self shielding of H2 from the photodissociating starlight at the wavelengths of the ultraviolet Lyman bands. At a density of 100 cm-3 the production rate of H2 on grain surfaces is sufficient to build up a layer which is optically thick to the photodissociation occurring in the lines of the Lyman band. Inside the clouds, the photodissociation, which is limited to the line wings, is reduced by several orders of magnitude and the production rate dominates with almost all hydrogen converted to H2. Since H2 does not have a true continuum photodissociation at λ > 912 Å, the self shielding of the bound-bound-free process of the Lyman bands is critical to the distinction between atomic and molecular clouds.
KeywordsOptical Depth Molecular Cloud Column Density Black Body Radiation Virial Theorem
Unable to display preview. Download preview PDF. | <urn:uuid:aefca24d-7eb3-4772-813f-e0c8c882620f> | 3.484375 | 288 | Truncated | Science & Tech. | 31.238373 | 95,503,509 |
Understanding Colonial Traits Using Symbiosis Research and Ecosystem Ecology
- 48 Downloads
E. O. Wilson (1974: 54) describes the problem that social organisms pose: “On what bases do we distinguish the extremely modified members of an invertebrate colony from the organs of a metazoan animal?” This framing of the issue has inspired many to look more closely at how groups of organisms form and behave as emergent individuals. The possible existence of “superorganisms” test our best intuitions about what can count and act as genuine biological individuals and how we should study them. As we will discuss, colonies of certain organisms display many of the properties that we usually reserve only to individual organisms. Although there is good reason to believe that many social insects form genuine emergent biological individuals, the conclusion offered here is of a slightly different sort. I will argue that to understand some social insects’ interactions and the emergent traits they give rise to, it may be helpful to shift our understanding from a community-level approach to an ecosystem-level approach. I will argue that viewing certain insect colonies (termites) as parts of ecosystems allows us to better understand some of the adaptations that have emerged from their evolution.
Keywordsadaptation biological individuality colony ecology emergence social insects
Unable to display preview. Download preview PDF.
- Ahmadjian V, Jacobs J (1983) Algal-fungal relationships in lichens: Recognition, synthesis, and development. In: Symbiosis (Goff LJ, ed), 147–172. Cambridge: Cambridge University Press.Google Scholar
- Bouchard F (2004) Evolution, Fitness and the Struggle for Persistence. PhD thesis, Duke University, Durham, NC.Google Scholar
- Bouchard F (in press) How ecosystem evolution strengthens the case for functional pluralism. In: Functions: Selection and Mechanism (Huneman P, ed), Springer.Google Scholar
- Brandon RN (1990) Adaptation and Environment. Princeton, NJ: Princeton University Press.Google Scholar
- Hamilton A, Smith N, Haber M (2009) Social insects and the individuality thesis: Cohesion and the colony as a selectable individual. In: Organization of Insect Societies: From Genome to Sociocomplexity (Gadau J, Fewell J, ed), 572–589. Cambridge, MA: Harvard University Press.Google Scholar
- Hölldobler B, Wilson EO (2008) The Superorganism: The Beauty, Elegance, and Strangeness of Insect Societies. New York: Norton.Google Scholar
- McShea DW, Venit E (2000) What is a part? In: The Character Concept in Evolutionary Biology (Wagner GP, ed), 259–284. San Diego, CA: Academic Press.Google Scholar
- Paracer S, Ahmadjian V (2000) Symbiosis: An Introduction to Biological Associations. Oxford: Oxford University Press.Google Scholar
- Rosenberg A, Bouchard F (2009) Fitness. In: The Stanford Encyclopedia of Philosophy (Summer 2009 Edition), (Zalta EN, ed), URL: http://plato.stanford.edu/archives/sum2009/entries/fitness.
- Sapp J (1994) Evolution by Association: A History of Symbiosis. Oxford: Oxford University Press.Google Scholar
- Sober E (2001) The two faces of fitness. In: Thinking About Evolution: Historical, Philosophical, and Political Perspectives (Singh RS, Costas B, Paul DB, Beatty J, eds), 309–321. Cambridge: Cambridge University Press.Google Scholar
- Thoday JM (1953) Components of fitness. Symposia of the Society for Experimental Biology 7: 96–113.Google Scholar
- Turner JS (2000) The Extended Organism: The Physiology of Animal-built Structures. Cambridge, MA: Harvard University Press.Google Scholar
- Wilson EO (1971) The Insect Societies. Cambridge, MA: Harvard University Press.Google Scholar
- Wilson J (2007) Biological Individuality: The Identity and Persistence of Living Entities. Cambridge: Cambridge University Press.Google Scholar
- Wilson RA (2007) The biological notion of individual. In: The Stanford Encyclopedia of Philosophy (Fall 2008 Edition), (Zalta EN, ed), URL: http://plato.stanford.edu/archives/fall2008/entries/biology-individual. | <urn:uuid:986f9fe9-cf7d-4443-8057-a76031b69e83> | 2.71875 | 934 | Academic Writing | Science & Tech. | 35.138625 | 95,503,522 |
What Is the Theory of Plate Tectonics
Edited by TPappin, Sharingknowledge, Jen Moreau
What is Plate Tectonics?
Plate tectonics is a theory that was first proposed in the early 1900s by scientist Alfred Wegener, but was not said to be true until the 1960s.
- 1It states that Earth's outer shell is made up of many different plates, all which glide over top the Earth's mantle. The plates are found in the lithosphere. Also known as continental drift, the theory of plate tectonics is the reasoning behind why and how continents are constantly moving.What It States.Advertisement
- 2The movement of continents is caused by what's happening beneath Earth's crust. Seismic waves, which are waves of energy that occur when tectonic plates push against each other and pull apart, cause rock within the Earth to suddenly break, causing disruption and in some cases, even explosion or volcanoes. Seismologist Nicolas Van der Elst describes the process as "…a pot boiling on a stove."Why It Occurs.
The History of Plate Tectonics
When Alfred Wegener first proposed the theory of continental drift, he described the tectonic plates, or the continents, as puzzle pieces fitting together. He continued to explain his theory after realizing the Earth's surface changing significantly over time while noticing that continents which, at one point, were not separated, were. This was also noted by paleontologists when fossils of the same species were found on different continents, now separated. Their combined observations determined that the Earth's lithosphere had, in fact, been moving over time.
- 1Not everyone agreed with Wegener's theory, as there wasn't really a way to prove why the continents were moving, other than his observation. Many other scientists believed it was due to the Earth's temperatures, causing continents to contract.Controversy.
- 2Wegener originally proposed that Earth's continents pushed against the ocean floors, although he was unable to identify the direct cause of continental drift. For that reason, geologists deemed his theory false; however, it did lay the groundwork for the development of plate tectonics and over time, additional evidence was gathered.Disproved.
- 4In the 1960s is when the plate tectonic theory started to gain acceptance across the world.1960s.
The tectonic plates are found in the Earth's lithosphere, which is the outermost shell, or in other words, the crust and the mantle combined. The lithosphere is broken up into seven or eight major tectonic plates, as well as several minor ones.
- 1Each of the major tectonic plates has their own unique name: African plate, Antarctic plate, Eurasian plate, Indo-Australian plate, North American plate, Pacific plate and South American plate. These plates account for 94% of the Earth's surface.Their Names.
- 2The tectonic plates are constantly in motion, which is what ultimately starts earthquakes, volcanoes, mountain formations and oceanic trenches. Each plate is about 80 km deep and moves only a few inches each year.What They Do.
- 1Plate boundaries are where each of the tectonic plates meet. There are three main types of plate boundaries, also known as subduction zones or convergent margins: convergent boundaries, divergent boundaries and transform boundaries.What They Are.
- 2When two plates meet underwater and one or both are composed of oceanic crust. The plate which is denser is pushed underneath the less dense tectonic plate, which eventually melts and is destroyed completely.Convergent Boundaries.
- 3Divergent boundaries are when two tectonic plates are moving away from one another. This process can occur underwater or on land.Divergent Boundaries.
- 4Transform boundaries are when two tectonic plates slide horizontally past one another. Like divergent boundaries, transform boundaries can occur underwater or on land. When the two plates slide past each other, friction is caused, building up stress in both plates, which then causes an earthquake. This is also known as a fault, or a fault plane.Transform Boundaries.
- 1Plate collisions occur when the subduction zone between two plates is destroyed. It is a phenomenon of the plate tectonics. When this happens, mountains can be formed, volcanoes can erupt and two continents ultimately come together, affecting what the map of the Earth looks like.What Is It?
- 2The Himalayan Mountain formed as a result of the Indian Plate and Eurasian Plate colliding. This process began 50 million years ago and continues to this day. The continental crust of both plates buckled, causing rock to pile up.The Himalayas.
- 4All subduction zones must eventually disappear. Once they do, the tectonic plates will collide, creating a mountain range. This has already occurred a number of times across the world.Subduction Zones.
- 5The Wilson Cycle refers to the recurrent opening and closing of ocean basins, causing the Earth to move. It starts when magma erupts toward the Earth's crust, forming an ocean basis, acting as a final resting spot for the settled magma.The Wilson Cycle.
Referencing this Article
If you need to reference this article in your work, you can copy-paste the following depending on your required format:
APA (American Psychological Association)
What Is the Theory of Plate Tectonics. (2017). In ScienceAid. Retrieved Jul 22, 2018, from https://scienceaid.net/What_Is_the_Theory_of_Plate_Tectonics
MLA (Modern Language Association) "What Is the Theory of Plate Tectonics." ScienceAid, scienceaid.net/What_Is_the_Theory_of_Plate_Tectonics Accessed 22 Jul 2018.
Chicago / Turabian ScienceAid.net. "What Is the Theory of Plate Tectonics." Accessed Jul 22, 2018. https://scienceaid.net/What_Is_the_Theory_of_Plate_Tectonics.
Categories : Geology
Recent edits by: Sharingknowledge, TPappin | <urn:uuid:812525f6-bdf3-4164-8617-e27e89747bb4> | 4.09375 | 1,292 | Knowledge Article | Science & Tech. | 44.275911 | 95,503,523 |
Artificial muscles and self-propelled goo may be the stuff of Hollywood fiction, but for UC Santa Barbara scientists Omar Saleh and Deborah Fygenson, the reality of it is not that far away. By blending their areas of expertise, the pair have created a dynamic gel made of DNA that mechanically responds to stimuli in much the same way that cells do. The results of their research were published online in the Proceedings of the National Academy of Sciences.
“This is a whole new kind of responsive gel, or what some might call a ‘smart’ material,” said Saleh, associate professor of materials, affiliated with UCSB’s Biomolecular Science and Engineering program. “The gel has active mechanical capabilities in that it generates forces independently, leading to changes in elasticity or shape, when fed ATP molecules for energy – much like a living cell.”
Their DNA gel, at only 10 microns in width, is roughly the size of a eukaryotic cell, the type of cell of which humans are made. The miniscule gel contains within it stiff DNA nanotubes linked together by longer, flexible DNA strands that serve as the substrate for molecular motors.
“DNA gives you a lot more design control,” said Fygenson, associate professor of physics and also affiliated with UCSB’s BMSE program. “This system is exciting because we can build nano-scale filaments to specifications.” Using DNA design, she said, they can control the stiffness of the nanotubes and the manner and extent of their cross-linking, which will determine how the gel responds to stimuli.
Using a bacterial motor protein called FtsK50C, the scientists can cause the gel to react in the same way cytoskeletons react to the motor protein myosin – by contracting and stiffening. The protein binds to predetermined surfaces on the long linking filaments, and reels them in, shortening them and bringing the stiffer nanotubes closer together. To determine the gel’s movement the scientists attached a tiny bead to its surface and measured its position before and after activation with the motor protein.
The breakthrough, said Saleh, is that this gel “quantitatively shows similar active fluctuations and mechanics to cells.”
“This new material could provide a means for controllably testing active gel mechanics in a way that will tell us more about how the cytoskeleton works,” Saleh said. Like a cell, which consumes adenosine triphosphate (ATP) for energy, the DNA gel’s movement runs on ATP, allowing for faster, stronger mechanics than other smart gels based on synthetic polymers.
“The development of active gels represents a water-shed event for the broader materials community,” commented Craig Hawker, director of the Materials Research Laboratory at UCSB: an NSF MRSEC, which provided seed money for their research. “By exploiting cellular building blocks, it offers unique design parameters when compared to existing gel systems that can be used in a wide range of both established biomedical applications as well as totally new applications.”
The project has potential applications for a variety of fields, including smart materials, artificial muscle, understanding cytoskeletal mechanics and research into nonequilibrium physics, as well as DNA nanotechnology. Long-term implications of this research are significant, Hawker added, with the final result being “a fundamental breakthrough in soft-materials science and engineering.”
Having created a gel that can replicate contractions, Saleh and Fygenson are now looking to refine their technique and enable distinct movements, such as twisting and crawling, or using other motor proteins that would allow the gel to mimic other cell behaviors, such as shape-shifting and dividing.
“Biology provides a wide range of motors that we have only begun to explore,” Saleh said.
“And the suite of nanostructure designs and geometries at our disposal is nearly limitless,” echoed Fygenson.
University of California – Santa Barbara | <urn:uuid:b3c0a1cc-b023-409b-8018-eb7511ebe09a> | 3.34375 | 857 | News Article | Science & Tech. | 25.963362 | 95,503,536 |
- Research highlight
- Open Access
The amazing world of bacterial structured RNAs
© BioMed Central Ltd 2010
Published: 15 March 2010
The discovery of several new structured non-coding RNAs in bacterial and archaeal genomes and metagenomes raises burning questions about their biological and biochemical functions.
See related research article by Weinberg et al.: http://genomebiology.com/2010/11/3/R31
The compact genomes of bacteria contain 10 to 15% non-coding DNA sequences, which are transcribed into non-coding RNAs. Several classes of non-coding RNAs are small, less than 80 to 150 nucleotides, and act as post-transcriptional regulators by targeting mRNAs. Another large class of non-coding RNAs act in cis by binding structured elements in the 5' untranslated regions of mRNAs. Perhaps the best known are called riboswitches; upon binding a metabolite, the fold of the transcript is modified and this influences either the termination of transcription or the initiation of translation .
Some longer non-coding RNAs have also been detected in recent years. For example, RNAIII present in several Gram-positive bacteria is 500 nucleotides long and contains structured regions framing an open-reading frame . However, two recent papers from Ron Breaker's group increase the number of large non-coding RNAs astonishingly [3, 4]. Several new smaller non-coding RNAs are also identified. Strikingly, most of the new non-coding RNAs are structurally very complex. The complexity of some of the larger ones seems similar to that of the large ribozymes, such as the self-splicing group I and group II introns. These observations show, once again, how little we know about the microbial world: a great proportion of these new non-coding RNAs were identified in metagenomes or in environmental DNA sequences.
The search for non-coding RNAs
The search for non-coding RNAs in genomes is far from trivial . Even for homologous and functionally well characterized RNA molecules, such as the ubitquitous RNaseP or the telomerase RNA, the search cannot be reliably automated because of the large and unpredictable variation in the length of the RNA transcript, with new insertions appearing in an otherwise globally similar secondary structure. On the other hand, the de novo search for the presence of non-coding RNAs within intergenic regions is plagued by false positives because of the poor discriminative power. Various computer tools have been produced for searching for potential non-coding RNAs in genomes by exploiting the thermodynamic stabilities of the helices formed [6, 7]. The tools are generally dedicated to searching for either cis-acting RNAs (such as riboswitches) or trans-acting RNAs (such as the RNAs binding by full or partial complementarity to another RNA, either non-coding or coding).
Computer tools have been around for some time for searching RNAs on the basis of a known element of secondary structure. It has also been established several years ago that secondary structure alone is not enough for predicting non-coding RNA . The computational pipeline followed by Weinberg and coworkers [3, 4] exploits the power of comparative sequence analysis and involves sophisticated automatic techniques combined with manual intervention. The central tool used by Weinberg and coworkers [3, 4] is CMfinder, which can derive RNA motifs and secondary structures from a set of unaligned RNA sequences . However, in order to appreciate what these programs attempt to do, it is worth recalling how complex the structures of non-coding RNAs can be.
What is meant with structural complexity? The first level of folding of the transcribed RNA is the fold-back hairpin capped by a loop. Such a simple single hairpin can have profound biological effects. In bacteria, insertion of selenocysteine (a version of cysteine containing selenium rather than sulfur) occurs because the stop codon to be read as a selenocysteine codon is followed by a small hairpin. Series of hairpins can form, which, upon binding a ligand (another RNA, a protein or a metabolite), will lead to a more complex fold or to cleavage of the RNA. Structural complexity starts to appear when hairpins branch off from a hairpin, forming a three-way or multi-way junction. Naturally, further branching off of hairpins can occur within an already branched off hairpin. Because hairpins in three-dimensional space form RNA helices, which are bulky, the available space they can occupy is restricted, leading to co-axial or parallel stacking of some of them and, consequently, intricate three-dimensional architectures.
Can we detect and assess structural complexity?
Such non-Watson-Crick pairs and the modules they form are an integral part of the tertiary structure; consequently, they are not predicted by the usual secondary structure programs that consider only Watson-Crick pairs. Correct secondary structure predictions should leave the bases that are potentially involved in non-Watson-Crick interactions as unpaired and single-stranded. Incorrect secondary structure predictions tend to predict that the bases that, in the native fold, would be forming non-Watson-Crick pairs are, instead, involved in secondary structure helices; this mis-prediction prevents the correct identification of structural elements key for the tertiary structure. Consequently, secondary structure predictions that allow for the possibility that single-stranded regions can form a known and recurrent RNA module have a higher probability of being functionally correct. Furthermore, given that such RNA modules are key elements of the tertiary structure, their presence indicates a potentially highly structured molecule.
Some striking cases are present in some secondary structures proposed for the newly reported RNAs. For example, the GOLLD (stands for Giant, Ornate, Lake- and Lactobacillales-Derived) RNA contains two G-bulged modules, one internal loop within a hairpin, and a second loop that forms a complex junction comprising four helices. In a very unusual example, the two strands forming the G-bulged modules exchange in the sequences (69% of the observed sequences start with 5'-AAA...AGUA-3' and 18% 5'-AGUA...AAA-3'; the remaining 5% adopt a simpler purine-rich module). Another RNA, dct-1, has a cluster of four G-bulged modules positioned around a three-way junction . Interestingly, dct-1 is observed only in Dictyoglomus thermophilum, an extreme thermophile.
RNAs in metagenomes
As discussed by Weinberg and colleagues [3, 4], several of the new RNAs could not have been discovered in the genomes of cultured bacteria known so far because such genomes do not contain the reported RNAs (except for some of the most recently sequenced genomes). Thus, the large collection of new RNAs are most probably just the tip of the iceberg, and an incredible number of still-to-be-discovered non-coding RNAs may be present in environmental sequences. The naming of the RNAs will continue to reflect the harvest of the sequences (for example, whalefall-1, Ocean-5, Soil-1 or Rhodopirellula-1).
The two recent papers [3, 4] are extremely rich in information content, with large and complete supplementary material. They present many more RNAs, some of which are new riboswitches, with several containing various structural elements, such as interactions between loops or between a loop and a single-stranded region. Here, we highlight one particular aspect of the work. In the future, much more biochemical work, tedious and time-consuming, will be necessary to characterize the functions of the non-coding RNAs, to see whether they interact with a metabolite, another RNA or a protein and participate in regulatory networks, to identify those RNAs with catalytic power and to assess how widespread they are and why they were so elusive up to now.
- Barrick JE, Breaker RR: The distributions, mechanisms, and structures of metabolite-binding riboswitches. Genome Biol. 2007, 8: R239-10.1186/gb-2007-8-11-r239.PubMedPubMed CentralView ArticleGoogle Scholar
- Benito Y, Kolb FA, Romby P, Lina G, Etienne J, Vandenesch F: Probing the structure of RNAIII, the Staphylococcus aureus agr regulatory RNA, and identification of the RNA domain involved in repression of protein A expression. RNA. 2000, 6: 668-679. 10.1017/S1355838200992550.PubMedPubMed CentralView ArticleGoogle Scholar
- Weinberg Z, Perreault J, Meyer MM, Breaker RR: Exceptional structured noncoding RNAs revealed by bacterial metagenome analysis. Nature. 2009, 462: 656-659. 10.1038/nature08586.PubMedPubMed CentralView ArticleGoogle Scholar
- Weinberg Z, Wang JX, Bogue J, Yang J, Corbino KA, Moy RH, Breaker RM: Comparative genomics reveals 104 candidate structured RNAs from bacteria, archaea and their metagenomes. Genome Biol. 2010, 11: R31-PubMedPubMed CentralView ArticleGoogle Scholar
- Menzel P, Gorodkin J, Stadler PF: The tedious task of finding homologous noncoding RNA genes. RNA. 2009, 15: 2075-2082. 10.1261/rna.1556009.PubMedPubMed CentralView ArticleGoogle Scholar
- Gorodkin J, Hofacker IL, Torarinsson E, Yao Z, Havgaard JH, Ruzzo WL: De novo prediction of structured RNAs from genomic sequences. Trends Biotechnol. 2009, 28: 9-19. 10.1016/j.tibtech.2009.09.006.PubMedView ArticleGoogle Scholar
- Yao Z, Weinberg Z, Ruzzo WL: CMfinder - -a covariance model based RNA motif finding algorithm. Bioinformatics. 2006, 22: 445-452. 10.1093/bioinformatics/btk008.PubMedView ArticleGoogle Scholar
- Rivas E, Eddy SR: Secondary structure alone is generally not statistically significant for the detection of noncoding RNAs. Bioinformatics. 2000, 16: 583-605. 10.1093/bioinformatics/16.7.583.PubMedView ArticleGoogle Scholar
- Leontis NB, Stombaugh J, Westhof E: Motif prediction in ribosomal RNAs Lessons and prospects for automated motif prediction in homologous RNA molecules. Biochimie. 2002, 84: 961-973. 10.1016/S0300-9084(02)01463-3.PubMedView ArticleGoogle Scholar
- Schuwirth BS, Borovinskaya MA, Hau CW, Zhang W, Vila-Sanjurjo A, Holton JM, Cate JH: Structures of the bacterial ribosome at 3.5 A resolution. Science. 2005, 310: 827-834. 10.1126/science.1117230.PubMedView ArticleGoogle Scholar | <urn:uuid:7486faae-89b0-4d1e-9a2b-578d57406015> | 2.71875 | 2,418 | Truncated | Science & Tech. | 44.162852 | 95,503,539 |
Last updated: August 24, 2015
On July 27 the volunteers collected monarch eggs on milkweed leaves near the main parking area at Coldwater Spring. Mississippi River Biotechs and volunteers are currently caring for 7 caterpillars.
- Monarch caterpillars only eat plants in the Milkweed family (Asclepias Sp.)
- An egg is usually laid on the underside of a milkweed leaf
- At Coldwater Spring we have four species of milkweed: Common, Butterflyweed, Marsh, and Whorled.
- We are adding a milkweed and pollinator patch this fall for National Public Lands Day, September 26, 2015 - Volunteer opportunities are available!
Checkout the towering wildflowers on the hill overlooking the parking lot.
- Yellow giant hyssop is in the mint family, and has square stems. Leaves are arrowhead-shaped. Tiny yellow flowers in clusters are arranged on terminal spikes.
- Cut-leaf coneflower is also called green-headed coneflower. The leaves are deeply "cut", 3-5 parted and the central disk of the flower is green.
"One morning last week as I watered the sapling oak trees I saw a turkey and her brood of four chicks sitting at the base of this little tree.
Turkey nests can be as simple this shallow depression scratched into the ground."
Turkey Nesting Facts:
- Clutch Size: 4–17 eggs Number of Broods: 1
- Nestling Period: 1 day
- Egg Description: Pale yellowish tan, evenly marked with reddish brown or pinkish spots.
- Egg Length: 1.9–2.7 in
- Condition at Hatching: Well-developed and covered with tawny, brown, pinkish, and gray down. | <urn:uuid:ef18b312-a2be-45fa-b95e-31707e905333> | 3.0625 | 368 | News (Org.) | Science & Tech. | 58.103175 | 95,503,559 |
Share this article:
El Niño may make a comeback later this year, impacting the weather across the United States during fall and winter.
A March 9, 2017, report from NOAA’s Climate Prediction Center stated that there is a 50 to 55 percent chance for El Niño to develop between July and December. If El Niño develops, it could have implications on the upcoming hurricane season and the overall weather pattern across North America into next winter.
El Niño occurs when the water temperature in the Pacific Ocean near the equator are warmer than normal for an extended period of time.
While signs are pointing toward El Niño returning, it is not a guarantee.
“Transitioning out of winter can be very difficult for the weather models to handle, so you can get misdiagnosed in the months of February, March and April especially,” AccuWeather Lead-Long Range Meteorologist Paul Pastelok said.
This uncertainty is sometimes referred to as the "spring barrier," since this time of year is when weather models that help to forecast El Niño are typically least accurate.
However, confidence is slowly growing that El Niño will develop this summer. It is not expected to reach its peak until late in the fall or early winter. Even if it does develop in the summer, it may take until the fall before more significant weather impacts are seen in the U.S., according to Pastelok.
There can be a lag between when the ocean water temperatures climb, as El Niño develops, and the influence over the U.S. weather pattern, Pastelok said.
El Nino may suppress Atlantic hurricane season
The timing of the onset of El Niño may play a key role with how active the upcoming hurricane season is in the Atlantic Ocean.
During an El Niño year, the winds at the mid and upper levels of the atmosphere are not favorable for the development of tropical system in the Atlantic hurricane basin, Pastelok said.
These disruptive winds can limit the number of tropical systems that develop, leading to a below-normal year.
With El Niño potentially developing late in the summer or early in the fall, these disruptive winds would have more of an impact on the second half of the season, decreasing the frequency of tropical systems in late-September, October and November.
“If El Niño does come on the way that it’s showing on the weather models right now, it may shut the season off early,” Pastelok said.
Eastern United States may see a snowy winter
The strength of El Niño will determine the impacts that it has on the eastern U.S.
While it is unlikely that another "super El Niño" will unfold like the pattern two winters ago, there could be a weak to moderate El Niño during the upcoming fall and winter.
During a stronger El Niño, storm systems typically track across the southern U.S. and out to sea rather than tracking up the East Coast. This lowers the chance of a major winter storm, such as a nor’easter.
However, if the pattern is weaker, systems may track farther north and could move up the East Coast, resulting in snow when enough cold air is present.
What led to California's drought-busting rain this winter?
Winter 2016-17 goes down as 6th warmest on record in US; Storm parade nearly erases California drought
Prepare now for spring with 'AccuWeather Ready' weather preparedness information, tools
10 vegetables to plant in spring to kickstart your garden
“The weaker the El Niño, the more favorable for impactful storms and snow in the East next winter,” Pastelok said.
Thus, a weaker El Niño could spell above-normal snowfall for cities along the I-95 corridor next winter, including in New York City and Boston.
Another wet winter may lie ahead for California
This past winter unleashed drought-busting rain and snow to California, and El Niño could yield another wetter-than-normal winter for the state.
“An El Niño typically leads to more storms targeting California since the jet stream and resultant storm track dips southward across the state and pulls in tropical moisture,” AccuWeather Senior Meteorologist Kristina Pydynowski said.
Additional rounds of flooding similar to that of this past winter could ensue, but rainfall can also eliminate lingering drought conditions.
“It would be very beneficial for moisture to come from the Pacific Ocean right into extreme Southern California and western Arizona to moisten that area up to completely eliminate the drought that they’ve had,” Pastelok said.
El Niño-driven rain in this area could also help to replenish Lake Meade, the water reservoir created by the Hoover Dam. The water level on this lake has dropped over the past several years due to drought.
While another wet winter may unfold for California next year, it is not likely to be as wet as this past winter.
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.
