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Generally speaking, conductivity is the rate at which matter or energy can pass through a given material. A material with a high level of electrical conductivity, for instance, would easily accommodate the movement of an electric charge. Of course, this measurement has diverse practical applications, from using conductivity to move heat or energy to using insulation to keep it in place. Each of these uses depends on the kind of activity desired and the kind of conductivity used as a reference.
Thermal conductivity measures the ability of a material to accommodate the movement of thermal energy (heat), measured in Watts per meter Kelvin (W/ mK). Materials with high levels of thermal conductivity are usually used as heat sinks in practical applications, just as materials with low levels of thermal conductivity (high levels of thermal resistivity) are often used as insulation. Although exceptions exist, metals tend to be good thermal conductors and gases tend to be good insulators.
Electrical conductivity, measured in Siemens per meter (S/m), depends on similar molecular structures to thermal conductivity. Metallic and highly polarized materials that conduct heat well likewise are good conductors of electricity. Given the importance of electricity in the modern world--and specifically the importance of moving electricity from generators to users–electrical conductivity is a particularly relevant measurement, used to design electrical transmission systems like copper electrical wires that move energy over long distances with minimal resistance and loss to friction.
Ionic conductivity is a molecular category that measures the ability of a charged particle (an ion) to move through the crystalline structure of a material. Compounds and elements able to accept the movement of an ion through their structure are called electrolytes and are usually solid or liquid. Although ionic conductivity may seem to have fewer practical applications than other and better-known forms of conductivity, measuring and controlling ionic conduction is actually what makes common household objects like microwaves and batteries work.
Hydraulic conductivity describes the rate at which water can move through the porous elements of a surface. Measured empirically or predicted by grain size calculations, hydraulic conductivity is an important consideration for assessing the permeability of soils, rocks and plant layers. Such studies provide critical information for watershed management, agriculture and flood prevention. Hydraulic conductivity also is used to model the behavior of aquifers and subterranean water deposits, shaped by the ability of water to move horizontally and vertically through different materials and geological layers. | <urn:uuid:45f697f9-4ec8-49b1-a5c9-009fcb8429b3> | 4.03125 | 498 | Knowledge Article | Science & Tech. | 4.812347 | 95,556,390 |
Physicists have developed a technique based on optical microscopy that can be used to create images of atoms on the nanoscale. In particular, the new method allows the imaging of quantum dots in a semiconductor chip. Together with colleagues from the University of Bochum, scientists from the University of Basel’s Department of Physics and the Swiss Nanoscience Institute reported the findings in the journal Nature Photonics.
Microscopes allow us to see structures that are otherwise invisible to the human eye. However, conventional optical microscopes cannot be used to image individual molecules and atoms, which measure just fractions of a nanometer across. This has to do with the wave nature of light and the associated laws of physics, which were formulated by the German physicist Ernst Abbe back in 1873.
According to these laws, a microscope’s maximum resolution is equal to half the wavelength of the light used. For example, if you use green light with a wavelength of 500 nanometers, an optical microscope can, at best, distinguish objects at a distance of 250 nanometers.
Switched on and off
In recent years, however, scientists have managed to get around this resolution limit and generate images of structures measuring just a few nanometers across. To do so, they used lasers of various wavelengths to trigger fluorescence in molecules in part of the substance while suppressing it in the surrounding areas.
This allows them to image structures such as dye molecules, which are just a few nanometers in size. The development of this method (Stimulated Emission Depletion, STED) was honored with the Nobel Prize in Chemistry 2014.
For all objects with two energy levels
Timo Kaldewey, from Professor Richard Warburton’s team at the University of Basel’s Department of Physics and Swiss Nanoscience Institute, has now worked with colleagues at Ruhr-University Bochum (Germany) to develop a similar technique that allows the imaging of nanoscale objects, particularly a quantum mechanical two-level system.
The physicists studied what are known as quantum dots, artificial atoms in a semiconductor, which the new method was able to image as bright spots. The scientists excited the atoms with a pulsed laser, which changes its color during each pulse. As a result, the atom’s fluorescence is switched on and off.
Whereas the STED method only works by occupying at least four different energy levels in response to the laser excitation, the new method from Basel also works with atoms that have just two energy states. Two-state systems of this kind constitute important model systems for quantum mechanics.
Unlike STED microscopy, the new method also releases no heat. “This is a huge advantage, as any heat released can destroy the molecules you’re examining,” explains Richard Warburton. “Our nanoscope is suitable for all objects with two energy levels, such as real atoms, cold molecules, quantum dots, or color centers.”
The project received funding from, among other sources, the National Center of Competence in Research “Quantum Science and Technology” (NCCR QSIT), the Swiss National Science Foundation, and the European Union under the FP7 program.
Timo Kaldewey, Andreas V. Kuhlmann, Sascha R. Valentin, Arne Ludwig, Andreas D. Wieck, and Richard J. Warburton
Far-field nanoscopy on a semiconductor quantum dot via a rapid-adiabatic-passage-based switch
Nature Photonics (2017), doi: 10.1038/s41566-017-0079-y
Prof. Dr. Richard Warburton, University of Basel, Department of Physics, tel. +41 61 207 35 60, email: email@example.com
Cornelia Niggli | Universität Basel
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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Another thing you may have noticed when playing around with your triangle is that when the application first starts, the triangle appears to be spinning in place. If you move the triangle to the left, it still rotates, but now it appears to be orbiting the origin rather than spinning in place. This is because the order of the translation and the rotation makes a big difference in the resulting effect.
When a rotation is applied, the rotation always rotates the object around the origin. In your code, you are applying the translation first and then the rotation during every frame. So, when the application first loads, the object is drawn at the origin and the rotation causes it to rotate around the origin, which gives the effect of it spinning in place.
However, once you move the object to the left, adding the rotation to the object so that it rotates around the origin (which now is to the right of the object) causes it to have an orbiting effect.
To get your object to spin in place regardless of where it is, you'll need to apply the rotation first, and then the translation. This will cause the rotation to be applied while the object is at the origin (giving it the effect of spinning in place), and the translation will then move the object and its rotation to the specified location.
For this to work, instead of having a single object representing the world for the triangle, you'll need to add two variables to represent the world of the object (you can also remove the ... | <urn:uuid:7d14ae8d-24b7-4b88-8669-be18ac5f78ae> | 2.65625 | 305 | Tutorial | Software Dev. | 53.250857 | 95,556,400 |
Four new studies involving researchers from the STAR Research Institute shed a new light on the extraordinary planetary system discovered in February 2017.
The second telescope of the European program SPECULOOS, financed by the European Union and managed at ULiège, has just been installed at ESO in Chile.
The researcher is rewarded for his work on the search for planets around neighboring stars. Congratulations !
Michaël Gillon (University of Liège) and Amaury Triaud (University of Cambridge) talk about the discovery of TRAPPIST-1 and the fact that we need to expand our search for life beyond the solar system. An article published in aeon magazine.
Emmanuel Jehin participated in the animations in the Corsica competition, which saw two high school classes win a week in Corsica at the Stareso Oceanographic Station of Liege University.
