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 |
|---|---|---|---|---|---|---|---|
BONN, Germany – The Latest on the global climate talks taking place in Germany (all times local):
Brazil says the rate of deforestation in its Amazon conservation areas fell by 28 percent over the past year, the second lowest level in decades.
The Latin American nation says satellite data show 159 square kilometers (61 square miles) of protected rainforest were destroyed in the 12 months ending July 2017.
That compares with a loss of 221 square kilometers of protected Amazon rainforest in the previous year.
Brazil is under pressure to clamp down on deforestation, much of it illegal, because the Amazon is plays a key role in soaking up carbon emissions and preserving biodiversity.
The announcement Tuesday on the sidelines of a global climate conference in Bonn, Germany, comes as Britain and Germany pledged $81 million and $72 million respectively to combat deforestation in the Amazon region.
Microsoft says it aims to cut carbon emissions generated from its operations by 75 percent by 2030, from 2013 levels.
The software giant's pledge Tuesday on the sidelines of global climate talks in Bonn, Germany, reflects the kinds of efforts large businesses are making to help curb climate change, which is largely caused by greenhouse gases such as carbon dioxide.
Microsoft has already cut its emissions from 900,000 metric tons of carbon dioxide equivalent in 2013 to about 230,000 tons this year, taking it a long way toward the stated goal for 2030.
But its electricity requirements will grow as the company expands its business, particularly in the field of cloud computing. The Redmond, Washington-based company said it wants to lower emissions by sharply increasing its use of renewable energy. | <urn:uuid:12dd98d9-f8c0-4346-beb8-8fd9f2d8ab56> | 2.796875 | 328 | News Article | Science & Tech. | 31.573571 | 95,636,908 |
See the attached diagram.
A block of wood that is 3 inches wide x 6 inches long x .380 inches thick is fixed/anchored to a structure.
The top surface of the wood block is heated to 300 degrees C. The bottom surface is cooled to an undetermined temperature.
The differential in temperature causes the top surface to expand/elongate while the bottom wood surface contracts. The difference in the expansion and contraction causes the end of wood block to deflect/deform by 1.25 inches.
The wood properties as well as a thermal conductivity are given.
1) Determine the cold temperature on the bottom surface of the wood that would cause enough temp differential between the hot & cold to cause the end of the wood to deflect as shown.
2) Based on the deflection of 1.25 inches, we are also asked to determine the vertical force, horizontal force, and actual force that caused the deformation.
If this were a traditional structural mechanics problem, I could reasonably determine that the vertical load (P) that could cause a deflection of 1.25 inches is approx. 144 lbs.© BrainMass Inc. brainmass.com July 18, 2018, 4:35 pm ad1c9bdddf
The deformation of blocks of wood when one surface is heated is determined. | <urn:uuid:4175c408-36c1-447d-8792-34aefffb21d2> | 3.671875 | 271 | Q&A Forum | Science & Tech. | 62.2232 | 95,636,938 |
Microscopic aspects of fracture: Cohesive stress
If we consider an unfaulted material with a crystalline structure, such as the simple cubic cell, which is characterised on the dimensional scale by the lattice parameter ao of the order of 0.5 mn, the possibilities of ordered and bulk deformation (Fig. 1.1), at temperatures that are low compared to the melting point, correspond to the answer to the two components of a force acting on a reticular or crystallographic plane: a stress normal to this plane and a shear stress parallel to this plane. The critical values required to ensure these motions and break the interatomic bond are called the theoretical cohesive stress (or cleavage stress) and the theoretical gliding stress (or shear stress).
KeywordsShear Stress Shear Modulus Titanium Alloy Graphic Plane Fracture Mode
Unable to display preview. Download preview PDF. | <urn:uuid:d573dea1-eea0-41a6-9c6b-d38640cbb5a9> | 2.8125 | 186 | Truncated | Science & Tech. | 34.255 | 95,636,941 |
Memory limit: 32 MB
There is given a rectangular bitmap of size . Each pixel of the bitmap is either white or black, but at least one is white. The pixel in -th line and -th column is called the pixel . The distance between two pixels and is defined as:
Write a program which:
- reads the description of the bitmap from standard input,
- for each pixel, computes the distance to the nearest white pixel,
- writes the results to the standard output.
In the first line of the standard input there is a pair of integer numbers , separated by a single space, , . In each of the following lines of the input exactly one zero-one word of length , the description of one line of the bitmap, is written. On the -th position in the line , , , is 1 if, and only if the pixel is white.
In the -th line of the standard output, , there should be written integers separated by single spaces, where is the distance from the pixel to the nearest white pixel.
For the input data:
3 4 0001 0011 0110
the correct result is:
3 2 1 0 2 1 0 0 1 0 0 1
Task author: Marcin Sawicki.<Submit a solution> [0/100] | <urn:uuid:04b16ab1-932c-429c-b31d-0cfd61227e5e> | 3.71875 | 272 | Tutorial | Software Dev. | 64.91637 | 95,636,942 |
Events in C# are, like in Delphi (or should I say Object Pascal) just properties of a class. Events are method pointers that delegate a call to the calling class. Just as in Delphi for .NET you can add multiple event handlers to an event.
An event has three main parts:
1. A method pointer property
2. The raising of the event
3. An event handler
1. A method pointer property.
Delphi and C# have a lot standard method pointer types. The most common Delphi method pointer type is the TNotifyEvent. In C# (or in .NET framework) this is the System.EventHandler.
You can use this methods, but you can also make your own.
Defining a method pointer type:
public delegate void OnSomething(object Sender, int Value);
In .NET you could, of course, store the parameters in a (derived) System.EventArgs object.
TOnSomething = procedure(Sender : TObject; Value : Integer) of Object;
They are just types that must be available for the object that uses them.
The class that wants to raise the event must have a public property for it:
public event OnSomething BeforeSomething;
property BeforeSomething : TOnSomething read FBeforeSomething write BeforeSomething;
(Where FBeforeSomething is a private field of the same type)
2. Raising the event
In this example the BeforeSomething event is raised. If the calling class has assigned the property to the (event) class this one can raise it.
public virtual void LetItHappen()
// The class should add a valid integer value for the event, here 10
if (OnSomething!= null) OnSomething(this, 10);
if Assigned(FOnSomething) then FOnSomething(Self, 10);
You must check if the property is assigned else you will get an access violation.
The code for C# and Delphi is amazingly similar. You can make it more similar if you like:
private bool Assigned(object AObject)
if (AObject != null)
the C# code then could be:
if Assigned(OnSomething) OnSomething(this, 10);
3. The eventhandler
In the calling object you should first make an event handler method:
(Suppose the calling is SomeObject : TSomeClass)
private void MyBeforeSomething(object Sender, int Value)
procedure TSomeClass.MyBeforeSomething(Sender : TObject; Value :
The last thing you should do now is assigning the property:
SomeObject.BeforeSomething += new OnSomething(MyBeforeSomething);
A new handler is added to list of handlers (or listners). You can remove them by using '-='
SomeObject.BeforeSomething := MyBeforeSometing;
In Delphi for .NET you can also add multiple handlers (listners) for an
event, using the Include en Exclude methods.
Events in C# are basically the same as in Delphi. C# must be Delphi's little brother, no doubt about that.
More information on events in C# can be found on MSDN here.
Using an image as your UIBarButtonItem in your navigationcontroller bar can only be achieved by using a common UIButton as the BarButtonItem...
Delphi 2009 has support for generics, and has 'built in' generic types like TList, TArrays etc. If you want to use them you must add...
A new generic type in Delphi 2009 is TDictionary . TDictionary offers a way to store values based on a key into a list. TDictionary is decla...
In ASP.NET it is easy to set the prefered authentication method in the web.config file. For external websites this is set mostly to Forms ... | <urn:uuid:dfa8addc-43ae-4f77-b5c4-1681f3121d15> | 3.703125 | 818 | Tutorial | Software Dev. | 50.569688 | 95,636,973 |
A study led by SISSA and published in Nature Nanotechnology reports for the first time the phenomenon of ion trapping by graphene carpets and its effect on the communication between neurons. The researchers have observed ...
Superconductors contain tiny tornadoes of supercurrent, called vortex filaments, that create resistance when they move. This affects the way superconductors carry a current.
What does the word "nanotechnology" conjure up for you?
When it comes to matching simplicity with staggering creative potential, DNA may hold the prize. Built from an alphabet of just four nucleic acids, DNA provides the floorplan from which all earthly life is constructed.
DNA has an important job—it tells your cells which proteins to make. Now, a research team at the University of Delaware has developed technology to program strands of DNA into switches that turn proteins on and off.
For the past few decades, scientists have been inspired by the blueprint of life, DNA, as the shape of things to come for nanotechnology.
The green sulfur bacterium makes its home in the chilly waters of the Black Sea. To eke out its lonely existence, this life form scavenges energy from the feeble sunlight available to it at a depth of over 250 feet.
Halonium ions used in this study, are well-known reaction intermediates and halogenating reagents in synthesis, but now they have been used as robust and stable structural units in molecular nanotechnology.
World-renowned nanoscientists and chemists Chad Mirkin, the Director of the International Institute for Nanotechnology (IIN) at Northwestern University, and Teri Odom, the IIN's Associate Director, sit down to discuss the ...
A team of scientists from the University of Chicago designed a way to use microscopic capsules made out of DNA to deliver a payload of tiny molecules directly into a cell. The technique, detailed Aug. 21 in Nature Nanotechnology, ... | <urn:uuid:f8296d4f-ec4f-4587-a51f-16faf943ba27> | 2.84375 | 394 | Content Listing | Science & Tech. | 39.336969 | 95,637,008 |
UCLA biologists reported last year on the evolution of 129 primate faces in species from Central and South America. This research team now reports on the faces of 139 Old World African and Asian primate species that have been diversifying over some 25 million years.
With these Old World monkeys and apes, the species that are more social have more complex facial patterns, the biologists found. Species that have smaller group sizes tend to have simpler faces with fewer colors, perhaps because the presence of more color patches in the face results in greater potential for facial variation across individuals within species. This variation could aid in identification, which may be a more difficult task in larger groups.
Species that live in the same habitat with other closely related species tend to have more complex facial patterns, suggesting that complex faces may also aid in species recognition, the life scientists found.
"Humans are crazy for Facebook, but our research suggests that primates have been relying on the face to tell friends from competitors for the last 50 million years and that social pressures have guided the evolution of the enormous diversity of faces we see across the group today," said Michael Alfaro, an associate professor of ecology and evolutionary biology in the UCLA College of Letters and Science and senior author of the study.
"Faces are really important to how monkeys and apes can tell one another apart," he said. "We think the color patterns have to do both with the importance of telling individuals of your own species apart from closely related species and for social communication among members of the same species."
Most Old World monkeys and apes are social, and some species, like the mandrills, can live in groups with up to 800 members, said co-author Jessica Lynch Alfaro, an adjunct assistant professor in the UCLA Department of Anthropology and UCLA's Institute for Society and Genetics. At the other extreme are solitary species, like the orangutans. In most orangutan populations, adult males travel and sleep alone, and females are accompanied only by their young, she said. Some primates, like chimpanzees, have "fission–fusion societies," where they break up into small sub-groups and come together occasionally in very large communities. Others, like the hamadryas baboons, have tiered societies with harems, clans, bands and troops, she said.
"Our research suggests increasing group size puts more pressure on the evolution of coloration across different sub-regions of the face," Michael Alfaro said.
This allows members of a species to have "more communication avenues, a greater repertoire of facial vocabulary, which is advantageous if you're interacting with many members of your species," he said.
The research, federally funded by the National Science Foundation and supported through a postdoctoral fellowship from the UCLA Institute for Society and Genetics, was published Nov. 11 in the journal Nature Communications.
Lead study author Sharlene Santana used photographs of primate faces for her analysis and devised a new method to quantify the complex patterns of primate faces. She divided each face into several regions; classified the color of each part of the face, including the hair and skin; and assigned a score based on the total number of different colors across the facial regions. This numerical score is called the "facial complexity" score. The life scientists then studied how the complexity scores of primate faces were related to primates' social systems.
The habitat where species live presents many potential pressures that could have influenced the evolution of facial coloration. To assess how facial colors are related to physical environments, the researchers analyzed environmental variables such as geographic location, canopy density, rainfall and temperature. They also used statistical methods that took into account the evolutionary history and relationships among the primate groups to better understand the evolution of facial diversity and complexity.
While facial complexity was related to social variables, such as group size and the number of closely related species in the same habitat, facial pigmentation was best explained by ecological and spatial factors. Where a species lives is a good predictor of its degree of facial pigmentation — how light or dark the face is.
"Our map shows clearly the geographic trend in Africa of primate faces getting darker nearer to the equator and lighter as we move farther away from the equator," Lynch Alfaro said. "This is the same trend we see on an intra-species level for human skin pigmentation around the globe."
Species living in more tropical and more densely forested habitats also tend to have darker, more pigmented faces. But the complexity of facial color patterns is not related to habitat type.
"We found that for African primates, faces tend to be light or dark depending on how open or closed the habitat is and on how much light the habitat receives," Alfaro said. "We also found that no matter where you live, if your species has a large social group, then your face tends to be more complex. It will tend to be darker and more complex if you're in a closed habitat in a large social group, and it will tend to be lighter and more complex if you're in an open habitat with a large social group. Darkness or lightness is explained by geography and habitat type. Facial complexity is better explained by the size of your social group."
In their research on primates from Central and South America published last year, the scientists were surprised to find a different pattern. For these primates, species that lived in larger groups had more plain facial patterns.
"We expected to find similar trends across all primate radiations — that is, that the faces of highly social species would have more complex patterning," said Santana, who conducted the research as a postdoctoral fellow with the UCLA Department of Ecology and Evolutionary Biology and UCLA's Institute for Society and Genetics and who is now an assistant professor at the University of Washington and curator of mammals at the Burke Museum of Natural History and Culture. "We were surprised by the results in our original study on neotropical (Central and South American) primates."
In the new study, they did find the predicted trends, but they also found differences across primate groups — differences they said they found intriguing. Are primate groups using their faces differently?
"In the present study, great apes had significantly lower facial complexity compared to monkeys," Lynch Alfaro said. "This may be because apes are using their faces for highly complex facial expressions and these expressions would be obscured by more complex facial color patterns. There may be competing pressures for and against facial pattern complexity in large groups, and different lineages may solve this problem in different ways."
"Our research shows that being more or less social is a key explanation for the facial diversity that we see," Alfaro said. "Ecology is also important, such as camouflage and thermal regulation, but our research suggests that faces have evolved along with the diversity of social behaviors in primates, and that is the big cause of facial diversity."
Alfaro and his colleagues serve as "evolutionary detectives," asking what factors produced the patterns of species richness and diversity of traits.
"When evolutionary biologists see these striking patterns of richness, we want to understand the underlying causes," he said.
Human faces were not part of the analysis, although humans also belong to the "clade Catarrhini, which includes Old World monkeys and apes.
Andrew Noonan, a former UCLA undergraduate student who conducted research in Alfaros laboratory, was also a co-author of this research.
For more on the Alfaros' research, visit the Alfaro Lab website.
UCLA is California's largest university, with an enrollment of more than 40,000 undergraduate and graduate students. The UCLA College of Letters and Science and the university's 11 professional schools feature renowned faculty and offer 337 degree programs and majors. UCLA is a national and international leader in the breadth and quality of its academic, research, health care, cultural, continuing education and athletic programs. Seven alumni and six faculty have been awarded the Nobel Prize.
For more news, visit the UCLA Newsroom and follow us on Twitter.
Stuart Wolpert | 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:c03c198d-40c0-4364-8611-a396681e079b> | 3.625 | 2,288 | Content Listing | Science & Tech. | 34.628996 | 95,637,009 |
In research published in the Journal of Cell Biology, scientists from the RIKEN Brain Science Institute in Japan have made important steps toward understanding how dynein--a "molecular motor"--walks along tube-like structures in the cell to move cellular cargo from the outer structures toward the cell body of neurons. The action of this molecule is important for a number of cell functions including axonal transport and chromosome segregation, and its dysfunction is known to lead to a congenital developmental brain disorder known as lissencephaly.
Though cells may look like shapeless blobs of liquid encased in a membrane, in fact they have a complex skeleton-like structure, known as the cytoskeleton, made up of filaments called microtubules. Motor proteins, which include dynein and kinesin, can move along these tubules to transport cargo into and out of the center of the cell.
The motor proteins use an energy-currency molecule, ATP, to power their movements along the microtubules. The motor proteins hydrolyze ATP to ADP, and convert the released chemical energy to mechanical energy which is used for movement. The mechanism is quite well understood for kinesin, but in the case of dynein, it has been difficult to explain how communication takes place between the site of microtubule binding and the site of ATP hydrolysis, which are relatively far from each other, separated by a stalk.
In the new research, performed in collaboration with several other institutes including the University of Osaka, Waseda, and Hosei University, the RIKEN scientists used cryo electron microscopy--where molecules are cooled to very low temperatures in the microscope--and examined the structure of dynein on the microtubule.
They showed that two specific amino acid residues on the microtubule structure, R403 and E416, are key to turning on the switch that is critical for the activation of the dynein motor--demonstrating that when mutations in these sequences are present, the dynein fails to achieve directional movement on the microtubule, ending up simply moving back and forth in a random fashion.
This lends weight to the idea, that has been generally accepted, that the motion of molecular motors is basically driven by random, Brownian motion, and that motors are able to move in one direction thanks to subtle changes in the strength of bonds at the motor-microtubule interface.
Additionally, the group discovered that turning on the mechanical switch at the motor-microtubule interface leads to ATP hydrolysis. Their results altogether indicate that the subtle structural changes in the bonds at the interface are transmitted through a small change in the structure of the stalk--there are two coils that link the two binding regions, and a small shift in the configuration of the coils gives the cue for ATP hydrolysis at the ATP binding site.
Seiichi Uchimura, the first author of the paper, said, "We were able to clearly demonstrate that the dynein molecular motor is activated by a 'switch' that controls mutual interactions between dynein and the microtubule. This is important, as a mutation in the structure of the switch has been demonstrated to cause lissencephaly, a congenital disorder."
According to Etsuko Muto, who led the research team, "In the future, we hope that further understanding the interplay between dynein and microtubule, as this could pave the way for therapies for these conditions."
Jens Wilkinson | 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:006f0628-f7e6-4ea9-9e0b-f0a81c0417b7> | 3.453125 | 1,373 | Content Listing | Science & Tech. | 33.678313 | 95,637,010 |
Explanation: Reflection nebulas reflect light from a nearby star. Many small carbon grains in the nebula reflect the light. The blue color typical of reflection nebula is caused by blue light being more efficiently scattered by the carbon dust than red light. The brightness of the nebula is determined by the size and density of the reflecting grains, and by the color and brightness of the neighboring star(s). NGC 1435, pictured above, surrounds Merope (23 Tau), one of the brightest stars in the Pleiades (M45). The Pleiades nebulosity is caused by a chance encounter between an open cluster of stars and a molecular cloud. | <urn:uuid:af70cc63-9255-4a34-aaf7-0c9d840c390b> | 4 | 137 | Personal Blog | Science & Tech. | 52.906786 | 95,637,020 |
Overlapped I/O is an asynchronous I/O extension of the Windows APIs, which was introduced in Windows NT.
Utilizing overlapped I/O requires passing an OVERLAPPED structure to API functions that normally block, including Winsock WSASend() and WSARecv().
The requested operation is initiated by a function call which returns immediately, and is completed by the OS in the background.
The caller may optionally specify a Win32 event handle to be raised when the operation completes.
Alternatively, a program may receive notification of an event via an I/O completion port, which is the preferred method of receiving notification when used in symmetric multiprocessing environments or when handling I/O on a large number of sockets.
Overlapped I/O is particularly useful for sockets . It is not well supported in Windows 9x.
The Unix equivalent of overlapped I/O is the POSIX asynchronous I/O API (AIO).
Overlapped I/O 是Windows API的一个异步I/O操作的拓展.在Windows NT中被引入.
使用Overlapped I/O 需要传递一个 OVERLAPPED structure 到 创建socket 参数中,以及Winsock WSASend() and WSARecv() 函数中.
被OVERLAPPED struct 初始化的WSASend() and WSARecv() 函数调用时,会立刻返回.并且通过操作系统在背后完成.
函数调用者可以指定一个Win32 Event Handle 解决 I/O 操作完成时的事件.
Overlapped I/O 对于Socket特别有用途.但是在windows 9x中支持的不是很好.
在Unix系统中, The POSIX asychronous I/O (AIO) 和Overlapped I/O功能差不多.
小结: Overlapped I/O 实质上就是一种异步I/O模型,在Unix 系统中为AIO模型 | <urn:uuid:45f17f5d-b923-41d8-bdbb-b720bba1999a> | 2.703125 | 601 | Knowledge Article | Software Dev. | 44.739253 | 95,637,040 |
THUS SPOKE HTML
For many of us HTML as a language is expressed visually and often implicitly as graphical user interfaces (often dressed in fancy CSS threads). For others it is an aural and explicitly expressed language, one in which shape, color and decoration play little part, its meaning is conveyed by words and interaction behaviours.
Typical support patterns of HTML elements by screen readers:
- Identification of an element by role as the user moves through the content.
- Announcement of the text content of an element.
- Announcement of the start and end of an element.
- Change in voice as the content of an element is announced.
- Announcement of an elements accessible name and/or description
- Announcement of states and properties.
- Emission of a beep or other sound when an element with a particulat state or property receives virtual focus.
- Instructions on how to operate interactive elements such as form controls.
- Navigation of elements by keyboard and “quick access” lists of a particular elements, list items are linked to each instance of an element on the page.
Note: The combination of patterns supported varies from element to element and support for a particular element varies between screen reader software.
Example of aural UI of HTML heading elements
The h1-h6 (heading) elements are imbued with visual semantics due to their style, and placement in the context of other content, but styling is a weak semantic, as is placement alone, and there are no rules or best practices about maintaining any visual style to indicate a headings style is an expression of its role in document structure. In fact the whole point of CSS is to allow developers to modify the default styles of HTML elements.
But the aural semantics of a heading are explicit and robust, regardless of its style in the document a <h1> is a <h1>, is a <h1>… unless overidden with ARIA. This why there are a set of document conformence rules for use of ARIA in HTML, to guide and constrain developers use of ARIA, so as not to screw up the native semantics of HTML.
Aural UI of h1-h6 elements on a test page:
“text content of heading, Heading level 1″
“text content of heading, Heading level 2″
“text content of heading, Heading level 3″
“text content of heading, Heading level 4″
“text content of heading, Heading level 5″
“text content of heading, Heading level 6″
Example of navigation features for h1-h6 elements provided by a particular screen reader:
- List Headings INSERT+F6
- Next Heading H
- Prior Heading SHIFT+H
- First Heading ALT+INSERT+HOME
- Last Heading ALT+INSERT+END
- Next Heading at Level — number keys 1 through 6
- Prior Heading at Level SHIFT+1 through 6
- First Heading at Level ALT+CTRL+INSERT+1 through 6
- Last Heading at Level ALT+CTRL+INSERT+ SHIFT+1 through 6
If you would like to hear more; the Aural UI of the Elements of HTML is a work in progress that aims to document how aural user agents bring HTML to life for their users. Forks and pull requests welcome!
Originally published at www.paciellogroup.com. | <urn:uuid:bad8e82f-159b-4a7d-a5ac-5d8a25eabb21> | 3.65625 | 735 | Personal Blog | Software Dev. | 44.596923 | 95,637,042 |
Is there any difference between BOOL and Boolean in Objective-C?
I know BOOL is actually a typedef of signed char.
But what about Boolean?
I am confused of bool, Boolean and BOOL…. Q Q
- Can't build an app for distribution after joining existing enterprise developer program
- What's the difference between AnyObject and UIbutton as sender?
- Has anyone experienced crashes when using ALAssetsLibrary in a background thread?
- Using the UIDocumentPickerViewController, is it possible to show a default service (Dropbox, Google Drive, etc) on first open like in Slack?
- Alternative to deprecated AudioSessionGetProperty, for iOS 7
- ios capturing image using AVFramework
Solutions Collect From Internet About “Is there any difference between BOOL and Boolean in Objective-C?”
Boolean is an old Carbon keyword (historic Mac type), defined as an
BOOL is an Objective-C type defined as
bool is a defined version of the
_Bool standard C type. It’s defined as an
- Adding a UIPanGestureRecognizer and a UISwipeGestureRecognizer to same view causes conflicts after setting requireGestureToFail
- NSCursor: “set” method has no effect
- how to play local video file?
- Xcode & Swift – Window without title bar but with close, minimize and resize buttons
- Where to initialize target in a UIButton? Particularly caring for IBDesignable
- Open app from SMS with my url scheme as a link
- Need to convert NSData to NSArray
- How to refresh Project Navigator content in Xcode?
- How to get iOS appStoreReceiptURL into Base 64 Encoded String?
- Can I use Objective-C blocks as properties?
- Delay when using instantiateViewControllerWithIdentifier but not performSegueWithIdentifier?
- MFMailComposeViewController throws an error only in iOS 9
- Let User Crop Photo in iOS App
- Adding Swift files to test target not fixing unit tests
- How to check a version of a CocoaPods framework | <urn:uuid:3639f937-2606-4aa2-9c9e-23483b5dbc6a> | 2.671875 | 466 | Q&A Forum | Software Dev. | 27.84075 | 95,637,054 |
Cumulative Flow Diagram (Burnup Chart) Scrum Tools Much as a Burndown Chart shows work remaining,…
Scrum GuideScrum has been used to develop complex products since the early 1990s. This paper describes how to use Scrum to build products. Scrum is not a process or a technique for building products; rather, it is a framework within which you can employ various processes and techniques. The role of Scrum is to surface the relative efficacy of your development practices so that you can improve upon them while providing a framework within which complex products can be developed.
Download the Tool/Template | <urn:uuid:7b563777-e500-4914-971e-385daa0af97d> | 2.5625 | 126 | Truncated | Software Dev. | 39.004659 | 95,637,092 |
Trapped Below Ground: The Importance of Circadian Rhythm
Thirty-three workers were rescued recently after being trapped under ground when a mine collapsed in Chile in August. The workers were trapped 2,300 feet beneath the surface for 69 days—a very, very long time to be without natural light!
While engineers worked on a rescue solution, rescuers above ground were able to rig systems to get required staples to the miners: food, vitamins, reading material, a portable music player (that was shuttled up and down to be charged). The trapped group was even able to watch a football game projected onto a cave wall. What couldn't be passed down, however, was sunlight. While there were some portable light sources available, being without natural light for such a long time poses many potential health hazards because our bodies depend on an awareness of natural light to keep our "internal clock" regulated.
This internal clock is related to "circadian rhythm" which tells our bodies when to "do" certain things each day. At the most basic level, our bodies are trained to sleep when it's dark and be up and about in the light. Almost all living things, even microbes, show evidence of circadian rhythm, and this rhythm controls a huge number of physical, mental, and behavioral processes, changes, and fluctuations, including things like body temperature, bowel movements, sleep, and the ability to stabilize one's emotional mood.
The trapped miners faced an extended period of circadian rhythm disruption, but this is an area of study that has impact for astronauts, airline pilots (who often fly across multiple time zones) and even workers who routinely work a night-shift, as well.
To begin exploring the presence and impact of circadian rhythms, take a look at these Science Buddies project ideas:
- Can Your Body Temperature Tell the Time of Day? Find Out with Human Circadian Cycles.: Chart the changes in temperature and reaction time throughout the course of a day in this human health project. (Difficulty: 6)
- Bioluminescence: Investigating Glow-in-the-Dark Dinoflagellates: Study the importance of a regular light-to-dark cycle on the bioluminescence of the marine dinoflagellate Pyrocystis lunula. (Difficulty: 7)
- Tick Tock, Tick Tock, Does Your Mouse Know the Time on the Clock?: Examine the activity of a rodent (or family pet) at various times of the day in this mammalian biology project. (Difficulty: 7)
You Might Also Enjoy these Previous Entries:
- Real-world Blood Typing and the Value of Blood Donation
- A Pet Science Project Success
- Laurel vs. Yanny and Student STEM
- Inspiring Students about STEM Careers and Robotics
- Celebrate Engineers Week with the Fluor Challenge
- Can Aerodynamic Suits Give U.S. Speed Skaters an Edge?
- Put a Heart Health Spin on Valentine's Day
- Classroom Science for Flu Season | <urn:uuid:91629eb0-35e6-478a-9e8f-090a236f2a6d> | 3.828125 | 624 | Personal Blog | Science & Tech. | 39.689153 | 95,637,098 |
Rotation Diffusion and Ortho-Para Conversion
In all solids near the melting temperature diffusion occurs due to thermally activated interchanges of neighboring particles. In ionic crystals, for example, this diffusion is responsible for the electrical conductivity of these crystals at high temperatures. In solid H2 and D2 the diffusion of J = 1 impurities just below the melting temperature has been observed through its effect on the NMR spectra.1, 2 This molecular motion decreases exponentially with decreasing temperature and is essentially frozen out a few degress below the melting point. The diffusion of J = 1 impurities in solid para-H2 has, however, been observed to persist down to temperatures on the order of 1 K.3 Since this low-temperature diffusion must be due to nonthermal effects of a quantum nature, it has been called quantum diffusion. In contrast to the hopping processes responsible for the diffusion, the diffusion itself is entirely classical, and we therefore prefer to use the term rotation diffusion which also agrees more closely with the fact that, in this process, the molecules do not interchange positions. The mechanism responsible for the diffusion is the conversion of ortho-para into para-ortho pairs and is due to the magnetic dipole-dipole interaction between the nuclear spins in neighboring molecules.4 This same interaction also gives rise to ordinary ortho-para conversion which changes the over-all ortho-para concentration ratio.
KeywordsRotation Diffusion Jump Frequency Solid Hydrogen Quantum Diffusion Energy Mismatch
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.
M. Bloom, Nuclear spin relaxation in hydrogen. III. The solid near the melting point, Physica
, 767–780 (1959).ADSCrossRefGoogle Scholar
R. F. Buzerak, M. Chan, and H. Meyer, NMR relaxation measurements in solid H2
at low ortho-H2
concentrations, J. Low Temp. Phys.
, 415–441 (1977).ADSCrossRefGoogle Scholar
L. I. Amstutz, J. R. Thompson, and H. Meyer, Observation of molecular motion in solid H2
below 4.2 K, Phys. Rev. Lett.
, 1175–1177 (1968).ADSCrossRefGoogle Scholar
R. Oyarzun and J. Van Kranendonk, Theory of quantum diffusion in solid hydrogen and deuterium. I. Calculation of the jump frequency, Can. J. Phys.