Twelve people were injured when a flying lava bomb punctured the roof of a lava tour boat, causing a large hole in the vessel.
While Trump and Putin met for a summit in Helsinki, Finland, on Monday morning, a message about climate change was hung from a church by an environmental activist group.
En promedio, 37 niños mueren anualmente al ser olvidados dentro de un auto.
The tournament is being held in eastern Scotland, a region which has a history of extreme weather that can create chaos for golfers and spectators.
Following a push of dry air during the middle part of this week, a humid and rather wet weather pattern is forecast to evolve over the eastern third of the nation during the latter part of July.
The ongoing Kilauea volcano eruptions in Hawaii have led to the formation of a tiny, new piece of land made of lava, which was initially considered to be an island.
An organizing tropical threat will heighten the risk for flooding from the Philippines to Vietnam and Laos into midweek.
A grueling heat wave caused at least eight deaths across Japan since Saturday, and the dangerous conditions are not forecast to subside through the duration of the week. | <urn:uuid:a0ca1a8d-3cab-4ba7-9f38-818d8e51e913> | 3.375 | 1,309 | News Article | Science & Tech. | 44.341731 | 95,503,574 |
Whereas messenger RNAs transmit the genetic information required for protein synthesis, non-coding RNAs are functional molecules that are never translated into proteins and have important roles in diverse cellular processes. In human spermatozoa, these tiny RNAs are epigenetically regulated (by changes in the genome that do not alter the DNA sequence, such as DNA methylation) and play a critical role in male germline development. Importantly, these RNAs have also been detected in human cancer cells.
In a work published in the January 2014 issue of Epigenetics, which is entirely devoted to "Non-coding RNAs in Epigenetic Regulation," the researchers asked if in their natural functional context (the normal human testis) these small RNAs undergo aberrant epigenetic regulation, compromising their function and contributing to the transformation of cells into testicular tumor cells. The reported data suggest that epigenetic disruption of an entire small non-coding RNA pathway in human testis is indeed a hallmark for the development of testicular tumors.
For the full paper, visit the following link: https://www.landesbioscience.com/journals/epigenetics/article/27237/
To access all the articles in this Special Focus Issue on "Non-coding RNAs in Epigenetic Regulation," visit the following link: http://www.landesbioscience.com/journals/epigenetics/toc/volume/9/issue/1/
Andrew Thompson | EurekAlert!
Unique brain 'fingerprint' can predict drug effectiveness
11.07.2018 | McGill University
Direct conversion of non-neuronal cells into nerve cells
03.07.2018 | Universitätsmedizin der Johannes Gutenberg-Universität Mainz
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:9457e505-65e7-4586-ba30-1bd08baf2fc7> | 3.5625 | 947 | Content Listing | Science & Tech. | 34.154082 | 95,503,576 |
Lectures on Geodesics in Riemannian Geometry
by M. Berger
Publisher: Tata Institute of Fundamental Research 1965
Number of pages: 317
The main topic of these notes is geodesics. Our aim is 1) to give a fairly complete treatment of the foundations of Riemannian geometry through the tangent bundle and the geodesic flow on it and 2) to give global results for Riemannian manifolds which are subject to geometric conditions of various types; these conditions involve essentially geodesics.
Download or read it online for free here:
by Richard L. Bishop - arXiv
These notes on Riemannian geometry use the bases bundle and frame bundle, as in Geometry of Manifolds, to express the geometric structures. It starts with the definition of Riemannian and semi-Riemannian structures on manifolds.
by Ilkka Holopainen, Tuomas Sahlsten
Based on the lecture notes on differential geometry. From the contents: Differentiable manifolds, a brief review; Riemannian metrics; Connections; Geodesics; Curvature; Jacobi fields; Curvature and topology; Comparison geometry; The sphere theorem.
by David R. Wilkins - Trinity College, Dublin
From the table of contents: Smooth Manifolds; Tangent Spaces; Affine Connections on Smooth Manifolds; Riemannian Manifolds; Geometry of Surfaces in R3; Geodesics in Riemannian Manifolds; Complete Riemannian Manifolds; Jacobi Fields.
by John Douglas Moore - University of California
Foundations of Riemannian geometry, including geodesics and curvature, as well as connections in vector bundles, and then go on to discuss the relationships between curvature and topology. Topology will presented in two dual contrasting forms. | <urn:uuid:564faf52-843f-42e1-8164-5eba4bcc6ac0> | 2.5625 | 398 | Content Listing | Science & Tech. | 20.86 | 95,503,600 |
James Poulet's lab at the MDC uses advanced techniques to monitor the activity of networks of single sensory neurons in the brain. By listening in on hundreds of conversations, the scientists have discovered how a single signal from one cell manages to attract attention.
When we are awake, an incredible amount of sensory information flows into the brain, where it is filtered to distinguish important signals from all the noise. Crucial steps in this processing take place in the neocortex, which has a layered structure like six computer servers stacked on top of each other.
Sensory nerves throughout the body collect information and transmit it along their wire-like axons into specific layers of this structure. Inside the neocortex it jumps to other neurons, and if the signal is strong enough, they generate an action potential and transmit a signal of their own. This electrochemical charge races up their axons into other layers of the cortex and is ultimately transmitted to other regions of the brain.
Along the way the signal can be amplified by excitatory neurons such as pyramidal cells (PYRs) or dampened by inhibitory neurons such as SST and PV cells. Inhibition keeps a signal from spreading until it overloads the system – as seen in conditions like epilepsy. Strangely, many excitatory PYR cells fire infrequently, in single bursts of activity. Now James Poulet's lab at the MDC has discovered how these quiet neurons manage to make themselves heard. Their work appears in the current issue of Nature Communications.
Whole-cell measurements of input and output
Studying the effects of single "spikes" from PYR cells required listening in on their activity, as well as that of neighboring PV and SST neurons. The types can be distinguished by the molecules they produce, but scientists haven't had a full picture of how they interact with each other as signals move through the sensory cortex.
"Whole-cell recordings are an advanced method that can be performed in living mice that have been genetically modified," says Jean-Sebastian Jouanneau, a postdoc in Poulet's lab and a lead author on the paper. "We can now apply it to specific neurons that we have identified visually.
It's a unique approach that allows us to stimulate single neurons and monitor the tiny fluctuations in their electrical activity that generate action potentials. By stimulating the nerves one after another, and listening in on the network, we can check whether the cells are connected to each other and determine the effects a signal has."
The scientists carried out this procedure hundreds of times, breaking a record by monitoring four neurons simultaneously in each experiment. Putting all the data together required large-scale analysis by Jens Kremkow, a former lab member and also lead author on the paper.
A quiet voice that makes everything even quieter
The analysis produced some surprising results. A single spike from a PYR cell didn't provoke any activity in the other PYR cells or SST neurons it was attached to. But the PV neurons told a different story. The one-off signal from the PYR cell caused the PV neuron to fire – an amazingly efficient response.
The effects of this transmission were equally surprising. "The signal produced by the PV cell – after stimulation by the PYR cell – was passed on to target nerve cells and prevented them from generating action potentials of their own," Poulet says. "Those targets included PYR cells – the types of cells that had stimulated it in the first place! The result is a situation where one signal manages to silence all the neighbors."
The situation is a bit like a professor who comes into a classroom where people are chatting and shuffling papers around. If he starts speaking loudly, students often raise their own voices so that they can still hear themselves as well. But if he speaks very softly, they usually quickly quiet down – and may shush their neighbors – to hear what he is saying.
"We've seen this type of signal dampening before, but not in response to a single spike," Poulet says. "Observing this effect required studying the signal in an intact and active network. This could be an important mechanism that helps the brain filter subtle but important stimuli so that they will be heard despite the noise."
Jean-Sébastien Jouhanneau et al (2018): “Single synaptic inputs drive high-precision action potentials in parvalbumin expressing GABA-ergic cortical neurons in vivo”, Nature Communications. doi: 10.1038/s41467-018-03995-2
About the Max Delbrück Center for Molecular Medicine
The Max Delbrück Center for Molecular Medicine in the Helmholtz Association (MDC) was founded in Berlin in 1992. It is named for the German-American physicist Max Delbrück, who was awarded the 1969 Nobel Prize in Physiology and Medicine. The MDC's mission is to study molecular mechanisms in order to understand the origins of disease and thus be able to diagnose, prevent and fight it better and more effectively.
In these efforts the MDC cooperates with the Charité - Universitätsmedizin Berlin and the Berlin Institute of Health (BIH) as well as with national partners such as the German Center for Cardiovascular Research and numerous international research institutions. More than 1,600 staff and guests from nearly 60 countries work at the MDC, just under 1,300 of them in scientific research. The MDC is funded by the German Federal Ministry of Education and Research (90 percent) and the State of Berlin (10 percent), and is a member of the Helmholtz Association of German Research Centers.
Annette Tuffs | Max-Delbrück-Centrum für Molekulare Medizin in der Helmholtz-Gemeinschaft
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:29ac9729-51c0-4353-8f4a-76e30ff90a1c> | 3.90625 | 1,826 | Content Listing | Science & Tech. | 43.552823 | 95,503,605 |
By Mary MacDonald
Agendas and Sustainability considers the strategies used for devising international surroundings and improvement agendas and offers useful feedback for his or her destiny improvement and impact. A collaboration of the newest study from the Stockholm surroundings Institute and the Earth Council, the publication offers similarities and modifications in challenge definition, ambitions, rules, priorities and activities throughout 11 of the key agendas recommend for atmosphere and improvement after Rio. issues of divergence and parts of universal floor are investigated for over 30 setting and development-related subject matters, resembling biodiversity, intake styles, alternate, urbanization, inhabitants, schooling, deforestation and water assets.
provigil without prescription Read Online or Download Agendas for Sustainability: Environment and Development Agendas for the 21st Century (Routledge Sei Global Enviroment and Development Series) PDF
buy Lyrica 150mg Best environment books
Despite its ideal significance and the specter of its worldwide crash, biodiversity is still poorly understood either empirically and theoretically. This bold e-book provides a brand new, common impartial concept to provide an explanation for the starting place, upkeep, and lack of biodiversity in a biogeographic context.
in the past biogeography (the learn of the geographic distribution of species) and biodiversity (the examine of species richness and relative species abundance) have had mostly disjunct highbrow histories. during this e-book, Stephen Hubbell develops a proper mathematical conception that unifies those fields. whilst a speciation method is included into Robert H. MacArthur and Edward O. Wilson's now classical idea of island biogeography, the generalized concept predicts the lifestyles of a common, dimensionless biodiversity quantity. within the concept, this primary biodiversity quantity, including the migration or dispersal expense, thoroughly determines the steady-state distribution of species richness and relative species abundance on neighborhood to massive geographic spatial scales and non permanent to evolutionary time scales.
even supposing impartial, Hubbell's concept is however in a position to generate many nonobvious, testable, and remarkably exact quantitative predictions approximately biodiversity and biogeography. in lots of methods Hubbell's conception is the ecological analog to the impartial concept of genetic glide in genetics. The unified impartial conception of biogeography and biodiversity may still stimulate learn in new theoretical and empirical instructions via ecologists, evolutionary biologists, and biogeographers.
Submit 12 months observe: First released June eleventh 2012
China's large environmental demanding situations are major for us all. They have an effect on not just the well-being and health of China however the very way forward for the planet.
In this trailblazing booklet, famous China professional and environmentalist Judith Shapiro investigates China's fight to accomplish sustainable improvement opposed to a backdrop of acute rural poverty and hovering center classification intake.
Using 5 center analytical innovations to discover the complexities of this fight - the results of globalization, the demanding situations of governance; contested nationwide identification, the evolution of civil society and difficulties of environmental justice and fairness - Shapiro poses a few urgent questions:
• Do the chinese language humans have the appropriate to the better dwelling criteria loved within the built global?
• Are China's environmental difficulties so critical that they could shake the government's balance, legitimacy and keep watch over?
• To what quantity are China's environmental difficulties because of styles of Western intake?
• And in a global of accelerating limits on assets and toxins "sinks," is it even attainable to construct an equitable method within which humans get pleasure from equivalent entry to assets with no taking them from successive generations, from the bad, or from different species?
China and the planet are at a pivotal second; the trail in the direction of a extra sustainable improvement version remains to be open. yet - as Shapiro persuasively argues - making this selection would require humility, creativity, and a rejection of commercial as ordinary. The window of chance aren't open for much longer.
During this Very brief advent, Stephen Smith exhibits how the sector of environmental economics seems at how financial job and coverage can have an effect on the surroundings during which we are living. The publication discusses environmental matters together with pollutants keep an eye on, decreasing environmental harm, worldwide weather switch guidelines, questions on how we must always stability environmental and financial concerns, and what shape executive rules may still take.
The Manatee in Florida needs to be safe. crucial studying for Mammalogists with an services within the Manatee.
- Advances in energy, environment and materials science : proceedings of the International Conference on Energy, Environment and Materials Science (EEMS 2015), Guanghzou, P.R. China, 25-26 August, 2015
- Landscapes of Promise: The Oregon Story, 1800-1940
- Cleaning Printed Wiring Assemblies in Today’s Environment
- Environment and health in central and eastern Europe: a report for the Environmental Action Programme for Central and Eastern Europe, Volume 34
- Blackout: Coal, Climate and the Last Energy Crisis
Additional resources for Agendas for Sustainability: Environment and Development Agendas for the 21st Century (Routledge Sei Global Enviroment and Development Series)
Between Agenda 21 and Caring for the Earth, Agenda 21 focuses more specifically on using local government for local applications of Agenda 21. Caring for the Earth stresses making sustainable living a priority at the community level, although even stronger emphasis is given to individual commitments to lifestyle changes. Major points of comparison between the agendas Agenda 21 focuses specifically on its local application through local government, while Caring for the Earth presents a similar view of making sustainable living a priority at the community level without the emphasis on local government.
Youth ’92, noting the economic inequality between North and South resulting from colonization, the programmes of international financial institutions and high foreign debt, also proposes cancelling the foreign debt of developing countries, a policy not mentioned in Agenda 21. 23 AGENDAS FOR SUSTAINABILITY Agenda 21 and the Youth Action Guide recognize the interrelated nature of environment and development and emphasize the link between increased trade liberalization and better environmental management.
Democracy NGO Commitment: Expand Participatory Democracy, Appeal to Governments: Enhance and Promote Participatory Democracy Women’s Action Agenda 21 Democratic Rights, Diversity, Solidarity Youth ’92 Democracy and Participation Agenda Ya Wananchi All eleven agendas emphasize the need for greater participation in decisionmaking at various levels and on a large number of issues. Three agendas have separate sections which specifically address democracy. Youth ’92 and Agenda Ya Wananchi consider democracy and participation, while the Women’s Action Agenda 21 looks at democratic rights, diversity and solidarity. | <urn:uuid:1aa02ec8-5fe8-4f60-b5df-0ccd7d448c93> | 2.671875 | 1,355 | Product Page | Science & Tech. | 0.450261 | 95,503,613 |
Short-term meteorological data and tree growth rings have also been used to supplement the records of ceremonies.
Historical documents such as the records of rogativas (ceremonies with origins dating back to Roman agricultural rites) compiled at the Cathedral of Toledo and municipal churches, have allowed researchers to gain an insight into the climatological period between 1506 and 1900 in Toledo and Madrid, particularly in regard to extreme weather events such as droughts.
After processing this information, the scientists published their work in Global and Planetary Change. Their article shows that droughts in Spain throughout most of the 16th Century were infrequent and shorter than in subsequent periods. The period between 1676 and 1710 was characterised by lower hydric stress, and the 19th Century experienced a low frequency of droughts. However, “the most severe droughts were recorded during the period from the end of the 16th Century up until the 18th Century”, Juan I. Santisteban, one of the authors of the study and a researcher at the Complutense University of Madrid (UCM) tells SINC.
The researchers discovered that “droughts were more frequent and stronger than in other periods” in the centre of the peninsula during the Little Ice Age, a period covering the time period studied. Although drought intensity was similar to present-day levels, the study was unable to clarify whether current droughts last longer than previous ones, “even though the greater demand for water today makes the lack of water seem so severe”, says Santisteban.
The study also checked the results against those obtained from other records in the Mediterranean area. “Notable differences can be observed between the frequency and duration of droughts – we find rainy periods and droughts at the same time in different parts of the Iberian Peninsula and also differences between northern and southern parts,” points out Santisteban.
The combined analysis of this drought information and of atmospheric pressure at sea level – carried out by researchers from the UCM, the Geological and Mining Institute of Spain, and the University of Barcelona – shows that periods of frequent droughts coincide with positive phases of the North Atlantic Oscillation (NAO), which produces prolonged anti-cyclonic conditions in the Azores. However, they add that “the topography of the Iberian Peninsula could be largely responsible for much of the heterogeneity of the drought phenomenon”.
The Church, tracking the climate
Ceremonies carried out at the Cathedral of Toledo were controlled by strict protocols set by the Church, and varied according to the gravity of meteorological conditions. In Spain, the cathedral archives of many dioceses hold relatively continuous records from the 16th Century onwards.
The data on rogativas analysed by the scientists come from three sources – the 121 volumes of capitulary records from the Cathedral of Toledo, which record daily life from 1466 to 1599, the book started by Juan Bautista de Chaves Arcayos (who summarised the capitulary books from 1434 to 1599 and incorporated his own updates), and the 331 volumes of capitulary books (1464-1914), which fill in the gaps between the capitulary records.
This series of rogativas contains 341 prayers for rain, 36 pro-serenitate prayers for fine weather, and 94 Masses of thanks (ceremonies to celebrate the ending of the climatological phenomenon that had necessitated the rogativa). Many of the rogativas were part of Spring ceremonies.
SINC Team | alfa
Innovative genetic tests for children with developmental disorders and epilepsy
11.07.2018 | Christian-Albrechts-Universität zu Kiel
Oxygen loss in the coastal Baltic Sea is “unprecedentedly severe”
05.07.2018 | European Geosciences Union
A new manufacturing technique uses a process similar to newspaper printing to form smoother and more flexible metals for making ultrafast electronic devices.
The low-cost process, developed by Purdue University researchers, combines tools already used in industry for manufacturing metals on a large scale, but uses...
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
20.07.2018 | Power and Electrical Engineering
20.07.2018 | Information Technology
20.07.2018 | Materials Sciences | <urn:uuid:7e6bb9fa-4dc4-457c-8462-fda4f38e0c9e> | 3.90625 | 1,336 | Content Listing | Science & Tech. | 34.045801 | 95,503,633 |
There are two ways to transfer data. These are:
1. The diagram below displays the Drag and drop (DnD) functionality of Swing.
2. The diagram below displays the cut/copy and paste functionality of Swing. That is the clipboard transfer via cut/copy and paste. The path of the data is shown by the arrows.
To be more precise, first of all the bundling of data takes place into a package known as Transferable to begin Data Transfer. Then the data gets extracted by an object i.e. TransferHandler from the Transferable which is provided by the component. | <urn:uuid:b46f3a9a-90f3-487b-b05d-6f0d65376e1b> | 3.078125 | 124 | Documentation | Software Dev. | 65.712681 | 95,503,637 |
1 279,00 1 27900
Sendes vanligvis innen 7-15 dager
A glass is disordered material like a viscous liquid and behaves mechanically like a solid. A glass is normally formed by supercooling the viscous liquid fast enough to avoid crystallization, and the liquid-glass transition occurs in diverse manners depending on the materials, their history, and the supercooling processes, among other factors. The glass transition in colloids, molecular systems, and polymers is studied worldwide. This book presents a unified theory of the liquid-glass transition on the basis of the two band model from statistical quantum field theory associated with the temperature Green's function method. It is firmly original in its approach and will be of interest to researchers and students specializing in the glass transition across the physical sciences. It examines key theoretical problems of the liquid-glass transition and related phenomena. It clarifies the mechanism and the framework of the liquid-glass transition. | <urn:uuid:4e815285-9599-40c1-9f90-473fc61f08e9> | 2.859375 | 195 | Product Page | Science & Tech. | 31.574459 | 95,503,663 |
Another year of near-record global temperatures and the recent heat spike in major Australian cities should serve as warning of the vulnerability of populations to global warming, a leading climate researcher said.
The first complete datasets of land and sea surface temperatures worldwide, compiled by Europe's Copernicus Climate Change Service, indicate 2017 notched a fourth consecutive year of "exceptionally warm" conditions.
One set, by the European Centre for Medium-Range Weather Forecasts, placed last year just 0.1 degrees cooler than 2016, the hottest year on record.
2017 was warmer than 2015 and 2014 – two years that had previously set the high mark for global heat in successive years, the preliminary set showed.
The average air temperature at the surface exceeded 14.7 degrees, the Copernicus service said. The most above-average temperatures for the year were in the Arctic, with few land regions below average. (See chart below.)
A slew of agencies will release their findings on January 18, but the ranking for 2017 is "very likely to be in the top three", Blair Trewin, senior climatologist at the Bureau of Meteorology, said.
Hottest non-El Nino year
Andy Pitman, director the new ARC Centre of Excellence for Climate Extremes based at the University of NSW, said global temperatures shouldn't be close to records since last year did not have an El Nino to give them a boost.
"Normally El Ninos add three-tenths of a degree or so to the global mean, and we're not in one," Professor Pitman said.
"Climatologically, it's really quite surprising" 2017 was so warm, and the record for a non-El Nino year, he said.
The implications, though, are unclear.
One more favourable view is temperature increases linked to rising greenhouse gas emissions may be catching up to trend after a relatively slow stint of increases at the start of the century, he said.
A less promising outcome, however, might be the climate is more sensitive to warming than the Intergovernmental Panel on Climate Change has estimated. The current range is about 2-4.5 degrees warming for each doubling of carbon dioxide in the atmosphere.
"It's optimistic to think that the climate sensitivity is at the lower end of the range," Professor Pitman said. "It's likely to be on the mid- to high-end of the range – which isn't good."
The recent annual warming spurt implies the Paris climate goal of keeping warming to between 1.5 and 2 degrees of pre-industrial era levels "is virtually impossible", he said.
From averages to extremes
The weekend burst of heat across south-eastern Australia – including 47.3 degrees on Sunday in Penrith, the second hottest ever recorded in the Sydney Basin – underscores the risk of worse extremes when average temperatures rise.
While 2 degrees average global warming may not sound like a huge change, it implies land temperatures will rise about 3 degrees.
Those land regions in the mid-latitudes – where many Australian cities lie – may rise 4-5 degrees or more before extremes are taken into account, Professor Pitman said.
"If western Sydney warms by 4-5 degrees on the average in the summer, you're looking at extremes being 5-10 degrees higher than they currently are," he said.
A study published last October found Melbourne and Sydney could cop 50-degree days within decades if carbon emissions continued to rise.
The toll on the health of the population would mount as, if models predict, the length, frequency and intensity of heatwaves increase.
"What a few degrees increase in the average means is a dramatic escalation in the risk of extremely hot temperatures, lasting for longer periods of time," Professor Pitman said. "That places immense stress on emergency services, health services, the electrical grid, et cetera."
While western Sydney had posted one hotter day – 47.8 degrees back in January 1939 – the population was not highly reliant on air-conditioners with houses much better adapted to passive cooling back then.
"We are now adapting to the pleasure of air-conditioning – and it's totally dependent on the power grid surviving," he said.
A relationship banned under traditional law.
Our new podcast series from the team behind Phoebe's Fall | <urn:uuid:2dd3784d-1d26-4e54-bf4a-07d50e45f7d4> | 3.375 | 892 | News Article | Science & Tech. | 43.883096 | 95,503,667 |
Taking a page from Jonathan Swift's "Gulliver's Travels", a team of scientists has created malleable and microscopic self-assembling particles that can serve as the next generation of building blocks in the creation of synthetic materials.
"Our work turns the tiniest of particles from inflexible, Lego-like pieces into ones that can transform themselves into a range of shapes," explains Stefano Sacanna, an assistant professor in NYU's Department of Chemistry and the senior author of the paper, which appears in the journal Nature Communications. "With the ability to change their contours, these particles mimic alterations that occur in nature."
A team of NYU chemists has created malleable and microscopic self-assembling particles that can serve as the next generation of building blocks in the creation of synthetic materials. The research focused on engineering particles a micrometer in width -- about 1/200th the width of a strand of human hair (on which the particles [pink and blue] are placed in the above image).
Image courtesy of the Sacanna lab.
The research focused on engineering particles a micrometer in width--about 1/200th the width of a strand of human hair.
Specifically, it aimed to enhance the adaptability of colloids--small particles suspended within a fluid medium. Such everyday items such as paint, milk, gelatin, glass, and porcelain are composed of colloidal dispersions, but it's their potential to control the flow of light that has scientists focused on creating exotic colloidal geometries.
By triggering specific morphological changes in the singular colloidal unit, the Sacanna group hopes to advance colloidal crystal engineering.
The scientists discovered that, much like Gulliver tied down by Lilliputians, metallic particles encased in oil droplets were tethered by many chemical bonds. Breaking those tethers via a photocatalytic reaction--in which the absorption of light spurs a chemical response--caused the metallic particle to free itself, producing an overall shape change. In other words, shining a light on a simple crystal allowed the scientists to create a material that transforms its microstructure.
The study's other authors were: Mena Youssef and Theodore Hueckel, both NYU doctoral students, and Gi-Ra Yi, a professor at South Korea's Sungkyunkwan University.
This work was supported by the MRSEC Program of the National Science Foundation (DMR-1420073).
James Devitt | EurekAlert!
The secret sulfate code that lets the bad Tau in
16.07.2018 | American Society for Biochemistry and Molecular Biology
Colorectal cancer risk factors decrypted
16.07.2018 | Max-Planck-Institut für Stoffwechselforschung
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 | Transportation and Logistics
16.07.2018 | Agricultural and Forestry Science | <urn:uuid:cf1fcf71-9938-41b5-83c4-1bf3804a5f48> | 3.4375 | 1,163 | Content Listing | Science & Tech. | 38.120921 | 95,503,680 |
Brazilian artificial reservoirs are multi-purpose systems of great importance for the community since they are used for drinking water supply, energy generation and agricultural irrigation. Anthropogenic eutrophication is an environmental problem of special concern because it can restrict water use due to aquatic systems deterioration. Therefore, trophic state prediction is an important tool for the rapid detection of water quality decrease and the identification of priority areas where action is needed. Within this context, the aim of this research was to assess the role of TVS (total volatile solids) in predicting the trophic status of subtropical reservoirs. To achieve this goal, four stations in the Itupararanga Reservoir (São Paulo State, Brazil) were sampled during dry, intermediate and rainy periods to determine total suspended solids concentrations in different depths of the water column, in addition to other variables (e.g. phosphorus, nitrogen, chlorophyll-a). Through a linear regression between TSI (trophic state index) and the TVS concentrations, an equation relating these two variables was generated (R2 = 0.67). New TSI values (named TSIcalc) were calculated and analyzed against the observed ones (TSIobs, determined through the total phosphorus and chlorophyll-a concentrations). The results suggested that TVS may be considered an interesting variable to predict the trophic state of subtropical reservoirs.
Total volatile solids may aid in trophic state assessment in subtropical reservoirs
L. S. F. Pena, M. d. C. Calijuri, D. G. F. Cunha; Total volatile solids may aid in trophic state assessment in subtropical reservoirs. Water Science and Technology: Water Supply 1 May 2013; 13 (3): 808–815. doi: https://doi.org/10.2166/ws.2013.072
Download citation file: | <urn:uuid:9cd3e9b8-74e8-47e9-a655-849307281e3f> | 2.953125 | 395 | Academic Writing | Science & Tech. | 37.669599 | 95,503,696 |
Unlike the regular Fresnel expression node, the Fresnel function allows you to designate your own set of vectors used to calculate the equation, as well as make other adjustments to the blend.
Normal Vector (Vector3)
The first vector used in the Fresnel operation. Typically, this is the surface normal.