Michaël Gillon, astronomer at the University of Liège, nominated in the 100 TIME list, the list of the 100 most influential people in the world.
Astronomers of the SPECULOOS Liege team are currently at the European Southern Observatory of Paranal (Chile) to commission the first telescope of the project, which is funded by the European Research Council. This telescope, named Europa, is the first of the four telescopes that will comprise the SPECULOOS Southern Observatory which will soon scout the southern skies in search for TRAPPIST-1-like planetary systems around a large sample of nearby ultracool dwarf stars.
ULg astronomers discovered seven telluric planets around the star TRAPPIST-1. “The TRAPPIST-1 system is the largest treasure of terrestrial planets ever detected around a single star.” This discovery, published this week in the journal Nature, revives the quest for life in the Universe.
Laetitia Delrez used information gathered over a period of four years about discoveries and characterizations of hot Jupiters to complete her thesis. She uncovered a wealth of information about these gas giants that orbit very close to their star. | <urn:uuid:4a454796-85a4-4824-ac68-6a320fd641fa> | 2.859375 | 428 | News (Org.) | Science & Tech. | 30.441574 | 95,556,433 |
The dynamics of a population of the cabbage aphid, Brevicoryne brassicae (L.), was studied to estimate the impact of natural enemies and meteorological factors using simple correlation and stepwise regression. Apterous B. brassicae were sampled by visual search, and natural enemies by suction net and pitfall traps. The aphids began to infest kale in July, reaching peak population in September. The factors Diaeretiella rapae (McIntosh), ground spiders, rainfall and relative humidity showed significant correlation with B. brassicae population, in the period that embraced the whole population survey, which suggests that these factors had an important function in the mortality of the aphid. During the period of highest increase and decline of the population of B. brassicae, ground spiders constituted the most significant mortality factor related with the variation of the population density of the aphid.
Mendeley saves you time finding and organizing research
Choose a citation style from the tabs below | <urn:uuid:323c6b30-60d4-40a6-9bdc-a068fb5e59b8> | 3.15625 | 202 | Academic Writing | Science & Tech. | 21.726085 | 95,556,444 |
+44 1803 865913
By: RW White, JB Reid, AD Black and KW Gillon
93 pages, Dist maps
Between February 1998 and January 1999, the JNCC systematically surveyed seabirds and marine mammals in the waters around the Falkland Islands using vessels of opportunity. For the first time, year round at sea dispersion patterns of these species have been recorded for this important sub-Antarctic region.
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All views have a
mask property that allows you to cut out parts depending on what you need. This mask can be any other kind of
UIView, so you could for example use a label to cut out an image view.
To try it out, first create a view with some obvious content such as a background color:
let redView = UIView(frame: CGRect(x: 50, y: 50, width: 128, height: 128)) redView.backgroundColor = .red view.addSubview(redView)
Now create your mask as a separate
UIView. Although it won’t be directly visible you should give this either a background color or some other content because the alpha channel of this mask determines what shows through in the original view.
To demonstrate this, here’s a mask view that’s the same size as the original view, but it’s offset 64 pixels to the right and has a 64-point corner radius. When used as a mask for the previous view it will have the effect of turning it into a semi-circle:
let maskView = UIView(frame: CGRect(x: 64, y: 0, width: 128, height: 128)) maskView.backgroundColor = .blue maskView.layer.cornerRadius = 64 redView.mask = maskView
The blue background color won’t be visible – that’s just there to make sure all pixels in the mask are opaque.
Available from iOS 8.0
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The Arecibo message is a 1974 interstellar radio message carrying basic information about humanity and Earth sent to globular star cluster M13 in the hope that extraterrestrial intelligence might receive and decipher it. The message was broadcast into space a single time via frequency modulated radio waves at a ceremony to mark the remodeling of the Arecibo radio telescope in Puerto Rico on 16 November 1974. The message was aimed at the current location of M13 some 25,000 light years away because M13 was a large and close collection of stars that was available in the sky at the time and place of the ceremony. The message consisted of 1,679 binary digits, approximately 210 bytes, transmitted at a frequency of 2,380 MHz and modulated by shifting the frequency by 10 Hz, with a power of 450 kW. The "ones" and "zeros" were transmitted by frequency shifting at the rate of 10 bits per second. The total broadcast was less than three minutes.
The number 1,679 was chosen because it is a semiprime (the product of two prime numbers), to be arranged rectangularly as 73 rows by 23 columns. The alternative arrangement, 23 rows by 73 columns, produces jumbled nonsense (as do all other X/Y formats). The message forms the image shown on the right, or its inverse, when translated into graphics, characters, and spaces.
Dr. Frank Drake, then at Cornell University and creator of the Drake equation, wrote the message with help from Carl Sagan, among others. The message consists of seven parts that encode the following (from the top down):
- The numbers one (1) to ten (10) (white)
- The atomic numbers of the elements hydrogen, carbon, nitrogen, oxygen, and phosphorus, which make up deoxyribonucleic acid (DNA) (purple)
- The formulas for the sugars and bases in the nucleotides of DNA (green)
- The number of nucleotides in DNA, and a graphic of the double helix structure of DNA (white & blue)
- A graphic figure of a human, the dimension (physical height) of an average man, and the human population of Earth (red, blue/white, & white respectively)
- A graphic of the Solar System indicating which of the planets the message is coming from (yellow)
- A graphic of the Arecibo radio telescope and the dimension (the physical diameter) of the transmitting antenna dish (purple, white, & blue)
Since it will take nearly 25,000 years for the message to reach its intended destination (and an additional 25,000 years for any reply), the Arecibo message is viewed as a demonstration of human technological achievement, rather than a real attempt to enter into a conversation with extraterrestrials. In fact, the core of M13, to which the message was aimed, will no longer be in that location when the message arrives. However, as the proper motion of M13 is small, the message will still arrive near the center of the cluster. According to the Cornell News press release of November 12, 1999, the real purpose of the message was not to make contact but to demonstrate the capabilities of newly installed equipment.
1 2 3 4 5 6 7 8 9 10 ---------------------- 0 0 0 1 1 1 1 00 00 00 0 1 1 0 0 1 1 00 00 10 1 0 1 0 1 0 1 01 11 01 X X X X X X X X X X <-least-significant-digit marker
Even assuming that recipients would recognize binary, the encoding of the numbers may not be immediately obvious because of the way they have been written. To read the first seven digits, ignore the bottom row, and read them as three binary digits from top to bottom, with the top digit being the most significant. The readings for 8, 9 and 10 are a little different, as they have been given an additional column next to the first (to the right in the image). This is intended to show that numbers too large to fit in a single column can be written in several contiguous ones, where the additional columns do not have the least-significant-digit marker.
H C N O P 1 6 7 8 15 ---------- 0 0 0 1 1 0 1 1 0 1 0 1 1 0 1 1 0 1 0 1 X X X X X
The nucleotides are described as sequences of the five atoms that appear on the preceding line. Each sequence represents the molecular formula of the nucleotide as incorporated into DNA (as opposed to the free form of the nucleotide).