, 1494–1510 (1972).ADSCrossRefGoogle Scholar
K. Motizuki and T. Nagamiya, Theory of the ortho para conversion in solid hydrogen, J. Phys. Soc: (Japan)
,93–104 (1956).ADSCrossRefGoogle Scholar
A. J. Berlinsky and W. N. Hardy, Theory of ortho para conversion and its effect on the NMR spectrum of ordered solid ortho-hydrogen, Phys. Ret
, 5013–5027 (1973).ADSGoogle Scholar
R. J. Roberts and J. G. Daunt. Specific heats of solid hydrogen, solid deuterium, and solid mixtures of hydrogen and deuterium, J. Low Temp. Phys.
, 97–129 ( 1972).ADSCrossRefGoogle Scholar
D. Ramm and H. Meyer, Quantum diffusion in solid H2
. J. Low Temp. Phys.
, 173–186 (1980).ADSCrossRefGoogle Scholar
S. A. Boggs and H. L. Welsh, An infrared spectroscopic study of quantum diffusion in solid hydrogen, Can. J. Phys.
, 1910–1914 (1973).ADSCrossRefGoogle Scholar
B. J. Roffey, S. A. Boggs, and H. L. Welsh, Infrared studies of quantum diffusion in solid hydrogen, Can. J. Phys.
, 2451–2453 (1974).Google Scholar
W. N. Hardy, A. J. Berlinsky, and A. B. Harris, Microwave absorption of ortho-H2
pairs in solid hydrogen, Can. J. Phys.
, 1150–1179 (1977).ADSCrossRefGoogle Scholar
S. Washburn, R. Schweizer, and H. Meyer, NMR studies on single crystals of H2
. III. Dynamic effects. J. Low Temp. Phys.
, 187–205 (1980).ADSCrossRefGoogle Scholar
J. Van Kranendonk, Quantum diffusion of orthohydrogen pairs in solid parahydrogen, J. Low Temp. Phys.
, 689–699 (1980).ADSCrossRefGoogle Scholar
J. Van Kranendonk, Theory of the quantum diffusion of parahydrogen impurities in solid orthohydrogen. Phys. Rev.
, 4571–4584 (1980).ADSGoogle Scholar
I. F. Silvera, The solid molecular hydrogens in the molecular phase: Fundamentals and static properties, Rev. Mod. Phys.
, 393–452 (1980).ADSCrossRefGoogle Scholar
© Plenum Press, New York 1983 | <urn:uuid:2bbe9a3b-a102-43d1-8533-4a958e9149aa> | 2.578125 | 1,114 | Academic Writing | Science & Tech. | 65.61705 | 95,637,108 |
Just how realistic is it to believe that humans will someday find evidence of extraterrestrial life?
NASA's chief scientist recently predicted that we'd find signs of life beyond Earth within a decade or so, but a new study by researchers at Penn State -- one of the most exhaustive of its type -- isn't very encouraging.
After surveying tens of thousands of galaxies surrounding our own Milky Way galaxy, the scientists turned up no sign of advanced alien civilizations.
"These galaxies are billions of years old, which should have been plenty of time for them to have been filled with alien civilizations, if they exist," Dr. Jason T. Wright, an assistant professor of astronomy and astrophysics at the university's Center for Exoplanets and Habitable Worlds and one of the researchers, said in a written statement. "Either they don't exist, or they don't yet use enough energy for us to recognize them."
Turning up the heat. For the research, Wright and his colleagues analyzed a vast catalog of observations made in 2010 by NASA's Wide-field Infrared Survey Explorer (WISE) space telescope. The team looked at the heat emitted by the 100,000 "most promising" candidates of the all-sky catalog's nearly 100 million entries.
"The idea behind our research is that, if an entire galaxy had been colonized by an advanced spacefaring civilization, the energy produced by that civilization's technologies would be detectable in mid-infrared wavelengths -- exactly the radiation that the WISE satellite was designed to detect for other astronomical purposes," Wright said in the statement.
Time to give it up? Despite his negative findings, Wright said his study, published April 15 in the Astrophysical Journal Supplement Series, was "just the beginning," and that further research may yet turn up evidence of alien technology.
And other experts involved in the search for extraterrestrial intelligence (SETI) told The Huffington Post that they're far from discouraged.
Dr. Avi Loeb, a theoretical physicist at the Harvard-Smithsonian Center for Astrophysics in Cambridge, Mass., told HuffPost Science in an email that it's possible alien civilizations are hard to detect because they use much less energy than Dyson proposed.
"The limits reported in this study rule out the most extreme environmental impact possible for an extraterrestrial civilization that harvests a significant fraction of the starlight in its host galaxy," he said. "For comparison, our civilization processes only a thousandth of a trillionth of the energy output of the sun. Less visible civilizations are much more likely to exist, both in terms of the technological feasibility of energy harvesting as well as in terms of their energy needs."
Legendary astronomer Dr. Jill Tarter, the former director of the Center for SETI Research in Mountain View, Calif. and the astronomer on whom Jodie Foster's character in the 1997 film "Contact" was loosely based, agreed that efforts to find extraterrestrial life should continine.
"It's absolutely not time to stop," she told The Huffington Post in an email. "It's time to improve the sensitivity and specificity of these searches to be able to discriminate between signals produced by Mother Nature and those produced by engineers." | <urn:uuid:cc35a4cf-f9af-4e5b-a6ae-1760489e53cc> | 3.359375 | 650 | News Article | Science & Tech. | 35.188602 | 95,637,122 |
The complete larval development (eight zoeae and megalopa) of Periclimenes sagittifer (Norman, 1861) (Decapoda: Palaemonidae: Pontoniinae) from laboratory- reared material is described and illustrated. The mor- phology of the first larval stage is compared with previous larval descriptions of other species in the genus (P. agag, P. americanus, P. calmani, P. diversipes, P. grandis and P. pandionis). The importance of chemical settlement cues for late stage Periclimenes larvae is discussed.
Mendeley saves you time finding and organizing research
Choose a citation style from the tabs below | <urn:uuid:e4defad6-7c41-42b0-a362-5cd001eb472c> | 2.78125 | 149 | Academic Writing | Science & Tech. | 25.968669 | 95,637,123 |
The triple A syndrome is due to mutations in ALADIN, A novel member of the nuclear pore
Nuclear poly(A)-binding protein PABN1 is associated with RNA polymerase II during transcription and accompanies the released transcript to the nuclear pore
Recently, a group of researchers at Oxford University published a model for the structure of the nuclear pore
complex (NPC), the gatekeeper for the movement of molecules into and out of the nucleus (Alber et al.
The overall size of the CNH is too large to navigate the smaller (~40 nm dia) nuclear pore
For example, those proteins specific to the nuclear envelope and components of the nuclear pore
complexes, which allow the transport of large molecules to and from the nucleus, are cobbled together from protein domains specific to eubacteria and archaea, with various eukaryotic innovations.
Thus far, signal-mediated transport via pores has been demonstrated only for ultrafine gold particles of up to 39 nm in diameter, through the nuclear pore
complex in Xenopus oocytes, where transport velocities depended on particle size (Pante and Kann 2002).
Figure 1C shows a portion of a nucleus stained with antibodies to the nuclear pore
complex, followed by secondary antibodies that are conjugated to 0.
Beatty (1969); A large particle associated with the perimeter of the nuclear pore | <urn:uuid:94f6ae95-410b-4f8f-a011-ac290e91577b> | 2.828125 | 291 | Knowledge Article | Science & Tech. | 0.058333 | 95,637,131 |
I will try to find one.
I am still in the learning phase of SR and trying to get a grasp on it myself. Most of the math is still rather esoteric to me but hopefully not someday. Here is how I understand it today using a thought experiment.
There is one person on the surface of the Earth and another traveling in a spaceship near the speed of light at a constant velocity. When the spaceship traveler is perpendicular to the surface of the Earth where the other observer is, they synchronize their clocks and agree on the coordinate system they are going to use. Both of their clocks consist of two mirrors separated by 1/2 a light second in the Y direction (it is a large spaceship). The clocks send a light pulse from the bottom mirror to the top mirror where it is reflected and returns to the bottom mirror where a detector measures the incoming light pulse. This constitutes one second for each observer with their own clocks.
The spaceship is traveling with a velocity near the speed of light in the X direction relative to the Earth observer.
As the spaceship and the Earth are receding from each other let's say they have the ability to look at each other's clocks for a brief moment. From the perspective of each observer it appears that the other's clock is running slowly because each light pulse appears to take a longer path before it returns to the bottom mirror because the mirrors themselves appear to be moving along the X axis of relative motion.
So as each observer looks at the light clock of the other, they both come to the conclusion that the clocks of the other observer are running slowly. But in each of their own references frames, they will see their light clocks operating normally and counting off seconds.
For this thought experiment, let's assume that the size of the universe is small and has periodic boundaries so that the spaceship does not have to accelerate at all and comes back "around" to once again be perpendicular to the observer on the Earth after 10 light days, as measured by the spaceship. They compare their clocks again at the same point in space-time as before, and the clock in the spaceship has indeed recorded much less time than the observer on Earth. How is that possible?
The way I am (hopefully) seeing it, like the experts have posted, is that time is just another dimension. Like the spacial dimensions x,y, and z of familiar Cartesian coordinates we all know and love. Time can be measured in units of length by multiplying c (the speed of lights) by time. The Earth observer's change of position through space (orbiting around the Sun, the solar system orbiting around the galaxy) is negligible compared to the spaceship observer's change of position through space because the velocity of the spaceship dwarfs that of the Earth-solar system velocity. Here (I think) is the crux of the situation. Everyone is moving through space-time at the speed of light. The Earth observer is using most of his velocity to travel along the time axis and very little of the component velocity to travel through x, y, and z. So the Earth observer is moving very nearly to the speed of light along the time axis. The spaceship observer is traveling near the speed of light in the X direction so very little of his component velocity in traveling along the time axis. All the axis components of the velocity must add to c (the speed of light). So, you can either stay relativity still and travel through time quickly for your position in space-time, or you can travel about at velocities near the speed of light and come back to that same location in space-time without much time passing on your (spaceship) clock. You will be younger than the observer on Earth.
Hopefully that's close.
Thank you for the example laymanB. It does help some, I need to give it more thought.
After doing a little research on points of error in my understanding, revealed by others in this thread. It is clear to me that I lack a basic understanding of some of the terms and words I was throwing around. My apologies.
I joined and posted here hoping to resolve my confusion on this topic (and others).
My initial post on this thread was meant to put out what I thought was right about the topic, mostly so that what was wrong would be pointed out.
I plan on more study of time dilation and related topics. If I learn more, I will be back to discuss. Thanks to all for your "time" and input.
You're welcome. Just don't go using my example in any doctoral dissertation, I'm sure it is full of loose language and probably errors. It could also be flat wrong, we will let the experts weigh in.
I think the first place to start is learning Galilean invariance. You talked several times about being in an inertial state. I'm not sure what that is but I am assuming you mean an inertial frame of reference. An inertial frame of reference is a frame of reference in which Newton's laws are true. This means someplace where you can do an activity like juggling and everything will feel "normal" to your everyday experience like on the surface of the Earth, even though the surface of the Earth is not technically an inertial frame, it is close enough. Once you pick an inertial frame of reference, then any other frame moving with constant velocity relative to that frame is also inertial. Here is a good YouTube video from 1960.
This should give you a good idea of why the light path looks different in the clock example above. If you already understand this fairly well, then disregard it. Once you understand that the Einstein's second postulate states that the speed of light will be measured with the same speed in any reference frame, you can begin to work out the implications how people will disagree about time and distance measurements in their frames of reference and neither is more correct. I'm still learning too.
That's the wrong approach. You have to learn the math first. You cannot even talk about physic without this math. Of course, muons are accelerated due to gravity of the Earth, but you can safely neglect the effects of gravity of the Earth in HEP physics. It's way too weak to have an important impact on the particles.
Of course, there are exceptions to this rule, as the beautiful example of the measurement of the energy levels of neutrons in the gravitational potential of the Earth (note that this is in the Newtonian approximation) above a reflecting surface, but that's of course physics of ultra-low energetic neutrons. Here is a diploma thesis on the subject:
That is precisely the point. A measurement of time is a measurement of a kind of distance in spacetime, called the spacetime interval. Distance in normal Euclidean space is ##ds^2=dx^2+dy^2+dz^2## and the spacetime interval is ##ds^2=-dt^2+dx^2+dy^2+dz^2## so it is a distance in a spacetime with one timelike dimension and three spacelike dimensions.
The odometer analogy is intended to help you understand geometry in spacetime using mental experiences that you already have with geometry in space. You do yourself a great disservice by skipping it. It is one of the most powerful mental tools you have available.
Note that this assumption violates the principle of relativity. The geometry is called a four-torus. A four-torus may be locally flat, but there exists a preferred reference frame globally.
If a twin can be understood to be an AI and its history can be transferred electronically between closely passing ships, then the outgoing twin has his history transferred to an incoming ship without deceleration per se. Then when the incoming ship returns home, his history is transferred to a computer at home without deceleration per se.
That's a neat idea. Slightly less fancifully you could transfer the clock reading to an identical clock moving in the opposite direction and thus measure the proper time of the out and return journeys without a physical turn around.
How did the "outgoing" twin come be "outgoing"?
The initial outgoing ship was accelerated to speed before t=0 and then the AI was transferred from home to the passing ship at t=0
I like this way of subverting the acceleration requirement, but everything still works out. The AI "twin" that arrives on Earth still did not occupy a single inertial reference frame, whereas the one on Earth did. This is actually a good way of illustrating why the acceleration itself is not what is important, but the fact that one twin did not occupy a single inertial reference frame while the other did.
Or even more simply, that time was not accumulated over a single inertial path; this statement does not even need to mention frames.
Separate names with a comma. | <urn:uuid:9f96ff8b-7729-4216-810c-04229fca1b9a> | 3.453125 | 1,824 | Comment Section | Science & Tech. | 52.315604 | 95,637,137 |
Metals and Alloys
The structure of the valence bands of many metals is characterized by a great complexity and contains features that can be observed experimentally only by using spectroscopic instruments with a resolving power of the order of some tenths of an electron volt. At present, however, since most electron spectrometers have a resolution of about 0.6–0.9 eV, it is not yet possible to determine the detailed structure of the valence bands of most transition metals from their electron spectra. Thus the resolution of available instruments is completely inadequate for a determination of the accurate valence band structure of transition metals in which the density of the d states is high and their bandwidth is not large. As the atomic number increases, however, the valence band broadens. For gold, for example, it is possible to determine experimentally the whole fine structure previously predicted by relativistic band calculations.
KeywordsValence Band Fermi Level Photoelectron Spectrum Photoionization Cross Section Wannier Function
Unable to display preview. Download preview PDF. | <urn:uuid:ad7ed829-30dd-4154-9b3e-7b4ec0e3d081> | 3.34375 | 219 | Truncated | Science & Tech. | 24.082064 | 95,637,146 |
Bee grooming behaviour could help with microelectromechanical cleaning
A new study on the grooming habits of bees has given new physical insight into the process of pollination, and could have implications for future microelectromechanical systems (MEMS).
Researchers from the Georgia Institute of Technology in Atlanta, USA, and Kiel University in Germany, examined how pollenating insects that purposely cover themselves with millions of pollen particles get clean enough to fly.
Their study, published today in the journal Bioinspiration and Biomimetics, found that the key lies in the tiny hairs bees and other pollinators are covered in. They also found that the viscous fluid on the surface of pollen grains (or pollenkitt) plays an essential role in the process, by helping the pollen stick to the insect.
Co-author Professor David Hu from Georgia Tech said: “When it visits flowers over the course of a day, a typical worker bee can pick up five times its body weight in pollen on the hairs on its body. Of course, being completely covered in pollen particles will make sensing and controlling flight difficult.
“So how do the bees get themselves clean? We found their hairiness is the key not only to collecting the pollen but to getting clean as well. The hairs on the bees’ eyes, for example, are spaced so they suspend the pollen above the body, so it can be easily removed by the forelegs. In turn, the spacing of the hairs on the foreleg dictates the leg’s capacity to store pollen, and the amount it can remove with each swipe.”
The researchers developed an experiment to quantify the grooming performance of bees. They used a live honey bee coated in pollen and two cameras – one to film the bee’s cleaning motions, and the other to capture silhouettes of the pollen particles as they fell into a dish – to record the number of swipes the bee made to clean itself, and how much pollen it removed. They also looked at the motion the bees used, and the geometry and spacing of the hairs.
The team used two different types of pollen – commercially available bee pollen, and dandelion pollen – as well as corn starch to examine whether the size or type of the pollen grains made a difference to the rate of cleaning. By washing some of the pollen, they tested whether pollenkitt increased the pollen’s adhesive properties.
Professor Hu said: “Grain size has a major effect on whether pollen can be removed. We found bees could easily clean off around 15,000 particles of commercial pollen in three minutes, whereas they were still covered in corn starch after three minutes, as the grains are much smaller.
“We also found the presence of pollenkitt plays an important role in pollen accumulation. Honeybees accumulated half as many pollen grains when the pollenkitt was removed. We believe this study is the first to provide physical insight into the critical process of pollination.”
The team found that pollen type or initial pollen accumulation has no effect on grooming behaviour. However, they identified that the geometry of the hair on both the surface to be cleaned, and the one that does the cleaning, dictated their efficiency.
The hair spacing on the bee’s body is tuned to the particles they collect, to allow suspension and easy removal, while hair spacing on the grooming legs allows the transfer of particles from the body to the legs and determines the amount of pollen removed during each swipe.
Professor Hu said: “Furthermore, the methods used by pollinating insects for accumulating and removing micro-scale particles could influence designs for cleaning human-made surfaces, and generate brush-based surfaces with filtering and/or particle separating properties.
“With the emergence and growth of microelectromechanical systems, there are definitive implications for effective cleaning at the microscale.” | <urn:uuid:90847aaf-89c4-486f-b9c0-3b4adbadbb90> | 3.765625 | 791 | News Article | Science & Tech. | 35.35774 | 95,637,149 |
Differences In Benthic Metabolism, Nutrient Fluxes, And Denitrification In Caulerpa Taxifolia Communities Compared To Uninvaded Bare Sediment And Seagrass (zostera Capricorni) Habitats
- Amer Soc Limnology Oceanography
- Publication Type:
- Journal Article
- Limnology And Oceanography, 2011, 56 (5), pp. 1737 - 1750
- Issue Date:
Benthic metabolism, nutrient fluxes, and denitrification were measured in Caulerpa taxifolia communities that had recently invaded (between 2003 and 2008) bare sediments following the loss of Zostera capricorni (prior to 2003), and in adjacent Z. capricorni communities and bare sediments, to determine the likely changes in ecosystem function following C. taxifolia colonization. Areas colonized by C. taxifolia had higher gross primary production (GPP), net primary production (NPP), and dark benthic N2 effluxes than adjacent bare sediments, but lower dark benthic NH z 4 effluxes. C. taxifolia invasion of bare sediments had a beneficial role in removing excess nitrogen from the system through enhanced denitrification. In contrast, areas occupied by C. taxifolia had similar GPP and NPP relative to Z. capricorni beds and similar benthic N2 and NH z 4 effluxes. Thus, C. taxifolia appears to play a comparable role to Z. capricorni in terms of some ecosystem functions, although the degree of similarity is likely to be affected by the relative densities of the two macrophytes. However, replacement of Z. capricorni communities by C. taxifolia appears to significantly alter the quantity and quality (higher ratio) of benthic dissolved organic carbon and dissolved organic nitrogen fluxes.
Please use this identifier to cite or link to this item: | <urn:uuid:40de00e1-5b1e-425a-b0f9-c36e3dee4ed0> | 2.5625 | 412 | Academic Writing | Science & Tech. | 21.517607 | 95,637,155 |
+44 1803 865913
By: Kunio Iwatsuki(Editor), Peter H Raven(Editor)
330 pages, 55 illustrations, tables
Evolution and Diversification of Land Plants is a modern approach to understanding the evolution and diversification of land plants. It consists of three sections – origin and diversification of primitive land plants: origin and diversification of angiosperms; speciation and mechanisms of diversification – each section corresponding to a major area of plant evolution. In each case, data from molecular, morphological, and palaeontological approaches are presented, backed by recent progress and new findings, together with proposals for future research. A guide to the latest in plant systematics, heightening awareness of prospective future problems.
- Charting Diversity in Early Land Plants
- Morphological Diversity and Evolution of Vegetative Organs in Pteridophytes
- RNA Editing in Land Plants
- Phylogenetic Reconstruction of Some Conifer Families
- Evolutionary Biology of Flowers
- Fossil History of Magnoliid Angiosperms
- Molecular Phylogenetic Relationships Among Angiosperms
- Based on rbcL and 18S rDNA Sequences
- Evolution of MADS Gene Family in Plants
- Palynological Approaches to the Origin and Early Diversification of Angiosperms Chromosomal Evolution of Angiosperms
- Mating Systems and Evolution in Flowering Plants
- Plant Speciation on Oceanic Islands
- Speciation and Morphological Evolution in Rheophytes
There are currently no reviews for this book. Be the first to review this book!
Your orders support book donation projects
I don't know how you got a book printed 26 years ago in the conditions that I received it (like new) but you do it! ABSOLUTELY AWESOME!
Search and browse over 110,000 wildlife and science products
Multi-currency. Secure worldwide shipping
Wildlife, science and conservation since 1985 | <urn:uuid:a5610d09-90c6-4441-8762-fc0957cca13a> | 2.96875 | 411 | Product Page | Science & Tech. | 3.243711 | 95,637,160 |
Since heat flow in a large ice sheet is very slow, the borehole temperature is another indicator of temperature in the past, and these sources of information can be combined to find the climate model that best fits all the available data.Impurities in ice cores may depend on location; for example, coastal areas are more likely to include material of marine origin, such as sea salt ions.
Radioactive elements, either of natural origin or created by nuclear testing, can be used to date the layers of ice in the cores.
Both the physical properties of the ice itself and material trapped in the ice can be used to reconstruct information about climate over the age range of the core.
The ratio of oxygen and hydrogen isotopes in the ice provides information about ancient temperatures; and the air trapped in tiny bubbles in the ice can be analyzed to determine the level of atmospheric gases such as carbon dioxide.
Long ago, Ask a Mathematician / Ask a Physicist was two guys sitting around in the desert talking to strangers about whatever came to mind.
It’s been a while, but we’re heading back to Burning Man for more of the same! | <urn:uuid:197ccf68-97da-4bd7-be93-393a2d9f97ea> | 3.765625 | 235 | Personal Blog | Science & Tech. | 27.430299 | 95,637,177 |
The two Norwegian scientists could hardly believe their eyes on a dive on the far west of the coast of Spitzbergen in autumn 2004.
Right in front of NTNU Professor Geir Johnsen’s underwater camera a sensation was waiting for him: a colony of mussels had managed to attach itself to Sagaskjæret – the Saga Skerry – in Isfjorden.
Not since the early Middle Ages, when the climate enabled the Vikings to settle Iceland, Greenland and Newfoundland, have mussels established themselves as far north as Svalbard.
For mussels to survive they need temperatures well above those that have been normal in Norwegian arctic waters for the past thousand years. These shells were at least a year old, which means that they had survived at least one winter on the skerry, a fact that impressed the scientists even more than the find itself.
The discovery soon found its way into the columns of the local weekly “Svalbardposten”, then to international web-sites and news agencies. Journalists tended to present the return of the mussels as evidence of global climate change.
According to biology professor Geir Johnsen, however, the find in itself has no such significance.
“If we had found mussels on Svalbard for ten years in a row, it would have been different,” he says. But in the summer of 2005 the scientists found no mussels on Sagaskjæret. It remains to be seen whether they will find any this year.
Changing sea temperatures
Johnsen and his colleagues at the Svalbard University Centre, the University of Tromsø and SINTEF Fisheries and Aquaculture published their theories about the mussel find last autumn.
Referring to satellite and oceanographic measurements, they concluded that the return of the shellfish is due to oscillations in the temperature of the sea, given that the North-Atlantic Current transported unusually large volumes of water northwards in 2002 and 2003 and that this led to higher than normal surface temperatures west of Svalbard. In the summer of 2004, the water turned colder again.
The oceanographic measurements also showed that warm, highly saline Atlantic water found its way into Isfjorden in 2002 and 2003. The water was driven into the fjord by high northerly winds – such warm water is another prerequisite for the growth of the shellfish on Sagaskjæret.
Migration route recreated
Transportation of larvae from the coast of Norway by the North Atlantic Current is the only possible solution to the mystery of where these mussels came from. In Trondheim, SINTEF’s Dag Slagstad was ready to help his colleagues with the aid of a mathematical model of the ocean. Slagstad carried out simulations that showed that in the summer of 2002, mussel larvae drifting from the Vesterålen area would have managed to reach Svalbard in 60 days as “hitchhikers” on the current.
“This is at the very limit of the time that the larvae would have needed before they had to attach themselves to rocks. But some of them have obviously survived the trip,” says Professor Johnsen, who points out that the rare find is yet more evidence that biology is a finely tuned instrument.
“This find shows just how rapidly biological changes can take place when the external environment changes.”
Aase Dragland | alfa
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:38ef1c58-0383-4e07-9ab6-00b19399c0ca> | 3.796875 | 1,313 | Content Listing | Science & Tech. | 43.058965 | 95,637,188 |
In this study we investigate the geograph- ic distribution, genetic diversity, and phylogenetic relationships of an endangered tick, Amblyomma sphenodonti (Family Ixodidae). Amblyomma sphen- odonti and its host, the tuatara (Sphenodon), are found only on small offshore islands around New Zealand. Our results show that Amblyomma sphen- odonti has a more severely restricted geographic dis- tribution than its host, as it was found on only eight of 28 islands (four out of 12 island groups) where tuatara still live. The prevalence of A. sphenodonti is likely to have been affected by low host density and fluctuations in host population size as tuatara popula- tions became isolated on offshore islands. Analysis of A. sphenodonti cytochrome oxidase 1 (CO1) sequences indicated a lack of gene flow between islands, with fixed differences in CO1 sequences be- tween islands, but almost no genetic diversity within island populations. A similar phylogenetic pattern to that observed in tuatara mtDNA was observed, indicating co-evolution of two species, at least since the Pleistocene. Phylogenetic analysis using 18S rRNA sequences suggest that A. sphenodonti is not closely related to other Amblyomma species, and that a separate genus for this species may be warranted. However, data from other ixodid ticks are required before the distinctiveness of A. sphenodonti can be confirmed and the phylogenetic relationships among ixodid ticks fully understood.
Mendeley saves you time finding and organizing research
Choose a citation style from the tabs below | <urn:uuid:79b6a605-c118-4a16-a316-a087ad983401> | 2.953125 | 358 | Academic Writing | Science & Tech. | 17.945712 | 95,637,258 |
The GNU C Library Reference Manual
by Sandra Loosemore, at al.
Publisher: Free Software Foundation, Inc. 2007
Number of pages: 1001
The GNU C library, described in this document, defines all of the library functions that are specified by the ISO C standard, as well as additional features specific to POSIX and other derivatives of the Unix operating system, and extensions specific to the GNU system. The purpose of this manual is to tell you how to use the facilities of the GNU library.
Home page url
Download or read it online for free here:
by Zed A. Shaw - LCodeTHW
A clear and direct introduction to modern C programming. The purpose of this book is to get you strong enough in C that you'll be able to write your own software in it, or modify someone else's code. The text is not for beginners.
by Mark Burgess, Ron Hale-Evans - Free Software Foundation
This book is a tutorial for the computer programming language C. You should have some basic computer literacy: to be able to run a program, edit a text file, etc. The tutorial introduces basic ideas in a logical order and progresses steadily.
by Tim Bailey - University of Sydney
This textbook is a thorough introduction to the C programming language, with an emphasis on software design and code organisation. The author shows how to apply the language features to build scalable modular software systems.
by Jens Gustedt - ICube
The book introduces you to the very basics of programming with C, details most principal concepts and features such as control structures, data types, operators and functions, fully explains pointers, performance, reentrancy, atomicity, threads, etc. | <urn:uuid:194243df-d13a-4ac3-afd7-fbaee74d8989> | 3.03125 | 350 | Content Listing | Software Dev. | 41.374883 | 95,637,281 |
Aquatic Invertebrate Monitoring at Tallgrass Prairie National Preserve
Scientists use established methods to track aquatic invertebrates and assess stream water quality conditions. Aquatic invertebrates can include insect larvae, worms, crayfish, snails, and other animals without backbones. Many invertebrates live in a stream for several months, which exposes them to changing water quality conditions over time. When scientists monitor aquatic invertebrates, they can find out what species are present and their tolerance level to pollution and disturbances. Some species can live in poor water quality conditions, while others need cleaner conditions. Aquatic invertebrate communities can serve as the "canary in the coal mine" for water quality of a stream.
Since 2009, water quality, habitat, and aquatic insect communities indicate these streams may be mildly disturbed. The watershed of Fox Creek is impacted by several known human disturbances. However, several intolerant species were found in the streams. Both streams may also have natural seasonal stressors affecting stream quality. More monitoring may allow insight into trends occurring in the streams. Promoting conservation in the watershed also helps. | <urn:uuid:d4c0581e-d8ca-4315-8c02-86f086eaf4c1> | 3.78125 | 228 | Knowledge Article | Science & Tech. | 18.541638 | 95,637,290 |
An ecological system has a richly detailed budget of inputs and outputs of energy and matter. Because of the lack of precise information about these relationships and the internal functions that maintain the ecosystem, it is often difficult to assess the impact of human activities on the biosphere. As a result, land-use planners often cannot take into account or even foresee the full range of consequences a project may have. Without full information, the traditional practice in the management of land resources has been to emphasize strategies that maximize the output of some desirable product or service and give little or no thought to the secondary effects. As a result one sees such ecological confusion as an all-out effort to increase food production while natural food chains become increasingly contaminated with pesticides and runoff and seepage waters carry increasing burdens of pollutants from fertilizers and farm wastes. Forests are cut with inadequate perception of the effects on regional water supplies, wildlife, recreation, and esthetic values, and wetlands are converted to commercial use with little concern over important hydrologic, biologic, esthetic, and commercial values lost in the conversion.
KeywordsSecondary Mineral Northern Hardwood Fagus Grandifolia Experimental Watershed Tsuga Canadensis
Unable to display preview. Download preview PDF. | <urn:uuid:547d1e75-fee5-460f-83bc-7511771c7422> | 3.53125 | 250 | Truncated | Science & Tech. | 9.445352 | 95,637,302 |
create_module man page
create_module — create a loadable module entry
#include <linux/module.h> caddr_t create_module(const char *name, size_t size);
Note: No declaration of this system call is provided in glibc headers; see Notes.