Camera Vector (Vector3)
The vector of the camera's direction.
Invert Fresnel (StaticBool)
This inverts the operation, reversing the way normals are calculated to yield results.
This value controls how quickly color falls off between the core and the edges.
Use Cheap Contrast (StaticBool)
This activates an internal CheapContrast function to boost the contrast of the Fresnel's result.
Cheap contrast dark (Scalar)
When using cheap contrast, this controls how much the dark value shows in the result. Has no effect when not using cheap contrast.
Cheap contrast bright (Scalar)
When using cheap contrast, this controls how much the bright value shows in the result. Has no effect when not using cheap contrast. | <urn:uuid:643baef9-56ce-44ef-a6e9-c4a587920c3a> | 2.6875 | 226 | Documentation | Software Dev. | 52.453485 | 95,503,715 |
Current eDNA sampling technologies consist mainly of do‐it‐yourself solutions. The lack of purpose‐built sampling equipment is limiting the efficiency and standardization of eDNA studies. So, Thomas et al. (a team of molecular ecologists and engineers) designed ANDe™.
In this video, the authors highlight the key features and benefits of ANDe™. This integrated system includes a backpack-portable pump that integrates sensor feedback, a pole extension with remote pump controller, custom‐made filter housings in single‐use packets for each sampling site and on-board sample storage.
The availability and accessibility of multispectral and radar satellite remote sensing (SRS) imagery are at an unprecedented high. However, despite the benefits of combining multispectral and radar SRS data, data fusion techniques, including image fusion, are not commonly used in biodiversity monitoring, ecology and conservation. To address this, the authors provide an overview of the most common SRS data fusion techniques, discussing their benefits and drawbacks, and pull together case studies illustrating the added value for biodiversity research and monitoring.
Technological advancements in the past 20 years or so have spurred rapid growth in the study of migratory connectivity (the linkage of individuals and populations between seasons of the annual cycle). A new article in Methods in Ecology and Evolution provides methods to help make quantitative comparisons of migratory connectivity across studies, data types, and taxa to better understand the causes and consequences of the seasonal distributions of populations.
In a new Methods in Ecology and Evolution video, Javier Puy outlines a new method of experimental plant DNA demethylation for ecological epigenetic experiments. While the traditionally-used approach causes underdeveloped root systems and high mortality of treated plants, this new one overcomes the unwanted effects while maintaining the demethylation efficiency. The authors demonstrate its application for ecological epigenetic experiments: testing transgenerational effects of plant–plant competition.
This novel method could be better suited for experimental studies seeking valuable insights into ecological epigenetics. As it’s based on periodical spraying of azacytidine on established plants, it’s suitable for clonal species reproducing asexually, and it opens the possibility of community-level experimental demethylation of plants.
Motion vision is an important source of information for many animals. It facilitates an animal’s movement through an environment, as well as being essential for locating prey and detecting predators. However, information on the conditions for motion vision in natural environments is limited.
To address this, Bian et al. have developed an innovative approach that combines novel field techniques with tools from 3D animation to determine how habitat structure, weather and motion vision influence animal behaviour. Their project focuses on Australia’s charismatic dragon lizards, and will place the animals’ motion displays in a visual-ecological context. The application of this approach goes well beyond this topic and the authors suggest the motion graphic technologies is a valuable tool for investigating the visual ecology of animals in a range of environments and at different spatial and temporal scales.
Measurements of morphological features are important for ecological studies, especially on free-ranging wild animal species. Conventionally, specimens either dead or in captivity are used for morphometric studies, which is difficult in the case of wild species for several reasons.‘In situ measurements of animal morphological features: a non-invasive method’ presents a new way to estimate an individual’s morphometric measurements using metadata from digital photographs.
Dr. Mylswamy Mahendiran and Mr. Mylswamy Parthiban, two of the authors of the article, discuss their paper in the video below. The authors cover the main messages of the article – including who will benefit from reading it; how their method is relevant to animal welfare and wildlife studies; the scope and utility of digital photographic advancements; and how other disciplines could use this method.
Understanding how animals perceive, learn and remember stimuli is critical for understanding both how cognition is shaped by natural selection, and how ecological factors impact behaviour.Unfortunately, the limited number of protocols currently available for studying insect cognition has restricted research to a few commercially available bee species, in almost exclusively laboratory settings.
In a new video Felicity Muth describes a simple method she developed with Trenton Cooper, Rene Bonilla and Anne Leonard for testing both lab- and wild-caught bees for their preferences, learning and memory. They hope this method will be useful for students and researchers who have not worked on cognition in bees before. The video includes a tutorial for carrying out the method and describes the data presented in their Methods in Ecology and Evolutionarticle, also titled ‘A novel protocol for studying bee cognition in the wild‘.
Occupancy surveys are widely used in ecology to study wildlife and plant habitat use. To account for imperfect detection probability many researchers use occupancy models. But occupancy probability estimates for rare species tend to be biased because we’re unlikely to observe the animals at all and as a result, the data aren’t very informative. | <urn:uuid:2a66246e-b320-49bc-958b-cc8df8e5afa8> | 3.171875 | 1,031 | Content Listing | Science & Tech. | 10.057978 | 95,503,727 |
New Adsorbent Selectively Captures Soluble Organic Contaminants in Water
Professor Cafer T. Yavuz and his team at the Graduate School of Energy, Environment, Water, and Sustainability (EEWS) have developed an adsorbent that can selectively capture soluble organic contaminants in water. This water treatment adsorbent is a fluorine-based nanoporous polymer that can selectively remove water-soluble micromolecules. It has the added advantage of being cheap and easily synthesized, while also being renewable.
Water pollution is accelerating as a result of global industrial development and warming. As new materials are produced and applied in the agricultural and industrial sectors, the types of contaminants expelled as sewage and waste water are also becoming diverse. Chemicals such as dyes and pesticides can be especially harmful because they are made up of small and highly soluble organic particles that cannot be completely removed during the water treatment process, ultimately ending up in our drinking water.
The current conventional water treatment systems utilize processes such as activated carbon, ozonolysis, and reverse osmosis membrane. These processes, however, are designed to remove larger organic molecules with lower solubility, thus removal of very small molecules with high solubility is difficult. In addition, these micromolecules tend to be charged, therefore are less easily separated in aqueous form. The research team aimed to remove these small molecules using a new adsorbent technology.
In order to remove aqueous organic molecular contaminants, the team needed an adsorbent that can adsorb micro-sized molecules. It also needed to introduce a chemical function that would allow it to selectively adsorb molecules, and lastly, the adsorbent needed to be structurally stable as it would be used underwater.
The team subsequently developed an adsorbent of fluorine-based porous organic polymer that met all the conditions listed above. By controlling the size of the pores, this adsorbent is able to selectively adsorb aqueous micromolecules of less than 1-2 nm in size.
In addition, in order to separate specific contaminants, there should be a chemical functionality, such as the ability to strongly interact with the target material. Fluorine, the most electronegative atom, interacts strongly with charged soluble organic molecules. The research team incorporated fluorine into an adsorbent, enabling it to separate charged organic molecules up to 8 times faster than neutral molecules.
The adsorbent developed by Professor Yavuz’s team has wide industrial applications. It can be used in batch-adsorption tests, as well as in column separation for size and charge-specific adsorption. Professor Yavuz stated that the charge-selective properties displayed by fluorine has the potential to be applied in desalination or water treatment processes using membranes.
Byun, J., Patel, H. A., Thirion, D., & Yavuz, C. T. (2016). Charge-specific size-dependent separation of water-soluble organic molecules by fluorinated nanoporous networks. Nature Communications, 7, 13377. doi:10.1038/ncomms13377
This article has been republished from materials provided by KAIST. Note: material may have been edited for length and content. For further information, please contact the cited source.
Analytical Tool Predicts Disease-Causing GenesNews
Predicting genes that can cause disease due to the production of truncated or altered proteins that take on a new or different function, rather than those that lose their function, is now possible thanks to an international team of researchers that has developed a new analytical tool to effectively and efficiently predict such candidate genes.
Single Gene Change in Gut Bacteria Alters Host MetabolismNews
Scientists have found that deleting a single gene in a particular strain of gut bacteria causes changes in metabolism and reduced weight gain in mice. The research provides an important step towards understanding how the microbiome – the bacteria that live in our body – affects metabolism.READ MORE | <urn:uuid:80f22d2e-a180-41a3-8f72-26d59901cce9> | 3.390625 | 832 | Truncated | Science & Tech. | 17.71138 | 95,503,755 |
What counts is only (the genetic) make-up
In classical biological taxonomy, animals and plants are identified by their external characteristics. "It is in species of a genus that resemble each other very closely, such as sedges, that definite identification can be a very long process," reported Prof. Quandt, Speaker for the botanical project within the GBOL Initiative. "In addition, we have to rely on competent experts here, who unfortunately are a dying breed nationally." Fully automated sequencing of DNA, however, allows identifying plants much faster. "Besides, we do not need flowering and complete plants," added Stefanie Winter, one of Prof. Quandt's doctoral candidates. "A tiny fragment, e.g., from a leaf, is sufficient for identifying the species based on its genetic markers."
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
20.07.2018 | Information Technology
20.07.2018 | Materials Sciences | <urn:uuid:2f4932f9-db16-4d37-bb5c-d88f077fb744> | 3.265625 | 745 | Content Listing | Science & Tech. | 36.351611 | 95,503,766 |
The varying scale and force of certain volcanic eruptions are directly influenced by the distribution of gases within magma inside a volcano's conduit, according to a new study.
Using state of the art equipment including UV cameras and electron microscopes, researchers from Plymouth University led a project to analyse the eruptive plumes and ash generated by Volcán de Colima, the most active volcano in the Americas.
Working alongside academics from the University of Cambridge and the Universidad de Colima in Mexico, they documented for the first time marked differences in the vesicularity, crystal characteristics and glass composition in juvenile material from the volcanic explosions.
The results led them to suggest that degassing which occurs during magma ascent leads to a build-up of both fast-ascending gas-rich magma pulses together with slow-ascending gas poor pulses within the volcano's conduit, which in turn determine the explosivity of any resulting eruption.
This particular type of volcanic activity is known as a Vulcanian explosion, and while they are explosive and short-lived, they often see large amounts of ash and magma fired more than 10km into the Earth's atmosphere.
Dr Paul Cole, Lecturer in Geohazards at Plymouth University, said: "Vulcanian explosions can be hazardous, and the purpose of this study is to try and get some understanding of what controls the explosions themselves. Volcan de Colima became active again in 2013, and our concern is that this may be the forerunner to something more serious as it has previously erupted every 100 years or so, with the last major eruption in 1913. With tens of thousands of people living in communities regularly evacuated because of the volcano, any increased knowledge of its activity could obviously have a marked effect."
Vulcanian explosions are among the most common types of volcanic activity observed at silicic volcanoes, and have also recently been in evidence at the Calbuco volcano in Chile.
Magma ascent rates have often been invoked as being the fundamental control on their explosivity, yet until now this factor is poorly constrained, partly due to the rarity of ash samples and low gas fluxes.
For this study, researchers employed a multi-disciplinary approach to address this, measuring sulphur dioxide fluxes emanating from the summit, as well as collecting ash for subsequent quantitative crystal and micro-geochemical analysis.
Dr Cole added: "This research has enhanced our knowledge, but we now need to explore whether the phenomena we have identified here are mirrored elsewhere. The current eruptions at Calbuco in Chile can also further our understanding of this type of activity and assist in our efforts to build a picture of how this gaseous interaction takes place, and the effects it has. Ultimately, it could help in our ongoing efforts to improve safety for communities living in the shadow of volcanoes."
Alan Williams | EurekAlert!
New research calculates capacity of North American forests to sequester carbon
16.07.2018 | University of California - Santa Cruz
Scientists discover Earth's youngest banded iron formation in western China
12.07.2018 | University of Alberta
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
17.07.2018 | Information Technology
17.07.2018 | Materials Sciences
17.07.2018 | Power and Electrical Engineering | <urn:uuid:caaa9220-7228-4041-9241-d0a2e047fda8> | 3.9375 | 1,214 | Content Listing | Science & Tech. | 32.363924 | 95,503,804 |
tcp_done - half-closes a TCP connection
#include <libdill.h> int tcp_done( int s, int64_t deadline);
TCP protocol is a reliable bytestream protocol for transporting data over network. It is defined in RFC 793.
This function closes the outbound half of TCP connection. Technically, it sends a FIN packet to the peer. This will, in turn, cause the peer to get EPIPE error after it has received all the data.
s: The TCP connection handle.
deadline: A point in time when the operation should time out, in milliseconds. Use the now function to get your current point in time. 0 means immediate timeout, i.e., perform the operation if possible or return without blocking if not. -1 means no deadline, i.e., the call will block forever if the operation cannot be performed.
This function is not available if libdill is compiled with --disable-sockets option.
In case of success the function returns 0. In case of error it returns -1 and sets errno to one of the values below.
struct ipaddr addr; ipaddr_local(&addr, NULL, 5555, 0); int ls = tcp_listen(&addr, 10); int s = tcp_accept(ls, NULL, -1); bsend(s, "ABC", 3, -1); char buf; brecv(s, buf, sizeof(buf), -1); tcp_close(s); tcp_close(ls);
brecv(3) brecvl(3) bsend(3) bsendl(3) now(3) tcp_accept(3) tcp_accept_mem(3) tcp_close(3) tcp_connect(3) tcp_connect_mem(3) tcp_listen(3) tcp_listen_mem(3) | <urn:uuid:f042f543-f3bb-4190-a017-a85cf3fc41e1> | 2.703125 | 403 | Documentation | Software Dev. | 78.28963 | 95,503,813 |
XPath is a W3C recommendation used to search and find parts of an XML document through a path expression. The elements or attributes that match the path expression will be returned for further processing by the invoking command, module, actor, or component.
In this post, I will explain about the basic concept of XPath via presentation slides. The presentation starts with a revisit to some of the XML key concepts. Subsequently, it shows sufficient elaboration of the basic concept of XPath. It concisely describes the key features of XPath that are worth knowing and practically useful especially when searching inside XML files.
The final part of the presentation consists of a sample project accompanied with some screenshots provided for readers to experiment with. In an upcoming post, I will show how the sample project can be converted into a Maven project for more convenient use and distribution.
You can download the slides from the following URL:
Xpath Basics (917 downloads)
Maven installation on Windows is very straightforward. Nonetheless, this post will provide sufficient elaboration to ensure a smooth installation. Following the installation, some configuration and testing tasks may need to be completed prior to creating the first Maven project.
A prerequisite for Maven installation is Java JDK. If you have not installed the Java SDK, you can refer to the installation procedure explained in this post.
The installation and configuration steps are executed in order as follows:
1. Download Maven zip package from the download page
Maven download page URL is http://maven.apache.org/download.cgi.
In this post, we will install and configure Maven 3.2.3. It can be anticipated that the installation procedure of the newer version of Maven will be quite similar with the one explained in this article.
2. Extract the zip into an installation directory of preference.
In this article, the directory contained in the extracted zip package is moved into “D:\Devs\DevHome\Maven\Bundle\apache-maven-3.2.3”. There is no strict rule regarding the installation directory. You can put the Maven directory in any directory of your choice. Continue reading
A lot of Java-based development tools require Java SDK as the dependency. This post will provide the guide on how to install Java SDK from Oracle on Windows, especially Windows 7. An additional configuration step is also included so that Java will be immediately ready for use by dependent applications.
Java SDK installation on Windows is apparently very straightforward. Oracle already provides a page explaining the Java SDK installation steps. This post focuses on step-by-step guide with necessary snapshot images to deliver better clarity on the installation process.
Java SDK Installation
1. Download Java SDK from the download page
Java SDK download page URL is http://www.oracle.com/technetwork/java/javase/downloads/index.html.
Oracle has released Java JDK 8 that provides improvement over the previous Java JDK 7. However, in this post we will choose Java JDK 7 since some popular libraries that we will use later may have not officially supported Java 8. To download JDK 7, click JDK download button from the Java SE 7uXX section and choose the binary version to download (32-bit or 64-bit). Continue reading | <urn:uuid:e4031e38-fdf1-4714-9374-8074140ff880> | 2.765625 | 683 | Truncated | Software Dev. | 47.579564 | 95,503,820 |
Insert statements have the following form:
INSERT INTO table (column1 [, column2, column3 ... ]) VALUES (value1 [, value2, value3 ... ])
The number of columns and values must be the same. If a column is not specified, the default value for the column is used. The values specified (or implied) by the
INSERT statement must satisfy all the applicable constraints (such as primary keys,
CHECK constraints, and
NOT NULL constraints). If a syntax error occurs or if any constraints are violated, the new row is not added to the table and an error returned instead.
INSERT INTO phone_book (name, number) VALUES ('John Doe', '555-1212');
Shorthand may also be used, taking advantage of the order of the columns when the table was created. It is not required to specify all columns in the table since any other columns will take their default value or remain null:
INSERT INTO table VALUES (value1, [value2, ... ])
Example for inserting data into 2 columns in the phone_book table and ignoring any other columns which may be after the first 2 in the table.
INSERT INTO phone_book VALUES ('John Doe', '555-1212');
A SQL feature (since SQL-92) is the use of row value constructors to insert multiple rows at a time in a single SQL statement:
INSERT INTO tablename (column-a, [column-b, ...]) VALUES ('value-1a', ['value-1b', ...]), ('value-2a', ['value-2b', ...]), ...
Example (assuming that 'name' and 'number' are the only columns in the 'phone_book' table):
INSERT INTO phone_book VALUES ('John Doe', '555-1212'), ('Peter Doe', '555-2323');
which may be seen as a shorthand for the two statements
INSERT INTO phone_book VALUES ('John Doe', '555-1212'); INSERT INTO phone_book VALUES ('Peter Doe', '555-2323');
Note that the two separate statements may have different semantics (especially with respect to statement triggers) and may not provide the same performance as a single multi-row insert.
To insert multiple rows in MS SQL you can use such a construction:
INSERT INTO phone_book SELECT 'John Doe', '555-1212' UNION ALL SELECT 'Peter Doe', '555-2323';
Note that this is not a valid SQL statement according to the SQL standard (SQL:2003) due to the incomplete subselect clause.
To do the same in Oracle use the DUAL table, which always consists of a single row only:
INSERT INTO phone_book SELECT 'John Doe', '555-1212' FROM DUAL UNION ALL SELECT 'Peter Doe','555-2323' FROM DUAL
A standard-conforming implementation of this logic shows the following example, or as shown above:
INSERT INTO phone_book SELECT 'John Doe', '555-1212' FROM LATERAL ( VALUES (1) ) AS t(c) UNION ALL SELECT 'Peter Doe','555-2323' FROM LATERAL ( VALUES (1) ) AS t(c)
Oracle PL/SQL supports the "INSERT ALL" statement, where multiple insert statements are terminated by a SELECT:
INSERT ALL INTO phone_book VALUES ('John Doe', '555-1212') INTO phone_book VALUES ('Peter Doe', '555-2323') SELECT * FROM DUAL;
In Firebird inserting multiple rows can be achieved like this:
INSERT INTO phone_book ("name", "number") SELECT 'John Doe', '555-1212' FROM RDB$DATABASE UNION ALL SELECT 'Peter Doe', '555-2323' FROM RDB$DATABASE;
Firebird however restricts the number of rows than can be inserted in this way, since there is a limit to the number of contexts that can be used in a single query.
INSERT statement can also be used to retrieve data from other tables, modify it if necessary and insert it directly into the table. All this is done in a single SQL statement that does not involve any intermediary processing in the client application. A subselect is used instead of the
VALUES clause. The subselect can contain joins, function calls, and it can even query the same table into which the data is inserted. Logically, the select is evaluated before the actual insert operation is started. An example is given below.
INSERT INTO phone_book2 SELECT * FROM phone_book WHERE name IN ('John Doe', 'Peter Doe')
A variation is needed when some of the data from the source table is being inserted into the new table, but not the whole record. (Or when the tables' schemas are not the same.)
INSERT INTO phone_book2 ( [name], [phoneNumber] ) SELECT [name], [phoneNumber] FROM phone_book WHERE name IN ('John Doe', 'Peter Doe')
SELECT statement produces a (temporary) table, and the schema of that temporary table must match with the schema of the table where the data is inserted into.
It is possible to insert a new row without specifying any data, using default values for all columns. However some databases would reject the statement if no data is given, such as Microsoft SQL Server, and in this case the
DEFAULT keyword can be used.
INSERT INTO phone_book VALUES ( DEFAULT )
Sometimes a databases also support alternative syntax for this, for example MySQL allows obmitting the DEFAULT keyword, and T-SQL can use
DEFAULT VALUES insteads of
DEFAULT keyword can also be used in normal insertion to explicitly fill a column using that column's default value:
INSERT INTO phone_book VALUES ( DEFAULT, '555-1212' )
What happens when a column does not specify a default value is database dependent. For example, MySQL and SQLite will fills in with blank value (except when in strict mode), while many other databases will reject the statement.
Database designers that use a surrogate key as the primary key for every table will run into the occasional scenario where they need to automatically retrieve the database generated primary key from an SQL INSERT statement for use in another SQL statements. Most systems do not allow SQL INSERT statements to return row data. Therefore, it becomes necessary to implement a workaround in such scenarios. Common implementations include:
SELECT * FROM NEW TABLE ( INSERT INTO phone_book VALUES ( 'Peter Doe','555-2323' ) ) AS t
SELECT EMPNO, HIRETYPE, HIREDATE FROM FINAL TABLE ( INSERT INTO EMPSAMP (NAME, SALARY, DEPTNO, LEVEL) VALUES('Mary Smith', 35000.00, 11, 'Associate') );
INSERT INTO phone_book VALUES ( 'Peter Doe','555-2323' ) RETURNING phone_book_id INTO v_pb_id
INSERT INTO phone_book VALUES ( 'Peter Doe','555-2323' ) RETURNING phone_book_id
If triggers are defined on the table on which the INSERT statement operates, those triggers are evaluated in the context of the operation. BEFORE INSERT triggers allow the modification of the values that shall be inserted into the table. AFTER INSERT triggers cannot modify the data anymore, but can be used to initiate actions on other tables, for example- to implement auditing mechanism.
Manage research, learning and skills at defaultLogic. Create an account using LinkedIn or facebook to manage and organize your Digital Marketing and Technology knowledge. defaultLogic works like a shopping cart for information -- helping you to save, discuss and share.Visit defaultLogic's partner sites below: | <urn:uuid:0e7c3c11-e4ef-42e2-97f2-43f0a989ae2d> | 3.234375 | 1,660 | Documentation | Software Dev. | 43.571385 | 95,503,837 |
An international team of researchers from the Centre for Genomic Regulation (CRG) in Barcelona, Spain, the Max Planck Institute for Molecular Genetics (MPIMG), Department of Vertebrate Genomics (H. Lehrach) in Berlin, the University of Bielefeld and further partners from academia and the private sector, have been able to sequence and analyse for the first time the sweet genes of beetroot.
The results of the study, that will be published next 18th December in Nature, shed also light on how the genome has been shaped by artificial selection.
What do foodstuff like muffins, bread or tomato sauce have in common? They all contain different amounts of white refined sugar. But, what perhaps may result amazing is that this sugar is probably sourced from a plant very similar to spinach or chard, but much sweeter: the sugar beet. In fact, this plant accounts for nearly 30% of the world’s annual sugar production, according to the Food and Agriculture Organization for the United Nations (FAO). Not in vain for the last 200 years, has it been a crop plant in cultivation all around the world because of its powerful sweetener property.
Sugar beet is the first representative of a group of flowering plants called Caryophyllales, comprising 11,500 species, which has its genome sequenced. This group encompasses other plants of economic importance, like spinach or quinoa, as well as plants with an interesting biology, for instance carnivorous plants or desert plants. 27,421 protein-coding genes were discovered within the genome of the beet, more than are encoded within the human genome. “Sugar beet has a lower number of genes encoding transcription factors than any flowering plant with already known genome”, adds Bernd Weisshaar, a principle investigator from Bielefeld University who was involved in the study. The researchers speculate that beets may harbor so far unknown genes involved in transcriptional control, and gene interaction networks may have evolved differently in sugar beet compared to other species.
Many sequencing projects nowadays targeted at the analysis of novel genomes also address the description of genetic variation within the species of interest. Commonly, “this is achieved by generating sequencing reads obtained from high-throughput sequencing technologies, followed by alignment of these reads against the reference genome to identify differences”, explains Heinz Himmelbauer, a principle investigator of this study. The current work, nevertheless, went one step further and generated genome assemblies from four additional sugar beet lines. This allowed the researchers to obtain a much better picture of intraspecific variation in sugar beet than would have been possible otherwise. In summary, 7 million variants were discovered throughout the genome. However, variation was not uniformly distributed: The authors found regions of high, but also of very low variation, reflecting both the small population size from which the crop was established, as well as the human selection, which has shaped the plants’ genomes.
Thanks to the sugar beet genome sequence made by the researchers and the associated resources generated, future studies on the molecular dissection of natural and artificial selection, gene regulation and gene-environment interaction, as well as biotechnological approaches to customize the crop to different uses in the production of sugar and other natural products, are expected to be held. “Sugar beet will be an important cornerstone of future genomic studies involving plants, due to its taxonomic position”, the authors claim.
Dr. Patricia Marquardt | Max-Planck-Institut
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
20.07.2018 | Information Technology
20.07.2018 | Materials Sciences | <urn:uuid:a2ff904b-10e1-4383-90bf-533d2bf5e676> | 3.453125 | 1,298 | Knowledge Article | Science & Tech. | 32.900552 | 95,503,853 |
This proposal, which endows dark matter particles with a rare form of electromagnetism, has been strengthened by a detailed analysis performed by a pair of theoretical physicists at Vanderbilt University: Professor Robert Scherrer and post-doctoral fellow Chiu Man Ho. An article about the research was published online last month by the journal Physics Letters B.
This is a comparison of an anapole field with common electric and magnetic dipoles. The anapole field, top, is generated by a toroidal electrical current. As a result, the field is confined within the torus, instead of spreading out like the fields generated by conventional electric and magnetic dipoles.
Credit: Michael Smeltzer, Vanderbilt University
"There are a great many different theories about the nature of dark matter. What I like about this theory is its simplicity, uniqueness and the fact that it can be tested," said Scherrer.
In the article, titled "Anapole Dark Matter," the physicists propose that dark matter, an invisible form of matter that makes up 85 percent of the all the matter in the universe, may be made out of a type of basic particle called the Majorana fermion. The particle's existence was predicted in the 1930's but has stubbornly resisted detection.
A number of physicists have suggested that dark matter is made from Majorana particles, but Scherrer and Ho have performed detailed calculations that demonstrate that these particles are uniquely suited to possess a rare, donut-shaped type of electromagnetic field called an anapole. This field gives them properties that differ from those of particles that possess the more common fields possessing two poles (north and south, positive and negative) and explains why they are so difficult to detect.
"Most models for dark matter assume that it interacts through exotic forces that we do not encounter in everyday life. Anapole dark matter makes use of ordinary electromagnetism that you learned about in school – the same force that makes magnets stick to your refrigerator or makes a balloon rubbed on your hair stick to the ceiling," said Scherrer. "Further, the model makes very specific predictions about the rate at which it should show up in the vast dark matter detectors that are buried underground all over the world. These predictions show that soon the existence of anapole dark matter should either be discovered or ruled out by these experiments."
Fermions are particles like the electron and quark, which are the building blocks of matter. Their existence was predicted by Paul Dirac in 1928. Ten years later, shortly before he disappeared mysteriously at sea, Italian physicist Ettore Majorana produced a variation of Dirac's formulation that predicts the existence of an electrically neutral fermion. Since then, physicists have been searching for Majorana fermions. The primary candidate has been the neutrino, but scientists have been unable to determine the basic nature of this elusive particle.