For example, deoxyribose (C5H7O in DNA, C5H10O4 when free), the nucleotide in the top left in the image, is read as:
11000 10000 11010 XXXXX ----- 75010
i.e., 7 atoms of hydrogen, 5 atoms of carbon, 0 atoms of nitrogen, 1 atom of oxygen, and 0 atoms of phosphorus.
11 11 11 11 11 01 11 11 01 11 01 11 10 11 11 01 X
1111111111110111 1111101101011110 (binary) = 4,294,441,822 (decimal)
DNA double helix; the vertical bar represents the number of nucleotides. The value depicted is around 4.3 billion, which was believed to be the case in 1974 when the message was transmitted. It is currently thought that there are about 3.2 billion base pairs in the human genome.
ʌ X011011 | 111111 | 110111 X0111 111011 | 111111 v 110000
1110 (binary) = 14 (decimal)
000011 111111 110111 111011 111111 110110 (binary) = 4,292,853,750 (decimal)
The element in the center represents a human. The element on the left (in the image) indicates the average height of an adult male: 1.764 m (5 ft 9.4 in). This corresponds to the horizontally written binary 14 multiplied by the wavelength of the message (126 mm). The element on the right depicts the size of human population in 1974, around 4.3 billion. In this case, the number is oriented in the data horizontally rather than vertically. The least-significant-digit marker is in the upper left in the image, with bits going to the right and more significant digits below.
Earth Sun Mercury Venus Mars Jupiter Saturn Uranus Neptune Pluto
The solar system, showing the Sun and the planets in the order of their position from the Sun: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune, and Pluto. (Pluto has since been reclassified as a dwarf planet by the International Astronomical Union, but it was still considered a planet at the time the message was transmitted.)
The Earth is the third planet from the Sun; its graphic is shifted up to identify it as the planet from which the signal was sent. Additionally, the human figure is shown just above the Earth graphic.
In addition to showing position, the graphic provides a general, not-to-scale size reference of each planet and the Sun.
bottom two rows: 100101 <--- 111110X --->
100101 111110 (binary) = 2,430 (decimal)
The last part represents the Arecibo radio telescope with its diameter: 2,430 multiplied by the wavelength gives 306.18 m (1,004 ft 6 in). In this case, the number is oriented horizontally, with the least-significant-digit marker to the lower right in the image. The part of the image that looks like a letter "M" is there to demonstrate to the reader of the message that the curved line is a paraboloid mirror.
Message as binary string
00000010101010000000000 00101000001010000000100 10001000100010010110010 10101010101010100100100 00000000000000000000000 00000000000011000000000 00000000001101000000000 00000000001101000000000 00000000010101000000000 00000000011111000000000 00000000000000000000000 11000011100011000011000 10000000000000110010000 11010001100011000011010 11111011111011111011111 00000000000000000000000 00010000000000000000010 00000000000000000000000 00001000000000000000001 11111000000000000011111 00000000000000000000000 11000011000011100011000 10000000100000000010000 11010000110001110011010 11111011111011111011111 00000000000000000000000 00010000001100000000010 00000000001100000000000 00001000001100000000001 11111000001100000011111 00000000001100000000000 00100000000100000000100 00010000001100000001000 00001100001100000010000 00000011000100001100000 00000000001100110000000 00000011000100001100000 00001100001100000010000 00010000001000000001000 00100000001100000000100 01000000001100000000100 01000000000100000001000 00100000001000000010000 00010000000000001100000 00001100000000110000000 00100011101011000000000 00100000001000000000000 00100000111110000000000 00100001011101001011011 00000010011100100111111 10111000011100000110111 00000000010100000111011 00100000010100000111111 00100000010100000110000 00100000110110000000000 00000000000000000000000 00111000001000000000000 00111010100010101010101 00111000000000101010100 00000000000000101000000 00000000111110000000000 00000011111111100000000 00001110000000111000000 00011000000000001100000 00110100000000010110000 01100110000000110011000 01000101000001010001000 01000100100010010001000 00000100010100010000000 00000100001000010000000 00000100000000010000000 00000001001010000000000 01111001111101001111000
- Active SETI—METI (Messaging to Extra-Terrestrial Intelligence)
- A Message from Earth
- Communication with Extraterrestrial Intelligence (CETI)
- Cosmic Call
- Pioneer plaque
- Voyager Golden Record
- Wow! signal (mentions reply in 2012 using Arecibo)
- "Cornell News: It's the 25th anniversary of Earth's first (and only) attempt to phone E.T." Nov 12, 1999. Archived from the original on 2008-08-02. Retrieved 2008-03-29.
- Johnson, Steven (28 June 2017). "Greetings, E.T. (Please Don't Murder Us.)". The New York Times. Retrieved 28 June 2017.
- Larry Klaes (2005-11-30). "Making Contact". Ithaca Times. Archived from the original on 2009-01-07. Retrieved 2007-07-27.
- Jay M. Pasachoff. "Chapter 20: Life in the Universe". Williams.edu. Retrieved 2007-05-05.
- Cassiday, George. "The Arecibo Message". Retrieved 12 Oct 2013.
- Dave Deamer (December 4, 2009). "In regard to the email from". Science 2.0.
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Ionization or ionisation, is the process by which an atom or a molecule acquires a negative or positive charge by gaining or losing electrons to form ions, often in conjunction with other chemical changes. Ionization can result from the loss of an electron after collisions with subatomic particles, collisions with other atoms, molecules and ions, or through the interaction with electromagnetic radiation. Heterolytic bond cleavage and heterolytic substitution reactions can result in the formation of ion pairs. Ionization can occur through radioactive decay by the internal conversion process, in which an excited nucleus transfers its energy to one of the inner-shell electrons causing it to be ejected.
Everyday examples of gas ionization are such as within a fluorescent lamp or other electrical discharge lamps. It is also used in radiation detectors such as the Geiger-Müller counter or the ionization chamber. The ionization process is widely used in a variety of equipment in fundamental science (e.g., mass spectrometry) and in industry (e.g., radiation therapy).
Negatively charged ions are produced when a free electron collides with an atom and is subsequently trapped inside the electric potential barrier, releasing any excess energy. The process is known as electron capture ionization.
Positively charged ions are produced by transferring a sufficient amount of energy to a bound electron in a collision with charged particles (e.g. ions, electrons or positrons) or with photons. The threshold amount of the required energy is known as ionization potential. The study of such collisions is of fundamental importance with regard to the few-body problem (see article on few-body systems), which is one of the major unsolved problems in physics. Kinematically complete experiments, i.e. experiments in which the complete momentum vector of all collision fragments (the scattered projectile, the recoiling target-ion, and the ejected electron) are determined, have contributed to major advances in the theoretical understanding of the few-body problem in recent years.
