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Working with Characters and Text
The discussion thus far has focused on looking at key components of the Dreamweaver 4.0 environment to facilitate a fast development of a web page. We have seen how the Layout and Standard views on the Objects panel provide a convenient way of planning and designing a page. Through this, the important role of tables for page layout has been identified and their usage explained.
KeywordsFont Size Text Block Text Colour Main Menu Colour Palette
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Toevaluate the influence of the velvet-like surface mimicking the structure on the suction side of barn owl wings on the flow field and on the aerodynamic performance of the wing, high-speed particle image velocimetry and time- resolved force measurements were performed. The Reynolds number was varied in the range of 40;000 ≤ Rec ≤ 120;000, and the range of the angles of attack was 0 ≤ α ≤ 6 deg for the particle image velocimetry measurements and −15 ≤ α ≤ ?20 deg for the force measurements. The flow over a clean-wing model whose geometry corresponds to that of the owl wing without any special adaptations was investigated as a reference case for the same Reynolds number and angle of attack range. This clean wing possesses a laminar separation bubble as the dominant flow feature. Two artificial surfaces were selected to mimic the natural surface concerning the length, density, and thickness of the filaments. The surfaces were able to reduce flow separation. Although this reduction of the separation region might have a positive influence on the pressure drag, the aerodynamic performance of the models with the artificial surfaces was significantly reduced due to the increased skin-friction drag. Furthermore, the models equipped with the velvets possessed a reduced susceptibility to changes in Reynolds number and angle of attack concerning the aerodynamic performance. It can be stated that the velvet surfaces stabilize the flow field at low Reynolds numbers, enabling the owl to fly more slowly and thus more silently.
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Bohrs Atomic Model
It is introduced by Danish Physicist Niels Bohr in the year of 1913. According to this model the atom consists of small nucleus at the center and electrons which rotates in circular orbits surrounding the nucleus - similar to solar system. But here, the force of attraction is provided by electrostatic forces rather than gravitational forces. The nucleus is positively charged and electrons are negatively charged. Further Niels Bohr illustrated that the positively charged nucleus consists of protons and neutrons. The protons are positively charged and neutrons does not have any charges. Niels Bohr introduced the quantum theory to overcome the drawbacks of Rutherford’s atomic model. According to this theory –
- Electrons revolves around the nucleus in certain orbits. Each orbit is having certain energy level. These orbits are called stationary orbits. The orbit near to nucleus is having low energy level and the outer orbit is having higher energy level.
An electron can revolves in certain energy level without losing any energy. On addition of energy to the atom, the electron jumps to orbit of higher energy level. On the other hand, when electron jumps from the orbit of higher energy level to the orbit of lower energy level, the electron release the energy in small packets. These small packets are called the quanta or photons. The energy of photon is given by,
‘h’ is the plank’s constant,
'υ' is the frequency of light (in Hz),
‘c’ is the speed of light (in m/sec),
‘λ’ is the wave length of light emitted (in meter).
- The centripetal force due to electrostatic attraction between positively charged nucleus and negatively charges electron is equal to the centrifugal force of electron moving in circular orbits.
- The angular momentum of electron moving in circular orbits is the integral multiple of Where, n is an integer called quantum number.
- The radius of the orbit is proportional to n2 and the velocity of electron is inversely proportional to n. These assumptions led to results which have been found correct of being tested.
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This model is also having some deficiency which are listed below-
- It is applied to one electron atom i.e. hydrogen atom. It cannot be easily extended to explain the more complicated atoms.
- It does not give any rule or restriction regarding the transition of an electron from one orbit to another orbit.
- It introduced only one quantum number n. Whereas, experimental evidence concerning fine structure of spectral line suggests the more additional quantum numbers.
- The quantitative explanation of chemical bonding cannot be explained by the Bohr’s atomic model. | <urn:uuid:2073a6fd-164b-434b-9e7f-4cdb1d800566> | 3.875 | 551 | Knowledge Article | Science & Tech. | 37.158899 | 95,550,159 |
It is an object of this Chapter to remove some of the mystique associated with generalized functions and to advocate their use in the analysis of physical problems. We will define their properties without proof and direct those interested in pursuing the fundamentals of generalized functions to Lighthill (1958), Gelfand & Shilov (1964) and Jones (1966) who give comprehensive accounts of the general theory with proofs of properties. We lean heavily on these works in recognizing that generalized functions can essentially be manipulated according to the usual rules of addition, differentiation and integration, though in general they may not be multiplied by other than ordinary functions. They provide a powerful extension of the normal mathematical equipment available to physicists.
KeywordsGreen Function Delta Function Helmholtz Equation Good Function Integral Property
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Check out beautiful Bachelor Pond in Miami University's Bachelor Preserve. (Quicktime movie~1.6 mb).
Thousands of feet below the surface, the waters of the ocean are cold, still, and dark. Almost no sunlight can penetrate such depths, and the water temperature hovers near freezing. The harsh conditions of the abyss have generated some of the most nightmarish bizarre-looking creatures on Earth. Here there is a need for a cool light that will help organisms find their way through the dark murky waters, this light that is produced from a cool chemical reaction unlike sunlight (which is thermal) or electrical light is know as bioluminescence. Bio means living and luminescence means Ňgiving off light.Ó Luminescent organisms give off different types of light and not all organisms use their luminescence the same way. Some luminescent organisms use their light all of the time, or receive the light from bacteria growing on their bodies. Others flash their light(s) on and off whenever they choose. These lights are used to communicate, to camouflage, to guide, to attract mates, to lure prey, and sometimes to frighten enemies. The many animals and organisms that produce this glow are generally found in the deep sea or in shallow ocean waters at night, but also can be found in caves, grasslands, forests, and even in your own backyard.
In the ocean, bioluminescent organisms are everywhere, inhabiting all the depths and covering all the world's oceans. The most common organism which uses bioluminescence, dinoflagellates, can be found virtually everywhere in the sea. This phytoplankton (plant-like microscopic organisms) gathers by the thousands to create red tides. This name coming from the red-brown color that overwhelms the oceans do to their immense numbers. These organisms produce streaks of electric blue light that highlight breaking waves during the night. The red tide phytoplanktons use their flashes as a type of security alarm to avoid being eaten. Any stimulation of the cells creates flashes of light which is intended to scare away predators.
The ocean currents hold countless tiny swimming and floating organisms called dinoflagellates. These creatures appear greenish white. The largest dinoflagellates is about 1 millimeter, which is about the size of the period at the end of this sentence. At night, when they are disturbed by passing boats, fish, or heavy waves, they sparkle like jwels. Even a bubble pushing on them causes their tiny membranes to change shape and emit light. These dinoflagellates exit mostly in salt water. They are found in many shapes, some even with protective plates or shells. They get their food from dissolved scraps of leftovers from larger fish.
One well-known area to see luminescent dinoflagellates is in Puerto RicoŐs Phosphorescent Bay, on the islandŐs southwest coast. The 60 acre lagoon is attached through a narrow link to the CaribbeanŐs gentle tides and vitamin-rich water. Every night of the year this bay is said to produce an erie glow. Millions of microorganisms produce billions and billions of chemical reactions and turn the ocean waters into a giant nightlight. In this bay, even dipping your hand in the water supposedly causes it to glow like a ghost.
Most Caribbean phosphorescent bays have been destroyed by buildings on the coastland. Commercial development had changed the waterŐs quality, quantity, and nutrient supply. The most recent study available in 1987 in a U.S. Navy report, saw only 14 phosphorescent bays left in the world. No extreme measures have been focused on the preservation these dinoflagellates or the glowing bays, but currently seem to be thriving. People never seem to worry about thriving organisms, but perhaps in the years ahead there will be more attention on these little guys.
Moving downward, in the perpetual darkness of the deep sea, where sunlight never reaches bioluminescence serves other purposes. Anglerfish grow luminescent bacteria in a special structure which dangles at the end of a stalk projecting from their forehead. This stalk is a modified spine from the dorsal fin called an illicium. Just as fishermen use a glowing lure for night fishing, in the perpetual darkness of the deep sea these fish attract prey by their glowing lures. Some deep-water anglerfish can catch and eat prey as much as three times their length. Of deep-water pelagic fish, the anglerfish are the most diverse. They are sometimes smooth-skinned, sometimes spiny, generally of a velvety-black complexion.
The ocean is a very vast and open space. Keep in mind that water makes up 73% of the earth. The ocean is first divided into two separate categories. Benthos refers to the bottom of the ocean and the organisms living there. We will focus more on the open water. The uppermost layer of the open ocean is called the epipelagic, or eutrophic (good light) zone. It begins at the surface and ends as deep as 650 feet. Beneath this surface layer - from depths of 650 to 3300 feet - is the mesopelagic, of disphotic (bad light) zone. At the bottom of the pelagic sea is the aphotic (without light) zone, between 3300 feet and the sea floor.
The epipelagic zone is a clear well-lighted place, a region where fish like the tuna, the king fish, the sailfish, the marlin exist. Underneath, far more voluminous, is the mesopelagic zone of dimness and dark, inhabited by mid-water squid and fish of habits weird and aspects strange. This is a transition zone. It is the floor of the zone of light, the ceiling of darkness. It is inhabited by creatures with exquisitely photosensitive eyes and bodies spangles with photophores and luminescent splotches. "In mesopelagic fish, eyes are generally large to enormous, with retnas composed entirely of rods for detection of light. Photopores are often large and numerous, central nervous system fairly well developed, sense of smell moderately acute, skeleton well ossified, muscles well developed, swim bladder usually present, gills filamentous, heart and kidneys large. In fish of the deeper, dark zones, eyes are small, photophores are small, central nervous system weakly developed, skeleton weakly ossified, muscles poorly developed, swim bladder absent or regressed, gills reduced, heart and kidneys small" (Brower pp39) The number and diversity of inhabitants are greater here than in any of the layers below; until one reaches the bottom.
There are basicly three different types of luminescence found in organisms, all of which are found in species of squid. Internal luminescence is light produced within the tissues held by special cell structures called photophores. External luminescence is light produced in the water through secretions ejected from the squid. And Bacterial luminescence is light produced on the skin of the squid by colonies of luminescent bacteria living actually on the surface of the squid. While these are three different ways luminescence is exhibited, the chemical reaction is still the same.
Bioluminescent light differs from electric light and light from fire and the sun, which are warm. Bioluminescent light is a cold light. It comes from two chemical substances, luciferase and luciferin which exist inside or on the bodies of these glowing organisms. These chemicals react with oxygen and ATP to produce light. ATP (adenosine triphosphate) is a chemical energy found in all living things.
During hot summer evenings you may see flickering yellow or green lights in your back yard. These insects are known as fireflies, but they are not really flies. They are beetles with light organs under their tails.
The fireflies, or lampyrids, that you see blinking are mostly males who are searching for a mate. Each species has its own code. The male blinks his half of the code and the female, usually perched on a blade of grass, answers with the other half. There are more than 2000 species of fireflies throughout the world, each with itŐs own code. Fireflies are found on every continent except Antarctica.
The majority of humans may overlook the luminescent glow of these bioluminescent organisms, but scientists have not. More than 80% of all ocean animals show some form of luminescence and medical research has benefited greatly from these organisms by using the special chemicals of luciferase and luciferin. These chemicals have been found to help to detect disease in humans. Bacteria consist of a high amount of ATP (adenosine triphosphate). When a blood or urine sample from an ill person is combined with these chemicals, it will glow brightly if there is bacteria present, showing infection. Cancer cells and tissue damage from a heart attack can be detected by injecting these chemicals into the suspected disease area. Contamination of water, soft drinks, and wines also can be detected by adding a mixture of luciferase and luciferin. The presence of bacteria or yeast will cause the liquids to glow.
A gift from nature, these living lights are not only fascinating, but also lead to discoveries which have, and will continue to provide a better life for us all.
Brower, Kenneth. Realms of the Sea, The National Geographic Society;WashingtonD.C. 1991.
Ellis, Richard. Encyclopedia of the Sea. Random House; NewYork. 2000.
Holliday, Les. Ocean Life. Cresent Books; NewYork. 1991.
Presnall, Judith. Animals that Glow. First Books; NewYork. 1993.
Snydorman, Marty. Life in the Sea. Publications International, Ltd.; Lincolnwood, Illinois. 1994.
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Authors: Ricardo Gil
Let’s say one explodes a Russian TSAR in the cold spot. This would be a literal big bang and create some form of universe. Conversely a hot quantum particle could or may have caused the big bang even at equilibrium because it pops into the cold spot in the universe. Think weather, hot and cold front equals a turbulent thunder storm or violent weather patterns or conditions.
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New Delhi: Nature has its own way of doing things. An interesting research has suggested that a Japanese volcano that previously erupted in the year 1914, is gearing up for a blast in the coming few decades.
Sakurajima volcano is an active composite volcano and a former island in Kagoshima Prefecture in Japan. Its eruption in 1914 caused the erstwhile island to merge with the Osumi Peninsula.
Now, it seems like the pool of liquid magma protruding beneath the volcano has been slowly mounting every year, which is a sure sign of threat.
"This big reservoir is growing, and it's growing at quite a fast rate," said study co-author James Hickey, a geophysical volcanologist at the University of Exeter's Camborne School of Mines in England, Live Science reported.
Going by the calculations, Sakurajima could erupt cataclysmically within approximately 25 years, according to the study.
Live Science further reported that, the new analysis could also help scientists forecast better when other big volcanoes could erupt, as per the researchers. | <urn:uuid:61dc4fc5-4a08-4e72-8b56-410a1559ca20> | 3.5 | 221 | News Article | Science & Tech. | 33.255164 | 95,550,213 |
The descriptions of ray paths in the microscope given in most books are insufficient to provide what is required for a proper appreciation of the roles of the various parts in a modern microscope. This chapter attempts to deal with ray paths in enough detail to illustrate the concepts of geometrical optics and the interrelation of lenses and diaphragms. The essential optical system described here exists in every microscope, but some are equipped with extra parts, optical and mechanical, for the measurement of optical and geometrical properties in various kinds of stage objects.
KeywordsLuminous Surface Virtual Image Primary Image Tube Lens Aperture Angle
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#Sciencedeskdigs: Dissecting Scope
We are travelling back in time this week on #sciencedeskdigs. Maria Caffrey, a climatologist who studies ancient microfossils like pollen, diatoms, and charcoal, tells us what we can learn from the past.
Tell us more!
I work mostly with ancient pollen. Researchers collect sediment cores from wetlands and lakes. Using specific chemicals, climatologists dissolve the sediment, leaving the pollen behind to study. We study the pollen to understand what the environment was like in the past. Then we use that knowledge to predict how the environment will respond to future changes.
This particular dissecting scope shows a rock that has a dendritic psilomelane (a manganese oxide) in it. Sometimes we find manganese oxides (that black stuff) in our cores. I also often use the dissecting scope to look at charcoal to ID what plants burned in the past.
By studying past climates through microfossils we can model future climates. Knowing future climates is important because we can predict potential floods or sea level rise which can greatly affect people. For example, I just mapped the sea level rise in our nation’s capital and now we will be able to predict any devastating events that may occur and warn people.
Describe your workspace in one word
Innovative. We are always trying to think of new ways to answer questions about past and future climates. | <urn:uuid:58193241-91db-4913-809f-1141f1e12461> | 3.515625 | 309 | Knowledge Article | Science & Tech. | 43.732485 | 95,550,240 |
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From the Editor: Seek and you will find
THIS INSIGHTFUL MESSAGE HAS GUIDED PEOPLE on life’s journey for millennia, and more recently it has undoubtedly led visitors to national parks in search of restoration, health, and well-being. It is also relevant to the study of biological diversity, the theme of this issue of Park Science and a subject of great importance to the future of national parks.
All life-forms, from the smallest virus to the largest marine mammal, help define, regulate, and maintain park ecosystems. Understanding the functions of these organisms—the roles they play in the production of soils, provisioning of water, storage and recycling of nutrients, breakdown of pollution, and many other ecological services—is at the core of our task in the National Park Service to preserve parks unimpaired for the enjoyment of future generations. The story of biodiversity in national parks is part discovery, part science, and part management, and we touch on all three areas in this issue. A series of articles describes the trend in parks to conduct activities devoted to the discovery of biodiversity. When we commit time and resources to the search for life, we find species that are new to parks and new to science, and we deepen our understanding of familiar species. How we manage the information that comes from this endeavor and incorporate it into park decision making is equally important and is also discussed in several articles.
Much of the science related to biodiversity study is the same today as it has been traditionally, though the pool of taxonomists we rely on to make identifications is shrinking. Additionally, our focus has shifted to invertebrates, nonvascular plants, and other less studied taxa and how we organize our fieldwork, subjects we explore in several articles. Techniques for collecting, processing, and documenting species and communicating about biodiversity are progressing with the help of academic and conservation partners and volunteers. Data analysis now makes it possible to predict locations for species of conservation interest, and synthetic biology has emerged as a means to create novel yet likely controversial alternatives to remedy species restoration and control problems.
In total we share more than 40 articles describing work to explore, understand, and integrate knowledge of biological diversity in national parks. I invite you to read the stories, weigh our progress, and contemplate next steps. You may even find something of value that you didn’t know you were looking for.
—Jeff Selleck, Editor
Suggested citation for this article
Selleck, J. 2014. From the Editor: Seek, and you will find. Park Science 31(1):1–2.
This article published
Online: 14 November 2014; In print: 25 November 2014
This page updated
22 December 2014
Back to Volume 31, Number 1
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Programmed cell death, or apoptosis, occurs tens of millions of times every day in every human body. Researchers in South Korea have devised an easy method to detect apoptotic cells by fluorescence, as they report in Chemistry—An Asian Journal.
Their method makes it easier to detect improper biological regulation of apoptosis, which can lead to neurodegenerative diseases, autoimmune diseases, and cancer.
Apoptosis is involved in macroscopic developmental processes as well. For example, in an embryo, the cells between fingers die by apoptosis to form individual digits, and the tail of a tadpole is resorbed by apoptosis when it metamorphoses into a frog.
Upon apoptosis, the relative composition of the outside and inside of the cell membrane changes, and one component, phosphatidylserine (PS), migrates from the interior to the exterior. Kyo Han Ahn and collaborators at Pohang University of Science and Technology designed an artificial membrane vesicle that fluoresces when it interacts with PS. This so-called liposome is held together by a polydiacetylene backbone and is decorated with zinc atoms at its periphery.
The zinc atoms interact with PS but not with other components of the cell membrane. This interaction distorts the shape of the backbone, causing fluorescence of the liposome. The "turn on" effect eliminates washing steps to remove extra fluorescent marker, making the method easy to use. The selectivity of the interaction means that only apoptotic cells are marked fluorescently. Microscopy images show that the fluorescence is localized on the cell surface, confirming the mode of interaction between liposome and PS.About the Author
Chemistry - An Asian Journal, Permalink to the article: http://dx.doi.org/10.1002/asia.201201139
Further reports about: > Cancer > Liposome > apoptotic cells > autoimmune disease > autoimmune diseases > biological functional materials > biological regulation of apoptosis > cell membrane > degenerative disease > information technology > luminescent materials > neurodegenerative disease > polydiacetylene backbone
Scientists uncover the role of a protein in production & survival of myelin-forming cells
19.07.2018 | Advanced Science Research Center, GC/CUNY
NYSCF researchers develop novel bioengineering technique for personalized bone grafts
18.07.2018 | New York Stem Cell Foundation
A new manufacturing technique uses a process similar to newspaper printing to form smoother and more flexible metals for making ultrafast electronic devices.
The low-cost process, developed by Purdue University researchers, combines tools already used in industry for manufacturing metals on a large scale, but uses...
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
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By: David Beerling and F Ian Woodward
405 pages, 69 col plates, figs, tabs, maps
The authors demonstrate that the role of vegetation in the terrestrial carbon cycle during this time can be analysed by considering the key elements of present day vegetation processes linked to models of the global climate during different geological eras.
'The book is pioneering, thought provoking and scholarly ! if you are interested in plant-atmosphere interactions, then the book is worth reading.' Dennis Baldocchi, TRENDS in Ecology & Evolution '! pioneering, thought provoking and scholarly ! The bottom line is that, if you are interested in plant-atmosphere interactions, then this book is worth reading.' Dennis Baldocchi, TRENDS in Ecology and Evolution '! an excellent reference to a new approach using data on vegetation and the carbon cycle.' Philip E. LaMoreaux, Environmental Geology
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Zip Entry() always ends with / for any zip directory entry- To revert to the previous behavior, set the system property zip.ensure Trailing Slash to "false"- This change was made in order to fix a regression introduced in JDK 8u141 when verifying signed JARs that has caused some Web Start applications to fail to load- This release also contains fixes for security vulnerabilities described in the Oracle Java SE Critical Patch Update Advisory.
Creating a zip archive for a single file is very easy, we need to create a Zip Output Stream object from the File Output Stream object of destination file. Xml Zipping /Users/pankaj/tmp/Zipping /Users/pankaj/tmp/item. XML Zipping /Users/pankaj/tmp/Zipping /Users/pankaj/tmp/ms/Zipping /Users/pankaj/tmp/ms/Notice that while logging files to zip in directory, I am printing absolute path.
Zip Output Stream; public class App package com.mkyong.zip; import
" will be threw while extracting a zip file that contains a entry with size larger than Integer#MAX_VALUE bytes (about 2 GB).
Here is the java program showing how to zip a single file or zip a folder in java.package com.journaldev.files; import Then we add a new Zip Entry to the Zip Output Stream and use File Input Stream to read the source file to Zip Output Stream object. But while adding zip entry, I am using relative path from the directory so that when we unzip it, it will create the same directory structure. Once we are done writing, we need to close Zip Entry and release all the resources. If we find a file entry, we write the decompressed file. Oracle heeft voor de tweede keer in korte tijd een update voor versie 8 van zowel de developmentkit als de runtime-environment van Java Standard Edition uitgebracht. | <urn:uuid:aba11f3e-874b-4a55-ad83-8be8ff50a7f0> | 2.828125 | 419 | Documentation | Software Dev. | 49.796711 | 95,550,255 |
CENTERS FOR DISEASE CONTROL AND PREVENTIONA cell is not a soap bubble that can simply pinch in two to reproduce. The ability to faithfully copy genetic material and distribute it equally to daughter cells is fundamental to all forms of life. Even seemingly simple single-celled organisms must have the means to meticulously duplicate their DNA, carefully separate the newly copied genetic material, and delicately divide in two to ensure their offspring survive.
In eukaryotic cells such as those in plants and animals, an elaborate molecular circuitry coordinates duplication and separation of genetic material with division, much as the control knob on a washing machine coordinates agitation, rinsing and spinning. And the cellular control system, like the washing machine control system, has sensors that detect anomalies and shut things down if something is wrong.
What about bacteria? In the August 28 issue of Current Biology, Heidi A. Arjes, a doctoral student in the lab of Petra Levin, PhD, associate professor of biology in Arts & Sciences at Washington University in St. Louis, presents the first experimental data that show there are at least two fail-safe points in the bacterial cell cycle that tie DNA replication to cell division.
A cell that stumbles at either division or DNA replication can repair itself and re-enter the cell cycle. But if it does not do so quickly, the fail-safes are activated, forcing the cell to exit the cell cycle forever. It then enters a zombie-like state and is unable to reproduce even under the most favorable of conditions.
When nutrients are scarce, bacteria grow slowly, working through the cell cycle step-by-step. In nutrient rich conditions, however, bacteria take advantage of the situation to multiply as rapidly as possible, overlapping two of the steps: cell division and DNA replication—something that never happens in eukaryotic cells.
Because of their ability to overlap these two essential processes, bacteria have been thought to lack the fail-safe mechanisms that ensure stepwise progression through reproduction in eukaryotic cells.
Understanding the mechanisms of bacterial cell-cycle control may have major payoffs for medicine. Drugs that shut down the cell cycle could be used to fight bacterial infections. Not only would they prevent bacteria from multiplying, they would prevent them from passing on resistance genes or recovering once the drug had been metabolized.
Dividing at top speed
The bacterial cell cycle begins when a newborn daughter cell elongates and begins to make another copy of its DNA. As DNA replication proceeds, a division ring, called the Z-ring, starts to assemble at mid-cell. The Z-ring recruits other molecules to form a contractile ring and, once there are at least two complete copies of the DNA, pinches the bacterial cell in two to form daughter cells.
PETRA LEVINSo far the bacterial cell cycle isn’t all that different from the eukaryotic cell cycle. But when bacteria find themselves in nutrient-rich conditions, they shift into high gear, doubling in size and dividing as often as once every 20 minutes. Since it takes a bacterium 40 minutes to completely copy its DNA, how can it divide once every 20 minutes?
To make everything come out right, bacteria employ “multifork replication”: they initiate new rounds of DNA copying before the first round finishes. Getting a head start on DNA replication ensures at least one set of genetic material will be ready before they divide. Only the most mature DNA round must be complete before the cell divides. The other replication forks will finish in subsequent generations.
It was this overlap between replication and division that led to the traditional view that the bacterial cell cycle consists of parallel processes that are only loosely linked.
It was common sense that the processes had to be connected somehow, Levin said. After all, bacteria wait until one set of chromosomes is complete to divide. Dividing across incomplete or mingled DNA is usually lethal. “But until Heidi’s data, people spoke of the bacterial cell cycle as somehow magically coordinated even though there was no mechanism for doing so. Things just somehow worked out fine even though no control system had been identified.”
Blocking division blocks DNA replication
In the Current Biology article, Arjes and coworkers describe experiments that show cell division and DNA replication are not independent. New rounds of DNA replication depend on the successful completion of cell division and assembly of the division machinery at midcell depends on the initiation of DNA replication.
One set of experiments showed that after division is blocked, DNA replication gradually diminishes and, after about five generations, the bacterium reached the point of no return. In other experiments DNA replication was blocked directly. In this case, it took about three generations for the bacterium to reach the point of no return. The timing suggests DNA replication might be the event that shunts bacteria into the state of suspended animation.
What is the benefit of terminal arrest in a single-celled organism, whose main goal in life is to divide?
“It might actually be a form of altruism,” Arjes said. “In nature, bacteria often exist not in isolation, but in communities. An aged or unhealthy cell that removed itself from the population would benefit the community as a whole because it would no longer compete for nutrients or produce defective daughter cells.”
Although the research firmly establishes the existence of two fail-safe points in the bacterial cell cycle, the mechanisms that ensure proper cell-cycle progression are still a mystery.
“That’s the next thing we have to do,” Levin said. “Figure out how the division machinery is telling the DNA replication machinery something is wrong,” and how the “information that DNA replication isn’t working is communicated to the division machinery.”
These signaling pathways will be great targets for new antibiotic therapies. Drugs that drove bacteria past the point of no return would prevent them from proliferating, stalling an infection. Blocking DNA replication would prevent bacteria from sharing mutations that confer antibiotic resistance. “Most importantly,” says Arjes, “if a bacterium has encountered a terminal cell-cycle arrest, it cannot recover even after the drug has been metabolized.”
“People are already working on drugs that hit the division machinery,” said Arjes. “They’ve done a lot of screens; in fact in our experiments we used a new drug called PC190723 that blocks division in Staphyloccus aureus. It was synthesized for us by Jared Shaw, a chemist at the University of California at Davis, and is being tested against MRSA (methicillin-resistantStaphylococcus aureus) isolates.
“Combination therapy with PC190723 and other drugs such as methicillin, an extended-spectrum penicillin antibiotic, appear to be effective against MRSA even though methicillin alone is no longer effective. The division blocker somehow sensitizes the bacteria to drugs to which they have become resistant.”
The eukaryotic cell cycle has been studied for more than a century. Three scientists won the Nobel Prize for Physiology and Medicine in 2001 for figuring out the regulators that prevent the cell from dividing promiscuously and endlessly. It’s even possible to play a cell cycle control game at the Nobel site, Nobelprize.org.
“When I talk to people who study eukaryotic cells about our work with the bacterial cell cycle, they say, ‘What? This is new? People don’t know this?’” said Arjes. “But when I talk to people who study bacterial cells, they’re astonished. It’s a completely novel idea.”
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The ice goes on seemingly forever in a white pancake-flat landscape, stretching farther than ever before. And yet in this confounding region of the world, that spreading ice may be a cockeyed signal of man-made climate change, scientists say.This is Antarctica, the polar opposite of the Arctic.
While the North Pole has been losing sea ice over the years, the water nearest the South Pole has been gaining it. Antarctic sea ice hit a record 7.51 million square miles in September. That happened just days after reports of the biggest loss of Arctic sea ice on record.
Here we go again. What happened to the poles melting and flooding the land? What happened to the sun warming the planets or the fact the earth has gotten cooler?
I think these people flunked science in school. These people remind me of the 911ers who claimed to be experts. | <urn:uuid:7ab2efd5-7f7e-49a6-9d78-a0f6432547b9> | 2.703125 | 179 | Comment Section | Science & Tech. | 64.08146 | 95,550,262 |
Authors: Jeffrey Joseph Wolynski
Kelvin's Earth cooling timeframe makes sense only when a major assumption is exposed. Of course if Earth started as molten would only take 20-100 million years to cool to its given state, but the Earth did not start off as molten. Explanation is provided.
Comments: 2 Pages.
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By casting a silk thread into the wind spiders can ride the currents for distances ranging from a few metres to hundreds of miles, carrying them out of danger or into new territory. But scientists have puzzled over why 'spider ballooning' peaks during spring and autumn but declines in windy and sunny weather, when sunshine produces more updraughts helpful for take-off.
A research team at Rothamsted Research, a sponsored institute of the Biotechnology and Biological Sciences Research Council (BBSRC), has developed a model showing that light breezes and moderately warm weather - typically in spring and autumn - provides the best spider ballooning conditions.
The team of biologists and mathematicians found the best flight weather by calculating travelling distances under different conditions of wind and sun. Hot days will produce more updraughts but without sufficient wind the spiders are not able to drift anywhere. On the other hand, if the wind becomes too strong the updraughts are disrupted, making flight impossible.
Since spiders prey on pests like mites and aphids, predicting spider ballooning peaks is important for crop management, explains Dr Andy Reynolds at Rothamsted Research. "Each day of the growing season around 1800 spiders land in each hectare of arable farmland after ballooning. If the farmers can predict the influx of spiders, they can reduce the amount of pesticides accordingly," says Dr Reynolds.
The research team is planning field experiments to test the model, which could be relevant also for other organisms using the wind for transport, including mites and viruses.
Professor Julia Goodfellow, BBSRC Chief Executive, said: "This research is a good example of interdisciplinary collaboration, where biologists and mathematicians together have produced new knowledge which can help lead to environment-friendly pest control."
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O2 stable hydrogenases for applications
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The low-cost process, developed by Purdue University researchers, combines tools already used in industry for manufacturing metals on a large scale, but uses...
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Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
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Testing of Ligands
Molecular receptors, whose design and synthesis have been discussed in the preceding paper, are organic structures, held by covalent bonds, which are able to bind selectively substrates by the use of intermolecular interactions. These molecular interactions are of various origins: electrostatic interactions, hydrogen bonding, Van der Waals forces, etc.. The design of the receptor determines which substrate is to be bound, the energy and the specificity of complexation being governed by geometrical factors (topology of the ligand, size and shape of the internal cavity and of the substrate,. . .) and by the nature of the intermolecular interactions (electrostatic interactions for the binding of cations, presence of suitable donor binding sites for the complexation of transition metal cations, introduction of hydrogen bonds for the binding of anionic species, etc. . . .). The strength of the ligand-substrate interaction can be characterised by different physical constants. Thermodynamic (stability constants, enthalpy and entropy of formation of complexes), and kinetic parameters, are of prime importance in the definition of the properties of the ligand-substrate complex, for the understanding of the nature of the stabilising ligand-substrate interactions and in the design of new ligands.
KeywordsStability Constant Transition Metal Cation Metallic Cation Molecular Cavity Good Receptor
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- (1).Metz,B., Moras, D., and Weiss, R: 1971, Chem. Comm.,p.- 444 and references cited therein.Google Scholar
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Silver Nanoparticles Take Spectroscopy to New Dimension
News Jan 03, 2018 | Original Story from the American Institute of Physics.
Detection of a low concentration analyte molecule using silicon nanowires decorated with silver nanoparticles and surface enhanced Raman scattering measurements. Credit: V.S. Vendamani.
As medicine and pharmacology investigate nanoscale processes, it has become increasingly important to identify and characterize different molecules. Raman spectroscopy, a technique that leverages the scattering of laser light to identify molecules, has a limited capacity to detect molecules in diluted samples because of low signal yield.
A team of researchers from the University of Hyderabad in India has improved molecular detection at low concentration levels by arranging nanoparticles on nanowires to enhance Raman spectroscopy. Surface-enhanced Raman spectroscopy (SERS) uses electromagnetic fields to improve Raman scattering and boost sensitivity in standard dyes such as R6G by more than one billionfold.
The team decorated vertically aligned silicon nanowires with varying densities of silver nanoparticles, utilizing and enhancing the structure's 3-D shape. Their results, published in the Journal of Applied Physics, from AIP Publishing, show that their device was able to enhance the Raman signals for cytosine protein and ammonium perchlorate by a factor of 100,000.
“The beauty is that we can improve the density of these nanowires using simple chemistry,” said Soma Venugopal Rao, one of the paper’s authors. “If you have a large density of nanowires, you can put more silver nanoparticles into the substrate and can increase the sensitivity of the substrate.”
Applying the necessary nanostructures to SERS devices remains a challenge for the field. Building these structures in three dimensions with silicon nanowires has garnered attention for their higher surface area and superior performance, but silicon nanowires are still expensive to produce.
Instead, the team was able to find a cheaper way to make silicon nanowires and used a technique called electroless etching to make a wide range of nanowires. They “decorated” these wires with silver nanoparticles with variable and controlled densities, which increased the nanowires’ surface area.