The existence of dark matter was also first proposed in the 1930's to explain discrepancies in the rotational rate of galactic clusters. Subsequently, astronomers have discovered that the rate that stars rotate around individual galaxies is similarly out of sync. Detailed observations have shown that stars far from the center of galaxies are moving at much higher velocities than can be explained by the amount of visible matter that the galaxies contain. Assuming that they contain a large amount of invisible "dark" matter is the most straightforward way to explain these discrepancies.
Scientists hypothesize that dark matter cannot be seen in telescopes because it does not interact very strongly with light and other electromagnetic radiation. In fact, astronomical observations have basically ruled out the possibility that dark matter particles carry electrical charges.
More recently, though, several physicists have examined dark matter particles that don't carry electrical charges, but have electric or magnetic dipoles. The only problem is that even these more complicated models are ruled out for Majorana particles. That is one of the reasons that Ho and Scherrer took a closer look at dark matter with an anapole magnetic moment.
"Although Majorana fermions are electrically neutral, fundamental symmetries of nature forbid them from acquiring any electromagnetic properties except the anapole," Ho said. The existence of a magnetic anapole was predicted by the Soviet physicist Yakov Zel'dovich in 1958. Since then it has been observed in the magnetic structure of the nuclei of cesium-133 and ytterbium-174 atoms.
Particles with familiar electrical and magnetic dipoles, interact with electromagnetic fields even when they are stationary. Particles with anapole fields don't. They must be moving before they interact and the faster they move the stronger the interaction. As a result, anapole particles would have been have been much more interactive during the early days of the universe and would have become less and less interactive as the universe expanded and cooled.
The anapole dark matter particles suggested by Ho and Scherrer would annihilate in the early universe just like other proposed dark matter particles, and the left-over particles from the process would form the dark matter we see today. But because dark matter is moving so much more slowly at the present day, and because the anapole interaction depends on how fast it moves, these particles would have escaped detection so far, but only just barely.
The research was funded in part by Department of Energy grant DE-FG05-85ER40226.
David Salisbury | Vanderbilt University
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
20.07.2018 | Materials Sciences | <urn:uuid:084fad4b-5430-491b-a1a1-61e7ff185b5b> | 3.734375 | 1,676 | Content Listing | Science & Tech. | 32.132062 | 95,503,854 |
Conceptual and Philosophical Problems of Quantum Mechanics
In the preceding chapters we have tried to develop the conceptual basis of quantum mechanics. In addition, various exercises have demonstrated how quantum theory can be used to solve real physical problems. Of course, these problems represent only a small fraction of the many applications of quantum mechanics; numerous experimental results involving physics and chemistry can be explained successfully by adopting this theory. Up to now, no prediction made by quantum mechanics has been disproved experimentally. In spite of this success, conceptual problems of the theory exist; in fact, there have been many attempts to interpret quantum mechanics in a new way or even to replace it by another theory based on a more obvious conceptual and philosophical foundation.
KeywordsWave Function Quantum Mechanic Hide Variable Spin Component Spin Vector
Unable to display preview. Download preview PDF.
- 1.In conceiving this chapter, we were guided by similar discussions by A.I.M. Rae in his book: Quantum Mechanics (McGraw-Hill, London 1981); M. Jammer: The Philosophy of Quantum Mechanics: The Interpretations of Quantum Mechanics in Historical Perspective (Wiley, New York 1974).Google Scholar
- 3.D. Bohm: Quantum Theory (Prentice-Hall, Englewood Cliffs, NJ 1951) pp.614–622.Google Scholar
- 4.J.S. Bell: Physics 1, 195 (1965).Google Scholar
- 4a.The following synoptic article can be recommended: J.F. Clauser, A. Shimony: “Bell’s Theorem: Experimental Tests and Implications”, Rep. Prog. Phys. 41, 1881 (1978). We also mention a more popular article by B. d’Espagnat: “The Quantum Theory and Reality”, Scientific American Vol. 241, No.11, 128 (1979).ADSCrossRefGoogle Scholar
- 5.Further information is given in the article by Clauser and Shimony cited above (see footnote 4). A new experiment was done by W. Perrie, A.J. Duncan, H.J. Beyer, and H. Kleinpoppen, and reported on in Phys. Rev. Lett. 54, 1790 (1985).Google Scholar
- 6.F.J. Belinfante: Measurement and Time Reversal in Objective Quantum Theory (Pergamon, Oxford 1978).Google Scholar | <urn:uuid:62ce22c5-c65d-458e-960c-dfd4c73e40b6> | 2.625 | 508 | Truncated | Science & Tech. | 56.692013 | 95,503,872 |
In this article we develop a mathematical method based on image analysis to measure the textural properties of heavy minerals in fluvial, eolian-dune, and beach sediments throughout the 1800-km-long Orange cell of littoral sand transport, the longest documented so far on our planet. We analyzed the grain size and shape of 12,700 grains, including all major heavy-mineral species contained in 22 selected samples collected along the Atlantic coast, from Namibia to southern Angola. In this unique natural laboratory, where the Orange River represents a single dominant sediment source characterized by diagnostic compositional fingerprints, hyperarid climate ensures limited chemical alteration of even unstable ferromagnesian minerals.
This case study led us to: a) monitor changes in grain size and roundness of various detrital minerals during ultralong transport in high-energy shallow-marine and eolian environments; b) determine the relative durability of various detrital minerals to mechanical wear as a function of their mineralogical properties (e.g., hardness, cleavability); c) compare roundness of grains in sands of different facies to establish the relative efficiency of mechanical processes as a function of depositional environment and transporting medium (i.e., water versus air); d) compare roundness of the same detrital species in beach deposits enriched in heavy minerals to different degrees and evaluate whether rounded grains are preferentially entrained or left behind during high-energy storm events; e) test the use of textural properties to distinguish between coarser or angular grains of local provenance from smaller or rounded grains derived from distant sources. The rigorous definition of particle shape and the measurement of grain roundness is a necessary step to achieve a full understanding of sedimentary processes, evaluate mechanical effects during long-distance transport, challenge untested assumptions, and obtain useful complementary information on sediment provenance. | <urn:uuid:b4d69122-e768-489b-960d-a629431a1d43> | 3.0625 | 383 | Academic Writing | Science & Tech. | -1.083258 | 95,503,882 |
The descriptor was part of the implementation, not part of the language.
Shmuel (Seymour J.) Metz
From: IBM Mainframe Assembler List <ASSEMBLER-LIST@listserv.uga.edu> on behalf
of Robin Vowels <robi...@dodo.com.au>
Sent: Thursday, February 1, 2018 10:09 PM
Subject: Re: Fair comparison C vs HLASM
From: "Paul Raulerson" <paul.rauler...@me.com>
Sent: Friday, February 02, 2018 12:55 AM
> And as already been noted, C was first compile on a PDP-7, which had a simple
> instruction set but
> was most definitely a CISC machine too. ;)
> It also explains one of the reasons why strings in C are null terminated.
> There were two modes of thought back in those days, ‘Pascal’ strings,
> which have the string size encoded in a single byte at the start of the
> and ‘C’ strings, which terminate a string with a NULL.
And PL/I strings, which used a descriptor in which the length up to 32767
> Pascal string length was obviously limited by the max value of a byte -
The length was not embedded in the langage; it was an arbitrary limit
imposed by the implementer.
They could have, for example, used 2 bytes at the start of the string.
> null terminated strings could be just about any possible size.
Yes, but with two disadvantages -- 1. if you wanted to know the length
of the string, it was necessaary to search the entire string.
2. A byte of zero could not be part of the string -- completely
useless when processing arbitrary data (such as image data,
and compressed data).
> Record eliminators of course, are an entirely different thing,
> but a C string could easily be a few thousand bytes long.
> Handy indeed for things like text processing, which is what the AT&T
> guys were selling Unix and C to their bosses for.
This email has been checked for viruses by Avast antivirus software. | <urn:uuid:80e9a4e4-c18b-454b-a5bd-9fbc0f41fe63> | 2.53125 | 475 | Comment Section | Software Dev. | 71.000677 | 95,503,913 |
|Right ascension||17h 46m 15.2s|
|Declination||-28° 49′ 49″|
|Type of object||Emission nebula|
|Distance from Earth||25,000 ly|
The Pistol nebula is an emission nebula in the constellation of Sagittarius. The first images of the nebula produced in the 1980s were of low resolution and appeared similar to a pistol, giving the nebula its name. The nebula is known for housing one of the most luminous stars known, the Pistol star, which is believed to be well over million times brighter than the Sun. The gas composing the nebula is thought to have been ejected by the star.
Properties and Structure
The nebula has a roughly rectangular shape, with dust and gaseous material present in two shells concentric with the Pistol star. This material is thought to have been blown off of the Pistol star by powerful stellar winds around 4,000-6,000 years ago. The nebula contains (excluding the Pistol star) around 9.3 solar masses of material. The larger of the two shells is thought to be 4 light years across and is currently expanding at 60 km/s. The nebula is ionized by Wolf-Rayet stars in the Quintuplet Cluster as well as their strong stellar winds.
The Pistol star, designated V4647 Sagittarii, is a blue hypergiant and a candidate luminous blue variable or cLVB. Discovered by Don Figer in the 1990s it is one of the brightest known stars, specifically at least 106.6 times brighter than the Sun. For a comparison, it radiates the same amount of energy in 20 seconds as the Sun does in an entire year. This results in an extraordinarily strong stellar wind, some 10 billion times more powerful than is outputted by the Sun and travels at 95 km/s. It must be observed in the infrared region of the electromagnetic spectrum due to interstellar dust surrounding the star. If it were not for the dust, it would appear as a fourth magnitude star even though it is over 25,000 light years away.
It is thought to weigh more than 100 solar masses but may have been composed of more than 200 solar masses of material in the past, much of it ejected into the nebula. However estimates vary with some putting it lower at 26.5 solar masses. Unsurprisingly, the star itself is physically very large; its radius is greater than the distance between the Earth and the Sun or 93 million miles. The star possess a temperature of 11,800 k.
- Pistol nebula from the SIMBAD Astronomical Database
- A Brilliant Star in Milky Way's Core from nasa.gov
- Pistol Star and Nebula from constellation-guide.com
- Figer, D., Morris, M., Geballe, T., Rich, R., Serabyn, E., McLean, I., Puetter, R. and Yahil, A. (1999). High-Resolution Infrared Imaging and Spectroscopy of the Pistol Nebula: Evidence for Ejection. The Astrophysical Journal, 525(2), pp.759-771. arXiv:astro-ph/9906479
- The Pistol Nebula from nasa.gov | <urn:uuid:6ea1ecc3-4650-496d-9671-d5e4336ff063> | 3 | 679 | Knowledge Article | Science & Tech. | 65.9945 | 95,503,922 |
HIDDEN DETAILS The sun’s corona is on full display in this composition of 161 photographs taken from Mitchell, Ore., during the August 21, 2017, solar eclipse. The research team behind this image used a special spectrometer to gain new insight into the corona’s motion.
© 2017 Miloslav Druckmüller, Peter Aniol and Shadia Habbal
LEESBURG, Va. — Astronomers watching the 2017 solar eclipse from the ground and from the air witnessed new, tantalizing features of the sun’s outer atmosphere.
Three teams have recently presented their first science results from the Great American Eclipse. Combined, the findings could help disentangle lingering solar puzzles, such as how bursts of plasma leave the sun, why the outer atmosphere, the solar corona, is so well organized and what is the nature of the corona’s magnetic field.
While thousands of eclipse watchers gathered across the country last August armed with special glasses and cameras, solar physicists Adalbert Ding and Shadia Habbal and their colleagues set up a specially designed spectrometer in Mitchell, Ore. (That was one of four sites from which their team monitored the eclipse.) The team had used an earlier version of the instrument, which takes in specific wavelengths of light that can trace different coronal temperatures, to watch a solar eclipse in March 2015 from Svalbard, Norway.
In both 2015 and 2017, the scientists observed evidence of relatively cool blobs of gas embedded in hot plasma in the outer corona. (The sun’s surface simmers at about 6000° Celsius, but its corona roasts at millions of degrees — and no one knows why.) Ding, of the Institute for Optics and Atomic Physics in Berlin, and Habbal, of the University of Hawaii in Honolulu, measured wavelengths of light emitted by atoms and charged particles called ions in the corona, as a proxy for the plasma’s heat.
To the researchers’ astonishment, they saw blobs of plasma during both eclipses that had maintained temperatures as low as 20,000° C embedded within material in the corona that was as hot as 3.7 million degrees Celsius, Ding said at the Triennial Earth-Sun Summit on May 23. “We were very surprised,” Ding says. He thinks the cooler material may be trapped within plasma bubbles and can’t get out. “The stunning thing is that they survive.”
The team also measured solar material’s Doppler shift, or the change in wavelength as the material moved toward or away from Earth. The shifts suggested that the scientists had caught a huge bubble of plasma erupting off the sun’s surface and fleeing out into space in 2015 (SN Online: 6/16/17). At the time, they thought seeing such an explosion, called a coronal mass ejection, was just luck.
If so, their luck held for the 2017 eclipse. The researchers haven’t finished processing all of their data yet, but preliminary results showed uncharged hydrogen and helium atoms fleeing the sun as far out as 3.5 solar radii from the edge of the sun’s bright disk, at speeds of about 600 kilometers per second.
In another talk at the meeting, solar physicist Amir Caspi of the Southwest Research Institute in Boulder, Colo., presented results from a different vantage point: a WB-57F aircraft flying at about 15 kilometers in altitude.
Caspi’s team was trying to see signs of magnetic waves called Alfvén waves rippling through the outer corona. Simulations of the plasma in the corona “lead you to this Velcro-looking thing, a tangled snarled mess,” Caspi said. “In fact, that’s not what we see.” Alfvén waves could smooth out the snarls, which could help explain why the material there is so neatly organized (SN Online: 8/17/17). What’s more, the waves may contribute to the mysterious coronal heating. So Caspi’s colleagues flew telescopes on a pair of NASA’s high-altitude aircraft during the eclipse to look for these waves.
The results were mixed, Caspi admits, in part because the telescopes were not designed for this type of science. NASA originally commissioned them to monitor shuttle launches for issues after the space shuttle Columbia disaster in 2003 (SN: 2/8/03, p. 83).
“Our mission was the first attempt to use them for astronomy,” Caspi says.
The telescopes saw some motion in the corona that could have been waves — or could have been jitter from the planes’ motion. “They’re tantalizing, they’re definitely not random,” Caspi said. “But we don’t know yet whether this is an artifact of the corrections we had to make, or if this is really on the sun.”
The team also captured an image of the corona in infrared wavelengths, which the researchers think is the first image of its kind. Eventually, such infrared measurements could help scientists measure the corona’s magnetic field, which governs most of the corona’s behavior but has never been measured directly (SN Online: 8/16/17).
In another experiment, solar physicist Jenna Samra of Harvard University and her colleagues were on the lookout for certain infrared wavelengths in the corona that were expected to be bright enough to see from the ground.
The team measured five wavelengths, one of which had never been seen before, the team reports in the April 1 Astrophysical Journal Letters. Solar physicist and study coauthor Philip Judge of the High Altitude Observatory in Boulder had predicted in 1998 that those wavelengths, which are especially sensitive to the magnetic field, should be visible in the corona. The results can help plan future observations with the Daniel K. Inouye Solar Telescope, currently under construction in Maui, Hawaii.
Judge and other team members observed the eclipse from Casper, Wyo., and saw some of the same wavelengths (SN Online: 8/21/17), although water in Earth’s atmosphere absorbed some of the light.
Samra, however, observed the eclipse from a plane, a Gulfstream V aircraft at an altitude of 14.3 kilometers. “It was a one-of-a-kind experience. I wouldn’t trade it,” she says. “But in the moment it was terrifying, honestly.” | <urn:uuid:457240f1-3453-453a-b412-def141b6c434> | 3.359375 | 1,378 | News Article | Science & Tech. | 52.498322 | 95,503,926 |
New Celestial Reference System
The IAU (1976) System of Astronomical Constants, the FK5 and new lunar and planetary theories are being introduced in 1984. The investigation and planning for the transition has revealed the complex interdependencies between observational techniques and the reference systems, and their strong link to the rotating and orbiting Earth. The inaccuracies in our knowledge of the star positions, astronomical constants and the rotation and motion of the Earth are embedded in subtle ways in the observations and the reference coordinate systems. For example, the FK4 reference system in 1950.0 coordinates rotates with respect to an inertial system. Details are given for the conversion to the new system.
The concepts for a future reference system are developed, based on separating the real motions involved such that observations from various moving platforms can be related to the appropriate coordinate system, without involving motions which are not intrinsically involved in the observations. Therefore, reference systems determined or utilized in space, while affected by aberration and parallax, would logically be defined with no dependence on precession, nutation, polar motion, or Universal Time, which are all concerned with motions of the Earth’s surface.
KeywordsReference System Proper Motion Referenee System Star Position Astronomical Constant
Unable to display preview. Download preview PDF.
- Eichhorn, H. 1979, Prochazka, F. V.,and Tucker, R.H. ed., Institute of Astronomy, Vienna, p. 391-410.Google Scholar
- Fricke, W. 1975, IAU Colloq. No. 26, Kolaczek B., and Weiffenbach, G. ed., Warsaw, Poland.Google Scholar
- Fricke, W. 1980, private communication.Google Scholar
- Guinot, B. 1979, IAU Symp. 82, McCarthy, D.D. and Pilkington, J. D. H. ed., D. Reidel Publ., Dordrecht, p. 7-18.Google Scholar
- Kovalevsky, J. 1979, IAU Symp. 82, McCarthy, D.D. and Pilkington, J. D. H. ed., D. Reidel Pubi., Dordrecht, p. 151-163.Google Scholar
- Murray, C.A. 1979, IAU Symp. 82, McCarthy, D.D. and Pilkington, J. D. H. ed., D. Reidel Publ., Dordrecht, p. 165-167.Google Scholar
- Wade, C. M. 1976, VLA Scientific Memoran3um 122.Google Scholar
- Wade, C. M. 1977, Transactions of the IAU, Volume XVI B, D. Reidel Publ., Dordrecht.Google Scholar
- Wade, C. M. 1980, Transactions of the IAU, Volume XVII B, D. Reidel Publ., Dordrecht.Google Scholar | <urn:uuid:aa37d962-ffd2-4226-9fd0-2ad55a5b2ae8> | 2.609375 | 624 | Truncated | Science & Tech. | 64.797493 | 95,503,936 |
The oceans don't have it too easy these days. There's overfishing, dying coral reefs, warming temperatures, and, to top it all off, an excess of plastic polluting the waters. Humans dump more than 8 million tons of plastic into our oceans every year, and the problem is only getting worse. We produce nearly 300 million tons of plastic every year, half of which is for single use, and most of the plastic we've ever produced is still around today. Which means more will keep to flowing into the oceans.
To combat this problem, one organization has invented the "seabin" to collect plastics of all sizes in the ocean, from bottles to debris. It can even collect oil. And the first one has been installed in Portsmouth Harbor in the U.K.
Essentially a trashcan-sized bin composed of a large fiber net and a dock-based pump, the seabin works by creating a flow of water that pulls any surrounding trash into the body of the bin to be caught in the net. It can catch about 3.3 pounds of plastic per day, with the ability to hold up to 26.5 pounds at full capacity. It is estimated each bin can pull about half a ton of debris out of the ocean every year, equivalent to 20,000 bottles or 83,000 plastic bags.
“Sure, we can’t catch everything right now, but it’s a really positive start,” the device’s creators, Pete Ceglinski and Andrew Turto, told the Huffington Post. “It’s a big mission, but it can be done. In fact, we’re doing it right now.”
The Australian creators, who founded the Seabin Project organization, were inspired to create the seabin after learning that existing solutions to pull trash out of the ocean, such as boats that drive around harbors, didn't work. But their seabin concept has proven so successful that they've raised $260,000 on Indiegogo to fund its creation. Now, if the U.K. pilot goes well, the product will go to market itn November of this year.
These seven Etsy shops from around the world offer an impressive range of cruelty-free products you can feel good about putting on your face.
A new report shares why decentralized energy grids will power the homes of the future and make a major difference in the lives of those in developing countries currently with limited or zero access to electricity.
Starbucks and McDonalds are working together to rethink to-go cups and inviting others to join them in creating eco-friendly packaging in an effort to reduce waste and environmental impact.
A new report finds that meat and dairy producers are on track to surpass the oil industry's greenhouse gas emissions. | <urn:uuid:cc237323-60a6-45c2-8e9f-d661fc867323> | 2.703125 | 573 | News Article | Science & Tech. | 61.638826 | 95,503,938 |
You are here: Home Environment Climate Change The Impact of Glacial Change in the Himalayas The Impact of Glacial Change in the Himalayas Could the glaciers melting in the Himalayans be a positive thing? by Chris Keenan September 25, 2012, 2:00 am The Himalayas are home to over a thousand glaciers, and these slow moving ice masses provide a significant portion of the water for the people that live in the area. In both the central and eastern parts of the region, the glaciers are melting, mimicking a problem faced in many other areas. However, if you look west, the glaciers seem to be doing well and might actually be getting bigger, according to information that was just released by the National Research Council. The National Research Council focused their attention on the Hindu Kush-Himalayan region, an area that spans eight Asian countries and is home to some of the most prominent rivers in the world, include the Ganges and Yangtze. They are particularly interested in determining how glacier activity might impact the local people, rivers and water sources. Previously, several reports came out that raised concerns about the diminishing size of the glaciers; the newest one reviews a few issues but also discusses potential solutions. The Situation In The East In the east, and along the Tibetan Plateau, glaciers are shrinking. The climate is hotter than it used to be, particularly in areas where black carbon and desert dust are prominent. Still, while the water supply may be slightly unstable due to population increases and other factors, it will probably be many years before the impact of the glacier melt is truly realized. This is partially due to the fact that both snowmelt and monsoon precipitation factor largely into how much water is available for use. Certain places, particularly at high elevations, may see changes related to glacier melting sooner, though, especially during dry season. What The Future Holds During the next thirty years or so, glacial melting could (literally) be a lifesaver for the people of the Himalayas. If there is a severe drought or another environmental catastrophe, glacial ice has the potential to make a huge difference in the water levels of the rivers and streams in the area. As a result, the individuals living there could survive a very trying time that ordinarily would have caused a substantial loss of life. It is important, however, that everyone does their part to try and slow down global warming so that glaciers will be around for many years to come. Products that help harness renewable energy resources, like solar panels, can help to achieve this goal. Solar panel costs and prices have dropped tremendously in the past few years and panel prices continue to fall, often lowering your energy costs, reducing your electricity bill, and saving you a lot of cash. There are many advantages to solar energy, which makes getting solar power seem like a no-brainer today — and then there are also solar water heaters. Learn more about solar power and stop procrastinating today on this important matter. Getting a home energy audit in general is a good idea as well, as is switching to an electric car — there are now 13 fully electric cars on the US market and another 17 plug-in hybrid electric cars. Keep an eye on rankings of the best electric cars, electric car sales, electric car prices, electric trucks, EV charging in your area, and what’s around the corner in order to clean your transportation vehicles as quickly as possible for your needs. Flexible management is another key to successfully adjusting to the glacial change. Himalayan glacier-fed stream photo via Shutterstock See more Previous article Comfort Food: on Crisis, Resilience, and Unexpected Benefits of Conscious Eating Next article Prop 37 CA Right to Know Fundraiser…in New York? Written by Chris Keenan Chris Keenan is a green and general blog writer. He also maintains a personal cooking blog: http://thekeenancookbook.com/ Leave a Reply Cancel reply Your email address will not be published. Required fields are marked *Comment Name * Email * Website Save my name, email, and website in this browser for the next time I comment. Upload a photo / attachment to this comment (PNG, JPG, GIF - 6 MB Max File Size): (Allowed file types: jpg, gif, png, maximum file size: 6MB. | <urn:uuid:2e30fbe4-654a-4c0a-8889-601326b81ecc> | 3.59375 | 881 | Personal Blog | Science & Tech. | 38.048414 | 95,503,951 |
ICommand is often used in the MVVM design pattern to allow the View to trigger business logic defined in the ViewModel. This allows for easier maintenance, unit testing, and the ability to reuse ViewModels across different UI frameworks. Examples of where a View might invoke a command include clicking a Save menu item, tapping a phone icon, or stretching an image. In these cases, the ViewModel will then invoke the business logic of saving outstanding changes, performing a phone call, or zooming into an image.
ReactiveCommand adds the concept of Input and Output generic types. The Input is often passed in by the View, and the Output is the result of executing the command. ReactiveCommand's are
IObservable<TOutput> which can be used like any other IObservable. For example, since the
IObservable<TOutput> you can
Subscribe() to it like any other observable, and add the output to a List on your view model. The
Unit type is a functional programming construct analogous to void and can be used in cases where you don't care about either the input and/or output value.
ReactiveCommand has full support for asynchronous logic and will block re-execution while executing.
ReactiveCommand guarantees the result of events are delivered to the provided
IScheduler (which defaults to the main thread scheduler). The executing logic thread safety is the user's responsibility but any result from the logic is guaranteed to arrive on the specified
ReactiveCommand is created using static factory methods which allows you to create command logic that executes either synchronously or asynchronously. The following are the different static factory methods:
CreateFromTask()- Executes a C# Task Parallel Library (TPL) Task. This allows use also of the C# async/await operators.
CreateFromObservable()- Execute the logic using an
Create()- Execute a synchronous Func or Action.
ReactiveCommand may or may not be executable in a given situation. For example, the command backing the Save menu item might be unavailable if there are no unsaved changes. We pass into the
IObservable<bool> of when the ReactiveCommand should be allowed to be executed. The
ReactiveCommand uses an IObservable eventing system to determine if execution should be allowed which differs from other frameworks where you might have the command continuous poll if execution is allowed. The ReactiveCommand approach has some performance advantages in that the value is cached between the can execute observable being fired. You commonly will create your can execute observable using the
WhenAnyValue functions provided by the ReactiveUI framework. Parameters, unlike in other frameworks, are typically not used in the canExecute conditions, instead, binding View properties to ViewModel properties and then using the WhenAnyValue() is far more common.
ReactiveCommand are fully integrated into the Reactive Extensions framework.
ReactiveCommand provides an IsExecuting property (also of type
IObservable<bool>) which tells you whether the command is currently executing. This is often useful if you want to trigger activity animations or you want to prevent other commands from executing while the command is executing.
ReactiveCommand can be connected to the View by either using XAML binding on supported platforms, or using the inbuilt ReactiveUI binding method
BindCommand. Use of BindCommand is preferred but not required where XAML binding is supported.
ReactiveCommand implements the
ICommand for UI framework compatibility and backwards compatibility only. It is recommended you don't use the
ICommand interface directly in your code.
ReactiveCommand is explicitly derived from the
ICommand interface to avoid users accidentally calling the non-reactive style methods. The
ICommand methods do not lend well to long-running and also asynchronous commands, such as those that perform I/O operations. The
ICommand also focuses on an imperative style of execution over the reactive style.
ReactiveCommand provides methods and observable properties that are the equivalent of the
Execute() provides an Observable which you can
Subscribe() to execute the logic of the
CanExecute is also exposed through a read-only property. Additionally
ReactiveCommand provides the
IsExecuting observable which is functionally not provided by the | <urn:uuid:524c90cb-fb8d-4d76-a043-7607b81d7a47> | 2.515625 | 894 | Documentation | Software Dev. | 17.782229 | 95,503,955 |
Scotland is often thought of as a land of tradition. Yet while many countries around the world have struggled to meet the increasing demand for clean, renewable energy, Scotland has lithely adapted. The European nation seems perfectly content to leave nuclear energy, which used to supply almost 100 percent of its electrical energy, behind in favor of wind energy.
Things have progressed so quickly over the past several decades, in fact, 25 percent of Europe's offshore wind resources are now located in Scotland. In valleys, on hills, and even atop mountains, massive wind turbines can be seen around the country, day or night, in constant rotation.