Note: This system call is present only in kernels before Linux 2.6.
create_module() attempts to create a loadable module entry and reserve the kernel memory that will be needed to hold the module. This system call requires privilege.
On success, returns the kernel address at which the module will reside. On error, -1 is returned and errno is set appropriately.
A module by that name already exists.
name is outside the program's accessible address space.
The requested size is too small even for the module header information.
The kernel could not allocate a contiguous block of memory large enough for the module.
create_module() is not supported in this version of the kernel (e.g., the kernel is version 2.6 or later).
The caller was not privileged (did not have the CAP_SYS_MODULE capability).
This system call is present on Linux only up until kernel 2.4; it was removed in Linux 2.6.
create_module() is Linux-specific.
This obsolete system call is not supported by glibc. No declaration is provided in glibc headers, but, through a quirk of history, glibc versions before 2.23 did export an ABI for this system call. Therefore, in order to employ this system call, it was sufficient to manually declare the interface in your code; alternatively, you could invoke the system call using syscall(2).
delete_module(2), init_module(2), query_module(2)
This page is part of release 4.16 of the Linux man-pages project. A description of the project, information about reporting bugs, and the latest version of this page, can be found at https://www.kernel.org/doc/man-pages/.
delete_module(2), get_kernel_syms(2), init_module(2), query_module(2), syscalls(2), systemd.exec(5), unimplemented(2). | <urn:uuid:486698f7-b85e-4091-aefe-8b1621b75b3e> | 3.234375 | 485 | Documentation | Software Dev. | 49.793835 | 95,637,307 |
Insect order that comprises over 100,000 species, including the bees, wasps, and ants. Representatives may be social or solitary, free or parasitic.
They are insects with two pairs of wings, the forewings and hindwings being interlocked by means of hooklets. The wing venation is often reduced and the hindwings are usually smaller. The abdomen is usually constricted forming a ‘waist’. An ovipositor (egg-laying organ) is always present and modified for piercing, sawing or stinging. Metamorphosis is complete, and the larvae are usually without legs.
Hypermetamorphosis (in which the larva passes through several distinct forms) is not uncommon, especially in the parasitic species. Pupae are usually in a cocoon. with a great range of specialization of form. Parthenogenesis is frequent, in some cases giving rise only to males but in others producing females as well.
Suborder Symphyta consists of the more primitive hymenopterans. The waist is not present and the ovipositor is adapted for sawing or boring. Parasitism is rare. Most species have larvae associated with vegetation and three families contain members of importance to forestry and agriculture: the Siricidae (wood wasps and horn tails) have larvae that burrow into trees; the Diprionidae (conifer sawflies) cause defoliation of pine trees; and the Cephidae (stem sawflies), contain species that damage wheat crops.
Suborder Apocrita contains the majority of Hymenoptera with the typical ‘waisted’ appearance. There are a large number of parasitic families, all with the ovipositor adapted for piercing. Several families produce galls on plants. The Cynipidae, for instance, produce the familiar oak galls and also those on roses. Most are parasitic on other insect eggs, larvae, or pupae, and several are used for biological control of pests. The families are grouped in the superfamilies Trigonaloidea, Ichneumonoidea, including ichneumon flies, Evanioidea, Cynipoidea, including gall wasps, and Chalcidoidea. Most are small insects. The two superfamilies Proctotrupoidea and Bethyloidea also contain many species that are parasitic on other insects or form galls.
The other members of Apocrita have the ovipositor adapted for stinging, and are mainly colonial insects more generally recognized as bees, ants, and wasps. The superfamily Scolioidea contains primitive members of this group, sexual dimorphism is common and some species are parasites of bees and other insects.
The ants form superfamily Formicoidea of suborder Apocrita. They are generally treated as a single family, Formicidae. There are some 8,000 species. They are all social, with distinct castes.
The superfamily Pompiloidea contains solitary wasps, which usually build simple subterranean nests, and are parasitic on spiders. The paralysed spiders are stored in the nests for the young to feed on. The superfamily Vespoidea contains only one family, Vespidae, the true wasps. They may be either solitary or social.
Hymenoptera is in subclass Pterygota, class Insecta, phylum Arthropoda.
A large worldwide order of insects (over 100 000 species) including the ants, sawflies, ichneumons, wasps, and bees. Many species show a high...
common name for insects of several families of the order Hymenoptera, which also includes the ants, wasps, and bees. Sawflies are named for the two s
Small parasitic wasp closely related to the ichneumon flies, but differing from them mainly by having fewer wing veins. Braconids chiefly parasitize | <urn:uuid:ffc50747-13f6-4aa7-b437-5b5353de4883> | 3.9375 | 817 | Knowledge Article | Science & Tech. | 28.952009 | 95,637,325 |
Magnetic ratchet effects in a two-dimensional electron gas
- 59 Downloads
The effect of the magnetic field on the generation of an electric current in a two-dimensional electronic ratchet is theoretically studied. Mechanisms of the formation of magnetically induced photocurrent are proposed for a structure with a two-dimensional electron gas (quantum well, graphene, or topological insulator) with a lateral asymmetric superlattice consisting of metallic strips on the external surface of the structure. The ratchet with the spatially oscillating magnetic field generated by the ferromagnetic lattice, as well as the nonmagnetic ratchet placed in the uniform magnetic field both classically weak and strong quantizing, is considered. It is established that the ratio of the amplitude of the magnetic oscillations of photocurrent to the ratchet photocurrent in zero field can exceed two orders of magnitude.
Unable to display preview. Download preview PDF.
- 25.N. H. Lindner, A. Farrell, E. Lustig, F. von Oppen, and G. Refael, arXiv:1403.0010v2.Google Scholar
- 28.V. F. Gantmakher and I. B. Levinson, Carrier Scattering in Metals and Semiconductors (Nauka, Moscow, 1984; North-Holland, Amsterdam, 1987).Google Scholar | <urn:uuid:c432d6e6-2285-48da-b4ce-5610590b018f> | 2.5625 | 288 | Academic Writing | Science & Tech. | 39.776449 | 95,637,334 |
To demonstrate how to create a Web Form using Visual C#Learning Objectives
- Page navigation techniques - select the steps to enable a control to post back data to the server.
- Using ASP.NET intrinsic objects - use the request and response objects to intercept communication between a client and the server.
- Handling client actions - enable an ASP.NET page to handle client actions.
- Error handling in web applications - configure an ASP.NET application to catch exceptions and errors.
- Handling an error in a web application - handle errors that occur in a web application. | <urn:uuid:6b1c0fa2-2982-4b64-bd09-5d5fd35e4719> | 2.875 | 117 | Tutorial | Software Dev. | 46.192935 | 95,637,339 |
South Dakota ecologist earns National Wetlands Research Award
Wetlands may be the least understood ecosystem, but their value is immense, according to Distinguished Professor W. Carter Johnson of the South Dakota State University Department of Natural Resource Management. “Anything that affects them will have a big impact on the landscape.”
For more than 40 years, the ecologist has studied wetlands along rivers and in the prairie pothole region that extends from Canada through the Dakotas to Iowa. In recognition of his contributions to wetlands conservation, Johnson received the National Wetlands Award for Science Research from the Environmental Law Institute.
Since 1989, the National Wetlands Awards program has honored individuals who have demonstrated extraordinary commitment to our nation’s wetlands.
Understanding importance of wetlands
Through his wetlands research, Johnson has sought to help people understand their importance. “They have so much biodiversity and importance to the health of the landscape,” he noted, citing wetlands teaming with birds, amphibians and beneficial insects. In addition, wetlands retain floodwaters and filter water naturally.
South Dakota has a unique legacy in its mixture of lakes, wetlands and grasslands. ”It’s an incredibly beautiful and productive landscape and we haven’t treated it very well,” Johnson said.
Most of the river or riparian wetlands along the Missouri River were lost when the reservoirs were established, according to Johnson. He estimated that 80 percent of the riparian wetlands have been destroyed. The only sizable remnants in South Dakota occur below Gavins Point and Fort Randall Dams. These reaches “retain much of their original biodiversity observed by Lewis and Clark,” he explained.
For his dissertation in the early 70s he studied the forests along the river. Two years ago, he looked at what has changed over the last 40 years. “The cottonwood is on the way out,” he noted, because they “require floods and new sandbars to regenerate.” American elm is mostly gone from Dutch elm disease and ash trees are being threatened by the emerald ash borer.
Restoring tall prairie grasses
Seven years ago, Johnson became one of the founders of the EcoSun Prairie Farms to demonstrate the viability of a “working grass farm,” as a means of restoring tall grass prairie and pothole wetlands. He and his cohorts formed the nonprofit organization and leased a section of land near Colman, where they began planting blue stem, prairie cord grass and other perennial species native to the area on retired cropland.
The farm generates income from three main sources—forage hay, native plant seed and, more recently, grass-fed beef, he explained. The native grasses require less input than rowcrops, while resulting in less erosion, better soil and water quality and more wildlife.
During the dry summer of 2012, he pointed out, “the grass farm didn’t show drought.” The plants were a bit shorter, but “nothing died and it all came back the next year.” A recent analysis showed a net yearly farm profit of $60,000, and the highest income levels came from wetland acres.
“It’s a different way of farming,” Johnson admitted, but one that farmers who own 400 to 600 acres might want to consider. “I hope we can get it worked onto other farms.”
About South Dakota State University
Founded in 1881, South Dakota State University is the state’s Morrill Act land-grant institution as well as its largest, most comprehensive school of higher education. SDSU confers degrees from eight different colleges representing more than 175 majors, minors and specializations. The institution also offers 29 master’s degree programs, 13 Ph.D. and two professional programs.
The work of the university is carried out on a residential campus in Brookings, at sites in Sioux Falls, Pierre and Rapid City, and through Cooperative Extension offices and Agricultural Experiment Station research sites across the state.
Christie Delfanian | newswise
Upcycling of PET Bottles: New Ideas for Resource Cycles in Germany
25.06.2018 | Fraunhofer-Institut für Betriebsfestigkeit und Systemzuverlässigkeit LBF
Dry landscapes can increase disease transmission
20.06.2018 | Forschungsverbund Berlin e.V.
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
16.07.2018 | Physics and Astronomy
16.07.2018 | Life Sciences
16.07.2018 | Earth Sciences | <urn:uuid:04d4f3a4-4f9f-46f4-9bb2-2aacbd60d623> | 3.5 | 1,506 | Content Listing | Science & Tech. | 41.976154 | 95,637,352 |
Sign In / Sign Out
- ASU Home
- My ASU
- Colleges and Schools
- Map and Locations
Adaptation: a structure or behavior that helps an organism survive and reproduce.
Atmosphere: the thin layer of gases surrounding the planet (Earth's atmosphere)......more
Carbon dioxide: a chemical compound (a gas) that has two oxygen atoms and one carbon atom (CO2); carbon dioxide is a greenhouse gas... more
Climate: the weather patterns in a region over long periods of time.
Greenhouse effect: warming temperatures caused by the sun's energy becoming trapped.
Greenhouse gas: a gas that absorbs heat from the sun and thereby prevents some of the sun's energy from escaping back into outer space... more
Precipitation: water that falls from the atmosphere, whether as rain, snow, or another form.
Weather: short-term conditions of the atmosphere.
People are talking about it all over the globe. In some places, storms are more frequent, in others, temperatures are changing and droughts are longer. So what’s going on with all this wacky weather?
In today’s world, climate change is a popular topic, as it stands to affect the entire globe, including many of the plants and animals that we depend on to live. But what exactly does this crazy climate mean? What is causing it and why should we care? To understand the changes in Earth’s climate, we first need to look at how climate is different from weather.
Weather refers to the short-term conditions of the Earth’s atmosphere. When a news reporter talks about the amount of precipitation that fell yesterday or how hot or cold it is today, they are talking about the weather. These short-term changes happen from day to day and across seasons. For example, some days it is sunny and warm and we can play outside. Other days it is rainy and cold and we have to stay inside.
Climate happens over much longer time periods. If we took the average of all the weather for 30 years, then we would have the climate. It describes what we would expect the weather to be. For instance, we expect the climate of deserts to be warm and dry and the artic to be cold and snowy.
When someone talks about climate, they are not talking about a single weather event like a really hot day or a strong storm. They are talking about the long-term average conditions.
Here’s a popular way to remember the difference between climate and weather:
In areas with a very wet climate, like the Pacific Northwest, people are likely to own an umbrella because it is often rainy there. However if there is no chance for rain in the weather report, they may not take it with them for the day.
Around the world, the climate is changing. Temperatures are getting warmer and these changes are causing some places to get more or less rain than usual. Scientists know this is happening from studying Earth’s climates from over a million years ago. By studying these historical climates, they have found that Earth’s climate has changed many times and these changes are related to the amount of special gases in the atmosphere, called greenhouse gases (GHGs).
Greenhouses gases in the atmosphere work just like the glass of a greenhouse ceiling. The temperature inside a greenhouse is usually warmer than what it is outside. This warmth is from the sun’s energy passing through the glass but not escaping back outside. Inside greenhouses plants can still grow even when temperatures outside are cold.
If you’ve never been in a greenhouse, think of getting in a car during a warm, sunny day. You might remember that it was a lot hotter inside the car than it was outside. Greenhouse gases in our atmosphere work just like the glass in the car. They let the sun’s energy pass through but do not let it pass back to outer space. This is called the greenhouse effect. It happens because lots of energy from the sun reaches Earth, but not all of that energy can leave.
Some of this energy is trapped by the GHGs. How hot or cold the climate gets on Earth depends on the amount of GHGs in our atmosphere. If there were no GHGs in our atmosphere, Earth would be too cold for us. If there were too much of these gases, Earth would be too hot.
Today, lots of people are trying to understand how and why climate is changing. Because plants and animals are adapted to the places where they live, changes in climate could make them unable to survive in certain places. If the plants and animals cannot move to another area or adapt to the new climate, then they may become extinct. Extinction means all members of a species disappear forever. If a species goes extinct, humans may lose the benefits it provides.
The amount of GHGs in our atmosphere and the climate has changed a lot in the past. These changes happened way before there were people and some of the changes caused species to go extinct. Many changes were due to the amount of specific GHGs in the atmosphere. Today humans use fuels like coal, natural gas, and oil. These release a GHG called carbon dioxide (CO2) into the atmosphere.
All of this CO2 is starting to affect the Earth. Continuing to increase the amount of this gas in our atmosphere will likely change the climate and could cause some species to go extinct. Because we depend on species for many different things, we do not want a changing climate to threaten their existence. This is why many people today want to decrease the amount of fossil fuels that we use.
Although the Earth’s climate is changing, there is still time to help. One way to help could be to reduce CO2 emissions. Energy sources which produce GHGs are very important to our society but making little changes to reduce the amount we each use can make things better. To reduce the energy you use, you could:
Every little bit can help and if enough people take small steps, they can add up to a huge leap.
Visit our links page to find more resources on climate change.
Darin Kopp. (2016, February 02). Crazy Climate and Wacky Weather. ASU - Ask A Biologist. Retrieved July 18, 2018 from https://askabiologist.asu.edu/explore/crazy-climate-and-wacky-weather
Darin Kopp. "Crazy Climate and Wacky Weather". ASU - Ask A Biologist. 02 February, 2016. https://askabiologist.asu.edu/explore/crazy-climate-and-wacky-weather
Darin Kopp. "Crazy Climate and Wacky Weather". ASU - Ask A Biologist. 02 Feb 2016. ASU - Ask A Biologist, Web. 18 Jul 2018. https://askabiologist.asu.edu/explore/crazy-climate-and-wacky-weather | <urn:uuid:25b3f482-4fc2-47c8-a577-eae84043c8c9> | 3.328125 | 1,430 | Knowledge Article | Science & Tech. | 59.524753 | 95,637,363 |
Humanity has long since established a foothold in the Artic and Antarctic, but extensive colonization of these regions may soon become economically viable. If we can learn to build self-sufficient habitats in these extreme environments, similar technology could be used to live on the Moon or Mars.
The average temperature of the Antarctic coast in winter is about –20 °C. As if this weren't enough, the region suffers from heavy snowfall, strong winds, and six-month nights. How can humanity possibly survive in such a hostile environment?
So far we seem to have managed well; Antarctica has almost forty permanently staffed research stations (with several more scheduled to open by 2008). These installations are far from self-sufficient, however; the USA alone spent 125 million dollars in 1995 on maintenance and operations. All vital resources must be imported—construction materials, food, and especially fuel for generating electricity and heat.
Modern technology and construction techniques may soon permit the long-term, self-sufficient colonization of such extreme environments.
Why would anyone want to live there? Exceptional scientific research aside, the Arctic is though to be rich in mineral resources (oil in particular). The Antarctic is covered by an ice sheet over a mile thick, making any mineral resources it may have difficult to access. Its biological resources, however, have great potential. Many organisms adapted to extreme cold have evolved unusual biochemical processes, which can be leveraged into valuable industrial or medical techniques. Alexander Bolonkin and Richard Cathcart are firm believers in the value of this chilling territory. "Many people worldwide, especially in the Temperate Zones, muse on the possibility of humans someday inhabiting orbiting Space Settlements and Moon Bases, or a terraformed Mars" Bolonkin points out, "but few seem to contemplate an increased use of ~25% of Earth’s surface—the Polar Regions."
Indeed, the question of space exploration is intriguing. We would all like to know whether there is life on Mars, but robot probes can only perform the experiments they take along with them. Only humans are flexible enough to explore a new territory in detail and determine whether there are enough resources to sustain a long-term presence. Does modern technology really permit the design of lightweight, energy-efficient habitats suitable for other worlds?
The Sun provides the Earth and Moon with about 1400 Watts per square meter, which is ample energy to warm a habitat even when the angle of the incident light and losses due to reflection are taken into account. On Mars, the sunshine is a little less than half as strong—which means that the equator of Mars receives about as much solar energy as the higher latitudes of Earth (Iceland, for example).
The most efficient way to generate heat from sunlight is, of course, the well-known "greenhouse" effect. Given a transparent or translucent roof, any structure can hold onto the energy of sunlight long enough to transform it into heat. Glass works well for this, but glass is heavy and expensive to transport.
Some good alternatives to glass are now available, however, and more options are on the way. Innovative manufacturing techniques have created many useful composite materials, including translucent, flexible membranes such as Saint-Gobain’s Sheerfill®. While these materials are certainly more expensive than glass, very little is required to construct a useful shelter.
In a recent article submitted to arXiv.org , Bolonkin and Cathcart have designed an inflatable, translucent dome that can heat its interior to comfortable temperatures using only the weak sunlight of high latitudes. While many details remain to be worked out, the essential concept is sound. To improve the energy efficiency of the structure, they propose adding multiple insulating layers, aluminum-coated shutters, and a fine electrical network to sense damage to the structure. The dome would be supported entirely by the pressure of the air inside, which can be adjusted to compensate for the added buoyancy caused by high winds.
The principle advantages of this design are the low weight and flexibility of the material. If only a few people at a time need shelter, an enclosure the size of a small house would weigh only about 65 kg, or as much as a person. This is light enough even for a space mission, and setting up would be as easy as turning on an air pump. For large colonies, enough membrane to enclose 200 hectares would weigh only 145 tons. The interior would be warm and sheltered, a safe environment for the construction of more traditional buildings and gardens.
Bolonkin and Cathcart have attracted attention with their proposal, but a prototype has not yet been constructed.
Source: 1996 report on the U.S. Antarctic Program by the National Science and Technology Council; www.nsf.gov/pubs/1996/nstc96rp/chiv.htm
Source: Sam Johnston, “Recent Trends in Biological Prospecting”, UN University Institute for Advanced Studies; www.ias.unu.edu/sub_page.aspx?catID=35&ddlID=20
By Ben Mathiesen, Copyright 2007 PhysOrg.com.
All rights reserved. This material may not be published, broadcast, rewritten or redistributed in whole or part without the express written permission of PhysOrg.com.
Explore further: NASA plans to send mini-helicopter to Mars | <urn:uuid:1154165b-ceaf-4b25-8afe-5790fb6a56da> | 4.1875 | 1,098 | News Article | Science & Tech. | 38.4325 | 95,637,384 |
Chapter 1: Randomness
The concept of randomness is fundamental in probability theory and statistics, but also most controversial. Among the many interpretations of terms like probability, likelihood, etc., we shall consider two in this course: the usual frequency approach (in this chapter) and the Bayesian one (in chapter 6: “Decision problems”). One should actually not speak of a single frequency approach, since there are several variations of it. That most commonly adopted in the textbook literature is to start from the idea of a random experiment and carry out the mathematical formalization as follows.
KeywordsFourier Coefficient Formal Statistical Test Congruence Generator Arbitrary Continuous Function Column Reduction
Unable to display preview. Download preview PDF. | <urn:uuid:29afd27a-b3a5-405c-811e-65e60bd12ff1> | 3.765625 | 152 | Truncated | Science & Tech. | 21.998673 | 95,637,415 |
Signals from cell phone towers could be a novel and reliable way to help predict the intensity of the next big flood, according to a new study.
A model developed by Tel Aviv University (TAU) researchers, which analyses cell phone signals, has added a critical component to weather forecasting.
“By monitoring the specific and fluctuating atmospheric moisture around cell phone towers, we can cheaply, effectively and reliably provide a more accurate 'critical moisture distribution' level for fine-tuning model predictions of big floods,” said Pinhas Alpert, geophysicist, who heads TAU Porter School for Environmental Education.
Cell phone towers emit radio waves that are diminished by moisture in the air, a factor that can be used to improve model warnings on flood levels.
Furthermore, TAU researchers measured the rainfall distributions and were able to accurately estimate the size of impending floods before they struck.
This was demonstrated in post-analysis of two case-studies of floods in the Judean Desert in Israel, where cell phone towers and flash floods are abundant.
Using real data measurements collected from the towers, the researchers demonstrated how microwave links in a cellular network correlated with surface station humidity measurements. The data provided by cell phone towers is the missing link weather forecasters need to improve the accuracy of flood forecasting.
“Our method provides reliable measurement of moisture fields near the flood zone for the first time,” noted Alpert.
This new tool, he says, can add to the bigger picture of understanding climate change patterns in general, according to a TAU release.
These findings were published in the April edition of Atmospheric Chemistry
|Get a chance to meet who's who of Transport ecosystem in India including key policymakers from Central and State Governments. Join us at National Summit on ‘Strategy for Ports, Highways Infrastructure and Logistics Efficiency , New Delhi on Aug 13, 2018 to explore business opportunities. Like and connect with us on Facebook, Linkedin and Twitter.| | <urn:uuid:fd49ae82-b0f3-4dab-9fb8-8c86c3c3776b> | 3.53125 | 403 | News Article | Science & Tech. | 21.42715 | 95,637,420 |
Marlowe Hood – February 27, 2018
Not for the first time in recent years, Europe has descended into a deep freeze while the Arctic experiences record high temperatures, leaving scientists to ponder the role global warming may play in turning winter weather upside down.
The reversal has been dramatic.
A Siberian cold front has spread sub-zero temperatures across Europe, carpeting southern cities and palm-lined Mediterranean beaches with snow.
On Sunday, meanwhile, air temperatures at the North Pole — which won’t see the Sun until March — rose above freezing.
“In relative terms, that’s a 30 C (54 degrees Fahrenheit) temperature anomaly,” Robert Rohde, lead scientist at Berkeley Earth in Washington, tweeted. | <urn:uuid:dd3ee4aa-0f63-483d-a5dd-e247bee05311> | 3.15625 | 151 | News Article | Science & Tech. | 36.049 | 95,637,424 |
Intel® Curie BSP
Intel® Curie BSP is the SDK that will help you developing software on Curie based boards, for example with the Arduino 101 board (AKA Genuino 101).
Curie BSP is the SDK dedicated to the wearable device. It is part of the Intel Software Platform for Curie which allows you to develop an End to End Application, from the Cloud, through the smartphone downto the Intel® Curie powered wearable device. For more information, visit https://iqsdk.intel.com/.
For now Curie BSP is compatible with the Arduino 101 board (see http://www.intel.com/content/www/us/en/do-it-yourself/arduino-101.html). Keep in mind that this configuration is unsupported by Arduino. After flashing a Curie BSP application, you won't be able to run an Arduino sketch anymore unless you restore the original firmware as indicated below.
The environment supports only the OS Ubuntu GNU/Linux as host.
Intel® Curie SoC documentation is available at http://www.intel.com/content/www/us/en/wearables/wearable-soc.html.
ONE TIME SETUP
Curie BSP needs a set of external projects to be built. The repo tool is currently used to fetch all the needed repositories.
wget http://commondatastorage.googleapis.com/git-repo-downloads/repo -O ~/bin/repo
chmod a+x ~/bin/repo
In ~/.bashrc add:
Create your directory (eg. Curie_BSP):
mkdir Curie_BSP && cd $_
Initialize your repo:
repo init -u https://github.com/CurieBSP/manifest
Download the sources files:
repo sync -j 5 -d
Initialize the environment:
make -C wearable_device_sw/projects/curie_hello/ one_time_setup
Backup your original Arduino 101 Software:
To be able to run back Arduino sketches and reset your Arduino 101 board to factory settings, you need to prepare a backup of the original firmware. The backup method and the hardware setup is the same as the Zephyr project one. Refer to https://www.zephyrproject.org/doc/board/arduino_101.html. The Curie BSP includes the Zephyr OS Source code in 'wearable_device_software/external/zephyr' so, no need to download it again.
BUILD AND FLASH A PROJECT
Curie BSP must be built out-of-tree, in a dedicated output directory whose location is chosen by the end user.
The recommended procedure during development phase is the following:
Prepare your build environment:
mkdir -p ./out
Setup your project, for example based on the curie_hello project:
make -f ../wearable_device_sw/projects/curie_hello/Makefile setup
make image -j 32
You first need to flash the bootloader on the board using JTAG. This have to be done only once:
make flash FLASH_CONFIG="jtag_x86_rom+bootloader"
Then you can flash your board using the standard USB port:
then press the reset button on the board to start the flashing.
To generate the documentation in the "doc" directory you can type:
Or you can generate and browse it directly using the default browser: | <urn:uuid:052eae05-f396-4abc-87be-3a7faf81b201> | 2.546875 | 754 | Tutorial | Software Dev. | 53.809065 | 95,637,427 |
Googology Wiki is an online encyclopedia and community dedicated to large numbers.
Welcome to the Internet's most comprehensive database of large numbers and fast-growing functions. We have made 10,263 articles. If you're fascinated by numbers like titanicol or golapulus, why not help us out? We encourage you to edit!
New to big numbers?
Googology is the mathematical study of large numbers, their properties, and their nomenclature. If you're interested in the subject, but you don't know where to start, try reading about some basic functions and ideas:
Also, be sure to check out the links below.
Around the Wiki
Article Count Progress
We have reached 0% of our goal of 10100 articles!
Counting this way for unspeakable eons,
—from the Avatamsaka Sutra
Found googology from a third-party source that isn't in the encyclopedia yet? Create a new article. Article creation is temporarily banned whilst notability guidelines are being revised.
This is a compilation of websites that may be of interest to large number enthusiasts. | <urn:uuid:62d6eda7-a6e1-4358-b523-52ec42925b9d> | 2.640625 | 232 | Content Listing | Science & Tech. | 42.404606 | 95,637,453 |
Nasa's new mission will measure Earth's rain and snowfall to better predict the devastating power of storms
- Global Precipitation Measurement mission has launched its first satellite
- It will provide real-time measurements of rain and snow every three hours
- This will extend the detailed radar map of local areas to all over the world
- Currently there are huge gaps in precipitation observations, particularly around the north and south poles
Recent extreme weather events have highlighted just how important it is to understand our planet’s behaviour.
And now a new space mission could help do just that by providing real-time measurements of rain and snow every three hours, all over the world.
The constellation of satellites will help fill huge gaps in precipitation observations as large areas of the Earth currently do not have radar coverage.
The satellite has unprecedented range, and will scan the skies between 65 degrees north and south latitude
The mission, known as Global Precipitation Measurement (GPM), will also help scientists look through storms to see the internal dynamics and intensity of a hurricane.
The satellite has unprecedented range, and will scan the skies between 65 degrees north and south latitude.
Currently, Nasa’s Tropical Rainfall Measurement Mission (TRMM) provides scientists with detailed data on rainfall and storms.
But the problem is it only covers a relatively narrow range. For instance, Hurricane Sandy could only be tracked by TRMM until it passed Florida before going out of range.
The first satellite of the constellation, known as the Global Precipitation Measurement (GPM) Core Observatory, was launched on Thursday by Nasa and the Japan Aerospace Exploration Agency (Jaxa)
GPM SCIENCE APPLICATIONS
- Improved knowledge of the Earth’s water cycle and its link to climate change
- New insights into storm structures and larger-scale atmospheric processes
- Better ability to monitor and predict hurricanes
- Improved ability to forecast natural disasters, including floods, droughts and landslides
- Better agricultural crop forecasting and monitoring of freshwater resources
While TRMM measures precipitation in the tropics, the new constellation will also expand the coverage area from the Arctic Circle to the Antarctic Circle.
This is vital to understanding extreme events, like blizzards, floods and droughts which have wreaked havoc across the globe in recent months.
The first satellite of the constellation, known as the Global Precipitation Measurement (GPM) Core Observatory, was launched on Thursday by Nasa and the Japan Aerospace Exploration Agency (Jaxa).
‘With this launch, we have taken another giant leap in providing the world with an unprecedented picture of our planet's rain and snow,’ said Nasa administrator Charles Bolden.
‘GPM will help us better understand our ever-changing climate, improve forecasts of extreme weather events like floods, and assist decision makers around the world to better manage water resources.’
GPM is one of the ¿core¿ satellites in the constellation and will be carrying an advanced radar and radiometer system to measure precipitation from space. Pictured is the launch which took place on Thursday
GPM will also be able to detect light rain and snowfall, a major source of available fresh water in some regions.
‘We still have a lot to learn about how rain and snow systems behave in the bigger Earth system,’ said GPM project scientist Gail Skofronick-Jackson of Goddard.
‘With the advanced instruments on the GPM Core Observatory, we will have for the first time frequent unified global observations of all types of precipitation, everything from the rain in your backyard to storms forming over the oceans to the falling snow contributing to water resources.’
GPM is one of nine satellites in the constellation and will be carrying an advanced radar and radiometer system to measure precipitation.
The GPM Core Observatory is the first of Nasa’s five Earth science missions launching this year.