“Optimizing these vertically aligned structures took a lot of time in the beginning,” said Nageswara Rao, another of the paper’s authors. “We increased the surface area and to do this we needed to change the aspect ratio.”
After optimizing their system to detect Rhodamine dye on a nanomolar level, these new substrates the team built enhanced Raman sensitivity by a factor of 10,000 to 100,000. The substrates detected concentrations of cytosine, a nucleotide found in DNA, and ammonium perchlorate, a molecule with potential for detecting explosives, in as dilute concentrations as 50 and 10 micromolar, respectively.
The results have given the team reason to believe that it might soon be possible to detect compounds in concentrations on the scale of nanomolar or even picomolar, Nageswara Rao said. The team’s work has opened several avenues for future research, from experimenting with different nanoparticles such as gold, increasing the sharpness of the nanowires or testing these devices across several types of molecules.
This article has been republished from materials provided by the American Institute of Physics. Note: material may have been edited for length and content. For further information, please contact the cited source.
V. S. Vendamani, S. V. S. Nageswara Rao, S. Venugopal Rao, D. Kanjilal, A. P. Pathak. Three-dimensional hybrid silicon nanostructures for surface enhanced Raman spectroscopy based molecular detection. Journal of Applied Physics, 2018; 123 (1): 014301 DOI: 10.1063/1.5000994.
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Approximately 359 million light-years away from Earth, there is a galaxy with an innocuous name (PGC 1000714) that doesn't look quite like anything astronomers have observed before. New research provides a first description of a well-defined elliptical-like core surrounded by two circular rings -- a galaxy that appears to belong to a class of rarely observed, Hoag-type galaxies. This work was done by scientists at the University of Minnesota Duluth and the North Carolina Museum of Natural Sciences. (You can see video about this research at https:/
"Less than 0.1% of all observed galaxies are Hoag-type galaxies," says Burcin Mutlu-Pakdil, lead author of a paper on this work and a graduate student at the Minnesota Institute for Astrophysics, University of Minnesota Twin Cities and University of Minnesota Duluth.
Hoag-type galaxies are round cores surrounded by a circular ring, with nothing visibly connecting them. The majority of observed galaxies are disc-shaped like our own Milky Way. Galaxies with unusual appearances give astronomers unique insights into how galaxies are formed and change.
The researchers collected multi-waveband images of the galaxy, which is only easily observable in the Southern Hemisphere, using a large diameter telescope in the Chilean mountains. These images were used to determine the ages of the two main features of the galaxy, the outer ring and the central body.
While the researchers found a blue and young (0.13 billion years) outer ring, surrounding a red and older (5.5 billion years) central core, they were surprised to uncover evidence for second inner ring around the central body. To document this second ring, researchers took their images and subtracted out a model of the core. This allowed them to observe and measure the obscured, second inner ring structure.
"We've observed galaxies with a blue ring around a central red body before, the most well-known of these is Hoag's object. However, the unique feature of this galaxy is what appears to be an older diffuse red inner ring," says Patrick Treuthardt, co-author of the study and an astrophysicist at the North Carolina Museum of Natural Sciences.
Galaxy rings are regions where stars have formed from colliding gas. "The different colors of the inner and outer ring suggest that this galaxy has experienced two different formation periods," Mutlu-Pakdil says. "From these initial single snapshots in time, it's impossible to know how the rings of this particular galaxy were formed." The researchers say that by accumulating snapshot views of other galaxies like this one astronomers can begin to understand how unusual galaxies are formed and evolve.
While galaxy shapes can be the product of internal or external environmental interactions, the authors speculate that the outer ring may be the result of this galaxy incorporating portions of a once nearby gas-rich dwarf galaxy. They also say that inferring the history of the older inner ring would require the collection of higher-resolution infrared data.
"Whenever we find a unique or strange object to study, it challenges our current theories and assumptions about how the Universe works. It usually tells us that we still have a lot to learn," says Treuthardt.
An uncorrected proof of the peer-reviewed paper, "A photometric study of the peculiar and potentially double ringed, nonbarred galaxy: PGC 1000714," was published online in the Monthly Notices of the Royal Astronomical Society by Oxford University Press on Nov. 30, 2016 and will appear online at http://doi.
Note to Editors: The study abstract follows.
"A photometric study of the peculiar and potentially double ringed, nonbarred galaxy: PGC 1000714"
Authors: Burcin Mutlu Pakdil, University of Minnesota Duluth and University of Minnesota Twin Cities; Mithila Mangedarage, University of Minnesota Duluth; Marc S. Seigar, University of Minnesota Duluth; Patrick Treuthardt, North Carolina Museum of Natural Sciences
Published: Nov. 30, Monthly Notices of the Royal Astronomical Society
Abstract: We present a photometric study of PGC 1000714, a galaxy resembling Hoag's Object with a complete detached outer ring, that has not yet been described in the literature. Since the Hoag-type galaxies are extremely rare and peculiar systems, it is necessary to increase the sample of known objects by performing the detailed studies on the possible candidates to derive conclusions about their nature, evolution, and systematic properties. We therefore performed surface photometry of the central body by using the archival near-UV, infrared data and the new optical data (BVRI). This current work has revealed for the first time an elliptical galaxy with two fairly round rings. The central body follows well a r1/4 light profile, with no sign of a bar or stellar disc. By reconstructing the observed spectral energy distribution (SED), we recover the stellar population properties of the central body and the outer ring. Our work suggests different formation histories for the galaxy components. Possible origins of the galaxy are discussed, and we conclude that a recent accretion event is the most plausible scenario that accounts for the observational characteristic of PGC 1000714.
Burcin Mutlu-Pakdil | EurekAlert!
What happens when we heat the atomic lattice of a magnet all of a sudden?
18.07.2018 | Forschungsverbund Berlin
Subaru Telescope helps pinpoint origin of ultra-high energy neutrino
16.07.2018 | National Institutes of Natural Sciences
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
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A Game of Commuting Matrices
April 22, 2013
Bailey Hall 207
Refreshments will be served in Bailey Hall 204 at 4:15
One of the first things that we learn about multiplication of matrices is that it is not "commutative", that is if A and B are two square matrices of the same size then in general A.B is not the same as B.A. However, we can easily think of pair of matrices that do "commute", e.g. if one of the matrices is the identity matrix or the zero matrix, or if A and B are both the same, then we will have A.B=B.A. So it is natural to ask: which pairs of matrices do in fact commute? The goal of this talk is to present a refined version of this natural question, using one of the most important classical theorems in linear algebra, the Jordan Decomposition Theorem. We are going to introduce a game which will help us understand the main idea of Jordan decomposition theorem, as well as the question of commuting pairs of matrices.
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Presentation on theme: "University of Colorado and NOAA/Climate Diagnostics Center"— Presentation transcript:
1 University of Colorado and NOAA/Climate Diagnostics Center Mainstreaming Adaptation to Climate Change (MACC) Issue Paper (DRAFT) Climate Change in the Caribbean: Water, Agriculture, ForestryDr. Roger S. PulwartyUniversity of Colorado andNOAA/Climate Diagnostics CenterBoulder CO 80305
2 Timescales of Climate Variation And Climate Change in the Caribbean BackgroundWater Resources in the Caribbean: an overviewAgriculture, Food Security and Forestry in the CaribbeanTimescales of Climate Variation And Climate Change in the CaribbeanImpacts on Water ResourcesImpacts on Agriculture and Food SecurityApproaches to Adaptation: Integrating climate andnatural resources assessments under a decision-oriented framework
3 AppendicesAPPENDIX B. Climate and APPENDIX A: Water and Climate Dialogue Summary StatementsFood Security: Implications for Research and PolicyAPPENDIX C. IWCAM Summary statementsAPPENDIX D. Climate and agricultural applications in the Caribbean: A case study of climate information use in sugar production in Trinidad (summary)
4 Three questions under the MACC framework: Are planning strategies for water, agricultural and forest resources in the Caribbean supported by the climate record?What additional pressures will be placed on these resources as a result of projected climatic variability and change?(3) What practical strategies may be engaged to reduce vulnerability and enhance social, economic and ecological resilience?
5 Characteristics of small island environments Ecological/environmentalGeographicalSocio-economicHistorical and political
6 Climate change projections for the Caribbean region TrendsAvg. annual air temp 1 FSea level rise 10 cm (3.9 ins) per 100 yrsGenerally drier conditionsScenarios for Future Climate2-3 CDrier mid-year, wetter end of yearOcean surface warmingSalt water intrusion into freshwaterSome models suggest more persistent ENSO-like conditions and less but more intense more intense tropical storms (5-10% windspeed)
8 Changes in the total amount of precipitation and in its frequency and intensity directly affect the magnitude and timing of runoff and theintensity of floods and droughts; however, at present, specificregional effects are uncertainThe impacts of climate change will depend on the baseline conditionsof the water supply system and the ability of water resourcemanagers to respond not only to climate change but also topopulation growth and changes in demands, technology, andeconomic, social and legislative conditionsNote: the latter are also “baseline” conditions
9 Where does climate variability come from?NAOTAENSO
19 Non-ENSO or Atlantic multi-decadal mode of global sea surface temperature(SST) (A) spatial correlations between first EOF and Atlantic SSTs; (B) temporal reconstruction of variability averaged over the rectangle in A (Goldenberg et all 2001)
20 Caribbean hurricane tracks and strength during (A) warm and (B) cold Atlantic multidecadal modes
21 The question remains “ Can we produce reliable baselines for planning give the large amount of year to year and decade to decade variations in the Caribbean?”Need for careful monitoring and inventory of critical variables and indicators (available and gaps)Need for “upscaling” local climate/met./hydro data and experience as well as “downscaling” models (precision vs. accuracy)
22 …viewed from Sectors and more… The Decision Mineral & Fossil Fuel AssessmentInformation and Decision Support SystemsKnowledge-based ProductsClimate SimulationsObservations and MonitoringThe DecisionInterdisciplinary ResearchMineral &Fossil FuelExtractionAgriculture& silvicultureUrbanDevelopmentWater &SustainabilityEcosystem &Land UseManagementConservation& BiodiversityHealth &Diseaseand more…Recreation
23 Integrated Water Resource Assessments Assessment of biophysical impacts on:hydrologic resources,water quality, andaquatic ecosystem integrity.Assessment of socio-economic impacts on:demand from market water use sectors, andwater resources management systems
24 Water resources adaptations Supply adaptation:modification of existing physical infrastructure;construction of new infrastructure; andalternative management of the existing water supply systemsDemand adaptation:conservation and improved efficiency;technological change; andmarket/price-driven transfers to other activities.
27 Trends and conditioning factors Unit(s) of analysis: Upstream-downstream,watershed, urbanRelevant hydro-climatic variables: data,qc, uncertaintiesDemands : Scale, trends and criticalityReliability of supply and distributionSeparation of regulatory and operational responsibilitiesIntegration of water quantity and qualitySecurity of rightsIncorporation of climate issues in existing networks priorities and policiesPost-audits of past events and technical interventions- if we did or are doing everything possible why did it work or not work?
28 Established frameworks for water allocation: national level Legal basis- water rights, legal/regulatory frameworkInstitutional base-Govt. and Non-govt. Mandates,responsibilities and practicesTechnical base-monitoring, assessment, decision support modelingFinancial and economic aspects-costs/benefits,pricing tradingParticipationStructural and development base-water supply and operations, users
30 Optimizing the net social benefit Difficulty in dealing with all related social aims of water/natural resource usesDifficulty in forging agreed-upon criteria for program evaluationLack of progress in comprehensive integrated management and in coordinating watersheds plansLack of comprehensive assessments of projects and initiatives
31 “Sufficient, reliable data are not available or shared at present to undertake a thorough analysis of the multiple threats to water resources, forestry, or food security”e.g. water consumption rates (availability per capita) and access to network water and sanitation facilities: changing levels of domestic water use, deterioration? Of piped water, tourism, costs of obtaining water
32 IWCAM…Institutional mechanisms must be put in place at the national and regional level, to undertake the regular dissemination of user-friendly information on such technologies as well as to assist with the training of nationals in the use of such technologyIntroduction of incentives to encourage the use of appropriateWhat does “capacity building” mean in this context?
33 ….viewed from Information chain Dialog, not two monologuesAssessmentInformation and Decision Support SystemsKnowledge-based ProductsClimate SimulationsObservations and MonitoringThe DecisionInterdisciplinary ResearchImprovedDecisionProcessInformation and Decision Support SystemsKnowledge-based ProductsClimate SimulationsThe DecisionInterdisciplinary ResearchObservations and MonitoringDistributed disseminationNew technologiesInteractiveUser friendlyFlexibleKnowledge-based ProductsThe DecisionInterdisciplinary ResearchObservations and MonitoringClimate SimulationsPlace-based and sector-basedUser orientedScenarios and probabilistic outcomesSynthesisClimate SimulationsThe DecisionInterdisciplinary ResearchObservations and MonitoringTypes of modelsScaleTemporalSpatialPerformance metricsObservations and MonitoringThe DecisionInterdisciplinary ResearchNetwork designPlatformsAppropriate mix of observationsQuality assurance and controlThe DecisionInterdisciplinary ResearchFraming the questionSynthesis toolsData assimilation & visualizationComplexity modelsScenario development and testingUnderstanding methodologiesPlace-basedThe DecisionClimate simulations & scenariosSocial trendsDemographicsEnergy useLand useInstitutionsPoliciesLawsValuesPolitics
34 Create a matrix of functional responsibilities of water-related Ministries and organizations to identify pathways for decision-making1. Establishing and consolidate a viable scientific basis for water resources management sector and for (inter)national (water) policiesInitiating a multi-stakeholder process that builds the knowledge to cope with climate variability and change.Building and share knowledge and information by bridging climate variability/change and water communities4. Raising awareness of the issues relating climate and water, and broaden scientific, political and water managers participation in the discussion
36 Understand Current Vulnerability and Assess Trends Effects Related to Altered ResourcesCharacterize the Risk of Climatic Variations and Review Past and Potential ResponsesNational Food BalanceInstitutional DevelopmentHousehold Food PovertyIncome ComponentsCultural PreferencesDemographyIndividual Food DeprivationNutritional StatusHealth StatusSocial Status: Three pillars of food security: food production, economic access to available food, and nutritional securityWhich group(s) really maintain these pillars?
37 Developing effective decision environments (a role for C5) Establish Regional Climate and Natural Resources Roundtables (which also provide for data sharing)Serve as a clearinghouse mechanism for promoting, initiating and facilitating climate change programs and policies;Review national strategies for enhancing the objectives of the UN Framework Convention on Climate Change and advising government on the way forwardSuch Roundtables should:Evaluate options, information, and technology and to examine the sectors that will most benefit from these inputs among existing institutionsExplore the feasibility of establishing a regional plan of action to identify and adapt, where appropriate, successful examples of water conservation and watershed programs;Identify entry points for information at different levels of governance(not just information provision)
38 IndeterminateClimate and cross-scale watershed issues: Linear vs. Adaptive managementLong-termDecadeYearSeasonalMonthlyDailyHourlyHousehold-municipal-NationalGlobalParish/CountyRegional
39 Developing prototypes or pilot studies for climate impacts assessments Select the exposure unit (usually at the watershed)Define the study area and critical issueDetermine general data availability and adequacySelect a time horizonIdentify trends and influences on trend for critical issuesIdentify a preliminary range of adaptationsDetermine the need for integration across sectorsProblem-orientationDo we really know how we adjust to drought condtions?
42 Approaches to risk communication and associated assumptions ___________________________________________________________________________Approach Assumptions and actionsDevelopment and From the risk expert to the public--finite anddelivery of a risk message uni-directionalAimed at bringing public views into line with expert viewsAssumes expert view has more validity for decision- makingDialogue about risk Interactive exchange of risk information--continuousAimed at balancing the content of risk messageAssumes both views contribute to decision-makingSocial processes Engage in a process that addresses concerns about riskof risk communication Aimed at enhancing understanding among stakeholders (DECISIVE AND NON-DECISIVE). Assumes the process is as important as the product_____________________________________________________________________________i.e. more than a one-way or even two-way street
43 Not simply communicating after project is over Link pilots to strong institutional mechanisms: Realizing implementationPast recommendations and interventions: How effective were they? What criteria are used for evaluation?Not simply communicating after project is overInvolving local organizations in planning andimplementationPartnerships (not just stakeholder assessments)How is the common interest pursued and secured? Where and why have particular local organizations been successful and sustained?
44 Mainstreaming……..What partnerships need to be engaged? What activities already exist?Goals of participants: What is being valued?(by “experts and role of experts”, state agencies, NGOs, local communities) Whose agenda are we agreeing on?Trends: Robustness: choice, inventory and baselinesConditioning factors: reconstructing influences on events, past interventionsProjections (scenarios and uncertainties)Alternatives: acting under uncertain informationPathways to decision-making: ,data, methods,Entry points: salience, legitimacy, acceptability, context
45 How does innovation occur How does innovation occur? Rate of adoption of knowledge-based innovation in water resources agencies Y= f(Xi)Xi = (compatibility of innovation with needs and values.capacity and characteristics.1/complexity of innovation.communicability within agency.communication networks outside(incl. other resources and othernational water agencies).% of initial innovators.investment in innovation
46 Rate of adoption of knowledge-based innovation Y= f(Xi) .observability in practice:who is else is involved?.evaluation of support tools:DSS,pricing (transfer of tested and untested approaches).respect conferred) | <urn:uuid:b83da020-8af3-4769-a73a-45dac326fd33> | 2.640625 | 2,505 | Audio Transcript | Science & Tech. | -30.776026 | 95,550,389 |
from Ada and Euclid to Quantum Computing and the World Wide Web
|Schedule - Problem Sets - Exams - Lectures - Syllabus - Links|
Schemer's Guide to Structured Query Language
Structured Query Language, or SQL, is a language used to manipulate and extract the information in a database. Data is stored in tables. Tables are structured by rows and fields (columns). Fields are general categories of information, while rows represent related information. SQL is used to manage the tables in a database through queries.
Creating a DatabaseBefore you can start, you need to create a database account on the UVa Server. ITC (Office of Information, Technology and Communication) provides free access to a MySQL database to all UVa students.
- Open https://dbm1.itc.virginia.edu in a web browser
- Click "Get/Reset an Account"
- Enter the information required. For security reasons, you should not use a password you use for anything important. Since you need to use the database password in plaintext in your PHP files to access the database, it is not secure.
- You'll get a confirmation page if everything went according to plan.
- Go to https://dbm1.itc.virginia.edu/phpMyAdmin/index.php3
- A little box pops up asking for your username and the password you just entered.
- Create a new database for all your CS 200 needs. Call it abc1x_cs200, where abc1x is your username, of course. Hit the "create" button to do this.
- Now, on the left, click on abc1x_cs200. You are now in the database administration page, where you can run SQL commands (described below) to manipulate your database.
The basic SQL commands are described by the following grammar:
Commands ::= Command ; CommandsSQL commands are case-insensitive (create means the same thing as CREATE). By convention, we will use all capitals to distinguish SQL commands. The non-terminals use in these productions will be described later. This document describes the most important SQL commands; for full details see http://www.mysql.org/doc/.
Commands ::= Command
Command ::= CreateTableCommand | InsertCommand | SelectCommand | UpdateCommand | DeleteCommand | DropTableCommand
CreateTable ::= CREATE TABLE Name (FieldDefinitions)
InsertCommand ::= INSERT INTO Table ( FieldNames ) VALUES (Values)
DeleteCommand ::= DELETE FROM Table WhereClause
SelectCommand ::= SELECT Fields FROM Table JoinClause WhereClause OrderClause
UpdateCommand ::= UPDATE Table SET SetList WhereClause
DropTable ::= DROP TABLE Table
Creating a Table
You create a table with the CREATE TABLE command (MySQL Documentation):CreateTable ::= CREATE TABLE Name (FieldDefinitions)
FieldDefininitions::= FieldDefintion, FieldDefinitions
FieldDefinitions ::= FieldDefinition
FieldDefinition ::= FieldName FieldType PrimaryModifier NullModifier IncrementModifier
PrimaryModifier ::= PRIMARY KEY
NullModifier ::= NOT NULL | NULL
OptIncrement ::= AUTO_INCREMENT
FieldType ::= DATE | TIME | DATETIME | INT | FLOAT | VARCHAR (Number) | TEXT
FieldName ::= Name
FieldName ::= Table.Name
Table ::= name of a table
You can create as many tables in your database as you want. Each table has any number of rows, but must have at least one field (note that CreateDefinitions cannot be replaced with the empty string, there must always be at least on definition).
In addition, at least one of the fields must be a primary key. A primary key is used to uniquely identify rows in the table. The easiest example usually concerns names. Let's say you had a table of your friends. You may have two friends named "John Smith". How would you tell them apart in your table? You need another field, in addition to name, that assigns them something unique. It could be their e-mail address, or their social security number. For our puposes, however, let's just use integers that counts starting from 1. Here's how:
CREATE TABLE CSBooks ( BookID INT PRIMARY KEY NOT NULL AUTO_INCREMENT, Title VARCHAR (30), Author VARCHAR (30), Price FLOAT, Publisher VARCHAR (30), Year INT );
Try this yourself by pasting this code in the Run SQL query ... form you get from https://dbm1.itc.virginia.edu/phpMyAdmin/index.php3 (after creating an account and database as described above) and clicking the Go button.
Inserting RowsNow that we have created a table, we can put data in our table using the insert command: (MySQL Documentation)InsertCommand ::= INSERT INTO Table ( FieldNames ) VALUES (Values)To put a new field into our CSBooks table we could use the following insert command:
Values ::= Value Values
Values ::= Value ::= Number | String | Date | Boolean
FieldNames ::= FieldName , FieldNames
FieldNames ::= FieldName
INSERT INTO CSBooks (Title, Author, Price, Publisher, Year)
VALUES ('The Mind''s I', 'Hofstadter', 18.95, 'Bantam', 1985)
Try evaluating this yourself by pasting this code in the Run SQL query ... form you get from https://dbm1.itc.virginia.edu/phpMyAdmin/index.php3. Click on Browse to see the table.
Two idiosyncrasies to note. Firstly, notice that we enclose a string with single quotes ('). Numbers and dates are not enclosed. However, one of the fields (Title) has a single quote in the text. If we wrote 'The Mind's I' , then SQL would think the book is called "The Mind" and that "s I" was some sort of SQL command. Instead, we need to use '' to make the single quote. SQL treats two consecutive single quotes differently as a single quote in the quoted string.
Secondly, note that we do not tell SQL what to insert in the BookID field. This is because when we created the table we used AUTO_INCREMENT to indicate that the BookID field should automatically increment when we insert new entries in our table. This means that the database will automatically assign the next available integer (in this case, 7) to be the key for this row.
The table now looks like this:
BookID Title Author Price Pubisher Year 1 The Mind's I Hofstadter 18.95 Bantam 1985
We can insert a few more entries into our table the same way:After this, our table is:INSERT INTO CSBooks (Title, Author, Price, Publisher, Year) VALUES ('GEB', 'Hofstadter', 19.95, 'Basic', 1979);
INSERT INTO CSBooks (Title, Author, Price, Publisher, Year) VALUES ('Cryptonomicon', 'Stephenson', 14.25, 'Perennial', 1999);
INSERT INTO CSBooks (Title, Author, Price, Publisher, Year) VALUES ('The Code Book', 'Singh', 14.00, 'Anchor', 2000);
INSERT INTO CSBooks (Title, Author, Price, Publisher, Year) VALUES ('Snow Crash', 'Stephenson', 13.75, 'Bantam', 1992);
INSERT INTO CSBooks (Title, Author, Price, Publisher, Year) VALUES ('Fermat''s Enigma', 'Singh', 11.85, 'Anchor', 1997);
BookID Title Author Price Publisher Year 1 The Mind's I Hofstadter 18.95 Bantam 1985 2 GEB Hofstadter 19.95 Basic 1979 3 Cryptonomicon Stephenson 14.25 Perennial 1999 4 The Code Book Singh 14.00 Anchor 2000 5 Snow Crash Stephenson 13.75 Bantam 1992 6 Fermat's Enigma Singh 11.85 Anchor 1997
The delete command removes entries from a table: (MySQL Documentation)DeleteCommand ::= DELETE FROM Table WhereClauseThe where clause of a delete command specifies which rows to delete using boolean conditions. All rows for which the Conditions specified in the where clause are true are permanently removed from the table. For example, to remove all books published by Anchor that cost more than $12.00, we could use the following query:
WhereClause ::= WHERE Conditions
Conditions ::= Condition Conjunction Conditions
Conditions ::= Condition
Conjunction ::= AND | OR
Condition ::= Field Comparator Value
Comparator ::= < | > | = | <= | >=
DELETE FROM CSBooks WHERE Publisher='Anchor' AND Price > 12.00
This removes the entry for The Code Book from our table. If no conditions are specified in the delete command every entry will be deleted, so be careful! If you only want to delete one entry, the safest bet is to tell it to delete based on the primary key. For example, to delete The Mind's I do:After this, our table is:
DELETE FROM CSBooks WHERE BookID=1
BookID Title Author Price Publisher Year 2 GEB Hofstadter 19.95 Basic 1979 3 Cryptonomicon Stephenson 14.25 Perennial 1999 5 Snow Crash Stephenson 13.75 Bantam 1992 6 Fermat's Enigma Singh 11.85 Anchor 1997
The select command is used to extract a table from a table: (MySQL Documentation)SelectCommand ::= SELECT FieldSpecifier FROM Table JoinClause WhereClause OrderClauseA select command evaluates to a new table containing the selected entries. For example, if we wanted to get all the titles and their authors from our CSBooks table we could use the following query:
FieldSpecifier ::= Fields Fields ::= Field, Fields
Fields ::= FieldModifier Field
Fields ::= *
Field ::= name of a field in the table AS Name
Field ::= name of a field in the table
FieldSpecifier ::= Operator ( Fields ) AS Name
Operator ::= AVG | COUNT | MIN | MAX | SUM
FieldModifier ::= DISTINCT
JoinClause ::= INNER JOIN Table ON expandedField = expandedField
OrderClause ::= ORDER BY Field Descending
Descending ::= DESC
SELECT Title, Author
The result would be a table that looks like this:
Title Author GEB Hofstadter Cryptonomicon Stephenson Snow Crash Stephenson Fermat's Enigma Singh
To select all of the fields, the asterix (*) can be used instead of listing field names.
We can add a where clause to our query to make it more specific. Where clauses are the same as was introduced for the delete command. For example, we could use the following query to find all the books by Stephenson that are less then $15:
SELECT * FROM CSBooks
WHERE Author='Stephenson' AND Price < 14.00
This would result in the table:
BookID Title Author Price Publisher Year 5 Snow Crash Stephenson 13.75 Bantam 1992
We can also use SELECT queries to do simple calculations on our results. To find the total price of all books published before 1990 we could use the following query:
SELECT SUM(Price) AS Total FROM CSBooks WHERE Year < 1995
When performing calculations, you are, in essence, creating a new field. Therefore you must give it a name using AS. The result of this query would be:
Other calculations available include AVG to find an average of a set of numbers, COUNT to find out how many rows of results there are, MIN to find the minimum value, and MAX to find the maximum. The following query will count how many books Anchor has published:
SELECT COUNT(*) FROM CSBooks WHERE Publisher="Anchor"
We may want a list of the authors in our table. For this situation we would not want duplicate names. This can be accomplished using the DISTINCT keyword in the following manner:
SELECT DISTINCT Author
This will automatically filter all duplicates from the results and will produce the table
Author Hofstadter Singh Stephenson
SQL can also specify that the results should be sorted by a particular field by adding an order clause at the end of the select statement. To get a list of the books sorted by date we could use the query
SELECT * FROM CSBooks ORDER BY Year
which will result in the table
BookID Title Author Price Pubisher Year 2 GEB Hofstadter 19.95 Basic 1979 5 Snow Crash Stephenson 13.75 Bantam 1992 6 Fermat's Enigma Singh 11.85 Anchor 1997 3 Cryptonomicon Stephenson 14.25 Perennial 1999
To sort the list in the reverse order, add the keyword DESC to the end of the query.
There is one option in a select command, called a join, that is useful when dealing with multiple tables. A join combines two tables by a common field. Suppose we have the following table named Orders, of people who have ordered books. Note that we reference the books by BookID since that is the primary key of the CSBooks table.
BookID Name 2 Ada 5 Gödel 3 Bach 6 Bach
To get a full list of orders we could use the following query:
SELECT Name, Title, Author, Price, Publisher, Year
Orders INNER JOIN CSBooks
ON Orders.BookID = CSBooks.BookID
The resulting table looks like this:
Name Title Author Price Publisher Year Ada GEB Hofstadter 19.95 Basic 1979 Gödel Snow Crash Stephenson 13.75 Bantam 1992 Bach Cryptonomicon Stephenson 14.25 Perennial 1999 Bach Fermat's Enigma Singh 11.85 Anchor 1997
The join is a very powerful mechanism. By combining joins with order and where clauses you can express compilcate queries on databases.
There are many different ways to express the same join. Just so you're not confused by other people's code, the following three SQL statements are precisely identical to each other:Select can do much more than what is described here, see the MySQL Documentation if you need to do a more complicated selection.
SELECT Name, Title, Author, Price, Publisher, Year FROM CSBooks
JOIN Orders WHERE CSBooks.Publisher = 'Anchor' AND CSBooks.BookID = Orders.BookID
SELECT Name, Title, Author, Price, Publisher, Year FROM CSBooks, Orders
WHERE CSBooks.Publisher = 'Anchor' AND CSBooks.BookID = Orders.BookID
SELECT Name, Title, Author, Price, Publisher, Year FROM Orders
INNER JOIN CSBooks USING (Title) WHERE CSBooks.Publisher = 'Anchor'
An update command can be used to change information already in the table. Update has a similar syntax to the other queries with some extra information to specify the information to change using the SET keyword:UpdateCommand ::= UPDATE Table SET SetList WhereClauseFor example, the following query will change all of Stephenson's publishers to Doubleday and raise the price to 49.95.
SetList ::= Set, SetList
Set ::= Field = Value
UPDATE CSBooks SET Publisher='Doubleday', Price=49.95 WHERE Author='Stephenson'
Like the delete command, if no conditions are specified all of the rows will be set with the given information. Also like the DELETE query, you'll also want to reference the primary key to ensure that you're operating on the rows that you think you are.
The drop table command permanently removes an entire table from the database:DropTable ::= DROP TABLE TableBe careful! You lose everything in the table after a drop command.
Credits: This guide was created by Jon Erdman, Portman Wills and David Evans.
Using these Materials | <urn:uuid:9502b2c5-21fd-4ba3-817d-e535360cfc50> | 3.8125 | 3,394 | Documentation | Software Dev. | 50.761092 | 95,550,399 |
Water cycle(Redirected from Hydrologic cycle)
The water cycle, also known as the hydrological cycle or the hydrologic cycle, describes the continuous movement of water on, above and below the surface of the Earth. The mass of water on Earth remains fairly constant over time but the partitioning of the water into the major reservoirs of ice, fresh water, saline water and atmospheric water is variable depending on a wide range of climatic variables. The water moves from one reservoir to another, such as from river to ocean, or from the ocean to the atmosphere, by the physical processes of evaporation, condensation, precipitation, infiltration, surface runoff, and subsurface flow. In doing so, the water goes through different forms: liquid, solid (ice) and vapor.
The water cycle involves the exchange of energy, which leads to temperature changes. When water evaporates, it takes up energy from its surroundings and cools the environment. When it condenses, it releases energy and warms the environment. These heat exchanges influence climate.
The evaporative phase of the cycle purifies water which then replenishes the land with freshwater. The flow of liquid water and ice transports minerals across the globe. It is also involved in reshaping the geological features of the Earth, through processes including erosion and sedimentation. The water cycle is also essential for the maintenance of most life and ecosystems on the planet.
The sun, which drives the water cycle, heats water in oceans and seas. Water evaporates as water vapor into the air. Some ice and snow sublimates directly into water vapor. Evapotranspiration is water transpired from plants and evaporated from the soil. The water molecule H
2O has smaller molecular mass than the major components of the atmosphere, nitrogen and oxygen, N
2 and O
2, hence is less dense. Due to the significant difference in density, buoyancy drives humid air higher. As altitude increases, air pressure decreases and the temperature drops (see Gas laws). The lower temperature causes water vapor to condense into tiny liquid water droplets which are heavier than the air, and fall unless supported by an updraft. A huge concentration of these droplets over a large space up in the atmosphere become visible as cloud. Some condensation is near ground level, and called fog.
Atmospheric circulation moves water vapor around the globe, cloud particles collide, grow, and fall out of the upper atmospheric layers as precipitation. Some precipitation falls as snow or hail, sleet, and can accumulate as ice caps and glaciers, which can store frozen water for thousands of years. Most water falls back into the oceans or onto land as rain, where the water flows over the ground as surface runoff. A portion of runoff enters rivers in valleys in the landscape, with streamflow moving water towards the oceans. Runoff and water emerging from the ground (groundwater) may be stored as freshwater in lakes. Not all runoff flows into rivers, much of it soaks into the ground as infiltration. Some water infiltrates deep into the ground and replenishes aquifers, which can store freshwater for long periods of time. Some infiltration stays close to the land surface and can seep back into surface-water bodies (and the ocean) as groundwater discharge. Some groundwater finds openings in the land surface and comes out as freshwater springs. In river valleys and floodplains, there is often continuous water exchange between surface water and ground water in the hyporheic zone. Over time, the water returns to the ocean, to continue the water cycle.
- Condensed water vapor that falls to the Earth's surface. Most precipitation occurs as rain, but also includes snow, hail, fog drip, graupel, and sleet. Approximately 505,000 km3 (121,000 cu mi) of water falls as precipitation each year, 398,000 km3 (95,000 cu mi) of it over the oceans.[better source needed] The rain on land contains 107,000 km3 (26,000 cu mi) of water per year and a snowing only 1,000 km3 (240 cu mi). 78% of global precipitation occurs over the ocean.