And they've got a lot to show for it. According to Pacific Standard, 2017 has been a record-breaking year for Scotland, in terms of renewable energy. So far, in the first six months of the year, the country has generated 57 percent of the country's total energy use, and around one million megawatt hours of electrical power.
In June alone, the country's wind turbines produced the equivalent of six day's worth of electrical energy for the entire country--enough to power 118 percent of Scottish homes. This is good news, considering Scotland's goal of reaching 100 percent renewable electricity by 2020.
According to Lang Banks, Director of WWF Scotland, Scotland's recent record-breaking energy output "...shows the importance of continuing increase capacity by building new wind farms." Lang told Power-Technology that, "As well as helping to power our homes and businesses, wind power supports thousands of jobs and continues to play an important role in Scotland’s efforts to address global climate change by avoiding millions of tonnes of carbon emissions.”
Yet, even with the incredible progress already being made this year, movement toward Scotland's 2020 goal has been tedious and difficult. According to Power-Technology, some policymakers in Scotland are concerned about the costs of building new wind farms, as well as their aesthetic effect on the landscape. Surprisingly, even some environmentalists are concerned about the expanding offshore wind farms, due to their potential effect on local bird populations, which includes species like gannets, puffins and kittiwakes.
Construction on four Scottish wind farms has already been delayed indefinitely due to legal battles between wind farm advocates and conversationalists, who believe that the turbines could have a devastating effect on colonies of migratory seabirds. Of the 1,000 wind turbines that were supposed to be in operation by the end of this year, only 63 have been raised, thus far.
The future of wind energy in Scotland remains uncertain, but one thing is clear: compromises will have to be made if Scotland is to reach its ambitious renewable energy goals. If offshore wind farms are not an option due to environmental issues, then onshore farms may need more support. The road to 100 percent renewable energy will certainly not be a straightforward one, but instead will likely be fraught with legal battles. Yet if the nation's recent record-breaking energy streak is anything to go on, progress is coming faster, in some ways, than many predicted, even if it is moving slower in others.
When it comes to plastic bags, one question persists: Are they recyclable, or not?
Tsumoru Shintake has invented a turbine that converts wave energy into clean electricity currently powering hotels.
This town in Long Island is using leftover shells from local restaurants to build a "living" barrier reef. | <urn:uuid:b0a6b12a-160f-4582-9018-3de50a4257c4> | 3.375 | 694 | News Article | Science & Tech. | 40.562153 | 95,503,958 |
Under an electron microscope they look like dandelions. In the journal Angewandte Chemie, Xiao-Fang Shen and Xiu-Ping Yan explain their nanoscopic bouquets: They consist of spread-out bundles of nanowires made of lead and the amino acid l-cysteine. The Chinese researchers have discovered a new, cost-effective method by which ordered nanostructures can be produced on a large scale, at room temperature, and under atmospheric pressure.
The properties of nanomaterials are not determined exclusively by their chemical composition; other characteristics such as structure and morphology, as well as the form, size, and spatial distribution of the individual particles, also play a role. It is equally important for the construction of future nanocomponents that nanomaterials can be produced with controlled “architecture”. For example, one-dimensional nanoobjects, known as nanowires, are needed for the (opto)electronics of the future and for the construction of superordinate structures.
Thanks to their specific structures and fascinating penchant for self-assembly, biomaterials make particularly interesting “molds” for the production of defined inorganic nanostructures. In particular, the amino acid cysteine easily forms coordination compounds with inorganic cations and metals.
The research team at Nankai University started with an aqueous solution of cysteine and lead acetate. At room temperature and under certain conditions, spindly bundles of nanowires form. These bundles spread out to form dandelion-like structures with a highly oriented morphology.
When heated under hydrothermal conditions, these structures decompose. Depending on the reaction conditions, hierarchical lead sulfide microstructures are formed with various attractive shapes, including spherical, needle-like, and different flower-like structures. Lead sulfide is an important semiconductor.
“Our new process enables the simple, controlled synthesis of nanowires and three-dimensional lead sulfide microstructures,” summarizes Yan. “In addition, we expect to gain new insights into the fundamental processes involved in mineralization, the transformation of bioorganic nano- and microstructures into inorganic structures. This process also occurs in living organisms, in which it plays an important role.”
Author: Xiu-Ping Yan, Nankai University, Tianjin (China), mailto:email@example.com
Title: Facile Shape-Controlled Synthesis of Well-Aligned Nanowire Architectures in Binary Aqueous Solution
Angewandte Chemie International Edition, doi: 10.1002/anie.200702451
Xiu-Ping Yan | Angewandte Chemie
O2 stable hydrogenases for applications
23.07.2018 | Max-Planck-Institut für Chemische Energiekonversion
Scientists uncover the role of a protein in production & survival of myelin-forming cells
19.07.2018 | Advanced Science Research Center, GC/CUNY
A new manufacturing technique uses a process similar to newspaper printing to form smoother and more flexible metals for making ultrafast electronic devices.
The low-cost process, developed by Purdue University researchers, combines tools already used in industry for manufacturing metals on a large scale, but uses...
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
23.07.2018 | Materials Sciences
23.07.2018 | Information Technology
23.07.2018 | Health and Medicine | <urn:uuid:9214607d-bdbe-42cd-9ca8-43fe376f93a9> | 3.515625 | 1,156 | Content Listing | Science & Tech. | 24.992789 | 95,503,986 |
Dutch ecologist Roxina Soler and her colleagues have discovered that subterranean and aboveground herbivorous insects can communicate with each other by using plants as telephones. Subterranean insects issue chemical warning signals via the leaves of the plant. This way, aboveground insects are alerted that the plant is already ‘occupied’.
Aboveground, leaf-eating insects prefer plants that have not yet been occupied by subterranean root-eating insects. Subterranean insects emit chemical signals via the leaves of the plant, which warn the aboveground insects about their presence. This messaging enables spatially-separated insects to avoid each other, so that they do not unintentionally compete for the same plant.
In recent years it has been discovered that different types of aboveground insects develop slowly if they feed on plants that also have subterranean residents and vice versa. It seems that a mechanism has developed via natural selection, which enables the subterranean and aboveground insects to detect each other. This avoids unnecessary competition.
This research was carried out at the Netherlands Institute for Ecology (NIOO-KNAW) by Roxina Soler, Jeffrey Harvey, Martijn Bezemer, Wim van der Putten and Louise Vet. The PhD project, in which this study was carried out, was funded by the Free Competition of NWO Earth and Life Sciences.
Sonja Knols | alfa
Colorectal cancer risk factors decrypted
13.07.2018 | Max-Planck-Institut für Stoffwechselforschung
Algae Have Land Genes
13.07.2018 | Julius-Maximilians-Universität Würzburg
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
13.07.2018 | Event News
13.07.2018 | Materials Sciences
13.07.2018 | Life Sciences | <urn:uuid:31133e8d-7238-4ccb-80ac-790cd27b99c6> | 3.75 | 922 | Content Listing | Science & Tech. | 38.24511 | 95,503,996 |
We have studied the compaction of vapor-deposited amorphous solid water by energetic ions at 40 K. The porosity was characterized by ultraviolet-visible spectroscopy, infrared spectroscopy, and methane adsorption/desorption. These three techniques provide different and complementary views of the structural changes in ice resulting from irradiation. We find that the decrease in internal surface area of the pores, signaled by infrared absorption by dangling bonds, precedes the decrease in the pore volume during irradiation. Our results imply that impacts from cosmic rays can cause compaction in the icy mantles of the interstellar grains, which can explain the absence of dangling bond features in the infrared spectrum of molecular clouds. © 2007 American Institute of Physics.
Mendeley saves you time finding and organizing research
Choose a citation style from the tabs below | <urn:uuid:128f223f-8179-4e08-85ec-d02cb6eb05de> | 2.71875 | 171 | Academic Writing | Science & Tech. | 17.227727 | 95,503,997 |
2. The combustion of butane (C4H10 with oxygen gas will yield carbon dioxide and water. Calculate the % yield of CO2 when 42 grams of butane are burned with 16.0 grams of oxygen and 10. grams of CO2 was formed.
25% 100% 32% 74% 64%
3. Balance the following equation (find what number coefficient X is): NH3 (g) + O2 (g) --> NO (g) + XH2O (g).
2 3 4 5 6
4. Hydrogen gas and oxygen gas can form water. What mass of water will form from excess oxygen and 24.0 g H2? (Assume a complete reaction)
107 216 24.0 48.0 96.0
5. There are two beakers sitting on a table. One contains 56.20 grams of water. The other contains hydrochloric acid (HCl). The number of atoms of hydrogen in the HCl equals the number of total atoms in the beaker full of water. How many grams of HCl are in the second beaker?
341.4 grams 142.4 g 938.1 g 53.29 g None of these
6. Hydrochloric acid reacts with calcium carbonate yielding calcium chloride, water, and carbon dioxide. How many moles of calcium carbonate would be necessary to react with 8 moles of HCl?
1 2 3 4 5
7. There are 2.34 moles of substance A3 combined with 2.77 moles of substance B. Assume that the reaction goes to completion. After the reaction is complete, AB is reacted with substance C2. The reaction creates CB and A. If C2 was in excess during the second reaction, then how many moles of CB were produced?
2.43 moles 3.82 moles 4.38 moles 7.02 moles None of these
8. What is the mass percent of oxygen in H2SO4 (sulfuric acid)?
0 1% 2.04% 32.70% 65.26%
9. Substance A combines with substance B to form Substance AB. B is a diatomic molecule. You are given 3.15 moles of B2. If A is in excess, how many moles of AB are produced?
1.20 2.30 3.25 5.60 6.30
10. What is the % mass of carbon in carbon dioxide?
44% 25% 27% 63% 50%
11. The formation of ammonia is shown by the following reaction: N2 (g) + 3H2 (g)--> 2NH3 (g). You are given 13.85 grams of nitrogen and 5.27 grams of hydrogen. If the experiment produced 3.297 grams of ammonia, then what is the percent yield?
25% 50% 35.80% 76.60% None of these
12. How many grams is 0.25 moles of table salt (NaCl?)
58.44 grams 14.61 grams 14.6 grams 58 grams 15 grams
13. How many moles in 20 g of water?
1.11 20 18 1.1 42
14. When aluminum reacts with sulfuric acid, the result is aluminum sulfate and hydrogen gas. How many moles of sulfuric acid (H2SO4) will react with 24 moles of aluminum?
12 14 16 18 20
15. When 2 moles of propane (C3H8, MW = 44 grams) is combusted with oxygen gas, how many grams of CO2 (MW: 44 grams) are produced?
88 44 3 132 264
| about us | contact us
tutorials index | organic
chemistry | practice tests | online
quizzes | reference tools
site copyright (c) 2002 to neopages.com | <urn:uuid:2b1e8c09-db00-48ee-b7b6-4647a5a7725d> | 3.875 | 811 | Content Listing | Science & Tech. | 102.495489 | 95,504,018 |
As obesity rates continue to rise in many parts of the world, Cait MacPhee explains how soft-matter physicists could help reverse the trend by crafting “functional” foods that promote feelings of fullness and satisfaction
The developed world is getting fatter. In the UK, the incidence of obesity has almost quadrupled in the last 25 years; within the (mostly wealthy) countries that make up the Organisation for Economic Co-operation and Development (OECD), the majority of the population is now either overweight or obese. The reasons for this collective weight gain are manifold, and although sedentary lifestyles and the ready availability of calorie-dense foodstuffs are obvious contributors, they don’t appear to be the whole story. When we eat, our bodies respond with an incredibly complex hormonal process, one that takes into account not just what’s on our plates that day, but also what we have eaten in the past, and how much of it. Unfortunately, the outcome of this response is that, essentially, we train our bodies to get fat – and it doesn’t seem to be easy to train them to become thin again.
As an example, consider the process we use to recognize when we have eaten enough. The sensations of satiety (recognizing that we are full) and satiation (recognizing that we don’t want to eat again yet) stem from external social cues (such as plate size and portion size) and mechanical cues (a full stomach), but also from the response of our metabolism. When our gut detects the presence of fatty acids, sugars, amino acids or the breakdown products of proteins, it releases several known “satiety” hormones. These hormones help make us feel “full”, but the way our body releases them and how our brain reacts to them is complex and not yet fully understood. Our gastrointestinal tract is a complex organ: for example, the taste receptors in our mouths – the ones that enable us to tell whether foods are sweet, salty, sour, bitter and savoury (umami) – are also present in our stomach, small intestine and colon. It is not just our mouths that “taste” our food.
Injecting any of the satiety hormones temporarily decreases calorie intake in both lean and overweight humans, but unfortunately, these hormones are rapidly turned over in the body and the effect does not last to a second meal. Moreover, repeated doses do not lead to weight loss because our complex interconnected hormonal response adjusts to the presence of additional hormones. Thus the satiety hormones themselves probably do not represent good candidates for therapeutics. So what are the alternative prospects for intervention?
One option is to use social cues to promote satiety by, for example, decreasing the portion sizes of packaged foods: unsurprisingly, we eat less when less is available. We could also make foodstuffs denser and chewier, since we eat less when we eat slowly and chew more. However, given our fast-paced lifestyle and the prevalence of food-on-the-go, this may not be a realistic choice. And while we’re being pragmatic, we should also recognize that processed foods aren’t going to disappear overnight.
An alternative option is to re-engineer our food. That may sound extreme, but in some sense, it has already been done: many modern processed foods have been developed in response to consumer desires for creamier, richer, tastier foods. The challenge this time is to create tasty foods that can also deliver triggers for the release of satiety hormones directly to those tissues where they will do most good. This is where soft-matter physics enters, with the development of so-called “functional” foods.
Beyond mere nutrition
Functional foods are foods that offer added physiological effects beyond “normal” nutritional value and taste. Examples include bread, milk and orange juice enriched with vitamins; yoghurt with added “probiotic” bacteria; eggs with increased omega-3 fatty acids; and meat products with added fibrous material to decrease fat content. Functional foods can also make life easier for people with allergies and other health conditions: lactose-free and gluten-free foods are increasingly seen on supermarket shelves. But replacing ingredients in foods with healthier alternatives – or, in the case of satiety-promoting ingredients, adding new ingredients to established recipes – is not always easy. Food formulations are complicated and have often been developed empirically over time, so that removing an ingredient or adding a new one can have unexpected outcomes.
The task of understanding the structures of foodstuffs and food formulations falls squarely within the realm of soft-matter physics: the study of complex fluids containing dispersed structures such as bubbles, colloids, emulsions and/or polymers. The size of these structures ranges from nanometres to microns, similar to the length scale that you can detect on your tongue or in your mouth as you chew. Ice cream, for example, contains air bubbles, emulsions, ice crystals as colloidal particles, and proteins as both polymer and amphiphile (a molecule that has both water-soluble and water-insoluble parts). Chocolate consists of cocoa particles, sugar crystals and protein polymers in a continuous phase of cocoa butter. Beer foam is stabilized by polymeric biomolecular degradation products. And to a soft-matter physicist, pasta is basically just an amorphous carbohydrate in a glassy phase. All of these food formulations are beleaguered with biological complexity, but they are tractable and offer many approaches for delivering new, functional ingredients to the correct part of the body.
One possible approach for delivering satiety-promoting hormones to the gut would be to use emulsions – droplets of one liquid (the “dispersed phase”) suspended in another (the “continuous phase”). Many different processed foods contain emulsions: salad dressings, for example, are oil droplets suspended in a water-rich phase, while butter and margarine are water droplets suspended in an oil-rich phase. The emulsion droplets can be stabilized by amphiphiles (emulsifiers) to prevent coalescence, or they can be suspended in “texture modifiers” that thicken or gel the continuous phase, preventing droplets colliding. As these systems consist of aqueous, oily and amphiphilic phases, they can also accommodate many different functional ingredients to promote satiety, potentially simultaneously. By combining and processing emulsions appropriately it is possible to create a range of textures, from pastes and gels to freely flowing liquids. Some can even be dried and added as a powdered ingredient. Importantly, emulsions can be created from a range of food-grade ingredients using relatively simple and energy-efficient processing methods. Emulsions do have some limitations, however, many of which are encountered during food preparation. High and low temperatures (such as those encountered when cooking, chilling or freezing food), vigorous mixing, and changes in pH can all cause the droplets in emulsions to become unstable. This creates problems for would-be developers of functional foods. If oil-in-water emulsions are destabilized, for example, an oil-rich phase can be formed in or on the foodstuff – an undesirable product behaviour known as “oiling out”. The stability of the emulsion droplets can be improved by coating them with a thin solid surface layer built up from charged polyelectrolytes such as carbohydrate polymers or proteins. This layer can be chosen so as to dissolve or become porous only under certain conditions of pH and/or salt, for targeted release of satiety factors at certain places in the gut.
The surface layer does not have to be thin and does not have to be formed from polymer layers: cellulose particles or even smaller emulsion droplets that are themselves stabilized with a surface layer of protein can pack around an emulsion droplet, forming what is known as a Pickering emulsion (figure 1). The use of such emulsions, however, depends on the food: emulsions of this size can be detected in the mouth, and in semi-liquid preparations such as yoghurt, they give an unpleasant gritty consistency.
A further example of emulsion technology is an emulsion droplet captured within an emulsion – a hierarchical structure known as a “multiple emulsion”. Examples might be oil droplets within a water droplet suspended in an oil continuous phase, or water droplets inside an oil droplet in a primarily aqueous formulation. Multiple emulsions are useful for “trapping” volatile ingredients, preventing them from diffusing out of the food by surrounding them with a medium through which they cannot pass. They are also useful for trapping ingredients that might otherwise taste bitter, by preventing their release in the mouth. Finally, multiple emulsions can protect fragile ingredients from the surrounding environment, preventing unwanted chemical reactions that may lead to food spoilage.
Although emulsions offer many opportunities for encapsulating and delivering functional ingredients, unfortunately the development of functional foods is a little more complicated than simply picking the right emulsion off the shelf. Our body responds differently to emulsion particles of different sizes and compositions. Some studies have shown that smaller emulsion droplets deliver both calories and satiety, while larger ones deliver the calories but with a muted satiating effect. The location where the emulsion is processed within the body also matters: if oily emulsions are unstable in the acidic environment of the stomach, the stomach becomes lined with fat, which seems to decrease satiety. But the breakdown products of fats are satiety-inducing factors themselves. Until we understand this complex interplay between the processing conditions that make emulsions larger or smaller, our enjoyment of the resulting foods in terms of taste and texture, their digestion in our gut, and the subsequent release of satiety hormones, we are trying to hit a moving target.
Proteins are also attractive ingredients for food structuring. Compared to fats, they have two important advantages: a lower calorie density and an increased intrinsic satiety. Simple changes in temperature or pH can cause proteins to form filamentous (transparent) or particulate (opaque) gels that can be used to give foods texture. As mentioned above, these texture-modifying gels can be used to prevent or slow the emulsion droplets coalescing, by thickening the surrounding medium. Alternatively, by controlling how proteins stick together through simple changes in temperature and/or pH it is possible to form protein particles that act similarly to emulsions. Like emulsions, these can be used to encapsulate and promote the slow release of satiety-promoting ingredients, while also giving foods a “creamy” texture without the addition of fats or oils.
Similar effects can be achieved with carbohydrate polymers such as starch, cellulose, chitosan, alginate and gums including guar gum and xanthan. Many of these are used to encapsulate bacteria as probiotics; however, careful processing is required to make these capsules resistant to the acid environment of the stomach, which could otherwise destroy the bacteria before they reach the intestine. Many of these polysaccharides are also used as thickening agents, and a number of them cannot be digested, so do not directly contribute to calorie content. Some of these “dietary fibres” are also intrinsically satiety-inducing, perhaps by adding bulk or increasing water content to foods and giving rise to a mechanical feeling of fullness, but possibly by triggering the release of satiety hormones following fermentation in the intestine.
Foods for the future
Re-engineering processed foods to have a lower energy density is, in theory, a relatively straightforward matter: all you need to do is replace high-calorie ingredients (such as fats) with low-energy-density alternatives (such as dietary fibre). However, doing so typically has an impact on consumer satisfaction, as both the taste and texture of the food are affected. Food physics offers the opportunity to get around this dilemma by creating new products that mimic the texture and taste of unhealthy but well-loved foods, with added components that, when released in a controlled fashion at specific sites within the body, improve our feeling of satisfaction. Clever food processing also offers the potential for decreasing the amount of salt and sugar in processed foods, at least where they are added for reasons other than taste or nutrition.
In an ideal world in which processed foods were eaten rarely or not at all, such solutions would not be necessary. However, in a world where 90% of Americans purchase convenience foods and more than 50% of the calorie intake in the UK comes from ultra-processed and energy-dense foods, such advances are clearly desirable. Perhaps clever physics may yet help us stem the developed world’s obesity crisis.
- Enjoy the rest of the November 2016 issue of Physics World in our digital magazine or via the Physics World app for any iOS or Android smartphone or tablet. Membership of the Institute of Physics required | <urn:uuid:7adf79e7-abac-448c-9c88-2019b38e9e16> | 2.875 | 2,696 | Truncated | Science & Tech. | 23.895234 | 95,504,039 |
"A large fraction of all the gas in the Universe has extremely cold temperatures of around minus 250 degrees Celsius, a mere 20 degrees above absolute zero," says Karl Menten, director at the Max Planck Institute for Radioastronomy (MPIfR) in Bonn, Germany, that built LABOCA. "Studying these cold clouds requires looking at the light they radiate in the submillimetre range, with very sophisticated detectors."
Astronomers use bolometers for this task, which are, in essence, thermometers. They detect incoming radiation by registering the resulting rise in temperature. More specifically, a bolometer detector consists of an extremely thin foil that absorbs the incoming light. Any change of the radiation's intensity results in a slight change in temperature of the foil, which can then be registered by sensitive electronic thermometers. To be able to measure such minute temperature fluctuations requires the bolometers to be cooled down to less than 0.3 degrees above absolute zero, that is below minus 272.85 degrees Celsius.
"Cooling to such low temperatures requires using liquid helium, which is no simple feat for an observatory located at 5100m altitude," says Carlos De Breuck, the APEX instrument scientist at ESO.
Nor is it simple to measure the weak temperature radiation of astronomical objects. Millimetre and submillimetre radiation opens a window into the enigmatic cold Universe, but the signals from space are heavily absorbed by water vapour in the Earth's atmosphere. "It is a bit as if you were trying to see stars during the day," explains Axel Weiss of the MPIfR and leader of the team that installed LABOCA on APEX.
This is why telescopes for this kind of astronomy must be built on high, dry sites, and why the 5100m high plateau at Chajnantor in the extremely dry Atacama Desert was chosen. Even under such optimal conditions the heat from Earth's atmosphere is still a hundred thousand times more intense than the tiny astronomical signals from distant galaxies. Very special software is required to filter such weak signals from the overwhelming disturbances.
LABOCA (LArge BOlometer Camera) and its associated software were developed by MPIfR. "Since so far there are no commercial applications for such instruments we have to develop them ourselves," explains Ernst Kreysa, from MPIfR and head of the group that built the new instrument.
A bolometer camera combines many tiny bolometer units into a matrix, much like the pixels are combined in a digital camera. LABOCA observes at the submillimetric wavelength of 0.87 mm, and consists of 295 channels, which are arranged in 9 concentric hexagons around a central channel. The angular resolution is 18.6 arcsec, and the total field of view is 11.4 arcmin, a remarkable size for instruments of this kind.
"The first astronomical observations with LABOCA have revealed its great potential. In particular, the large number of LABOCA's detectors is an enormous improvement over earlier instruments," says Giorgio Siringo from MPIfR and member of the LABOCA team. "LABOCA is the first camera that will allow us to map large areas on the sky with high sensitivity."
The Atacama Pathfinder Experiment (APEX) where LABOCA is installed is a new-technology 12-m telescope, based on an ALMA prototype antenna, and operating at the ALMA site. It has modified optics and an improved antenna surface accuracy, and is designed to take advantage of the excellent sky transparency working with wavelengths in the 0.2 to 1.4 mm range.
"APEX is located a mere 2 km from the centre of the future ALMA array. The new LABOCA camera will be very complementary to ALMA, as its very wide view will find thousands of galaxies which will be observed in great detail with ALMA," says De Breuck.
APEX is a collaboration between the Max Planck Institute for Radioastronomy, Onsala Space Observatory and ESO.
Henri Boffin | alfa
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:60373077-bfd1-4dd8-a62f-14ad6b710ca1> | 3.90625 | 1,487 | Content Listing | Science & Tech. | 38.617916 | 95,504,041 |
Start Your Free Trial
Log In · Join
On This Day
Start Your Free Trial
What are you looking for?
Click here to search
Browse popular topics:
Enhance your search results page with Britannica’s FREE Chrome extension.
Install now – FACTS matter.
Images and Videos
The Temelín Nuclear Power Plant, South Bohemia, Czech Republic, which went into full operation in 2003, using two Russian-designed…
Sequence of events in the fission of a uranium nucleus by a neutron.
Chain reaction in a nuclear reactor at a critical stateSlow neutrons strike…
The Angra nuclear power plant, using pressurized-water reactors, at Angra dos Reis, near Rio de Janeiro, Brazil.
Cherenkov radiation emitted by the core of the Reed Research Reactor located at Reed College in Portland, Oregon, U.S.
The basic components of a nuclear reactor.
The core of a pressurized-water nuclear reactor.
Nuclear fuel rods and control rods arranged by grid spacers into a fuel assembly for a pressurized-water reactor.
Installation of the dome of a containment structure at the Taishan nuclear power plant, Guangdong province, southern China,…
Basic power cycles in nuclear power plants(A) Single-loop cycle; as shown,…
Section of a pressurized-water reactor, showing inlets and outlets for water coolant passing through the core.
Cross section of a boiling-water reactor, showing the core, the steam separator, and the steam dryer.
Schematic diagram of a nuclear power plant using a pool-type sodium-cooled liquid-metal reactor.
Schematic diagram of a nuclear power plant using a Canada Deuterium Uranium (CANDU) reactor.
Dungeness B, a nuclear power plant using an advanced gas-cooled reactor, located at Dungeness Point, Kent, England.
A water-cooled research reactor, with graphite blocks serving as an internal reflector to moderate the reaction.
The nuclear-powered submarine USS
entering New York Harbor, 1958.
, commissioned in 1961, the first nuclear-powered aircraft carrier of the U.S. Navy.
The Soviet/Russian nuclear-powered icebreaker
, launched in 1957 and in service from 1959 to 1989.
Aerial view of Three Mile Island near Harrisburg, Pennsylvania.
Repairs under way at the Chernobyl nuclear power plant, Pryp'yat, Ukraine, October 1986.
Two of the damaged containment buildings at the Fukushima Daiichi nuclear power plant, northeastern Fukushima prefecture,…
A man is checked for radiation exposure after having been evacuated from the quarantine area around a nuclear power station…
A “closed loop” nuclear fuel cycle, showing the reprocessing of uranium-235 and plutonium from spent fuel for use in new…
Three uranium-enrichment processes.
Spent nuclear fuel rods stored underwater at the Bruce Power site near Tiverton, Ontario, Canada.
Containers of nuclear waste stored above ground at the Diablo Canyon Power Plant, San Luis Obispo county, California.
Cutaway diagram of a dry storage cask for spent nuclear fuel, showing fuel assemblies packed into a metal canister that is…
Scientists observing the world's first self-sustaining nuclear chain reaction, in the Chicago Pile No. 1, December 2, 1942.…
Cutaway drawing of the Zero-Energy Experimental Pile (ZEEP), which on September 5, 1945, became the first nuclear reactor…
The pressure vessel for the first commercial nuclear power plant in the United States being lowered into place at the Shippingport…
The Calder Hall nuclear power station, Cumbria, England, 1956.