Most watched News videos
- Members of Congress give warnings after 'disgraceful' summit
- Moment off-duty cop shoots armed motorbike thief dead
- Donald Trump goes golfing at his Trump Turnberry club in Scotland
- 'Trump told me I should sue the EU': Prime Minister Theresa May
- Love Island TEASER: Georgia gets anxious as she could be kicked off
- France fans scuffle with police in Paris following World Cup win
- Violent footage shows fight using baskets at Poundland store
- Obama dances with his step grandmother during visit to Kenya
- Fans celebrate in Paris as France beat Croatia 4-2 to win World Cup
- David Davis won't make a resignation speech in the Commons
- Shocking video shows driver knocking cyclists off their bikes
- Lacoste store in Lyon looted following France's world cup win | <urn:uuid:ec10ab86-8f0e-4d15-860e-882f2f531743> | 3.171875 | 984 | News Article | Science & Tech. | 16.928737 | 95,637,460 |
Introduction to Redox Reactions
Oxidation-reduction reactions (often abbreviated as redox) involve the
transfer of electrons. Many important chemical reactions involve oxidation and
reduction. Photosynthesis, which stores energy from the sun in plants by
converting carbon dioxide and water into sugar, is a very important
oxidation-reduction reaction. Combustion reactions, which provide most of the
energy to power our civilization, also involve oxidation and reduction. An
example of this is the combustion of methane with oxygen:
CH4(g) + 2O2(g) → CO2(g) + 2H2O(g) + energy
Even though none of the reactants or products is ionic, the reaction is nonetheless assumed
to involve the transfer of electrons from carbon to oxygen.
Suppose you are to balance the following reaction occurring in an acidic solution:
MnO4-(aq) + Fe2+ →Fe3+(aq) + Mn2+(aq)
How would you balance such an equation? You might think to yourself that this is impossible, since the oxygen atoms “disappear” and that violates the Law of Conservation of Mass. But this reaction indeed occurs. Thus we need to develop a new approach to balance oxidation-reduction reactions.
What is Oxidation and Reduction?
For oxidation-reduction reactions that occur in aqueous solution, we break the reaction up into two parts, or two half-reactions:one involving oxidation and the other involving reduction. Oxidation involves an increase in oxidation state. Consider the following half reaction:
Sn2+(aq) → Sn4+(aq)
The Sn2+ ion increases in oxidation state becoming “more positive”: it is oxidized. This means that oxidation involves losing electrons. The complete opposite is true for the process of reduction. Reduction involves a decrease in oxidation state. Consider the following half reaction:
Al3+(aq) → Al(s)
The Al3+ ion decreases in oxidation state-it becomes “more negative”:
it is reduced. Thus, reduction involves gaining electrons.
A useful reminder is OIL RIG: Oxidation Is Loss,Reduction Is Gain
Now that you have a basic understanding of the concept of oxidation and reduction, now you must learn how to balance redox equations. It is not hard, but practice is critical. The reactions we’re concerned with will occur in either acidic or basic solutions. Therefore, there will be two ways to balance redox reactions depending whether or not it occurs in acidic or basic solution. (You will be told whether the solution is basic or acidic).
The Half-Reaction Method for
Balancing Redox Reactions in Acidic Solutions
Returning to the equation earlier: MnO4-(aq) + Fe2+ →Fe3+(aq)+ Mn2+(aq)
Let’s develop a simple method for balancing this equation in acidic solution. The following method applies to any redox reaction occurring in acidic solutions. I will break it down into steps to reduce confusion.
MnO4-(aq) + Fe2+ →Fe3+(aq) + Mn2+(aq)
1) Identify which substance is reduced and which one is oxidized
Mn7+(aq) + 4O2-(aq) + Fe2+(aq)
→ Fe3+(aq) + Mn2+(aq)
You can see that Mn goes from +7 charge to +2 charge, which means that Mn is reduced. You also notice that Fe goes from +2 to +3, thus Fe is oxidized.
2) Write out the oxidation and reduction half reactions
MnO4- → Mn2+ Fe2+ →Fe3+
The permanganate ion appears to be oxidized, but it is really reduced.
3) Balance all elements except hydrogen and oxygen
All other elements are already balanced in this case
4) Balance oxygen atoms using water
MnO4- → Mn2+ + 4H2O Fe2+ →Fe3+ (no oxygen to balance)
5) Balance hydrogen using H+ ions
8H+ + MnO4- → Mn2+ + 4H2O Fe2+ →Fe3+ (no hydrogen to balance)
6) Balance the charges using e (electrons)
5e+ 8H+ + MnO4- → Mn2+ + 4H2O Fe2+ →Fe3+ + e
7) Be sure both equations have the same number of electrons. If they don’t, then multiply one of them by some factor so they have the same number of electrons.
5e+ 8H++ MnO4- → Mn2+ + 4H2O Fe2+ →Fe3+ + e
5 electrons 1 electron
The two equations do not have the same number of electrons! But if we multiply the oxidation reaction by a factor of 5, then the equation will have 5 electrons:
5 X (Fe2+ →Fe3+ e) = 5Fe2+ →5Fe3+ +5e
8) Add the two reactions together. Cancel out common species.
5e+ 8H+ + MnO4- → Mn2++ 4H2O
+ 5Fe2+ →5Fe3+ +
5e (electrons should ALWAYS cancel out)
Balanced Equation: 8H+ + MnO4- + 5Fe2+ → Mn2+ + 4H2O + 5Fe3+
This may seem like a lot of work. But if you practice, you’ll be able to skip some of
the steps and balance these reactions fairly quickly. | <urn:uuid:04bf9804-94e2-4b57-bb52-1183cda38e26> | 4 | 1,200 | Tutorial | Science & Tech. | 46.858895 | 95,637,464 |
In the city that never sleeps, it's easy to overlook the insects underfoot. But that doesn't mean they're not working hard. A new study from North Carolina State University shows that insects and other arthropods play a significant role in disposing of garbage on the streets of Manhattan.
"We calculate that the arthropods on medians down the Broadway/West St. corridor alone could consume more than 2,100 pounds of discarded junk food, the equivalent of 60,000 hot dogs, every year - assuming they take a break in the winter," says Dr. Elsa Youngsteadt, a research associate at NC State and lead author of a paper on the work.
"This isn't just a silly fact," Youngsteadt explains. "This highlights a very real service that these arthropods provide. They effectively dispose of our trash for us."
The researchers were in the midst of a long-term study of urban insects when Hurricane Sandy struck NYC in 2012. In spring 2013, they expanded their study to look at whether Sandy had affected the behavior of these insect populations.
The research team sampled arthropods - such as insects and millipedes - in street medians and parks in Manhattan to measure the biodiversity at those sites. The researchers also wanted to see how much garbage those arthropods consumed and whether they consumed more in some places than in others. One hypothesis was that in areas with more biodiversity, insects would consume more garbage.
To see how much the arthropods ate, the researchers put out carefully measured amounts of junk food - potato chips, cookies and hot dogs - at sites in street medians and city parks. Researchers placed two sets of food at each site. One set was placed in a cage, so only arthropods could reach the food; the second set was placed in the open, where other animals could also eat it. After 24 hours, the scientists collected the food to see how much was eaten.
The researchers found that Hurricane Sandy had no measurable impact on food consumption by arthropod populations in New York, which was somewhat surprising since many of the study sites had been flooded with brackish water.
The bigger surprise was that arthropod populations in medians ate two to three times more junk food than those in parks - even though there was less biodiversity in the medians.
"We think this is because one of the most common species in the medians was the pavement ant (Tetramorium species), which is a particularly efficient forager in urban environments," Youngsteadt says.
In addition, by comparing food consumption inside and outside of the sample cages, the researchers showed that other animals - such as rats and pigeons - were also eating the junk food.
"This means that ants and rats are competing to eat human garbage, and whatever the ants eat isn't available for the rats," Youngsteadt explains. "The ants aren't just helping to clean up our cities, but to limit populations of rats and other pests."
The paper, "Habitat and species identity, not diversity, predict the extent of refuse consumption by urban arthropods," was published online Dec. 2 in the journal Global Change Biology. The paper was co-authored by former NC State undergraduate Ryanna Henderson; Dr. Amy Savage, a postdoctoral researcher at NC State; Andrew Ernst, a research assistant at NC State; Dr. Rob Dunn, an associate professor of biological sciences at NC State; and Dr. Steven Frank, an associate professor of entomology at NC State.
The work was supported by NSF RAPID grant number 1318655 and by the Department of the Interior's Southeast Climate Science Center, under cooperative agreement numbers G11AC20471 and G13AC00405. The center is based at NC State and provides scientific information to help land managers respond effectively to climate change.
Matt Shipman | EurekAlert!
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
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 | Life Sciences
17.07.2018 | Information Technology
17.07.2018 | Power and Electrical Engineering | <urn:uuid:6332ba6b-18e3-4848-a225-937c2942b638> | 3.03125 | 1,447 | Content Listing | Science & Tech. | 45.083019 | 95,637,467 |
PHP String Handling Multiple Choice Questions 1 PDF Download
Practice php string handling multiple choice questions (MCQs), php test 1 for online course prep exams. Learn strings in php MCQs questions and answers on strings in php, string replacement, comparison and searching with answers.
Free php string handling quiz online, study guide has multiple choice question on a sequence of characters that is treated as a unit is called with options functions, arrays, methods and strings to test online e-learning skills for viva exam prep and job's interview questions with answers key. Study to learn strings in php quiz questions with online learning MCQs for competitive exam preparation test.
MCQ on PHP String Handling Quiz PDF Download Test 1
MCQ. A sequence of characters that is treated as a unit is called
MCQ. The ltrim ( ) returns its string argument with
- Leading blankspace removed
- Trailing blankspace removed
- Numerical values
- None of them
MCQ. When two strings are exactly equivalent Strcmp ( ) returns what?
- Returns a string
- Returns 0
- Returns 1
- Returns nothing
MCQ. For finding out one string is equal to another string which function we can use?
- strpid ( )
- strpos ( )
- str ( )
- All of them
MCQ. Returns a string arguments with trilling blank space removed, is a behavior of
- starts ( ) function
- chop ( ) function
- rtrim ( ) function
- Both B and C | <urn:uuid:e56146da-95e5-4904-9141-8b5ecda8f909> | 3.140625 | 325 | Tutorial | Software Dev. | 64.088353 | 95,637,477 |
Creep in 4 faults means big quake may be poised to hit
Four highly stressed seismic faults in the Bay Area’s densely populated San Andreas system are moving on the surface and could rupture in a major earthquake at any time, according to scientists tracking their movements.
The faults include the Calaveras, which runs roughly from Hollister (San Benito County) to Danville; the Hayward, between Suisun Bay and San Jose; the Rodgers Creek Fault in southern Sonoma County; and the Green Valley Fault, which runs roughly from Vallejo to Fairfield.
“The extent of fault creep controls the size and timing of large earthquakes, and measuring that creep rate helps tell us how much strain is building up on the faults underground — although it can’t tell us when a fault will rupture in a quake,” said geophysicist James J. Lienkaemper of the U.S. Geological Survey in Menlo Park, who led the study.
Lienkaemper and his colleagues have been analyzing the rates of those tiny continuous movements along Northern California faults for years. The movement is only a few millimeters a year, but the effects over the years can be visible in roadside cracks and offset curbs.
LATEST SFGATE VIDEOS
- Saint Marys PMBA San Francisco Chronicle
- Hult San Francisco Campus San Francisco Chronicle
- Humpbacks lunging near boat in Monterey Bay Princess Monterey Whale Watch
- Watch SF's world-famous summer fog roll in San Francisco Chronicle
- Terrifying video shows a swirling column of fire in SoCal San Francisco Chronicle
- Lost bulldog reunited with owner in Antioch San Francisco Chronicle
- Dolores Hill Bomb 2018: Skateboarders descend on San Francisco's Mission District Derek John Dudek / derekdudekdesign.com
- Dolores Hill Bomb 2018: Skateboarders descend on San Francisco's Mission District Desi Pena
- A Conversation with London Breed Manjula Varghese
- SF's Boxing Room makes New Orleans cocktails SFGATE
The surface movements of a fault can relieve a certain amount of stress, but deep underground, the faults can remain locked for centuries until they finally rupture in a full-scale, damaging earthquake, Lienkaemper said.
The scientists’ report was published Monday in the Bulletin of the Seismological Society of America.
They estimate that the next major quake on any of the four faults could be comparable to the 6.9-magnitude Loma Prieta quake 25 years ago, which killed 63 people and caused $6 billion in damage. Lienkaemper and his colleagues said the Hayward Fault, long considered the most likely to rupture in the near future, could eventually trigger a magnitude 6.8 quake. The Calaveras Fault could also rupture with a magnitude of 6.8; the Rodgers Creek and the Green Valley faults could each yield a magnitude of 7.1.
The Hayward Fault last ruptured in 1868, with the magnitude now estimated at 6.8, while the Rodgers Creek Fault last broke in 1745, according to evidence uncovered by trenches scientists have dug in the area. The last known major earthquake on the Calaveras Fault struck about 1740, and on the Green Valley Fault, the last rupture occurred about 1609.
“Given how long ago they had their last earthquakes, they are more than ready to produce a major earthquake again now,” said Roland Burgmann, a geophysicist and expert on crustal deformation at UC Berkeley who was not involved in Lienkaemper’s report.
For 35 years, San Francisco State University has maintained a Fault Creep Monitoring Program that enlists students, technicians and faculty to measure the barely perceptible signs of fault creep using surveyors’ tools called theodolites and — more recently — GPS instruments.
Lienkaemper now leads that project, and his team’s report is based on the project’s measurements of creep rates over the years on many faults, from quake-prone Parkfield on the San Andreas fault in southern Monterey County to Humboldt County, where the fault veers out to sea and joins undersea faults in what scientists call the Mendocino Triple Junction. | <urn:uuid:6d4863c8-40e3-4af5-8b76-d582ca908fd3> | 2.640625 | 887 | News Article | Science & Tech. | 41.422019 | 95,637,484 |
Join the Conversation
To find out more about Facebook commenting please read the Conversation Guidelines and FAQs
Why scientists say it's too soon to place blame for the Eastpoint fire
Eastpoint fire drone footage, aerial photos display degree of devastation Drone footage courtesy of Aervisum.com, Tallahassee Democrat
Even as elected officials blame the Limerock Wildfire that gutted dozens of homes in Eastpoint on an errant prescribed fire, forestry scientists are urging caution about assigning fault.
"Until all the facts come in ... It’s very important not to assign blame," said Kevin Hiers, a wildland fire scientist at Tall Timbers, a Tallahassee-based fire ecology research group. “It’s a very tragic situation. My heart goes out to the individuals no matter what the cause of it is."
Given the vagaries of nature, many things could go wrong after a prescribed burn.
Reed Noss, an ecology expert who specializes in conservation biology, said "stored" smolders could linger for days or weeks in old tree stumps or logs after a burn. Under the right conditions, drought or extreme wind, for example, those smolders could reignite.
A prescribed burn was performed live before an audience at the inaugural Red Hills Fire Fest at Tall Timbers. Ryan Dailey/Democrat
While Noss was uncomfortable speaking about the specifics of the Eastpoint case, he explained that unforeseen circumstances can cause a reignition.
“You could have a fire that would be on its way to going out that could be suddenly reignited,” he said. “It’s one of these things that is not predictable — it’s a chance event of nature that is not the fault of a manager, and it’s just one of those things that can happen.”
The origins of the Eastpoint fire and the political implications of the disaster are not lost on scientists after Agriculture Commissioner Adam Putnam declared that a state contractor caused the wildfire in a prescribed burn gone wrong.
North Florida and southern Georgia have been the fire ecological science lab where many of the modern forestry conservation methods have been developed, tried and proven.
Prescribed burns, sometimes called controlled burns, are conservation methods meant to help prevent destructive wildfires and support growth of healthy vegetation by releasing trapped nutrients.
The practice is a source of pride for the Florida Forest Service. In 2017, there were 2 million acres of authorized prescribed burns, according to FFS data provided to the Southern Fire Exchange, with 81,174 prescribed fires authorized. Of those, less than a tenth of a percent escaped into a wildfire.
In the last decade, 2.7 percent of all Florida wildfires were escaped prescribed burns, according to FFS numbers.
Carrying out a controlled burn is a very careful science, Noss said. Before one is administered by certified, prescribed burning professionals, a written plan has to be approved at many levels.
If something does go wrong, a thorough “after action review” is conducted, explained Hiers.
Wildlands Service Inc., the contractor, was hired to conduct a burn on June 18 on nearly 500 acres in the Apalachicola River Wildlife and Environmental Area, which is separated from the devastated Eastpoint neighborhood by 600 acres of private land. The Limerock Wildfire that began six days later scorched more than 800 acres.
FWC is investigating to ensure all protocol and operations for prescribed burns were followed.
In the meantime, the agency has halted its burn program. Noss called that a "knee-jerk" reaction. Shutting the program down could derail scientists' efforts to educate the public about the program's benefits.
"That’s a very clear danger every time you have a major fire mistake," Noss said. "If you don’t have regular controlled burning, you’re going to have more destructive wildfires and you’re going to lose a lot of our native biodiversity."
Hiers explained that in Florida, prescribed fire actually helps prevent destructive wildfires by reducing potential fuel.
"Wildfires are an inevitability in Florida and prescribed fire is and will remain our number one tool to mitigate that risk," Hiers said.
By tradition, most fire managers in Florida conduct controlled burns in the winter. But there's no consensus on when is the best time or what is the best season.
"Some claim it’s easier to control in the winter," Noss said, "but others dispute that."
The season's cooler temperatures also make it a more comfortable task for managers in heavy suits to conduct the burn. But now, lots of studies show, from an ecological standpoint, it’s better to burn during months when the most lightning-induced fires occur, he said. In Florida, that's between late April and early July.
"That kind of evolutionary fire season goes back at least tens of thousands, probably hundreds of thousands to millions of years," Noss said.
A Clemson University article assessing seasonal benefits and risks of prescribed burns in longleaf pine management says winter burns after a cold front are "easy to plan and control," while summer's sudden thunderstorms and variable winds can complicate burn plans.
"Therefore," the article states, "the weather must be carefully monitored and burns in this season should be directed by unusually experienced personnel." | <urn:uuid:70f8f62c-6655-41e8-a4ed-bb5fb8e2a268> | 3.1875 | 1,109 | News Article | Science & Tech. | 41.384156 | 95,637,485 |
Is it possible to Format the Text of a TextBox to display 3 digits even if the user has entered only a single digit?
e.g. the user entered "5", but I want to display it as "005".
I don't want to use MaskedTextBox.
In VB 6, it was as simple as
TextBox1.Text = Format(Val(TextBox1.Text),"000")
How can I get the same result in C# 2005??
Lalit Kumar Barik | <urn:uuid:ce3b194d-a51a-457c-a485-d87d86f8ec08> | 2.71875 | 109 | Q&A Forum | Software Dev. | 90.82414 | 95,637,499 |
While scientists and policy experts debate the impacts of global warming, the Earth’s soil is releasing roughly nine times more carbon dioxide to the atmosphere than all human activities combined. This huge carbon flux from soil—due to the natural respiration of soil microbes and plant roots—begs one of the central questions in climate change science: As the global climate warms, will soil respiration rates increase, adding even more carbon dioxide to the atmosphere and accelerating climate change?
Previous experimental studies of this question have not produced a consensus, prompting Marine Biological Laboratory scientists Joanna Carey, Jianwu Tang and colleagues to synthesize the data from 27 studies across nine biomes, from the desert to the Arctic. Their analysis, published this week in Proceedings of the National Academy of Sciences, represents the largest dataset to date of soil respiration response to experimental warming.
One prediction from this synthesis is that rising global temperatures result in regionally variable responses in soil respiration, with colder climates being considerably more responsive. “Consistently across all biomes, we found that soil respiration increased with soil temperature up to about 25 degrees Celsius (77 degrees Fahrenheit),” said Carey, a postdoctoral scientist in the MBL Ecosystems Center. Above the 25-degree Celsius threshold, respiration rates decreased with further increases in soil temperature.
“That means the Arctic latitudes, where soil temperatures rarely, if ever, reach 25 degrees Celsius, will continue to be most responsive to climate warming. Because there is so much carbon stored in frozen soils of the Arctic, this has really serious repercussions for future climate change,” Carey said.
The team also found that soil microbes in experimental warming studies showed no sign of adaptation—meaning a muted respiration response to rising temperatures—in all of the biomes studied, except desert and boreal forest. This indicates that “soils will typically respond strongly to increasing temperature by releasing more carbon dioxide,” said Tang, the study’s lead investigator.
To understand how global carbon in soils will respond to climate change, the authors stress, more data are needed from under- and non-represented regions, especially the Arctic and the tropics.
Other MBL scientists who contributed to this study include Mary Heskel, Jerry Melillo, Edward B. Rastetter and Gaius R. Shaver. | <urn:uuid:4c335257-243d-4772-92a7-ae123782b33c> | 3.765625 | 480 | News Article | Science & Tech. | 19.653242 | 95,637,516 |
Science, Natural Phenomena & Medicine
Friday, January 18, 2013
is a synthetic radioactive element, which has ten isotopes, produced by bombardment of plutonium or uranium. Symbol Fm; atomic n
mber 100; valence 2 and 3. It was named after Enrico Fermi, the Italian physicist. | <urn:uuid:e0fa8a94-5616-469b-b74c-9b1f44620445> | 2.984375 | 67 | Knowledge Article | Science & Tech. | 34.891318 | 95,637,518 |
Tad Pfeffer, a fellow of CU-Boulder's Institute of Arctic and Alpine Research and his colleagues made calculations using conservative, medium and extreme glaciological assumptions for sea rise expected from Greenland, Antarctica and the world's smaller glaciers and ice caps -- the three primary contributors to sea rise. The team concluded the most plausible scenario, when factoring in thermal expansion due to warming waters, will lead to a total sea level rise of roughly 3 to 6 feet by 2100.
While the disintegrating Columbia Glacier is adding to ocean levels this century, the total global sea rise by 2100 may be lower than many are anticipating, according to a new University of Colorado at Boulder study. Credit: Tad Pfeffer, University of Colorado
A paper on the subject was published in the Sept. 5 issue of Science. Co-authors of the study were of the University of Montana's Joel Harper and Shad O'Neel of the Scripps Institute of Oceanography at the University of California, San Diego. The study was funded by the National Science Foundation and a University of Colorado Faculty Fellowship.
"We consider glaciological conditions required for large sea level rise to occur by 2100 and conclude increases of 2 meters are physically untenable," the team wrote in Science. "We find that a total sea level rise of about 2 meters by 2100 could occur under physically possible glaciological conditions but only if all variables are quickly accelerated to extremely high limits."
"The gist of the study is that very simple, physical considerations show that some of the very large predictions of sea level rise are unlikely, because there is simply no way to move the ice or the water into the ocean that fast," said Pfeffer.
The team began the study by postulating future sea level rise at about 2 meters by 2100 produced only by Greenland, said Pfeffer. Since rapid, unstable ice discharge into the ocean is restricted to Greenland glacier beds based below sea level, they identified and mapped all of the so-called outlet glacier "gates" on Greenland's perimeter -- bedrock bottlenecks most tightly constraining ice and water discharge.
"For Greenland alone to raise sea level by two meters by 2100, all of the outlet glaciers involved would need to move more than three times faster than the fastest outlet glaciers ever observed, or more than 70 times faster than they presently move," said Pfeffer. "And they would have to start moving that fast today, not 10 years from now. It is a simple argument with no fancy physics."
In Antarctica, the majority of ice entering the ocean comes from the Antarctic Peninsula and the Pine Island and Thwaites glaciers, said Pfeffer. Most of the marine-based ice in West Antarctica is held behind the Ross and Filcher-Ronne ice shelves, which Pfeffer's team believes are unlikely to be removed by climate or oceanographic processes during the next century. The researchers used varying glacier velocities to calculate sea-rise contribution estimates from the Antarctic Peninsula, Pine Island and Thwaites glaciers.
The team also used assessments of the world's small glacier and ice cap contributions to sea level rise calculated by a CU-Boulder team and published in Science in July 2007. That study indicated small glaciers and ice caps contribute about 60 percent of the world's ice to oceans at present, a percentage that is accelerating.
Considering all major sources of sea level rise, including Greenland, Antarctica, smaller glaciers and ice caps and the thermal expansion of water, the team's most likely estimate of roughly 3 to 6 feet by 2100 is still potentially devastating to huge areas of the world in low-lying coastal areas, said Pfeffer.
Some scientists have theorized that continuing warming trends in Greenland and Antarctica could warm the Earth by 4 degrees F over the present by 2100. The last time that happened, roughly 125,000 years ago during the last interglacial period, glacier changes raised sea level by 12 to 20 feet or more. But the time scale is poorly constrained and may have required millennia, Pfeffer said.
"In my opinion, some of the research out there calling for 20 or 30 feet of sea rise by the end of the century is not backed up by solid glaciological evidence," said Pfeffer.
Policymakers need to be able to predict sea level accurately if communities, cities and countries around the world are going to be able to plan effectively, Pfeffer said. "If we plan for 6 feet and only get 2 feet, for example, or visa versa, we could spend billions of dollars of resources solving the wrong problems."
Tad Pfeffer | 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
18.07.2018 | Materials Sciences
18.07.2018 | Life Sciences
18.07.2018 | Health and Medicine | <urn:uuid:8e85536d-dd8d-48a1-a41c-89059b24ba37> | 3.546875 | 1,571 | Content Listing | Science & Tech. | 40.684551 | 95,637,520 |
Please consider donating to Behind the Black, by giving either a one-time contribution or a regular subscription, as outlined in the tip jar to the right or below. Your support will allow me to continue covering science and culture as I have for the past twenty years, independent and free from any outside influence.
Because Rosetta’s star tracker became confused by dust particles, the spacecraft lost contact with Earth, went into safe mode, and required the entire weekend for engineers to regain control.
“We lost contact with the spacecraft on Saturday evening for nearly 24 hours,” says Patrick Martin, ESA’s Rosetta mission manager. “Preliminary analysis by our flight dynamics team suggests that the star trackers locked on to a false star – that is, they were confused by comet dust close to the comet, as has been experienced before in the mission.” This led to spacecraft pointing errors, which triggered the safe mode. Unfortunately the star trackers then got hung in a particular sub mode requiring specific action from Earth to recover the spacecraft.
“It was an extremely dramatic weekend,” says Sylvain Lodiot, ESA’s Rosetta spacecraft operations manager.”
The spacecraft has been diving to within only a few miles of the surface of Comet 67P/C-G, which means it is flying close to the comet’s coma. The increased dust in that region has confused the star tracker in the past, but this appears to have been the most serious event yet. | <urn:uuid:f1665bc2-a096-4f87-b51d-a0ea76c82775> | 2.671875 | 311 | News Article | Science & Tech. | 40.522098 | 95,637,522 |
Although the genes essential for life have been identified in less complex model organisms, their elucidation in human cells has been hindered by technical barriers. We used extensive mutagenesis in haploid human cells to identify approximately 2000 genes required for optimal fitness under culture conditions. To study the principles of genetic interactions in human cells, we created a synthetic lethality network focused on the secretory pathway based exclusively on mutations. This revealed a genetic cross-talk governing Golgi homeostasis, an additional subunit of the human oligosaccharyltransferase complex, and a phosphatidylinositol 4-kinase β adaptor hijacked by viruses. The synthetic lethality map parallels observations made in yeast and projects a route forward to reveal genetic networks in diverse aspects of human cell biology.
Mendeley saves you time finding and organizing research
Choose a citation style from the tabs below | <urn:uuid:a8ff62a7-5295-4d77-9163-b6b7e864bfbe> | 2.546875 | 178 | Academic Writing | Science & Tech. | -2.026826 | 95,637,571 |
Trabajo integrador 2009
Tema: Planeta Marte.
Año lectivo: 2.009
Curso: Ciclo Turno Noche.
Alumnos: Porzio, Gonzalo.
1. Texto a traducir.
Mars is the fourth planet from the Sun in the Solar System. The planet is named after Mars, the Roman god of war. It is also referred to as the"Red Planet" because of its reddish appearance, due to iron oxide prevalent on its surface.
Mars is a terrestrial planet with a thin atmosphere, having surface features reminiscent both of the impact craters of the Moon and the volcanoes, valleys, deserts and polar ice caps of Earth. It is the site of Olympus Mons, the highest known mountain in the Solar System, and of Valles Marineris, thelargest canyon. Furthermore, in June 2008 three articles published in Nature presented evidence of an enormous impact crater in Mars's northern hemisphere, 10,600 km long by 8,500 km wide, or roughly four times larger than the largest impact crater yet discovered, the South Pole-Aitken basin. In addition to its geographical features, Mars’ rotational period and seasonal cycles are likewise similar tothose of Earth.
Until the first flyby of Mars by Mariner 4 in 1965, many speculated that there might be liquid water on the planet's surface. This was based on observations of periodic variations in light and dark patches, particularly in the polar latitudes, which looked like seas and continents, while long, dark striations were interpreted by some observers as irrigation channels for liquidwater. These straight line features were later proven not to exist and were instead explained as optical illusions. Still, of all the planets in the Solar System other than Earth, Mars is the most likely to harbor liquid water, and perhaps life. Radar data from Mars Express and the Mars Reconnaissance Orbiter have revealed the presence of large quantities of water ice both at the poles (July 2005)and at mid-latitudes (November 2008). The Phoenix Mars Lander directly sampled water ice in shallow martian soil on July 31, 2008.
Mars has approximately half the radius of Earth. It is less dense than Earth, having about 15% of Earth's volume and 11% of the mass. Its surface area is only slightly less than the total area ofEarth's dry land. While Mars is larger and more massive than Mercury, Mercury has a higher density. This results in a slightly stronger gravitational force at Mercury's surface. Mars is also roughly intermediate in size, mass, and surface gravity between Earth and Earth's Moon (the Moon is about half the diameter of Mars, whereas Earth is twice; the Earth is about ten times more massive than Mars, andthe Moon ten times less massive). The red-orange appearance of the Martian surface is caused by iron(III) oxide, more commonly known as hematite, or rust.
Based on orbital observations and the examination of the Martian meteorite collection, the surface of Mars appears to be composed primarily of basalt. Some evidence suggests that a portionof the Martian surface is more silica-rich than typical basalt, and may be similar to andesitic rocks on Earth; however, these observations may also be explained by silica glass. Much of the surface is deeply covered by finely grained iron (III) oxide dust.
Although Mars has no evidence of structured global magnetic field, observations show that parts of the planet's crust have been magnetized andthat alternating polarity reversals of its dipole field have occurred. This paleomagnetism of magnetically susceptible minerals has properties that are very similar to the alternating bands found on the ocean floors of Earth. One theory, published in 1999 and re-examined in October 2005, is that these bands demonstrate plate tectonics on Mars 4 billion years ago, before the planetary dynamo...