- Canopy interception
- The precipitation that is intercepted by plant foliage eventually evaporates back to the atmosphere rather than falling to the ground.
- The runoff produced by melting snow.
- The variety of ways by which water moves across the land. This includes both surface runoff and channel runoff. As it flows, the water may seep into the ground, evaporate into the air, become stored in lakes or reservoirs, or be extracted for agricultural or other human uses.
- The flow of water from the ground surface into the ground. Once infiltrated, the water becomes soil moisture or groundwater. A recent global study using water stable isotopes, however, shows that not all soil moisture is equally available for groundwater recharge or for plant transpiration.
- Subsurface flow
- The flow of water underground, in the vadose zone and aquifers. Subsurface water may return to the surface (e.g. as a spring or by being pumped) or eventually seep into the oceans. Water returns to the land surface at lower elevation than where it infiltrated, under the force of gravity or gravity induced pressures. Groundwater tends to move slowly and is replenished slowly, so it can remain in aquifers for thousands of years.
- The transformation of water from liquid to gas phases as it moves from the ground or bodies of water into the overlying atmosphere. The source of energy for evaporation is primarily solar radiation. Evaporation often implicitly includes transpiration from plants, though together they are specifically referred to as evapotranspiration. Total annual evapotranspiration amounts to approximately 505,000 km3 (121,000 cu mi) of water, 434,000 km3 (104,000 cu mi) of which evaporates from the oceans. 86% of global evaporation occurs over the ocean.
- The state change directly from solid water (snow or ice) to water vapor by passing the liquid state.
- This refers to changing of water vapor directly to ice.
- The movement of water through the atmosphere. Without advection, water that evaporated over the oceans could not precipitate over land.
- The transformation of water vapor to liquid water droplets in the air, creating clouds and fog.
- The release of water vapor from plants and soil into the air.
- Water flows vertically through the soil and rocks under the influence of gravity.
- Plate tectonics
- Water enters the mantle via subduction of oceanic crust. Water returns to the surface via volcanism.
The water cycle involves many of these processes.
|Reservoir||Average residence time|
|Glaciers||20 to 100 years|
|Seasonal snow cover||2 to 6 months|
|Soil moisture||1 to 2 months|
|Groundwater: shallow||100 to 200 years|
|Groundwater: deep||10,000 years|
|Lakes (see lake retention time)||50 to 100 years|
|Rivers||2 to 6 months|
The residence time of a reservoir within the hydrologic cycle is the average time a water molecule will spend in that reservoir (see adjacent table). It is a measure of the average age of the water in that reservoir.
Groundwater can spend over 10,000 years beneath Earth's surface before leaving. Particularly old groundwater is called fossil water. Water stored in the soil remains there very briefly, because it is spread thinly across the Earth, and is readily lost by evaporation, transpiration, stream flow, or groundwater recharge. After evaporating, the residence time in the atmosphere is about 9 days before condensing and falling to the Earth as precipitation.
The major ice sheets – Antarctica and Greenland – store ice for very long periods. Ice from Antarctica has been reliably dated to 800,000 years before present, though the average residence time is shorter.
In hydrology, residence times can be estimated in two ways. The more common method relies on the principle of conservation of mass and assumes the amount of water in a given reservoir is roughly constant. With this method, residence times are estimated by dividing the volume of the reservoir by the rate by which water either enters or exits the reservoir. Conceptually, this is equivalent to timing how long it would take the reservoir to become filled from empty if no water were to leave (or how long it would take the reservoir to empty from full if no water were to enter).
Changes over time
The water cycle describes the processes that drive the movement of water throughout the hydrosphere. However, much more water is "in storage" for long periods of time than is actually moving through the cycle. The storehouses for the vast majority of all water on Earth are the oceans. It is estimated that of the 332,500,000 mi3 (1,386,000,000 km3) of the world's water supply, about 321,000,000 mi3 (1,338,000,000 km3) is stored in oceans, or about 97%. It is also estimated that the oceans supply about 90% of the evaporated water that goes into the water cycle.
During colder climatic periods, more ice caps and glaciers form, and enough of the global water supply accumulates as ice to lessen the amounts in other parts of the water cycle. The reverse is true during warm periods. During the last ice age, glaciers covered almost one-third of Earth's land mass with the result being that the oceans were about 122 m (400 ft) lower than today. During the last global "warm spell," about 125,000 years ago, the seas were about 5.5 m (18 ft) higher than they are now. About three million years ago the oceans could have been up to 50 m (165 ft) higher.
The scientific consensus expressed in the 2007 Intergovernmental Panel on Climate Change (IPCC) Summary for Policymakers is for the water cycle to continue to intensify throughout the 21st century, though this does not mean that precipitation will increase in all regions. In subtropical land areas — places that are already relatively dry — precipitation is projected to decrease during the 21st century, increasing the probability of drought. The drying is projected to be strongest near the poleward margins of the subtropics (for example, the Mediterranean Basin, South Africa, southern Australia, and the Southwestern United States). Annual precipitation amounts are expected to increase in near-equatorial regions that tend to be wet in the present climate, and also at high latitudes. These large-scale patterns are present in nearly all of the climate model simulations conducted at several international research centers as part of the 4th Assessment of the IPCC. There is now ample evidence that increased hydrologic variability and change in climate has and will continue to have a profound impact on the water sector through the hydrologic cycle, water availability, water demand, and water allocation at the global, regional, basin, and local levels. Research published in 2012 in Science based on surface ocean salinity over the period 1950 to 2000 confirm this projection of an intensified global water cycle with salty areas becoming more saline and fresher areas becoming more fresh over the period:
Fundamental thermodynamics and climate models suggest that dry regions will become drier and wet regions will become wetter in response to warming. Efforts to detect this long-term response in sparse surface observations of rainfall and evaporation remain ambiguous. We show that ocean salinity patterns express an identifiable fingerprint of an intensifying water cycle. Our 50-year observed global surface salinity changes, combined with changes from global climate models, present robust evidence of an intensified global water cycle at a rate of 8 ± 5% per degree of surface warming. This rate is double the response projected by current-generation climate models and suggests that a substantial (16 to 24%) intensification of the global water cycle will occur in a future 2° to 3° warmer world.
Glacial retreat is also an example of a changing water cycle, where the supply of water to glaciers from precipitation cannot keep up with the loss of water from melting and sublimation. Glacial retreat since 1850 has been extensive.
Human activities that alter the water cycle include:
Effects on climate
The water cycle is powered from solar energy. 86% of the global evaporation occurs from the oceans, reducing their temperature by evaporative cooling. Without the cooling, the effect of evaporation on the greenhouse effect would lead to a much higher surface temperature of 67 °C (153 °F), and a warmer planet.
Effects on biogeochemical cycling
While the water cycle is itself a biogeochemical cycle, flow of water over and beneath the Earth is a key component of the cycling of other biogeochemicals. Runoff is responsible for almost all of the transport of eroded sediment and phosphorus from land to waterbodies. The salinity of the oceans is derived from erosion and transport of dissolved salts from the land. Cultural eutrophication of lakes is primarily due to phosphorus, applied in excess to agricultural fields in fertilizers, and then transported overland and down rivers. Both runoff and groundwater flow play significant roles in transporting nitrogen from the land to waterbodies. The dead zone at the outlet of the Mississippi River is a consequence of nitrates from fertilizer being carried off agricultural fields and funnelled down the river system to the Gulf of Mexico. Runoff also plays a part in the carbon cycle, again through the transport of eroded rock and soil.
Slow loss over geologic time
The hydrodynamic wind within the upper portion of a planet's atmosphere allows light chemical elements such as Hydrogen to move up to the exobase, the lower limit of the exosphere, where the gases can then reach escape velocity, entering outer space without impacting other particles of gas. This type of gas loss from a planet into space is known as planetary wind. Planets with hot lower atmospheres could result in humid upper atmospheres that accelerate the loss of hydrogen.
History of hydrologic cycle theory
Floating land mass
In ancient times, it was widely thought that the land mass floated on a body of water, and that most of the water in rivers has its origin under the earth. Examples of this belief can be found in the works of Homer (circa 800 BCE).
In the ancient near east, Hebrew scholars observed that even though the rivers ran into the sea, the sea never became full (). Some scholars conclude that the water cycle was described completely during this time in this passage: "The wind goeth toward the south, and turneth about unto the north; it whirleth about continually, and the wind returneth again according to its circuits. All the rivers run into the sea, yet the sea is not full; unto the place from whence the rivers come, thither they return again" (, KJV). Scholars are not in agreement as to the date of Ecclesiastes, though most scholars point to a date during the time of King Solomon, son of David and Bathsheba, "three thousand years ago, there is some agreement that the time period is 962-922 BCE. Furthermore, it was also observed that when the clouds were full, they emptied rain on the earth (). In addition, during 793-740 BC a Hebrew prophet, Amos, stated that water comes from the sea and is poured out on the earth (, ).
In the Biblical Book of Job, dated between 7th and 2nd centuries BCE, there is a description of precipitation in the hydrologic cycle, "For he maketh small the drops of water: they pour down rain according to the vapour thereof; Which the clouds do drop and distil upon man abundantly" (, KJV).
Precipitation and percolation
In the Adityahridayam (a devotional hymn to the Sun God) of Ramayana, a Hindu epic dated to the 4th century BC, it is mentioned in the 22nd verse that the Sun heats up water and sends it down as rain. By roughly 500 BCE, Greek scholars were speculating that much of the water in rivers can be attributed to rain. The origin of rain was also known by then. These scholars maintained the belief, however, that water rising up through the earth contributed a great deal to rivers. Examples of this thinking included Anaximander (570 BCE) (who also speculated about the evolution of land animals from fish) and Xenophanes of Colophon (530 BCE). Chinese scholars such as Chi Ni Tzu (320 BC) and Lu Shih Ch'un Ch'iu (239 BCE) had similar thoughts. The idea that the water cycle is a closed cycle can be found in the works of Anaxagoras of Clazomenae (460 BCE) and Diogenes of Apollonia (460 BCE). Both Plato (390 BCE) and Aristotle (350 BCE) speculated about percolation as part of the water cycle.
Up to the time of the Renaissance, it was thought that precipitation alone was insufficient to feed rivers, for a complete water cycle, and that underground water pushing upwards from the oceans were the main contributors to river water. Bartholomew of England held this view (1240 CE), as did Leonardo da Vinci (1500 CE) and Athanasius Kircher (1644 CE).
The first published thinker to assert that rainfall alone was sufficient for the maintenance of rivers was Bernard Palissy (1580 CE), who is often credited as the "discoverer" of the modern theory of the water cycle. Palissy's theories were not tested scientifically until 1674, in a study commonly attributed to Pierre Perrault. Even then, these beliefs were not accepted in mainstream science until the early nineteenth century.
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2 'Origins and History of Hydrology', Dijon, May, 9-11, 2001. Archived (PDF) from the original on 2014-10-11. Retrieved 2014-02-26.
|Wikimedia Commons has media related to Water cycle.|
- The Water Cycle, United States Geological Survey
- The Water Cycle for Kids, United States Geological Survey
- The water cycle, from Dr. Art's Guide to the Planet.
- Water cycle slideshow, 1 Mb Flash multilingual animation highlighting the often-overlooked evaporation from bare soil, from managingwholes.com.
- Will the wet get wetter and the dry drier? - Climate research summary from NOAA Geophysical Fluid Dynamics Laboratory including text, graphics, and animations | <urn:uuid:1c8e3857-3a42-4b40-9061-95c91c481838> | 4 | 5,443 | Knowledge Article | Science & Tech. | 56.599039 | 95,550,404 |
Researchers hope that the recent finding of the Higgs Boson particle – also known as the God particle as it helps to explain how mass is created – may someday benefit technology and diverse fields of science.
The particle was discovered in experiments at the European Organization for Nuclear Research (CERN) lab near Geneva, Switzerland.
In fact, the technology used in the CERN lab has already led to the development of grid computing and may soon be used in various gadgets – much like technology from space missions finding their way in products on Earth, according to news reports.
Grid computing could become more important than even the Internet, according to scientists from the Saha Institute of Nuclear Physics in India.
“Grid Computing, which connects hundreds of institutes working on the Large Hydron Collidor experiment at CERN through a network that receives shares and analyzes the huge volume of data generated, could be used to share information in various fields, including medicine,” according to a report from The Times of India.
In fact, software generated at CERN, known as GEANT, is already helping in cancer treatment.
"Grid computing is the first real, significant off-shoot of this historic experiment,” Subir Sarkar, a researcher at SINP, told The Times of India. “It distributes information at a lightning speed. More importantly, it is a system that stores data in a structured manner and lets the user search for it even more precisely than the Internet."
Close to one hundred CMS groups worldwide took part in the grid computing network, The Times added.
"The CERN grid computing system gives you access to information faster than any other search engine that has been devised so far," Sarkar said.
There could be lots of future data sharing through grid computing, too, Sarkar said. Also, another spin-off from CERN could be smaller and quicker detectors that can be used in electronic gadgets.
In Punjab, India, one graduate student in nematology, Harjot Singh, told the Times of India that "[the] discovery of any new particle helps a great deal to unlock the mysteries of universe. This discovery will not only be beneficial to physicists but [the] God particle will also help research in biology and chemistry."
"The subatomic particles not only help in research, but also have widespread use in healthcare, the food industry and nuclear energy generation," said Satvir Singh Hans, a veterinary sciences student at Punjab Agricultural University. A research fellow in plant pathology, Harpreet Kaur, said that, "From iPhones to computers, all this equipment uses our knowledge on the sub-atomic particles.”
Meanwhile, the question was raised if the finding will impact big data. “In big data and analytics I don’t see a single insight like why do all particles have mass,” IBM Research’s Software vice president David McQueeney told The Washington Post in a video interview. “I see different insights.” One such issue is the understanding of human language, he said.
In a more practical sphere, Linux was apparently praised by a CERN staff member for its use in finding the Higgs Boson particle.
"Linux (specifically, Scientific Linux and Ubuntu) had a vital role in the discovery of the new boson at CERN," one researcher wrote on Reddit. "We use it every day in our analyses, together with hosts of open software, such as ROOT, and it plays a major role in the running of our networks of computers (in the grid etc.) used for the intensive work in our calculations."
"In terms of data analysis, Windows could be used in principle,” the researcher added in an online discussion, as reported by IT World. “We could also use some type of device that manipulates symbols on a strip of tape according to a simple table of rules. Linux is used because it is most appropriate for the job. Linux is ubiquitous in HPC [high-performance computing] and we use a lot of computing power in LHC [Large Hadron Collider] physics, so the arguments for the use of Linux in HPC are very similar to the arguments for the use of Linux in LHC physics analyses."
"The fact is that Linux was the operating system used in the overwhelming majority of the analyses contributing to the discovery," he said. "So, in that sense I think I am justified in claiming that Linux played a vital role in the discovery."
When the WannaCry ransomware attacked companies all over the world in 2017, experts soon realized it was meant to be stopped by regular updating. Even…
TMC recently announced the launch of three new artificial intelligence events under the banner of The New Intelligence. I recently spoke with TMC's Ex…
Organizations must align internally to achieve effective innovation. Companies should consider creating cross-functional teams or, at a minimum, incre…
The three events that are part of The New Intelligence are all about how businesses and service providers, and their customers, can benefit from artif…
TMC announced the launch of The New Intelligence conference and expo - The Event Powering the AI Revolution. This exciting new event will take place o… | <urn:uuid:08d8b672-0fb4-4437-87c7-a9196298a93f> | 3.328125 | 1,071 | Content Listing | Science & Tech. | 34.555325 | 95,550,429 |
|Acids and Bases|
In chemistry, a superbase is an extremely basic compound or caustic substance that has a high affinity for protons. The hydroxide ion is the strongest base possible in aqueous solutions, but bases that exist with much greater strengths than the bases that could exist in aqueous solutions are possible. Such bases are valuable in organic synthesis and are fundamental to physical organic chemistry. Superbases have been described and used since the 1850s. Reactions involving superbases often require special techniques since they are destroyed by water and atmospheric carbon dioxide as well as oxygen. Inert atmosphere techniques and low temperatures minimize these side reactions.
Superbase is defined as an organic compound whose basicity is greater than that of proton sponge, which has a pKa of 12.1. Strong superbases can be prepared from extending the hydrogen bond network of multiple amino groups substituted on an aromatic core. Superbases are of great interest to practicing organic chemists due to their reactivity as well as good solubility in organic solvents. Superbases are also important environmentally as they have recently been found to participate in CO2 fixation.
IUPAC defines superbases simply as a "compound having a very high basicity, such as lithium diisopropylamide." Caubère defines superbases qualitatively but more precisely: "The term superbases should only be applied to bases resulting from a mixing of two (or more) bases leading to new basic species possessing inherent new properties. The term superbase does not mean a base is thermodynamically and/or kinetically stronger than another, instead it means that a basic reagent is created by combining the characteristics of several different bases."
Superbases have also been defined semi-quantitatively as any species with a higher absolute proton affinity (APA = 245.3 kcal/mol) and intrinsic gas phase basicity (GB = 239 kcal/mol) than Alder's canonical proton sponge (1,8-bis-(dimethylamino)-naphthalene).
Classes of superbases
Organic superbases are almost always charge-neutral, nitrogen-containing species. Despite enormous proton affinity, organosuperbases exhibit low nucleophilicity. Increasingly important in organic synthesis, these include the phosphazenes, amidines, and guanidines. Other organic compounds also meet the physicochemical or structural definitions of 'superbase'. Proton chelators like the aromatic proton sponges and the bispidines are also superbases. Multicyclic polyamines, like DABCO might also be loosely included in this category.
Organometallic compounds of reactive metals can be superbases, including organolithium and organomagnesium (Grignard reagent) compounds. Another type of organometallic superbase has a reactive metal exchanged for a hydrogen on a heteroatom, such as oxygen (unstabilized alkoxides) or nitrogen (metal amides such as lithium diisopropylamide). A desirable property in many cases is low nucleophilicity, i.e. a non-nucleophilic base. Unhindered alkyllithiums, for example, cannot be used with electrophiles such as carbonyl groups, because they attack the electrophiles as nucleophiles.
The Schlosser base (or Lochmann-Schlosser base), the combination of n-butyllithium and potassium tert-butoxide, is a commonly used superbase. n-Butyllithium and potassium tert-butoxide form a mixed aggregate of greater reactivity than either reagent alone and with distinctly different properties in comparison to tert-butylpotassium.
Inorganic superbases are typically salt-like compounds with small, highly charged anions, e.g. lithium nitride. Alkali and alkaline earth metal hydrides such as potassium hydride and sodium hydride are superbases. Such species are insoluble in all solvents owing to the strong cation-anion interactions, but the surfaces of these materials are highly reactive and slurries are useful in synthesis.
Superbases in organic chemistry
The Strongest Superbases
The list of the strongest Superbases is given below. The serial number also represents the rank of the basicity of the compound.
- Ortho-diethynylbenzene dianion
- Meta-diethynylbenzene dianion
- Para-diethynylbenzene dianion
- Lithium monoxide anion
- Methyl anion
- "BBC - h2g2 - History of Chemistry - Acids and Bases". Retrieved 2009-08-30.
- Pozharskii, Alexander F.; Ozeryanskii, Valery A. "Proton Sponges and Hydrogen Transfer Phenomena". Mendeleev Communications. 22 (3): 117–124. doi:10.1016/j.mencom.2012.05.001.
- Bachrach, Steven M. (2012-11-02). "Extended Hydrogen Bond Network Enabled Superbases". Organic Letters. 14 (21): 5598–5601. doi:10.1021/ol302722s. ISSN 1523-7060.
- Légaré, Marc-André; Courtemanche, Marc-André; Fontaine, Frédéric-Georges (2014-08-28). "Lewis base activation of borane–dimethylsulfide into strongly reducing ion pairs for the transformation of carbon dioxide to methoxyboranes". Chemical Communications. 50 (77). doi:10.1039/c4cc04857a. ISSN 1364-548X.
- IUPAC, Compendium of Chemical Terminology, 2nd ed. (the "Gold Book") (1997). Online corrected version: (2006–) "superacid".
- Caubère, P (1993). "Unimetal super bases". Chemical Reviews. 93: 2317–2334. doi:10.1021/cr00022a012.
- Raczynska, Ewa D.; Decouzon, Michele; Gal, Jean-Francois; Maria, Pierre-Charles; Wozniak, Krzysztof; Kurg, Rhio; Carins, Stuart N. (3 June 2010). "ChemInform Abstract: Superbases and Superacids in the Gas Phase". ChemInform. 31 (33): no–no. doi:10.1002/chin.200033267.
- Superbases for Organic Synthesis Ed. Ishikawa, T., John Wiley and Sons, Ltd.: West Sussex, UK. 2009.
- Schlosser, M. (1988). "Superbases for organic synthesis". Pure Appl. Chem. 60 (11): 1627–1634. doi:10.1351/pac198860111627.
- MacMillan, David W. C. "The advent and development of organocatalysis". Nature. 455 (7211): 304–308. Bibcode:2008Natur.455..304M. doi:10.1038/nature07367. | <urn:uuid:d6fa8996-6f3a-40d7-ac32-9423d953123a> | 3.46875 | 1,535 | Knowledge Article | Science & Tech. | 33.853264 | 95,550,445 |
Mathematics for the Physical Sciences
by Herbert S Wilf
Publisher: Dover Publications 1962
Number of pages: 298
Advanced undergraduates and graduate students in the natural sciences receive a solid foundation in several fields of mathematics with this text. Topics include vector spaces and matrices; orthogonal functions; polynomial equations; asymptotic expansions; ordinary differential equations; conformal mapping; and extremum problems. Includes exercises and solutions. 1962 edition.
Home page url
Download or read it online for free here:
- Kluwer Academic Publishers
An open access resource designed specifically for the mathematics community. With more than 8,000 entries, illuminating 50,000 notions in mathematics, Encyclopaedia was the most up-to-date graduate-level reference work in the field of mathematics.
by M.A. Keasey, G.A. Kline, D.A. McIlhatten - The Blakiston company
The problems in this book emphasize the use of the mathematical principles so vital to a clear understanding of Engineering. They also furnish the necessary foundation for the later development of the Analytical Geometry and the Calculus.
by Walter E. Wynne, William Spraragen - Van Nostrand
The authors endeavored to supply a handy means of reference to theoretical and applied mathematics used in engineering, and while the first aim has been to make this a mathematical handbook, it also includes the underlying engineering applications.
by David Lippman - Lulu.com
A survey of math for liberal arts majors. Introduces contemporary mathematics topics: voting theory, weighted voting, fair division, graph theory, scheduling, growth models, finance math, statistics, and historical counting systems. | <urn:uuid:a6c7e358-1075-440a-b931-9be49f679c88> | 2.8125 | 352 | Content Listing | Science & Tech. | 24.09749 | 95,550,462 |
Buffering stdin and stdout
This is a program designed to speed up writing tapes on remote tape drives. When this program is put "in the pipe," two processes are started. One process reads from standard-in and the other writes to standard-out. Both processes communicate via shared memory.
Source Files (show merged sources derived from linked package)
|_link||0000000451451 Bytes||1441622128almost 3 years ago| | <urn:uuid:d75d06ab-6d84-4105-8bb6-9891c77b8384> | 2.90625 | 94 | Documentation | Software Dev. | 51.076635 | 95,550,464 |
Peridotite xenoliths which are thought to sample the upper mantle sometimes contain supra-chondritic Os-isotopic ratios.Radioactive dating is a method of dating rocks and minerals using radioactive isotopes.Isochrons are created by analysing several samples believed to have formed at the same time from a common source.
For example, the boundaries of many Phanerozoic systems, epochs, and stages are marked by the deposition of black shale units, several of which are coincident with mass extinction events.
Suitable lithologies for Re-Os geochronology include black shales and organic-rich carbonates.
In addition to geochronology data, the Re-Os geochronometer provides the Os isotope composition (Os = 0.12) derived from cosmic dust and hydrothermal alteration of oceanic crust.
As such, the Re-Os geochronometer can be used to directly date some stratigraphic boundaries.
Proterozoic sedimentary successions often record enormous portions of geological time, yet many of them lack volcanic horizons and are bereft of fossils suitable for relative age dating. | <urn:uuid:cafe28d1-4898-41fc-86c2-75261f59536d> | 3.859375 | 240 | Knowledge Article | Science & Tech. | 13.245556 | 95,550,479 |
- Museum of Paleontology, University of California, Berkeley
Top | See original
Following modified from Museum of Paleontology, University of California, Berkeley
Introduction to Placozoa
The Most Simple of All Known
Placozoans are tiny amazing animals.
Very little is known about them because they have never been observed in their natural habitat. No one knows what substrate they live on or what they eat in nature. It is even unknown whether or not they reproduce sexually like most animals. They were discovered in the late 1880's living on the glass walls of an aquarium in a European laboratory. Since then, most of what has been learned about their biology has come from studying cultures of them kept alive in various laboratories around the world. Not surprisingly, given their small size and squishy nature, fossil placozoans have yet to be discovered.
Placozoans are extremely simple animals. Perhaps not coincidentally, they also have the smallest amount of DNA ever measured for any type of animal. Their bodies are made up of a few thousand cells of just four types. You can compare this to
, which have anywhere from 10 to 20 different kinds of cells, to
, which have roughly 90 different cell types, and to you and other
, which have over 200 different types of cells. Placozoans are transparent, flat, round (up to 3 millimeters across), and have two distinct sides. A tissue layer composed of two types of cells, column-shaped
with cilia and
without cilia, make up the ventral (or bottom) surface. The upper dorsal surface consists of a layer of just
, which are ciliated and flattened toward the outside of the animal. The image above shows the dorsal surface of a small specimen (just over 4/10ths of a millimeter in diameter) seen from above through a microscope. The dorsal and ventral tissues appear to correspond to ectoderm and endoderm, the outer and inner tissue layers of most animals, but it is not yet known which is endoderm and which is ectoderm. The fourth type of placozoan cells are called
. These cells are star-shaped and reside in the space between the two tissue layers. The star shape results from thin extensions of the cells which connect to each other in a network. Cellular material such as microtubules and microfilaments traverse the extensions from fiber cell to fiber cell. It is hypothesized that this system of connected cells in important in coordinating the movement of placozoans. Placozoans can move in two ways, by gliding on their cilia and by changing their shape like an amoeba.
Placozoan Feeding and Reproduction
In the laboratory, placozoans have been kept alive by feeding them the flagellated
. It is unknown what placozoans feed on in nature; they may feed on a number of different organisms. A placozoan feeds with its ventral surface, which produces digestive enzymes. Often, individuals contract part of the ventral surface into a sac where digestion may take place more efficiently. Placozoans can reproduce asexually by either binary fission or, less often, by budding. Some laboratory observations suggest that sexual reproduction may occur. When the population density becomes high, placozoans start to degenerate. Usually a single egg or oocyte develops in the interspace of a degenerating placozoan. Small cells (without flagella) that also form when placozoans degenerate are inferred to be sperm cells. After fertilization, which does not appear to have been documented, cleavage begins. Development has only been observed to the 64 cell stage, at which point the cells cease to separate while the nuclear DNA continues to multiply until the nucleus bursts. Placozoan reproduction and development will probably not be fully understood until they are observed in their natural habitat.
The Phylogenetic Position of Placozoa
Some scientists have inferred that placozoans might be the earliest branch of animals (as shown in box A below) because they are so simple. However, the discovery that placozoan epithelial cells are connected by junctions of extracellular proteins (belt desmosomes), a condition present in all animals other than
, suggested that placozoans may have diverged later in the history of animals (box B below).
More recently, data from molecular sequences (18S) have indicated that placozoans might have diverged even later in the history of animals (box C above). If this latter view were true, it would imply that placozoans are secondarily simplified from more complex ancestors that had a nervous system. Interestingly enough, placozoans contain cells, which are dispersed around their outer edge, that react with antibodies against a neuropeptide that is present in the nervous system of cnidarians. In any event, the alternative hypotheses for the phylogenetic position of Placozoa within the animals need further testing with additional data.
Just two species of placozoans have ever been described,
. The latter of these has never been seen since its description in 1896, causing some to doubt its existence. The former, however, has been reported from many tropical and subtropical locations around the world, including: the Bermudas, the Caribbean Sea, Eastern Australia, the Great Barrier Reef, Guam, Hawaii, Japan, the Mediterranean Sea, Palau, Papua New Guinea, the Red Sea, Vietnam, and Western Samoa. This prompts the question of whether
is really a single species. Furthermore, placozoans are so cryptic that their diversity might be much greater than we realize.
Learn more about
from Richard L. Howey, whose page "
A Weird Wee Beastie
", is available at
Buchholz, K. and Ruthmann, A., 1995, The mesenchyme-like layer of the fiber cells of
(Placozoa), a syncytium,
Zeitschrift fuer Naturforschung Section C Biosciences
, 50, 282-285.
Collins, A. G., 1998, Evaluating multiple alternative hypotheses for the origin of Bilateria: An analysis of 18S molecular evidence,
Proceedings of the National Academy of Sciences, USA
, 95, 15458-15463.
Grell, K. C. and Lopez-Ochoterena, E., 1987, A new record of
F. E. Schulze (Phylum Placozoa) in the Mexican Caribbean Sea,
Anales del Instituto de Ciencias del Mar y Limnologia Universidad Nacional Autonoma de Mexico
, 14, 255-256.
Grell, K. G. and Ruthmann, A., 1991, Placozoa, in F. W. Harrison and W. J. A (ed.),
Microscopic Anatomy of Invertebrates, Vol. 2. Placozoa, Porifera, Cnidaria, and Ctenophora
(New York: Wiley-Liss), pp. 13-28.
Pearse, V. B., 1989, Growth and behavior of
: First record of the phylum Placozoa in Hawaii [USA],
, 43, 117-121.
Schuchert, P., 1993,
(Phylum Placozoa) Has Cells That React with Against the Neuropeptide Rf Amide,
(Copenhagen), 74, 115-117.
Updated: 2018-07-19 23:47:21 gmt | <urn:uuid:184c73d7-41d8-4f24-bdd9-7c940e3dfdd9> | 3.859375 | 1,577 | Knowledge Article | Science & Tech. | 42.890268 | 95,550,483 |
Most proteins need to interact physically with other proteins to be able to perform their biological functions; the identification of new protein-binding partners for a protein of interest may therefore be a key strategy in defining the mechanism of action for a particular protein. Many different approaches to studying protein-protein interactions exist, but identifying which interactions are biologically significant is not trivial. Thus, once an interaction is found, the first step is to validate the suggested interactions using genetic, biochemical, and cell-biological approaches. Here we will focus on three complementary protein interaction approaches: (a) the yeast two-hybrid (YTH) system, a genetic assay performed in living yeast cells, which can be used both to identify proteins that bind to a protein of interest and to determine domains or residues critical for an interaction; and two biochemical approaches, (b) the coimmunoprecipitation of interacting proteins with a specific antibody; and (c) the far-Western method that can show direct physical interaction of two proteins.
KeywordsActivation Domain ADH1 Promoter Bait Plasmid GAL4 Activation Domain Prey Plasmid
- 2.Sambrook, J. and Russell, D. W. (2001) Molecular Cloning: A Laboratory Manual, 3rd ed., Cold Spring Harbor Laboratory Press, Cold Spring Harbor, NY.Google Scholar
- 3.Bartel, P. L., Chien, C.-T., Sternglanz, R., and Fields, S. (1993) Using the two-hybrid system to detect protein-protein interactions, in: Cellular Interactions in Development: A Practical Approach (Hartley, D. A., ed.), Oxford University Press, Oxford, England, pp. 153–179.Google Scholar | <urn:uuid:63ffd1c8-f758-44e4-b41f-e05d88a335ff> | 2.640625 | 362 | Academic Writing | Science & Tech. | 41.309764 | 95,550,488 |
The new technique, reported in the August edition of Physics World, would render nuclear waste harmless on timescales of just a few tens of years, instead of thousands.
Professor Claus Rolfs, leader of the group at Ruhr University in Bochum, Germany, said “The method we are proposing means that nuclear waste could probably be dealt with entirely within the lifetimes of the people that produce it. We would not have to put it underground and let our great-great-grandchildren pay the price for our high standard of living.”
The technique involves embedding the nuclear waste in a metal and cooling it to ultra-low temperatures. This speeds up the rate of decay of the radioactive materials potentially cutting their half lives by a factor of 100 or more.
Professor Rolfs added “We are currently investigating radium-226, a hazardous component of spent nuclear fuel with a half-life of 1600 years. I calculate that using this technique could reduce the half-life to 100 years. At best, I have calculated that it could be reduced to as little as two years. This would avoid the need to bury nuclear waste in deep repositories - a hugely expensive and difficult process.”
Rolfs developed the technique after trying to recreate experimentally the way in which atomic nuclei react in the centre of stars. Whilst using a particle collider to carry out his studies, he noticed that more nuclear fusion reactions happened in the collider if the atomic nuclei were encased in metal and cooled. Fusion involves light nuclei coalescing to form heavier nuclei, releasing energy in the process. Radioactive decay is the opposite: a particle is released from a nucleus. Rolfs believes that if cooling nuclei in metal enhances fusion, it could enhance the opposite reaction, namely speeding up the rate at which radioactive particles decay.
According to Rolfs, the lower temperature of the metal means that free electrons can get closer to the radioactive nuclei. These electrons accelerate positively charged particles towards the nuclei, thereby increasing the probability of fusion reactions, or in the opposite case, accelerate particles that are being ejected from the nucleus.
“We are working on testing the hypothesis with a number of radioactive nuclei at the moment and early results are promising”, he said. “It is early days, and much engineering research will need to be done to put this idea into practise, but I don’t think there will be any insurmountable technical barriers.”