The Civaux nuclear power plant, using pressurized-water reactors, near Poitiers, western France.
The Ikata nuclear power plant, employing pressurized-water reactors, located in Ehime prefecture, Shikoku, Japan.
The Tianwan nuclear power plant, using pressurized-water reactors, in Lianyungang, Jiangsu province, China.
Chernobyl disaster (03:46)
Overview of the Chernobyl disaster.
Chernobyl disaster; radiation: biological effects (03:02)
How the Chernobyl nuclear disaster of 1986 continued to affect survivors' health 30 years later.
Chernobyl disaster: visit to the site (02:58)
A visit to the site of the Chernobyl disaster.
You may also be interested in...
Media for: Fusion reactor
Media for: Nuclear fission
Media for: Nuclear power
Computers: Fact or Fiction?
Acoustics and Radio Technology: Fact or Fiction?
Where Did the Moon Come From?
5 Mysteries of Jupiter That Juno Might Solve
You have successfully emailed this.
Error when sending the email. Try again later.
On This Day
Nuclear reactor: Images and Videos
Back to Article
Email this page | <urn:uuid:7cb22021-a419-4914-a162-3ebad8c28d1d> | 3.625 | 1,045 | Truncated | Science & Tech. | 43.228825 | 95,504,049 |
“The rover discovered evidence for low temperature liquid water and environments that would be conducive for life,” said Scott M. McLennan, Professor of Geochemistry at Stony Brook University and a member of the team that published the paper (Steven Squyres of Cornell University headed the team and is the principal investigator for the science instruments carried by the rover). Dr. McLennan noted that this was the third area on Mars visited by the Mars rovers that has produced evidence of “habitable” ancient geological environments.
Opportunity was one of two exploration rovers that landed on Mars eight years ago for what was planned as a three-month mission. According to the NASA Jet Propulsion Laboratory, Opportunity reached Endeavour Crater last August after driving for three years from another Martian crater, Victoria.
Dr. McLennan said Opportunity found highly elevated levels of zinc in some of the rocks at the rim of the crater, suggesting that there was a hydrothermal system – warm water – running through the rocks at one time. In addition, veins of gypsum discovered at the crater were strong evidence that low temperature waters had at one time passed through those rocks.
“If we found this on Earth there would be no question that you could find evidence of life,” said Dr. McLennan, noting that the Rover sent back some “spectacular” photos of the gypsum veins.
The Mars Rover Opportunity has given Stony Brook faculty and graduate and undergraduate students the opportunity to collaborate for eight years on scientific study of Mars as part of the Stony Brook Mars rover group, Dr. McLennan said. While Opportunity and its sister Rover Spirit were scheduled to operate for three months, “Everyone felt they had the capability of lasting quite a bit longer, but nobody thought Opportunity would last this long.” NASA selected Dr. McLennan to participate in the Mars Exploration Rover (MER) Mission.
The mission consisted of two rovers that arrived on opposite sides of Mars in 2004. Dr. McLennan has investigated data on Martian rock and surface deposits to gain insight into the ancient climates of that planet and contribute to NASA's overarching strategy of Mars Exploration: "Follow the Water", the search for past life on Mars, understanding past climates and why the climate changed so drastically, and evaluating the planet for human exploration. Opportunity landed in Eagle Crater on Mars on Jan. 25, 2004, three weeks after its rover twin, Spirit, landed halfway around the planet. Spirit stopped communicating in March 2010.
Powered by solar panels, Opportunity went into “hibernation” on a sun facing slope at the crater’s rim during the Martian winter due to reduced sunlight. It is scheduled to come out of that hibernation by mid-2012 or earlier if wind cleans dust off its solar panels. According to NASA, researchers plan to drive Opportunity in search of clay minerals that a Mars orbiter's observations indicate lie on Endeavour's rim.
Scott M. McLennan | Newswise Science News
What happens when we heat the atomic lattice of a magnet all of a sudden?
18.07.2018 | Forschungsverbund Berlin
Subaru Telescope helps pinpoint origin of ultra-high energy neutrino
16.07.2018 | National Institutes of Natural Sciences
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
19.07.2018 | Earth Sciences
19.07.2018 | Power and Electrical Engineering
19.07.2018 | Materials Sciences | <urn:uuid:bdf652f9-80b0-422f-8987-8cad868f9455> | 3.46875 | 1,266 | Content Listing | Science & Tech. | 41.67664 | 95,504,052 |
Long-term monitoring of surface water quality has shown increasing concentrations of colored dissolved organic matter (CDOM) across large parts of the northern latitudes. This has increased purification costs for domestic water works. Appropriate abatement actions require better knowledge of the governing factors for the increase, and this has motivated a growing scientific interest in understanding the factors and mechanisms promoting the CDOM increase. A proposed water color model for an important raw water source for Oslo, Norway, is based on the precipitation's amount and mobile ion concentration. The model explained more than 93% of the temporal variation in CDOM between 1983 and 2008. The model structure was also tested on three adjacent raw water sources and was found to explain 75-82% of the CDOM development throughout the same period. The long-term trend of increasing CDOM was closely related to the decline in sulfate and chloride concentrations in precipitation. Furthermore, interannual fluctuations in CDOM were explained by variation in predominant water flow paths, depending on amounts and intensity of precipitation, both of which are predicted to increase in several parts of the northern latitudes according to climate change scenarios.
Mendeley saves you time finding and organizing research
Choose a citation style from the tabs below | <urn:uuid:757641fc-9830-46fb-8b61-2d17cee0d18d> | 2.96875 | 248 | Academic Writing | Science & Tech. | 18.972885 | 95,504,054 |
This article was originally posted on the Union of Concerned Scientists blog. Click here to read the original.
1 September 2015 | You already know that rapid loss of Arctic glaciers and ice sheets is helping to speed up the sea level rise that is causing worsening coastal flooding in communities from Maine to Miami. And you probably even know that warming in the Arctic seems to be driving changes to the weather patterns elsewhere on the globe. (If both these things have passed you by, you need to read the recent blog by my colleague Brenda Ekwurzel.)
If you’ve been following the media build-up to President Obama’s trip to Alaska, you’ve also been getting the message that “what happens in the Arctic doesn’t stay in the Arctic.”
The day before the president arrived in Anchorage, I attended a climate science briefing organized by the Alaska Ocean Observing System (AOOS) and WWF that really brought the scientific basis for that message home to me.
The briefing was designed as a “speed-dating event” to introduce some of Alaska’s top climate impacts scientists to journalists who are in Anchorage to cover the President’s visit. Ten scientists were given just five minutes each to get across the essence of what often involved years or even decades of research and why it matters to Americans. Here are some the things we learned.
1) Alaskan wildfires are speeding up the release of carbon to the atmosphere
Boreal forest represents about one third of the world’s forest and contains about one third of all terrestrial carbon. One third of that boreal forest is in North America. Half of Alaska—an area four times the size of Washington State—is covered by boreal forest.
Just as in the rest of the western United States, warming temperatures are driving an increase in large wildfires in Alaska. In the whole of the forty-year period from 1950-1989 wildfires burned 27 million acres in Alaska. In contrast, in just the last 5 years a staggering 37 million acres have burned. 2015 was the worst fire season ever and smoke from Alaska contributed to haze as far away as Ohio and Long Island. Scott Rupp from the University of Alaska says that every bad fires season like this can wipe out decades of accumulated carbon in the forests and send it back into the atmosphere to contribute to global warming.
According to a new report from the National Research Council of the National Academies, large wildfires are now spreading into some permafrost regions, driven by drier conditions. This is something that is unprecedented in the last 10,000 years, and the most severe fires can burn off the surface vegetation, speeding the thawing of the permafrost below.
2) Thawing of the permafrost is going to make things even worse
The Arctic permafrost contains almost 1500 billion tons of carbon, almost twice what is already in the atmosphere.
In Alaska, according to Vladimir Romanovsky of the University of Alaska, permafrost has warmed substantially since the mid-1980s, even down to 50 meters deep. At some sites on the North Slope, warming has been as much as 6°C at the surface. Thawing permafrost has severe local impacts including damage to infrastructure such as homes, roads and pipelines, and accelerated erosion along the coast.
But the real global danger from melting permafrost is the release of vast quantities of carbon to the atmosphere. Scientists Max Holmes, Susan Natali, and colleagues fromWoods Hole Research Center note that “carbon emissions from thawing permafrost accelerate global warming, so the potential exists for a catastrophic, self-reinforcing cycle of warming and thawing permafrost.” 130-160 billion tons of carbon could be released before 2100—roughly equivalent to 100 times current annual U.S. emissions of carbon from fossil fuels and cement production.
3) Finding smoked salmon for your bagel may get a whole lot harder
Salmon provide a cultural touchstone for all Alaskans and they form the basis for an enormously economically important fishery. 95% of US wild salmon comes from Alaska. However, salmon are highly sensitive to river temperatures, and warmer temperatures are threatening the state’s fisheries. Stream temperatures of 20°C are lethal for salmon and these levels have been exceeded in recent years on the Kenai Peninsula. Aside from the direct impacts of temperature, parasites such asIchthyophonus can thrive in warmer temperatures, as was seen in recent years when Yukon River temperatures rose significantly above normal and an epidemic broke out in the King salmon population.
4) Changes in the Bering Sea fishery are going to affect your shopping basket
Alaska accounts for more than 50% of the total U.S. fish catch, with the bulk of this being pollock, cod, and flatfish. Alaskan fish populations clearly respond to temperature fluctuations, including climate change and cyclical variations such as El Nino. Because of warming ocean temperatures, cold-water species are being pushed northwards and more southerly species such as albacore tuna and ocean sunfish are being seen more frequently in Alaskan waters.
Recent research led by Gordon Kruse at the University of Alaska has demonstrated variations in predation of different age classes of pollock in response to warmer temperatures, the net effect being higher juvenile mortality and therefore slower population growth. There are numerous other impacts on fisheries too. Snow crab catch is correlated with sea ice extent and red king crab juvenile mortality is also affected by the condition of sea ice. In the absence of sea ice, the phytoplankton blooms occur too late for the juvenile crabs that depend on them for food in the first few days of their development.
5) Ocean acidification too? Really? Can’t fisheries get a break?
Ocean acidification is climate change’s evil twin. It doesn’t occur as a result of climate change, but is a direct result of increasing levels of carbon dioxide in the atmosphere.
When CO2 dissolves in seawater it lowers the pH of the water and this acidification has the capacity to dissolve or degrade the calcium carbonate shells of species such as crustaceans, shellfish, corals, and calcifying phytoplankton.
Many Alaskan waters are particularly vulnerable to ocean acidification because of other factors that contribute, including freshwater input from glaciers and rivers, the capacity of cold waters to absorb more carbon dioxide, and upwelling from carbon dioxide rich deep waters. New research by scientists from NOAA, the University of Alaska, and the Woods Hole Oceanographic Research Institute predicts that ocean acidification will overwhelm the ability of marine calcifiers to build and maintain their shells within a decade in some Alaska waters. The threshold could be reached by 2025 in the Beaufort Sea, 2027 in the Chukchi Sea and 2044 for the Bering Sea, threatening the red king crab and snow crab fisheries among others.
6) The drying of Alaskan lakes might affect the birds you see in your own backyard
A warming and drying trend in Alaska is causing lakes to lose water and shrink. In fact Alaska is now losing 0.8% of its wetland area annually.
A recent study of 123 lakes in the state has shown that lake size is the best predictor of species richness. As lakes shrink, so too will the diversity of species they support. Birds that spend the summer in Alaska and breed there, and then spread out throughout the United States and beyond via a series of major migration flyways in the spring and autumn. Negative impacts of climate change on breeding success in Alaska will have ramifications for migratory birds including ducks, shorebirds, loons, and terns across the United States and probably in your local parks and wetlands. | <urn:uuid:fef4e6d4-815d-4acc-885d-ac89e3a7fc94> | 3.078125 | 1,607 | Listicle | Science & Tech. | 38.834792 | 95,504,076 |
Membranes and Electricity
Credit for the accidental discovery that an applied voltage makes muscle contract is given to Luigi Galvani (ca. 1760). Galvani found that two pieces of different metal wires touching a nerve in the leg of a freshly skinned frog caused the muscles to contract, provided that the other ends of the metal wires were in contact. Subsequently, Waller (ca. 1887) discovered that electrical currents were generated during each heartbeat and that they could be detected at the body surface. The string galvanometer was designed by Einthoven in 1913, and this instrument allowed him to record the electrocardiogram (ECG) on a routine basis. The rapidly developing science of electrocardiography then aided the physician in detecting and diagnosing various heart diseases.
KeywordsAlternate Current Myotonic Dystrophy Squid Giant Axon Membrane Resistivity Black Lipid Membrane
Unable to display preview. Download preview PDF. | <urn:uuid:9dc11f3c-6c72-49fd-89b5-5f34fc52bdc5> | 3.046875 | 198 | Truncated | Science & Tech. | 27.733333 | 95,504,111 |
Using genetically engineered mice, researchers with the University of Minnesota Medical School's Lillehei Heart Institute were able to identify a protein, Nkx2-5, which activates a certain gene, and in turn, determines the fate of a group of cells in a developing embryo.
"If we can understand the mechanism, or how certain stem cells choose a particular path, we can alter it to prevent or treat disease," said Daniel Garry, M.D., Ph.D., lead researcher, executive director of the institute, and chief of the cardiovascular division in the Department of Medicine. "This gene discovery provides the key to unlocking the secret of how blood vessels grow."
Researchers knew that certain precursor cells, or progenitor cells, become the three types of cells that make up the cardiovascular system: smooth muscle, endothelial (blood vessel), and cardiac muscle. What they didn't know, until now, is how those progenitor cells end up as one type or another. Garry likened the team's discovery to finding the recipe of how certain cells become blood vessels.
By understanding how the cells develop, Garry said they will be able to study how they might modify the gene to create a desired response.
"Next we are looking at how we could over-express the gene or knock it down," he said.
For example, in the case of heart disease or heart failure, they may be able to "turn on" the gene to make it create new, healthy blood vessels. Or, in the case of cancer, they could turn off the gene to limit blood supply to a tumor, causing it to shrink.
Sara Martin | EurekAlert!
Colorectal cancer risk factors decrypted
13.07.2018 | Max-Planck-Institut für Stoffwechselforschung
Algae Have Land Genes
13.07.2018 | Julius-Maximilians-Universität Würzburg
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
13.07.2018 | Event News
13.07.2018 | Materials Sciences
13.07.2018 | Life Sciences | <urn:uuid:8e59273c-a68c-4369-a892-7d7db5f44fea> | 3.328125 | 980 | Content Listing | Science & Tech. | 44.974858 | 95,504,116 |
Scattering arises from inhomogeneities within the medium in which an electromagnetic wave is propagating. This paper deals with both the theory of scattering and its applications as a means of exploring the temporal and spatial characteristics of media on a microscopic scale. The theoretical discussion of scattering demonstrates the existence of scattering and its induction by dielectric variations throughout a medium. It also develops a correlation function containing the microscopic information that determines the nature of the scattered light and extends the development from a time independent function to a time dependent one. This theory is then applied to the experimental determination of the size of microscopic particles. An experimental method for collecting the necessary data is presented and several methods of analysis are discussed. This apparatus used in conducting the experiments reported on in this paper is also presented along with the results of a study of the performance of this apparatus and the experimental errors inherent in it. Finally, scattering from samples of distilled water, tap water and suspended sediment was measured and it was found that the distilled water contained scatterers 1.55 and 2.5 micrometer in diameter, the tap water contained scatterers 1.33 and 0.044 micrometer in diameter. The existence of diffractive effects is also shown for particles larger that a wavelength in size. | <urn:uuid:7adcace9-a9f3-41b7-900d-d3f9501d72f9> | 3.4375 | 253 | Academic Writing | Science & Tech. | 24.208054 | 95,504,157 |
Recent drought conditions in the North Pacific Ocean near Hawaii have caused a decrease in the strength of the carbon dioxide sink, according to a study published this week in the journal Nature. A team funded by the National Science Foundation (NSF) and led by scientists Dave Karl and Roger Lukas of the School of Ocean and Earth Science and Technology (SOEST) at the University of Hawaii used 15 years of time-series measurements to compare the precipitation, salinity and carbon dioxide (CO2) concentrations at Station ALOHA, located in the Pacific Ocean approximately 100 kilometers north of Oahu.
The study shows that a decrease in the tendency of the ocean to take up CO2 is due to an increase in the waters salinity, which is a direct result of the drought seen in much of the North Pacific Ocean over the past five years.
"Our study can be considered an oceanic analogue of the long standing atmospheric measurement program at the Mauna Loa Observatory," says Karl. "The results from this study were unexpected; we didnt realize how much difference salinity can make when modeling the carbon cycle."
According to John Dore, a SOEST researcher and lead author of the study, rainfall patterns and ocean CO2 are inexorably linked. "We all recognize the impacts of drought on land, but its effects on the biogeochemistry of the ocean have tended to go unnoticed," says Dore.
The Hawaii Ocean Time-series (HOT) program is an ongoing field study designed to determine temporal variability in physical, chemical and biological processes in the North Pacific Subtropical Gyre (NPSG), one of Earths largest habitats. The program began in October 1988 with the establishment of the benchmark sampling site, Station ALOHA, at 22o45N, 158oW. Nearly every month for the past 15 years, a team of interdisciplinary scientists with common research objectives have been making shipboard measurements, conducting experiments and testing a broad range of ecological hypotheses.
"This extended period of time-series measurements is very rare," says Lukas. "Along with a sister station in Bermuda, Station ALOHA has the longest records of comprehensive biogeochemical and physical measurements anywhere in the world."
The data have already revealed unexpected variability in habitat changes and in the response of the organisms living there. The present study is but one important example. "These interesting results are another example that shows the importance of longterm observations to ocean research," says James Yoder, director of NSFs division of ocean sciences, which funded the research. "Ocean observatories of the future will provide the capability to tease out important signals that are missed during the comparatively short duration of oceanographic expeditions."
Scientists involved in the HOT project have recently received new funding (with other colleagues) from NSF to establish an autonomous ocean observatory at Station ALOHA, reusing an abandoned fiber optic telephone cable to extend the Internet from their offices to the seafloor three miles below the ocean surface. From there, the cable travels upward into the surface layer, providing the capability for real-time observations of ocean processes. "With this observatory we will move much of the sampling from the ship to our desktops," says Lukas. "But, there will always be a need for us to go to sea, both to maintain the observatory, and to make measurements that require water sampling."
During this next five-year observation period, the measurement program will move toward more autonomous detection of ocean characteristics by connecting instrumented moorings to the ALOHA observatory and using autonomous underwater vehicles and gliders to provide spatial context around the site.
The research was also funded by the State of Hawaii.
Global study of world's beaches shows threat to protected areas
19.07.2018 | NASA/Goddard Space Flight Center
NSF-supported researchers to present new results on hurricanes and other extreme events
19.07.2018 | National Science Foundation
A new manufacturing technique uses a process similar to newspaper printing to form smoother and more flexible metals for making ultrafast electronic devices.
The low-cost process, developed by Purdue University researchers, combines tools already used in industry for manufacturing metals on a large scale, but uses...
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
20.07.2018 | Power and Electrical Engineering
20.07.2018 | Information Technology
20.07.2018 | Materials Sciences | <urn:uuid:f8d0cea9-f73c-4aee-9921-8f8c08891ff9> | 3.203125 | 1,322 | Content Listing | Science & Tech. | 32.266236 | 95,504,192 |
The research is the first comprehensive study of its kind to examine how the public perceives, uses, and values weather forecasts. Funded by the National Science Foundation, NCAR's sponsor, and the National Oceanic and Atmospheric Administration, the study appears in the June issue of the Bulletin of the American Meteorological Society.
U.S. adults obtain an estimated 300 billion forecasts each year, says NCAR scientist and lead author Jeffrey Lazo. The study also reveals that most people are generally satisfied with weather forecasts and have fairly high confidence in forecasts with a lead time of one to two days.
"Weather forecasts equate to an enormous volume and multiplicity of information, when you account for the array of forecast providers, communication channels, and the size and diversity of the U.S. population," Lazo says.
Understanding how individuals use day-to-day weather information can help direct the development of more relevant and valuable weather forecasts and warnings by providers like the National Weather Service, he adds.
Gaining a better understanding of people's attitudes and behaviors toward forecasts also provides valuable information to forecasters and emergency managers.
"Better communication strategies can be developed for hazardous weather like hurricanes, winter storms, and floods," Lazo says. "Improved understanding will also help forecasters to communicate forecast uncertainty more effectively."
More than three forecasts a day
The Internet-based survey, conducted in November 2006, collected information about respondents' weather-related activities and experiences, as well as basic demographic information. Of the 1,520 individuals surveyed, 1,465 (96 percent) said they used weather forecasts.
Of those 1,465, 87.1 percent reported getting a forecast at least once a day on average, while 9.2 percent reported doing so once a day or less on average.
Although the number of forecasts a person obtains varies significantly from day to day, depending on factors like weather events and planned activities, the researchers found that on average survey participants received forecasts 3.8 times a day. These findings, when extrapolated to the total U.S. adult population of 226 million, indicate that Americans receive a yearly total of about 300 billion forecasts.
Valuing a forecast
The authors cautioned that it is difficult to put a dollar figure on the value of forecasts. However, the researchers asked respondents what they believed forecasts to be worth, presenting them with hypothetical amounts that they were currently paying in taxes and asking if they felt that value was correct, worth more, or worth less than the amount indicated.
Respondents indicated that, on a per-household basis, they would place an average value of about 10.5 cents on every forecast obtained. This equates to an annual value of $31.5 billion. In comparison, the cost of providing forecasts by government agencies and private companies is $5.1 billion, according to the paper.
"Our estimates indicate that Americans are getting a good deal on weather forecasts," says Lazo. "While it's hard to precisely estimate the value of the forecasts, it is clear that there is a significant difference between the cost of forecasts and the value that people place on them."
Fascination with the weather
Coauthor Julie Demuth, an NCAR associate scientist, says the study also reveals people's curiosity about the weather, with 85 percent of respondents saying that more than half the time they obtain forecasts simply to know what the weather will be like.
"This tells us that people generally have a high level of interest in weather forecasts, regardless of whether they are using this information directly for planning and decision making," says Demuth.
Many people use forecasts for planning specific activities, such as vacations, and routine daily activities, such as deciding what to wear and how to get to work or school. The peak periods for accessing forecasts are the early morning, early evening, and late evening, says Demuth.
The most common source for forecast information is local television stations, with individuals obtaining forecasts 33.7 times per month on average. Cable television and radio are the next most popular sources. Web pages and newspapers were less common sources overall, but both are a daily or more frequent source of forecasts for 27 percent of respondents.
"We should be doing this type of survey every two to three years so we can see what changes are happening, particularly in how people are using technology like mobile phones and the Internet to receive forecasts," says Lazo.
The University Corporation for Atmospheric Research manages the National Center for Atmospheric Research under sponsorship by the National Science Foundation. Any opinions, findings and conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the views of the National Science Foundation.
For reporters only:
To request a copy of the paper, send your name, organization, and phone number to David Hosansky at email@example.com, Rachael Drummond at firstname.lastname@example.org, or Stephanie Kenitzer at email@example.com.Title:
Rachael Drummond | Newswise Science News
Global study of world's beaches shows threat to protected areas
19.07.2018 | NASA/Goddard Space Flight Center
NSF-supported researchers to present new results on hurricanes and other extreme events
19.07.2018 | National Science Foundation
A new manufacturing technique uses a process similar to newspaper printing to form smoother and more flexible metals for making ultrafast electronic devices.
The low-cost process, developed by Purdue University researchers, combines tools already used in industry for manufacturing metals on a large scale, but uses...
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
20.07.2018 | Power and Electrical Engineering
20.07.2018 | Information Technology
20.07.2018 | Materials Sciences | <urn:uuid:07f49f81-2cfc-443d-bbd6-5a22fc058286> | 3.125 | 1,607 | Content Listing | Science & Tech. | 35.8065 | 95,504,208 |
On the northernmost tip of America’s northernmost state is the city of Utqiaġvik, Alaska. Hans Thewissen, a Dutch-born whale scientist who lives in Ohio, has been making the journey up here for more than a decade—at first once a year, now multiple times a year, always to coincide with local whale hunts. Utqiaġvik is one of the only places in America where one can legally procure a piece of fresh whale brain or eyeball or ear to study.
Whales are strictly protected under U.S. law and by the International Whaling Commission. They can of course be observed from afar, but that is not much use to Thewissen, who is interested in the finer points of whale anatomy. Dead whales wash up on the land sometimes, but they are usually rotting by the time scientists get to them. “This is really the only place,” says Thewissen. Utqiaġvik, formerly known as Barrow, is the largest of 11 communities where Alaska Natives are allowed to hunt whales for subsistence, as their ancestors have done for millennia. (Thewissen himself is not allowed on the hunts.)
These trips to the Arctic have made possible a series of uniquely intimate studies of bowhead whales—stout, blue-black creatures that grow up to 100 tons. Thewissen has peered inside the mouths of unborn whales, which grow and then reabsorb teeth before they develop the baleen that adult bowheads use to feed on krill. He’s sawed open whale skulls to trace nerve cells from the inside of the nose to the brain—proving that bowhead whales can indeed smell. He’s investigated mysterious whiskers that grow around the blow hole. All of these studies have required working closely with the Iñupiat people native to the area; some were directly inspired by conversations with whaling captains.
Utqiaġvik has long attracted adventurers and scientists, thanks to its location at the very north of the United States. Thewissen’s work fits into decades of research that draws on indigenous knowledge about the Arctic. This whale research is now an example of the productive collaboration between outside scientists and the Iñupiat, but that wasn’t always the case.
* * *
“I’ve been whaling all my life,” says Arnold Brower Jr., the executive director of the Alaska Eskimo Whaling Commission. The organization is made up of captains and crew from the 11 whaling communities. As young boy, Brower was out on the ice, watching and learning as grown-ups cut up whales to divide among families. As a young man, he was in the boats hunting whales. He’s almost 70 years old and still a whaling captain.
In 1977, the International Whaling Commission set a quota of zero for bowhead-whale hunting, dealing a significant blow to Alaska Natives who rely on whaling for subsistence. Brower recalls meeting with the United States’ delegate to the IWC at the time. The quota came out of concerns of low bowhead-whale populations based on a U.S. government survey. The number seemed far too low based on the experience of the whaling captains.
The captains formed the Alaska Eskimo Whaling Commission, and they eventually decided to conduct their own bowhead census to increase the quota. In 1982, the commission turned over the census to the local government of North Slope Borough, which encompasses Utqiaġvik. The borough hired its own scientists, who determined the federal-government census had been undercounting bowhead whales. The problem, as later recounted by Thomas Albert, one of those North Slope Borough scientists, was that the conventional scientific wisdom was wrong. Scientists thought that bowhead whales were “afraid” of ice and only swam in open water. In fact, those whales were swimming under ice, out of view from the previous observers.
It wasn’t easy at first for researchers and the Iñupiat hunters to work together. Albert recalled that the events from 1977 made the locals suspicious. “Some were reluctant to share their knowledge with scientists for fear that their bowhead information would be used against them by the federal government, the IWC, or both,” he wrote. Brower remembers it too. “At first, it didn’t seem like they should be there,” he says of the scientists. “It seemed bothersome when we’re trying to get our nutritional needs met.”
Over time though, thanks to personal relationships that developed between scientists and some of the Iñupiat, things got better. “Now studying the number of whales and having a census has become an important element in our quota,” Brower says. The North Slope Borough’s department of wildlife management still runs the bowhead-whale census. Hans Thewissen first got in touch with the borough over a decade ago because he was interested how whales develop in the womb. (Curiously, they grow and then lose traits that link them to land, like teeth and legs.) Utqiaġvik was one of the few places where he could find them.