Leer documento completo
Regístrate para leer el documento completo. | <urn:uuid:98fb1fee-11f3-46bd-b45e-ee58b4f06294> | 3.546875 | 821 | Truncated | Science & Tech. | 40.528237 | 95,637,622 |
+44 1803 865913
By: Ian Livingstone and Ian Warren
224 pages, B/w illus
Covers the full range of the effects of the wind on Earth's surface landforms, not only in hot deserts but also on coastlines, in cold polar environments, and wherever aeolian processes are significant. The most familiar features and processes - dust storms, soil erosion by wind, sand dunes and loess - are covered in full detail. The authors also discuss the activity of wind in the past, as well as contemporary environmental hazards caused by the wind's interaction with the solid Earth.
There are currently no reviews for this book. Be the first to review this book!
Your orders support book donation projects
I just received my book from you - it arrived quickly and in perfect condition because it was packed so well.
Search and browse over 110,000 wildlife and science products
Multi-currency. Secure worldwide shipping
Wildlife, science and conservation since 1985 | <urn:uuid:ad087c29-0d92-46a5-b605-add35407d348> | 2.765625 | 204 | Product Page | Science & Tech. | 48.457911 | 95,637,624 |
An invisible workhorse of the Atlantic Ocean tirelessly shuffles cold and warm water back and forth between tropical and Arctic waters, dragging heat away from the equator. Scientists credit rich Atlantic fisheries and mild Mediterranean winters with the sheer power of the Atlantic meridional overturning circulation, or AMOC. But, last week scientists confirmed the circulation system is being jeopardized by climate-changing pollution. Changes appear to be occurring more quickly than had been anticipated, and they could accelerate in the decades ahead. The flow is presumably being throttled by an influx of freshwater pouring off a melting ice sheet — back to levels in recent decades that likely haven’t been seen in more than a millenium.
With Arctic melt hastening, and ocean circulations weakening, findings from a flurry of recent AMOC research is warning of potentially chilling consequences.
New analyses of data are linking a recent year-long AMOC slowdown with cold winters across Europe, with the frenetic 2010 Atlantic hurricane season, and with a spike in sea levels on the East Coast of the U.S. The pioneering analyses are offering clues as to how a more permanent slowdown could reshape the region. They’re being hobbled, however, by the fact that only one such abrupt slowdown has been recorded so far, and that a more permanent slowdown could behave differently.
“We’ve measured for 10 years, and we had a substantial event in one and a half years out of that 10,” University of Southampton professor Harry Bryden, who has been involved with some of the analysis, said. “I’d like to have several more events.”
Attempts to model the entire effects of an AMOC slowdown, or even a complete shutdown, have been limited by computer power. A modeling study published this month in Climate Dynamics by U.K.-based researchers links stormier conditions, sharp changes in rainfall patterns and cooling in Europe with a hypothetical AMOC slowdown. But the models used didn’t account for greenhouse gas pollution or global warming — which would blunt or worsen some of those impacts, such as by lessening winter chills.
This index shows the weakening of the Atlantic meridional overturning circulation. Credit: Nature Climate Change
“We can’t turn around and say, ‘Oh, this is what’s going to happen,’ ” Met office scientistLaura Jackson, who led the research, said.
More speculatively, in a post this week on RealClimate, Stefan Rahmstorf, head of earth system analysis at the Potsdam Institute for Climate Impact Research in Germany, suggested that the ongoing AMOC slowdown could be linked with the unusually cold weather that residents of the U.S. East Coast endured over winter. “I am just connecting the dots of some articles in the published literature, hoping this post might stimulate further investigation,” he wrote.
All of which helps make the decade’s worth of data from the RAPID array of ocean monitoring devices, which Bryden and others are using, so valuable. It’s supplementing models-based findings, theory and speculation with real-world observations.
In 2009, the array of trans-Atlantic ocean-monitoring devices between the Bahamas and Morocco detected a sudden powering down of the AMOC. The 30 percent slowdown would eventually last a little longer than a year, before much of its vigor was restored.
Based in part on data from the AMOC slowdown of 2009 and 2010, a team of U.K.-based researchers, led by Bryden, concluded in a paper published in Ocean Science late last year that subsequent ocean temperature changes helped to create “severe winter conditions over northwestern Europe” and “contributed to the high intensity” of the Atlantic hurricane season in the summer of 2010.
More recently, other researchers, from the University of Arizona at Tucson and National Oceanic and Atmospheric Administration, linked that same AMOC slowdown with a spike of 5 inches in sea levels just north of New York City. The research was published in Nature Communications. “The extreme nature” of the rise in regional sea levels “suggests that such a significant downturn of the Atlantic overturning circulation is very unusual,” the scientists wrote, warning that such events could become more common in the future.
Findings dealing with the brief slowdown have been troubling so far, but it remains to be seen just how much can be gleaned from it.
“The 2009 to 2010 event was highly likely due to natural variability,” NOAA research scientist Tom Delworth said. “It’s important to note that this event was very short-lived and rapid. Projected future weakening of the AMOC in response to greenhouse gases would occur on a much longer timescale, and against a background of a much warmer climate.” | <urn:uuid:0121b29f-c119-4bef-8ef1-601d1e0b53a8> | 3.5 | 1,000 | Truncated | Science & Tech. | 38.809274 | 95,637,626 |
The homotopy Lie algebra and the holonomy representation
In this section the ground ring is an arbitrary field k of characteristic zero. Recall from §21(d) that the homotopy Lie algebra, L x- of a simply connected topological space X is the graded vector space, equipped with a Lie bracket defined via the Whitehead product in π*(X). In particular, (cf. Example 2, §21) each x ∈ L x determines the linear transformation adx :L x → L x, given by
KeywordsSpectral Sequence Finite Type Infinite Sequence Affine Space Rational Homology
Unable to display preview. Download preview PDF. | <urn:uuid:adf9fa37-e09b-4055-995d-98d8578d0d5c> | 2.53125 | 138 | Truncated | Science & Tech. | 43.70325 | 95,637,654 |
This movement causes a buildup of stress within the ice. Under enough stress, the ice cracks or buckles in a cataclysmic process that resembles the energy released in earthquakes. These continuous ice quakes result in open leads of water or mountainous ridges of broken, jumbled ice. These deformations, in turn, may have an effect on the thickness and durability of the arctic ice pack in the face of climate change.
University of Alaska Fairbanks researcher Jennifer Hutchings hopes that a better understanding of this complex process will help improve climate models and shed light on how sea ice behaved in the past and how it may change in the future.
Hutchings, a research associate at the UAF International Arctic Research Center, is chief scientist on a team of researchers that will spend the next two weeks at the U.S. Navy ice camp in the Beaufort Sea studying the relationship between ice movement, stress and the overall mass of sea ice.
The UAF-led expedition, which also includes lead researchers Cathleen Geiger and Chandra Kambhamettu of the University of Delaware and Jacqueline Richter-Menge of the U.S. Army Corps of Engineers’ Cold Regions Research and Engineering Laboratory, begins April 1. The field expedition is part of the Sea Ice Experiment: Dynamic Nature of the Arctic project, dubbed SEDNA, which is part of UAF’s collaborative International Polar Year research efforts.
Hutchings said the fieldwork will involve deploying buoys and other instruments to measure the movement and stress of the ice pack in the area around the field camp.
“We are going to use that information to validate the current generation of sea ice models,” Hutchings said. “We are trying to reduce the uncertainty of our prediction of arctic climate change.”
Ice deformation may have an effect on climate because open leads of water tend to add more heat and moisture to the atmosphere, which could reduce the overall amount of sea ice.
Conversely, if ice movement results in more ridges and thicker ice, the result could be a more durable arctic ice pack that is less vulnerable to seasonal melting.
The amount of sea ice is important to the overall understanding of climate change because it is thought to affect how much solar radiation, and hence heat, is reflected back into space. Sea ice is also thought to be an indicator of global temperature changes
The expedition also offers scientists a chance to share the field research experience with K-12 students through the National Science Foundation’s PolarTREC program, which links scientists and teachers for collaboration. Robert Harris, a high school teacher from Vermont, will join the researchers on the expedition and will relay the events and experiences of the camp to K-12 students via the Internet at www.polartrec.com/sedna-ice-camp/overview.
The SEDNA project is funded by a $1.4 million grant from the National Science Foundation. The project will also contribute to the lead International Polar Year project on the state of arctic sea ice.
NOTE TO EDITORS: Jennifer Hutchings will be departing for field camp on March 29, but will be available for interviews upon her return.
CONTACT: Jennifer Hutchings, IARC research associate, at (907) 474-7569 or via e-mail at email@example.com. Marmian Grimes, UAF public information officer, at (907) 474-7902 or via e-mail at firstname.lastname@example.org.
Abrupt cloud clearing events over southeast Atlantic Ocean are new piece in climate puzzle
23.07.2018 | University of Kansas
Global study of world's beaches shows threat to protected areas
19.07.2018 | NASA/Goddard Space Flight Center
A new manufacturing technique uses a process similar to newspaper printing to form smoother and more flexible metals for making ultrafast electronic devices.
The low-cost process, developed by Purdue University researchers, combines tools already used in industry for manufacturing metals on a large scale, but uses...
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
23.07.2018 | Health and Medicine
23.07.2018 | Earth Sciences
23.07.2018 | Science Education | <urn:uuid:50a7a690-49aa-4b6a-a885-8fce0decbbfb> | 3.6875 | 1,305 | Content Listing | Science & Tech. | 43.489805 | 95,637,679 |
( ) 2
VX -vr sine
membrane moves back and Torth an slmp...
each other but
ore A the
PE may Ef ohon DE main ore A thei...
work and Energg
hat is energy
ect) by a
done on L...
The ension force
pulling a box, for ecomele with a pope
What is the Universe made out
dark matter 2S (of
dark energy ...
the auteome of t...
This detailed and well structured Guide builds upon the Physics pri...
This Guide is an aid to understanding one of the essential ‘hard’ s...
Access over 10 million pages of study
documents for 1.3 million courses.
Join to view
So we can recommend you notes for your school.
Please enter below the email address you registered with and we will send you a link to reset your password.
Get notes from the top students in your class. | <urn:uuid:772d8f83-7849-4248-ad6c-000310696eef> | 2.515625 | 207 | Content Listing | Science & Tech. | 84.114038 | 95,637,694 |
When the electrons absorb em radiation, do they only absorb a specific frequency?
When they emmit the em radiation, do they emitt it the smae frequency they absorbed?
Turn on thread page Beta
exited electrons absorbing e.m light and emitting them? watch
- Thread Starter
- 28-03-2011 21:09
- 28-03-2011 21:19
How can they 'absorb' something and then emmit it?
I'm guessing they don't...
- 28-03-2011 22:26
Electrons will only absorb photons with the right amount of energy to move them up to a permitted energy level. Anything else will be ignored.
They can indeed emit photons with the same energy, but it is also possible to emit photons with a smaller or larger amount of energy, so long as the electron falls to another permitted energy level. This may be the same level is started off from, but it may be one further down (if it didn;t start off in its ground state) or one further up (if the absorbed photon enabled it to "leapfrog" over one or more levels on the way up).
And of course, all this talk of "energy" can be recast as "frequency" because of E = hf. | <urn:uuid:edf23488-abc7-460f-89c0-ef7f7c63d962> | 2.875 | 267 | Comment Section | Science & Tech. | 70.765419 | 95,637,696 |
TDDD34 Programming with Applications in Engineering
Figures, plots and graphs in Matlab
This document describes how to draw and plot in a separate figure window. The figure window frequently appear below other windows, be prepared to bring it to top manually.
Functions and operators
plot Plots (graphically) data in a separate figure window. plot3 Plots in 3D. axis Configures range and relative scale of the axes in the figure window. hold Decide if the next plot should keep or clear the contents of the figure window. (By default new plots erases any previous plots.) clf Clears the figure window. figure Opens a new figure window and focuses it. figure(x) Moves focus to the existing window x. semilogx Plot with logarithmic scale on x axis. semilogy Plot with logarithmic scale on y axis. loglog Plot with logarithmic scale on both axes. grid Draws a grid in the figure window. imagesc Draws colored squares in the figure window based on the contents of a matrix.
A lot of more interesting and useful details can be said of the above commands. You can for example plot with different colors, lines and sizes. Be prepared to use Matlabs built-in help command (try "help help"). When you know how to use the built-in help, use it on all above commands to take a quick look on what you can do.
Page responsible: Erik Nilsson
Last updated: 2012-08-07 | <urn:uuid:5f789251-9df9-4b39-ba82-79cd826650cf> | 3.25 | 317 | Documentation | Software Dev. | 55.315983 | 95,637,708 |
Hyperboloid of one sheet
conical surface in between
Hyperboloid of two sheets
In geometry, a hyperboloid of revolution, sometimes called circular hyperboloid, is a surface that may be generated by rotating a hyperbola around one of its principal axes. A hyperboloid is a surface that may be obtained from a hyperboloid of revolution by deforming it by means of directional scalings, or more generally, of an affine transformation.
A hyperboloid is a quadric surface, that is a surface that may be defined as the zero set of a polynomial of degree two in three variables. Among quadric surfaces, a hyperboloid is characterized by not being a cone or a cylinder, having a center of symmetry, and intersecting many planes into hyperbolas. A hyperboloid has also three pairwise perpendicular axes of symmetry, and three pairwise perpendicular planes of symmetry.
Given a hyperboloid, if one chooses a Cartesian coordinate system whose axes are axes of symmetry of the hyperboloid, and origin is the center of symmetry of the hyperboloid, then the hyperboloid may be defined by one of the two following equations:
Both of these surfaces are asymptotic to the cone of equation
One has an hyperboloid of revolution if and only if Otherwise, the axes are uniquely defined (up to the exchange of the x-axis and the y-axis.
There are two kinds of hyperboloids. In the first case (+1 in the right-hand side of the equation), one has a one-sheet hyperboloid, also called hyperbolic hyperboloid. It is a connected surface, which has a negative Gaussian curvature at every point. This implies that the tangent plane at any point intersects the hyperboloid at two lines, and thus that the one-sheet hyperboloid is a doubly ruled surface.
In the second case (-1 in the right-hand side of the equation), one has a two-sheet hyperboloid, also called elliptic hyperboloid. The surface has two connected components, and a positive Gaussian curvature at every point. Thus the surface is convex in the sense that the tangent plane at every point intersects the surface only in this point.
Animation of a hyperboloid of revolution
Cartesian coordinates for the hyperboloids can be defined, similar to spherical coordinates, keeping the azimuth angle ? ? [0, 2?), but changing inclination v into hyperbolic trigonometric functions:
One-surface hyperboloid: v ? (-∞, ∞)
Two-surface hyperboloid: v ? [0, ∞)
hyperboloid of one sheet: generation by a rotating hyperbola (top) and line (bottom: red or blue)
hyperboloid of one sheet: plane sections
Properties of a hyperboloid of one sheet
Lines on the surface
If the hyperboloid has the equation
then the lines
are contained in the surface.
In case of the hyperboloid is a surface of revolution and can be generated by rotating one of the two lines or , which are skew to the rotation axis (see picture). The more common generation of a hyperboloid of revolution is rotating a hyperbola around its semi-minor axis (see picture).
Remark: A hyperboloid of two sheets is projectively equivalent to a hyperbolic paraboloid.
For simplicity the plane sections of the unit hyperboloid with equation are considered. Because a hyperboloid in general position is an affine image of the unit hyperboloid, the result applies to the general case, too.
- A plane with a slope less than 1 (1 is the slope of the lines on the hyperboloid) intersects in an ellipse,
- A plane with a slope equal to 1 containing the origin intersects in a pair of parallel lines,
- A plane with a slope equal 1 not containing the origin intersects in a parabola,
- A tangential plane intersects in a pair of intersecting lines,
- A non-tangential plane with a slope greater than 1 intersects in a hyperbola.
Obviously, any one-sheet hyperboloid of revolution contains circles. This is also true, but less obvious, in the general case (see circular section).
hyperboloid of two sheets: generation by rotating a hyperbola
hyperboloid of two sheets: plane sections
Properties of a hyperboloid of two sheets
The hyperboloid of two sheets does not contain lines. The discussion of plane sections can be performed for the unit hyperboloid of two sheets with equation
which can be generated by a rotating hyperbola around one of its axes (the one that cuts the hyperbola)
- A plane with slope less than 1 (1 is the slope of the asymptotes of the generating hyperbola) intersects either in an ellipse or in a point or not at all,
- A plane with slope equal to 1 containing the origin (midpoint of the hyperboloid) does not intersect ,
- A plane with slope equal to 1 not containing the origin intersects in a parabola,
- A plane with slope greater than 1 intersects in a hyperbola.
Obviously, any two-sheet hyperboloid of revolution contains circles. This is also true, but less obvious, in the general case (see circular section).
Remark: A hyperboloid of two sheets is projectively equivalent to a sphere.
Common parametric representation
The following parametric representation includes hyperboloids of one sheet, two sheets, and their common boundary cone, each with the -axis as the axis of symmetry:
- For one obtains a hyperboloid of one sheet,
- For a hyperboloid of two sheets, and
- For a double cone.
One can obtain a parametric representation of a hyperboloid with a different coordinate axis as the axis of symmetry by shuffling the position of the term to the appropriate component in the equation above.
Symmetries of a hyperboloid
The hyperboloids with equations
- pointsymmetric to the origin,
- symmetric to the coordinate planes and
- rotational symmetric to the z-axis and symmetric to any plane containing the z-axis, in case of (hyperboloid of revolution).
On the curvature of a hyperboloid
Whereas the Gaussian curvature of a hyperboloid of one sheet is negative, that of a two-sheet hyperboloid is positive. In spite of its positive curvature, the hyperboloid of two sheets with another suitably chosen metric can also be used as a model for hyperbolic geometry.
More generally, an arbitrarily oriented hyperboloid, centered at v, is defined by the equation
where A is a matrix and x, v are vectors.
The eigenvectors of A define the principal directions of the hyperboloid and the eigenvalues of A are the reciprocals of the squares of the semi-axes: , and . The one-sheet hyperboloid has two positive eigenvalues and one negative eigenvalue. The two-sheet hyperboloid has one positive eigenvalue and two negative eigenvalues.
In more than three dimensions
Imaginary hyperboloids are frequently found in mathematics of higher dimensions. For example, in a pseudo-Euclidean space one has the use of a quadratic form:
When c is any constant, then the part of the space given by
is called a hyperboloid. The degenerate case corresponds to c = 0.
As an example, consider the following passage:
- ... the velocity vectors always lie on a surface which Minkowski calls a four-dimensional hyperboloid since, expressed in terms of purely real coordinates (y1, ..., y4), its equation is y2
1 + y2
2 + y2
3 - y2
4 = -1, analogous to the hyperboloid y2
1 + y2
2 - y2
3 = -1 of three-dimensional space.
However, the term quasi-sphere is also used in this context since the sphere and hyperboloid have some commonality (See § Relation to the sphere below).
One-sheeted hyperboloids are used in construction, with the structures called hyperboloid structures. A hyperboloid is a doubly ruled surface; thus, it can be built with straight steel beams, producing a strong structure at a lower cost than other methods. Examples include cooling towers, especially of power stations, and many other structures.
Water tower in France: hyperboloid of one sheet
Port tower in Kobe (Japan): hyperboloid of one sheet
Relation to the sphere
In 1853 William Rowan Hamilton published his Lectures on Quaternions which included presentation of biquaternions. The following passage from page 673 shows how Hamilton uses biquaternion algebra and vectors from quaternions to produce hyperboloids from the equation of a sphere:
- ... the equation of the unit sphere ρ2 + 1 = 0, and change the vector ρ to a bivector form, such as σ + τ . The equation of the sphere then breaks up into the system of the two following,
- σ2 − τ2 + 1 = 0, S.στ = 0;
- and suggests our considering σ and τ as two real and rectangular vectors, such that
- Tτ = (Tσ2 − 1 )1/2.
- Hence it is easy to infer that if we assume σ λ, where λ is a vector in a given position, the new real vector σ + τ will terminate on the surface of a double-sheeted and equilateral hyperboloid; and that if, on the other hand, we assume τ λ, then the locus of the extremity of the real vector σ + τ will be an equilateral but single-sheeted hyperboloid. The study of these two hyperboloids is, therefore, in this way connected very simply, through biquaternions, with the study of the sphere; ...
In this passage S is the operator giving the scalar part of a quaternion, and T is the "tensor", now called norm, of a quaternion.
A modern view of the unification of the sphere and hyperboloid uses the idea of a conic section as a slice of a quadratic form. Instead of a conical surface, one requires conical hypersurfaces in four-dimensional space with points p = (w, x, y, z) ∈ R4 determined by quadratic forms. First consider the conical hypersurface
- which is a hyperplane.
Then is the sphere with radius r. On the other hand, the conical hypersurface
- provides that is a hyperboloid.
In the theory of quadratic forms, a unit quasi-sphere is the subset of a quadratic space X consisting of the x ∈ X such that the quadratic norm of x is one.
- ^ CDKG: Computerunterstützte Darstellende und Konstruktive Geometrie (TU Darmstadt) (PDF; 3,4 MB), S. 116
- ^ CDKG: Computerunterstützte Darstellende und Konstruktive Geometrie (TU Darmstadt) (PDF; 3,4 MB), S. 122
- ^ Thomas Hawkins (2000) Emergence of the Theory of Lie Groups: an essay in the history of mathematics, 1869--1926, §9.3 "The Mathematization of Physics at Göttingen", see page 340, Springer ISBN 0-387-98963-3
- ^ Ian R. Porteous (1995) Clifford Algebras and the Classical Groups, pages 22, 24 & 106, Cambridge University Press ISBN 0-521-55177-3 | <urn:uuid:a639d54b-8f87-4f0f-b935-2d1104c6049f> | 3.796875 | 2,557 | Knowledge Article | Science & Tech. | 35.531721 | 95,637,712 |
Some Points of Logic
Before You Get Started. We have already used phrases like for all, there exists, and, or, if... then, etc. What exactly do these mean? How would the meaning of a statement such as Axiom 1.4 change if we switched the order of some of these phrases? We will also need to express the negations of mathematical statements. Think about what the negation of an and statement should look like; for example, what are the negations of the statements “John and Mary like cookies” or “there exist positive integers that are not prime”?
KeywordsNormal Subgroup Mathematical Statement Philosophical Question Weekly Reminder Student Union
Unable to display preview. Download preview PDF. | <urn:uuid:19520295-4c64-494f-a02b-a3bc28f50e0f> | 3.75 | 153 | Truncated | Science & Tech. | 50.255658 | 95,637,717 |
Thanks in part to support from NASA and the National Science Foundation, scientists have produced the first-ever detailed maps of bedrock beneath glaciers in Greenland and Antarctica. This new data will help researchers better project future changes to glaciers and ice sheets, and ultimately, sea level.
Researchers at the Center for Remote Sensing of Ice Sheets, or CReSIS, at the University of Kansas in Lawrence, Kansas, recently built detailed maps of the terrain beneath Greenland’s Jakobshavn Glacier and Byrd Glacier in Antarctica.
The results of this study were published in the September issue of the Journal of Glaciology. CReSIS is a major participant in NASA’s Operation IceBridge, a NASA airborne science mission aimed at studying Arctic and Antarctica land and sea ice.
CReSIS researchers used computer software to process and analyze data collected during field campaigns unrelated to IceBridge that were conducted in cooperation with NASA and NSF in 2008 and 2011 to build maps of the two glaciers.
These data were from an ice-penetrating radar instrument known as the Multichannel Coherent Depth Sounder / Imager, or MCoRDS / I, which is similar to the instrument IceBridge has used since 2009. Bed topography data are vital for computer models used to project future changes to ice sheets and their contribution to sea level rise. “Without bed topography you cannot build a decent ice sheet model,” said CReSIS director Prasad Gogineni.
Jakobshavn Glacier is of interest because it is the fastest-moving glacier in the world and drains about 7.5 percent of the Greenland Ice Sheet. Having a map of Jakobshavn’s bed has been a long-time goal of glaciologists. Byrd Glacier is also moving faster than average, but unlike many other glaciers, has been sounded in the past. Researchers mapped a previously unknown trench beneath Byrd Glacier and found that depth measurements from the 1970s were off by as much as a half mile in some places.
Ice-penetrating radar is one method for mapping bedrock topography. The instrument sends down radar waves, which reflect off of the ice surface, layers inside the ice sheet and bedrock back to the instrument, giving researchers a three-dimensional view. Ice-penetrating radar data from IceBridge flights helped build maps of Greenland and Antarctica’s bedrock and were even used to discover a large canyon beneath the ice in northern Greenland.
Imaging rock beneath glaciers like Jakobshavn is important, but more difficult than mapping the ice sheet interior. The relatively warm ice and rough surfaces of outlet glaciers weaken and scatter radar signals, making the bed difficult to detect. To overcome these challenges, CReSIS used a sensitive radar instrument with a large antenna array and used several processing techniques to remove interference and build a view of sub-ice bedrock. “We showed that we have the technology to map beds,” said Gogineni.
The MCoRDS / I instrument can be traced back to an early ice-penetrating radar CReSIS designed and built in the mid-90s in cooperation with NASA and NSF. In the two decades since then CReSIS has refined this instrument and has flown on NASA aircraft and alongside NASA instruments.
Researchers continue to improve instrument hardware and data processing and are looking ahead to mapping more glaciers in the future, which will likely involve small, unmanned aerial vehicles. “Improving ice sheet models means we need even finer resolution,” Gogineni said. “To do this we need lines flown much closer together, which small UAVs would be well suited for.”
For more information on NASA's Operation Ice Bridge, visit:
For more information about the Center for Remote Sensing of Ice Sheets, visit:
George Hale | Eurek Alert!
New research calculates capacity of North American forests to sequester carbon
16.07.2018 | University of California - Santa Cruz
Scientists discover Earth's youngest banded iron formation in western China
12.07.2018 | University of Alberta
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
18.07.2018 | Life Sciences
18.07.2018 | Materials Sciences
18.07.2018 | Health and Medicine | <urn:uuid:1d0c8843-586b-4140-9039-8fe325d72485> | 4.1875 | 1,430 | Content Listing | Science & Tech. | 39.062295 | 95,637,720 |
The coloured track (left colour scale) west of Reunion is the calculated movement of the Reunion hotspot. The black lines with yellow circles and the red circle indicate the corresponding calculated track on the African plate and the Indian plate, respectively. The numbers in the circles are ages in millions of years. The areas with topography just below the sea surface are now regarded as continental fragments.
Steinberger. "On the other hand, we were able to show that the continent fragments continued to wander almost exactly over the Reunion plume, which explains how they were covered by volcanic rock." So what was previously interpreted only as the trail of the Reunion hotspot, are continental fragments which were previously not recognized as such because they were covered by the volcanic rocks of the Reunion plume. It therefore appears that such micro-continents in the ocean occur more frequently than previously thought.
Torsvik, T.H., Amundsen, H., Hartz, E.H., Corfu, F., Kusznir, N., Gaina, C., Doubrovine, P.V., Steinberger B., Ashwal, L.D. & Jamtveit, B., „A Precambrian microcontinent in the Indian Ocean", Nature Geoscience, Vol. 6, doi:10.1038/NGEO1736.
F. Ossing | EurekAlert!
Global study of world's beaches shows threat to protected areas
19.07.2018 | NASA/Goddard Space Flight Center
NSF-supported researchers to present new results on hurricanes and other extreme events
19.07.2018 | National Science Foundation
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
19.07.2018 | Materials Sciences
19.07.2018 | Earth Sciences
19.07.2018 | Life Sciences | <urn:uuid:5f235899-90ee-4705-a8f0-c64a14fb78a3> | 3.125 | 920 | Content Listing | Science & Tech. | 46.479784 | 95,637,734 |
Astronomers have made use of ESO’s Very Large Telescope to detect for the first time in the ultraviolet the carbon monoxide molecule in a galaxy located almost 11 billion light-years away, a feat that had remained elusive for 25 years. This detection allows them to obtain the most precise measurement of the cosmic temperature at such a remote epoch.
The team of astronomers aimed the UVES spectrograph on ESO’s VLT for more than 8 hours at a well-hidden galaxy whose light has taken almost 11 billion years to reach us, that is about 80% of the age of the Universe.
The only way this galaxy can be seen is through the imprint its interstellar gas leaves on the spectrum of an even more remote quasar . “Quasars are here only used as a beacon in the very distant Universe. Interstellar clouds of gas in galaxies, located between the quasars and us on the same line of sight, absorb parts of the light emitted by the quasars. The resulting spectrum consequently presents dark ‘valleys’ that can be attributed to well-known elements and possibly molecules,” explains Raghunathan Srianand (Pune, India), who led the team making the observations.
Thanks to the power of the VLT and a very careful selection of the target - the target was selected among about ten thousands quasars - the team was able to discover the presence of normal and deuterated molecular hydrogen (H2, HD) and carbon monoxide (CO) molecules in the interstellar medium of this remote galaxy. “This is the first time that these three molecules have been detected in absorption in front of a quasar, a detection that has remained elusive for more than a quarter century,” says Cédric Ledoux (ESO), member of the team.
The same team had already broken the record for the most distant detection of molecular hydrogen in a galaxy that we see as it was when the Universe was less than 1.5 billion years old (see ESO 16/06).
The interstellar gas is the reservoir from which stars form and, as such, is an important component of galaxies. Furthermore, because the formation and the state of molecules are very sensitive to the physical conditions of the gas, which in turn depend on the rate at which stars are formed and their influence, the detailed study of the chemistry of the interstellar medium is an important tool to understand how galaxies form.
Based on their observations, the astronomers showed that the physical conditions prevailing in the interstellar gas in this remote galaxy are similar to what is seen in our Galaxy, the Milky Way.
But most importantly, the team was able to measure with the best ever precision the temperature of the cosmic background radiation in the remote Universe . “Unlike other methods, measuring the temperature of the cosmic background using the CO molecule involves very few assumptions,” declares co-author Pasquier Noterdaeme.
If the Universe was formed in a ‘Big Bang’, as most astrophysicists infer, the glow of this primeval fireball should have been warmer in the past. This is exactly what is found by the new measurements. “Given the current measured temperature of 2.725 K, one would expect that the temperature 11 billion years ago was about 9.3 K,” says co-author Patrick Petitjean. “Our unique set of VLT observations allows us to deduce a temperature of 9.15 K, plus or minus 0.7 K, in excellent agreement with the theory.”
“We believe our analysis pioneers interstellar chemistry studies at high redshift and demonstrates that it is possible, together with the detection of other molecules such as HD or CH, to use interstellar chemistry to tackle important cosmological issues,” adds Srianand.
Notes The team is composed of Raghunathan Srianand?(IUCAA,?Pune, India), Pasquier Noterdaeme and Cédric Ledoux (ESO), and Patrick Petitjean (IAP, France). The same team already made the first measurement of the temperature of the cosmic microwave background radiation, at a time when the Universe was only about 2.5 billion years old, also using UVES on the VLT (see ESO 27/00). At that time, they could only measure a temperature in the range between 6 and 14 K.