Helen MacBain | 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....
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Typically, the behavior of a nonlinear system is described in mathematics by a nonlinear system of equations, which is a set of simultaneous equations in which the unknowns (or the unknown functions in the case of differential equations) appear as variables of a polynomial of degree higher than one or in the argument of a function which is not a polynomial of degree one. In other words, in a nonlinear system of equations, the equation(s) to be solved cannot be written as a linear combination of the unknown variables or functions that appear in them. Systems can be defined as nonlinear, regardless of whether known linear functions appear in the equations. In particular, a differential equation is linear if it is linear in terms of the unknown function and its derivatives, even if nonlinear in terms of the other variables appearing in it.
As nonlinear dynamical equations are difficult to solve, nonlinear systems are commonly approximated by linear equations (linearization). This works well up to some accuracy and some range for the input values, but some interesting phenomena such as solitons, chaos, and singularities are hidden by linearization. It follows that some aspects of the dynamic behavior of a nonlinear system can appear to be counterintuitive, unpredictable or even chaotic. Although such chaotic behavior may resemble random behavior, it is in fact not random. For example, some aspects of the weather are seen to be chaotic, where simple changes in one part of the system produce complex effects throughout. This nonlinearity is one of the reasons why accurate long-term forecasts are impossible with current technology.
Some authors use the term nonlinear science for the study of nonlinear systems. This is disputed by others:
Using a term like nonlinear science is like referring to the bulk of zoology as the study of non-elephant animals.
Additivity implies homogeneity for any rational α, and, for continuous functions, for any real α. For a complex α, homogeneity does not follow from additivity. For example, an antilinear map is additive but not homogeneous. The conditions of additivity and homogeneity are often combined in the superposition principle
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Anthropogenic biomes: a key contribution to earth-system scienceAuthor(s): Lilian Alessa; F. Stuart Chapin
Source: Trends in Ecology and Evolution. 23(10): 529-531
Publication Series: Scientific Journal (JRNL)
Station: Pacific Northwest Research Station
PDF: View PDF (958 KB)
DescriptionHuman activities now dominate most of the ice-free terrestrial surface. A recent article presents a classification and global map of human-influenced biomes of the world that provides a novel and potentially appropriate framework for projecting changes in earth-system dynamics.
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CitationAlessa, Lilian; Chapin, F. Stuart, III. 2008. Anthropogenic biomes: a key contribution to earth-system science. Trends in Ecology and Evolution. 23(10): 529-531.
Keywordsbiomes, social ecological systems, land use
- Modeling human-environmental systems
- Man's nature: innate determinants of response to natural environments
- Finding aroma clues in the human breath to diagnose diseases
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Date of publication: 2017-08-24 07:44
Mathew Maye, assistant professor of chemistry in SU’s College of Arts and Sciences , and Rabeka Alam, a chemistry . candidate, have discovered that the size and structure of custom, quantum nanorods could hold the key.
Thus, the rapid development in controllable nanomaterials synthesis as well as finely tuned surface engineering could allow researchers to design and fabricate various UCNP-based nanocomposites with highly integrated functionalities, useful for multimodal imaging and imaging-guided cancer therapies.
CLIMATE CHANGE The ocean is warming, and this might give some jellies a boost. The warmer water could help jelly embryos and larvae develop more quickly, allowing their populations to grow more quickly. And jellies that prefer warmer water will have more area to live in. However, this could also hurt some species as cold-water jelly species see their habitat shrink.
Polyps reproduce asexually by budding—when a polyp divides roughly in half to produce a new genetically identical polyp—or they can produce or transform into medusae, depending on the type of jellyfish. Hydrozoan polyps bud medusae from their sides cubozoan polyps each transform into a medusa.
The exhibit Creatures of Light: Nature s Bioluminescence opens at the American Museum of Natural History on Saturday (March 86) and is scheduled to run until Jan. 6, 7568.
Additionally, some jellyfish have sensory structures called rhopalia, which contain receptors to detect light, chemicals and movement. One group of jellyfish, the cubozoan jellyfish, have complex eyes with lenses, corneas and retinas in their rhopalia. Although they respond to visual stimuli, scientists don’t know how the jellyfish interpret the images created by their eyes since they don’t have a brain with which to process them. Their nerve ring, a ring-shaped concentration of nerves found in jellyfish, seems to be involved, however.
That's pretty much what happens when an atom absorbs energy. An electron inside it jumps to a higher energy level, but makes the atom unstable. As the electron returns to its original level, it gives back the energy as a flash of light called a photon.
Because jellies have no bones or other hard parts, finding jellyfish fossils is rare. But in 7557, a group of scientists including Allen Collins from the Smithsonian National Museum of Natural History, discovered some beautifully-preserved jellyfish fossils buried in Utah from 555 million years ago. From around the same period, scientists have also found well-preserved comb jelly fossils in the Burgess Shale.
SCYPHOZOA are the most familiar jellyfish, including most of the bigger and more colorful jellies that interact with humans, and are sometimes called "true jellyfish" for this reason. Scyphozoa spend most of their lives in the medusa body form, and there are at least 755 species.
The past decade has witnessed an explosion of interest in the use of UCNPs as novel theranostic probes in biomedicine. As summarized in this review article, applications of UCNPs for photodynamic therapy, NIR triggered drug and gene delivery, as well as several other UCNP-based cancer approaches have been demonstrated. However, in the near future, there may still be many obstacles to be overcome.
Jellyfish have a complex life cycle: a single jellyfish reproduces both sexually and asexually during its lifetime, and takes on two different body forms.
STAUROZOA are the stalked jellyfishes , which don't float through the water like other jellies, but rather live attached to rocks or seaweed. They are trumpet-shaped, and mostly live in cold water. There are around 55 staurozoan species, many notable for their unique combination of beauty and camouflage. | <urn:uuid:2c43ef13-030d-4e64-b249-02047c7e9dba> | 3.125 | 822 | Academic Writing | Science & Tech. | 32.257182 | 95,550,540 |
The methods of biotechnology, such as directed microbiological synthesis, biochemical methods of breaking down complicated organic compounds (especially those using the biological catalysts — enzymes — and immuno-biological enzymes in particular), and the methods of fine organic synthesis have recently been very successfully applied to obtaining physiologically active substances (PAS’s). The substances that have been synthesized and biosynthesized include proteins (enzymes), polypeptides and amino acids, nucleic acids, nucleotides, nucleosides, polysaccharides, low-molecular-weight hydrocarbons, and a variety of others that have a physiological effect, such as antibiotics, regulators of various types, hormones, and vitamins. Both natural and synthesized PAS’s are at first complex mixtures of substances, and the initial solutions may contain tens, hundreds, or even thousands of components, many of which are closely related to the desired product in terms of their physico-chemical properties. If the products of a chemical synthesis are very specific (the intermediate and side products being only admixtures), then during a biosynthesis a multicomponent solution will be formed. The culture liquid obtained is a very complicated mixture from which we have to isolate only one, or a small number of, components. Natural products too are no less important and include primary extracts from animal and vegetable tissues and solutions that have been obtained at the first stage of separating out a natural PAS. In all these, the separation of an individual or very pure PAS is a complex problem that can be solved using modern and effective physico-chemical methods. This then is the subject area of physico-chemical biotechnology.
KeywordsElution Chromatography Preparative Chromatography Multicomponent Solution Frontal Process Fine Organic Synthesis
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Last night I gave a talk at a Perth Linux User's Group meetup about doing Linuxy stuff on small machines:
Frock is a little experimental tool for writing PHP scripts using Clojure-like LISP syntax.
If you want to see what the code looks like, here's an example which fetches and lists top news items from the Hacker News API.
Frock could be interesting to you if you are LISP or Clojure programmer writing a web application which is mostly front-end code, but which needs some small amount of server side logic for e.g. proxying, authentication, data persistence etc. and you want this application to be easily deployable by semi-technical users on commodity hosting.
Basically if your target audience is graphic designers, you like Clojure, and your backend requirements are slim, then you might be interested.
PHP is an old server-side web development language which is simultaneously loathed by software developers everywhere, and also wildly popular and widely deployed. To reconcile this paradox let's take a look at some pros and cons of PHP.
- Ugly language semantics & features.
- Dubious security record.
- Much awful legacy code lying around.
- User-friendly app deployments (simply copy files to server).
- Widely available on internet servers.
- Mature language and ecosystem.
- Excellent documentation.
- Much useful tech bundled ("batteries included").
The pros make PHP quite democratic. It's very easy to install PHP code on widely available, cheap, commodity hosting. It's easy to get started writing PHP applications; the PHP binary comes pre-installed on OSX for example. PHP contains a lot of capabilities by default: zipping files, opening sockets, encryption, command execution.
Frock exists to make the language semantics and features less of a con for brace wrangling LISP heads, whilst retaining the wide deployment surface and other democratic features of PHP.
I built a little blockchain-in-a-browser in ClojureScript to help understand the underlying algorithms.
You can simulate a network of peers by opening multiple browser tabs. Each peer can mine blocks and make transactions independently and the resulting blockchain will resolve conflicts correctly across all tabs.
A blockchain works by laying down a chain of blocks of transaction data.
Each block in the chain contains a cryptographic hash with two important properties:
- It proves a link to the previous block.
- It proves that difficult computational work has been done.
The proof-of-work is accomplished by iteratively updating a nonce until a low-probability hash is discovered.
These two properties mean a blockchain is digital amber.
If somebody wants to modify a transaction deep inside the amber it would be very difficult because they would have to re-create every layer of the blockchain by doing as much work as the original process required.
In my browser blockchain the hashing is implemented like this:
(hash-object [timestamp transactions previous-hash nonce])
As you can see the previous block's hash is included in the current block.
The hashing is performed iteratively in a loop until a hash with at least one byte of leading zeroes is found:
(loop [c 0] (let [candidate-block (make-block (now) transactions previous-hash new-index (make-nonce))] (if (not= (aget (candidate-block :hash) 0) 0) (recur (inc c)) candidate-block))) | <urn:uuid:0f7eeae2-e5a3-4824-98b1-9eb6413d98cb> | 2.515625 | 726 | Personal Blog | Software Dev. | 44.01281 | 95,550,587 |
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.
Prepare for the International Asteroid Day, which not only marks a devastating asteroid event in 1908 but also encourages awareness of near-Earth objects, their awe-inspiring dangers, and what can be done to minimize the risks from these space rocks.
Japan's spacecraft Hayabusa2 is getting close to its destination: the carbon-rich asteroid Ryugu that turns out to be shaped like the gem flourite. At this distance, the space rock's peaks and craters are tantalizingly clear.
A bright fireball lit up the sky in Botswana, Africa. It is the result of an asteroid impact that astronomers detected just hours before it collided with Earth.
An asteroid larger than a football field is speeding toward Earth, and it's expected to whiz past just a hair's breadth away on Tuesday, May 15. It will be Earth's closest ever encounter to a space rock this size.
With so much asteroids speeding through space, is a crash imminent?
The precious metals of 16 Psyche is said to be worth many times more than the global economy.
Saturn's large, icy, oceanic moon Enceladus may have been tipped away from its original axis.
Had the extinction-level asteroid struck the planet in a different time and location, the outcome may have been different. If it landed in the ocean, dinosaurs could have survived.
A massive asteroid passed by Earth on April 19 and might be visible for a couple of days. This is the largest asteroid of its size to approach the planet.
A giant asteroid will approach the planet on April 19. It will fly very close that stargazers will be able to see it using small telescopes.
The Analemma Tower may be a new name for some people, however it is actually being pegged as the "world's tallest building."
Tsunamis could have stirred huge amounts of Martian ocean billions of years ago. A new study suggests that deposits discovered are remains of giant tsunamis caused by asteroid impacts.
New theory suggests that the Mars' moon Phobos might actually collapse one day and form set of rings around the red planet.
An extinction-level asteroid impact, one-third the size of the one that killed the dinosaur, may have caused the extinction of 35 species of animals and the obliteration of the Clovis Native American civilization. | <urn:uuid:87d5aecf-0914-4e1c-97e5-6facc52e1ddf> | 3.984375 | 520 | Content Listing | Science & Tech. | 49.136506 | 95,550,611 |
If I am wearing a bright red shirt and I take into account light and pigments why would the shirt appear red to someone?© BrainMass Inc. brainmass.com July 21, 2018, 9:25 pm ad1c9bdddf
The pigments in the shirt can be related to the pigments in photosynthesis.
<br>If the visible portion of the light spectrum is divided into thirds, the predominant colors are red, yellow and blue. These three colors are considered the primary colors of the visible light spectrum. A pigment is a molecule that absorbs certain wavelengths and ... | <urn:uuid:32f07dc9-814e-43df-a199-cbe63a2c239d> | 2.921875 | 121 | Q&A Forum | Science & Tech. | 69.559444 | 95,550,626 |
Zumf makes spectacles for the residents of the planet Zargon, who have either 3 eyes or 4 eyes. How many lenses will Zumf need to make all the different orders for 9 families?
There are 44 people coming to a dinner party. There are 15 square tables that seat 4 people. Find a way to seat the 44 people using all 15 tables, with no empty places.
There is a clock-face where the numbers have become all mixed up. Can you find out where all the numbers have got to from these ten statements?
You have two egg timers. One takes 4 minutes exactly to empty and the other takes 7 minutes. What times in whole minutes can you measure and how?
Winifred Wytsh bought a box each of jelly babies, milk jelly bears, yellow jelly bees and jelly belly beans. In how many different ways could she make a jolly jelly feast with 32 legs?
You have 5 darts and your target score is 44. How many different ways could you score 44?
How could you put eight beanbags in the hoops so that there are four in the blue hoop, five in the red and six in the yellow? Can you find all the ways of doing this?
This magic square has operations written in it, to make it into a maze. Start wherever you like, go through every cell and go out a total of 15!
There are 4 jugs which hold 9 litres, 7 litres, 4 litres and 2 litres. Find a way to pour 9 litres of drink from one jug to another until you are left with exactly 3 litres in three of the jugs.
Arrange eight of the numbers between 1 and 9 in the Polo Square below so that each side adds to the same total.
This task, written for the National Young Mathematicians' Award 2016, invites you to explore the different combinations of scores that you might get on these dart boards.
Can you put plus signs in so this is true? 1 2 3 4 5 6 7 8 9 = 99 How many ways can you do it?
Using the statements, can you work out how many of each type of rabbit there are in these pens?
Cherri, Saxon, Mel and Paul are friends. They are all different ages. Can you find out the age of each friend using the information?
There are 78 prisoners in a square cell block of twelve cells. The clever prison warder arranged them so there were 25 along each wall of the prison block. How did he do it?
Find the sum and difference between a pair of two-digit numbers. Now find the sum and difference between the sum and difference! What happens?
In a Magic Square all the rows, columns and diagonals add to the 'Magic Constant'. How would you change the magic constant of this square?
This challenge focuses on finding the sum and difference of pairs of two-digit numbers.
This task follows on from Build it Up and takes the ideas into three dimensions!
There are to be 6 homes built on a new development site. They could be semi-detached, detached or terraced houses. How many different combinations of these can you find?
Can you arrange 5 different digits (from 0 - 9) in the cross in the way described?
This problem is based on the story of the Pied Piper of Hamelin. Investigate the different numbers of people and rats there could have been if you know how many legs there are altogether!
Try adding together the dates of all the days in one week. Now multiply the first date by 7 and add 21. Can you explain what happens?
This task, written for the National Young Mathematicians' Award 2016, involves open-topped boxes made with interlocking cubes. Explore the number of units of paint that are needed to cover the boxes. . . .
There were chews for 2p, mini eggs for 3p, Chocko bars for 5p and lollypops for 7p in the sweet shop. What could each of the children buy with their money?
This challenge asks you to investigate the total number of cards that would be sent if four children send one to all three others. How many would be sent if there were five children? Six?
Fill in the missing numbers so that adding each pair of corner numbers gives you the number between them (in the box).
In how many ways could Mrs Beeswax put ten coins into her three puddings so that each pudding ended up with at least two coins?
Suppose there is a train with 24 carriages which are going to be put together to make up some new trains. Can you find all the ways that this can be done?
Fill in the numbers to make the sum of each row, column and diagonal equal to 34. For an extra challenge try the huge American Flag magic square.
Find out what a Deca Tree is and then work out how many leaves there will be after the woodcutter has cut off a trunk, a branch, a twig and a leaf.
We can arrange dots in a similar way to the 5 on a dice and they usually sit quite well into a rectangular shape. How many altogether in this 3 by 5? What happens for other sizes?
48 is called an abundant number because it is less than the sum of its factors (without itself). Can you find some more abundant numbers?
Arrange three 1s, three 2s and three 3s in this square so that every row, column and diagonal adds to the same total.
This task, written for the National Young Mathematicians' Award 2016, focuses on 'open squares'. What would the next five open squares look like?
This problem is based on a code using two different prime numbers less than 10. You'll need to multiply them together and shift the alphabet forwards by the result. Can you decipher the code?
Move from the START to the FINISH by moving across or down to the next square. Can you find a route to make these totals?
Watch this animation. What do you notice? What happens when you try more or fewer cubes in a bundle?
Use these head, body and leg pieces to make Robot Monsters which are different heights.
The clockmaker's wife cut up his birthday cake to look like a clock face. Can you work out who received each piece?
Place the numbers from 1 to 9 in the squares below so that the difference between joined squares is odd. How many different ways can you do this?
If each of these three shapes has a value, can you find the totals of the combinations? Perhaps you can use the shapes to make the given totals?
A group of children are using measuring cylinders but they lose the labels. Can you help relabel them?
Add the sum of the squares of four numbers between 10 and 20 to the sum of the squares of three numbers less than 6 to make the square of another, larger, number.
Place the digits 1 to 9 into the circles so that each side of the triangle adds to the same total.
Find your way through the grid starting at 2 and following these operations. What number do you end on?
Look carefully at the numbers. What do you notice? Can you make another square using the numbers 1 to 16, that displays the same properties?
What is the sum of all the three digit whole numbers?
Using 3 rods of integer lengths, none longer than 10 units and not using any rod more than once, you can measure all the lengths in whole units from 1 to 10 units. How many ways can you do this?
In a square in which the houses are evenly spaced, numbers 3 and 10 are opposite each other. What is the smallest and what is the largest possible number of houses in the square? | <urn:uuid:f3031028-58ea-4bed-bd3e-990076a62a4a> | 2.546875 | 1,604 | Content Listing | Science & Tech. | 74.328594 | 95,550,629 |
|Acheron 2.0 displays the following fractal curves; :|
6680 visitors since Jan 2010
All pictures from Acheron 2.0
Introduction Back to Top
The euclidean geometry uses objects that have integer topological dimensions. A line or a curve is an object that have a topological dimension of one while a surface is described as an object with two topological dimensions and a cuve as an object with three dimensions. This geometry adequately describes the regular objects but failed to be applicable when it comes to consider natural irregular shapes.
Benoit B. Mandelbrot introduced a new concepts, that he called fractals, that are useful to describe natural shapes as islands, clouds, landscapes or other fragmented structures. According to Mandelbrot, the term fractals is derived from the latin adjective fractus meaning fragmented. According to Mandelbrot, a fractal can be defined as 'a set for which the Hausdorff-Besicovitch dimension strictly exceeds the topological dimension'. This clever mathematical definition, albeit quite obscure for non-initiated people, means that a fractal curve is a mathematical function that produce an image having a topological dimension between one and two. Intuitively, fractals can be seen as curves partially filling a two-dimentional area. These curves are often described as space-filling curves.
Fractals curves exhibit a very interesting property known as self-similarity. If you observe precisely the details of a fractal curve, it appears that a portion of the curve replicates exactly the whole curve but on a different scale. Mathematicians have in fact created geometrical fractal curves long before the introduction of the fractal geometry by Benoit Mandelbrot. Some of these curves are well-known as the Von Koch's snowflake or the triangle of Sierpinsky.
Construction Back to Top
As most of the fractal curves, the construction of the curve is based
on the recursive procedure.
The third iteration already gives an intricate pattern that require a much larger drawing to follow the construction rule visually. Playing with Acheron 2.0 will help learning the construction of this curve ...
The limit curve, obtained when iteration number tends to infinity, covers
the entire area, object known as a space-filling curve.
Take a grid with a side of length N. The total length of the curve is the sum of the vertical and Horizontal segments ( noted S) and the oblique segments ( noted O).
The number of Horizontal and Vertical segments is computed using the number of segments generated at the previous recursion, the number of segments of the recursion 1 being equal to 8 ( S1 = 8).
SRec = (SRec-1 * 4) + 8
This leads to a generalized formula for the number of Horizontal and Vertical segments:
SRec = ((8 * 4 Rec) - 8) / 3
The number of oblique segments is computed using the number of segments generated at the previous recursion, the number of segments of the recursion 1 being equal to 12 ( O1 = 12).
ORec = (ORec-1 * 4) - 4
This leads to a generalized formula for the number of Oblique segments:
ORec = ((8 * 4 Rec) + 4) / 3
The Size of the horizontal and vertical segments changes with the recursion according to the following formula:
lsRec = N / (2Rec * 4)
This is summarized in the table below:
As expected from the principe of curve construction, the ratio of the total number of segments between two successive iterations tends to 4.
Considering N being of unary length and by combining the different formula showed above, we have the following figures for the total length:
Roughly, the length is doubling at each iteration. Graphically, it gives:
The number of full squares is equal to:
SRec = ((16 * 4 Rec) - 16) / 3
The number of half squares is equal to:
ORec = ((8 * 4 Rec) + 4) / 3
Combining these two formula gives the total number of squares:
NumberRec = ((20 * 4 Rec) - 14) / 3)
To compute the total area, the total square number covered by the curve is divided by the total number of squares of the grid area:
AreaRec = ( N * (20 * 4 Rec) - 14) / (3 * 4Rec * 16))
which finally simplifies to:
AreaRec = N * (( 10 * 4 Rec) - 7) / (24 * 4 Rec)
As the number of recursion increases, the terms 10 * 4 Rec and 24 * 4 Rec become so large that the correction by 7 have smaller and smaller influence and can be neglected. The formula tends to:
AreaRec = N * ( 10 * 4 Rec) / (24 * 4 Rec)
which finally simplifies to:
AreaRec = N * ( 5 / 12) = N * 0.416666
The following figures illustrates this trends:
The Sierpinski curve also share the very interesting property of the most fractals: its area converges rapidly to a finite limit while the total length of the segments that composed that curve have no limit.
All Variations described are available using Acheron 2.0
Born: 14 March 1882 in Warsaw, Poland
Died: 21 Oct 1969 in Warsaw, Poland
Waclaw Sierpinski attended school in Warsaw where his talent for mathematics was quickly spotted by his first mathematics teacher.
This was a period of Russian occupation of Poland and despite the difficulties, Sierpinski entered the Department of Mathematics and Physics of the University of Warsaw in 1899. The lectures at the University were all in Russian and the staff were entirely Russian. It is not surprising therefore that it would be the work of a Russian mathematician, one of his teachers Voronoy that first attracted Sierpinski.
In 1903 Sierpinski was awarded the gold medal for an essay on Voronoy's contribution to number theory.
Sierpinski graduated in 1904 and worked for a while as a school teacher of mathematics and physics in a girls school in Warsaw. However when the school closed because of a strike, Sierpinski decided to go to Krakóv to study for his doctorate. At the Jagiellonian University in Krakóv he attended lectures by Zaremba on mathematics, studying in addition astronomy and philosophy. He received his doctorate and was appointed to the University of Lvov in 1908.
When World War I began in 1914, Sierpinski and his family happened to be in Russia. When World War I ended in 1918, Sierpinski returned to Lvov. However shortly after taking up his appointment again in Lvov he was offered a post at the University of Warsaw which he accepted. In 1919 he was promoted to professor at Warsaw and he spent the rest of his life there.
Sierpinski was the author of the incredible number of 724 papers and 50 books. He retired in 1960 as professor at the University of Warsaw but he continued to give a seminar on the theory of numbers at the Polish Academy of Sciences up to 1967.
He was awarded honorary degrees from the universities Lvov (1929), St Marks of Lima (1930), Amsterdam (1931), Tarta (1931), Sofia (1939), Prague (1947), Wroclaw (1947), Lucknow (1949), and Lomonosov of Moscow (1967).
He was elected to the Geographic Society of Lima (1931), the Royal Scientific Society of Ličge (1934), the Bulgarian Academy of Sciences (1936), the national Academy of Lima (1939), the Royal Society of Sciences of Naples (1939), the Accademia dei Lincei of Rome (1947), the German Academy of Science (1950), the American Academy of Sciences 1959), the Paris Academy (1960), the Royal Dutch Academy (1961), the Academy of Science of Brussels (1961), the London Mathematical Society (1964), the Romanian Academy (1965) and the Papal Academy of Sciences (1967). | <urn:uuid:e43270a5-6cf7-434e-8569-3982dde47cfa> | 2.984375 | 1,720 | Tutorial | Science & Tech. | 42.437289 | 95,550,636 |
+44 1803 865913
It is well known, that the Sun as central star of our solar system gravitationally controls the orbits of planets and minor bodies. Much less known is the domain of plasma fields and charged particles, however, in which the Sun with a radius of less than 0.7 Million km governs the heliosphere out to about 15 Billion km, a distance about 20 000 times larger in radius or nearly 1013 times bigger in volume. What forces activates the Sun to maintain this power? Coronal Mass Ejections (CMEs) and their descendants are the troops serving the Sun during high solar activity periods.
This volume offers a comprehensive and integrated overview of our present knowledge and understanding of Coronal Mass Ejections (CMEs) and their descendants, Interplanetary CMEs (ICMEs). It results from a series of workshops held between 2000 and 2004. An international team of about sixty experimenters involved e.g. in the SOHO, ULYSSES, VOYAGER, PIONEER, HELIOS, WIND, IMP, and ACE missions, ground observers, and theoreticians worked jointly on interpreting the observations and developing new models for CME initiations, development, and interplanetary propagation.
The book is intended to provide scientists active in space physics research a with an up-to-date status of the current understanding of CMEs and ICMEs and their effects in the heliosphere, and also to serve the advanced graduate student with introductory material on this active field of research.
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Many of the theoretical problems encountered in seismology do not permit a simple and easily understood type of solution directly in terms of rays as given in the previous chapter. This is because certain constraints, or boundary conditions, are imposed on the propagation. This, then, involves interference effects from multiple reflections and refractions and conversion effects from P to SV, or vice versa, which at a distance from the source determine the characteristics of the propagation. We arrive at normal mode effects, that is, preferred modes of vibration for the system and at wave guide effects, that is, propagation constrained for certain frequencies and incident angles to a given layer by the boundary conditions imposed by the upper and lower surfaces of the layer.
KeywordsFree Surface Surface Wave Phase Velocity Group Velocity Rayleigh Wave
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Turn on thread page Beta
First order ordinary differential equation help please! watch
- Thread Starter
- 24-03-2011 09:48
- 24-03-2011 09:56
It's all correct until you started integrating - you can't take out variables from the integrals like that. The idea of the integrating factor is that you can get it into a form where you can integrate it by inspection, since it is in the form v du/dx + u dv/dx, which is the product rule for differentiation. If you compare x³ dy/dx + 3x²y with that form, can you see what it must integrate to?
(Original post by Chemhistorian)
- 24-03-2011 15:04
This is the first time ie used integrating factors and I am close to the solution gien..heres my working:
You can not integrate pointwise, but now you can write the equation as
using the product rule for differentiation.
This form is why you use integration factor, I think.
(the equation may be solved another ways, too).
Multiplying by dx you get differential of
and integrating this gives the solution
Last edited by ztibor; 24-03-2011 at 15:12.
- 24-03-2011 16:13
Just to add to that - the integrating factor method is obtained from the assumption that the left hand side can be written as a derivative of a product, and from this assumption the factor e^integral of P dx is obtained. Because of that, whenever you multiply a first order ordinary differential equation by the integrating factor, the left hand side will always be in the form of a derivative of a product. | <urn:uuid:6e1b8506-5d10-4692-8216-e50602a23cfc> | 2.53125 | 357 | Comment Section | Science & Tech. | 62.424167 | 95,550,658 |
Over the past 60 years, Alaska has warmed more than twice as rapidly as the rest of the United States. Source: National Climate Assessment Report 2014
Figure 34.25: Potential Effects of Climate Change ...
Scientists Agree: Global Warming is Happening and Humans are the Primary Cause
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abb1. Fig. 1 Observed impacts of climate change during the period since publication of the IPCC Fourth Assessment ...
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storms is also attributed in part to climate change by some experts #globalwarming #climatechange #COP21 #Paris – More at http://www.GlobeTransformer.org .
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Figure 1: Total amount of heat from global warming that has accumulated in Earth's climate system from 1962 to 2008, from Church et al. (2011).
Graphic: consequences of climate change
The projected impacts of Climate Change are depicted below, (adapted from Stern, N. 2006):
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The Effects and Consequences of Global Warming
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The Missouri River encroaches on homes in Sioux City, Iowa, during a 2011 flood Stocktrek Images/Media Bakery
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Figure 1: The global Nonhydrostatic ICosahedral Atmospheric Model, when run with a 0.87-kilometer grid size, simulates realistic features of major weather ...
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Global warming is cumulative and irreversible on a time scale of centuries. 47. | <urn:uuid:0d62a029-3726-4669-9c8f-9d76017b10ea> | 3.53125 | 1,316 | Content Listing | Science & Tech. | 41.036619 | 95,550,660 |
Please consider recommending that your university or department librarian order this book. This 5th edition contains all the things that made the earlier editions different from other introduction to differential geometry pdf. A new way of introducing differential forms and the exterior derivative. We included a detailed proof of the singular value decomposition, and show how it applies to facial recognition: “how does Facebook apply names to pictures?
This article is about co-ordinate geometry. In classical mathematics, analytic geometry, also known as coordinate geometry or Cartesian geometry, is the study of geometry using a coordinate system. Analytic geometry is widely used in physics and engineering, and also in aviation, rocketry, space science, and spaceflight. The Greek mathematician Menaechmus solved problems and proved theorems by using a method that had a strong resemblance to the use of coordinates and it has sometimes been maintained that he had introduced analytic geometry. Analytic geometry was independently invented by René Descartes and Pierre de Fermat, although Descartes is sometimes given sole credit.
Pierre de Fermat also pioneered the development of analytic geometry. Paris in 1637, just prior to the publication of Descartes’ Discourse. Illustration of a Cartesian coordinate plane. In analytic geometry, the plane is given a coordinate system, by which every point has a pair of real number coordinates.
Periodically Forced ODE’s – all of these disciplines are concerned with the properties of differential equations of various types. And a y, not to be confused with Difference equation. Geometric Methods and Applications – the motion of a body is described by its position and velocity as the time value varies. Extending the function, and air resistance may be modeled as proportional to the ball’s velocity. Basic facts in geometry, independent of the starting point.
Axis and the angle θ its projection on the xy, these classes of differential equations can help inform the choice of approach to a solution. Mostly concerned with their solutions, and the relationship involves values of the unknown function or functions and values at nearby coordinates. The solution may not be unique. He solves these examples and others using infinite series and discusses the non, many fundamental laws of physics and chemistry can be formulated as differential equations. Axioms for Euclidean Geometry — linear differential equations are the differential equations that are linear in the unknown function and its derivatives. Plane Symmetries or Isometries, lagrange solved this problem in 1755 and sent the solution to Euler. Also known as coordinate geometry or Cartesian geometry – elementary Projective Geometry.
Or quadric surface; a single equation corresponds to a curve on the plane. Order and degree of a differential equation, this only helps us with first order initial value problems. These definitions are designed to be consistent with the underlying Euclidean geometry. Additiones ad ea, as well as its esthetic aspects. | <urn:uuid:c2f776b5-7be6-4dde-b4ac-5597ef1b14cc> | 3.6875 | 596 | Truncated | Science & Tech. | 23.745373 | 95,550,662 |
XML Syntax Rules
The syntax rules of XML are very simple and logical. The rules are easy to learn, and easy to use.
XML Documents Must Have a Root Element
XML documents must contain one root element that is the parent of all other elements:
In this example <note> is the root element:
<body>Don't forget me this weekend!</body>
The XML Prolog
This line is called the XML prolog:
The XML prolog is optional. If it exists, it must come first in the document.
XML documents can contain international characters, like Norwegian øæå or French êèé.
To avoid errors, you should specify the encoding used, or save your XML files as UTF-8.
UTF-8 is the default character encoding for XML documents.
Character encoding can be studied in our Character Set Tutorial.
All XML Elements Must Have a Closing Tag
In HTML, some elements might work well, even with a missing closing tag:
In XML, it is illegal to omit the closing tag. All elements must have a closing tag:
XML Tags are Case Sensitive
XML tags are case sensitive. The tag <Letter> is different from the tag <letter>.
Opening and closing tags must be written with the same case:
<message>This is correct</message>
"Opening and closing tags" are often referred to as "Start and end tags". Use whatever you prefer. It is exactly the same thing.
XML Elements Must be Properly Nested
In HTML, you might see improperly nested elements:
In XML, all elements must be properly nested within each other:
In the example above, "Properly nested" simply means that since the <i> element is opened inside the <b> element, it must be closed inside the <b> element.
XML Attribute Values Must be Quoted
XML elements can have attributes in name/value pairs just like in HTML.
In XML, the attribute values must always be quoted.
The error in the first document is that the date attribute in the note element is not quoted.
Some characters have a special meaning in XML.
If you place a character like "<" inside an XML element, it will generate an error because the parser interprets it as the start of a new element.
This will generate an XML error:
To avoid this error, replace the "<" character with an entity reference:
There are 5 pre-defined entity references in XML:
Comments in XML
The syntax for writing comments in XML is similar to that of HTML.
<!-- This is a comment -->
Two dashes in the middle of a comment are not allowed.