* * *
Bowhead whale hunts take place twice a year in Utqiaġvik, in the spring and in the fall.
The spring hunt has traditionally been the more important one. Around mid-May, the whaling crews set out on snowmobiles for the edge of the sea ice. They set up camp for days or even weeks, waiting for migrating whales to appear.
Crews still use a traditional seal-skin boat called a umiaq in the spring. (The fall hunt uses motorized boats because there is no sea ice. As it’s gotten warmer in the Arctic and there’s been less ice in the spring, the fall hunt has become increasingly important.) Building a umiaq can take a couple years—between collecting driftwood, acquiring seal skins, and hunting caribou big enough that their sinew can be used to sew the skins together. Hunting and fishing to provision the whaling camps is another year-round endeavor.
“We don’t have our certifications and credentials like scientists,” says Harry Brower Jr., mayor of the North Slope Borough that includes Utqiaġvik and a whaling captain himself. But to even prepare to hunt whales is to be intimately familiar with the seasonal cycles of the Arctic.
Harry is also Arnold’s cousin. Their grandfather, Charles Brower, was a Yankee who came up to Utqiaġvik as a commercial whaler, married in the local community, and had 14 children. There are a lot of Browers in Utqiaġvik.
It’s about more than simple survival, says Harry: “We’re very spiritual and religious people in the North Slope. We know these resources are God-given resources.” When a whale appears near the ice close enough to be taken, the Iñupiat speak of the whale giving itself to a captain worthy of it.
(Anti-whaling activists, of course, don't see it this way, which has led to continued cultural clashes. When a 16-year-old boy caught a whale this spring—an enviable feat in his community—he became deluged with threats on Facebook after an activist posted a rant calling the teenager's actions murder.)
To capture a whale, the hunters first use a darting gun. If the darting gun does not kill the whale right away, they use another shoulder-mounted gun to hasten its death. The whale is then pulled onto the ice and butchered. Portions are set aside for the captain, crew, and others that helped butcher the whale.
Back in town, the organs are boiled at the captain’s house, where hundreds of townspeople might come to take part in the feast. The rest is stored in ice cellars carved out of the permafrost. It’s at this point that Thewissen gets his samples, too. “They know me standing out there,” he says. “There’s the ear guy again.”
During one of his visits, Thewissen heard the captains talking about the bowhead’s sense of smell. Scientists didn’t think that the whales could smell. After all, why would whales living in the water need to sense things in the air? But the Iñupiat knew that smoke from a campfire, for example, would drive whales far from the shore. On their suggestion, Thewissen dissected the head of the bowhead whale, only to find a nerve from the whale's nostril leading to an olfactory bulb in the brain.
In another study, he was puzzled about the buoyancy of baby whales. Young bowhead whales have a rich diet of milk, and they balloon into fat little babies. Once they’re weaned, they go into a period of relative starvation as their baleen slowly grows in. And they lose a lot of their buoyant fat. So how come a fat 1-year-old whale and and skinny 5-year-old whale both stay buoyant in the water?
Thewissen suspected it had something to do with the bones, but he couldn’t find any discernible pattern in his bone samples. Then one hunter suggested looking at the ribs. He said his father would use the ribs of 1-year-old bowhead whales—only 1-year-olds—to weigh down nets. So Thewissen looked at the ribs, which were indeed thick and heavy in one-year-old whales. Over a period of five years, he observed, the ribs would lose as much as 40 percent of their mass. It clicked: To compensate for losing fat, young whales lose bone mass in their ribs.
Craig George, a biologist with the North Slope Borough’s department of wildlife, helps conduct the bowhead census, and also does research on the whales with Thewissen. “It’s a win-win deal,” he says. Other research groups from as far away as Australia have also established collaborations in the North Slope to study whales. It’s not just whales either. Research into other Arctic species such as seals and migratory birds and caribou have also drawn heavily on local knowledge.
Things are changing in Utqiaġvik, of course. The ice has been getting thinner, as climate change has brought warm temperatures to the Arctic. Some of the younger generation isn't as keen on learning how to hunt whales. Harry Brower Jr. lamented this in a way that will be familiar to any parent: “Sometimes they aren’t active, just sit around watching TV or playing iPhones or iPads or computer games that take away time from learning their skills.”
At least some of the traditional knowledge is, if only in bits and pieces, being laid down in the written scientific record.
We want to hear what you think. Submit a letter to the editor or write to email@example.com. | <urn:uuid:cb888fba-5cd5-4b57-b3fa-94ed55b0f724> | 3.046875 | 2,366 | News Article | Science & Tech. | 57.30688 | 95,504,213 |
In this post we will discuss about what is Windows Presentation Foundation (WPF) in Asp.Net
Introduction to Windows Presentation Foundation:
Windows Presentation Foundation (WPF) is a next-generation presentation system for building Windows client applications with visually stunning user experiences. With WPF, you can create a wide range of both standalone and browser-hosted applications.
WPF extends the core with a comprehensive set of application-development features that include Extensible Application Markup Language (XAML), controls, data binding, layout, 2-D and 3-D graphics, animation, styles, templates, documents, media, text, and typography.
Programming with WPF:
WPF exists as a subset of .NET Framework types that are for the most part located in the System. Windows namespace.like ASP.NET and Windows Forms, the fundamental WPF programming experience should be familiar; you instantiate classes, set properties, call methods, and handle events, all using your favorite .NET Framework programming language, such as C#.Net
or Visual Basic.
WPF includes additional programming constructs that enhance properties and events: dependency properties and routed events.
WPF offers additional programming enhancements for Windows client application development.like the ability to develop an application using both markup and code-behind.You generally use Extensible Application Markup Language (XAML) markup to implement the appearance of an application while using managed programming languages (code-behind) to implement its behavior. This separation of appearance and behavior has the following benefits:
1- Development and maintenance costs are reduced.
2- Development is more efficient because designers can implement an application’s appearance simultaneously with developers who are implementing the application’s behavior.
3- Multiple design tools can be used to implement and share XAML markup, to target the requirements of the application development contributors; Microsoft Expression Blend provides an experience that suits designers, while Visual Studio 2010 targets developers.
4- Globalization and localization for WPF applications is greatly simplified.
Similar SharePoint 2013 Tutorials | <urn:uuid:cf53c86e-155b-4c68-a955-b5ba6901abeb> | 2.828125 | 426 | Truncated | Software Dev. | 19.340709 | 95,504,229 |
SolACES, the solar spectrometer developed by Fraunhofer IPM and installed on the ISS, supplied unique measurement data on solar activity for nine years. As the SOLAR research mission has come to an end, the successful experiment was ceremoniously deactivated on 15 February 2017 at the B.USOC control centre in Brussels.
The SolACES solar spectrometer flew to the International Space Station in February 2008 as part of the SOLAR research mission. Its planned lifetime was one and a half years. Yet SolACES reliably supplied data on the sun’s extreme ultraviolet (EUV) spectrum for nine years. Together with other measurement data, the SolACES data today forms the basis for modern climate models.
The SOLAR research mission successfully supplied measurement data on the solar spectrum for a period of nine years – with the help of Fraunhofer IPM’s »SolACES« EUV spectrometer.
ESA – European Space Agency
Perhaps SolACES most important result was furnishing proof that the current solar cycle features a considerably lower energy level for EUV radiation than preceding cycles. If this trend continues and is shown to hold true for other spectral regions as well, it could indicate that a lower temperature rise in our atmosphere due to solar radiation can, at least a little, counteract anticipated major global warming.
One mission – three instruments
The SOLAR research mission comprised three scientific experiments aimed at studying the sun: SOLSPEC from France, the Swiss SOVIM and SolACES from Fraunhofer IPM. These three experiments – each in its own sector – were intended to gather information on the solar spectrum.
Their task was to determine the sun’s total energy input into our climate system and to separate it from the climatic influences resulting from the impact of man. It is only on the basis of these very accurate solar radiation values that we can use modern climate models to clarify how individual climate factors interact and contribute to global warming.
The challenge of space
SolACES was used to measure extreme ultraviolet (EUV) radiation absorbed by the atmosphere and which thus cannot be measured from Earth. EUV radiation is directly related to solar activity and thus allows us to draw conclusions as regards solar energy input into our climate system.
Measuring the highly variable EUV region is extremely difficult. Consequently, Fraunhofer IPM developed a method which allows correction of spectrometer degradation typical of conditions in space and thus permits highly accurate measurement of the fluctuations in solar radiation.
So this was the first time scientists managed to continuously calibrate EUV spectrometers in space and thus limit measurement error to 10 percent – an accuracy which had not been achieved before. This measuring accuracy was crucial to the European Space Agency’s decision to prolong the experiment’s lifetime twice to a total of nine years. The laboratory is thus the longest running research experiment to have taken place on the ISS.
SolACES sets standards
SOLAR was ceremoniously deactivated on 15 February 2017 at the B.USOC control centre in Brussels, exactly nine years to the day after it commenced operation. There was a lot to celebrate: firstly, the performance of the measuring systems and the measuring method itself had been improved continuously and near-optimised. Secondly, thanks to SOLAR, climate research now has a dataset on solar activity whose quantity and quality are unparalleled.
This is why the measurements are to continue: a new measuring concept is to be developed for this in cooperation with the renowned World Radiation Centre in Davos. This concept involves combining SolACES spectrometers with highly precise Total Solar Irradiance (TSI) detectors and thus allowing the established SolACES measuring method to be utilised for the entire spectral region.
https://livestream.com/ESA/solar Video showing deactivation of SOLAR at the B.USOC control centre on 15 February 2017
Holger Kock | Fraunhofer-Gesellschaft
Global study of world's beaches shows threat to protected areas
19.07.2018 | NASA/Goddard Space Flight Center
NSF-supported researchers to present new results on hurricanes and other extreme events
19.07.2018 | National Science Foundation
A new manufacturing technique uses a process similar to newspaper printing to form smoother and more flexible metals for making ultrafast electronic devices.
The low-cost process, developed by Purdue University researchers, combines tools already used in industry for manufacturing metals on a large scale, but uses...
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
20.07.2018 | Power and Electrical Engineering
20.07.2018 | Information Technology
20.07.2018 | Materials Sciences | <urn:uuid:f2f08294-a997-4657-ab2f-f24c25a85a64> | 3.34375 | 1,386 | Content Listing | Science & Tech. | 32.855703 | 95,504,230 |
A Guide for New Web Developers - from a newbie to another
Published on Oct. 9, 2016
updated 1 year, 3 months ago
Find a persuasive reason to start
Finding the Right Resources
So here's the actual part about the resources I used and how I used themWith the resources available on the internet, such as Codecademy, Coursera and others, it's natural that we want to find out which ones are most worth our time. I started researching on the best ones to use - DON'T DO THIS EXCESSIVELY. This was my mistake - I spent too much time trying to decide which resource to use than ACTUALLY DOING SOME REAL LEARNING. Just pick one and get down to it, especially if you are just starting out. Once you think you've covered the basics, keep finding more information from other resources and you must remember to apply your knowledge on mini-projects and not let it rot in the dark corners of your brain.
1. List of ResourcesTo start off, here are the things that are important for any beginner to take note of. There are two main types of web developers: front-end and back-end developers:
- Front-end: Does the HTML, CSS, JS. Basically the person who does everything you actually see on the website.
- Back-end: I call these guys the unsung heroes because they are the ones that actually make the whole thing work, but the general public won't be able to easily appreciate what they do. Creating databases (blog posts like this are stored in these things!), configuring the server and actually delivering the website pages to the internet. Without them, anything on the front-end will forever only remain on your own desktop.
- Python Programming - Amazing website to learn python in a hands-on way. He provides textual tutorials which are basically transcripts of his video tutorials. He has tutorials about the Flask and Django frameworks for Web Development in Python - I went with Django because it had more things set in place, while Flask is more 'naked' and light-weight and you'd have to customize it yourself.
- Coding Entrepreneurs - Another great resource for the Django framework. He goes into more detail about the things you can do with Django.
2. How to Use Them
There's no secret to this - after you've picked up some of the basics, you should get down to applying the knowledge. Which begs the next big question - how do I find projects to do?
3. Finding Stuff to DoSet up your own webpage! That's what I did - I put together whatever knowledge I had of the front-end and back-end stuff into this page. Find inspirations elsewhere - such as these:
- Build a beautiful To-do List!
- Python: Automate the boring stuff with Python
- More inspiration on this Quora thread | <urn:uuid:445489bc-1ad9-4b95-bbc1-5a34ae02aaf8> | 2.703125 | 596 | Personal Blog | Software Dev. | 56.968371 | 95,504,235 |
Angular has its own vocabulary. Most Angular terms are common English words with a specific meaning within the Angular system.
This glossary lists the most prominent terms and a few less familiar ones that have unusual or unexpected definitions.
Ahead-of-time (AOT) compilation
AngularDart apps are compiled at build time (ahead of time), rather than at run time (just in time).
When unqualified, annotation refers to a Dart metadata
annotation (as opposed to, say, a type annotation). A metadata
annotation begins with the character
@, followed by either a reference
to a compile-time constant (such as
Component) or a call
to a constant constructor. See the metadata section
of the Dart language tour for details.
A category of directive that can listen to and modify the behavior of other HTML elements, attributes, properties, and components. They are usually represented as HTML attributes, hence the name.
For example, you can use the
ngClass directive to add and remove CSS class names.
Learn about them in the Attribute Directives guide.
Usually refers to data binding and the act of binding an HTML object property to a data object property.
To initialize and launch an Angular app.
You launch an Angular app using the runApp() function. In that function, you identify the app’s root component, which is the first component that is loaded for the app. You can optionally register service providers with the dependency injection system. For more information, see the Setup page.
The practice of writing compound words or phrases such that each word or abbreviation begins with a capital letter except the first letter, which is lowercase.
Function, property, and method names are typically spelled in camelCase. For example,
getHeroes. Notice that
square is an example of how you write a single word in camelCase.
camelCase is also known as lower camel case to distinguish it from upper camel case, or PascalCase. In Angular documentation, “camelCase” always means lower camel case.
An Angular class responsible for exposing data to a view and handling most of the view’s display and user-interaction logic.
@Component annotation to
the component class, thereby attaching to the class the essential component metadata
that Angular needs to create a component instance and render the component with its template
as a view.
Those familiar with “MVC” and “MVVM” patterns will recognize the component in the role of “controller” or “view model”.
The practice of writing compound words or phrases such that each word is separated by a dash or hyphen (
This form is also known as kebab-case.
Directive selectors (like
my-app) are often
spelled in dash-case.
Apps display data values to a user and respond to user actions (such as clicks, touches, and keystrokes).
In data binding, you declare the relationship between an HTML widget and data source and let the framework handle the details. Data binding is an alternative to manually pushing app data values into HTML, attaching event listeners, pulling changed values from the screen, and updating app data values.
Angular has a rich data-binding framework with a variety of data-binding operations and supporting declaration syntax.
Read about the following forms of binding in the Template Syntax page:
- Property binding.
- Event binding.
- Attribute binding.
- Class binding.
- Style binding.
- Two-way data binding with ngModel.
Decorator | decoration
A design pattern and mechanism for creating and delivering parts of an app to other parts of an app that request them.
Angular developers prefer to build apps by defining many simple parts that each do one thing well and then wiring them together at runtime.
These parts often rely on other parts. An Angular component part might rely on a service part to get data or perform a calculation. When part “A” relies on another part “B”, you say that “A” depends on “B” and that “B” is a dependency of “A”.
You can ask a “dependency injection system” to create “A” for us and handle all the dependencies. If “A” needs “B” and “B” needs “C”, the system resolves that chain of dependencies and returns a fully prepared instance of “A”.
Angular provides and relies upon its own sophisticated dependency-injection system to assemble and run apps by “injecting” app parts into other app parts where and when needed.
At the core, an
injector returns dependency values on request.
injector.get(token) returns the value associated with the given token.
A token is an Angular type (
OpaqueToken). You rarely need to work with tokens directly; most
methods accept a class name (
Foo) or a string (“foo”) and Angular converts it
to a token. When you write
injector.get(Foo), the injector returns
the value associated with the token for the
Foo class, typically an instance of
During many of its operations, Angular makes similar requests internally, such as when it creates a
component for display.
Injector maintains an internal map of tokens to dependency values.
Injector can’t find a value for a given token, it creates
a new value using a
Provider for that token.
A provider is a recipe for creating new instances of a dependency value associated with a particular token.
An injector can only create a value for a given token if it has
provider for that token in its internal provider registry.
Registering providers is a critical preparatory step.
Angular registers some of its own providers with every injector. You can register your own providers.
Read more in the Dependency Injection page.
An Angular class responsible for creating, reshaping, and interacting with HTML elements in the browser DOM. The directive is Angular’s most fundamental feature.
A directive is usually associated with an HTML element or attribute. This element or attribute is often referred to as the directive itself.
When Angular finds a directive in an HTML template, it creates the matching directive class instance and gives the instance control over that portion of the browser DOM.
You can invent custom HTML markup (for example,
associate with your custom directives. You add this custom markup to HTML templates
as if you were writing native HTML. In this way, directives become extensions of
Directives fall into one of the following categories:
Attribute directives can listen to and modify the behavior of other HTML elements, attributes, properties, and components. They are usually represented as HTML attributes, hence the name.
Structural directives are responsible for shaping or reshaping HTML layout, typically by adding, removing, or manipulating elements and their children.
Short hand for ECMAScript 2015.
Short hand for ECMAScript 2015.
A directive property that can be the target of a property binding (explained in detail in the Template Syntax page). Data values flow into this property from the data source identified in the template expression to the right of the equal sign.
A form of property data binding in which a template expression between double-curly braces renders as text. That text may be concatenated with neighboring text before it is assigned to an element property or displayed between element tags, as in this example.
Just-in-time (JIT) compilation
A way (no longer supported) of compiling components in the browser and launching apps dynamically. As of v5, AngularDart supports only ahead-of-time compilation.
You can tap into key moments in that lifecycle by implementing one or more of the lifecycle hook interfaces.
Each interface has a single hook method whose name is the interface name prefixed with
For example, the
OnInit interface has a hook method named
Angular calls these hook methods in the following order:
ngOnChanges: when an input/output binding value changes.
ngOnInit: after the first
ngDoCheck: developer’s custom change detection.
ngAfterContentInit: after component content initialized.
ngAfterContentChecked: after every check of component content.
ngAfterViewInit: after a component’s views are initialized.
ngAfterViewChecked: after every check of a component’s views.
ngOnDestroy: just before the directive is destroyed.
Read more in the Lifecycle Hooks page.
In this documentation, the term module refers to a Dart compilation unit, such
as a library or package. If a Dart file has no
directive, then that file itself is a library and thus a compilation
unit. For more information about compilation units, see
the Libraries and Scripts chapter in the
Dart Language Specification.
A directive property that can be the target of event binding (read more in the event binding section of the Template Syntax page). Events stream out of this property to the receiver identified in the template expression to the right of the equal sign.
The practice of writing individual words, compound words, or phrases such that each word or abbreviation begins with a capital letter.
Class names are typically spelled in PascalCase. For example,
This form is also known as upper camel case to distinguish it from lower camel case or simply camelCase. In this documentation, “PascalCase” means upper camel case and “camelCase” means lower camel case.
An Angular pipe is a function that transforms input values to output values for
display in a view.
Here’s an example that uses the built-in
currency pipe to display
a numeric value in the local currency.
You can also write your own custom pipes. Read more in the page on pipes.
A provider creates a new instance of a dependency for the dependency injection system. It relates a lookup token to code—sometimes called a “recipe”—that can create a dependency value.
Most apps consist of many screens or views. The user navigates among them by clicking links and buttons, and performing other similar actions that cause the app to replace one view with another.
The Angular component router is a richly featured mechanism for configuring and managing the entire view navigation process, including the creation and destruction of views.
An Angular component with a
RouterOutlet that displays views based on router navigations.
For more information, see the Routing & Navigation page.
For data or logic that is not associated with a specific view or that you want to share across components, build services.
Apps often require services such as a hero data service or a logging service.
A service is a class with a focused purpose. You often create a service to implement features that are independent from any specific view, provide shared data or logic across components, or encapsulate external interactions.
Apps often require services such as a data service or a logging service.
The practice of writing compound words or phrases such that an
_) separates one word from the next. This form is also known as underscore case.
Dart package names and filenames are spelled in snake_case, by
A category of directive that can
shape or reshape HTML layout, typically by adding and removing elements in the DOM.
ngIf “conditional element” directive and the
ngFor “repeater” directive are well-known examples.
Read more in the Structural Directives page.
A Dart-like syntax that Angular evaluates within a data binding.
The process of transforming code written in one language (for example, Dart or TypeScript) into another (such as ES5).
A portion of the screen that displays information and responds to user actions such as clicks, mouse moves, and keystrokes.
Angular renders a view under the control of one or more directives, especially component directives and their companion templates. The component plays such a prominent role that it’s often convenient to refer to a component as a view.
Views often contain other views. Any view might be loaded and unloaded dynamically as the user navigates through the app, typically under the control of a router.
Zones are a mechanism for encapsulating and intercepting a Dart app’s asynchronous activity.
Read more about zones in this article. | <urn:uuid:c440726f-1897-4469-8b60-250302bb8886> | 3.15625 | 2,634 | Structured Data | Software Dev. | 38.379702 | 95,504,247 |
sequence that no information is present at all; (3) al low subjects to suppose that the original information could be present but has been made inaudible ("hear through the noise") (Plomp, 1980). The third possibility is the one we briefly hinted at in our paper, where we said that this "possibility must not be excluded." The truth is, however, that we do not really know exactly what happens when noise is added to a si gnal; how, for example, would it provide "spectral continuity?" The fact that Ohde and Sharl's (1980) and our results are of the same magnitude could indicate that the effects caused by a time window or noise are the same, but it is too early to say that. We investigated the vibration of leaves of four plant species in a sound field using a laser-Doppler-vibrometer system. All leaves behave as linear mechanical systems when driven by sound and noise at sound pressure levels (SPL) of up to 100 dB re 20 µPa. The modes of vibration are complex in the investigated frequencies (O.S-S.S kHz}, and change with the orientation of the leaf in the sound field. The vibration velocities of the leaves varied between 10-' and 3X10-4 m/s, while the vibration velocity of the air particles is S X 10-3 m/s at 100 dB SPL. Although the amount of sound energy absorbed in this way by a single leaf is very small, this mechanism may anyhow contribute to sound attenuation by plants and plant communities, since the number of leaves of one fullgrown tree equals 2 X 1 O'.
Mendeley saves you time finding and organizing research
There are no full text links
Choose a citation style from the tabs below | <urn:uuid:720282a0-8531-46cc-b29d-256f3dcfb0bb> | 2.578125 | 367 | Academic Writing | Science & Tech. | 54.005054 | 95,504,270 |
On day 1 on the C# development, we should be aware about the basic variables used in C#.
Variables are like the store unit needed for the data storage while executing any program.
In C# variables are declared as below:
E.g. int a; string str;
The data types used to create a variables are of two types,
- Values Types:
The data types which are used to store the data which is allocated to the itself is called value types. The variable initialized as a value data type contains the value in it. The value types are stored in the stack memory.
E.g. Byte, int, float, char, double, decimal, bool etc.
- Reference Types:
The data types which holds the address/reference of the data are called reference types. The reference types are stored in the heap memory.
E.g. string, object.
Boxing & Unboxing:
Conversion of value of value type into value of reference type.
In boxing conversion permits any value type to be converted to the object type.
E.g. int a=1;
object b=a; //boxing
Conversion of value of reference type into value of value type.
In unboxing we perform explicit conversion of object type into value type.
E.g. object b=12;
int a=( int )b; //unboxing
Operators in C# are as below.
These include the operators used for mathematical purpose, like addition, subtraction, multiplication, division, modulus, increment & decrement operators.
- Addition (+)
- Subtraction (-)
- Multiplication (*)
- Division (/)
- Modulus (%)
- Increment (++)
- Decrement (–)
These include the operators which are used to perform logical operations like AND, OR & NOT.
- AND (&&)
- OR (||)
- NOT (!)
These includes the operators which are used for comparison purpose, like EQUAL TO, GREATER THAN & SMALLER THAN.
- EQUAL TO (==)
- NOT EQUAL TO (! ==)
- GREATER THAN (>)
- SMALLER THAN (<)
- GREATER THAN OR EQUAL TO (>=)
- SMALLER THAN OR EQUAL TO (<=) | <urn:uuid:398eaf22-3b2b-44af-acef-57b911d75eb8> | 3.96875 | 500 | Documentation | Software Dev. | 45.090339 | 95,504,289 |
The term potential predictability is used in the context of weather forecasting to describe the extent that the future weather can be predicted in principle, i.e., it describes the proportion of variance in the weather that arises from systematic factors rather than random noise.
Denote by the standard deviation in weather outcomes, so that is the variance in weather outcomes. Of this, denote by the internally generated variance component and by the unpredictable noise component. We have:
The potential predictability variance fraction (ppvf) is defined as:
The signal to noise ratio is defined as:
and can be computed from each other:
We have . Small values of indicate that the signal is small, and that the weather is inherently unpredictable. Values of close to 1 suggest that the weather is potentially predictable, even if current weather prediction methods do not predict it successfully.
- Boer, G. J. "Forced and internally generated 21st century decadal "potential predictability"" (PDF). Retrieved April 19, 2014.
- Boer, G. J. (March 2011). "Decadal potential predictability of twenty-first century climate". Climate Dynamics. 36 (5-6): 1119–1133. doi:10.1007/s00382-010-0747-9.
- Tiedge, Bente; Köhl, Armin; Baehr, Johanna (December 2012). "Potential Predictability of the North Atlantic Heat Transport Based on an Oceanic State Estimate". Journal of Climate. American Meteorological Society. 25 (24): 8475–8486. doi:10.1175/JCLI-D-11-00606.1.
- Waliser, Duane; Stern, William; Lau, K. M.; Jones, Charles. "Potential Predictability of the Madden–Julian Oscillation" (PDF).
- Gianotti, Dan; Anderson, Bruce; Salvucci, Guido. "Potential Predictability of Precipitation: Occurrence or Intensity?" (PDF). Retrieved April 19, 2014.
- Mohan, R. S. Ajaya; Goswami, B. N. (June 12, 2003). "Potential predictability of the Asian summer monsoon on monthly and seasonal time scales". Meteorological and Atmospheric Physics. doi:10.1007/s00703-002-0576-4. | <urn:uuid:6f93b244-7a59-4063-833f-56e2a0addbb8> | 2.671875 | 499 | Knowledge Article | Science & Tech. | 51.251123 | 95,504,294 |
A low pressure system associated with former Tropical Storm Beryl reorganized north of Bermuda on Saturday and the National Hurricane Center designated the system as Subtropical Storm Beryl. At 2:00 p.m. EDT on Saturday the center of Subtropical Storm Beryl was located at latitude 36.4°N and longitude 65.7°W which put it about 575 miles (930 km) south-southwest of Halifax, Nova Scotia. Beryl was moving toward the northeast at 12 m.p.h. (19 km/h). The maximum sustained wind speed was 40 m.p.h. (65 km/h) and there were wind gusts to 50 m.p.h. (80 km/h). The minimum surface pressure was 1010 mb.
The remnants of former Tropical Storm Beryl moved slowly across the northern Caribbean Sea and then over the southeastern Bahamas to a position northwest of Bermuda. A low pressure system formed at the surface. Bands of showers and thunderstorms developed and began to revolve around the the low pressure system. The low pressure system moved under the eastern side of an upper level trough. The trough contains colder air in the upper levels and it was also producing southwesterly winds which were blowing toward the top of the surface low pressure system. The southwesterly winds were generating moderate vertical wind shear and the strongest rainbands were occurring on the eastern side of the surface low. Some drier air was moving around the western and southern part of the upper level trough, which may have contributed to the weaker bands on the western side of the circulation. The presence of the upper level trough and the asymmetrical distribution of thunderstorms around the surface low prompted the National Hurricane Center to designate the system as a subtropical storm.