The Townsend discharge is a good example of the creation of positive ions and free electrons due to ion impact. It is a cascade reaction involving electrons in a region with a sufficiently high electric field in a gaseous medium that can be ionized, such as air. Following an original ionization event, due to such as ionizing radiation, the positive ion drifts towards the cathode, while the free electron drifts towards the anode of the device. If the electric field is strong enough, the free electron gains sufficient energy to liberate a further electron when it next collides with another molecule. The two free electrons then travel towards the anode and gain sufficient energy from the electric field to cause impact ionization when the next collisions occur; and so on. This is effectively a chain reaction of electron generation, and is dependent on the free electrons gaining sufficient energy between collisions to sustain the avalanche.
The trend in the ionization energy of atoms is often used to demonstrate the periodic behavior of atoms with respect to the atomic number, as summarized by ordering atoms in Mendeleev's table. This is a valuable tool for establishing and understanding the ordering of electrons in atomic orbitals without going into the details of wave functions or the ionization process. An example is presented in figure 1. The periodic abrupt decrease in ionization potential after rare gas atoms, for instance, indicates the emergence of a new shell in alkali metals. In addition, the local maximums in the ionization energy plot, moving from left to right in a row, are indicative of s, p, d, and f sub-shells.
Classical physics and the Bohr model of the atom can qualitatively explain photoionization and collision-mediated ionization. In these cases, during the ionization process, the energy of the electron exceeds the energy difference of the potential barrier it is trying to pass. The semi-classical description, however, cannot describe tunnel ionization since the process involves the passage of electron through a classically forbidden potential barrier.
The interaction of atoms and molecules with sufficiently strong laser pulses leads to the ionization to singly or multiply charged ions. The ionization rate, i.e. the ionization probability in unit time, can only be calculated using quantum mechanics. In general, the analytic solutions are not available, and the approximations required for manageable numerical calculations do not provide accurate enough results. However, when the laser intensity is sufficiently high, the detailed structure of the atom or molecule can be ignored and analytic solution for the ionization rate is possible.
Tunnel ionization is ionization due to quantum tunneling. In classical ionization, an electron must have enough energy to make it over the potential barrier, but quantum tunneling allows the electron simply to go through the potential barrier instead of going all the way over it because of the wave nature of the electron. The probability of an electron's tunneling through the barrier drops off exponentially with the width of the potential barrier. Therefore, an electron with a higher energy can make it further up the potential barrier, leaving a much thinner barrier to tunnel through and, thus, a greater chance to do so. In practice, tunnel ionization is observable when the atom or molecule is interacting with near-infrared strong laser pulses. This process can be understood as a process by which a bounded electron, through the absorption of more than one photon from the laser field, is ionized. This picture is generally known as multiphoton ionization (MPI).
Keldysh modeled the MPI process as a transition of the electron from the ground state of the atom to the Volkov states. In this model the perturbation of the ground state by the laser field is neglected and the details of atomic structure in determining the ionization probability are not taken into account. The major difficulty with Keldysh's model was its neglect of the effects of Coulomb interaction on the final state of the electron. As it is observed from figure, the Coulomb field is not very small in magnitude compared to the potential of the laser at larger distances from the nucleus. This is in contrast to the approximation made by neglecting the potential of the laser at regions near the nucleus. Perelomov et al. included the Coulomb interaction at larger internuclear distances. Their model (which we call PPT model) was derived for short range potential and includes the effect of the long range Coulomb interaction through the first order correction in the quasi-classical action. Larochelle et al. have compared the theoretically predicted ion versus intensity curves of rare gas atoms interacting with a Ti:Sapphire laser with experimental measurement. They have shown that the total ionization rate predicted by the PPT model fit very well the experimental ion yields for all rare gases in the intermediate regime of Keldysh parameter.
The rate of MPI on atom with an ionization potential in a linearly polarized laser with frequency is given by
The coefficients , and are given by
The coefficient is given by
The quasi-static tunnelling (QST) is the ionization whose rate can be satisfactorily predicted by the ADK model, i.e. the limit of the PPT model when approaches zero. The rate of QST is given by
As compared to the absence of summation over n, which represent different above threshold ionization (ATI) peaks, is remarkable.
The calculations of PPT are done in the E-gauge, meaning that the laser field is taken as electromagnetic waves. The ionization rate can also be calculated in A-gauge, which emphasis the particle nature of light (absorbing multiple photons during ionization). This approach was adopted by Krainov model based on the earlier works of Faisal and Reiss. The resulting rate is given by
where, is the minimum number of photons necessary to ionize the atom, , ( is the ponderomotive energy), is the double Bessel function, , where is the angle between the momentum of the electron, p, and the electric field of the laser, F, and, the symbol FT denotes the three-dimensional Fourier transformation. Finally, incorporates the Coulomb correction in the SFA model.
In calculating the rate of MPI of atoms only transitions to the continuum states are considered. Such an approximation is acceptable as long as there is no multiphoton resonance between the ground state and some excited states. However, in real situation of interaction with pulsed lasers, during the evolution of laser intensity, due to different Stark shift of the ground and excited states there is a possibility that some excited state go into multiphoton resonance with the ground state. Within the dressed atom picture, the ground state dressed by photons and the resonant state undergo an avoided crossing at the resonance intensity . The minimum distance, , at the avoided crossing is proportional to the generalized Rabi frequency, coupling the two states. According to Story et al., the probability of remaining in the ground state, , is given by
where is the time-dependent energy difference between the two dressed states. In interaction with a short pulse, if the dynamic resonance is reached in the rising or the falling part of the pulse, the population practically remains in the ground state and the effect of multiphoton resonances may be neglected. However, if the states go onto resonance at the peak of the pulse, where , then the excited state is populated. After being populated, since the ionization potential of the excited state is small, it is expected that the electron will be instantly ionized.
In 1992, de Boer and Muller showed that Xe atoms subjected to short laser pulses could survive in the highly excited states 4f, 5f, and 6f . These states were believed to have been excited by the dynamic Stark shift of the levels into multiphoton resonance with the field during the rising part of the laser pulse. Subsequent evolution of the laser pulse did not ionize completely these states leaving behind some highly excited atoms. We shall refer to this phenomenon as "population trapping".
We mention the theoretical calculation that incomplete ionization occurs whenever there is parallel resonant excitation into a common level with ionization loss. We consider a state such as 6f of Xe which consists of 7 quasi-degnerate levels in the range of the laser bandwidth. These levels along with the continuum constitute a lambda system. The mechanism of the lambda type trapping is schematically presented in figure. At the rising part of the pulse (a) the excited state (with two degenerate levels 1 and 2) are not in multiphoton resonance with the ground state. The electron is ionized through multiphoton coupling with the continuum. As the intensity of the pulse is increased the excited state and the continuum are shifted in energy due to the Stark shift. At the peak of the pulse (b) the excited states go into multiphoton resonance with the ground state. As the intensity starts to decrease (c), the two state are coupled through continuum and the population is trapped in a coherent superposition of the two states. Under subsequent action of the same pulse, due to interference in the transition amplitudes of the lambda system, the field cannot ionize the population completely and a fraction of the population will be trapped in a coherent superposition of the quasi degenerate levels. According to this explanation the states with higher angular momentum- with more sublevels- would have a higher probability of trapping the population. In general the strength of the trapping will be determined by the strength of the two photon coupling between the quasi-degenerate levels via the continuum.In 1996, using the very stable laser and by minimizing the masking effects of the focal region expansion with increasing intensity, Talebpour et al. observed structures on the curves of singly charged ions of Xe, Kr and Ar. These structures were attributed to electron trapping in the strong laser field. A more unambiguous demonstration of population trapping has been reported by T. Morishita and C. D. Lin.