Strange, but allowed:
White-space is Preserved in XML
XML does not truncate multiple white-spaces (HTML truncates multiple white-spaces to one single white-space):
XML Stores New Line as LF
Windows applications store a new line as: carriage return and line feed (CR+LF).
Unix and Mac OSX uses LF.
Old Mac systems uses CR.
XML stores a new line as LF.
Well Formed XML
XML documents that conform to the syntax rules above are said to be "Well Formed" XML documents. | <urn:uuid:0c7acd88-8f55-493b-a30e-851a936bb95c> | 4.25 | 695 | Documentation | Software Dev. | 57.988119 | 95,550,663 |
Members of the Roseobacter lineage of bacteria are prevalent in diverse marine environments where they carry out critical biogeochemical processes. Recent reports, based primarily on culture-independent studies and reviewed here, provide compelling evidence that members of this abundant lineage are involved in hydrocarbon degradation in natural systems. To determine whether cultured representatives possess similar catabolic capabilities, 24 representative Roseobacter genome sequences were searched for genes sharing homology with those known to be involved in the degradation of hydrocarbons and related compounds. Five distinct pathways for the aerobic degradation of aromatic compounds were identified in the genome collection, as were genes encoding alkane hydroxylases and uncharacterized ring-cleaving and -hydroxylating dioxygenases. Taken together, these findings suggest Roseobacters, a group historically overlooked with regard to this physiology, may play important roles in thedegradation of hydrocarbons at both naturally occurring and elevated levels in marine environments.
Mendeley saves you time finding and organizing research
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Have researchers found the seat of urination control in a primitive brain region? | <urn:uuid:5a36b7d3-574c-4e65-bdc5-486feba733b1> | 2.625 | 417 | Content Listing | Science & Tech. | 37.30251 | 95,550,673 |
Everything flows downstream
Research projects will show what’s entering Prairie watersheds, and the role of nature in protecting water quality
“Like kids and puddles – I have an unbreakable attraction to aquatic ecosystems,” says Pascal Badiou, a research scientist with DUC’s Institute for Wetland and Waterfowl Research.
For more than a decade, Badiou’s expertise in water – and more specifically, what’s in the water – has been nurtured on the rich landscape of the Prairies. This spring, his research team will complete their third and final year of monitoring at Camrose Creek in Alberta’s parkland region. Their findings will be compared with recent research at Broughton’s Creek in Manitoba and Smith Creek in Saskatchewan.
“Canadian Prairie wetlands are the single most understudied aquatic ecosystem in the world,” says Badiou. “Our previous work has shown that wetlands are great at dealing with contaminants. We need to continue to quantify just how important these systems are for regulating the quality and quantity of our water.”
The research at Camrose Creek was challenging in the first two years. Minimal snowpack meant there was little water running off the land. A more significant snowpack this year will give the team their best opportunity to monitor water headed downstream.
What’s in the Water
Existing research shows that wetlands help improve water quality by removing pollutants contained in run-off. These are broken down, consumed and stored within wetland vegetation and sediment, sending cleaner water downstream.
“Wetlands in cropland generally have high levels of nitrogen, phosphorus and pesticides, relative to wetlands in grasslands and pastures,” says Badiou. “This demonstrates the importance of keeping those wetlands on the landscape, in terms of mitigating pollution from cropland.”
As contaminant levels increase, communities can experience other water quality concerns, too.
“We know that wetland drainage increases the amount of nutrients sent downstream. That has the potential to cause other water quality issues. Think of the algae blooms we see in Lake Winnipeg, Lake Diefenbaker and Pigeon Lake,” says Badiou. “It’s happening all across the Prairies.”
Linking the Science
By researching these small watersheds, Badiou aims to better demonstrate what happens when people make changes to the Prairie’s natural systems, such as draining wetlands. He says that by having data with touchpoints in all three provinces, science can better demonstrate the importance of wetlands to the entire region.
“Regardless of where you are in the larger watershed, wetland drainage can impact you,” he says.
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Habitat restoration project provides business and environmental benefits at Alberta cattle farm.
School field trips connect Alberta youngsters to nature. | <urn:uuid:d74cd124-b5a4-4903-9718-9268e7c68490> | 3.4375 | 612 | Truncated | Science & Tech. | 37.047209 | 95,550,677 |
A repository & source of cutting edge news about emerging terahertz technology, it's commercialization & innovations in THz devices, quality & process control, medical diagnostics, security, astronomy, communications, applications in graphene, metamaterials, CMOS, compressive sensing, 3d printing, and the Internet of Nanothings. NOTHING POSTED IS INVESTMENT ADVICE! REPOSTED COPYRIGHT IS FOR EDUCATIONAL USE.
What can we learn from measuring the temperature of space?
On a clear night, when we gaze at the skies we can look back in time. With an optical telescope, or sometimes even with just the naked eye, we see the pinpoints of light that we call stars. What is actually meeting our eyes is energy in the visible wavelength that has travelled across space (and time) from that star or planet to us.
But what about the wavelengths that we can’t see? That ‘invisible’ energy can also tell us much about the universe and its history, if we know how to look at it. Scientists at NUI Maynooth’s Department of Experimental Physics know how to look at it, and their research is helping to cast the universe in a new light.
Dr Créidhe O’Sullivan, Prof Anthony Murphy, Dr Marcin Gradziel and Dr Neil Trappe are designing instruments to detect wavelengths in a region that lies between visible and radio waves called the ‘terahertz’ band. “From an astronomy point of view the reason you would want to look there would be to see the cool universe,” says Dr O’Sullivan, who explains that, on average, the universe is a pretty chilly place.
“Initially,the Big Bang was very hot, but the universe has been expanding for nearly 14 billion years since then, cooling as it expands. It is now averaging just below 3 Kelvin, which is around -270 degrees Celsius, and that is ideal for our wavelength range.”
By detecting and mapping small regions of variation in temperature, scientists can pick up signatures from the formation of planets and galaxies. Dr. O’Sullivan is particularly interested in the ‘cosmic microwave background’, a massive burst of radiation that is thought to have been released around 380,000 years after the Big Bang. Analysing it allows scientists to peer back and glean more clues about the heady days of the early universe, she explains, and the terahertz band is a good place to go looking.
Planck and Herschel go sky scanning
The European Space Agency satellites Planck and Herschel travelled into space to record the signals in this wavelength band, and NUI Maynooth scientists made important contributions to the design of the onboard instruments. “You are trying to look at something that is only 3 Kelvin, but perhaps there are objects nearby like the Sun or a moon, and they interfere,”explains Dr O’Sullivan. “Also when you are designing the optics for this wavelength – the lenses and mirrors- you need to make approximations. Mathematically it is quite tricky.”
But the work is paying off – during their missions the space telescopes beamed back highly useful information about the cool universe. “Both satellites worked extremely well,” says Dr O’Sullivan, who particularly notes the temperature map of the universe built up by Planck. “It has done a really good job of looking at this temperature – you won’t get better than that.”
Planck also picked up tantalising patterns of light polarisation from the early universe. This is intriguing because such polarisation could offer evidence for the early universe inflating rapidly shortly after the Big Bang, which would fit theoretical models. The push is on now to search further for patterns of light polarisation.
One of the big ripples so far has come out of a project called BICEP2 from a telescope in Antarctica that picked up patterns from the early universe. It’s an exciting development, according to Dr O’Sullivan, and the NUI Maynooth scientists are already on the case to search for more clues. Some of those efforts are ground-based, such as QUBIC (Q&U Bolometric Interferometer for Cosmology), which will also analyse polarisation data collected by a telescope in the Antarctic.
“Our specific expertise is in the designing of the optics for these telescopes – the mirrors and the lenses and how to get the radiation onto a detector,” says Dr O’Sullivan. “It is not quite the same as optical, it is not quite the same as radio, and that is our niche – we tend to get invited into these projects because we can design the optics.”
The NUI Maynooth physicists also have their sights set on further space-based missions. They are designing instruments for SPICA (Space Infrared Telescope for Cosmology and Astrophysics), a collaboration between ESA and the Japanese space agency JAXA, and they are working on a European project called FISICA to design a spatial interferometer telescope that will pick up the fine detail of planetary formation around nearby stars.
“Much of what we work on is for long-term projects, particularly the satellite-based initiatives, they will take 10 or 15 years,” says Dr O’Sullivan. “But we have already been involved in projects that are changing the way we look at the universe, and likewise with the current projects, you know that when it does work, it is going to make huge advances in our understanding.”
Experimental Physics at NUI Maynooth
Maynooth has a long tradition of excellence in Experimental Physics. The inventor of the induction coil, Nicholas Callan, was Professor of Experimental Physics from 1826 to 1864. Callan’s work has been recognised by the Institute of Physics and the Institute of Electrical and Electronic Engineering. One of Callan’s most distinguished pupils, Gerald Molloy, did pioneering work in the development of wireless telegraphy. His international reputation in this field was such that Marconi came to Dublin to attend some of his lectures.
Currently, staff of the Experimental Physics Department are involved in a number of research areas, including Terahertz Space Optics, Far Infrared Astronomy, Cosmology, Fluid Dynamics, and Molecular and Atmospheric Physics. Graduates from the department have progressed to working at ESA, NASA, Caltech, Intel, Hewlett Packard, and the Jet Propulsion Laboratory in California, to name but a few.
To learn more about Experimental Physics at NUI Maynooth and to keep up-to-date with research, news and events, please click here. | <urn:uuid:977b9173-82a8-4b8d-b876-1f266fd4834a> | 3.6875 | 1,407 | News (Org.) | Science & Tech. | 36.128379 | 95,550,686 |
Researchers that you don't need a magnetic material to create spin current from insulators. This discovery has important implications for the field of spintronics and the development of high-speed, low-power electronics that use electron spin rather than charge to carry information.
The new technique makes it possible to synthesize 3D DNA origami structures that are also able to tolerate the low salt concentrations inside the body, which opens the way for completely new biological applications of DNA nanotechnology. The design process is also highly automated, which enables the creation of synthetic DNA nanostructures of remarkable complexity.
A recently published study gives a vivid example of unusual chemical reactivity found in the reactions with organogold complexes. Using the complex of modern physical methods joined with computational studies, the authors proposed reaction mechanism, where a molecule of acetic acid serves as a proton shuttle, transferring the hydrogen atom between the reaction centers.
Researchers have shown that both the carrier mobility and the carrier density of graphene can be measured in a spatially resolved and non-destructive way - providing 'maps' of the electronic properties critical for the successful use of graphene in photovoltaics, electronics, spintronics and optics - using terahertz radiation and doing away with the need to fabricate devices.
Keynote presentations on the third day of Graphene Week 2015 offered an eclectic mix of fundamental science and practical chemical engineering. Here we report briefly on each of the talks, beginning with an introduction to optoelectronics in 2D semiconductors and heterostructures, and concluding with an outline of a highly promising 'kitchen sink' approach to graphene production.
Engineers have developed a new approach to structuring the catalysts used in essential reactions in the chemical and energy fields. The advance offers a pathway for industries to wean themselves off of platinum, one of the scarcest metals in the earth's crust.
A new fabrication technique that produces platinum hollow nanocages with ultra-thin walls could dramatically reduce the amount of the costly metal needed to provide catalytic activity in such applications as fuel cells. | <urn:uuid:02835284-0d4e-43e5-a929-f526c9df9cfc> | 2.5625 | 429 | Content Listing | Science & Tech. | 11.521116 | 95,550,699 |
If single slit-diffracted white light is passed through a double slit, the central fringe is white. Is that because the waves of different wave lengths are travelling the same distance and aren't diffracted out into the spectrum? Either side of that, would you then have a spectrum fringe with only red and blue visible at the edges, with the other colours merged together in the centre? And then as you go further out, would the spectrum fringes be much wider, as the red light is spread out much greater than the blue light? And would you start seeing more definition of the other colours in the spectrum fringe between the red and the blue as the fringe spacing increased, because the different colours are being reinforced less?
If that's all correct, what would increasing the slit separation do?
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Fringe patterns with polychromatic light watch
- Thread Starter
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Definition of the noun absorbance
What does absorbance mean as a name of something?
noun - plural: absorbances
- (physics) a measure of the extent to which a substance transmits light or other electromagnetic radiation
Alternative definition of the noun absorbance
- [physics] A logarithmic measure of the amount of light that is absorbed when passing through a substance
Absorbance: In spectroscopy, the absorbance of a material is a logarithmic ratio of the amount of radiation falling upon a material to the amount of radiation transmitted through the material. Absorbance measurements are often carried out in analytical chemistry.
- also known as Optische dichtheid, Absorbans
Printed dictionaries and other books with definitions for Absorbance
Click on a title to look inside that book (if available):
by Milan Milosevic
However, absorbance is a derived quantity. In an experiment, two single-beam spectra are measured, one a reference and the other the sample spectrum. The two spectra are divided to yield the transmittance. Although the transmittance is ...
by David A. Vaccari, Peter F. Strom, James E. Alleman
Absorbance is the reduction in the transmission of light along the light path and may occur due to both dispersion and absorption of light.
Titanium Dioxide by Janusz Nowotny
Its strong UV light absorbance means that TiO2 is applied as a sunscreen blocker and it is even ...
Solar Energy (2015)
An Introduction by Michael E. Mackay
The absorbance is the key parameter in the performance of any solar powered device. It dictates the optical properties of materials used in solar devices and indicates how much radiation is absorbed within a given distance as it penetrates the ...
The Basics and Routine Techniques by Mary Louise Turgeon
Absorbance is the measure of light stopped or absorbed. Percent transmittance is the measure of light transmitted through the solution. (From Campbell JB, Campbell JM: Laboratory mathematics: medical and biological applications, ed 5, ...
by Joseph Sneddon, Terry L. Thiem, Yong-Ill Lee
Absorbance is a unitless number ...
by R S Khandpur
Absorbance is the property of a sample, whereas absorptivity is the property of a substance and is a constant. Mathematically, absorbance is related to percentage transmittance T by the expression: The relationship between energy absorption ...
Advanced Management Principles by Gregory E. Bell
Absorbance is the portion of irradiance striking an object that is absorbed by the object. Transmittance is the portion of irradiance striking an object that passes through the object. Morphological plant characteristics are those characteristics ...
Applied Superconductivity (2015)
Handbook on Devices and Applications by Paul Seidel
The total absorbance is a function of the interaction length . Sprengers et al. [ 28] reported about improved optical coupling in the near-IR spectral range by integrating an SNSPD device on top of a planar optical waveguide. The nanowires ...
by Theodore P. Williams, Anne B. Thistle
Axial absorbance plotted against retinal position for 10 locations each on the horizontal and vertical meridians. Axial absorbance is the absorbance at 500 nm wavelength per micrometer of section thickness through the ROS, multiplied by the ...
by John O'Connor, Brett A. Sexton
The resultant absorbance is the negative log of the ratio of the intensities of the measured to reference intensities. In a Fourier transform instrument the background is measured as a single beam and the measured spectrum ratioed to this ...
by John Kenkel
The unit of absorptivity depends on the units of these other parameters, since absorbance is a dimensionless quantity. When the concentration is in molarity and the path length is in centimeters, the units of absorptivity must be L/(mol cm).
The separateeffects of dissolved and particulate mattercan be seenin a plot of absorbance at 420 nm(not calibrated for Pt–Co) in eutrophic Lake 227 (Figure 6). The absorbance in a filtered sample remained relatively constant between late ...
by Paul C. Sadek
absorbance The mathematical representation for the loss of incident radiant energy intensity (e.g., ultraviolet, visible, infrared) as it passes through the sample is the absorbance, A: ...
Dictionary of Chemistry (2014)
by Andrew Hunt
absorbance shows how strongly a sample absorbs radiation. Absorbance measures the extent of absorption of electromagnetic radiation by a sample in a ...
by C.K. Shah
Absorbance * Absorbance It measures the amount of monochromatic light absorbed by the coloured end product. It is useful for the quantitative analysis of coloured com- pound-the histochemical preparation. It is expressed as logarithms of ...
by Zerong Wang, Uta Wille, Eusebio Juaristi
the apparent absorbance (also called attenuance) is recorded.
by Jack Cazes
Absorbance. Detection. in. Capillary. Electrophoresis. Acoustic Field-Flow Fractionation for Particle Separation Adhesion of Colloids on...
The CLOD of a typical peptide is about 1 jug/mL using absorbance detection at 200 nm. If 10 nL are ...
by Hiroyuki Ohshima
Plots of log( absorbance) versus log(wavelength) to the yellow...
by Pei-Show Juo
Absorbance (A) The measurement of the amount of light absorbed by a solution. It is mathematically defined ...
The Water Dictionary (2010)
A Comprehensive Reference of Water Terminology by Nancy E. McTigue, James M. Symons
Ultraviolet absorbance measurements are typically reported in units of re- ciprocal centimeters. See also spectroscopy; ultraviolet absorbance. spectral analysis of surface waves (SASW) A method for inspecting prestressed concrete cylinder ...
Online dictionaries and encyclopedias with entries for Absorbance
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Photo about Absorbance
Chlorophyll absorbance spectra
Taken from Nature's Palette: The Science of Plant Color by David Lee
Photo credit: dullhunk
Video about Absorbance
Video shows what absorbance means. A logarithmic measure of the amount of light that is absorbed when passing through a substance, the capacity of a ...
See also the pronunciation examples of Absorbance!
Scrabble value of A1B3S1O1R1B3A1N1C3E1
The value of this 10-letter word is 16 points, but it's not an accepted word in the Official Scrabble Players Dictionary.
Anagrams of ABSORBANCE
What do you get if you rearrange the letters?
See also the blanagrams of Absorbance!
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Go to the usage examples of Absorbance to see it in context! | <urn:uuid:8fcaa1d1-bd5e-45a1-9e16-c7c37f353ba4> | 3.15625 | 1,510 | Structured Data | Science & Tech. | 36.515372 | 95,550,708 |
Last year was the warmest on Earth since record keeping began in 1880, according to a National Climatic Data Center report.
In 2014, the average global temperature was 58.24°F (14.58°C), which was 1.24°F (0.69°C) above the 20th-century average.
That made for the highest average temperature recorded in 135 years, surpassing previous records set in 2005 and 2010 by 0.07°F (0.04°C), according to the report. The fourth warmest year was recorded in 1998.
Last year also saw the hottest December on record.
Nine of the 10 warmest years on record, including 2014, have occurred during the 21st century, the report noted.
The global annual temperature has increased at an average rate of 0.11°F (0.06°C) per decade since 1880, and at an average rate of 0.28°F (0.16°C) per decade since 1970. | <urn:uuid:da7b959e-4512-45f5-b826-fcef6fc23006> | 3.359375 | 207 | News Article | Science & Tech. | 86.207118 | 95,550,714 |
On Sunday, Aug. 18, Pewa was a tropical storm when it crossed the International Date Line and moved from the Central Pacific to the Northwestern Pacific Ocean. Pewa now falls under the forecast authority of the Joint Typhoon Warning Center.
NASA's Aqua satellite passed over Typhoon Pewa on Aug. 19 at 01:05 UTC after it strengthened into a typhoon in the northwestern Pacific Ocean. The image shows that Pewa developed a small eye.
Image Credit: NASA Goddard MODIS Rapid Response
On Aug. 18, infrared satellite data showed that thunderstorm development and convection had slightly weakened, but the system remained well-organized. Forecasters at the Joint Typhoon Warning Center or JTWC, expected the slight weakening to quickly reverse itself as conditions around the storm improved. The JTWC forecast that Pewa would become a typhoon on Aug. 19, and it did.
NASA's Aqua satellite passed over Typhoon Pewa on Aug. 19 at 01:05 UTC shortly after it strengthened into a typhoon in the northwestern Pacific Ocean. The Moderate Resolution Imaging Spectroradiometer instrument image showed that Pewa developed a small eye surrounded by strong thunderstorms.
On Monday, Aug. 19 at 0900 GMT/5 a.m. EDT, Typhoon Pewa had maximum sustained winds near 65 knots/75 mph/120 kph. It was centered near 13.9 north and 177.9 east, about 726 nautical miles east-southeast of Wake Island. Pewa was moving to the northwest at 8 knots/9.2 mph/15 kph.
Pewa is expected to continue to intensify as it moves northwest. The JTWC expects Pewa to pass far to the northeast of Wake Island on Aug. 21 and 22.Text credit: Rob Gutro
Rob Gutro | EurekAlert!
Scientists discover Earth's youngest banded iron formation in western China
12.07.2018 | University of Alberta
Drones survey African wildlife
11.07.2018 | Schweizerischer Nationalfonds SNF
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
13.07.2018 | Event News
12.07.2018 | Event News
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13.07.2018 | Life Sciences | <urn:uuid:4c21230a-b62b-4858-951d-3fcea5c1d542> | 3.203125 | 995 | Content Listing | Science & Tech. | 48.854717 | 95,550,768 |
Dr Martin Edvardsson, whose research is published in the journal Animal Behaviour (August 2007), studied the bruchid beetle Callosobruchus maculatus, a serious pest in warmer parts of the world. Some females were given unlimited access to water while others were not. All females were free to mate with males and the study found that thirsty females mated 40% more frequently than those with free access to water.
Female bruchid beetles can absorb the water in the seminal fluid through their reproductive tracts and need to mate less frequently the more water they take from each mating. This is to a male’s advantage because the longer the female goes without mating with another male, the greater his chance of successful fertilization. By transferring a large amount of water with the sperm, a male can help ensure his sperm has more time to fertilize the eggs without having to compete with the sperm from future matings. Dr Martin Edvardsson of the University of Exeter says: ‘The large ejaculates may have evolved because males can make it less beneficial for females to remate by providing them with a large amount of water.’
From morsels of food to less useful offerings like dried leaves or balls of silk, insects’ nuptial gifts are thought to perform the role of enticing a female to mate or investing in the resulting offspring. However, this study shows that males can also prevent females from mating with other males by giving them a valuable nuptial gift. Dr Edvardsson says: ‘This research offers an alternative theory on the function of ‘nuptial gifts’, which are an important part of insect courtship and mating.’
Dr Edvardsson argues that the trade-off between the costs and benefits of mating is essential to the mating behaviour of female bruchid beetles. The males have spines on their genitalia that puncture the females’ reproductive tract as they mate. Because of the damage this causes, females must carefully trade off the costs and benefits of mating, and limit the number of times they mate depending on their need for water and sperm.
Because there are always costs as well as benefits associated with mating, similar trade-offs are likely to be important in many species where males provide their mates with material resources. ‘The key thing’ says Dr Edvardsson ‘is that the resource provided by males is less beneficial to females the more of it they already have, like water or food for example.’
Though Dr Edvardsson believes these findings may be relevant to many other animal species, he does not think the study has any implications for our understanding of sexual behaviour in all other animals. He concludes: ‘This is unlikely to occur in say, mammals and birds, because it is impossible for a male to give a female a gift that would fulfill her needs for food or water for such a long period of time. Also, while many female insects can store live sperm inside for long periods of time, females of these species need relatively fresh sperm to fertilize their eggs.
Abigail Dixon | 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
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13.07.2018 | Materials Sciences
13.07.2018 | Life Sciences | <urn:uuid:490df055-f1c2-4188-a0e9-186638f99574> | 4.15625 | 1,277 | Content Listing | Science & Tech. | 41.095496 | 95,550,769 |
Modelling Earth’s climate to predict its future has assumed tremendous importance in the light of mankind’s influence on the atmosphere. The climate of our two neighbours is in stark contrast to that of our home planet, making data from ESA’s Venus Express and Mars Express invaluable to climate scientists.
Venus is a cloudy inferno whilst Mars is a frigid desert. As current concerns about global warming have now achieved widespread acceptance, pressure has increased on scientists to propose solutions.The key weapon in a climate scientist’s arsenal is the climate model, a computer programme that uses the equations of physics to investigate the way in which Earth’s atmosphere works. The programme helps predict how the atmosphere might change in the future.
The more scientists look at those equations, the more they realise just how complicated Earth’s climate system is. Grinspoon puts the predicament like this: “In fifty or a hundred years, we will know whether today’s climate models were right but if they are wrong, by then it will be too late.”
To help increase confidence in the computer models, Grinspoon believes that scientists should look at our neighbouring planets. “It seems that both Mars and Venus started out much more like Earth and then changed. They both hold priceless climate information for Earth,” says Grinspoon.The atmosphere of Venus is much thicker than Earth’s. Nevertheless, current climate models can reproduce its present temperature structure well. Now planetary scientists want to turn the clock back to understand why and how Venus changed from its former Earth-like conditions into the inferno of today.
“Water vapour is a powerful greenhouse gas and it caused the planet to heat-up even more. This is turn caused more water to evaporate and led to a powerful positive feedback response known as the runaway greenhouse effect,” says Grinspoon.
As Earth warms in response to manmade pollution, it risks the same fate. Reconstructing the climate of the past on Venus can give scientists a better understanding of how close our planet is to such a catastrophe. However, determining when Venus passed the point of no return is not easy. That’s where ESA’s Venus Express comes in.
The spacecraft is in orbit around Venus collecting data that will help unlock the planet’s past. Venus is losing gas from its atmosphere, so Venus Express is measuring the rate of this loss and the composition of the gas being lost. It also watches the movement of clouds in the planet’s atmosphere. This reveals the way Venus responds to the absorption of sunlight, because the energy from the Sun provides the power that allows the atmosphere to move.In addition, Venus Express is charting the amount and location of sulphur dioxide in the planet’s atmosphere. Sulphur dioxide is a greenhouse gas and is released by volcanoes on Venus.
Håkan Svedhem | 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
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13.07.2018 | Life Sciences | <urn:uuid:95c7d270-a706-4fc2-b4c2-69a2163b6044> | 4.4375 | 714 | Knowledge Article | Science & Tech. | 55.735871 | 95,550,770 |
The concept of "green energy" got a whole lot more literal last week, when scientists announced they'd successfully turned living roses into electronic circuits. That's right — cyborg flowers are now a thing.
Despite how it sounds, the aim isn't to create a race of leafy green borg that will one day rise up and enslave their human masters. Instead, think smart plants that can sense and display environmental changes, or crops whose growth can be regulated at the flick of a switch.
Or plant-based fuel cells that convert the photosynthetic sugars into electricity. The very first electronic plant, developed by researchers at Linköping University in Sweden and described this week in Science Advances, is a step toward any one of those applications and many more.
"As far as we know, there are no previously published research results regarding electronics produced in plants," said study lead study author Magnus Berggren in a statement. "No one's done this before."
Here's how it's done: first, the the researchers introduce a synthetic polymer called PEDOT-S into the rose through its stem. The plant sucks up the polymer using the same vascular system (xylem) that transports water. Once inside xylem channels, the polymer self-assembles into an "wire" that conducts electrical signals, while still allowing water and nutrients to move around. By connecting these wires with naturally-occurring electrolytes in the plant's tissue, the researchers are able to create an electrochemical transistor, as well as a digital logic gate, a basic component of computer systems.
The researchers also introduced a variant of PEDOT-S into the leaves, where it forms "pixels"; groups of electrochemical cells separated by leaf veins. When a voltage is applied, these pixels change colour like a display.
The first cyborg plant is the culmination of two decades of work — the researchers first tried to hack electronics into trees in the '90s, but funding fell through — and yet it seems we've only scratched the surface of what's possible with this technology.
"Now we can really start talking about 'power plants' — we can place sensors in plants and use the energy formed in the chlorophyll, produce green antennas, or produce new materials," Berggren said. "Everything occurs naturally, and we use the plants' own very advanced, unique systems."
[Read the full scientific paper at Science Advances]
Top image: Chris Sorge / Flickr | <urn:uuid:7553a9b5-c6e3-409f-a139-0e5d6836bbe2> | 3.71875 | 509 | News Article | Science & Tech. | 38.529345 | 95,550,783 |
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Expert discusses phosphorus at Great Lakes Symposium
TOLEDO - Researchers have been continuing to narrow down not only the primary chemical culprit leading to Lake Erie’s growing issue of harmful algal blooms, but also exactly how and when it causes the problem so efforts can better be made to combat it.
Laura Johnson studies the issue of dissolved phosphorus runoff as the Director of the National Center for Water Quality Research at Heidelberg University.
She was among a panel of experts at the Toledo Zoo’s first Great Lakes Symposium on Wednesday where she discussed her research.
Johnson noted that algal blooms are not new to Lake Erie, and have in fact been dealt with before and successfully managed.
In the 1970s, blooms developed due to urban and industrial point-source runoff. By the 1980s and in through the ‘90s, regulations on phosphorus effectively and steadily reduced the total load drained into the lake. However, in recent years the harmful algal blooms reappeared and were worse than ever.
Point sources are a single, identifiable sources of pollution, such as a drain pipe. Non-point sources cover a much wider area and are harder to attribute to single contributors.
“We said, ‘Ok well, it seems like we have a pretty good handle on these point sources of phosphorus,’” Johnson said. “But now the rest of the phosphorus is mostly the non-point sources, the stuff that comes from land runoff. So we should be concerned about that.”
What they found was, with the total load of phosphorus remaining relatively stable, the more precise cause of the problem went previously unseen: dissolved phosphorus.
Dissolved phosphorus, in contrast to the particulate form attached to sediment, is far more bioavailable for algae to feed on.
Comparing individual watersheds’ dissolved phosphorus discharge levels within the Western Lake Erie Basin showed that those with higher percentages or agricultural land were the larger contributors.
“We can look (at the data) and say this is clearly coming off of the land,” she said. “That’s why we point to that as a concern.”
Still, even with the pinpointing of dissolved phosphorus as a more significant factor, total annual measures of how much of it was being discharged into the lake were fairly consistent over the last five years.
It could not account for why a bloom spiked in 2011, then dropped considerably the next year. Johnson noted that both years had almost the same total load of dissolved phosphorus, 570 to 614.
Further study of the data found that the strongest indicator of spikes in dissolved phosphorus that could eventually lead to major blooms were significant rain events occurring from the months of March through July, when the concentrations of dissolved phosphorus are at their highest.
“It’s how dense that phosphorus is,” Johnson said. “It’s the concentration that really matters, rather than the load.”
Johnson also pointed to a study that found farms are only losing about 1 percent of the phosphorus put down and are using the recommended levels.
“It really points to that a lot of farms are leaking a little bit of phosphorus,” she said. “It gave us the idea that maybe it’s in the wrong place, rather than at the wrong amount.” | <urn:uuid:015d878c-fe71-4d15-9a61-a0539b3c6d38> | 3.015625 | 716 | News Article | Science & Tech. | 45.567667 | 95,550,787 |
The Hubble revelations are the latest finds in an ongoing probe of Hanny's Voorwerp (Hanny's Object in Dutch), named for Hanny van Arkel, the Dutch teacher who discovered the ghostly structure in 2007 while participating in the online Galaxy Zoo project.
Galaxy Zoo enlists the public to help classify more than a million galaxies catalogued in the Sloan Digital Sky Survey. The project has expanded to include the Hubble Zoo, in which the public is asked to assess tens of thousands of galaxies in deep imagery from the Hubble Space Telescope.
In the sharpest view yet of Hanny's Voorwerp, Hubble's Wide Field Camera 3 and Advanced Camera for Surveys have uncovered star birth in a region of the green object that faces the spiral galaxy IC 2497, located about 650 millionlight-years from Earth. Radio observations have shown an outflow of gas arising from the galaxy's core. The new Hubble images reveal that the galaxy's gas is interacting with a small region of Hanny's Voorwerp, which is collapsing and forming stars. The youngest stars are a couple of million years old.
"The star clusters are localized, confined to an area that is over a few thousand light-years wide," explains astronomer William Keel of the University of Alabama in Tuscaloosa, leader of the Hubble study. "The region may have been churning out stars for several million years. They are so dim that they have previously been lost in the brilliant light of the surrounding gas."
Recent X-ray observations have revealed why Hanny's Voorwerp caught the eye of astronomers. The galaxy's rambunctious core produced a quasar, a powerful light beacon powered by a black hole. The quasar shot a broad beam of light in Hanny's Voorwerp's direction, illuminating the gas cloud and making it a space oddity. Its bright green color is from glowing oxygen.
"We just missed catching the quasar, because it turned off no more than 200,000 years ago, so what we're seeing is the afterglow from the quasar," Keel says. "This implies that it might flicker on and off, which is typical of quasars, but we've never seen such a dramatic change happen so rapidly."
The quasar's outburst also may have cast a shadow on the blob. This feature gives the illusion of a gaping hole about 20,000 light-years wide in Hanny's Voorwerp. Hubble reveals sharp edges around the apparent opening, suggesting that an object close to the quasar may have blocked some of the light and projected a shadow on Hanny's Voorwerp. This phenomenon is similar to a fly on a movie projector lens casting a shadow on a movie screen.
Radio studies have revealed that Hanny's Voorwerp is not just an island gas cloud floating in space. The glowing blob is part of a long, twisting rope of gas, or tidal tail, about 300,000 light-years long that wraps around the galaxy. The only optically visible part of the rope is Hanny's Voorwerp. The illuminated object is so huge that it stretches from 44,000 light-years to 136,000 light-years from the galaxy's core.
The quasar, the outflow of gas that instigated the star birth, and the long, gaseous tidal tail point to a rough life for IC 2497.
"The evidence suggests that IC 2497 may have merged with another galaxy about a billion years ago," Keel explains. "The Hubble images show in exquisite detail that the spiral arms are twisted, so the galaxy hasn't completely settled down."
In Keel's scenario, the merger expelled the long streamer of gas from the galaxy and funneled gas and stars into the center, which fed the black hole. The engorged black hole then powered the quasar, which launched two cones of light. One light beam illuminated part of the tidal tail, now called Hanny's Voorwerp.
About a million years ago, shock waves produced glowing gas near the galaxy's core and blasted it outward. The glowing gas is seen only in Hubble images and spectra, Keel says. The outburst may have triggered star formation in Hanny's Voorwerp. Less than 200,000 years ago, the quasar dropped in brightness by 100 times or more, leaving an ordinary-looking core.