One of the fundamental predictions of the Hot Big Bang theory for the creation of the Universe is the existence of the Cosmic Microwave Background Radiation (CMBR). This relic radiation of the primeval fireball was discovered in 1964 by means of radio observations by American physicists Arno A. Penzias and Robert W. Wilson, who were rewarded with the Nobel Prize in 1978. Precision measurements by the COBE and WMAP satellites later showed that this ancient radiation fills the Universe, with a present-day temperature of slightly less than 3 degrees above absolute zero (2.725 K [Kelvin], or -270.4 °C). A particular prediction of the Big Bang theory is that the Universe cools when expanding, the temperature scaling with the dilution factor of the Universe (1 + redshift). At the redshift of the galaxy (2.41837), one would thus expect a temperature of 2.725 x (1 + 2.41837) = 9.315 K or -263.835 degree Celsius.
Henri Boffin | alfa
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:ffd04d5e-416c-4e73-bf25-08bcdb61f93d> | 3.53125 | 1,707 | Content Listing | Science & Tech. | 44.906573 | 95,637,740 |
Washington: In a pioneering feat, researchers have shown that an inexpensive metal-free catalyst can help us reduce the cost of generating clean energy from polymer electrolyte membrane (PEM) cells.
PEM cells are a type of fuel cell being developed for transport applications as well as for stationary and portable fuel cell applications.
Such a low-cost catalyst can perform the same task earlier carried out by costly metal catalysts.
For nearly half a century, scientists have been trying to replace precious metal catalysts in fuel cells.
"The findings will make low-cost catalysts commercially available, which could, in turn, reduce the cost to generate clean energy from PEM fuel cells," the authors said.
Such cells are mostly used in cars and stationary power plants.
"It is a major breakthrough for commercialisation. This definitely should move the field forward," said Liming Dai, professor of macromolecular science and engineering at the Case Western Reserve University in the US.
The key to the new catalyst is its rationally-designed porous structure.
The researchers mixed sheets of nitrogen-doped graphene, a single-atom thick, with carbon nanotubes and carbon black particles in solution, then freeze-dried them into composite sheets and hardened them.
A fuel cell converts chemical energy into electrical energy by removing electrons from a fuel, such as hydrogen, at the cell's anode, or positive electrode.
This creates current.
Testing showed the porous catalyst performs better and is more durable than the iron-based catalyst.
Efforts are on to fine-tune the materials and structure as well as investigate the use of non-metal catalysts in more areas of clean energy.
The study was published in the journal Science Advances. | <urn:uuid:223005db-84c8-4528-bd05-68182e374ac9> | 3.8125 | 360 | News Article | Science & Tech. | 34.399762 | 95,637,748 |
A laser beam with a different irradiance profile may have favorable scintillation and diffraction characteristics, which are important qualities in the area of optical wireless communication. The propagation in random media (atmosphere) of a laser beam with an annular, donut-shaped, irradiance cross section was examined. Annular beams are created by unstable optical resonators, which are used as resonant cavities in high power lasers, and by beam expanders that consist of telescopes where the second mirror obstruct the central portion of the circular aperture. The annular beam was modeled as the difference of two collimated Gaussian beams, with different spot sizes. Diffraction and scintillation characteristics of the annular beam, for horizontal near ground propagation (i.e. constant refractive-index structure parameter Cn2), were compared to one collimated and one focused Gaussian beam. The Rytov approximation was used to calculate the on-axis scintillation index in weak atmospheric turbulence for both the annular and the Gaussian beams. The extended Huygens-Fresnel integral was solved to obtain the mean irradiance, from which the fraction of power in half aperture diameter was calculated. | <urn:uuid:5d2877dd-2aad-4a14-9e3b-da18d9d189cd> | 2.96875 | 243 | Academic Writing | Science & Tech. | 14.515 | 95,637,757 |
Sedimentary and Diagenetic Features in the Sulfide-Bearing Sedimentary Dikes and Strata of Lower Ordovician Dolomites, Decaturville, Missouri, U.S.A.
Additional studies of the Decaturville cryptovolcanic structure in western Missouri, USA, in a new exposure, has revealed additional information on distribution of sulfide minerals and sedimentary features associated with this structure.
The new roadcut exposes a nearly complete section of the Lower Ordovician Jefferson City and Cotter dolomites, permitting detailed examination of features about two km from the center of the structure along the inner margin of the ring fault which surrounds the structure.
The formations consist almost entirely of dolomite with some sandstone, shale, and chert. Sandstones, in beds from 3 to 300 cm thick in this area, and breccias are interpreted to mean a closer proximity to the source area than other exposures in the Ozarks. In addition, the beds have a cyclic arrangement, whose pattern suggests oscillation from very shallow marine conditions to subaerial exposure. This feature is also not apparent in exposure in the Ozarks although poorer exposures may have obscured necessary details in other places.
Sulfides occur both as stratiform blebs in a few layers and more particularly within the matrix and some breccia clasts in sedimentary dikes which occur in the upper part of the section. They make about 1% of the volume of the dike, sufficient to give the dikes a gray to dark gray color.
The sulfides of the dikes consist of pyrite, marcasite, some galena and sphalerite. The sulfides occur in the following forms: (1) pyrite and marcasite spheres, containing framboids, (2) fragments of pyrite-marcasite with porous pyrite framboids, (3) isolated pyrite framboids, (4) minute fragments of fine-grained marcasite, pyrite or mixed pyrite-marcasite fragments, (5) fragments of colloform pyrite, (6) limonite-coated colloform pyrite fragments, and (7) fragments of sphalerite(?). Each of these occurrences is illustrated and a paragenetic sequence for these is given.
It is postulated that the sulfides were transported into the dikes as detritals along with detrital sand and clay from source beds which can be defined for most dikes.
KeywordsIron Sulfide Pyrite Framboids Diagenetic Feature Breccia Clast Argillaceous Sandstone
Unable to display preview. Download preview PDF.
- Beales FW, Lozej GP (1975) Ordovician tidalites in unmetamorphosed sedimentary fill of the Brent meteorite crater, Ontario. In: Ginsburg RN (ed) Tidal deposits. Springer, Berlin Heidelberg New York, pp 315–323Google Scholar
- Berner RA (1981) Authigenic mineral formation resulting from organic matter decomposition in modern sediments. Fortschr Mineral 59: 117–135Google Scholar
- Buerger MJ (1934) The pyrite-marcasite relation. Am Mineral 19: 37–61Google Scholar
- Craig JR, Scott SD (1974) Sulfide phase equilibria. In: Ribbe PH (ed) Sulfide mineralogy. Mineral Soc Am Short Course Notes, vol 1:CS1–CS110Google Scholar
- Cressman ER (1981) Surface geology of the Jeptha Knob cryptoexplosion structure, Shelby County, Kentucky. US Geol Sury Prof Pap 1151-B: 16Google Scholar
- Dake CL (1921) The problem of the St Peter Sandstone. University of Missouri-Sch of Mines and Metal Tech Ser: 6 No 1Google Scholar
- Fenton CL, Fenton MA (1937) Belt series of the north: stratigraphy, sedimentation, paleontology. Geol Soc Am Bull 48: 1837–1970Google Scholar
- Gansser A (1960) Über Schlammvulkane und Salzdome. Vierteljahresschrift Naturforsch Ges Zürich 105: 1–46Google Scholar
- Gephard PL (1973–1974) Origin of dolomite and distribution of stromatolites of the Jefferson City Formation, Cole County, Missouri. Trans Mo Acad Sci 7–8: 189–193Google Scholar
- Nichols CE (1977) Geology of the southern half of the Stoutland, Missouri Quadrangle. University Missouri, Rolla, PhD DissGoogle Scholar
- Offield TW, Pohn HA (1979) Geology of the Decaturville impact structure, Missouri. US Geol Sury Prof Pap 1042: 1–48Google Scholar
- Shrock RR (1948) Sequence in layered rocks. McGraw-Hill, New York, 507 pGoogle Scholar
- Wilshire HG, Offield TW, Howard KA, Cummings D (1972) Geology of the Sierra Madera cryptoexplosion structure, Pecos County, Texas. US Geol Sury Prof Pap 599-H: 42Google Scholar
- Zimmermann RA (1976) The Cambro-Ordovician fossil mud volcano of Decaturville, Missouri. Proc Vulcanism, vol 3. Int congr on thermal waters, geothermal energy and vulcanism of the Mediterranean area, Athens, Greece, pp 265–279Google Scholar
- Zimmermann RA, Amstutz GC (1965) The polygonal structure at Decaturville, Missouri: new tectonic observations. Neues Jahrb Mineral Monatsh 1965: 288–307Google Scholar
- Zimmermann RA, Amstutz GC (1972) The Decaturville sulfide breccia — a Cambro-Ordovician mud volcanoe. Chemie Erde 31: 253–274Google Scholar
- Zimmermann RA, Amstutz GC (1973) Intergrowth and crystallization features in the Cambrian mud volcanoe of Decaturville, Missouri, USA. In: Amstutz GC, Bernard AJ (eds) Ores in sediments (Int Union of Geol Sci Ser A, No 3 ). Springer, Berlin Heidelberg New York, pp 339–350Google Scholar
- Zimmermann RA, Amstutz GC (1979) Tectonic features in the polygonal structure of Decaturville, west-central Missouri. Neues Jahrb Mineral Monatsh 1979: 443–470Google Scholar | <urn:uuid:a7acc37b-de4b-4705-9b1b-0d44925ab17f> | 2.640625 | 1,390 | Academic Writing | Science & Tech. | 33.026636 | 95,637,777 |
The reason apparently is supersonic winds, perhaps as strong as 9,000 miles an hour, that constantly churn the planets' atmospheres and keep temperatures on the dark side from plunging.
The planets, gas giants similar in size to Jupiter, were discovered in the last decade orbiting stars about the same size as our sun and less than 150 light years from Earth. All of them orbit within about 5 million miles of their stars, far less than Mercury's distance from our sun.
Astronomers have wondered whether planets orbiting so close to their stars but with one side in constant daylight and the other permanently dark would exhibit sharp temperature differences between the day side and the night side. For the three planets in this study, the temperatures appear to be constant, likely because of the strong winds that mix the atmosphere planetwide, said Eric Agol, a University of Washington assistant professor of astronomy and co-author of a poster presenting the findings today at the American Astronomical Society national meeting in Seattle.
"We can't say for sure that we've ruled out significant day-night temperature differences, but it seems unlikely there is a very big contrast based on our measurements and what we know about these systems," said Agol, who is lead scientist for a project using the Spitzer Space Telescope to measure the temperature properties of extrasolar planets.
Agol and colleagues Nicolas Cowan, a UW astronomy doctoral student and lead author of the poster, and David Charbonneau of the Harvard-Smithsonian Center for Astrophysics measured infrared light from each of the planetary systems at eight different positions in their orbits in late 2005. They measured the thermal brightness of the systems when the planets' day sides faced the Earth, when the night sides faced the Earth and at various phases in between. They detected no infrared brightness variations in any of the systems, suggesting there are not big differences in temperatures on the day and night sides.
Instead the planets appear to have a fairly uniform temperature of about 925 degrees Celsius, or about 1700 degrees Fahrenheit.
"If heat from the parent star is carried to the dark side, then the overall temperature would be lowered somewhat because the heat is being distributed across the planet," Agol said. "Some theorists believe that supersonic winds are responsible for recirculating the heat."
Measuring the planets' temperatures is a painstaking process because a planet's radiation is drowned out by the light from its host star. Even when a planet goes behind the parent star and disappears completely from view, the decline in light from the entire system is almost imperceptible, on the order of 0.25 percent, Agol said. Making the observations requires precise calibration and light measurements.
The three planets are 51 Pegasi, about 50 light years from our sun, HD179949b about 100 light years distant, and HD209458b about 147 light years away. A light year is about 5.88 trillion miles. In 1995, 51 Pegasi became the first planet orbiting another star to be discovered. Since then numerous planets – gas giants the mass of Jupiter or larger – have been observed from Earth. Most orbit very close to their stars. A common theory is that they formed far away from their stars, perhaps in about the same position as Jupiter is to our sun, and then migrated close to their stars. Their distance makes it difficult to gather much direct data about the planets.
To date no Earth-sized planets have been reported orbiting other stars like our sun.
Agol noted that the planets probably have the same side always facing the star because they are so close to their parent stars. The effect is the same as the Earth has on the moon, which has had its rotation slowed so much by Earth's gravity that the same side always faces Earth.
"These planets are so close to their host stars that the tidal forces are enormous, a few thousand times as strong as on Earth," he said. "The tides are so strong and form a bulge that distorts the planet so much that the orbit is slowed by the star's tug on the tidal bulge."
The Spitzer telescope is managed by NASA's Jet Propulsion Laboratory in Pasadena, Calif., and its science operations are conducted at the California Institute of Technology.
Vince Stricherz | EurekAlert!
First evidence on the source of extragalactic particles
13.07.2018 | Technische Universität München
Simpler interferometer can fine tune even the quickest pulses of light
12.07.2018 | University of Rochester
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
13.07.2018 | Event News
13.07.2018 | Materials Sciences
13.07.2018 | Life Sciences | <urn:uuid:cd14a5e1-7807-4b8b-b450-f71ec95a22b3> | 4 | 1,503 | Content Listing | Science & Tech. | 44.513178 | 95,637,782 |
以下内容由机器翻译生成。如果您觉得可读性不好, 请阅读原文或 点击这里.
A team of neuroscientists at UCLA yesterday unveiled the results of an experiment involving snail brains that could radically change our understanding of how memories work. That is, if the rest of the scientific community can suspend its disbelief long enough to give the group’s ideas serious consideration.
The scientists, led by Dr. David Glanzman, extracted RNA from the brains of Aplysia – sea slugs – and then injected it into the brain of another Aplysia. According to the researchers’ 白皮书, this resulted in the transfer of memories from one creature to another:
Here, it is demonstrated that the memory for long-term sensitization in the marine mollusk Aplysia can be successfully transferred by injecting RNA from sensitized into naïve animals.
Moreover, a specific cellular alteration that underlies sensitization in Aplysia, sensory neuron hyperexcitability, can be reproduced by exposing sensory neurons in vitro to RNA from trained animals. The results provide support for a nonsynaptic, epigenetic model of memory storage in Aplysia.
CNBC 喜欢 TNW 会议那么多
The experiment involved training, or sensitizing, Aplysia by shocking them. When an innocent Aplysia gets an electrical jolt for the first time it retracts its sensitive parts for a few seconds. But after a few shocks, once it becomes sensitized to the situation, the length of time it protects itself increases to minutes.
The researchers extracted the RNA of Aplysia which had become sensitized to the treatment and injected it into innocent Aplysia. The results were that the creatures who’d never experienced shock reacted as though they were sensitized when the scientists shocked them for the first time.
Glanzman and his team submit that this indicates memories can been transferred through RNA.
This, however, stands in opposition to longstanding notions of how brains form memories — through the formation of strong synaptic connections between neurons. Though this study isn’t the first to suggest otherwise.
It all started in the 60s when an eccentric professor at the University of Michigan, Dr. James V. McConnell, started grinding up tapeworms and feeding them to other tapeworms. He believed that the recipient cannibal worms would gain the knowledge held by the deceased.
Incredibly enough his results indicated he was right. Evidence from his study (and others since) have shown there may be some sort of transference of sensitization between the worms.
Unfortunately for McConnell his work was often ridiculed and refuted. Some scientists said his results weren’t reproducible, and others just said he was a quack. This, perhaps, is partially due to his odd sense of humor.
McConnell, a man of some wealth, created his own scientific journal called “The Worm Runners Digest.” The digest was a combination of legitimate scientific research and satire. On the one hand it published real papers such as the one that showed the results of his cannibal tapeworm experiment. But on the other it published papers that were meant as jokes, such as one on how strong an evening gown’s shoulder straps are.
It was easy for scientists and peers to dismiss McConnell’s work outright. Not only did it raise ethical questions, but the science was so radical that many refused to even consider its merit at all. Plus, his satire showed he wasn’t a very serious scientist — harumph.
His work was received so poorly by the scientific community that it became popularized, not for its science, but as a cautionary tale about making outlandish claims.
His reputation/infamy became so great that in 1985 a former student at the University of Michigan (who may have never actually crossed paths with McConnell while he was teaching) named Ted Kaczynski – also known as The Unabomber – mailed him a package-bomb which exploded, resulting in injury to McConnell and a research assistant.
Experts believe Kaczynski was triggered by McConnell’s claims that people would one day develop their personalities and skills through the ingestion of specialty chemicals.
McConnell passed away in 1990, decades before his work would be validated – at least partially.
Another neurosurgeon, Michael Levin, continued McConnell’s work with worms and published a paper in 2013 which vindicated many of McConnell’s ideas about how the creatures’ memory works.
And that brings us full circle to now where, less than 24 hours after publishing, Glanzman finds his work being dismissed outright by some, despite its incredible implications.
A report from STAT indicates as much:
“If he’s right, this would be absolutely earth-shattering,” said Tomás Ryan, an assistant professor at Trinity College Dublin, whose lab hunts for engrams, or the physical traces of memory. “But I don’t think it’s right.”
So what would it mean if Glanzman’s team is right? If memories aren’t stored in synapses, but instead are contained in the nuclei of certain brain cells, it would theoretically be possible to “package” memories and inject them on demand. At least in worms and snails;most humans have brains far too complex to make any kind of assumptions that this work will be meaningful beyond slimy things.
Whether or not McConnell, Levin, and Glanzman were/are pulling the right thread remains to be seen, but how our brains form memories has become one of the longest lingering biological mysteries in science.
The fact that we still haven’t figured out how worms and snails manage to remember what little goes on their brains shows we have a long way to go in cracking how memory works. Maybe now is the right time to seriously reconsider theories dismissed over half a century ago. | <urn:uuid:6ad995ce-9b07-4581-bef8-f3b0f2541f30> | 3.5625 | 1,296 | News Article | Science & Tech. | 43.707129 | 95,637,788 |
Learn Objective C programming with the best free online courses and tutorials for beginners and advanced learners aggregated from Udemy, Edx, Skillshare, Coursera, Udacity, Treehouse, YouTube and other MOOCs .
Create your own awesome 3D map app in such an easy way!
Develop a Memory Puzzle App for iOS with Objective-C
Developing an iOS Slifing Puzzle Game with XCode and Objective-C
A 10 video-tutorial series that takes absolute beginners with no iOS development experience and teaches them the basics. - Free Course
Guía para aprender los fundamentos básicos de Swift en base a los conocidos de Objective-C - Free Course
A complete iOS app development using XCode, Firebase and Objective-C - Free Course
Explore and Follow course collections.
Don't have an account? | <urn:uuid:e4bfbdce-91ea-45a0-84a5-9f55e29504db> | 2.671875 | 179 | Content Listing | Software Dev. | 26.108161 | 95,637,811 |
North America's freshwater mussels of the family Unionidae
are extremely diverse, with approximately 300 species found throughout its waters (Williams et al.
Descriptions of some of the glochidia of the Unionidae
The superfamily Unionoidea is divided into two families, Unionidae
It was in Alabama where I was first introduced to the biology of freshwater mussels in the family Unionidae
(translates into pearl animals).
Influence of aluminum and protons on the electrolyte homeostasis in the Unionidae
Anodontaanatina and Uniopictorum.
Freshwater mussels from Upper Triassic Newark Supergroup of Atlantic coast rift-basin lakes were interpreted to belong to Mulleriidae (was Mycetopodidae; Mycetopoda), Hyriidae (Diplodon), and Unionidae
(Anoplophora, Unio) by Pilsbry (4,5).
This manuscript summarizes the findings of a survey for freshwater mussels of the family Unionidae
(hereafter, simply referred to as ''mussels") in selected streams of the Sabine National Forest (SNF) adjacent to Toledo Bend Reservoir in East Texas (Figure 1).
Remarks on the Unionidae
of Nebraska Territory, etc.
Large molluscs (Dreissena, Unionidae
, and Viviparus) were fixed separately and were not included in the total figures of macrozoobenthos abundance and biomass due to their much bigger individual weight compared with all other animals.
Mackie, Impact of the Zebra Mussel, Dreissena polymorpha, on Populations of Unionidae
(Bivalvia) in Lake St.
Primary consumers were pooled to order, producing nine general taxonomic/habitat classes: Unionidae
, Amphipoda, Trichoptera, tadpoles, Ephemeroptera, shallow zooplankton (0-3 m), deep zooplankton (10-12 m), Chironomidae (profundal), and miscellaneous littoral (littoral primary consumers collected from [less than]3 lakes).
is the minimum estimate for this split and it is possible that the divergence of the M and F lineages observed in Pyganodon and Fusconaia predate the divergence of the Unionidae
from other freshwater mussel families (e. | <urn:uuid:5d54a7ff-ae15-4f6a-9ec7-f7a12f0cc34b> | 3.171875 | 504 | Knowledge Article | Science & Tech. | -0.633479 | 95,637,812 |
Students record and interpret information about weather patterns and draw conclusions about how weather contributes to climate. They use their knowledge of weather to predict what the weather would be like in different climate zones. They identify three different climate zones in Australia – Tropical, Temperate, Desert and identify places within the zones. Students use an image to identify the effect of landforms on climate. The geographical tools included in this lesson are mapping, graphs and statistics, and visual representation.
What is the difference between climate and weather?
ACHASSK068, ACHASSI056, ACHASSI054, ACHASSI053
VCGGC074, VCGGK076, VCGGK081 | <urn:uuid:c567eea7-9537-4bc9-9d16-fa21f65ae35e> | 3.734375 | 146 | Content Listing | Science & Tech. | 25.333333 | 95,637,863 |
Global biodiversity is plummeting while biologists are fighting to keep score and reliable monitoring of threatened animals remains a major challenge. The biologist toolset has changed little on this area for a hundred years - still relying on expensive expert surveys basically finding and counting the animals.
However, this situation is now set to change according to a recent study by researchers at the Natural History Museum of Denmark published as a cover story in the acclaimed scientific journal Molecular Ecology. The results of the study show that a new method can be used to monitor rare and threatened animal species from DNA traces in their freshwater environments.
The development of the innovative DNA species monitoring was accomplished by PhD student Philip Francis Thomsen and Master's students Jos Kielgast and Lars L. Iversen at Centre for GeoGenetics headed by professor Eske Willerslev.
"We have shown that the DNA detection method works on a wide range of different rare species living in freshwater - they all leave DNA traces in their environment which can be detected in even very small water samples from their habitat. In the water samples we find DNA from animals as different as an otter and a dragonfly," says Philip Francis Thomsen.
By studying the fauna of one hundred different lakes and streams in Europe with both conventional methods - counting individuals - and the new DNA-based method the research team documents that DNA detection is effective even in populations where the animals are extremely rare. The study also shows that there is a clear correlation between the amount of DNA in the environment and the density of individuals meaning that the DNA detection method can even be used to estimate population sizes. This is crucial in the monitoring of rare animals, where one often wants to know whether the population is large or small.
"The UN has agreed to halt the decline of biodiversity, but a prerequisite to do so is that we are capable of properly documenting the status of threatened species. Our new approach is a huge step forward making it cheaper and faster to monitor the endangered species, and thus prioritise efforts to the benefit of biodiversity at a broad scale," says Jos Kielgast.
The researchers have documented that DNA traces of animals are nearly ubiquitous in the freshwater environment and, as a proof-of-concept, these findings may have wider implications reaching disciplines far beyond threatened species monitoring. With DNA sequencing technology advancing at rapidly dropping costs, environmental DNA research is set to change from being merely a scientific curiosity to become an important tool in applied biology. It is for example conceivable that fishing quota may in the future be based on DNA traces rather than fish catches.
PhD student, Philip Francis Thomsen (tel. 45-27142046)
Master's thesis student, Jos Kielgast (tel. 45-28492128), skypename: jos_kielgast
Philip Francis Thomsen | EurekAlert!
Upcycling of PET Bottles: New Ideas for Resource Cycles in Germany
25.06.2018 | Fraunhofer-Institut für Betriebsfestigkeit und Systemzuverlässigkeit LBF
Dry landscapes can increase disease transmission
20.06.2018 | Forschungsverbund Berlin e.V.
A new manufacturing technique uses a process similar to newspaper printing to form smoother and more flexible metals for making ultrafast electronic devices.
The low-cost process, developed by Purdue University researchers, combines tools already used in industry for manufacturing metals on a large scale, but uses...
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
20.07.2018 | Power and Electrical Engineering
20.07.2018 | Information Technology
20.07.2018 | Materials Sciences | <urn:uuid:a09eef3a-f54b-4df9-baad-ecd6fb8b7612> | 4.03125 | 1,178 | Content Listing | Science & Tech. | 36.114732 | 95,637,870 |
|C Sharp Programming is a featured book on Wikibooks because it contains substantial content, it is well-formatted, and the Wikibooks community has decided to feature it on the main page or in other places. Please continue to improve it and thanks for the great work so far! You can edit its advertisement template.|
C# (pronounced "See Sharp") is a multi-purpose computer programming language suitable for a wide variety of development needs. This Wikibook introduces C# language fundamentals and covers a variety of the base class libraries (BCL) provided by the Microsoft .NET Framework.
- Main introduction: C Sharp Programming/Foreword
Although C# is derived from the C programming language, it introduces some unique and powerful features, such as delegates (which can be viewed as type-safe function pointers) and lambda expressions which introduce elements of functional programming languages, as well as a simpler single class inheritance model (than C++) and, for those of you with experience in "C-like" languages, a very familiar syntax that may help beginners become proficient faster than its predecessors. Similar to Java, it is object-oriented, comes with an extensive class library, and supports exception handling, multiple types of polymorphism, and separation of interfaces from implementations. Those features, combined with its powerful development tools, multi-platform support, and generics, make C# a good choice for many types of software development projects: rapid application development projects, projects implemented by individuals or large or small teams, Internet applications, and projects with strict reliability requirements. Testing frameworks such as NUnit make C# amenable to test-driven development and thus a good language for use with Extreme Programming (XP). Its strong typing helps to prevent many programming errors that are common in weakly typed languages.
- A description of the C# language and introduction to this Wikibook.
- Getting started with C#
- A simple C# program and where to get tools to compile it.
- Basic syntax
- Describes the basics in how the applications you write will be interpreted.
- Naming conventions
- Quickly describes the generally accepted naming conventions for C#.
- The entities used to store data of various shapes.
- Summarizes the operators, such as the '+' in addition, available in C#.
- Data structures
- Enumerations, structs, and more.
- Control statements
- Loops, conditions, and more. How the program flow is controlled.
- Responding to errors that can occur.
- Giving your code its own space to live in.
- The blueprints of objects that describes how they should work.
- Cornerstones of any object-oriented programming language, objects are the tools you use to perform work.
- Encapsulation and accessor levels
- Explains protection of object states by encapsulation, or the bundling of an object's data and functionality.
- Re-using existing code to improve or specialize the functionality of an object.
- Define a template, on which to base sub-classes.
- Delegates and Events
- Learn about delegates, anonymous delegates, lambda expressions, and events.
- Abstract classes
- Build partially implemented classes.
- Partial classes
- Split a class over several files to allow multiple users to develop, but also to stop code generators interfering with source code.
- Allow commonly used collections and classes to appear to have specialization for your custom class.
- Extension methods
- Extend the functionality of existing types.
- Object Lifetime
- Learn about the lifetime of objects, where they are allocated and learn about garbage collection.
- Design Patterns
- Learn commonly used design methodologies to simplify and/or improve your development framework.
The .NET Framework
- .NET Framework Overview
- An overview of the .NET class library used in C#.
- Console Programming
- Input and Output using the console.
- Windows Forms
- GUI Programming with Windows Forms.
- Effectively manage (add, remove, find, iterate, etc.) large sets of data.
- Learn how to run code concurrently and how to synchronize code.
- Communicating with unmanaged code
|Special C# Identifiers|
- Excellent and Illustrative C# Programming Tutorials From Novice to Professional by the team of Computer Systems Engineers with approach-based clarity for those who don't even know how to program , but want to program
- Free C# Programming Resources
- C# Tutorial
- An Introduction to Mono Development by Andrew Troelsen
- C# Environment setup Visual C# environment setup details from MSDN
- C# FAQ C# FAQ, Blogs and Forums.
- C# Language Specification download page at ECMA
- C# Programming Tutorial
- C# Programming Tutorial Collection
- C# Yellow Book (via pdf download)
- Microsoft Visual C# Express Edition : A free development environment created by Microsoft for writing C# Applications.
- : The C++ Programming Language read guide to C++
- Mono Project : C# Development Environment for Linux, Windows, and other platforms.
- C# 1 Introduction to programming and the C# language : C# 1 Introduction to programming and the C# language.
- C# information | <urn:uuid:04f36e9f-8b37-4f50-8d96-c6689a791442> | 3.296875 | 1,096 | Knowledge Article | Software Dev. | 31.498375 | 95,637,883 |
Decades after one of humankind's greatest achievements of getting a man on the Moon, trips there remain surprisingly rare. Former astronaut Chris Hadfield and others explain why.
A seemingly regular asteroid turns out to be double trouble as scientists found it is actually a binary system of two objects orbiting each other. This is only the fourth equal mass binary system ever recorded.
It's the end of an era. For decades, the Cape Canaveral launch towers have stood as stalwarts symbolizing the United States space program. Now, the landmark gets demolished just as Delta nears its end.
Life on Mars? Not exactly, but the seasonal spiders that appear on Mars' surface has an interesting story behind them, especially since it's a natural process that doesn't occur on Earth.
NASA is looking for creative ways to deal with the trash accummulated in space. As humanity travels further into the cosmos, the prospect of garbage management becomes trickier and much more important.
NASA may have collected evidence of organic Martian matter 40 years ago — then burned it away accidentally in the Viking landers. A new study tackles the decades-old mystery.
The Kepler Space Telescope has almost run its course. The famous planet hunter is running low on fuel and is now placed on hibernation mode in anticipation of its last data dump.
Astro-mice are on a rocket to the International Space Station as part of a project that's studying the effects of zero-gravity on sleeping patterns and the gut. Ten rodents will be staying for a record-breaking 90 days on the station.
Skywatching enthusiasts find a new favorite spot at the John Glenn Astronomy Park, which Ohio named after an iconic astronaut, the late John Glenn. The park features 12 powerful telescopes and perfect conditions for stargazing.
Once again, NASA delays the launch of cutting-edge James Webb Space Telescope following the recommendations of an independent review board that called out technical issues and human error in the observatory's development.
Aliens might be out there, and if they are, NASA wants to find them. The NExSS project releases a series of papers to help scientists who are hunting for extraterrestrial life in far-flung planets.