The phenomenon of non-sequential ionization (NSI) of atoms exposed to intense laser fields has been a subject of many theoretical and experimental studies since 1983. The pioneering work began with the observation of a “knee” structure on the Xe2+ ion signal versus intensity curve by L’Huillier et al. From the experimental point of view, the NS double ionization refers to processes which somehow enhance the rate of production of doubly charged ions by a huge factor at intensities below the saturation intensity of the singly charged ion. Many, on the other hand, prefer to define the NSI as a process by which two electrons are ionized nearly simultaneously. This definition implies that apart from the sequential channel there is another channel which is the main contribution to the production of doubly charged ions at lower intensities. The first observation of triple NSI in argon interacting with a 1 µm laser was reported by Augst et al. Later, systematically studying the NSI of all rare gas atoms, the quadruple NSI of Xe was observed. The most important conclusion of this study was the observation of the following relation between the rate of NSI to any charge state and the rate of tunnel ionization (predicted by the ADK formula) to the previous charge states;
where is the rate of quasi-static tunneling to i'th charge state and are some constants depending on the wavelength of the laser (but not on the pulse duration).
Two models have been proposed to explain the non-sequential ionization; the shake-off model and electron re-scattering model. The shake-off (SO) model, first proposed by Fittinghoff et al., is adopted from the field of ionization of atoms by X rays and electron projectiles where the SO process is one of the major mechanisms responsible for the multiple ionization of atoms. The SO model describes the NS process as a mechanism where one electron is ionized by the laser field and the departure of this electron is so rapid that the remaining electrons do not have enough time to adjust themselves to the new energy states. Therefore, there is a certain probability that, after the ionization of the first electron, a second electron is excited to states with higher energy (shake-up) or even ionized (shake-off). We should mention that, until now, there has been no quantitative calculation based on the SO model, and the model is still qualitative.
The electron rescattering model was independently developed by Kuchiev, Schafer et al, Corkum, Becker and Faisal and Faisal and Becker. The principal features of the model can be understood easily from Corkum's version. Corkum's model describes the NS ionization as a process whereby an electron is tunnel ionized. The electron then interacts with the laser field where it is accelerated away from the nuclear core. If the electron has been ionized at an appropriate phase of the field, it will pass by the position of the remaining ion half a cycle later, where it can free an additional electron by electron impact. Only half of the time the electron is released with the appropriate phase and the other half it never return to the nuclear core. The maximum kinetic energy that the returning electron can have is 3.17 times the ponderomotive potential () of the laser. Corkum's model places a cut-off limit on the minimum intensity ( is proportional to intensity) where ionization due to re-scattering can occur.
The re-scattering model in Kuchiev's version (Kuchiev's model) is quantum mechanical. The basic idea of the model is illustrated by Feynman diagrams in figure a. First both electrons are in the ground state of an atom. The lines marked a and b describe the corresponding atomic states. Then the electron a is ionized. The beginning of the ionization process is shown by the intersection with a sloped dashed line. where the MPI occurs. The propagation of the ionized electron in the laser field, during which it absorbs other photons (ATI), is shown by the full thick line. The collision of this electron with the parent atomic ion is shown by a vertical dotted line representing the Coulomb interaction between the electrons. The state marked with c describes the ion excitation to a discrete or continuum state. Figure b describes the exchange process. Kuchiev's model, contrary to Corkum's model, does not predict any threshold intensity for the occurrence of NS ionization.
Kuciev did not include the Coulomb effects on the dynamics of the ionized electron. This resulted in the underestimation of the double ionization rate by a huge factor. Obviously, in the approach of Becker and Faisal (which is equivalent to Kuchiev's model in spirit), this drawback does not exist. In fact, their model is more exact and does not suffer from the large number of approximations made by Kuchiev. Their calculation results perfectly fit with the experimental results of Walker et al. Becker and Faisal have been able to fit the experimental results on the multiple NSI of rare gas atoms using their model. As a result the electron re-scattering can be taken as the main mechanism for the occurrence of the NSI process.
The ionization of inner valance electrons are responsible for the fragmentation of polyatomic molecules in strong laser fields. According to a qualitative model the dissociation of the molecules occurs through a three-step mechanism:
The short pulse induced molecular fragmentation may be used as an ion source for high performance mass spectroscopy. The selectivity provided by a short pulse based source is superior to that expected when using the conventional electron ionization based sources, in particular when the identification of optical isomers is required.
Studying the strong field ionization of the atom in so called Kramers-Henneberger (K-H) frame leads to the conclusion that the ionization efficiency strongly depends on the temporal details of the ionizing pulse but not necessarily on the field strength and the total energy of the ionizing pulse pumped into the atom. The Kramers-Henneberger frame is the non-intertial frame moving with the free electron under the influence of the harmonic laser pulse. The free electron solution of the Newton equations for the electron in one dimension in the harmonic laser field
will be also harmonic
The frame comoving with this electron will be obtained by the coordinate transformation
while the added Coulomb potential will be
The full cycle time-average of that potential which is
will be the even function of and therefore having the maximum at while for that initial condition the solution will be in the K-H and it will be therefore identical to the free electron solution in the laboratory frame. The electron velocity on the other hand is phase shifted both to the field strength and to the electron position:
Therefore considering the wavelet pulses and defining the ionization as the full escape from the line segment of the length 2r (or from the spherical region in three dimensions) the full ionization happens in the classical model after the time or no ionization at all depending if the harmonic field wavelet is cut at the zero minimum or the maximum velocity.
A substance may dissociate without necessarily producing ions. As an example, the molecules of table sugar dissociate in water (sugar is dissolved) but exist as intact neutral entities. Another subtle event is the dissociation of sodium chloride (table salt) into sodium and chlorine ions. Although it may seem as a case of ionization, in reality the ions already exist within the crystal lattice. When salt is dissociated, its constituent ions are simply surrounded by water molecules and their effects are visible (e.g. the solution becomes electrolytic). However, no transfer or displacement of electrons occurs. Actually, the chemical synthesis of salt involves ionization. This is a chemical reaction. | <urn:uuid:23f58f65-0878-4489-b87b-51e9f2357109> | 3.703125 | 4,062 | Knowledge Article | Science & Tech. | 31.315895 | 95,556,529 |
A beam trawl was used to sample fish associated with the seagrass Posidonia australis between September 1988 and June 1990. We describe variation in abundance of fish at two spatial scales: among three seagrass beds 1-10 km apart within each of three estuaries, and among the estuaries separated by at least 100 km. Most species had significant differences in abundance among sites and estuaries that changed through time. However, many species also had consistent patterns in abundance among sites and among estuaries. For example, there were large and consistent differences in the abundance of many species among the three estuaries. Widespread changes in abundance (Le. changes that took place at all sites within an estuary or in most estuaries) were not common. The two spatial scales used in this study are also logical scales for management of seagrass habitats. The consistent differences in abundance of some fish found at both spatial scales will complicate management decisions.