New images of the galaxy's dusty core from Hubble's Space Telescope Imaging Spectrograph show an expanding bubble of gas blown out of one side of the core, perhaps evidence of the sputtering quasar's final gasps. The expanding ring of gas is still too small for ground-based telescopes to detect."This quasar may have been active for a few million years, which perhaps indicates that quasars blink on and off on timescales of millions of years, not the 100 million years that theory had suggested," Keel says. He added that the
quasar could light up again if more material is dumped around the black hole.
Keel is presenting his results on Jan. 10, 2011, at the American Astronomical Society meeting in Seattle, Wash.
For images and more information about Hanny's Voorwerp and spiral galaxy IC 2497, visit:http://hubblesite.org/news/2011/01
Donna Weaver | Newswise Science News
What happens when we heat the atomic lattice of a magnet all of a sudden?
17.07.2018 | Forschungsverbund Berlin
Subaru Telescope helps pinpoint origin of ultra-high energy neutrino
16.07.2018 | National Institutes of Natural Sciences
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
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posted by Matt
When 0.500 moles of boron trichloride react with 1.20 moles hydrogen gas to produce elemental boron and hydrogen chloride gas, the actual yield of boron was 66.4 % of the theoretical yield. The mass of boron obtained was _____ g.
Please help I'm stuck on it.
2BCl3 + 3H2 ==> 2B + 6HCl
0.5 mol BCl2 will produce 0.5 mol B if you have all of the H2 needed.
1.20 mols H2 gas will produce 1.20 x (2 mol B/3 mols H2) = 1.20 x 2/3 = 0.8 mol B if you hadd all of the BCl3 needed.
Both answers can't be right; the correct answer in limiting reagent problems is ALWAYS the smaller value and the reagent producing that value is the limiting reagent. In this case the LR is BCl3 and H2 is the excess reagent so you can produce 0.5 mol B as the theoretical yield. 0.5 mols x atomic mass B = estimated 5 g B. The yield is only 66.4%; therefore, you can collect only estimated 5 x 0.664 = ? g B.
Can we use moles of HCl instead of B to calculate limiting reactant?
Yes. The limiting reagent will always produce the LEAST product (whichever one you choose) | <urn:uuid:4f43abdd-e07d-4176-acf7-418b978545e9> | 3.0625 | 315 | Q&A Forum | Science & Tech. | 101.323733 | 95,550,804 |
A UCSB physicist outlines how this unique phenomenon occurs in a condensed matter system
UC Santa Barbara physicist Tarun Grover has provided definitive mathematical evidence for supersymmetry in a condensed matter system. Sought after in the realm of subatomic particles by physicists for several decades, supersymmetry describes a unique relationship between particles.
“As yet, no one has found supersymmetry in our universe, including at the Large Hadron Collider (LHC),” said the associate specialist at UCSB’s Kavli Institute for Theoretical Physics (KITP). He is referring to the underground laboratory in Switzerland where the famous Higgs boson was identified in 2012.
“This is a fresh insight as to how supersymmetry arises in nature.” The findings of Grover’s research, conducted with colleagues Donna Sheng and Ashvin Vishwanath, appear in the current online edition of the journal Science.
The fundamental constituents of matter — electrons, quarks and their relatives — are fermions. The particles associated with fundamental forces are called bosons. Several decades ago, physicists hypothesized that every type of particle in the Standard Model of particle physics, a theory that captures the dynamics of known subatomic particles, has one or more superpartners — other types of particles that share many of the same properties but differ in a crucial way.
If a particle is a fermion, its superpartner is a boson, and if a particle is a boson, its superpartner is a fermion. This is supersymmetry, a postulated unique theoretical symmetry of space.
While the Standard Model governing the ordinary world is not supersymmetric, it is often theorized that the more “fundamental” theory relevant to very hot systems, such as those probed in high-energy particle accelerators like the LHC (or higher energy ones yet to be built), might exhibit supersymmetry. This has yet to be proved or disproved by accelerator experiments.
However, through their calculations, Grover and his co-authors show that supersymmetry emerges naturally in a topological superconductor. An example is helium-3, a light, nonradioactive isotope of helium with two protons and one neutron (common helium has two neutrons). When helium-3 is cooled to almost absolute zero (0 Kelvin), it becomes a liquid superconductor. As understood only recently, the boundary of its container features fermions.
“The reason these fermions exist is related to time-reversal symmetry, which is unrelated to supersymmetry,” said Grover. A video of an object tossed vertically up in the air is a good example of time-reversal symmetry. When the video is played back, it shows the object following the same parabolic trajectory through the air as it did when the video was played normally. “We wanted to see what would happen to these fermions when time-reversal symmetry was broken,” Grover explained.
The scientists theorized that the application of a specified amount of magnetic field to the surface of the container would break the time-reversal symmetry. This, in turn, would cause the fermions to disappear due to their interaction with bosons that already exist in the liquid helium-3. Grover and his coauthors found that right at the point when fermions are about to disappear, the fermions and the bosons behave as superpartners of each other, thus providing a condensed matter analog of supersymmetry.
According to physicists, if supersymmetry can be proved in high-energy experiments, it opens the door to answers that physicists have been seeking for years and may pave the way to analyze and even integrate different fundamental physics theories such as quantum field theory, string theory and Einstein’s relativity.
“Grover’s team shows that supersymmetry may be studied in low-energy experiments,” said physics professor Leon Balents, Grover’s colleague at KITP. “This would be amazing in its own right and could serve as an inexpensive tabletop model for what to look for at particle accelerators.”
“Our paper provides insight into how and in what systems supersymmetry may emerge in a very natural way,” Grover said. “Maybe it doesn’t exist in our actual universe, but there exist these condensed matter systems, such as topological superconductors, where supersymmetry can exist. This opens the window for experimentalists to go and test supersymmetry and its exciting consequences in real life.”
Contact Info:Julie Cohen firstname.lastname@example.org (805) 893-7220
Julie Cohen | EurekAlert!
What happens when we heat the atomic lattice of a magnet all of a sudden?
18.07.2018 | Forschungsverbund Berlin
Subaru Telescope helps pinpoint origin of ultra-high energy neutrino
16.07.2018 | National Institutes of Natural Sciences
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
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People always take the space for granted. In the end, it's just emptiness — the capacity for anything else. Time is also ticking continuously. But physicists are people, they always need something to complicate it. Regularly trying to combine their theory, they found that space and time merge into a system so complex that an ordinary person would not understand.
Albert Einstein understand what awaits us in November 1916. The year before he formulated the General theory of relativity according to which gravity is not a force that is distributed in space, but a property of space-time. When you throw the ball in the air, it flies in an arc and returns to the earth, because the Earth warps space-time around itself, so the track of the ball and the earth will cross again. In a letter to a friend Einstein considered the problem of merging General relativity with its offspring, the nascent theory of quantum mechanics. But his math skills are just not enough. "I tortured myself with this!", he wrote.
Einstein never came to this. Even today, the idea of creating a quantum theory of gravity seems extremely distant. Disputes hide an important truth: a competitive approach all as one say that the space is born somewhere deeper — and this idea breaks the established 2500 years of scientific and philosophical view of it.the
Normal magnet on the fridge perfectly illustrates the problem faced by physics. He can pin a piece of paper and to resist the gravitation of the whole Earth. Gravity is weaker than magnetism or other electric or nuclear forces. Whatever quantum effects it stood, they will be weaker. The only tangible proof that these processes actually happen, this motley picture of matter in the early Universe — which is thought to have been painted by the quantum fluctuations of the gravitational field.
Black holes are the best way to test quantum gravity. "This is the best that you can find for experimentation," says Ted Jacobson from the University of Maryland, College Park. He and other theorists studying black holes as a theoretical fulcrum. What happens when you take the equations that work perfectly in the laboratory, and placed in the most extreme situations imaginable? Not whether there will be some barely noticeable blemishes?
Regarding the General theory predicts that matter falling into a black hole of infinitely compressed as it approaches the center, the mathematical cul — de-SAC called the singularity. Theorists can't imagine the trajectory of an object outside the singularity; all lines converge in it. Even to talk about it, as problematic, because the very space-time that determines mestopolojenie singularity ceases to exist. Scientists hope that quantum theory may provide us with a microscope, which will allow us to consider this infinitely small point of infinite density and to understand what is going on with getting to her matter.
On the border of a black hole the matter is not so constrained, the gravity is weaker and, as far as we know, all laws of physics should work. And the more discouraging the fact that they don't work. A black hole is limited by the event horizon, point of no return: the substance emerging from the event horizon, will not return. The descent is irreversible. This is a problem because all the known laws of fundamental physics, including quantum mechanical, are reversible. At least in principle, in theory, you should be able to reverse the movement and restore all the particles that you have.
With a similar puzzle physics faced in the late 1800s, when mathematics was considered the "black body", idealized as a cavity filled with electromagnetic radiation. The theory of electromagnetism James Clerk Maxwell predicted that such an object will absorb all radiation that falls on it, and will never come into equilibrium with the surrounding matter. "He can absorb infinite amount of heat from a reservoir which is maintained at a constant temperature," explains Rafael Sorkin from the Institute for theoretical physics Perimeter in Ontario. From the thermal point of view, it will have a temperature of absolute zero. This conclusion is contradicted by observations of real black bodies (such as oven). Continuing work on the theory of max Planck, Einstein showed that the black body can reach thermal equilibrium, if the radiation energy will be supplied in discrete units, or quanta.
Theoretical Physicists for nearly half a century tried to reach these solutions for black holes. The late Stephen Hawking of Cambridge University have taken an important step in the mid-70s, applying quantum theory to the field of radiation around black holes and showed that they have nonzero temperature. Consequently, they can not only absorb but also emit energy. Although his analysis was screwed up black holes in the area of thermodynamics, it has also exacerbated the problem of irreversibility. The outgoing radiation is emitted at the border of a black hole and does not transfer information from the bowels. This random thermal energy. If you reverse the process and feed this energy to the black hole, nothing comes up: you just get more heat. And it is impossible to imagine that in a black hole is something left, just trapped, because as soon as the black hole emits radiation, it is reduced and, according to Hawking's analysis, in the enddisappears.
This problem is called the information paradox, as the black hole destroys the information about the trapped particles, which you could try to recover. If the physics of black holes is indeed irreversible, something must carry the information back and our concept of space-time may have to change to fit this fact.the
Heat is the random movement of microscopic particles, like gas molecules. Since black holes can heat up and cool down, it would be reasonable to assume that they consist of parts or, if in General, from the microscopic structure. And since a black hole is just empty space (according to General relativity falling into a black hole, the matter passes through the event horizon, not stopping), part of the black hole should be a piece of space itself. And under the deceptive simplicity of a flat empty space hides a huge complexity.
Even the theory that was supposed to save the traditional idea of space-time, came to the conclusion that something is hiding under that smooth surface. For example, in the late 1970-ies Steven Weinberg, now working at the University of Texas at Austin, tried to describe gravity as well as describe other forces of nature. And found that space-time is radically modified in its smallest scale.
Physics initially visualized the microscopic space as a mosaic of small pieces of space. If you increase them to the Planck scale, infinitely small size in 10-35 of a meter, scientists believe that it is possible to see something like a chess Board. But maybe not. On the one hand, such a network of lines, chess space, will prefer some other direction, creating an asymmetry that contradicts the special theory of relativity. For example, light of different colors will move at different speeds — as in a glass prism that splits light into its component colors. And although the manifestation on a small scale would be difficult to notice, violations of General relativity will be openly obvious.
The Thermodynamics of black holes puts into question the picture of the space in the form of simple mosaic. Measuring the thermal behavior of any system, you can count part of it, at least in principle. Discard a energy and look at the thermometer. If the mercury soared, the energy should apply to relatively few molecules. In fact, you measure the entropy of the system, which represents its microscopic complexity.
If you do this with ordinary matter, the number of molecules increases with the volume of the material. So, in any case, it should be: if you increase the radius of the beach ball 10 times inside it fit 1000 times more molecules. But if you increase the radius of a black hole 10 times the number of molecules in it will be multiplied by just 100 times. The number of molecules of which it is composed, must be proportional not to its volume and surface area. A black hole can appear three-dimensional, but behaves as a two dimensional object.
This strange effect is known as the holographic principle because it resembles a hologram that seems to us like a three-dimensional object, and on closer inspection, the image produced by the two-dimensional film. If the holographic principle takes into account the microscopic components of space and its content — what physics allow, though not all — to create space will not be enough simple pairing its tiny pieces.the
In recent years, scientists have realized that this all needs to be involved quantum entanglement. It is a deep property of quantum mechanics, an extremely powerful type of communication, it seems much more primitive space. For example, experimenters can create two particles flying in opposite directions. If they are confused, they will remain linked regardless of the distance separating them.
Traditionally, when people talked about "quantum" gravity, they mean quantum discreteness, quantum fluctuations, and all other quantum effects — but not quantum entanglement. Everything changed for black holes. Over the lifetime of the black hole fall in it entangled particles, but when the black hole evaporates completely, the partners outside of the black hole remain confusing — with nothing. "Hawking should have called it a problem of confusion," says Samir Mathur of Ohio state University.
Even in vacuum, where no particles of electromagnetic and other fields internally confusing. If you measure the field in two different places, your readings will fluctuate slightly, but remain in coordination. If you divide the area into two parts, these parts will be in correlation, and the degree of correlation will depend on the geometrical property that they have: the area of the interface. In 1995, Jacobson said that the involvement provides a link between the presence of matter and geometry of space-time — and thus could explain the law of gravity. "More confusion — gravity is weaker," he said.
Some approaches to quantum gravity — especially string theory — consider involvement as an important cornerstone. String theory the holographic principle applies not only to black holes, but the universe as a whole, providing a recipe to create space — or at least some part of it. The original two-dimensional space will serve as a boundary more extensivevolumetric space. And the confusion is to associate three-dimensional space in a single and continuous whole.
In 2009, mark van Raamsdonk from the University of British Columbia has provided an elegant explanation of this process. Suppose a field on the border of not confusing — they form a couple of systems out of correlation. They correspond to the two separate universes, between which there is no method of communication. When systems become entangled, formed like a tunnel, a wormhole, between universes and space ships can move between them. The higher the degree of entanglement, the less length of the wormhole. The universes merge into one and no longer two separate. "The emergence of a large space-time directly links the entanglement of these degrees of freedom in field theory," says van Raamsdonk. When we observe correlations in the electromagnetic and other fields, they are a remnant adhesion that binds the space together.
Many other features of the space, in addition to its connectivity, can also reflect confusion. Van Raamsdonk and Brian record layer, working at the University of Maryland, argues that the ubiquity of entanglement explains the universality of gravity — that it affects all objects and penetrates everywhere. As for black holes, Leonard Susskind and Juan Maldacena believe that the entanglement between the black hole and she emitted radiation creates a wormhole back into a black hole. Thus information is stored and the physics of a black hole is irreversible.
Although these ideas of string theory work only for specific geometries and rekonstruiruet only one dimension of space, some scientists are trying to explain the emergence of space from scratch.
In physics, and in General, in the natural Sciences, space and time are the basis for all theories. But we never notice the space-time directly. Rather, we derive its existence from our everyday experience. We assume that the most logical explanation of the phenomena that we see, is some mechanism that operates in space-time. But quantum gravity tells us that not all phenomena fit perfectly into this picture of the world. Physicists need to understand that is even deeper ins and outs of the space, the reverse side of a smooth mirror. If they succeed, we will finish the revolution begun more than a century ago by Einstein.
In a recently published work in Nature Sustainability group scientists concluded that the Earth can support, at best, only 7 billion people on the subsistence level (and in this June we had already 7.6 billion). Achieving "a high level of life satisf...
for the First time in history, scientists have found evidence that a radical change of a volcano in southern Japan were a direct result of the eruption of another volcano 22 kilometers away. Monitoring these two volcanoes, Aira, and Kirishima – showe...
Almost a year ago Antarctic glacier Larsen has created iceberg A-68, one of the largest blocks of ice from everyone that knows the story. Video made using satellite imagery, shows a split, separation and the subsequent journey of the iceberg in the l...
Scientists have discovered fossil remains of an unusually large "naked" sea creatures that lived in the oceans half a billion years ago. This creation belongs to a mysterious and confusing group of animals, known under the Latin n...
the Scientists made a scientific breakthrough that could open the door to a new method of production and source of nuclear fuel – the World ocean, which contains accumulated over a long time chemical. Check a special fiber that al...
a Message from the English giant of astrophysics Stephen Hawking sent to the nearest black hole during a solemn funeral in Westminster Abbey, which took place on Friday, June 15. A specially written composition with his famous syn... | <urn:uuid:5ccc7d55-7ec6-4d62-b0cf-8283761d81e8> | 3.359375 | 2,847 | Content Listing | Science & Tech. | 40.58601 | 95,550,844 |
We’ve been harnessing the sun’s power for as long as we can remember. Our predecessors reaped countless of benefits from the sun. In the Philippines, solar panels are becoming increasingly popular. Because of the advantages the sun constantly bestows upon us, sometimes it’s hard to remember that like all other things, the sun will also come to an end.
If you’re wondering what exactly is going to occur, then you’ve come at the right place.
What’s going to happen?
The sun is classified as a main sequence star. Main sequence stars have a lifespan of around ten billion years. We’re already halfway there—which means that in another five billion years, the sun will finally run out of fuel, expand substantially and transform into a red giant… and devour our planet.
The sun’s main source of fuel is hydrogen, which it unceasingly converts into helium. This process is called nuclear fusion. Unfortunately, the amount of hydrogen isn’t infinite.
Once the sun has depleted the hydrogen in its disposal, the sun’s core will become increasingly hot and dense. Additionally, the outer region of the sun will swell and swell—and eventually engulf Mercury, Venus, and perhaps Earth.
But hey, even if the sun doesn’t completely reach our planet, the high temperature will still be enough to completely set Earth ablaze.
By then, we’re already out of the picture.
All these sound insanely terrifying, don’t they?
However, there’s no use fretting about what’s going to happen to us. At that point, after all, we’re already goners.
Let me clarify: humans shouldn’t be worrying about the sun’s death because Earth will be doomed much earlier than that.
You’ve read it correctly.
We can only speculate about how the future will be like, but let’s hope that when the inevitable happens, technology will be so sophisticated that humans can already journey around the solar system so they can seek another dwelling.
Earth, after all, won’t be viable for life anymore.
Here’s what’s going to happen.
In a few billion years, before the sun wholly consumes its fuel, the sun will shine a lot more fiercely than it does today. Why? Because nuclear fusion reactions will occur at a much swifter rate—as a result of the imbalance between hydrogen and helium (the former is quickly running out, while the latter is beginning to accumulate).
This new situation will lead to the following:
- melting of the poles,
- boiling of our bodies of water, and
- the total loss of our planet’s atmosphere.
No existence will then be left on Earth because it will be too hot and parched for life to thrive—precisely like Venus.
We’ve been benefiting from the sun since time immemorial. In the Philippines, there’s solar panels, among other things. This is precisely why it’s easy to forget that like everything else on earth, the sun will also come to its demise. We may not be alive to witness its death, but it’s important to be aware of how the sun’s end will come about.
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NASA's Mars 2020 mission, which will look for signs of past life on Mars, will use smart methods originally developed to find the oldest life on Earth, according the mission's Deputy Project Scientist, Dr Ken Williford. The 2020 mission builds on the successes of prior rovers, to make coordinated measurements that could detect signs of ancient life - or biosignatures - in their original spatial context. These techniques, known as "spatially resolved biosignature analysis" derive from geochemical analysis of early life on Earth.
Speaking at the Goldschmidt conference in Paris where he is presenting the methods to be adopted, Dr Ken Williford (who is also Director of the Jet Propulsion Laboratory's Astrobiogeochemistry Laboratory) said:
"Previous missions to Mars have used a relatively broad brush - analyzing average chemistry over roughly the size of a postage stamp - to "follow the water" and seek ancient habitable environments. Mars 2020 takes the next natural step in its direct search for evidence of ancient microbial life, focusing measurements to the microbial scale and producing high-resolution maps over similarly postage stamp-sized analytical areas.
New scientific methods for searching for the most ancient evidence for life on Earth have led to a leap forward in capabilities for biosignature detection. Rather than using "bulk" geochemistry techniques that measure the average composition of a rock, Mars 2020 is developing new capabilities including X-ray fluorescence and Raman spectroscopy to map the elemental, mineral, and organic composition of rocks at high spatial resolution, with analytical spot sizes about the width of a human hair. Understanding the spatial distribution of chemical features preserved in ancient rocks is key to determining whether or not they were formed by life.
Beyond astrobiology, these new techniques enable exploration of the planet Mars at telescopic to microscopic scales - from a mountain to a grain of sand."
The instruments in development for Mars 2020 have roots in the search for the earliest signs of life on Earth, as well as life in extreme environments - deep underground, or in hydrothermal settings along ocean-floor ridges. When these methods have been applied on Earth they have enabled scientists to lower limits of detection or to better understand formerly ambiguous observations.
In addition, the Mars 2020 mission will use the knowledge gained from its scientific exploration to select and collect key samples that could one day be examined in laboratories back on Earth. Thirty to forty rock and sediment core samples, each about 15 grams, will be hermetically sealed in titanium tubes and deposited in a safe location on the surface of Mars for possible retrieval by a future mission.
"Mars 2020 represents a crucial first step towards a possible Mars sample return. Our objective is to collect a diverse set of samples from our landing site with the best potential to preserve records of the evolution of Mars - including the presence of life if it was there. We'll use our onboard instruments to provide the critical field context that future scientists would need to understand the measurements made back on Earth."
Dr Williford also discussed the three remaining candidate landing sites for the Mars 2020 mission. One site at Columbia Hills in Gusev crater, was visited previously by the Spirit rover and features silica deposits interpreted by some as analogous to hydrothermal springs known to be inhabited on Earth. The two other sites are located close together on the edge of Isidis Planitia, one of the largest (and oldest) impact craters in the Solar System. Northeast Syrtis features some of the oldest exposed Martian crust with evidence for alteration in the presence of liquid water that leads researchers to believe that this site could have hosted subsurface life. Jezero crater features an ancient river delta and a lake that could have been a prime location for life on early Mars.
"We've got some hard decisions in front of us," Williford said. "Because of the possibility of sample return, the selected site could have an outsized impact on the future of Mars science compared to a typical mission. We've been working hard to understand the scientific potential of the different sites and engaging the international scientific community for input on this consequential choice. The team is extremely excited about the opportunity to bring a powerful new payload to the surface of Mars and produce some spectacular results wherever we end up."
Commenting, Emmanuelle J Javaux, Full Professor, University of Liège, Belgium said;
"It is exciting that now Space agencies realize how studies of early Earth and early life evolution are relevant for the search for life beyond Earth. This NASA MARS 2020 approach of mapping the elemental, mineral, and organic composition of rocks at high spatial resolution with non-destructive techniques is now commonly used on Earth to provide unambiguous evidence for early life in its preserved nanoscale context. The European Space Agency's EXOMARS 2020 mission will also use this methodology".
A conceptual image of the Mars 2020 rover is available to journalists from the press office or the link in Notes.
Press Officer |
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
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20.07.2018 | Information Technology
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The eastern population of the North Pacific right whale (NPRW, Eubalaena japonica) is the most endangered stock of whales in the world, with an estimated population of only 30 individuals (Wade et al. 2011b). The extreme rarity of these whales is likely the result of extensive historical whaling in the 19th century (Scarff 2001), followed by large illegal catches by the USSR in the 1960s (Doroshenko 2000, Brownell et al. 2001, Clapham et al. 2004). Little is known about the distribution, movements, or habitat use of this population, but the scant existing data suggest that it now occupies a greatly reduced range compared to historical times, when right whales were widely distributed across the Gulf of Alaska (GOA) and Bering Sea (BS) (Shelden et al. 2005, Shelden and Clapham 2006). The vast majority of eastern NPRW records (and search effort) since 1979 have occurred in the southeastern BS (Shelden et al. 2005); there have been only four sightings of NPRWs in the GOA since 2004 (Wade et al. 2011a) and no photo-identification or genotype matches between BS and GOA whales have been made (Wade et al. 2011a).
Mendeley saves you time finding and organizing research
Choose a citation style from the tabs below | <urn:uuid:ff4513e9-dbcc-4e5e-b5fd-81fd3c9cd1ac> | 3.5 | 284 | Academic Writing | Science & Tech. | 49.914305 | 95,550,854 |
The British Council's science team believes more dialogue needs to be at city, rather than national, level. For example, London with 7.4 million people consumes more energy than Ireland and the same as Greece or Portugal.
The site will report on the top ten cities' responses to climate change.
Solutions and good practice can be communicated and shared between schools.
The site will feature a climate prediction computer simulation where variables such as energy and water consumption can be changed to see whether they result in a warmer or cooler climate. | <urn:uuid:0232fda4-3ffb-4c9b-815a-84796559aad0> | 2.59375 | 107 | News (Org.) | Science & Tech. | 41.915403 | 95,550,857 |
Something strange is happening with a now-banned chemical that eats away at Earth's protective ozone layer: Scientists say there's more of it—not less—going into the atmosphere and they don't know where it is coming from.
When a hole in the ozone formed over Antarctica, countries around the world in 1987 agreed to phase out several types of ozone-depleting chemicals called chlorofluorocarbons (CFCs). Production was banned, emissions fell and the hole slowly shrank.
But starting in 2013, emissions of the second most common kind started rising, according to a study in Wednesday's journal Nature . The chemical, called CFC11, was used for making foam, degreasing stains and for refrigeration.
"It's the most surprising and unexpected observation I've made in my 27 years" of measurements, said study lead author Stephen Montzka, a research chemist at the National Oceanic and Atmospheric Administration.
"Emissions today are about the same as it was nearly 20 years ago," he said.
Countries have reported close to zero production of the chemical since 2006 but the study found about 14,300 tons (13,000 metric tons) a year has been released since 2013. Some seeps out of foam and buildings and machines, but scientists say what they're seeing is much more than that.
Measurements from a dozen monitors around the world suggest the emissions are coming from somewhere around China, Mongolia and the Koreas, according to the study. The chemical can be a byproduct in other chemical manufacturing, but it is supposed to be captured and recycled.
Either someone's making the banned compound or it's sloppy byproducts that haven't been reported as required, Montzka said.
An outside expert, Ross Salawitch, an atmospheric scientist at the University of Maryland, is less diplomatic. He calls it "rogue production," adding that if it continues "the recovery of the ozone layer would be threatened."
High in the atmosphere, ozone shields Earth from ultraviolet rays that cause skin cancer, crop damage and other problems.
Nature removes 2 percent of the CFC11 out of the air each year, so concentrations of the chemical in the atmosphere are still falling, but at a slower rate because of the new emissions, Montzka said. The chemical stays in the air for about 50 years.
Explore further: Ozone recovery may be delayed by unregulated chemicals
More information: An unexpected and persistent increase in global emissions of ozone-depleting CFC-11, Nature (2018). DOI: 10.1038/s41586-018-0106-2 , www.nature.com/articles/s41586-018-0106-2
NOAA press release | <urn:uuid:086de4b6-5967-470e-989a-5134d42cd631> | 3.234375 | 563 | News Article | Science & Tech. | 47.549333 | 95,550,869 |
Jump to navigation Jump to search
- The process of conveying something.
- (physics) The transmission of heat in a fluid by the circulation of currents.
- (meteorology) The vertical movement of heat and moisture, especially by updrafts and downdrafts in an unstable air mass. The terms convection and thunderstorm are often used interchangeably, although thunderstorms are only one form of convection. Towering cumulus clouds are visible forms of convection.
process of conveying something
transmission of heat by the circulation of currents
vertical movement of heat and moisture
- “convection” in Douglas Harper, Online Etymology Dictionary, 2001–2018. | <urn:uuid:a824d92a-dbe9-4745-ab30-2097cd66242b> | 2.984375 | 147 | Structured Data | Science & Tech. | 28.933333 | 95,550,880 |
Global sea level rise is not cruising along at a steady 3 mm per year, it's accelerating a little every year, like a driver merging onto a highway, according to a powerful new assessment led by CIRES Fellow Steve Nerem. He and his colleagues harnessed 25 years of satellite data to calculate that the rate is increasing by about 0.08 mm/year every year—which could mean an annual rate of sea level rise of 10 mm/year, or even more, by 2100.
"This acceleration, driven mainly by accelerated melting in Greenland and Antarctica, has the potential to double the total sea level rise by 2100 as compared to projections that assume a constant rate—to more than 60 cm instead of about 30." said Nerem, who is also a professor of Aerospace Engineering Sciences at the University of Colorado Boulder. "And this is almost certainly a conservative estimate," he added. "Our extrapolation assumes that sea level continues to change in the future as it has over the last 25 years. Given the large changes we are seeing in the ice sheets today, that's not likely."
If the oceans continue to change at this pace, sea level will rise 65cm (26 inches) by 2100—enough to cause significant problems for coastal cities, according to the new assessment by Nerem and several colleagues from CU Boulder, the University of South Florida, NASA Goddard Space Flight Center, Old Dominion University, and the National Center for Atmospheric Research. The team, driven to understand and better predict Earth's response to a warming world, published their work today in the journal Proceedings of the National Academy of Sciences.
Rising concentrations of greenhouse gases in Earth's atmosphere increase the temperature of air and water, which causes sea level to rise in two ways. First, warmer water expands, and this "thermal expansion" of the oceans has contributed about half of the 7 cm of global mean sea level rise we've seen over the last 25 years, Nerem said. Second, melting land ice flows into the ocean, also increasing sea level across the globe.
These increases were measured using satellite altimeter measurements since 1992, including the U.S./European TOPEX/Poseidon, Jason-1, Jason-2, and Jason-3 satellite missions. But detecting acceleration is challenging, even in such a long record. Episodes like volcanic eruptions can create variability: the eruption of Mount Pinatubo in 1991 decreased global mean sea level just before the Topex/Poseidon satellite launch, for example. In addition, global sea level can fluctuate due to climate patterns such as El Niños and La Niñas (the opposing phases of the El Niño Southern Oscillation, or ENSO) which influence ocean temperature and global precipitation patterns.
So Nerem and his team used climate models to account for the volcanic effects and other datasets to determine the ENSO effects, ultimately uncovering the underlying sea-level rate and acceleration over the last quarter century. They also used data from the GRACE satellite gravity mission to determine that the acceleration is largely being driven by melting ice in Greenland and Antarctica.
The team also used tide gauge data to assess potential errors in the altimeter estimate. "The tide gauge measurements are essential for determining the uncertainty in the GMSL (global mean sea level) acceleration estimate," said co-author Gary Mitchum, USF College of Marine Science. "They provide the only assessments of the satellite instruments from the ground." Others have used tide gauge data to measure GMSL acceleration, but scientists have struggled to pull out other important details from tide-gauge data, such as changes in the last couple of decades due to more active ice sheet melt.
"This study highlights the important role that can be played by satellite records in validating climate model projections," said co-author John Fasullo, a climate scientist at the National Center for Atmospheric Research. "It also demonstrates the importance of climate models in interpreting satellite records, such as in our work where they allow us to estimate the background effects of the 1991 eruption of Mount Pinatubo on global sea level."
Although this research is impactful, the authors consider their findings to be just a first step. The 25-year record is just long enough to provide an initial detection of acceleration—the results will become more robust as the Jason-3 and subsequent altimetry satellites lengthen the time series.
Ultimately, the research is important because it provides a data-driven assessment of how sea level has been changing, and this assessment largely agrees with projections using independent methods. Future research will focus on refining the results in this study with longer time series, and extending the results to regional sea level, so they can better predict what will happen in your backyard.
Explore further: Volcanic eruption masked acceleration in sea level rise
R. S. Nerem el al., "Climate-change–driven accelerated sea-level rise detected in the altimeter era," PNAS (2018). www.pnas.org/cgi/doi/10.1073/pnas.1717312115 | <urn:uuid:c504ed68-a34d-4da1-bfc4-68c65a06cff0> | 3.640625 | 1,045 | News Article | Science & Tech. | 35.403061 | 95,550,898 |
In most cases, it's more appropriate to use MXML than ActionScript to define states. However, sometimes you want to define states dynamically (in which case, you must use ActionScript). One such example is when you want to define a multipage form based on data loaded at runtime. Creating the form dynamically is advantageous because you can change the form without recompiling and republishing the SWF. However, because form elements aren't known at compile time, you cannot use MXML to define the states.
The ActionScript used to work with states corresponds to the MXML. In the following sections, you'll learn about the ActionScript equivalents to the MXML you learned about earlier.
When defining states using ActionScript, you use the
mx.states.State class. You can use the constructor as part of a new statement to define a new
var stateA:State = new State( );
You can assign a name to a state using the
name property, in much the same way as you'd use the
name attribute of the
stateA.name = "exampleStateA";
And just as you can use the
basedOn attribute of the
<mx:State> tag to define state inheritance, you can use the
basedOn property of the
State class. The following code defines a new state that is based on the state constructed in the previous two code snippets. Note that the
basedOn property expects a string specifying the
name of the state upon which you want to base the new state; you cannot assign it a ... | <urn:uuid:70bc037f-8e0c-4b4b-a5d0-24ffbd147612> | 2.921875 | 321 | Documentation | Software Dev. | 50.201225 | 95,550,903 |
The search mission is another example of fruit flies executing complex behaviors with very little “computational” power, their brains having 100,000 neurons compared to house flies with 300,000 neurons and humans with 100 billion.
Floris van Breugel
Fruit flies use their antennae, the two pill shaped bumps sticking out from the front of the head, to detect odors.
Such computational efficiency is the envy of robot makers everywhere and of interest to neuroscientists wanting to know more about the brains of insects, animals and humans, according to Floris van Breugel, a UW post-doctoral researcher and lead author of a paper in the Feb. 3 issue of Current Biology. Michael Dickinson, UW professor of biology, is the paper’s co-author.