It almost looks like a post-Impressionist painting, but this image is actually a photo of Jupiter. As it makes its 13th close flyby of the gas giant, Juno captures the swirling clouds of the planet rippling over the surface.
The Martian dust storm continues to rage, now swallowing up the entire planet and keeping the Opportunity rover silent and out of reach. Unfortunately, this gigantic storm shows no signs of stopping soon.
Laura Cicco goes up against NASA, filing a case against the space agency to keep it away from the moon dust given to her by Neil Armstrong. The iconic astronaut was allegedly friends with Cicco's late father. | <urn:uuid:9f4a2bfb-7f4b-4f59-b968-fb350be1bc8a> | 2.859375 | 580 | Content Listing | Science & Tech. | 46.309008 | 95,637,888 |
Category: Built-In Types
3x3 matrix datatype.
|Basis||Basis ( Quat from )|
|Basis||Basis ( Vector3 from )|
|Basis||Basis ( Vector3 axis, float phi )|
|Basis||Basis ( Vector3 x_axis, Vector3 y_axis, Vector3 z_axis )|
|float||determinant ( )|
|Vector3||get_euler ( )|
|int||get_orthogonal_index ( )|
|Vector3||get_scale ( )|
|Basis||inverse ( )|
|Basis||orthonormalized ( )|
|Basis||rotated ( Vector3 axis, float phi )|
|Basis||scaled ( Vector3 scale )|
|Basis||slerp ( Basis b, float t )|
|float||tdotx ( Vector3 with )|
|float||tdoty ( Vector3 with )|
|float||tdotz ( Vector3 with )|
|Basis||transposed ( )|
|Vector3||xform ( Vector3 v )|
|Vector3||xform_inv ( Vector3 v )|
3x3 matrix used for 3D rotation and scale. Contains 3 vector fields x,y and z as its columns, which can be interpreted as the local basis vectors of a transformation. Can also be accessed as array of 3D vectors. These vectors are orthogonal to each other, but are not necessarily normalized (due to scaling). Almost always used as orthogonal basis for a Transform.
For such use, it is composed of a scaling and a rotation matrix, in that order (M = R.S).
Member Function Description¶
Create a rotation matrix from the given quaternion.
Create a rotation matrix (in the YXZ convention: first Z, then X, and Y last) from the specified Euler angles, given in the vector format as (X-angle, Y-angle, Z-angle).
Create a rotation matrix which rotates around the given axis by the specified angle, in radians. The axis must be a normalized vector.
Create a matrix from 3 axis vectors.
- float determinant ( )
Return the determinant of the matrix.
- Vector3 get_euler ( )
Assuming that the matrix is a proper rotation matrix (orthonormal matrix with determinant +1), return Euler angles (in the YXZ convention: first Z, then X, and Y last). Returned vector contains the rotation angles in the format (X-angle, Y-angle, Z-angle).
- int get_orthogonal_index ( )
This function considers a discretization of rotations into 24 points on unit sphere, lying along the vectors (x,y,z) with each component being either -1,0 or 1, and returns the index of the point best representing the orientation of the object. It is mainly used by the grid map editor. For further details, refer to Godot source code.
- Vector3 get_scale ( )
Assuming that the matrix is the combination of a rotation and scaling, return the absolute value of scaling factors along each axis.
- Basis inverse ( )
Return the inverse of the matrix.
- Basis orthonormalized ( )
Return the orthonormalized version of the matrix (useful to call from time to time to avoid rounding error for orthogonal matrices). This performs a Gram-Schmidt orthonormalization on the basis of the matrix.
Introduce an additional rotation around the given axis by phi (radians). The axis must be a normalized vector.
Introduce an additional scaling specified by the given 3D scaling factor.
Assuming that the matrix is a proper rotation matrix, slerp performs a spherical-linear interpolation with another rotation matrix.
Transposed dot product with the x axis of the matrix.
Transposed dot product with the y axis of the matrix.
Transposed dot product with the z axis of the matrix.
- Basis transposed ( )
Return the transposed version of the matrix.
Return a vector transformed (multiplied) by the matrix.
Return a vector transformed (multiplied) by the transposed matrix. Note that this results in a multiplication by the inverse of the matrix only if it represents a rotation-reflection. | <urn:uuid:04cfb9ff-216a-4a93-acb6-8f0c4cd6526c> | 2.640625 | 953 | Documentation | Software Dev. | 44.628367 | 95,637,893 |
Species Detail - Lake Orb Mussel (Musculium lacustre) - Species information displayed is based on the dataset "All Ireland Non-Marine Molluscan Database".
Terrestrial Map - 10kmDistribution of the number of records recorded within each 10km grid square (ITM).
Marine Map - 50kmDistribution of the number of records recorded within each 50km grid square (WGS84).
Lake Orb Mussel
Threatened Species: Vulnerable
(O. F. Müller, 1774)
25 January (recorded in 1975)
30 October (recorded in 1973)
Conchological Society of Great Britain and Ireland, All Ireland Non-Marine Molluscan Database, National Biodiversity Data Centre, Ireland, Lake Orb Mussel (Musculium lacustre), accessed 16 July 2018, <https://maps.biodiversityireland.ie/Dataset/1/Species/123913> | <urn:uuid:0044358e-db84-49dd-91b3-5f392829b8af> | 2.609375 | 205 | Structured Data | Science & Tech. | 31.044245 | 95,637,896 |
Seeing Sextuple! These six infrared images of Saturn's moon Titan, as compared with the center image of Titan as it appears in natural light, represent some of the clearest, most seamless-looking global views of the icy moon's surface produced so far. The views were created using 13 years of data acquired by an instrument on board our Cassini spacecraft. The images are the result of a focused effort to smoothly combine data from different observations made under various lighting and viewing conditions.
Observing the surface of Titan is difficult because of the haze surrounding it and small particles called aerosols in the upper atmosphere that scatter visible light. While this is the case, Titan’s surface can be more readily observed in a few infrared "windows" - infrared wavelengths where scattering and absorption of light is much weaker. This is where our instrument excelled, parting the haze to obtain these clear images of Titan’s surface.
This unique set of images shows Titan’s complex surface, sporting myriad geologic features and compositional units. Our technology has paved the way for future infrared instruments that could observe Titan at much higher resolutions, revealing features that were not detectable by any of Cassini’s instruments.
Credit: NASA/JPL-Caltech/Stéphane Le Mouélic, University of Nantes, Virginia Pasek, University of Arizona
#nasa #space #saturn #solarsystem #infrared #spacecraft #titan #science | <urn:uuid:28688b21-4f3f-47ec-ac78-ee462c73b8de> | 3.125 | 302 | Personal Blog | Science & Tech. | 22.682193 | 95,637,942 |
Unexpected and stunning new physical phenomena result when light interacts with a shock wave or shocklike dielectric modulation propagating through a photonic crystal. These new phenomena include the capture of light at the shock wave front and reemission at a tunable pulse rate and carrier frequency across the band gap, and bandwidth narrowing as opposed to the ubiquitous bandwidth broadening. To our knowledge, these effects do not occur in any other physical system and are all realizable under experimentally accessible conditions. Furthermore, their generality make them amenable to observation in a variety of time-dependent photonic crystal systems, which has significant technological implications.
Mendeley saves you time finding and organizing research
Choose a citation style from the tabs below | <urn:uuid:912f0922-0996-4919-a54e-2a452421e56c> | 2.53125 | 147 | Academic Writing | Science & Tech. | 1.040431 | 95,637,946 |
Common name: northern river crangonyctid [English]
available through www.itis.gov
Native Range: It is widely distributed in east-central United States and southern Canada, occurring largely west of the Appalachians, extending approximately from the Great Lakes region, south and southwest to Louisiana and Texas (Zhang and Holsinger, 2003 cited in Encyclopedia of Life).
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 Crangonyx pseudogracilis are found here.
Table last updated 5/25/2018
† Populations may not be currently present.
References: (click for full references)
Revision Date: 8/26/2015
Encyclopedia of Life (http://eol.org/pages/344045/details)
U.S. Geological Survey, 2018, Crangonyx pseudogracilis Bousfield, 1958: U.S. Geological Survey, Nonindigenous Aquatic Species Database, Gainesville, FL, https://nas.er.usgs.gov/queries/FactSheet.aspx?SpeciesID=2387, Revision Date: 8/26/2015, Access Date: 7/21/2018
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:f41b8412-8a65-4d53-b0c2-c9c0c303c207> | 3 | 389 | Knowledge Article | Science & Tech. | 42.677245 | 95,637,979 |
Filters: Tags: brown bear (X)50 results (39ms)
Estimating population size of grizzly bears using hair capture, DNA profiling, and mark-recapture analysis
Changes in the structure of an increasing brown bear population with distance from core areas: another example of presaturation female dispersal?
Abundance of brown bears and wolves in central south Norway after 1733 as revealed by bounty records
Grizzly Bear, Ursus arctos, Usurps Bison Calf, Bison bison, Captured by Wolves, Canis lupus, in Yellowstone National Park, Wyoming
Minimum viable population and reserve sizes for naturally regulated grizzly bears in British Columbia
Conservation Endocrinology: a Noninvasive Tool to Understand Relationships between Carnivore Colonization and Ecological Carrying Capacity
DNA-based population estimate for grizzly bears Ursus arctos in northeastern British Columbia, Canada
Assessing the risk of extinction for the brown bear (Ursus arctos) in the Cordillera Cantabrica, Spain
Estimating effects of adult male mortality on grizzly bear population growth and persistence using matrix models
Moose, Caribou, and Grizzly Bear Distribution in Relation to Road Traffic in Denali National Park, Alaska
Mammalian predator-prey imbalance: Grizzly bear and wolf extinction affect avian neotropical migrants
Subsistence Land Mammal Harvests and Uses, Yukon Flats, Alaska: 2008-2010 Harvest Report and Ethnographic Update
This report presents the results of a harvest survey and ethnographic research project that investigated the subsistence uses of large land mammals and furbearers in Game Management Unit 25 in the Yukon Flats region of Interior Alaska. Large land mammal species harvested and used by Yukon Flats residents include moose Alces alces, caribou Rangifer tarandus, black bear Ursus americanus, and brown bear Ursus arctos. Furbearing species included in this study are marten Martes americana, lynx Lynx canadensis, and wolf Canis lupus. For the 2008–2009 study year a total of 284 of 467 households (approximately 61%) were surveyed in the 7 Yukon Flats communities of Beaver, Birch Creek, Chalkyitsik, Circle, Fort Yukon, Stevens... | <urn:uuid:eb97c427-3be4-412c-87d9-56192ab6cf66> | 2.609375 | 491 | Content Listing | Science & Tech. | -6.398562 | 95,637,986 |
NASA's Interstellar Boundary Explorer (IBEX) spacecraft has made the first observations of very fast hydrogen atoms coming from the moon, following decades of speculation and searching for their existence.
During spacecraft commissioning, the IBEX team turned on the IBEX-Hi instrument, built primarily by Southwest Research Institute (SwRI) and the Los Alamos National Laboratory, which measures atoms with speeds from about half a million to 2.5 million miles per hour. Its companion sensor, IBEX-Lo, built by Lockheed Martin, the University of New Hampshire, NASA Goddard Space Flight Center, and the University of Bern in Switzerland, measures atoms with speeds from about one hundred thousand to 1.5 million mph.
"Just after we got IBEX-Hi turned on, the moon happened to pass right through its field of view, and there they were," says Dr. David J. McComas, IBEX principal investigator and assistant vice president of the SwRI Space Science and Engineering Division. "The instrument lit up with a clear signal of the neutral atoms being detected as they backscattered from the moon."
The solar wind, the supersonic stream of charged particles that flows out from the sun, moves out into space in every direction at speeds of about a million mph. The Earth's strong magnetic field shields our planet from the solar wind. The moon, with its relatively weak magnetic field, has no such protection, causing the solar wind to slam onto the moon's sunward side.
From its vantage point in space, IBEX sees about half of the moon -- one quarter of it is dark and faces the nightside (away from the sun), while the other quarter faces the dayside (toward the sun). Solar wind particles impact only the dayside, where most of them are embedded in the lunar surface, while some scatter off in different directions. The scattered ones mostly become neutral atoms in this reflection process by picking up electrons from the lunar surface.
The IBEX team estimates that only about 10 percent of the solar wind ions reflect off the sunward side of the moon as neutral atoms, while the remaining 90 percent are embedded in the lunar surface. Characteristics of the lunar surface, such as dust, craters and rocks, play a role in determining the percentage of particles that become embedded and the percentage of neutral particles, as well as their direction of travel, that scatter.
McComas says the results also shed light on the "recycling" process undertaken by particles throughout the solar system and beyond. The solar wind and other charged particles impact dust and larger objects as they travel through space, where they backscatter and are reprocessed as neutral atoms. These atoms can travel long distances before they are stripped of their electrons and become ions and the complicated process begins again.
The combined scattering and neutralization processes now observed at the moon have implications for interactions with objects across the solar system, such as asteroids, Kuiper Belt objects and other moons. The plasma-surface interactions occurring within protostellar nebula, the region of space that forms around planets and stars -- as well as exoplanets, planets around other stars -- also can be inferred.
IBEX's primary mission is to observe and map the complex interactions occurring at the edge of the solar system, where the million miles per hour solar wind runs into the interstellar material from the rest of the galaxy. The spacecraft carries the most sensitive neutral atom detectors ever flown in space, enabling researchers to not only measure particle energy, but also to make precise images of where they are coming from.
Around the end of the summer, the team will release the spacecraft's first all-sky map showing the energetic processes occurring at the edge of the solar system. The team will not comment until the image is complete, but McComas hints, "It doesn't look like any of the models."
IBEX is the latest in NASA's series of low-cost, rapidly developed Small Explorers spacecraft. The IBEX mission was developed by SwRI with a national and international team of partners. NASA's Goddard Space Flight Center manages the Explorers Program for NASA's Science Mission Directorate.
"Lunar Backscatter and Neutralization of the Solar Wind: First Observations of Neutral Atoms from the Moon," by McComas, F. Allegrini, P. Bochsler, P. Frisch, H.O. Funsten, M. Gruntman, P.H. Janzen, H. Kucharek, E. Moebius, D.B. Reisenfeld, and N.A. Schwadron, was just published by Geophysical Research Letters, doi:10.1029/2009GL038794.
Maria Martinez | EurekAlert!
Global study of world's beaches shows threat to protected areas
19.07.2018 | NASA/Goddard Space Flight Center
NSF-supported researchers to present new results on hurricanes and other extreme events
19.07.2018 | National Science Foundation
A new manufacturing technique uses a process similar to newspaper printing to form smoother and more flexible metals for making ultrafast electronic devices.
The low-cost process, developed by Purdue University researchers, combines tools already used in industry for manufacturing metals on a large scale, but uses...
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
20.07.2018 | Power and Electrical Engineering
20.07.2018 | Information Technology
20.07.2018 | Materials Sciences | <urn:uuid:52858c5c-f1ba-427c-8d8b-bafc264d4be2> | 3.875 | 1,541 | Content Listing | Science & Tech. | 44.791486 | 95,637,998 |
"We won't be able to send a space probe to Comet Lulin, but Swift is giving us some of the information we would get from just such a mission," said Jenny Carter, at the University of Leicester, U.K., who is leading the study.
"The comet is releasing a great amount of gas, which makes it an ideal target for X-ray observations," said Andrew Read, also at Leicester.
A comet is a clump of frozen gases mixed with dust. These "dirty snowballs" cast off gas and dust whenever they venture near the sun. Comet Lulin, which is formally known as C/2007 N3, was discovered last year by astronomers at Taiwan's Lulin Observatory. The comet is now faintly visible from a dark site. Lulin will pass closest to Earth -- 38 million miles, or about 160 times farther than the moon -- late on the evening of Feb. 23 for North America.
On Jan. 28, Swift trained its Ultraviolet/Optical Telescope (UVOT) and X-Ray Telescope (XRT) on Comet Lulin. "The comet is quite active," said team member Dennis Bodewits, a NASA Postdoctoral Fellow at the Goddard Space Flight Center in Greenbelt, Md. "The UVOT data show that Lulin was shedding nearly 800 gallons of water each second." That's enough to fill an Olympic-size swimming pool in less than 15 minutes.
Swift can't see water directly. But ultraviolet light from the sun quickly breaks apart water molecules into hydrogen atoms and hydroxyl (OH) molecules. Swift's UVOT detects the hydroxyl molecules, and its images of Lulin reveal a hydroxyl cloud spanning nearly 250,000 miles, or slightly greater than the distance between Earth and the moon.Comet Lulin was passing through the constellation Libra when Swift imaged it. This view merges the Swift data with a Digital Sky Survey image of the star field. Credit: NASA/Swift/Univ. of Leicester/DSS (STScI, AURUA)/Bodewits et al.
> Larger image The UVOT includes a prism-like device called a grism, which separates incoming light by wavelength. The grism's range includes wavelengths in which the hydroxyl molecule is most active. "This gives us a unique view into the types and quantities of gas a comet produces, which gives us clues about the origin of comets and the solar system," Bodewits explains. Swift is currently the only space observatory covering this wavelength range.
In the Swift images, the comet's tail extends off to the right. Solar radiation pushes icy grains away from the comet. As the grains gradually evaporate, they create a thin hydroxyl tail.
Farther from the comet, even the hydroxyl molecule succumbs to solar ultraviolet radiation. It breaks into its constituent oxygen and hydrogen atoms. "The solar wind -- a fast-moving stream of particles from the sun -- interacts with the comet's broader cloud of atoms. This causes the solar wind to light up with X rays, and that's what Swift's XRT sees," said Stefan Immler, also at Goddard.
This interaction, called charge exchange, results in X-rays from most comets when they pass within about three times Earth's distance from the sun. Because Lulin is so active, its atomic cloud is especially dense. As a result, the X-ray-emitting region extends far sunward of the comet.
"We are looking forward to future observations of Comet Lulin, when we hope to get better X-ray data to help us determine its makeup," noted Carter. "They will allow us to build up a more complete 3-D picture of the comet during its flight through the solar system."
Other members of the team include Michael Mumma and Geronimo Villanueva at Goddard.
NASA's Goddard Space Flight Center in Greenbelt, Md., manages the Swift satellite. It is being operated in collaboration with partners in the U.S., the United Kingdom, Italy, Germany and Japan. NASA's Fermi Gamma-ray Space Telescope is an astrophysics and particle physics observatory developed in collaboration with the U.S. Department of Energy and with important contributions from academic institutions and partners in France, Germany, Italy, Japan, Sweden, and the U.S.
Francis Reddy | EurekAlert!
Further reports about: > COMET > Comet Lulin > Earth's magnetic field > Gamma-ray > Greenbelt > NASA's Swift Gamma-ray Explorer satellite > Space > Telescope > UVOT > Ultraviolet/Optical Telescope > X-ray images > X-ray microscopy > X-ray observations > XRT > cosmic explosions > high-energy outbursts > hydrogen atom > hydrogen atoms > hydroxyl (OH) molecules > hydroxyl molecules > solar radiation > solar system > solar wind
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:8d77a033-e499-4982-bb25-c6c74bb6ebb5> | 3.53125 | 1,590 | Content Listing | Science & Tech. | 46.955618 | 95,637,999 |
Subtropical Storm Beryl Moving Slowing in Atlantic
At a Glance
- In the eastern Pacific, Hilary and Irwin performed their daisy-wheel dance called the Fujiwhara effect.
- Hilary and Irwin didn't threaten land directly, but generated high surf for Southern California.
- This Fujiwhara effect also happened thousands of miles away in the western Pacific east of Japan just days prior.
- To see this happen more than once a year is meteorologically impressive.
A pair of Pacific tropical storms participated in a bizarre, circular dance known as the Fujiwhara effect, generating high surf along the Southern California coast just days after a similar interaction involving separate tropical cyclones in the western Pacific Ocean.
(MORE: Hurricane Central)
Their centers became sufficiently close – just over 400 miles apart – that a phenomenon meteorologists call the Fujiwhara effect kicked in.
Named after a Japanese researcher who discovered this in experiments with water in the early 1920s, the Fujiwhara effect details how two tropical cyclones less than 900 miles apart rotate counter-clockwise about one another.
Think of the teacup ride at Disney or the Tilt-a-Whirl at your local county fair, but with tropical systems instead. In the teacup ride, adjacent teacups can not only spin, but revolve about each other.
In this case, Irwin, the southern storm of the pair, after being stalled for a day or two, got pulled north and revolved counter-clockwise around the weakening circulation of Hilary.
Each storm rotated about each other, before merging and weakening over cooler water in a more stable air mass.
(If you're interested in a more technical explanation, University of Albany, SUNY Ph.D. candidate Philippe Papin tweeted an excellent explanation.)
While neither named storm impacted land directly, there was one impact. Higher swells were forecast to reach the Southern California coast.
Separate West Pacific Dance
More than 5,000 miles away, Typhoon Noru, the first typhoon of 2017, teamed up with another tropical cyclone named Kulap in a separate Fujiwhara effect.
While Kulap had degenerated to a remnant, one could still pick out its leftover circulation in Himawari-8 visible satellite imagery July 27 south-southwest of Noru.
July 25, thanks in part to the Fujiwhara interaction, Noru crossed its path from the previous week completing an oval-shaped loop.
To see this happen once a season isn't unusual, according to a 2014 study in the western Pacific Ocean, but for this to happen in two separate areas within days is very unusual.
Jonathan Erdman is a senior meteorologist at weather.com and has been an incurable weather geek since a tornado narrowly missed his childhood home in Wisconsin at age 7. Follow him on Facebook and Twitter.
MORE ON WEATHER.COM: Atlantic Basin Retired Hurricanes and Tropical Storm Names | <urn:uuid:e56cf286-8e21-4783-8f55-a421a1aaafbf> | 3.34375 | 610 | News Article | Science & Tech. | 32.342138 | 95,638,013 |
Chlorocypha ghesquierei Fraser, 1959
Congo Red Jewel
Type locality: Eala, DRC
No full diagnosis of this species, known only with certainty from the type locality, is presently available. However, the male differs subtly from similar species with (a) an all-red abdominal dorsum; and (b) all black legs; by being (1) fairly small, Hw 21.0-22.0 mm rather than 22.0-25.0 mm; having (2) a dark face with prominent double pale (probably yellow or blue in life) spots on the labrum and pale genae extending as narrow wedges along the eyes; (3) a dark thorax with the pale ante-humeral stripes obscured with age, leaving only two yellowish bands on the sides; and (4) a quite extensively black dorsum of S2 contrasting with the almost unmarked remaining abdomen. [Adapted from Dijkstra, Kipping & Mézière 2015]
Not known, but probably rivers or streams shaded by or in open areas in forest. Probably often with submerged roots, dead trunks or branches and/or coarse detritus. From 300 to 900 m above sea level.
Map citation: Clausnitzer, V., K.-D.B. Dijkstra, R. Koch, J.-P. Boudot, W.R.T. Darwall, J. Kipping, B. Samraoui, M.J. Samways, J.P. Simaika & F. Suhling, 2012. Focus on African Freshwaters: hotspots of dragonfly diversity and conservation concern. Frontiers in Ecology and the Environment 10: 129-134.
- Fraser, F.C. (1959). A new species of Chlorocypha and some notes on the synonymy of other species of Odonata from the Belgian Congo. Revue Zoologie Botanique Africaines, 60, 307-312. [PDF file]
- Pinhey, E.C.G. (1967). African Chlorocyphidae (Odonata). Journal Entomological Society Southern Africa, 29, 161-197. [PDF file]
Citation: Dijkstra, K.-D.B (editor). African Dragonflies and Damselflies Online. http://addo.adu.org.za/ [2018-07-17]. | <urn:uuid:a456376a-afd0-4155-99cf-40edc6bbc4f1> | 2.875 | 508 | Knowledge Article | Science & Tech. | 73.718125 | 95,638,022 |
Analysis of the new Hubble data shows that the nucleus has a diameter of approximately 0.93 miles (1.5 kilometers), which is consistent with previous estimates.
The comet is in a highly active state as it approaches the Sun. The Hubble data show that the coma is remarkably uniform, with no evidence for the types of outgassing jets seen from most "Jupiter Family" comets, of which Hartley 2 is a member.
Jets can be produced when the dust emanates from a few specific icy regions, while most of the surface is covered with relatively inert, meteoritic-like material. In stark contrast, the activity from Hartley 2's nucleus appears to be more uniformly distributed over its entire surface, perhaps indicating a relatively "young" surface that hasn't yet been crusted over.
information about the comet's chemical composition that might not be obtainable any other way, including measurements by DIXI. The Hubble team is specifically searching for emissions from carbon monoxide (CO) and diatomic sulfur (S2). These molecules have been seen in other comets but have not yet been detected in 103P/Hartley 2.
103P/Hartley has an orbital period of 6.46 years. It was discovered by Malcolm Hartley in 1986 at the Schmidt Telescope Unit in Siding Spring, Australia. The comet will pass within 11 million miles of Earth (about 45 times the distance to the Moon) on October 20. During that time the comet may be visible to the naked eye as a 5th magnitude "fuzzy star" in the constellation Auriga.
Credit: NASA, ESA, and H. Weaver (The Johns Hopkins University Applied Physics Lab)For images and more information about comet Hartley 2, visit:
Ray Villard | Newswise Science News
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:c442aa83-6e27-4f97-8412-45cec63d2f2a> | 3.171875 | 1,010 | Content Listing | Science & Tech. | 41.720881 | 95,638,024 |
However, no one had been able to find a distinct gait change – such as a change in stride length or frequency – associated with the latter stages of pregnancy.
Intrigued by the ways that newborn dolphins learn to swim after birth, Shawn Noren from the Institute of Marine Science, University of California Santa Cruz, realised that she had the perfect opportunity to find out how pregnancy affects female dolphins.
Joining a pod of dolphins at Dolphin Quest, Hawaii, just before two of the females gave birth, Noren analysed the impact of pregnancy on the animals' streamlined shape and mobility. She publishes her discovery that pregnant dolphins are significantly disadvantaged by their burden and adopt a new swimming style (gait) in The Journal of Experimental Biology at http://jeb.biologists.org.
'The pregnant females had huge protrusions where the fetus was sitting towards the back end of the body', says Noren, who donned SCUBA gear and spent a large portion of the final fortnight of the dolphins' pregnancies filming under water as they swam parallel to her camera between their trainers. Noren also filmed the dolphin mothers immediately after their calves were born and at regular intervals until the calves were 2 years old. Comparing the footage before and after delivery, Noren realised that pregnant females were slower. Their top speed was restricted to 3.54 m s, whereas they were able to swim at much higher speeds after giving birth. 'Two to three metres per second is a comfortable speed for most bottlenose dolphins,' says Noren, 'but these pregnant animals did not feel comfortable going beyond that.'
She also measured the animals' girth and calculated their frontal surface area, and realised that the pregnancy had a colossal impact, increasing their frontal surface area by an enormous 51%. And when Noren measured the drag experienced by the animals as they glided through the water, she discovered that it doubled when the mothers were close to delivery.
The pregnant dolphins also had another problem: their increased fat stores in preparation for lactation had also increased their buoyancy. 'The buoyancy issue is going to be problematic when you are going down on a dive to capture prey and they are going to need extra energy to overcome that buoyant force', says Noren. So, pregnancy had a dramatic effect on the dolphin's hydrodynamics, but had it changed their swimming style? Did the pregnant dolphins move with a different gait?
Manually digitising the position of the animals' flukes (tail fins) as they beat up and down, Noren discovered that the pregnant females were unable to sweep their flukes as far as they could after birth. They had reduced the amplitude of their tail beat by 13% and they compensated for the reduced propulsion by beating their flukes faster. The pregnant dolphins had changed gait.
Having found how pregnancy affects soon-to-be dolphin mothers, Noren outlines the additional risks that the females face. Unable to outrun predators, heavily pregnant dolphins are more vulnerable to attack and they may not be able to keep up with the pod if pursued by fishing vessels. Explaining that tuna are still fished using massive nets in the eastern tropical Pacific, Noren says, 'Here is a fast speed event, so it is possible the near term pregnant females are being left behind in the chase. They are reliant on a large pod for protection and cooperative feeding and once the animal is separated it would be hard for it to find the pod again.'
IF REPORTING ON THIS STORY, PLEASE MENTION THE JOURNAL OF EXPERIMENTAL BIOLOGY AS THE SOURCE AND, IF REPORTING ONLINE, PLEASE CARRY A LINK TO: http://jeb.biologists.org
REFERENCE: Noren, S. R., Redfern, J. V. and Edwards, E. F. (2011). Pregnancy is a drag: hydrodynamics, kinematics and performance in pre- and post-parturition bottlenose dolphins (Tursiops truncatus). J. Exp. Biol. 214, 4149-4157.
This article is posted on this site to give advance access to other authorised media who may wish to report on this story. Full attribution is required, and if reporting online a link to jeb.biologists.com is also required. The story posted here is COPYRIGHTED. Therefore advance permission is required before any and every reproduction of each article in full. PLEASE CONTACT email@example.com
World’s Largest Study on Allergic Rhinitis Reveals new Risk Genes
17.07.2018 | Helmholtz Zentrum München - Deutsches Forschungszentrum für Gesundheit und Umwelt
Plant mothers talk to their embryos via the hormone auxin
17.07.2018 | Institute of Science and Technology Austria
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
17.07.2018 | Information Technology
17.07.2018 | Materials Sciences
17.07.2018 | Power and Electrical Engineering | <urn:uuid:e663d350-3c7b-4ab0-89ac-c83b90170c43> | 3.5 | 1,585 | Content Listing | Science & Tech. | 45.102582 | 95,638,035 |
Alan Werner, professor of geology at Mount Holyoke College, said that decreasing amounts of Arctic snow and ice in summer will lead to a greater degree of heat absorption at the North Pole.
The reason, Werner said, is because the loss of snow and ice makes the earth’s surface less reflective, meaning solar radiation—or heat—is absorbed in greater amounts by the exposed dark ocean or tundra.
“That’s the thing that’s happening very abruptly, or at least in geologic time scales, very quickly,” Werner said. “That the high latitudes are warming at a much faster rate than the other latitudes.”
Werner’s observation follows the announcement in September by the National Snow and Ice Data Center that the surface area of Arctic sea ice had reached a new low in 2012, breaking a previous record reached in 2007.
What the new data suggests, Werner said, is that the Arctic Ocean will likely be free of sea ice during summer in the next few decades, which may trigger significant changes in climate across the globe.
“One thing about humans living on the planet is that we don’t do well with change,” Werner said. “The changes that we’re talking about are changes that are going to be difficult for humans to adapt to.”