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posted by Student
Two gases are mixed in a 10.0L fixed volume flask: 8.0 L of O2 at 2.00 atm and 2.0 L of N2 at 3.00 atm.
A) Calculate the partial pressure for each gas and the total pressure.
I got ...
PO2 = 1.60 atm
PN2= 0.600 atm
B) How much (volume in liters) argon at 5.0 atm must be added to the 10.0 L flask to lower the mole fraction of oxygen to 1/2 ( i.e., to get XO2=0.5)?
Hint: maybe it is easier to do part C first?
C) What is the total pressure from part B (Ar, O2, N2)?
See your post above. | <urn:uuid:87687d1f-6586-470b-9f9b-2ceac2d524b4> | 3.265625 | 179 | Q&A Forum | Science & Tech. | 115.097768 | 95,556,542 |
posted by cylinder
The table below shows how the braking distance x for a car depends on its initial speed u
u / ms-1 5.0 10 20 4
x / m 2.0 8.0 32 128
the reaction time of a driver is 0.60s. Calculate the sopping distance of the car when u= 30ms-1.
The mark scheme says:
Thinking distance= 30 X 0.6 =18m which I understand fully.
BRAKING DISTANCE =0.08 * U^2= 0.08 * 30^2= 72m IS THE BIT I DON’T UNDERSTAND. CAN SOMEONE PLEASE EXPALIN THE BRAKING DISTANCE STAGE AND WHY AND HOW YOU DO THIS BIT AS WELL AS ALL EQUATIONS INVOLVED!
Stopping distance= 18 +72= 90m which I understand fully.
Explain the working out of the braking distance for this question.
As physics - cylinder Thursday, November 9, 2017 at 7:37am
I wrote what I do know and the caps lock is what I dont know, and that is the working out for braking distance shown above is confusing to me.
As physics - Damon Thursday, November 9, 2017 at 8:39am
your table makes no sense to me
v = Vi + a t where t is AFTER 0.6 s
v = 30 + a t
x = Xi + Vi t + (1/2) a t^2
a will be negative of course
Xi is 18 when t = 0
x = 18 + 30 t + (1/2) a t^2
remember total stopping time = t + .6
As physics - cylinder Thursday, November 9, 2017 at 9:27am
I am in as and we dont use those symbols so im confused
Sorry for the repost i didnt understand and i just wanted to show how the working and answer went so someone can better help me
I had this question too and didnt understand it either when i went through thisquestionin a level we dont usae Xi or any of those please write in ful lsentencs ad clearly explai
What i think
someone used the equation v=u+at and s=ut+1/2at^2
if t is zero then i think v is 30 after putting the numbers in. then.. oim confused using suvat and where the numbers came from please help
Please help i hvae been confused on this for ages
You have not posted all the information needed.
9.81 is the acceleration of gravity which has nothing to do with this. Why is there a 4 above 128?
Please post the complete problem you were given as given.
if acceleration and force is constant
(1/2) v^2 = F d
or initial kinetic energy = work done by F
Q11.The table below shows how the braking distance x for a car depends on its initial speed u.
| u / ms-1 | 5 | 10 | 20 | 40 |
| X / M | 2 | 8 | 32 | 128 |
The relationship between x and u is: doubling speed increases distance by a factor of 4.
i)The reaction time of a driver is 0.60s. Calculate the stopping distance of the car when u is 30ms-1.
Thinking distance= 18m
and i didntknow how to work out braking distance so i looked at the mark scheme to get this number
so braking distance=72m
then i used this number to get the stoppign distance and got:
18m + 72m = 90m stopping distance.
Please show mehow to work out braking distance for this questions, show where you got numbersfrom, what equations used and full wqriting not jut symbols please/
by the wa for the table
5 is above 2
10 is above 8
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Volcanic Explosivity Index
The Volcanic Explosivity Index (VEI) is a relative measure of the explosiveness of volcanic eruptions. It was devised by Chris Newhall of the United States Geological Survey and Stephen Self at the University of Hawaii in 1982.
Volume of products, eruption cloud height, and qualitative observations (using terms ranging from "gentle" to "mega-colossal") are used to determine the explosivity value. The scale is open-ended with the largest volcanoes in history given magnitude 8. A value of 0 is given for non-explosive eruptions, defined as less than 10,000 m3 (350,000 cu ft) of tephra ejected; and 8 representing a mega-colossal explosive eruption that can eject ×1012 m3 (240 cubic miles) of tephra and have a cloud column height of over 20 km (12 mi). The scale is logarithmic, with each interval on the scale representing a tenfold increase in observed ejecta criteria, with the exception of between VEI 0, VEI 1 and VEI 2. 1.0
With indices running from 0 to 8, the VEI associated with an eruption is dependent on how much volcanic material is thrown out, to what height, and how long the eruption lasts. The scale is logarithmic from VEI 2 and up; an increase of 1 index indicates an eruption that is 10 times as powerful. As such there is a discontinuity in the definition of the VEI between indices 1 and 2. The lower border of the volume of ejecta jumps by a factor of 100 from 10,000 to 1,000,000 m3 (350,000 to 35,310,000 cu ft) while the factor is 10 between all higher indices. In the following table, the frequency of each VEI indicates the approximate frequency of new eruptions of that VEI or higher.