It’s the smell of fermentation that draws fruit flies, genus Drosophila, to your wine or the fruit ripening on the kitchen counter, the same smell that leads them to food in orchards and compost heaps outdoors.
If not already in your house when you pour your wine, fruit flies come calling from outside, following attractive odors through open doors and windows, being small enough to slip around the edges of screens if not simply passing through the openings in the mesh.
Fruit flies use their antennae to detect odors and it’s long been known they have a keen sense of smell. But odors travel in whiffs of scent, not steady streams, particularly outdoors in the wind. Nothing this detailed has ever been published about how free-flying fruit flies conduct successful searches, van Breugel said.
Using wind tunnel results, van Breugel and Dickinson described the reflexive surging upwind when an odor is detected and then the casting about when the whiff of scent is lost.
One surprise – and another example of how efficiently fruit flies use their neurons – was that in the presence of attractive odors, flies began using their eyes to look for roundish objects that might be fruit, van Breugel said. Without an attractive odor, flies ignore such objects.
“Because an odor plume can be so chaotic, just tracking the plume may or may not get them to the source of the smell,” he said. “So that’s when visual exploration starts to take over. They start to explore objects with visual contrast that could be the source of the odor. They land and if it’s not something to eat, they continue the search.” A glass of wine would be a contrasting shape, like fruit, that would merit their attention.
Flies, a dozen at a time, were observed trying to locate an attractive odor at one end of a 3-foot-long wind tunnel specially designed by Dickinson and his lab group. The tunnel generates a steady flow of air about the velocity of a light wind. Ten cameras collected more than 70 hours of flight data including 50,000 individual trajectories.
During the work, van Breugel wasn’t expecting to find evidence that flies would search for food visually. Then he noticed them exploring the floor of the wind tunnel, which had a checkerboard pattern, when odors were present but not in their absence. He devised an experiment without the checkerboard, but with a round shape on the floor and each of two walls. When an attractive odor was present, fruit flies explored around and landed on those shapes.
“Their senses interact in very sophisticated ways so what they smell literally influences what they see,” Dickinson said. “These interactions between vision and olfaction is part of the secret of how flies do so much with such tiny brains, they have clever ways to combine information from different senses.”
Modeling how insect brains function could be useful in developing efficient robots, indeed one of the funders of the research is the U.S. Air Force Office of Scientific Research.
“The study of behavior has often been very subjective, but we’re at the point where we can collect data with enough richness and information that we can come up with quantitative interpretations of what’s happening,” van Breugel said. For example, van Breugel and Dickinson modeled the behavior of flies as a simple algorithm of three reflexes: surging, casting and attraction to small visual features. An algorithm is a set of rules that precisely defines a sequence of operations whether in a brain or in a computer.
Using a computer simulation, the authors showed that this simple three-step algorithm could reliably guide a fruit fly to food without the need for a long range plan or mental map.
“As we quantify more of their behaviors in such detail, we could discover more efficient and robust algorithms for controlling robotic systems of all kinds,” van Breugel said.
“Although finding fruit flies in your wine or beer can be a bit annoying, I hope people will pause to admire the tenacity of these clever little creatures,” Dickinson said. “They are really just hungry animals looking for something to eat, and have no intention of ruining your happy hour.”
While working on this project in the Dickinson lab, van Breugel earned his doctorate from California Institute of Technology.
Other funding for the work came from the National Science Foundation, the Paul G. Allen Family Foundation and the Hertz Foundation.For more information:
Sandra Hines | EurekAlert!
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 | Power and Electrical Engineering
17.07.2018 | Life Sciences
16.07.2018 | Physics and Astronomy | <urn:uuid:e6412462-acd1-4e51-9669-eae229493704> | 3.734375 | 1,788 | Content Listing | Science & Tech. | 48.655048 | 95,550,914 |
Scientists have finally laid hands on the first member of a recalcitrant group of proteins called the Wnts two decades after their discovery. Important regulators of animal development, these proteins were suspected to have a role in keeping stem cells in their youthful, undifferentiated state - a suspicion that has proven correct, according to research carried out in two laboratories at Stanford University Medical Center. The ability to isolate Wnt proteins could help researchers grow some types of stem cells for use in bone marrow transplants or other therapies.
The gene coding for a protein usually reveals clues about how that protein will react in the lab and how best to isolate it from other molecules. The Wnts are unusual, however, because the way they behave in the lab differs from what the gene suggests. Roeland Nusse, PhD, professor of developmental biology at the School of Medicine and one of the first to isolate a Wnt (pronounced "wint") gene, reports how his lab members overcame these hurdles in the April 27 advance online edition of the journal Nature.
"We found that the protein is modified, explaining why it has been difficult to isolate," said Nusse, who is also an investigator at the Howard Hughes Medical Institute. Although the proteins structure suggests it should dissolve easily in water, Karl Willert, PhD, a postdoctoral fellow in Nusses lab, found that an attached fat molecule makes the protein shun water and prefer the company of detergents instead.
The secret sulfate code that lets the bad Tau in
16.07.2018 | American Society for Biochemistry and Molecular Biology
Colorectal cancer risk factors decrypted
13.07.2018 | Max-Planck-Institut für Stoffwechselforschung
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
13.07.2018 | Event News
13.07.2018 | Materials Sciences
13.07.2018 | Life Sciences | <urn:uuid:3d1f5e8b-b5e0-4563-94ff-5f5f130a7744> | 3.421875 | 935 | Content Listing | Science & Tech. | 39.538871 | 95,550,915 |
Cyanothemis simpsoni Ris, 1915
Type locality: Ka Yima, Kangama, Gigbema, Dumballa, Sierra Leone
The only species currently recognised in this genus. Please refer to the genus diagnosis and introduction for more information.
Mostly rivers, but also streams, in open areas in forest, but sometimes shaded by gallery forest. Usually with coarse detritus and often dead trunks and/or probably overhanging branches to trap floating organic material required for egg-laying. From 0 to 800 m above sea level, but possibly up to 1500.
Abdominal segment 2 (lateral view)
Head (dorsal view)
Map citation: Clausnitzer, V., K.-D.B. Dijkstra, R. Koch, J.-P. Boudot, W.R.T. Darwall, J. Kipping, B. Samraoui, M.J. Samways, J.P. Simaika & F. Suhling, 2012. Focus on African Freshwaters: hotspots of dragonfly diversity and conservation concern. Frontiers in Ecology and the Environment 10: 129-134.
- Ris, F. (1915). New dragonflies (Odonata) of the subfamily Libellulinae from Sierra Leone. Annals Magazine Natural History, 213-223. [PDF file]
- Schouteden, H. (1934). Annales Musee Congo belge Zoologie 3 Section 2, 3, 1-84. [PDF file]
Citation: Dijkstra, K.-D.B (editor). African Dragonflies and Damselflies Online. http://addo.adu.org.za/ [2018-07-18]. | <urn:uuid:382e56ea-8660-41d8-9070-a24ee3edafb2> | 2.796875 | 374 | Knowledge Article | Science & Tech. | 66.132572 | 95,550,927 |
Note however that it's not just about blocking vs. non-blocking. Even with blocking, channels are often considerably faster than streams. E.g. if I want to copy a file from one location to another using a FileInputStream and FileOutputStream, I need to read bytes from the InputStream into a byte buffer managed by the JVM, and then transfer those bytes to the OutputStream. Using two FileChannels though, I can basically tell the system to transfer bytes directly from one location to the other using native code and hardware, without the overhead of copying things in and out of JVM-managed memory. So it's worth looking into NIO any time your I/O is slow - even if you don't want to use non-blocking features.
No, NIO is not a replacement for the traditional I/O classes in java.io. It's an alternate approach using different abstractions and with different goals.
If the traditional I/O classes work for you, great, use them - they're not going away any time soon. But there are some things that only NIO can do and some things that NIO does better. The inverse is also true.
There are many tools in the box, use the one that's best for the job.
2.10 Are there any existing specifications that might be rendered obsolete, deprecated, or in need of revision as a result of this work?
We are not proposing to deprecate the current java.io APIs, but we do hope that most developers will eventually migrate to the new APIs.
The proposed parsing and formatting APIs will duplicate some of the functionality already provided by the java.text package. This duplication is acceptable because the new APIs are intended to be efficient and easy to use for common, simple situations, while the java.text APIs were designed for maximal generality and flexibility.
Scott: A scanf/printf-like feature was one of the things we intended to put into 1.4, but due mostly to time constraints we were not able to get it done. It's a highly-requested feature, so look for it in a future release. | <urn:uuid:b0d779c7-e76f-498d-abf9-bca495fff4f1> | 2.578125 | 441 | Comment Section | Software Dev. | 54.836154 | 95,550,928 |
Like rapidly flowing gases and liquids, magnetically confined plasmas in tokamaks and related fusion devices exhibit a high degree of turbulence, which can generally destroy the optimal conditions for producing fusion energy. In a deeply encouraging new result, scientists have experimentally confirmed that turbulence can actually limit its own ability to wreak havoc.
Theoretical picture of self-generated turbulence flows in a tokamak cross section
Computer simulations of turbulence in the DIII-D tokamak agree with recent DIII-D experiments. Color contours illustrate the highly elongated structure of turbulence in the electron density
Researchers at the DIII-D tokamak at General Atomics have discovered that turbulence generates its own flows that act as a self-regulating mechanism. These flows, which are predicted theoretically and have been observed in computer simulations, create a "shearing" or tearing action that destroys turbulent eddies, as indicated by the figure. Such flows are like the large-scale zonal jets and patterns seen in the atmospheres of Jupiter and other large planets.
These turbulent flows have been clearly observed in recent experiments at DIII-D by using a special imaging system. The imaging measurements are obtained at a rate of one million frames per second and have a spatial resolution of about 1 cm. Observing and identifying these unique turbulence flows experimentally, and comparing their characteristics with theory, is helping to advance researchers understanding of this complex and crucial phenomena taking place in high temperature fusion plasmas.
David Harris | EurekAlert!
What happens when we heat the atomic lattice of a magnet all of a sudden?
18.07.2018 | Forschungsverbund Berlin
Subaru Telescope helps pinpoint origin of ultra-high energy neutrino
16.07.2018 | National Institutes of Natural Sciences
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
19.07.2018 | Life Sciences
19.07.2018 | Earth Sciences
19.07.2018 | Social Sciences | <urn:uuid:5e7579af-97f1-4f78-8302-254f8fbb23d1> | 3.390625 | 950 | Content Listing | Science & Tech. | 32.725505 | 95,550,942 |
For a little java a few patterns pdf natural language from the Indonesian island of Java, see Javanese language. This article is about a programming language. For the software package downloaded from java.
Java is a general-purpose computer programming language that is concurrent, class-based, object-oriented, and specifically designed to have as few implementation dependencies as possible. Java code can run on all platforms that support Java without the need for recompilation. 1995 as a core component of Sun Microsystems’ Java platform. The original and reference implementation Java compilers, virtual machines, and class libraries were originally released by Sun under proprietary licenses. | <urn:uuid:e8967c5d-d80b-470b-961a-c4ec7ae3433d> | 2.515625 | 129 | Personal Blog | Software Dev. | 16.860769 | 95,550,959 |
A dual sensor device to estimate fluid flow velocity at diffuse hydrothermal vents
Tivey, Margaret K.
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Numerous attempts have been made over the last thirty years to estimate fluid flow rates at hydrothermal vents, either at the exit of black smoker chimneys or within diffuse flow areas. In this study, we combine two methods to accurately estimate fluid flow velocities at diffuse flow areas. While the first method uses a hot film anemometer that performs high frequency measurements, the second allows a relatively rapid assessment of fluid flow velocity through video imagery and provides in situ data to calibrate the sensor. Measurements of flow velocities on hydrothermal diffuse flow areas were obtained on the Mid-Atlantic Ridge (MAR). They range from 1.1 to 4.9 mm/sec., at the substratum level, in low temperature (4.5 to 16.4°C) diffuse flow areas from the Tour Eiffel sulfide edifice. A strong correlation was observed between fluid flow velocities and temperature, supporting the possible use of temperature as a proxy to estimate flow rates in diffuse flow areas where such a simple linear flow/temperature relation is shown to dominate.
Author Posting. © The Author(s), 2009. This is the author's version of the work. It is posted here by permission of Elsevier B.V. for personal use, not for redistribution. The definitive version was published in Deep Sea Research Part I: Oceanographic Research Papers 56 (2009): 2065-2074, doi:10.1016/j.dsr.2009.06.008.
Suggested CitationPreprint: Sarrazin, J., Rodier, P., Tivey, Margaret K., Singh, Hanumant, Schultz, A., Sarradin, Pierre-Marie, "A dual sensor device to estimate fluid flow velocity at diffuse hydrothermal vents", 2009-06-12, https://doi.org/10.1016/j.dsr.2009.06.008, https://hdl.handle.net/1912/3118
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Results from shipboard high-pressure incubations of diffuse flow vent fluids collected from the Crab Spa and Alvinella sites at East Pacific Rise during the AT26-10 expedition, Jan. 2014 (Microbial Communities at Deep-Sea Vents project) Foustoukos, Dionysis (Biological and Chemical Oceanography Data Management Office (BCO-DMO). Contact: email@example.com, 2017-02-13)This dataset includes results from shipboard high-pressure incubations of diffuse flow vent fluids collected from the Crab Spa (9.8398º N, 104.2913º W) and Alvinella (9.8398º N, 104.2915º W) sites at East Pacific Rise ... | <urn:uuid:16f5fa16-051a-42fb-8d84-1fdc36d4124d> | 2.578125 | 748 | Academic Writing | Science & Tech. | 53.562389 | 95,550,974 |
This enormous Greenland shark may be the oldest living vertebrate in the world, it has been claimed.
In fact, it is estimated to be up to 512-years-old (meaning it was born before Shakespeare).Hillary Clinton hints that Vladimir Putin played Donald Trump at crunch summit
Living in the icy waters of the Arctic, the giant creature was located by scientists.
By measuring its size, they suggested the shark could have been born as early as 1505… the year Martin Luther became a monk, and King Henry VIII called off his engagement with Catherine of Aragon.
The Greenland shark lives in -1C to 10C waters and can swim as deep as 7,200ft. It is said to weigh more than a tonne.
This particular shark was measured at 18ft in length, meaning it could be anywhere between 272 to 512-years-old.
How do they know? This particular species grows at a rate of 1cm a year.Girl, 15, jailed in Indonesia for having an abortion after brother, 18, raped her
According to The Sun, the shark’s potential age was revealed in a study in journal Science.
It was the oldest of 28 Greenland sharks to be analysed.
Greenland sharks have an estimated life span of 400 years, and usually spend their time swimming around looking for a mate. | <urn:uuid:c40ed474-dccd-49e2-833c-acd21bdc7aae> | 2.875 | 274 | News Article | Science & Tech. | 65.644346 | 95,550,976 |
Es wird jetzt wohl ein bischen Mars-Dreck her geschickt.http://www.nasa.gov/mission_pages/msl/news/msl20130220b.html
PASADENA, Calif. -- NASA's Mars rover Curiosity has relayed new images that confirm it has successfully obtained the first sample ever collected from the interior of a rock on another planet. No rover has ever drilled into a rock beyond Earth and collected a sample from its interior.
Transfer of the powdered-rock sample into an open scoop was visible for the first time in images received Wednesday at NASA's Jet Propulsion Laboratory in Pasadena, Calif.
"Seeing the powder from the drill in the scoop allows us to verify for the first time the drill collected a sample as it bore into the rock," said JPL's Scott McCloskey, drill systems engineer for Curiosity. "Many of us have been working toward this day for years. Getting final confirmation of successful drilling is incredibly gratifying. For the sampling team, this is the equivalent of the landing team going crazy after the successful touchdown."
The drill on Curiosity's robotic arm took in the powder as it bored a 2.5-inch (6.4-centimeter) hole into a target on flat Martian bedrock on Feb. 8. The rover team plans to have Curiosity sieve the sample and deliver portions of it to analytical instruments inside the rover.
The scoop now holding the precious sample is part of Curiosity's Collection and Handling for In-Situ Martian Rock Analysis (CHIMRA) device. During the next steps of processing, the powder will be enclosed inside CHIMRA and shaken once or twice over a sieve that screens out particles larger than 0.006 inch (150 microns) across.
Small portions of the sieved sample later will be delivered through inlet ports on top of the rover deck into the Chemistry and Mineralogy (CheMin) instrument and Sample Analysis at Mars (SAM) instrument.
In response to information gained during testing at JPL, the processing and delivery plan has been adjusted to reduce use of mechanical vibration. The 150-micron screen in one of the two test versions of CHIMRA became partially detached after extensive use, although it remained usable. The team has added precautions for use of Curiosity's sampling system while continuing to study the cause and ramifications of the separation.
The sample comes from a fine-grained, veiny sedimentary rock called "John Klein," named in memory of a Mars Science Laboratory deputy project manager who died in 2011. The rock was selected for the first sample drilling because it may hold evidence of wet environmental conditions long ago. The rover's laboratory analysis of the powder may provide information about those conditions.
NASA's Mars Science Laboratory Project is using the Curiosity rover with its 10 science instruments to investigate whether an area within Mars' Gale Crater ever has offered an environment favorable for microbial life. JPL, a division of the California Institute of Technology, Pasadena, manages the project for NASA's Science Mission Directorate in Washington.
An image of the drill's rock powder held in the scoop is online at: http://www.nasa.gov/mission_pages/msl/multimedia/pia16729.html
For more about the mission, visit: http://www.nasa.gov/msl
You can follow the mission on Facebook and Twitter at: http://www.facebook.com/marscuriosity
Guy Webster 818-354-6278
Jet Propulsion Laboratory, Pasadena, Calif.
Dwayne Brown 202-358-1726
NASA Headquarters, Washington | <urn:uuid:cb16293c-a958-49bd-8d74-335975612043> | 3 | 749 | News Article | Science & Tech. | 48.416407 | 95,550,979 |
Dating geochronology methods azdg dating muslim
Also, if radiocarbon ages are to be compared to calendar ages then detailed knowledge about the long-term production of C in the atmosphere is needed.
Optical dating, on the other hand, is used to determine the time elapsed since last exposure of quartz or feldspar grains (the two most common minerals on Earth) to sunlight or heat (Lian and Roberts 2006).
Amino acid racemization (or ) in fossils is interpreted in terms of relative ages.
If the reaction rate can be calibrated using an independently dated nearby site with similar thermal history, absolute dates can be inferred through calibration.
This study, led by Christina Neudorf and Olav Lian describes the luminescence characteristics of quartz and K-feldspar grains from coastal dune and beach deposits on Calvert Island. D., Schoene B., 2007, Derivation of isotope ratios, errors and error correlations for U-Pb geochronology using 205Pb-235U-(233U)-spike isotope dilution thermal ionization mass spectrometric data, 8, Q08006, doi: 10.1029/2006GC001492 pdf Schoene B., Bowring S. | <urn:uuid:ef412ecb-b3f9-4175-84a5-dbb3bc1440b8> | 2.890625 | 266 | Spam / Ads | Science & Tech. | 39.359558 | 95,550,982 |
Another addition to the Kinja "Space Habitats Week" and this one is an awesome one.
Should we spend the resources to repair (or try to repair) our own planet or should we pursue the task of finding another world (like Mars) that we can change to make it livable for us Humans?
Before we talk about terraforming another planet like Mars, we have to talk about Earth—and whether we should be spending our resources trying to save it, or moving on to another pale blue dot. It’s a grim debate that some scientists say it’s time to have.
We’ve been imagining how to create a new Earth as long as we’ve known that ours was dying.
In the late 1930s, a few scientists and engineers posited that variations in climate were caused by humans—or more specifically, human-built systems powered by fossil fuels. If you think climate change is a contentious issue today, be glad you weren’t around back then. Attempting to prove that humans were actually changing the planet was a long, fraught, road, as Spencer Weart explains in his 2011 book, The Discovery of Global Warming. “Hardly anyone imagined that human actions, so puny among the vast natural powers, could upset the balance that governed the whole,” he writes. “This view of Nature—suprahuman, benevolent, and inherently stable—lay deep in most human cultures.”
As the concept began to pick up steam—so to speak—a similar thread was developing in science fiction. In 1942, the author Jack Williamson published a story called Collision Orbit that used the term “terraforming” for what is widely believed to be the first time:
He had been the original claimant of Obania, forty years ago; and Drake was the young spatial engineer he employed to terraform the little rock, only two kilometers through—by sinking a shaft to its heart for the paragravity installation, generating oxygen and water from mineral oxides, releasing absorptive gases to trap the feeble heat of the far-off Sun.
It may be a coincidence that the idea of terraforming emerged into popular culture within a few years of the emergence of climate change science. But even so, it’s interesting that humans only imagined having the power to shape other planets after they realized they might be shaping their own—however unwittingly.
As On Earth So On Mars
The relationship between Earthly concerns and planetary engineering has only grown more complicated since those early years.
In the 1990s, NASA trained its focus on Mars, sending the Pathfinder mission to the surface of the Red Planet. At the same time, scientists were studying how Martian geology could be altered for humans. In 1993, a NASA scientist named Chris McKay and Robert M. Zubrin of Pioneer Aeronautics published a seminal paper called Technological Requirements for Terraforming Mars that laid out a series of methods that could be used to make Mars habitable.
All involved making Mars warmer and wetter by creating an atmosphere, but the technical methods differed wildly: One imagined using mirrors orbiting Mars to blast its polar ice caps with sunlight, melting the ice and releasing the trapped carbon dioxide, which in turn would warm up Mars and create rainfall. Another imagined “diverting” asteroids—which contain frozen ammonia, an important ingredient in life—to hit Mars’ surface repeatedly:
Forty such missions would double the nitrogen content of Mars’ atmosphere by direct importation, and could produce much more if some of the asteroids were targeted to hit beds of nitrates, which they would volatilize into nitrogen and oxygen upon impact. If one such mission were launched per year, within half a century or so most of Mars would have a temperate climate, and enough water would have been melted to cover a quarter of the planet with a layer of water 1 m deep.
McKay and Zubrin seemed fully aware of how far away their concepts might be, and they acknowledge that in their 1993 paper, saying that we shouldn’t expect true terraforming to happen anytime soon.
But they concluded their analysis with some interesting language: They talk about Earth.
Moreover, in the process of modifying Mars, they are certain to learn much more about how planets really function and evolve, enough perhaps to assure wise management for our native planet.
It seemed that even as these scientists were seriously analyzing our ability to shape another planet, they were looking in the rearview mirror—and wondering if anyone would fix our own.
Save or Escape?
The idea of terraforming has shifted in the time since—and increasingly, it focuses not on Mars or other planets, but Earth. This year McKay—one half of the duo behind the 1993 terraforming paper—gave a fascinating web chat about his work looking for “extremophiles,”or organisms that can survive in the most inhospitable places on Earth (think the Atacama desert or deep in Antarctic ice). This research could identify “candidate organisms” to populate Mars as its surface temperature increases.
There have been other major breakthroughs, too, like the discovery of nitrate and fluorine in rocks on Mars. In April, McKay was one of a group of authors on a paper describing the discovery of nitrate in Martian soil (thanks, Curiosity!), suggesting that this vital component of life could be used in the process of terraforming. Another discovery this year—of the gas fluorine—would lend itself towards creating a protective atmosphere.
Over email, McKay pointed out that the focus of terraforming research is returning to Earth. “Discussions of Geo-engineering on Earth have greatly increased,” he wrote, describing geo-engineering as “a cousin” to terraforming. “Think of it as terra-keeping,” he added. In 2010, he authored a chapter called Planetary Ecosynthesis on Mars and Geo-Engineering on Earth: Can We? Should We? Will We?, suggesting that “a habitable Mars is not a ‘lifeboat’ for the Earth, but it may provide deep and useful insights in the workings of biology and biospheres.”
In the paper, he points out something odd: What we’re talking about doing on Mars—warming it—is what we’ve already done on Earth. By seeing Mars as a mirror image of our own warming planet, the idea of radically geo-engineering Earth seems more attainable. “The thought of making Mars habitable by purposeful action opened up the path to thinking about keeping Earth habitable by planetary action,” he writes.
It’s true: Discussions about terraforming Earth, not Mars, are becoming more and more common. It’s almost as if the science of making Mars livable could actually inform repairing our own. In an essay called Terraforming Earth, the scifi author Kim Stanley Robinson—who described terraforming the Red Planet in his beloved Mars trilogy—argued that we should be thinking about using similar techniques to fix our own planet, like carbon capture and even shooting sulfur dioxide particles into the atmosphere to block the sun’s rays. “Geoengineering,” he writes, “has become our ongoing responsibility to life on this planet, including all human generations to come.”
The idea that we’ll “escape” Earth for Mars seems more and more outdated. The science of the thing is more complicated than that survivalist binary—creating a second Earth on Mars is too closely bound up with the original. By studying how we could create life on another planet, we’re also reckoning with how to save our own. | <urn:uuid:d41125c6-7d7c-46ee-a16e-5938acb5ef28> | 3.21875 | 1,608 | Personal Blog | Science & Tech. | 38.622382 | 95,550,986 |
But the female concave-eared torrent frog, Odorrana tormota, has a more direct method of declaring her interest: She emits a high-pitched chirp that to the human ear sounds like that of a bird.
This is one of several unusual frog-related findings reported this week in the journal Nature.
O. tormota lives in a noisy environment on the brushy edge of streams in the Huangshan Hot Springs, in central China, where waterfalls and rushing water create a steady din. The frog has a recessed eardrum, said Albert Feng, a professor of molecular and integrative physiology at the University of Illinois and team leader on the new study.
“In the world we know of only two species – the other one in Southeast Asia – that have the concave ear,” Feng said. “The others all have eardrums on the body surface.”
Earlier studies, conducted by Feng, Jun-Xian Shen at the Institute of Biophysics at the Chinese Academy of Sciences and Peter Narins at the University of California, Los Angeles, found that O. tormota males emit – and respond to – unusual chirping calls from other males. These calls are audible, but also have energy in the ultrasonic range. The recessed ear structure protects an eardrum that is 1/30 the thickness of that of a normal frog, allowing it to detect very high frequency sounds.The unusual ear structure and the high-pitched calls are likely an evolutionary adaptation to the noisy environment, Feng said. The waterfalls and streams produce a steady racket predominantly in a lower frequency range than that used by the frogs.
The frog calls are quite complex. A single O. tormota frog broadcasts its message over several frequencies at once, at harmonic intervals, like a chord strummed simultaneously on several strings.
The new analysis, conducted by Shen, Feng and Narins, found that female O. tormota frogs also emit a call that spans audible and ultrasonic frequencies. The team has not observed females vocalizing in the wild (the frogs are nocturnal and can leap up to 30 times their body length), but in laboratory settings the females emitted calls only when they were carrying eggs.
Male O. tormota frogs exposed to recorded female calls were quite responsive, usually chirping within a small fraction of a second.
“The frog’s response is instantaneous – right after the stimulus,” Feng said.
In the laboratory, the males usually chirped and then leapt directly at the source of the female call. Their ability to home in on the sound call was astonishingly precise, Feng said. A typical male could leap toward the sound with an accuracy of more than 99 percent.
“This is just unheard of in the frog kingdom,” he said.
Only elephants, humans, barn owls and dolphins are known to detect sound with similar precision. The small distance between the frog’s ears (about 1 centimeter) makes its ability to localize the sound that much more impressive, Feng said.
How the female picks a mate in the wild is still unknown, however.
“We have a lot of work to do to figure out whether she directs the signal to one male or whether she lets a bunch of males come and compete, or whether there is any kind of dueting session during which she then decides: ‘OK, You’re my guy. Hop on my back and I’ll take you to the creek!’ ” Feng said.
These studies likely have implications for human health. Earlier research into the mechanics of frog hearing and directional hearing helped Feng and his colleagues at the U. of I.’s Beckman Institute for Advanced Science and Technology design an “intelligent” hearing aid that boosts sound signals of interest embedded in other sounds in the immediate environment of the listener.
Diana Yates | University of Illinois
O2 stable hydrogenases for applications
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Scientists uncover the role of a protein in production & survival of myelin-forming cells
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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.
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The consequences of climate change for human security are profound, but much of the last decade has been lost in avoiding those consequences. The implications for human security are serious. Today, with the consequences of climate change being increasingly recognised by military analysts, there is a risk of the “securitising” of the climate change agenda leading simply to military responses rather than a more preventative course of a rapid shift to a low-carbon society.
A World Blowing Cold and Hot
In 2009-10, the United Kingdom and much of the rest of north-west Europe experienced one of the coldest and most prolonged winters for several decades. In the minds of many people this seemed to confirm the view that the evidence for global warming was limited at best, and that the views of climate change sceptics were to be taken seriously. Furthermore, the winter’s experience came after the Copenhagen climate negotiations made little progress, and was also in the aftermath of a major controversy concerning climate change research at the University of East Anglia in the UK.
In this context- of suspicion over the reality of climate change – many people in Western Europe found it difficult to believe that the month of January 2010 was actually one of the warmest on record. This was the case when expressed in global rather than European terms – while the north-east Atlantic had been experiencing severe cold, parts of North America had warmer than average winters, and temperatures were high in many other parts of the world.
As 2010 progressed, two other weather events and one oceanic development added further to a sense of uncertainty. For much of the mid-summer period, Russia experienced exceptionally high temperatures which, in the case of the greater Moscow region, resulted in numerous forest fires leading to smog over the city. At the same time, further south in Central Europe, there was widespread flooding across 8 countries. In addition to this, there were appalling floods in Pakistan as the monsoon season was marked by some of the heaviest rainfall in decades. The full scale of the losses in Pakistan is still not clear.
Few climate scientists sought to claim that these weather events were direct indicators of climate change, but an indirect connection was certainly suggested. While it may be a common mistake to confuse “short-term weather” with “long-term climate”, it has been widely predicted that as the atmosphere of the entire planet slowly heats up, then weather systems should be expected to become more energetic, leading to extremes of weather events such as intense tropical storms, exceptional monsoons or continental heat waves. The experiences in Russia and Pakistan could be no more than equivalent to some of the extreme events that have been witnessed in the past, but their conjuncture at least reminded many people of other aspects of climate change.
The final element for 2010 was not a weather event as such, but a report that the Artic Ocean was experiencing one of the most substantial losses of mid-year sea ice on record. What seemed particularly surprising was that this should be happening within a matter of months of such a severe winter in the north-east Atlantic. In fact, the loss of sea ice was within the predictions that climate change models have produced in recent years. The overall impact of the loss of sea ice and the extreme weather experienced in Russia and Pakistan meant that by early September there was a widespread sense, once again, that climate change should be taken seriously.
Climate Change in Context
The possible impact of increased carbon dioxide levels in the atmosphere was well recognised over 40 years ago, and by the end of the 1980s there was serious concern that there would be substantial changes in the planet’s climate if carbon emissions were not curbed. Although not directly related to climate change, the potential destruction of the ozone layer through the release of CFC pollutants was recognised in the mid-1980s as being the first clear example of human activity having an impact on the entire global ecosystem. The ozone problem was relatively easy to counter, since CFCs could be replaced, and phasing them out through the Montreal Convention was agreed in 1987. Partly because of the sudden and serious nature of the CFC issue, climate change research was attracting far more attention by 1990.
At the same time, there was one aspect that limited the extent of the concern. This was that studies of natural climate change in prehistoric times have indicated that most of the impact was in the north and south temperate latitudes. If this was repeated with human-induced climate change then at least the countries most likely to be affected would be wealthy enough to be able to adapt. With the tropics and sub-tropics buffered against excessive impacts, poorer people across the world might have less to contend with.
By the early 1990s, advances in climate change science showed that the pattern of natural climate change would not be repeated by human-induced change, and that those parts of the world least able to cope would be seriously affected. By the early part of the 2000s, further work was actually showing that there would be an asymmetric impact. In broad terms, large parts of Antarctica, the southern oceans and the southernmost parts of the continental land masses would experience the smallest increases in temperature, whereas the Arctic region and most northern, sub-tropical and tropical land masses would experience above-average increases. There were also indications that rainfall would tend to increase over the oceans and Polar Regions but decrease over the tropical and sub-tropical land masses.
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Molecular Dynamics of Slow Viscous Flows
We use molecular dynamics techniques to study the microscopic aspects of several slow viscous flows past a solid wall, where both fluid and wall have a molecular structure. Systems of several thousand molecules are found to exhibit reasonable continuum behavior, albeit with significant thermal fluctuations. In Couette and Poiseuille flow of liquids we find the no—slip boundary condition arises naturally as a consequence of molecular roughness, and that the velocity and stress fields agree with the solutions of the Stokes equations. At lower densities slip appears, which can be incorporated into a flow—independent slip—length boundary condition. An immiscible two—fluid system is simulated by a species—dependent intermolecular interaction. We observe a static meniscus whose contact angle agrees with simple estimates and, when motion occurs, velocity—dependent advancing and receding angles. The local velocity field near a moving contact line shows a breakdown of the no—slip condition.
KeywordsContact Angle Contact Line Poiseuille Flow Slip Length Slip Boundary Condition
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Separation of para and ortho water
Not all water is equal—at least not at the molecular level. There are two versions of the water molecule, para and ortho water, in which the spin states of the hydrogen nuclei are different. In the journal Angewandte Chemie, German researchers have now reported the successful separation of the two forms.
Spin is a quantum mechanical value that can be visualized as the intrinsic angular momentum of a particle rotating around its own axis. A hydrogen nucleus (proton) can adopt two different states, comparable to rotation clockwise and counterclockwise.
In the case of water, the nuclear spins of the two—indistinguishable—protons can be combined in four different ways: one antisymmetric and three symmetric wavefunctions. Water adopting the antisymmetric wavefunction is called para water, whereas water adopting one of the symmetric ones is called ortho water. Because switching from one state to the other is “forbidden” due to quantum-mechanical symmetry rules, the two spin isomers cannot interconvert without external influences such as collisions.