Mount Holyoke College is able to support broadcast quality interviews via its dedicated ISDN line and recording studio. For more information, contact John Martins, MHC Multimedia News Manager, at 413-538-2603 or firstname.lastname@example.org.Alan Werner, Professor of Geology
Alan Werner | Newswise
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
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:986d0103-5d58-4369-bd6b-73332c8d6747> | 3.6875 | 984 | Content Listing | Science & Tech. | 45.086652 | 95,638,063 |
African Register of Marine Species (AfReMaS)
#accepted species: 24,027
The African Register of Marine Species is a taxonomic database of marine species found along the African coasts. The database was originally developed as the Marine Species Database for Eastern Africa (MASDEA). It was extended thereafter to include species from the entire African coast.
The African Register of Marine Species aims to compile and manage an authoritative list of species occurring along the African marine coasts. It is intended to be used as support for biodiversity research for conservation and sustainable management of marine environment.
The list currently includes species belonging mostly to mollusks, sponges and decapods which had been updated from data mining workshops conducted by ODINAFRICA. Currently the focus is on addition of other taxonomic groups such as fish, phytoplankton and zooplankton.
Content from AfReMaS is shared with the World Register of Marine Species (WoRMS). The objective of WoRMS is to provide an authoritative and comprehensive list of names of marine organisms, including information on synonyms.
The AfReMaS Editorial Board consists of taxonomic and data management experts. Itis in process to be extended to internationally recognize taxonomic editors. The AfReMaS editorial board does not directly have the authority to modify taxonomic information stored in the register; however, the editors may collaborate with WoRMS taxonomic editors to effect changes
The editorial board is mainly tasked to:
- Contribute to the data mining, identification of datasets and identification of authoritative literature associated with taxa distribution
- Assist with the review of existing unverified register records
- Assist with the compilation of distribution records for areas of interest to African scientists
Odido, M.; Appeltans, W.; BelHassen, M.; Mussai, P.; Nsiangango, S.E.; Vandepitte, L.; Wambiji, N.; Zamouri, N. Jiddou, A.M. (Eds) (2018). African Register of Marine Species. Accessed at http://www.marinespecies.org/afremas on 2018-07-21
Like all such lists, AfReMaS undoubtedly contains errors, as it is an evolving process, new species are added, some are shown to be invalid (or misidentified), and some species are recognized as synonymous with other names. The AfReMaS editorial board, in collaboration with WoRMS taxonomic editors, maintains these registers but is aware that they may not be complete and may contain errors. The board cannot be held responsible for any errors or misuse of data contained in this register. Comments from our users are more than welcome, so if you come across incorrect or incomplete information, or you are willing to contribute to this initiative, please contact email@example.com. | <urn:uuid:e1c532da-01f2-46bf-97fe-b4281cf2d29e> | 2.984375 | 591 | Knowledge Article | Science & Tech. | 21.804687 | 95,638,072 |
|Using the GNU Compiler Collection (GCC)|
Often large projects have many header files that are included in every source file. The time the compiler takes to process these header files over and over again can account for nearly all of the time required to build the project. To make builds faster, GCC allows users to `precompile' a header file; then, if builds can use the precompiled header file they will be much faster.
To create a precompiled header file, simply compile it as you would any other file, if necessary using the -x option to make the driver treat it as a C or C++ header file. You will probably want to use a tool like make to keep the precompiled header up-to-date when the headers it contains change.
A precompiled header file will be searched for when
seen in the compilation. As it searches for the included file
(see Search Path) the
compiler looks for a precompiled header in each directory just before it
looks for the include file in that directory. The name searched for is
the name specified in the
#include with ‘.gch’ appended. If
the precompiled header file can't be used, it is ignored.
For instance, if you have
#include "all.h", and you have
all.h.gch in the same directory as all.h, then the
precompiled header file will be used if possible, and the original
header will be used otherwise.
Alternatively, you might decide to put the precompiled header file in a
directory and use -I to ensure that directory is searched
before (or instead of) the directory containing the original header.
Then, if you want to check that the precompiled header file is always
used, you can put a file of the same name as the original header in this
directory containing an
This also works with -include. So yet another way to use precompiled headers, good for projects not designed with precompiled header files in mind, is to simply take most of the header files used by a project, include them from another header file, precompile that header file, and -include the precompiled header. If the header files have guards against multiple inclusion, they will be skipped because they've already been included (in the precompiled header).
If you need to precompile the same header file for different languages, targets, or compiler options, you can instead make a directory named like all.h.gch, and put each precompiled header in the directory, perhaps using -o. It doesn't matter what you call the files in the directory, every precompiled header in the directory will be considered. The first precompiled header encountered in the directory that is valid for this compilation will be used; they're searched in no particular order.
There are many other possibilities, limited only by your imagination, good sense, and the constraints of your build system.
A precompiled header file can be used only when these conditions apply:
The -D option is one way to define a macro before a
precompiled header is included; using a
#define can also do it.
There are also some options that define macros implicitly, like
-O and -Wdeprecated; the same rule applies to macros
defined this way.
-fmessage-length= -fpreprocessed -fsched-interblock -fsched-spec -fsched-spec-load -fsched-spec-load-dangerous -fsched-verbose=number -fschedule-insns -fvisibility= -pedantic-errors
For all of these except the last, the compiler will automatically ignore the precompiled header if the conditions aren't met. If you find an option combination that doesn't work and doesn't cause the precompiled header to be ignored, please consider filing a bug report, see Bugs.
If you do use differing options when generating and using the precompiled header, the actual behavior will be a mixture of the behavior for the options. For instance, if you use -g to generate the precompiled header but not when using it, you may or may not get debugging information for routines in the precompiled header. | <urn:uuid:99d95943-5444-4d1c-8c41-3e64fbc61abf> | 3.40625 | 908 | Documentation | Software Dev. | 38.888079 | 95,638,073 |
Truly Intelligent Machines: The Impact of AI That Can Think
Intelligent machines are one of the most controversial types of technology in development today. And I hate to break it to those of you who are concerned about the use of AI-powered robots, but intelligent machines aren’t going anywhere. In fact, they’re only getting smarter.
Recently, leaders like IBM and Alphabet have been pushing AI to its outer limits, teaching it to not only master processes or answer simple questions, but to actively engage in arguments and develop its own “imagination.” In essence, technologists are trying to teach intelligent machines to do the things that—in the past—techies have assured us only humans can do.
And right now, it seems they’re being trained to do just about everything.
Arguments for Intelligent Machines
If you ask IBM, I’m sure they would say their Project Debater technology could be a huge benefit to the human population, especially in the business world. In a recent live debate, an AI machine was able to argue in favor of space exploration being publicly subsidized. Not only that, the machine was able to make an intelligent rebuttal to its opponent’s argument and craft a closing statement on its own. Imagine having the ability to use AI to develop arguments in favor or against a certain business deal, new hire or product launch? Brilliant!
The thing that concerns me about Project Debater isn’t so much its ability to make an argument. (As of now, the AI simply crafts a statement based off information it finds on Wikipedia—hardly a threat to world safety.) The more concerning point for me is that the AI has no idea what it’s talking about. As such, it has no ability to make a value judgement—something that, at this point, only humans can and should do. Without that ability, the technology could be powered to cause turmoil online, be it through cyber-bullying or security threats or simply leading businesses down a value-less rabbit-hole of “reasoning.”
Intelligent Machines: Thinking Like Humans?
If you are worried about intelligent machines’ lack of value systems, fear not: researchers are also working on building other human qualities into AI moving forward. Some for instance, believe they can teach robots “common sense,” working to find ways to help AI learn like a human baby learns—with instincts that guide its learning. They feel confident robots will be able to learn the concepts of causality (if I do this, that will happen); cost/benefit (value judgment of which has more positives than negatives); and even types vs. instances (the ability to recognize that something is “mine,” rather than something that belongs to everyone. The values in business would be—well, transformational. Rather than simply speeding up processes or helping companies automate, they could actually lead companies in new directions—better than their own leaders do.
Scared yet? You probably should be.
Arguments Against Intelligent Machines
I can understand researchers’ desire to code “instincts” into AI. After all, the world is a chaotic place. For bots to be remotely useful, they’ll need to be able to adapt in the moment just like a human would. They need to be able to make reasonable judgment calls—judgment calls that we as humans can trust to be in our best interest, or the interest of those we love.
Alphabet’s DeepMind, for instance, is developing technology that can look at just a few angles of an object—or eventually a situation—and be able to “imagine” what the other angles look like. In essence, it helps bots “fill in the blanks” to get a better idea of what they’re facing in a particular environment or situation. Still, is that really enough to guarantee that intelligent machines will continue to work for the benefit of humanity—even if and when they eventually outsmart us?
Many, including tech genius Elon Musk, say “no.” In fact, Musk has actually been one of the most outspoken opponents of AI-powered robots, arguing that they are a “fundamental risk to the existence of civilization.” Why? Because none of us really know how AI works—and if we don’t know how it works, we’ll have our hands tied if we ever need to stop it.
If I were to make a closing argument to Project Debater, it would be this: intelligent machines have a lot of power. But they should never have more than humans do. All of us—technologists and business people alike—would do well to remember this.
Latest posts by Daniel Newman (see all)
- Five Fixes for Your Failing Data Initiatives - July 19, 2018
- A War With Amazon: Walmart Looks To Microsoft To Accelerate Digital Transformation - July 18, 2018
- Broadcom to Acquire CA Technologies: $18.9 Billion Deal - July 12, 2018 | <urn:uuid:a262171a-363c-471e-aaf5-05a8fc9aeb25> | 2.75 | 1,050 | Personal Blog | Science & Tech. | 44.68483 | 95,638,075 |
A pure Python Steganography module.
Stegano, a pure Python Steganography module.
Steganography is the art and science of writing hidden messages in such a way that no one, apart from the sender and intended recipient, suspects the existence of the message, a form of security through obscurity. Consequently, functions provided by Stegano only hide messages, without encryption. Steganography is often used with cryptography.
$ pipenv install Stegano ✨🐍✨
You will be able to use Stegano in your Python programs.
If you only want to install Stegano as a command line tool:
$ pipsi install Stegano ✨🍰✨
pipsi installs scripts (system wide available) provided by Python packages into separate virtualenvs to shield them from your system and each other.
A tutorial is available.
Use Stegano as a library in your Python program
If you want to use Stegano in your Python program you just have to import the appropriate steganography technique. For example:
>>> from stegano import lsb >>> secret = lsb.hide("./tests/sample-files/Lenna.png", "Hello World") >>> secret.save("./Lenna-secret.png") >>> >>> clear_message = lsb.reveal("./Lenna-secret.png")
Use Stegano as a command line tool
Hide and reveal a message
$ stegano-lsb hide -i ./tests/sample-files/Lenna.png -m "Secret Message" -o Lena1.png $ stegano-lsb reveal -i Lena1.png Secret Message
Hide the message with the Sieve of Eratosthenes
$ stegano-lsb-set hide -i ./tests/sample-files/Lenna.png -m 'Secret Message' --generator eratosthenes -o Lena2.png
The message will be scattered in the picture, following a set described by the Sieve of Eratosthenes. Other sets are available. You can also use your own generators.
This will make a steganalysis more complicated.
Running the tests
$ python -m unittest discover -v
Running the static type checker:
$ python tools/run_mypy.py
Contributions are welcome. If you want to contribute to Stegano I highly recommend you to install it in a Python virtual environment with pipenv.
- Fixed an encoding problem which occured on Windows during the installation of the module.
- Stegano is ready for use with pipenv and pipsi.
- the recommended way to install Stegano is now to use pipenv.
- Fixed a bug with the new ‘encoding’ function when using Stegano as a command line tool. No default value was set. Default value is UTF-8.
- it is now possible to specify the encoding (UTF-8 or UTF-32LE) of the message to hide/reveal through the command line;
- the help of the command line now displays the available choices for the arguments, if it is necessary (list of available encodings, list of available generators);
- tests expected results lies now in a dedicated folder;
- a script has been added in order to get proper exit code check for mypy.
- updated command line. All commands are now prefixed with stegano-;
- improved type hints;
- it is possible to load and save images from and to file objects (BytesIO);
- improved checks when revealing a message with the lsbset module fails.
- improved generators for the lsb-set module;
- improved tests for the generators;
- improved type hints.
- unicode is now supported. By default UTF-8 encoding is used. UTF-32LE can also be used to hide non-ASCII characters. UTF-8 (8 bits) is the default choice since it is possible to hide longer messages with it.
- improved checks with type hints.
- introduces some type hints (PEP 484);
- more tests for the generators and for the tools module;
- updated descriptions of generators;
- fixed a bug with a generator that has been previously renamed.
- bugfix: fixed #12: Error when revealing a hidden binary file in an image.
- bugfix: added missing dependency in the setup.py file.
- improved docstrings for the desciption of the generators;
- improved the command which displays the list of generators.
- added a command to list all available generators for the lsb-set module;
- test when the data image is coming via byte stream, for the lsb module.
- a command line for the ‘red’ module has been added;
- bugfix: fixed a bug in the lsb-set command line when the generator wasn’t specified by the user.
- Support for transparent PNG images has been added (lsb and lsbset modules).
- bugfix: solved a bug when the image data is coming via byte streams (ByteIO), for the exifHeader hiding method.
- reorganization of the steganalysis sub-module.
- improvements of the command line of Stéganô. The use of Stéganô through the command line has slightly changed (‘hide’ and ‘reveal’ are now sub-parameters of the command line). No changes if you use Stéganô as a module in your software. The documentation has been updated accordingly.
- bugfix: Incorrect padding size in base642string in tools.base642binary().
- the generator provided to the functions lsbset.hide() and lsbset.reveal() is now a function. This is more convenient for a user who wants to use a custom generator (not in the module lsbset.generators).
- performance improvements for the lsb and lsbset modules.
- reorganization of all modules. No impact for the users of Stegano.
- improvements and bug fixes for the exifHeader module;
- added unit tests for the exifHeader module;
- improvements of the documentation.
- minor improvements and bug fixes;
- added unit tests for the slsb and slsbset modules.
- management of greyscale images.
- bugfix when the length of the message to hide is not divisible by 3, for the slsb and slsbset module.
- new project home page;
- minor updated to the documentation.
- bug fixes for Python 3;
- bug fixes in the scripts in ./bin.
- first stable release on PypI.
This release introduces a more advanced LSB (Least Significant Bit) method based on integers sets. The sets generated with Python generators (Sieve of Eratosthenes, Fermat, Carmichael numbers, etc.) are used to select the pixels used to hide the information. You can use these new methods in your Python codes as a Python module or as a program in your scripts.
- you can now use Stéganô as a library in your Python program; (python setup.py install) or as a ‘program’ thanks to the scripts provided in the bin directory;
- new documentation (reStructuredText) comes with Stéganô.
- this release introduces some bugfixes and a major speed improvement of the reveal function for the LSB method. Moreover it is now possible to hide a binary file (ogg, executable, etc.);
- a new technique for hiding/revealing a message in a JPEG picture by using the description field of the image is provided. | <urn:uuid:225fc7f9-4b36-4a2d-872e-a89ab4fb7bf9> | 2.78125 | 1,646 | Documentation | Software Dev. | 46.468765 | 95,638,093 |
In experiments with mice genetically prone to develop polyps, researchers discovered that animals carrying one copy of the damaged gene, Atp5a1, had about 90 percent fewer polyps in the small intestine and colon. Because people with large numbers of such polyps are at significantly higher risk to develop colon cancer, the finding may provide new ways to diagnose, prevent and treat colon cancer, the scientists say. They report their findings March 22, 2007 online in the journal Genome Research.
The researchers, led by Arthur Buchberg, Ph.D., and Linda Siracusa, Ph.D., both associate professors of microbiology and immunology at Jefferson Medical College of Thomas Jefferson University in Philadelphia, studied a type of mice called Min (multiple intestinal neoplasia). Such mice carry mutations in the Apc gene, which causes the development of intestinal tumors in mice. An alteration in the corresponding human gene, APC, is the first step in most cases of the development of colon polyps and the majority of colorectal cancers.
It turns out that Atp5a1, which is crucial for the cell’s energy production, is also a “modifier” gene. Modifier genes play roles in individual susceptibility to cancers. “Modifier genes alter a phenotype dictated by other genes,” explains Dr. Siracusa. “If a person inherits a mutation in the APC gene, a modifier gene can make that number of polyps – and tumors – either higher or lower, and can mean a person is more prone or resistant to developing polyps and tumors.”
In earlier work, the husband and wife team had identified the general region on the chromosome for the mutation. “Now, we’ve identified the gene and it’s very important – it encodes a subunit of the ATP synthase protein, which is known as the molecular motor in the mitochondria, and responsible for the production of ATP and energy in cells,” says Dr. Buchberg. They have dubbed Atp5a1 “Mom2,” for Modifier of Min 2 gene, having previously identified the first modifier of Min mice, Mom1.
“No one as far as we know has ever found a mutation in this gene,” says Dr. Siracusa, noting that both gene mutations – Apc and Atp5a1 – are on mouse chromosome 18. “If the other normal chromosome is lost for some reason, or mice have two copies of the mutant Atp5a1, they die in embryonic development, presumably because the cells lack an energy source.”
The corresponding human gene, ATP5A1, is also located on chromosome 18, in a region that sometimes shows genetic mutations in colon tumors.
Steve Benowitz | EurekAlert!
Barium ruthenate: A high-yield, easy-to-handle perovskite catalyst for the oxidation of sulfides
16.07.2018 | Tokyo Institute of Technology
The secret sulfate code that lets the bad Tau in
16.07.2018 | American Society for Biochemistry and Molecular Biology
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
16.07.2018 | Physics and Astronomy
16.07.2018 | Life Sciences
16.07.2018 | Earth Sciences | <urn:uuid:36fb720f-55b1-4ad3-91fc-1a472f50b558> | 3.328125 | 1,231 | Content Listing | Science & Tech. | 39.757688 | 95,638,135 |
How long does the stone fall freely into a depth of 80m? What speed will it hit the bottom of the abyss?
Leave us a comment of example and its solution (i.e. if it is still somewhat unclear...):
Showing 0 comments:
Be the first to comment!
To solve this example are needed these knowledge from mathematics:
Next similar examples:
The aircraft flies at an altitude of 4100 m above the ground at speed 777 km/h. At what horizontal distance from the point B should be release any body from the aircraft body to fall into point B? (g = 9.81 m/s2)
The car accelerates at rate 0.5m/s2. How long travels 400 meters and what will be its speed?
- Speed of sound
The average speed of sound is 330 meters per second. Estimate how long it will hear the church bell 1 km away. Calculate the distance from what would hear sound after 10 seconds.
From Znojmo to Brno started truck with a trailer at an average speed 53 km per hour. Against him 14 minutes later from Brno started car with an average speed of 1.2-times greater than the truck. How long and how far from Znojmo, they meet if the distanc
- Train 2
The train slowed down from 90 km/h to 72 km/h in 5 seconds. How long track travel?
Stone was pushed into the abyss: 2 seconds after we heard hitting the bottom. How deep is the abyss (neglecting air resistance)? (gravitational acceleration g = 9.81 m/s2 and the speed of sound in air v = 343 m/s)
Shot with a mass 43 g flying at 256 m/s penetrates into the wood to a depth 25 cm. What is the average force of resistance of wood?
Calculate the wavelength of the tone frequency 11 kHz if the sound travels at speeds of 343 m/s.
At what horizontal distance reaches the car weight m = 1534 kg speed v = 85 km/h when the car engine develops a tensile force F = 1691 N. (Neglect resistance of the environment.)
- Circular motion
Mass point moves moves uniformly in a circle with radius r = 3.4 m angular velocity ω = 3.6 rad/s. Calculate the period, frequency, and the centripetal acceleration of this movement.
What overload in g (g-force) has passed the pilot if he accelerated from 0 to 600 km/h in 3 seconds?
- Theorem prove
We want to prove the sentense: If the natural number n is divisible by six, then n is divisible by three. From what assumption we started?
- G forces
Calculate deceleration of car (as multiple of gravitational acceleration g = 9.81 m/s2) which occurs when a car in a frontal collision slows down uniformly from a speed 111 km/h to 0 km/h in 1.2 meters trajectory.
- The cruise ship
The cruise ship has a speed of 12 km / h at a calm surface. When we sail 45 km along the river and 45 km back, it took us exactly 8 hours. Which (constant) speed of flow of the river?
Flywheel turns 450 rev/min (RPM). Determine the magnitude of the normal acceleration of the flywheel point which are at a distance of 10 cm from the rotation axis.
- Parametric equation
Find the parametric equation of a line with y-intercept (0,-4) and a slope of -2.
- Third member
Determine the third member of the AP if a4=93, d=7.5. | <urn:uuid:26cb6168-23a4-4b0e-8b40-5f397af38698> | 2.625 | 784 | Tutorial | Science & Tech. | 84.802691 | 95,638,148 |
This paper shows an example of substantial increase in carbon emissions from forest fires after reforestation on a national scale. It is the first estimation of historical carbon emissions from forest fires in Korea during the last 40 years. Investigation was focused on the recent increase in large forest fires and its closely related factors. A simple modeling approach to estimate carbon emission was applied. The direct carbon emission from forest fires in 2000, ranging from 115 to 300 Gg C, corresponds to 1-3% of the annual carbon uptake by forests. The influence of forest fires on the carbon cycle in Korea is not so significant, but Korean forests have a large potential for generating severe local fires due to increasing forest carbon density and a high forest area ratio (forest area/total land area) of 65%. The carbon emission per area burned (Mg C ha- 1) clearly reflects the trend toward increases in the number of severe fires. Statistical analyses and the trends of annual temperature and precipitation show that the recent large increase in carbon emissions may be the negative consequences of intensive forest regrowth that is the product of successful reforestation and forest management programs rather than the effect of climate change. These results imply a need for further studies in other countries, where large-scale plantation has been conducted, to evaluate the role of plantation and forest fires on the global carbon cycle. © 2006 Elsevier B.V. All rights reserved.
Mendeley saves you time finding and organizing research
Choose a citation style from the tabs below | <urn:uuid:2d980c5a-4631-4afc-b39c-3a3b27ae790d> | 3.234375 | 298 | Academic Writing | Science & Tech. | 34.35875 | 95,638,149 |
Range & Status
A widespread species in Europe, but largely found in southern Britain. Very local, probably increasingly scarce through habitat degradation and loss, but also probably underrecorded.
Old reports from the Lizard and West Penwith, but only recently found on Carvear Moor, St. Blaise, in 1991 and Colvannick Pond, Bodmin Moor in 2004. Probably many more sites await discovery.
Habitat & Ecology
A wetland species, occurring amongst dense wet vegetation in shallow water or at water margins, amongst Sphagnum spp. in bogs and at the margins of acid pools, in fens, ditches, and seepages on soft rock cliffs.
Drainage and infilling of wetlands.
Protection of old wetlands is required. | <urn:uuid:8d4caa81-f423-4a67-a3f5-b9f2cb0cedc5> | 2.90625 | 162 | Knowledge Article | Science & Tech. | 45.821667 | 95,638,172 |
Subjective Questions of Thermodynamics
Two thermally insulated vessels are filled with equal number of moles of air and connected by short tube with a value. If P, V and T and pressure, volume and temperature of gas in first vessel and 2P, V and T / 2 be pressure, volume and temperature of gas second vessel then find temperature and pressure of air after opening the value.
Calculate the heat absorbed by the system in going through one cycle for the cyclic process
shown in the Figure
when water is boiled under a pressure of 2 atm, the heat of vaporization is 2.20 x 106
and the boiling point is 120 °C. At this pressure 1 Kg of water has a volume 10-3
, and 1 kg of steam a volume of 0.824 m3
(a) Compute the work done when 1 kg of steam is formed at this temperature
(b) Compute the increase in internal energy
Figure below shows different paths. connecting state i to state f in P-V diagram along which gas can be taken Rank paths according to
(a) Change in internal energy
(b) Work done by gas
(c) The magnitude of energy transferred as heat.
Two moles of helium (γ=5/3) are initially at a temperature of 27 °C and occupy a volume of 20L. The helium is first expanded at constant pressure until the volume has tripled, and then adiabatically until the temperature returns to its initial state. given for helium
= 20.78 J/mol-k
(a) Draw diagram of process is P-V plane
(b) What is the total heat supplied in the process
(c) What is the total change in internal energy of helium.
(d) What is the total work done by the helium.
(e) What is the final volume and pressure.
Temperature of a system containing 1 mole ideal gas increases by on amount ΔT = 30 K as a result of heating at constant pressure. If gas obtains an amount of heat Q= 3.2 KJ. then calculate
(a) work done by the gas
(b) change in its internal energy
(c) value of γ= Cp
Two moles of a certain ideal gas at a temperature T0
= 300K were cooled isochorically so that the gas pressure reduced two times. Then as a result of the isobaric process the gas expanded till its temperature get back to the initial value.
(a) What would be total change in internal energy.
(b) Total work done by the system.
(c) Find the total amount of heat absorbed by gas in this process
An ideal gas where adiabatic exponent is equal to γ, is expanded so that the amount of heat transferred to the gas is equal to the decrease of internal energy find
(a) molor heat capacity of gas in this process
(b) equation of process in variables T, V
(c) Work performed by one mole of gas when its volume increases by η time if T0
is the initial temperature of the gas.
An ideal gas is taken from an initial state i to a final state f in such a way that the ratio of the pressure to the absolute temperature remains constant. What will be the work done by the gas.
Consider the cyclic process ABCA, shown in the Figure, performed on a sample of 2.0 mole of an ideal gas. A total of 1200 J of heat is withdrawn from the sample as the process. Find the work done by the gas during the part BC.
Consider a cylindrical tube of volume V with adiabatic walls containing an ideal gas. The internal energy of this ideal gas is given by 1.5 μRT. The tube is divided into two equal parts by a fixed diathenic wall. Initially, the pressure and the temperature are P1
on the left side and P2
right. The system is left for sufficient time so that the temperature becomes equal on the two sides.
(a) How much work has been done on the left part.
(b) Find the final temperature on the two sides.
(c) Find the final pressure on the two sides.
1 moles of an ideal gas whose adiabatic exponent equals y undergoes a process in which gas pressure relates to the temperature as
where a is constant.
If the temperature get an increment of ΔT,find following
a. Change in Internal energy
b. Work performed by the gas
c. Molar heat capacity of the gas in the process
d. find the amount heat supplied
Two vessels A & B of equal volumes V0
are connected by the narrow tube which can be closed by the valve. The vessels are fitted with the piston which can be moved to change the volumes.Intially the valve is open and vessel contains ideal gas whose adiabatic exponents is Y at atmosphere pressure P0
and atmosphere temperature T0
.The walls of the vessel A are adiabatic while the walls of the vessels B are diathermic. The valve is now closed and piston is slowly moved to triple the original volume.
a. Find the temperature and pressure in the two vessels.
b The valve is now open for sufficient time so that gases acquire a common temperature and pressure. Find the new values of pressure and temperature
1 mole of an ideal gas whose adiabatic exponents is Y is enclosed in the vertical adiabatic vessel fitted with moving frictionless piston whose weight is W and cross-sectional area is A.The atmospheric pressure is P0
.Intial volume is V0
.Heat is supplied to the gas to double its volume.
a. Find the initial and final state of the gas
b. Find the work done by the gas
C. Find the change in internal energy
Two samples A and B whose adiabatic exponents is Y are initially kept in the same state (P0
).Now sample A is expanded such that volume becomes 2V0
and Q=0 for the process. Sample B is expanded such that volume becomes 2V0
and ΔU=0 for the process
a. Find the ratio of the final pressure of the two samples
b. Find the ratio of the final temperature of the two samples
c. Find the ratio of the work done by the two samples
One mole of an ideal monoatomic gas is taken round the cyclic process ABCDA as shown in figure.
a. Work done by the gas
b Heat absorbed by the gas in AB and BC
c. Heat in process CD
d. Find the temperature at C and D
e. Maximum temperature attained by the gas during the cycle
f. Net change in the internal energy and the heat
An ice cube of mass .1kg at 0 °C is placed in an isolated container which is at 227° C. The specific heat of the container varies with temperature according to the empirical formula
S=A + BT
where A is 100cal/kg-K and B is 2x10-2
if the final temperature of the container is 27°C.Determine the mass of the container.
Specific heat of water is 103
Latent heat of fusion of water is 8x104
A gaseous mixture is such that
No of moles
The gaseous mixture is taken through an adiabatic process where temperature of the mixture drops by ΔT.
a. Find the work done by the mixture
b. If m1
are the relative molecular mass of the gas A and B respectively. Find the speed of sound in the mixture at Temperature T0
A diatomic gas whose adiabatic coefficient is y=1.4 is taken through XYZAX cycle.
X->Y Adiabatic compression
Y->Z Isobaric expansion
Z->A Adiabatic expansion
A->X Isochoric process
find the following
- Molar heat capacities in each process
- if the volume ratio is VX/VY=16 and VZ/VY=2 and TY=636° C
a. find the heat absorbed in the process Y->Z
b. find the net work done by the gas in the cycle
c. find the ratio of pressure PY
Class 11 Mathse
Class 11 Physics | <urn:uuid:c5b44f05-e85d-4f1b-b9f4-186259f42392> | 3.8125 | 1,760 | Tutorial | Science & Tech. | 64.377614 | 95,638,193 |
Under global climate change, the montane tropical rainforests of north-eastern Australia are expected to shrink considerably, reducing the potential ranges of the 13 endemic bird species they support. An increase of just 1°C will reduce their mean range by over 30%, and the number of extinctions will increase dramatically if temperatures rise by more than 2°C; almost all species will go extinct if temperatures rise by 5.8°C.
The montane tropical rainforests of north-eastern Australia support 13 endemic bird species. Under global climate change, these forests are expected to shrink considerably. An increase of just 1°C (considered inevitable within the next few decades) will reduce the mean range of endemic birds by over 30%, as suitable climate space retreats to higher altitudes up mountain sides. The reduction may be as much as 96% if temperatures rise 3.5°C. Assuming that the complete loss of a species’s suitable range results in its extinction (because there will be no areas of new suitable habitat to disperse to), the number of extinctions will increase dramatically if temperatures rise by more than 2°C, and almost all species will go extinct if temperatures rise by 5.8°C (the upper end of the predicted range of temperature increases; S. Williams in litt. 2003, Houghton et al. 2001; see figure). These results are mirrored for other endemic vertebrates (Williams et al. 2003), and dramatically illustrate the need for action to ensure that temperature rises do not exceed c.2°C. If they do, the results for biodiversity will be catastrophic.
Compiled: 2004 Copyright: 2004
BirdLife International (2004) The number of montane endemic birds that go extinct in Australia depends on the degree of warming. Downloaded from http://www.birdlife.org on 23/07/2018 | <urn:uuid:43c82a63-5373-4322-b8cc-a7768b6f1bbc> | 4.15625 | 380 | Knowledge Article | Science & Tech. | 49.053159 | 95,638,198 |