|VEI||Ejecta volume (bulk)||Classification||Description||Plume||Frequency||Tropospheric
|0||< 104 m3||Hawaiian||Effusive||< 100 m||continuous||negligible||none|
|Kīlauea, Piton de la Fournaise, Erebus|
|1||> 104 m3||Hawaiian / Strombolian||Gentle||100 m – 1 km||daily||minor||none|
|Stromboli (since Roman times), Nyiragongo (2002), Raoul Island (2006)|
|2||> 106 m3||Strombolian / Vulcanian||Explosive||1–5 km||every two weeks||moderate||none|
|Unzen (1792), Cumbre Vieja (1949), Galeras (1993), Sinabung (2010)|
|3||> 107 m3||Vulcanian / Peléan/Sub-Plinian||Catastrophic||3–15 km||3 months||substantial||possible|
|Lassen Peak (1915), Nevado del Ruiz (1985), Soufrière Hills (1995), Nabro (2011), Ontake (2014)|
|4||> 0.1 km3||Peléan / Plinian/Sub-Plinian||Cataclysmic||> 10 km (Plinian or sub-Plinian)||18 months||substantial||definite|
|Laki (1783), Mayon (1814), Pelée (1902), Sakurajima (1914), Galunggung (1982), Eyjafjallajökull (2010), Calbuco (2015)|
|5||> 1 km3||Peléan/Plinian||Paroxysmic||> 10 km (Plinian)||12 years||substantial||significant|
|Vesuvius (79), Fuji (1707), Tarawera (1886), Agung (1963), St. Helens (1980), Hudson (1991), Puyehue (2011)|
|6||> 10 km3||Plinian / Ultra-Plinian||Colossal||> 20 km||50–100 yrs||substantial||substantial|
|Laach Lake Volcano (c. 12,900 BC), Veniaminof (c. 1750 BC), Lake Ilopango (535), Huaynaputina (1600), Krakatoa (1883), Santa Maria (1902), Novarupta (1912), Pinatubo (1991)|
|7||> 100 km3||Ultra-Plinian||Super-colossal||> 20 km||500–1,000 yrs||substantial||substantial|
|Aira Caldera (22,000 BC), Kikai Caldera (4,300 BC), Cerro Blanco (c. 2300 BC), Thera (c. 1620 BC), Taupo (180), Baekdu (946), Samalas (1257), Tambora (1815)|
|8||> 1000 km3||Ultra-Plinian||Mega-colossal||> 20 km||> 50,000 yrs||vast||vast|
|La Garita (26,300,000 BC), Cerro Galán (2,200,000 BC), Huckleberry Ridge Tuff (2,100,000 BC), Yellowstone (630,000 BC), Whakamaru (in TVZ) (254,000 BC), Toba (74,000 BC), Taupo (25,360 BC)|
About 40 eruptions of VEI 8 magnitude within the last 132 million years (Mya) have been identified, of which 30 occurred in the past 36 Mya. Considering the estimated frequency is > 50,000 years, there are likely many such eruptions in the last 132 Mya that are not yet known. Based on incomplete statistics, other authors assume that at least 60 VEI 8 eruptions have been identified. The most recent is Lake Taupo's Oruanui eruption, 25,360 years ago, which means that there have not been any Holocene eruptions with a VEI of 8.
There have been at least 10 eruptions of VEI 7 in the last 10,000 years. There are also 58 plinian eruptions, and 13 caldera-forming eruptions, of large, but unknown magnitudes. By 2010, the Global Volcanism Program of the Smithsonian Institution had catalogued the assignment of a VEI for 7,742 volcanic eruptions that occurred during the Holocene (the last 11,700 years) which account for about 75% of the total known eruptions during the Holocene. Of these 7,742 eruptions, about 49% have a VEI of ≤ 2, and 90% have a VEI ≤ 3.
Under the VEI, ash, lava, lava bombs, and ignimbrite are all treated alike. Density and vesicularity (gas bubbling) of the volcanic products in question is not taken into account. In contrast, the DRE (dense-rock equivalent) is sometimes calculated to give the actual amount of magma erupted. Another weakness of the VEI is that it does not take into account the power output of an eruption, which makes the VEI extremely difficult to determine with prehistoric or unobserved eruptions.
Although VEI is quite suitable for classifying the explosive magnitude of eruptions, the index is not as significant as sulphur dioxide emissions in quantifying their atmospheric and climatic impact, as a 2004 paper by Georgina Miles, Roy Grainger and Eleanor Highwood points out.
"Tephra, or fallout sediment analysis, can provide an estimate of the explosiveness of a known eruption event. It is, however, not obviously related to the amount of SO2 emitted by the eruption. The Volcanic Explosivity Index (VEI) was derived to catalogue the explosive magnitude of historical eruptions, based on the order of magnitude of erupted mass, and gives a general indication as to the height the eruptive column reached. The VEI itself is inadequate for describing the atmospheric effects of volcanic eruptions. This is clearly demonstrated by two eruptions, Agung (1963) and El Chichón (1982). Their VEI classification separates them by an order of magnitude in explosivity, although the volume of SO2 released into the stratosphere by each was measured to be broadly similar, as shown by the optical depth data for the two eruptions."
Lists of large eruptions
- Timeline of volcanism on Earth (mostly VEI 6, within 2 kya)
- List of large volcanic eruptions of the 19th century (≥ VEI 4)
- List of large volcanic eruptions of the 20th century (≥ VEI 4)
- List of large volcanic eruptions in the 21st century (≥ VEI 4)
- List of large volcanic eruptions (mostly VEI 6–8, within 50 Mya)
- List of largest volcanic eruptions (VEI 7–8, mostly within 500 Mya)
- Newhall, Christopher G.; Self, Stephen (1982). "The Volcanic Explosivity Index (VEI): An Estimate of Explosive Magnitude for Historical Volcanism" (PDF). Journal of Geophysical Research. 87 (C2): 1231–1238. Bibcode:1982JGR....87.1231N. doi:10.1029/JC087iC02p01231. Archived from the original (PDF) on December 13, 2013.
- "Volcanic Explosivity Index (VEI)". Global Volcanism Program. Smithsonian National Museum of Natural History. Archived from the original on November 10, 2011. Retrieved August 21, 2014.
- Dosseto, A. (2011). Turner, S. P.; Van-Orman, J. A., eds. "Timescales of Magmatic Processes: From Core to Atmosphere". Wiley-Blackwell. ISBN 978-1-4443-3260-5.
- Rothery, David A. (2010). "Volcanoes, Earthquakes and Tsunamis". Teach Yourself.
- Froggatt, P. C.; Nelson, C. S.; Carter, L.; Griggs, G.; Black, K. P. (13 February 1986). "An exceptionally large late Quaternary eruption from New Zealand". Nature. 319 (6054): 578–582. Bibcode:1986Natur.319..578F. doi:10.1038/319578a0. Retrieved 23 August 2010.
- BG, Mason (2004). "The size and frequency of the largest explosive eruptions on Earth". Bull Volcanol. 66 (8): 735. Bibcode:2004BVol...66..735M. doi:10.1007/s00445-004-0355-9.
- Bryan, S.E. (2010). "The largest volcanic eruptions on Earth". Earth-Science Reviews. 102 (3–4): 207. Bibcode:2010ESRv..102..207B. doi:10.1016/j.earscirev.2010.07.001.
- Mason, Ben G.; Pyle, David M.; Oppenheimer, Clive (2004). "The size and frequency of the largest explosive eruptions on Earth". Bulletin of Volcanology. 66 (8): 735–748. Bibcode:2004BVol...66..735M. doi:10.1007/s00445-004-0355-9.
- Siebert, L.; Simkin, T.; Kimberly, P. (2010). Volcanoes of the World (3rd ed.). University of California Press. pp. 28–38. ISBN 978-0-520-26877-7.
- Miles, M. G.; Grainger, R. G.; Highwood, E. J. (2004). "Volcanic Aerosols: The significance of volcanic eruption strength and frequency for climate" (PDF). Quarterly Journal of the Royal Meteorological Society. 130 (602): 2361–2376. doi:10.1256/qj.30.60 (inactive 2018-06-04).