A team at the Center for Free Electron Laser Science (DESY and University of Hamburg) led by Jochen Küpper and Daniel Horke has now successfully separated the two spin isomers and prepared isolated, highly pure samples of para and ortho water.
The challenge was to “freeze” the spin states by diluting single water molecules to such an extent that they could no longer collide with each other. To achieve this, the researchers use a noble gas high-pressure chamber charged with one droplet of water. When the chamber’s pulse valve is opened, the mixture shoots into a vacuum chamber at supersonic speeds, cooling rapidly due to the extremely fast expansion. This results in a focused beam of very cold water molecules that are so far from each other that they cannot induce a spin flip in each other.
For the separation, the researchers made use of the fact that para and ortho water molecules do not have the same quantum states. In a strong inhomogeneous electric field, the accelerated water molecules are deflected from their flight path by a different amount depending on their quantum state.
Possible applications for spin-pure water extend to many fields. Astrophysicists have determined that the ratio of ortho water to para water in interstellar ice is different from what is expected. Spin-pure water could enable revealing laboratory experiments. Techniques such as nuclear magnetic resonance spectroscopy (NMR) could benefit as their sensitivity could be increased by the use of para water in the hydration shells of proteins, improving the determination of their structure.
About the Author
Dr. Jochen Küpper is a team leader at DESY and Professor of Experimental Physics at the University of Hamburg. His research field comprises molecular physics and physical chemistry, focusing on the interconnection of structure, dynamics, and function of molecules. He already received several awards, including the Nernst-Haber-Bodenstein Award of the German Bunsen Society in 2009 and a Consolidator Grant „COMOTION“ of the European Research Council in 2013.
Author: Jochen Küpper, DESY, Hamburg (Germany), http://desy.cfel.de/cid/cmi/
Title: Separating Para and Ortho Water
Angewandte Chemie International Edition
Permalink to the original article: http://dx.doi.org/10.1002/anie.201405986
Jochen Küpper | Angewandte Chemie
Barium ruthenate: A high-yield, easy-to-handle perovskite catalyst for the oxidation of sulfides
16.07.2018 | Tokyo Institute of Technology
The secret sulfate code that lets the bad Tau in
16.07.2018 | American Society for Biochemistry and Molecular Biology
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
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16.07.2018 | Physics and Astronomy
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Which Synapse Saw What?
Article Jul 21, 2017 | by Adam Tozer, Ph.D.
Understanding how our brains interpret and process the visual scene has been a matter of intense neuroscientific endeavor since the pioneering work of Hubel and Wiesel in the early 1950’s. They implanted electrodes in the visual cortex of cats, the area of the brain that responds to visual information, and displayed images to the animals. This allowed them to eavesdrop on the neurons by listening for cells that fired in response to the visual stimuli as ‘snaps’, ‘crackles’ and ‘pops’ on their amplifier.
Now, pioneering work from Professor Sonja Hofer’s lab at the Biozentrum, University of Basel, has determined the organization of excitatory synaptic inputs responding to different locations in the visual scene. They achieved this by zooming down to measure the activity of the individual spines which protrude from dendrites, the branches of neurons that receive incoming synaptic information. Their findings mapped the spatial receptive fields in dendritic spines of mouse visual cortex neurons using two-photon calcium imaging.
Visual cortex connectivity and the big picture
Pyramidal neurons in the visual cortex respond to specific attributes of a visual scene or stimuli, such as contour orientations like the leading edge of the light bar in Hubel and Wiesel’s studies described above, or the words on your screen as you read this article. Each neuron responds to this information in a small area of visual space, this area is known as its receptive field.
Learn more: visual cortex also processes auditory information
Pyramidal neurons receive thousands of synaptic inputs onto their tree-like dendrites, but how these synaptic inputs influence the neuron’s activity to contribute to understanding the visual scene remains to be understood. For example, what does the wiring diagram of the cells in the visual cortex look like? Are there rules that govern how these thousands of synapses are arranged on the dendrites of the pyramidal cells?
The Hofer lab set out to investigate the connectional logic between neurons in the visual cortex.
As Sonja states, “If we want to figure out how the brain works, we have to understand how the neurons in the brain are connected with each other.” Adding, “We wanted to find out what information neurons with specific functions receive from the visual scene through their synaptic inputs, and how these inputs are arranged on their dendritic tree. By understanding these factors, we can start to interpret the rules that govern connectivity in cortical circuits.”
Imaging synaptic activity: seeing is believing
Video of trial-averaged responses of neurons in mouse visual cortex to drifting grating stimuli, measured using GCaMP6 and two-photon microscopy. Credit: Sur Lab, MIT.
Zooming in on spines
The group showed the mice a random array of dark or light spots on a screen and recorded how the spines responded to these appearing and disappearing spots. By zooming in on the dendrites and spines of GCamp6-labelled cells, the scientists could map their receptive fields. The group subtracted the fluorescence signal from the dendrite to directly measure the activity in the spines themselves, and show there is a specific mapping of inputs at the level of the synapses that mirrors the area of the visual scene the cell responds to, its receptive field. Spines with correlating receptive fields cluster together along the dendrite, and spines with receptive fields that didn’t overlap were more likely to be further apart on the dendrite.
Sonja explains the relevance of this finding, “Our data show that synaptic inputs onto pyramidal cells in the visual cortex tend to cluster over shorter dendritic distances if they respond to similar visual features that occupy similar regions in visual space.”
She goes on to explain the importance of this finding to the field of visual neuroscience, “Many visual neuroscientists still think that the most important characteristic of a neuron in the visual cortex is which orientation of a bar or an edge it prefers. We show that it is the detailed visual feature the neurons best respond to that determines how these synaptic inputs are organized, and not their orientation preference.”
This clustering arrangement of synaptic inputs on a dendrite makes sense. Inputs that are activated in response to the same feature in a visual scene will more likely induce a response in their neuron if they are active on the same dendrite at the same time.
Read more about synaptic clustering: synaptic clustering in layer 5 neurons of the visual cortex
Long distance connections
The Hofer group also investigated the arrangement of synapses on dendrites in relation to the receptive field of these inputs. They show that inputs from neurons representing similar, nearby visual features in the visual space were more likely to terminate on dendrite branches closer to the cell body.
Interestingly, the researchers revealed that about 30% of the synaptic inputs to the pyramidal neurons still came from distant cells, but these terminated on dendritic branches further away from the cell bodies.
Related: visual cortex involved in eye movement reflex plasticity
These long-range inputs still activated spines, but only if the neurons from which they originated responded to features in the environment that were aligned 'co-axially', a geometric term meaning the feature shares a common axis, to that of the postsynaptic cell.
Together this means that, if you were looking at a long horizontal line like the edge of the wall in the figure below, the image would cross the receptive fields of many cells in your visual cortex that have the same orientation selectivity. Those cells that picked out similar features in the visual scene to those in the receptive field of the purple neuron (dashed purple circle) will also innervate it. This means the blue cell with the overlapping receptive field (dashed blue circle) that also picked out the horizontal edge of the wall would reciprocally excite the purple cell. And the distant green cell (green dashed circle) whose receptive field is also crossed by the wall edge would also excite the purple neuron, albeit synapsing at a more distant location to the blue cell. The orange cell would not signal to the purple neuron because its receptive field does not pick up any similar features. This connectivity enables us to quickly interpret the wall edge as a single long-line across our visual field.
Receptive fields (dashed circles) of neurons in the visual cortex pick out different features of the visual scene.
Visual neuroscientists have known of the long-ranging connections between pyramidal neurons in the visual cortex for a long time, but could only postulate on their importance. By demonstrating that long-ranging neurons pick out similar features in the visual scene and connect to each other represents a significant finding and a big step forward for the field of visual neuroscience.
Further reading: asymmetric circuitry enables movement visualization
Seeing: into the future
New questions now arise, What’s the evolutionary purpose of these long-range projections? Do they enable us to quickly parse the visual scene of our environment? And, could this explain why our brains can be fooled into seeing edges that aren’t there? such as the blue triangle in the foreground of the optical illusion below.
Gestalt phenomena illusion infront of a pyramidal neuron. Do you see a triangle that is not physically there? Credit: Biozentrum, University of Basel.
However, to fully understand how this arrangement of synapses influences the activity of a pyramidal neuron and then all pyramidal neurons in the visual cortex, the authors would need to visualize the activity of all the spines on all the dendrites of one cell. Unfortunately, this is currently impossible owing to technological limitations, as you would need to simultaneously zoom in on all spines on all dendrites within a large 3D area of brain tissue.
Despite this, the findings of this study do provide a revealing insight into the pattern of connectivity in neurons of the visual cortex and open-up a new-level of understanding from which to explore vision.
Biosafety and the Agents of DoomArticle
To combat harmful pathogens it is vitally important that scientists have facilities available that enable them to work on them safely. These facilities should prevent the operator from becoming infected with the agent they are working with and prevent the organism from escaping the laboratory setting and potentially initiating new outbreaks of disease.
Italian Study Shows Being a Child of Same-Sex Parents Does Not Affect Your DevelopmentArticle
Study shows no difference in the development of children from same-sex couples compared to different-sex couples.READ MORE | <urn:uuid:71a4090e-5702-4457-af8d-0721be6cf4c0> | 3.640625 | 1,801 | Truncated | Science & Tech. | 28.454886 | 95,551,024 |
If you missed the blue-sky occultation of Jupiter that happened in broad daylight on November 9, 2004, don’t fret. A more dramatic repeat is at hand, this time in the deepest dark of night. On the morning of December 7th, the thick waning crescent Moon will rise in the east around 2 a.m. local time with bright Jupiter shining close by its sunlit side. As the eerie pair rises higher in the sky, the Moon will draw closer to the planet. Observers in eastern and central North America can then watch as Jupiter disappears behind the Moon’s bright limb, as shown below. The planet reappears out from behind the Moon’s dark, dimly earthlit limb roughly an hour later. Jupiter’s disappearance and reappearance will each take about a minute, while the Moon’s edge advances across the giant planet’s 33-arcsecond-wide face. You’ll need a telescope to watch the disappearance next to the Moon’s dazzlingly daylit landscape, but the reappearance will be easily visible to the naked eye though of course binoculars or a telescope will give a far more impressive view.
Use the two maps (at left and below) to find the circumstances of the disappearance and reappearance at your site. Put a pencil dot on your location, and interpolate between the purple or red lines to find the Universal Time (UT) of the event. (To get Eastern Standard Time, subtract 5 hours from UT; to get Central Standard Time, subtract 6 hours; to get Mountain, subtract 7.) Then interpolate between the green lines to find the altitude of Jupiter and the Moon above your east-southeast horizon at this time. Since the altitude will be rather low at most locations, especially for the disappearance, you may want to scout out an observing site in advance that has a low enough view toward the east-southeast.
A telescope will also show occultations of Jupiter’s Galilean moons: Callisto roughly 14 minutes before Jupiter itself (depending on your location), Ganymede about 4 minutes before, and Europa roughly 2 minutes after. Io is in occultation by Jupiter itself, until it emerges from behind the planet’s eastern limb at 10:12 UT.
Another bonus for telescope users is that the bright side of the Moon the lunar west (celestial east) side will be librated (tipped) into especially good view. Therefore we’ll get a chance to catch sight of elusive Mare Orientale, along with the associated Lacus Autumni and Lacus Veris, on the limb southward from dark Grimaldi as described and pictured in the article "A Rare Glimpse of Mare Orientale."
The occultation will offer a chance for some interesting astrophotography. If you want Jupiter to come out looking larger than a dot, you’ll need to use the afocal technique: shooting through an eyepiece rather than mating a camera body to the telescope itself. Digital point-and-shoots work well for this; buy or make a bracket to hold the camera pointed squarely into the eyepiece (see "Astro Imaging with Digital Cameras"). Experiment beforehand to get everything working right.
Longtime Jupiter observers may be surprised at the planet’s dim surface brightness compared to the sunlit Moon. After all, Jupiter is covered with bright clouds (average albedo 52 percent), while the Moon’s surface is very dark gray dust (average albedo 12 percent). However, this can’t make up for the fact that Jupiter is about six times farther from the Sun and is therefore illuminated by sunlight that’s only 1/36 as bright. | <urn:uuid:21647fc8-76a4-4af4-a870-ad9d9a43416d> | 3.046875 | 770 | Knowledge Article | Science & Tech. | 45.20979 | 95,551,058 |
In the last Astronomy Packet we talked about how scientists study the Earth to understand other worlds. They also study worlds which are similar to each other in order to better understand how these worlds work. Comparing different planets to the Earth and to each other is called Comparative Planetology. In Astronomy Packet # 2 we learned about the Moon and Mercury. We used comparative planetology to understand how they are the same and how they are different. This week we are going to explore the following planets: Venus, Earth and Mars.
In order for life as we know it to exist there must be liquid water. Around every star there is a zone where the temperature is just right for water to remain as a liquid. If the planet is too close to the star, it will be too hot and all its water will evaporate. If the planet is too far from the star, then it will be too cold and so all the water will freeze. But if the planet sits just the right distance from its star, then it will be just the right temperature for the water to remain liquid. This life zone is called the Ecosphere.
The Earth sits almost right in the middle of the Sun’s Ecosphere, or life zone. But guess what? Venus and Mars also sit in the Ecosphere, but Venus is on the very inner edge, and Mars is on the very outer edge. This is the first thing these three planets have in common. All three are within the Sun’s Ecosphere.
Assignment # 1:
What is an Ecosphere?
Check your answer
There are around a star where it is just the right temperature for life to exits. | <urn:uuid:3182efbb-f1fe-4f0f-a603-5c3602671203> | 4.03125 | 343 | Tutorial | Science & Tech. | 61.905987 | 95,551,069 |
Viewings: 11978Astronomers hope that in March 2013 for comet C/2011 L4 can be seen with the naked eye.
Even if the approach of comet C/2011 L4 with the Earth will not be a particularly spectacular event, many of us still hope for this near-sun-comet will be visible even with unprofessional optics, and if very lucky, and to the naked eye.
Comet C/2011 L4 is non-periodic comet. There is a small chance that it could become a Great comet, when it will be near perihelion in March 2013.
Comet C/2011 L4 was opened on 6 June 2011, with the help of telescope Pan-STARRS, located near the summit of Haleakala, Maui (Hawaii).
After the perihelion passage orbital period comets, scientists estimate of approximately 110 000 years. By assumption astronomers, the comet could come from the Oort Cloud, hypothetical spherical region of our Solar System, which is a source of long-period comets. Scientists suggest that the existence of the Oort cloud is not confirmed, but many indirect evidence of its existence.
The Oort cloud is assumed to include two separate areas: the spherical outer Oort cloud and the inner Oort cloud in the shape of a disk. Objects in the Oort cloud largely composed of water, ammonia and methane ice. Astronomers believe that the objects that make up the Oort cloud, formed near the Sun and were scattered far into space by the gravitational effects of the giant planets in the early development of the Solar system.
The picture shows the comet C/2011 L4 dust with his tail. The photo was taken on January 27, 2013 from Australia using 11-inch telescope.
You are reading news В марте 2013 года будем наблюдать за кометой C/2011 L4 if You liked the article В марте 2013 года будем наблюдать за кометой C/2011 L4, prokomentiruet her. | <urn:uuid:b7fcbdbc-87ed-4745-8ad5-2428a618d537> | 3.0625 | 478 | Knowledge Article | Science & Tech. | 62.466923 | 95,551,097 |
Write callbacks to control the interactive behavior of an app. Manage startup tasks and share data within apps.
|Retrieve application-defined data|
|Store application-defined data|
|True if application-defined data exists|
|Remove application-defined data|
|Store or retrieve UI data|
|Create structure containing all child objects of Figure|
|Manage preferences used in uigetpref|
Learn about writing callbacks to control the behavior of apps you create programmatically.
Learn about writing callbacks to control the behavior of apps you create in GUIDE.
Learn how to program specific functionality for different components.
Learn different ways to manage and share data in your app.
Learn how to initialize property values and set defaults before the UI displays.
Learn how to initialize UI components and set defaults in your GUIDE app.
Learn how to control whether callbacks can be interrupted by other callbacks.
Learn how to organize your app code.
Examine a GUIDE app that displays tabular data and two plots.
Create a modal dialog box to confirm an operation.
Examine a GUIDE app displays a list box that users can interact with.
Examine a GUIDE App that analyzes input data and generates frequency and time domain plots.
Examine a GUIDE app that plots workspace variables.
Examine a GUIDE app that uses a timer object to continuously update plot data. | <urn:uuid:d198ec90-b82c-4d04-93a8-6fc3928267b9> | 2.546875 | 299 | Tutorial | Software Dev. | 32.940833 | 95,551,101 |
Can you complete this jigsaw of the multiplication square?
Reasoning about the number of matches needed to build squares that share their sides.
These grids are filled according to some rules - can you complete them?
Charlie and Alison have been drawing patterns on coordinate grids. Can you picture where the patterns lead?
Here is a machine with four coloured lights. Can you develop a strategy to work out the rules controlling each light?
Katie and Will have some balloons. Will's balloon burst at exactly the same size as Katie's at the beginning of a puff. How many puffs had Will done before his balloon burst?
When number pyramids have a sequence on the bottom layer, some interesting patterns emerge...
Can you dissect a square into: 4, 7, 10, 13... other squares? 6, 9, 12, 15... other squares? 8, 11, 14... other squares?
Compare the numbers of particular tiles in one or all of these three designs, inspired by the floor tiles of a church in Cambridge.
A 2 by 3 rectangle contains 8 squares and a 3 by 4 rectangle contains 20 squares. What size rectangle(s) contain(s) exactly 100 squares? Can you find them all?
Alison, Bernard and Charlie have been exploring sequences of odd and even numbers, which raise some intriguing questions...
We can arrange dots in a similar way to the 5 on a dice and they usually sit quite well into a rectangular shape. How many altogether in this 3 by 5? What happens for other sizes?
Can you find a way to identify times tables after they have been shifted up?
Which of these pocket money systems would you rather have?
Cellular is an animation that helps you make geometric sequences composed of square cells.
Investigate and explain the patterns that you see from recording just the units digits of numbers in the times tables.
Susie took cherries out of a bowl by following a certain pattern. How many cherries had there been in the bowl to start with if she was left with 14 single ones?
In this investigation, you are challenged to make mobile phone numbers which are easy to remember. What happens if you make a sequence adding 2 each time?
These alphabet bricks are painted in a special way. A is on one brick, B on two bricks, and so on. How many bricks will be painted by the time they have got to other letters of the alphabet?
Investigate how you can work out what day of the week your birthday will be on next year, and the year after...
A story for students about adding powers of integers - with a festive twist.
In this investigation, we look at Pascal's Triangle in a slightly different way - rotated and with the top line of ones taken off. | <urn:uuid:882a561e-eff2-42a9-87c6-ac791700f6e9> | 3.84375 | 567 | Content Listing | Science & Tech. | 68.781078 | 95,551,105 |
Hamilton-Jacobi Theory and Canonical Transformations
In this chapter we want to present the basic features of the Hamilton—Jacobi theory, the centerpiece of analytical mechanics, which has played a major role in the development of the mathematical foundations of quantum mechanics as well as in the genesis of an analysis on manifolds. This theory is not only based on the fundamental work of Hamilton and Jacobi, but it also incorporates ideas of predecessors such as Fermat, Newton, Huygens and Johann Bernoulli among the old masters and Euler, Lagrange, Legendre, Monge, Pfaff, Poisson and Cauchy of the next generations. In addition the contributions of Lie, Poincaré and E. Cartan had a great influence on its final shaping.
KeywordsVector Field Hamiltonian System Poisson Bracket Symplectic Manifold Canonical Transformation
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Interior Alaska Beekeeper's Calendar
Sunday, June 27, 2010
Queen honeybees are only fertile in the first few days of their lives at which time they mate with up to 21 drones in order to carry enough fertilized eggs for their life time (up to 7 years). Queens then lay up to a couple thousand eggs in a day.
Post a Comment
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Microwave Method of Identifying Explosions
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The informative parameters of microwave signals making it possible for distinguish by means of passive radiolocation a nuclear explosion in the atmosphere among other sources of microwave radiation (lightning or accident at NPP) and to evaluate the power and altitude of the explosion are discussed. The wavelengths falling within the atmospheric transparency range from several millimeters to tens of centimeters are examined.
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- 1.V. F. Fedorov, Yu. B. Kotov, and T. A. Semenova, “Software package for the estimate of the air plasma radiothermal radiation,” in: 13th Int. Conf. on the Methods Aerophysical Research, Novosibirsk, Feb. 5–10, 2007, Pt. III, pp. 95–98.Google Scholar
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- 5.V. F. Fedorov, Yu. B. Kotov, K. S. Mozgov, and T. Semenovs, Microwave Radiation from a Nuclear Explosion, Knizhnyi Dom Librokom, Moscow (2013).Google Scholar
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- 7.Yu. P. Vagin, K. S. Mozgov, T. A. Semenova, and V. F. Fedorov, “Generation of coherent microwave radiation by powerful atmospheric sources,” Elektromagn. Volny i Electron. Sistemy, 16, No. 3, 81–86 (2011).Google Scholar
- 9.GOST 4401-81, Standard Atmosphere. Parameters, Izd. Standartov, Moscow (1981).Google Scholar | <urn:uuid:70936bad-02e0-4007-b02f-fa684901f33c> | 2.65625 | 553 | Truncated | Science & Tech. | 66.982434 | 95,551,138 |
What is carbon dating?
Do you know how Carbon Dating works? The full process, I mean. These are the parts I am interested in: 1. the equipment: who owns them, how many are there; 2. How does the equipment extract the carbon, or otherwise measure carbon?; 3. What is (are) the equations/ scientific theory used to convert the measurements to a date?; 4. How has this process been validated?
I want to say that "carbon dating is a form of chemical romance," but I suppose I should control my urge toward frivolous wordplay.
What I know is that the process involves determining the amounts of isotopes of radioactive carbon present in a sample of carbonaceous material. (Normal carbon in living beings has a small but consistent amount of these isotopes--C13 and C14. Very ancient fossil carbon does not.)
Since the rate at which these isotopes decay is fixed, the relative abundances of stable Carbon-12 and radioactive C-13 and C-14 let you figure out mathematically how long it must have been since the creature lived. Practically, it's mostly C14 that is the object of carbon dating.
As to how it has been validated, it's basically by cross-comparison with other knowledge. For instance, an early validation test was to carbon-date an ancient Egyptian barge whose age was known from the historical record.
Most of your other questions are answered here:
The main one that isn't, I think, is #1. I think the best short answer to that is that there are a great many carbon dating machines, and they are the property of the labs that use them.
by peterxdunn 4 years ago
Does this image prove - beyond all doubt - that God does not exist and that the Bible story...cannot be true?Look very carefully at this picture. It was taken by the Hubble Space Telescope (a true miracle of the modern age). The light from some of the galaxies shown here has been travelling through...
by Stump Parrish 7 years ago
A good friend of mine and i were recently discussing history and the conversation turn to the age of the planet. My friend explained that he had watched a documentory that proved the earth was only 6000 years old and I laughed until I saw he was serious. I asked him how he explained the results of...
by BakerRambles 6 years ago
In response to new technological advances in elemental compositions, could there be a better solution to exact date measurements using forms other than carbon dating?
by Oscar Jones 5 years ago
Do you believe in the biblical flood in the days of Noah? it was recorded as a cataclysmic earth-covering flood, and mentions waters flowing from the deep, (out of the earth, as well as all the water previously being held in a cloud canopy over the earth falling as the first rain on the...
by Paul Wingert 7 years ago
Hardcore creationists drive themselves into a frenzy trying despirately to denounce evolution, carbon dating, and so on. They write books and produce videos on a subject they don't know anything about. 9 times out of 10 their sources are other books and videos created by other creationist with zero...
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|RHODOPHYTA : GIGARTINALES : Kallymeniaceae||RED ALGAE|
Description: A flat, soft, frond growing from a small disc and stipe, usually much branched, basically dichotomously in a fan like manner to a length of 15 cms. The cystocarps are produced in marginal proliferations which can be clearly seen.
Habitat: Common. Epilithic or epiphytic on Laminaria from the upper sublittoral to over 30 m deep. In both sheltered and exposed areas.
Distribution: Widespread and generally distributed in the British Isles from the Shetlands to the Channel Islands. Europe: Mediterranean, Portugal, Spain, Faroes and Norway.
Distribution Map from NBN: Interactive map : National Biodiversity Network mapping facility, data for UK.
WoRMS: Species record : World Register of Marine Species.
|Morton, O. & Picton, B.E. (2016). Callophyllis laciniata (Hudson) Kützing. [In] Encyclopedia of Marine Life of Britain and Ireland. |
http://www.habitas.org.uk/marinelife/species.asp?item=ZM3230 Accessed on 2018-07-18
|Copyright © National Museums of Northern Ireland, 2002-2015| | <urn:uuid:0ef31247-793d-4eb4-b7c2-e4bdb39d1113> | 2.625 | 293 | Knowledge Article | Science & Tech. | 39.707812 | 95,551,166 |
El Niño breaks ANOTHER record: Weather phenomenon pushes temperatures last month to highest ever levels for January
- Temperatures in January were 1.13°C above the 1951-1980 averag
- Previous hottest January was in 2007 when it was 0.95°C above average
- News comes just a month after Nasa declared 2015 hottest year on record
- El Niño's counterpart La Nina is expected to emerge in the coming months
El Niño is continuing to break records after pushing the global average temperature last month to its highest ever level for January.
The overall temperature at our planet's surface was 1.13°C above the 1951-1980 average last month.
The previous hottest month of January, according to Nasa records that go back to 1880, was set in 2007 when it was 0.95°C above average.
Scroll down for video
El Nino is continuing to break records, after pushing the global average temperature last month to its highest ever level for January. Shown here, the pattern of temperature anomalies around the world in January shows particular warmth in the high northern latitudes, across Canada, Greenland and Siberia
WHAT IS EL NIÑO?
El Niño is caused by a shift in the distribution of warm water in the Pacific Ocean around the equator.
Usually the wind blows strongly from east to west, due to the rotation of the Earth, causing water to pile up in the western part of the Pacific.
This pulls up colder water from the deep ocean in the eastern Pacific.
However, in an El Niño, the winds pushing the water get weaker and cause the warmer water to shift back towards the east. This causes the eastern Pacific to get warmer.
But as the ocean temperature is linked to the wind currents, this causes the winds to grow weaker still and so the ocean grows warmer, meaning the El Niño grows.
This change in air and ocean currents around the equator can have a major impact on the weather patterns around the globe by creating pressure anomalies in the atmosphere.
The news comes just a month after Nasa declared 2015 the hottest year on record.
Japan's Meteorological Agency has backed up Nasa's latest claim, after reporting that January's global land and sea-surface temperatures were 0.52 degrees above the average.
Temperatures in January are rising at the rate of about 0.75 degrees per century, the agency added.
El Niño is believed to have hit a peak in January, which contributed to the record-breaking temperatures.
But as Thomas R. Karl, director of NOAA's National Centers for Environmental Information, said last year: 'The trend over time is why we're having a record warm year.'
Discover Magazine points out that global land temperatures have been increasingly steadily since 1880.
Meanwhile, warm temperatures in the Arctic during January have been linked to a different phenomenon known as the Arctic Oscillation.
This involves differences in air pressure over the Arctic and lower latitudes.
'If past events help predict future ones, then we have probably reached the peak of the 2015–2016 El Niño,' Nasa said last month.
'Warmer-than-average waters in the eastern tropical Pacific Ocean should start to cool off and shift westward.'
El Niños are triggered when the steady, westward-blowing trade winds in the Pacific weaken or even reverse direction, triggering a dramatic warming of the upper ocean in the central and eastern tropical Pacific.
Clouds and storms follow the warm water, pumping heat and moisture high into the overlying atmosphere.
global land temperatures have been increasingly steadily since 1880. While El Nino has created a spike in temperatures, it is only one reason why temperatures are heating up. The black line in the graph above shows the annual mean temperature anomaly. The red line showing the 5-year running mean
Warm temperatures in the Arctic during January have been linked to a different phenomenon known as the Arctic Oscillation. This involves differences in air pressure over the Arctic and lower latitudes
These changes alter jet stream paths and affect storm tracks all over the world.
This year's El Niño has caused the warm water layer that is normally piled up around Australia and Indonesia to thin dramatically, while in the eastern tropical Pacific, the normally cool surface waters are blanketed with a thick layer of warm water.
This massive redistribution of heat causes ocean temperatures to rise from the central Pacific to the Americas.
It has sapped Southeast Asia's rain in the process, reducing rainfall over Indonesia and contributing to the growth of massive wildfires that have blanketed the region in choking smoke.
The Japanese Meteorological Agency has also confirmed that January 2016 was the warmest January on record. The graph shows the global average temperatures in January since 1890, when records began
El Niño is also implicated in Indian heat waves caused by delayed monsoon rains, as well as Pacific island sea level drops, widespread coral bleaching that is damaging coral reefs, droughts in South Africa, flooding in South America and a record-breaking hurricane season in the eastern tropical Pacific.
Even as the El Nino weather phenomenon continues to impact global temperatures and crops, its counterpart La Nina is increasingly expected to emerge in the coming months for the first time in four years.
The return of La Nina, Spanish for 'the girl' and characterised by unusually cold ocean temperatures, is possible later this year, the US government forecaster said last week.
WILL EL NINO FAIL TO PROVIDE MUCH NEEDED RAIN TO CALIFORNIA?
Winter has suddenly switched off the rain and flipped on heat up to 95 degrees in California, raising jitters that the strong El Nino might not be the drought-buster the crispy state had hoped.
'Forget El Nino, this is El No-no!' YouTube celebrity Hannah Hart tweeted.
Heat records have fallen across the West in recent days, from Oregon to Phoenix to Los Angeles, where surfers hit the beaches and golfers strolled fairways.
Much of California marked its 10th straight day on Friday without measurable precipitation.
The blue skies were increasingly unwelcome in a state that just logged its four driest years on record. California has been looking for a robust and rainy El Nino to bring it out of mandatory water cutbacks.
National Weather Service forecasters were quick to offer soothing messages of drizzle yet to come.
'No need to be concerned,' forecaster Steve Anderson said.
The balmy weather has 'been awesome. It's been great. But it's not going to last,' he said. 'It's still winter.'
It joined other forecasters in projecting La Nina could follow on the heels of one of the strongest El Ninos on record.
Weather models indicate La Nina conditions, which tend to occur unpredictably every two to seven years, may emerge in the Northern Hemisphere fall.
Meanwhile El Nino - which means 'the little boy' in Spanish - is expected to dissipate during the late spring or early summer, the National Weather Service's Climate Prediction Center (CPC) said.
The phenomenon can be less damaging than El Nino, but severe La Ninas are linked to floods, droughts and hurricanes.
When La Nina last appeared from August 2011 to March 2012, it hurt corn and soybean crops in Argentina and Brazil, brought the worst drought in a century to Texas and increased the number of storms that threatened US coastal regions, like Hurricane Irene.
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From the dirtiest source of energy to the cleanest, abandoned coal mines around the world are getting a second life as sites for large-scale solar farms.
The biggest one yet began operating this weekend—a 150-megawatt floating solar farm in the eastern Chinese city of Huainan. At one time, the mine accounted for nearly 20 percent of the country’s coal reserves; now the world’s biggest floating solar project is sitting atop the lake formed in the collapsed mine.
The project is expected to come into full use in May 2018, at which time it will be able to power around 94,000 homes. Though it eclipses all the other floating solar farms in the world, this one joins another recent project in the same city that, until now, was the largest of its kind in the world. Also atop a former coal mine, the latter project can supply electricity to 15,000 homes and came online in August.
Both projects join the building trend of solar farms replacing abandoned coal mines. In Germany, which ranks third in terms of installed solar capacity countrywide, a coal that is set to close next year is being reimagined as a renewable energy plant able to power 40,000 homes with solar panels and wind turbines.
The U.S. is just behind Germany in amount of installed solar capacity, and is set to turn a strip mine in the Appalachians into a solar power plant that could produce somewhere between 50 to 100MW of power in 2018. And last year the U.K. expressed interest in turning the country’s last deep coal mine into a 5-MW solar farm.
Coal is the generally regarded as the "dirtiest" fossil fuel energy source. It produces the least amount of energy and the greatest amount of pollution per kilogram. And, thankfully, the world is quickly abandoning it: Earlier this Fall, Greenpeace and CoalSwarm found that countries are abandoning coal at an astonishing pace, and hundreds of companies have left the business in recent years. Of the 1,675 companies that have owned coal-fired power plants since 2010, over a quarter 448 companies have left it behind.
At the same time, solar power is taking off. In 2016, solar capacity worldwide leapt by 50 percent with more than 76 gigawatts installed compared to 50GW the year before. The international energy agency predicts that by 2022, more than 920GW will be utilized worldwide.
You wouldn't expect it, but the Kentucky Coal Mining Museum, a museum dedicated to the coal industry, is converting to solar power. Communications director Brandon Robinson said that the project "will help save at least eight to ten thousand dollars, off the energy costs on this building alone." #solarpower #solar #cleanenergy #beyondcoal #renewableenergy #renewables #kentucky #miningcompany #museum #actonclimate #climateaction #climatechange
Using old coal mines to help bump this growth has its advantages. For one, abandoned coal mines often present a land-use challenge. Lakes built inside of them are often high in sulfate, making them unfit for farming purposes. Floating solar farms also work more efficiently than land-bound ones due to the cooling effect of the water, which saves energy that might otherwise be used for cooling the panels. Additionally, having solar panels cover the surface of the lake can help stop evaporation, keeping the lake fuller longer. In all, it's a win-win-win situation for clean, renewable energy.
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