Subtropical Storm Beryl will move through an environment marginally favorable for intensification during the next 24 hours. Beryl will move over water where the Sea Surface Temperature is near 26°C. The upper level trough will continue to produce moderate vertical wind shear. The wind shear and the drier air will inhibit intensification. Subtropical Storm Beryl could intensify a little more during the next 24 hours. Beryl will move over colder water later on Sunday and it will start to weaken when that occurs.
The upper level trough was steering Subtropical Storm Beryl toward the northeast and a general motion in that direction is forecast to continue for several more days. On its anticipated track Subtropical Storm Beryl will pass south of Nova Scotia on Sunday. Beryl could be near Newfoundland by Tuesday.
Hurricane Chris weakened slowly on Wednesday as it passed well south of Nova Scotia. At 11:00 p.m. EDT on Wednesday the center of Hurricane Chris was located at latitude 39.6°N and longitude 63.0°W. Chris was moving toward the northeast at 29 m.p.h. (46 km/h). The maximum sustained wind speed was 85 m.p.h. (140 km/h) and there were wind gusts to 100 m.p.h. (160 km/h). The minimum surface pressure was 980 mb.
Hurricane Chris exhibited the structure of a hurricane on Thursday, but the clouds did not rise quite as high because it was over slightly cooler water. There was still an eye at the center of circulation. Several bands of showers and thunderstorms were revolving around the core of the circulation. The rainbands were weaker in the southwestern part of the hurricane because some drier air was entering that part of the circulation. Storms in the core of the circulation were generating upper level divergence.
Hurricane Chris is likely to weaken again on Thursday. It will start to move over much cooler water where there is less energy in the upper ocean. In addition an upper level trough over the eastern U.S. will produce southwesterly winds which will blow toward the upper part of the hurricane. Those winds will cause strong vertical wind shear. The shear will undercut the upper level divergence and tilt the circulation toward the northeast with height. Hurricane Chris will start to make a transition to an extratropical cyclone when the effects of the cooler water and stronger shear begin to alter the structure of the hurricane.
The upper level trough was steering Hurricane Chris rapidly toward the northeast and that motion is expected to continue for several more days. On its anticipated track Hurricane Chris will be near Labrador on Thursday night. The extratropical cyclone that results from the transition of Hurricane Chris will be near Iceland during the weekend.
Former Tropical Storm Chris strengthened to a hurricane southeast of Cape Hatteras on Tuesday. At 5:00 p.m. EDT on Tuesday the center of Hurricane Chris was located at latitude 33.7°N and longitude 72.4°W which put it about 205 miles (330 km) east-southeast of Cape Hatteras, North Carolina. Chris was moving toward the northeast at 10 m.p.h. (16 km/h). The maximum sustained wind speed was 85 m.p.h. (135 km/h) and there were wind gusts to 100 m.p.h. (160 km/h). The minimum surface pressure was 980 mb.
Hurricane Chris strengthened on Tuesday when it moved northeast of cooler water Chris had mixed to the surface while it was meandering off the coast of the Carolinas. An eye with a diameter of 30 miles (50 km) formed at the center of circulation. A ring of strong thunderstorms surrounded the eye and the strongest winds were occurring in the eastern side of that ring of storms. Bands of showers and thunderstorms were revolving around the core of Hurricane Chris. The strongest rainbands were in the eastern half of the circulation. Drier air near the western half of the circulation was contributing to the weaker bands in that part of the hurricane. Storms in the core of the circulation were generating upper level divergence which was pumping mass away to the north and east of the hurricane. Winds to hurricane force extended out about 20 miles (30 km) from the center of circulation. Winds to tropical storm force extended out about 95 miles (155 km) from the center.
Hurricane Chris will move through an environment favorable for intensification on Wednesday. Chris will move over water where the Sea Surface Temperature is near 28°C. An upper level trough over the northeastern U.S. will produce southwesterly winds that will blow toward the top of the hurricane. The winds speeds are similar at most levels and they will not generate a lot of vertical wind shear during the next 24 hours. Hurricane Chris will strengthen on Wednesday and it could intensify rapidly. Chris will move over cooler water when it gets north of the Gulf Stream and it will start to weaken when that occurs.
The trough over the northeastern U.S. will steer Hurricane Chris toward the northeast. On its anticipated track Chris will move away from the coast of North Carolina. Chris could be south of Nova Scotia in about 36 hours and it could be near Newfoundland in several days.
Elsewhere, the remnants of former Tropical Storm Beryl crossed Hispaniola and they were moving toward the southeastern Bahamas. At 2:00 p.m. EDT on Tuesday the center of Former Tropical Storm Chris was located at latitude 20.1°N and longitude 72.6°W which put it about 40 miles (65 km) northeast of Port de Paix, Haiti. It was moving toward the northwest at 17 m.p.h. (28 km/h). The maximum sustained wind speed was 35 m.p.h. (55 km/h) and there were wind gusts to 45 m.p.h. (75 km/h). The minimum surface pressure was 1013 mb. A reconnaissance aircraft is scheduled to investigate the system on Wednesday if there are signs that it could be reorganizing into a tropical cyclone.
Kate intensified into the fourth Atlantic hurricane of 2015 as it raced northeastward. At 10:00 a.m. EST on Wednesday the center of Hurricane Kate was located at latitude 36.8°N and longitude 60.5°W which put it about 395 miles (635 km) northeast of Bermuda and about 780 miles (1160 km) south-southwest of Cape Race, Newfoundland. Kate was moving toward the northeast at 45 m.p.h. (72 km/h). The maximum sustained wind speed was 75 m.p.h. (120 km/h) and there were wind gusts to 90 m.p.h. (145 km/h). The minimum surface pressure was 985 mb.
The organization of Hurricane Kate improved on Wednesday when a partial eyewall wrapped around the northern and western sides of the center of circulation. The structure of Kate is somewhat tilted toward the northeast by stronger southwesterly wind in the upper levels of the atmosphere. However, Kate currently has a warm core and it is still a tropical cyclone. Kate is moving over water where the Sea Surface Temperature (SST) is near 25°C. In a day or so the effects of strong vertical wind shear and cooler SSTs will cause Hurricane Kate to begin a transition to an extratropical cyclone.
Strong westerly winds are steering Kate rapidly toward the northeast and that general motion is expected to continue during the next few days. Kate could approach the United Kingdom as a strong extratropical cyclone during the weekend.
An instrument on a satellite indicated that there could be surface winds to tropical storm force in an area of thunderstorms east of the center of Tropical Depression Eight and the National Hurricane Center designated the system as Tropical Storm Henri. At 11:00 p.m. EDT on Wednesday the center of Tropical Storm Henri was located latitude 31.3°N and longitude 60.7°W which put it about 250 miles (405 km) east-southeast of Bermuda. Henri was moving toward the north at 5 m.p.h. The maximum sustained wind speed was 40 m.p.h. (65 km/h) and there were wind gusts to 50 m.p.h. (80 km/h). The minimum surface pressure was 1008 mb.
Henri is not a very well organized tropical storm. An upper level low centered north of Bermuda is causing brisk southwesterly winds over the top of Henri. The vertical wind shear is blowing the tops off of thunderstorms that start to form near the center of circulation. As a result of the wind shear, the stronger thunderstorms are all located well to the east of the center of the tropical storm. Henri is over warm Sea Surface Temperatures (SSTs) which are above normal in that part of the western Atlantic Ocean. So, there is plenty of energy to support intensification. However, as long as the upper level low creates significant vertical wind shear, intensification will be minimal. It is possible that as Henri moves toward the north that the wind shear could decrease. In that case Henri could intensify during the next day or two before it moves over cooler SSTs.
An upper level trough over the eastern U.S. should steer Henri toward the north during the next several day. On its anticipated track, Henri could pass near Newfoundland during the weekend. Henri could be in the process of transitioning from a tropical storm to an extratropical cyclone at that time, but it could still bring strong winds and rain to parts of extreme eastern Canada. | <urn:uuid:f9375eab-7a15-4e5f-8fab-ae3880c72379> | 2.734375 | 2,358 | Content Listing | Science & Tech. | 67.861416 | 95,504,299 |
FireWatir is a web application testing tool written using Ruby language. It is used for testing web application functionality on Firefox browser. It is written keeping 'WATiR' in mind so that scripts written for testing the application on IE using WATiR can be used with minimal/no changes, to test the application on Firefox.
How its different from WATiR?
The main difference between WATiR and FireWatir lies in the mechanism, which drives the browser, to test a web application.
WATiR uses the COM object of IE browser exposed by windows. It interacts with the COM objects for doing any action on HTML elements, of a page, that is displayed using IE(i.e. HTML elements that are supported by WATiR). Interacting with the browser in this way restricts the usage of WATiR on Windows only.
So, finally the test scripts when executed on IE or FireFox will be executed in same manner; the working is transparent to users. Though, FireWatir is implemented using socket for interaction with the browser, there is not much of a difference in execution speed of FireWatir as comparted to WATiR.
How to install FireWatir?
You can get the latest gem and JSSh extension for Windows from http://code.google.com/p/firwatir. FireWatir is still not tested on Mac or Linux, but it should work on any platform as we are not using any Windows specific component.
Install the JSSh extension by opening the extension file in the browser. The extension will not show up in the extension list. So to check if the extension is installed properly, restart the Firefox from command prompt with '-jssh' as command line argument. For e.g.: In windows restart it using 'c:\Program Files\Mozilla Firefox\Firefox.exe -jssh' assuming that you have installed Firefox in 'c:\Program Files\Mozilla Firefox' directory. After the browser is started telnet to port 9997. the response should be:
JSSh command shell will open with '>' as shell prompt character. If this shows up then JSSh extension is installed properly.
Install the FireWatir gem using command 'gem install [firewatir gem name]'. This will install FireWatir 1.0 on your machine. Now go to the FireWatir installation directory in the gems. For e.g. go to 'c:\ruby\lib\ruby\gems\1.8\gems' assuming that you are on windows platform and have installed 'ruby' version 1.8 in 'c:\ruby\' directory. Check for 'firewatir-1.0-mswin32 folder (assuming you have installed gem for windows). Existence of that folder indicates correct installation. Now go to 'unittests' directory and run file 'mozilla_all_tests.rb' (make sure you have started Firefox as said above with -jssh option before running the test cases). This file will run all the unittests without any failure or errors. In case you get any errors or failures refer to section 'TroubleShooting'. In case the error is not resolved add it to the issue tracking system at 'http://code.google.com/p/firewatir.
How to use?
Go to the 'unittests' directory in the gems folder. Refer to the unittest cases on how to access the element? How to use them? What properties they expose? etc etc..
Which Firefox versions are supported?
FireWatir is tested on Firefox version 1.5, 188.8.131.52 and 2.0. It should work with all Firefox version 1.5 and above. It may or may not work with versions less that 1.5
1. Currently you need to start Firefox manually from command prompt using '-jssh' as command line argument before running any FireWatir script or unit tests.
2. Check if JSSh is installed correctly by connecting to port 9997 using Telnet (telnet localhost 9997 if you are telnet-ing from the same machine on which your Firefox instance is running, or telnet testhost 9997 where testhost is the hostname of the remote machine on which FireFox is running).
3. In case 'attach_new_browser' test fails. Make sure you run this test alone using 'ruby attach_new_browser'. Make sure that Firefox doesn't block the pop up. Also make sure that you have settings to open the link in new window instead of new tab.
4. In case you face any other problems or you have some comments/suggestions/queries mail at 'firstname.lastname@example.org' or at 'email@example.com' | <urn:uuid:f114c68d-4000-400f-8075-08cd5360d8c6> | 3.078125 | 1,023 | Tutorial | Software Dev. | 60.861084 | 95,504,326 |
Prototypes of the devices, which need no electricity or fuel, were the topic of one of the keynote addresses at the opening of the 246th National Meeting & Exposition of the American Chemical Society (ACS), the world's largest scientific society. The meeting, which features almost 7,000 reports on new advances in science and other topics, continues through Thursday in the Indiana Convention Center and downtown hotels.
Naomi Halas, D.Sc., pointed out that almost 2 billion people live in areas of the world without a regular supply of electricity. That electricity is key to using machines called autoclaves, which produce scorching-hot steam to sterilize medical and dental instruments. Without that basic machine, doctors must rely on chemicals, which can be costly and difficult to transport, to prevent the spread of germs and disease from medical and dental instruments.
"We have developed a solution, our solar steam technology," Halas said. She is with Rice University. "It is completely off-grid, uses sunlight as the energy source, is not that large, kills disease-causing microbes effectively and relatively quickly and is easy to operate. This is an incredibly promising technology."
Halas and colleagues have prototypes of two solar steam machines. One is the autoclave for sterilizing medical and dental instruments. The second is an autoclave for disinfecting human and animal wastes, which are another major source of disease transmission in developing countries and other resource-limited areas. The technology could be expanded to provide steam for direct use in purifying dirty or salty water for drinking and cooking — with the solar-generated steam simply allowed to condense into pure distilled water. Possibilities also exist for adapting the technology to produce steam to spin small electric turbines to generate electricity.
Their tests showed that the prototype autoclaves produced steam at temperatures ranging from 239 to 270 degrees Fahrenheit. Steam production adequate for sterilization began within about 5 minutes. It continued for periods of time long enough to sterilize liquid and solid materials placed inside the device, consistent with U.S. Food and Drug Administration sterilization guidelines. The heat and pressure produced by the steam was great enough to kill the most heat-resistant living microbes, and also viruses and the tough spores that microbes form to survive hostile environmental conditions.
The autoclaves are the first practical applications of a new solar energy technology described earlier in 2012 in ACS Nano, one of the ACS' more than 40 peer-reviewed scientific journals. Metallic nanoparticles — bits of material so small that hundreds would fit inside the period at the end of this sentence — go into a container of water. Sunlight focused into the water quickly heats the nanoparticles, which scientists are terming "nanoheaters." A layer of steam forms on the nanoheaters and buoys them up to the water's surface. They release the steam and sink back down into the water to repeat the process.
"Nanoheaters generate steam at a remarkably high efficiency," Halas said. "More than 80 percent of the energy they absorb from sunlight goes into production of steam. In the conventional production of steam, you would have to heat the entire container of water until it boils, with the bubbles rising to the top to release steam. With nanoheaters, less than 20 percent of the energy heats the neighboring liquid."
The prototype autoclaves consist of a dish-like mirror that focuses sunlight into a container of water with the nanoheaters.
A video on the solar heater technology is available here.
Halas recently formed a company that is working on moving the devices from the prototype stage to commercial products. She and her collaborators are seeking ways to make them more rugged and at a more reasonable cost. They are also exploring even more applications for the technology.
A press conference on this topic will be held Sunday, Sept. 8, at 1 p.m. in the ACS Press Center, Room 211, in the Indiana Convention Center. Reporters can attend in person or access live audio and video of the event and ask questions at http://www.ustream.tv/channel/acslive.
Halas acknowledged funding from the Bill and Melinda Gates Foundation.
The American Chemical Society is a nonprofit organization chartered by the U.S. Congress. With more than 163,000 members, ACS is the world's largest scientific society and a global leader in providing access to chemistry-related research through its multiple databases, peer-reviewed journals and scientific conferences. Its main offices are in Washington, D.C., and Columbus, Ohio.
To automatically receive news releases from the American Chemical Society, contact email@example.com.
Note to journalists: Please report that this research was presented at a meeting of the American Chemical Society.
Michael Bernstein | EurekAlert!
Scientists uncover the role of a protein in production & survival of myelin-forming cells
19.07.2018 | Advanced Science Research Center, GC/CUNY
NYSCF researchers develop novel bioengineering technique for personalized bone grafts
18.07.2018 | New York Stem Cell Foundation
A new manufacturing technique uses a process similar to newspaper printing to form smoother and more flexible metals for making ultrafast electronic devices.
The low-cost process, developed by Purdue University researchers, combines tools already used in industry for manufacturing metals on a large scale, but uses...
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
20.07.2018 | Power and Electrical Engineering
20.07.2018 | Information Technology
20.07.2018 | Materials Sciences | <urn:uuid:0a182165-8152-4256-83fa-a99937546e37> | 3.5 | 1,558 | Content Listing | Science & Tech. | 37.954771 | 95,504,340 |
SI-Traceable Water Content Measurements in Solids, Bulks, and Powders
- 96 Downloads
Methods such as Karl Fischer titration and Loss-on-Drying, commonly used for estimating moisture content in samples, have been in existence for many years, but have difficulties obtaining a direct calibration chain toward water content. In recognition of this challenge, the joint research project, METefnet, was funded by the European Metrology Research Programme in 2012. The goal of METefnet is to establish a European metrology infrastructure for water content measurement and to develop primary standards for unambiguous determination of water mass fraction in materials. Here, we describe the primary standard developed by Danish Technological Institute in METefnet. This standard establishes traceability of the water content of a sample to dewpoint temperature. The standard only measures water, and the measurement result is not affected by other components.
KeywordsDew point Moisture content SI primary standard Water content Water mass fraction
The EMRP is jointly funded by the EMRP participating countries within EURAMET and the European Union.
- 1.International Organisation for Standardization. http://www.iso.org/iso/home.html. Accessed 30 Apr 2015
- 2.En 14774-1:2004 solid biofuels—determination of moisture content—oven dry method. Standard, European Standard (2004)Google Scholar
- 3.En 5537:2004 dried milk—determination of moisture content (reference method). Standard, European Standard (2004)Google Scholar
- 6.E. Scholz, Karl Fischer Titration: Determination of Water (Springer, Berlin, 1984)Google Scholar
- 8.H. Robain, C. Camerlynck, G. Bellier, A. Tabbagh, Geophys. Res. Abstr. 5, 03830 (2003)Google Scholar
- 11.P. Österberg, M. Heinonen, M. Ojanen-Saloranta, A. Mökynen, Proceedings of XXI IMEKO World Congress, Prague, Czech Republic, 2015 (2016)Google Scholar
- 14.S. Bell, R. Aro, F. Arpino, S. Aytekin, G. Cortellessa, M. Dell’Isola, Z. Ferenčíková, V. Fernicola, R. Gavioso, E. Georgin, M. Heinonen, D. Hudoklin, L. Jalukse, N. Karaböce, I. Leito, A. Mäkynen, P. Miaov, J. Nielsen, I. Nicolescu, M. Rudolfová, M. Ojanen-Saloranta, P. Österberg, P. Østergaard, M. Rujan, M. Sega, R. Strnad, T. Vachova, Proceedings of 17th International Conference of Metrology (CIM2015), Paris. France (2015). https://doi.org/10.1051/metrology/20150015003
- 15.International vocabulary of metrology—basic and general concepts and associated terms (VIM). JCGM 200:2012, JCGM (2012)Google Scholar
- 17.B. Hardy, The Proceedings of the Third International Symposium on Humidity and Moisture (1998), pp. 1–8Google Scholar
- 19.M. Heinonen, S. Bell, B.I. Choi, G. Cortellessa, I. Crina-Nicolescu, V. Fernicola, E. Georgin, D. Hudoklin, N. Ismail, T. Keawprasert, M. Krasheninina, I. Leito, J. Nielsen, S.O. Aytekin, P. Osterberg, J. Skabar, R. Strnad, TEMPMEKO 2016 (2016)Google Scholar
- 20.P. Miao, P. Carroll, S. Bell, C. Spray, R. Aro, I. Crina-Nicolescu, M.S. Eroglu, V. Fernicola, P.F. Østergaard, N. Karaboce, I. Leito, J. Nielsen, S.O. Aytekin, F. Rolle, M. Sega, TEMPMEKO 2016 (2016)Google Scholar | <urn:uuid:4d824d8f-f396-4739-bb96-47f0706a07ff> | 2.625 | 939 | Academic Writing | Science & Tech. | 62.952464 | 95,504,396 |
Prof. R. van Grondelle:The quantum design of photosynthesis
|Wanneer:||vr 29-05-2015 13:00 - 14:00|
Photosynthesis has found an ultrafast and highly efficient way of converting the energy of the sun into electrochemical energy. The solar energy is collected by Light-Harvesting complexes (LHC) and then transferred to the Reaction Center (RC) where the excitation energy is converted into a charge separated state with almost 100% efficiency. That separation of charges creates an electrochemical gradient across the photosynthetic membrane which ultimately powers the photosynthetic organism. The understanding of the molecular mechanisms of light harvesting and charge separation will provide a template for the design of efficient artificial solar energy conversion systems.
Upon excitation of the photosynthetic system the energy is delocalized over several cofactors creating collective excited states (excitons) that provide efficient and ultrafast paths for energy transfer using the principles of quantum mechanics. In the reaction center the excitons become mixed with charge transfer (CT) character (exciton-CT states), which provide ultrafast channels for charge transfer. However, both the LHC and the RC have to cope with a counter effect: disorder. The slow protein motions (static disorder) produce slightly different conformations which, in turn, modulate the energy of the exciton-CT states. In this scenario, in some of the LHC/RC complexes within the sample ensemble the energy could be trapped in some unproductive states leading to unacceptable energy losses.Here I will show that LHCs and RCs have found a unique solution for overcoming this barrier: they use the principles of quantum mechanics to probe many possible pathways at the same time and to select the most efficient one that fits their realization of the disorder. They use electronic coherence for ultrafast energy and electron transfer and have selected specific vibrations to sustain those coherences. In this way photosynthetic energy transfer and charge separation have achieved their amazing efficiency. At the same time these same interactions are used to photoprotect the system against unwanted byproducts of light harvesting and charge separation at high light intensities | <urn:uuid:e715cf88-d83d-4324-a51c-93f80aaec5fd> | 2.734375 | 441 | News (Org.) | Science & Tech. | 17.215 | 95,504,409 |
Who invented the current mathematical plus and minus signs?
The likelihood is that the signs (+) and negative (-) derive from the associated math operations of addition (+) and subtraction (-) when performed on a null set (zero). The Welsh mathematician Robert Recorde (1510-1558), the designer of the equals (=) sign, introduced the modern use of plus and minus symbols to the UK in 1557. The Chinese worked with negative numbers as early as 200 AD, and mathematicians in India (either concurrently or later) used the (+) sign for negative numbers. Resistance to negative solutions was expressed by the Greeks, and later by Europeans as late as the year 1800. This seems hard to explain when we see that businesses routinely used "credits" and "debits" to their accounts during the entire period.
1 person found this useful
Michael Stifel in 1544..
This is non-sensical.
In addition and subtraction, if the plus sign is larger than theminus sign, then it's a plus. For example: +10 minus -20 = -10 If the plus sign is smaller than the minus sig…n, the answer will bea minus. For example: -10 minus + 20 = -10 In multiplication, if you have 2 plus signs, the answer will be aplus sign. If you have 2 minus signs, the answer will be a plussign then, too. But if you have a plus and a minus sign, then theanswer will be a minus. For example: +5 x + 2 = +10 -5 x - 2 = +10 -5 x +2 = -10
go to the character map in the start menu. (for PC)
none other than Kate Punzalan
Michael Stifel in 1544.
How is the plus and minus voltage sign for resistance voltage drops for battery voltages and currents be determined?
The plus and minus voltage sign for resistance voltage, drops for battery voltages, and drops for currents is determined by convention. You can use whatever method you want -… so long as your use is consistent, your analytical results will be correct for you. . The commonly accepted convention, however, is best. This way, other people reviewing your results will not be confused unless, of course, they use an atypical convention. . Electric current flow is electron flow. The battery terminal marked "negative", or the cathode, is the source of electrons, and those electrons are drawn to, and flow towards, the "positive" terminal, or anode. . Consider a simple circuit, consisting of a battery in series with a resistor. Draw the battery on the left, with the anode up. Draw the resistor on the right. Connect the anode to the top of the resistor, and the cathode to the bottom of the circuit. (Actually, this is also a parallel circuit, with the battery in parallel with the resistor. It depends on how you see it, because this is a simple circuit.) . Current flows out of the bottom (cathode, negative) battery terminal, into the bottom of the resistor, up through the resistor to its top, over to the left, and into the top (anode, positive) battery terminal, and down through the battery, completing the circuit at the cathode. This is counter-clockwise, if you have drawn the circuit as stated. . If you place a voltmeter across the battery, you will see that the anode (top) is more positive than the cathode. If you place a voltmeter across the resistor, you will see that the top is more positive than the bottom. It does not matter if you measure across the battery or the resistor, the voltage will be the same. If you place the voltmeter across the wire on the bottom, or across the wire on the top, you will see that the voltage is zero. . With the preliminaries out of the way, now to the convention. . Current flow is counter-clockwise, from cathode to anode. If you were to draw a current arrow, you could draw it counter-clockwise, down through the battery and up through the resistor. You would label the first point that the current encounters (the bottom of the resistor) as negative, or minus. As the current goes through the resistor, it becomes more positive, so you would label the top of the resistor positive, or plus. Go over to the anode. That is also plus. The current is made more negative due to the battary being a source, rather than a load, so the cathode is minus. . These pluses and minuses are relative to each other, and they are also relative to some common reference point, said point by convention being the cathode. In this simple circuit, there is only one point that has any voltage different than the cathode, and that is the anode, so this distinction might be vague. . Consider then, the case where the resistor is actually two resistors in series. Again, the bottom resistor starts minus on its connection to the cathode, it becomes more positive as the current goes up, making the top of the bottom resistor plus. The bottom of the top resistor is minus, because current is flowing into it, and it becomes more positive as the current goes up, with the top of the top resistor plus. . When you measure voltage across an element, you see the voltage for that element. If, instead, you measure the voltage relative to the common reference point, and there is more than one element between the voltmeter's leads, you add up the voltage rises or drops to figure out what to expect. In fact, this is the basis for Kirchoff's voltage law - that the signed sum of the voltage drops around a series circuit always adds up to zero. . So, this preliminary convention is that current flow leaves the minus terminal of a voltage or current source, and enters the minus terminal of a voltage or current load. It then enters the plus terminal of a voltage or current source, and leaves the plus terminal of a voltage or current load. . Now, to confuse you, another convention states that current flows from plus to minus, not from minus to plus. This means that current leaves the plus terminal of a source, and enters the plus terminal of a load, and it enters the minus terminal of a source and leaves the minus terminal of a load. . It does not really matter which convention you use. The positions of the plus and minus signs will be the same - its just that the current arrow will point in the opposite direction - in this example, clockwise instead of counter-clockwise. What is important is to be consistent in your use of the plus or minus sign as the current enters and leaves a source or a load. . The convention of current flow is arbitrary. So long as you are consistent in your application, you will get the correct results. . It is generally accepted that current flow is electron flow, which means that current flows from the negative side of a voltage or current source towards the positive side. . Often, however, current is considered to flow from positive to negative. While this makes perception in circuit analysis more straightforward, it does not change the analytical results.
The plus sign (+) should be at the top of your keyboard. If there is another symbol below it on the same key, then you need to hit "shift" and the "+" sign so it won't print t…he other symbol that's below it. The minus sign ( - ) should also be at the top of your keyboard. The same instructions apply to it as to the + sign.
No one invented the minus sign or at least none that we know of, it is simply part of the evolution of mathmatics. The minus sign we use appeared in the 1400s
It indicates "plus or minus".
What prefixes an be used in mathematical expression consisting of two terms connected by a plus or minus sign?
aba, Malay ko sayo wiki.answers.com BOBO mo kasi
Michael Stifel in 1544..
In Math History
The person who invented the plus sign is the same as the minus
Shift-Option-Plus (+) will produce the ± symbol on a Mac.
plus or minus. You see it often with square roots. The square rootof 9 is plus or minus 3.
They are indicators of additive opposites. | <urn:uuid:fd156825-e62d-43ab-b5d5-596d13519227> | 3.4375 | 1,740 | Q&A Forum | Science & Tech. | 58.726943 | 95,504,483 |