- VEI glossary entry from a USGS website
- How to measure the size of a volcanic eruption, from The Guardian
- The size and frequency of the largest explosive eruptions on Earth, a 2004 article from the Bulletin of Volcanology
- List of Large Holocene Eruptions (VEI > 4) from the Smithsonian Global Volcanism Program | <urn:uuid:930cde3a-3c2e-4d05-986f-76311bc959b3> | 3.71875 | 2,708 | Knowledge Article | Science & Tech. | 71.320264 | 95,556,562 |
There’s no doubt that tidal power is severely lagging behind other forms of renewable energy like wind and solar power. However, as two-thirds of the Earth’s surface is covered by water, we’d be crazy not to try and harness energy from water that’s continuously in motion.
Given the high costs of creating new technology and the fact that there is yet to be an agreed upon design that works, the tidal energy industry is yet to take off. Germany based company, REAC Energy GmbH wants to change that.
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They have developed the StreamCube, a scalable, cube-shaped water wheel that might be what the market has been waiting for to make tidal power commercially viable. The device is similar to the conventional water wheel, only it’s anchored deep underwater and uses currents to produce energy.
The module works using vertical rotor axes that are set in motion by the pressure of inflowing water. Depending on the positioning of the rotor, the blades fold on or off. The StreamCube units can also be lined up or stacked depending on what they are being used for.Tides are caused by the gravitational pull of the sun and the moon on the ocean. They are regular and predictable and they produce less intermittent energy than wind or solar power. Check out NASA’s visualization of the earth surface currents:
REAC recently completed testing the StreamCube in Orkney with the help of international marine contractors, Leask Marine. This location, off the north coast of Scotland, has become a hot-spot for testing wave and tidal devices. This is because of the many natural tidal currents around the archipelago and its connection to the Scottish grid.
“Our successful testing operations in Orkney has been a further important learning exercise in de-risking and improving the StreamCube to provide cost-efficient tidal energy solution to the market,” explained REAC’s Technical Director, Dr. Ing. Tobias Breitbach in an interview with Tidal Energy Today.
The results from the trial will help REAC finalize the full-scale prototype before it progresses towards commercialization. REAC claim their device has a low cost, is easily transportable and has little impact on the environment, amongst other benefits.
Whilst the costs of setting up a tidal power operation are high, once in place, operating costs are low. Research conducted in 2015 found that if you take into consideration construction, operation, and maintenance costs over a lifetime, the levelized cost of tidal energy works out to be around $225/MW h. This is more expensive than other traditional energy sources; however, as technology continues to improve, the costs of tidal energy will no doubt become more competitive.
If all of StreamCube’s benefits turn out to be true, this might be the turn of the tides for tidal energy. It’s exciting to see yet another innovation harnessing one of mother nature’s infinite resources. | <urn:uuid:0a6c1a2a-607a-4368-aa29-647cb447b932> | 3 | 624 | Truncated | Science & Tech. | 40.448063 | 95,556,569 |
Famine, economic collapse, a sun that cooks us: What climate change could wreak — sooner than you think.
[New York Magazine] It is, I promise, worse than you think. If your anxiety about global warming is dominated by fears of sea-level rise, you are barely scratching the surface of what terrors are possible, even within the lifetime of a teenager today. And yet the swelling seas — and the cities they will drown — have so dominated the picture of global warming, and so overwhelmed our capacity for climate panic, that they have occluded our perception of other threats, many much closer at hand. Rising oceans are bad, in fact very bad; but fleeing the coastline will not be enough.
Indeed, absent a significant adjustment to how billions of humans conduct their lives, parts of the Earth will likely become close to uninhabitable, and other parts horrifically inhospitable, as soon as the end of this century.
Even when we train our eyes on climate change, we are unable to comprehend its scope. This past winter, a string of days 60 and 70 degrees warmer than normal baked the North Pole, melting the permafrost that encased Norway’s Svalbard seed vault — a global food bank nicknamed “Doomsday,” designed to ensure that our agriculture survives any catastrophe, and which appeared to have been flooded by climate change less than ten years after being built.
The Doomsday vault is fine, for now: The structure has been secured and the seeds are safe. But treating the episode as a parable of impending flooding missed the more important news. Until recently, permafrost was not a major concern of climate scientists, because, as the name suggests, it was soil that stayed permanently frozen. But Arctic permafrost contains 1.8 trillion tons of carbon, more than twice as much as is currently suspended in the Earth’s atmosphere. When it thaws and is released, that carbon may evaporate as methane, which is 34 times as powerful a greenhouse-gas warming blanket as carbon dioxide when judged on the timescale of a century; when judged on the timescale of two decades, it is 86 times as powerful. In other words, we have, trapped in Arctic permafrost, twice as much carbon as is currently wrecking the atmosphere of the planet, all of it scheduled to be released at a date that keeps getting moved up, partially in the form of a gas that multiplies its warming power 86 times over. Read More | <urn:uuid:77b6c644-02dc-4997-b1ae-1eae9485d2b1> | 2.8125 | 512 | Personal Blog | Science & Tech. | 38.847358 | 95,556,573 |
Authors: George Rajna
The nickel-bismuth (Ni-Bi) sample studied here is the first example of a 2-D material where this type of superconductivity is intrinsic, meaning that it happens without the help of external agents, such as a nearby superconductor. collaborated to design, build and test two devices that utilize different superconducting materials and could make X-ray lasers more powerful, versatile, compact and durable. A team of researchers at the U.S. Department of Energy's (DOE) Argonne National Laboratory has identified a nickel oxide compound as an unconventional but promising candidate material for high-temperature superconductivity. An international team led by scientists from the Department of Energy's SLAC National Accelerator Laboratory and Stanford University has detected new features in the electronic behavior of a copper oxide material that may help explain why it becomes a perfect electrical conductor – a superconductor – at relatively high temperatures. An artistic representation of the data showing the breaking of spatial inversion and rotational symmetries in the pseudogap region of superconducting materials-evidence that the pseudogap is a distinct phase of matter. Superconductivity is a state in a material in which there is no resistance to electric current and all magnetic fields are expelled. This behavior arises from a so-called "macroscopic quantum state" where all the electrons in a material act in concert to move cooperatively through the material without energy loss. Harvard researchers found a way to transmit spin information through superconducting materials. Researchers at the National Institute of Information and Communications Technology, in collaboration with researchers at the Nippon Telegraph and Telephone Corporation and the Qatar Environment and Energy Research Institute have discovered qualitatively new states of a superconducting artificial atom dressed with virtual photons. A group of scientists from Moscow Institute of Physics and Technology and from the Moscow State University has developed a fundamentally new type of memory cell based on superconductors – this type of memory works hundreds of times faster than the memory devices commonly used today, according to an article published in the journal Applied Physics Letters. Superconductivity is a rare physical state in which matter is able to conduct electricity—maintain a flow of electrons—without any resistance. It can only be found in certain materials, and even then it can only be achieved under controlled conditions of low temperatures and high pressures. New research from a team including Carnegie's Elissaios Stavrou, Xiao-Jia Chen, and Alexander Goncharov hones in on the structural changes underlying superconductivity in iron arsenide compounds—those containing iron and arsenic. This paper explains the magnetic effect of the superconductive current from the observed effects of the accelerating electrons, causing naturally the experienced changes of the electric field potential along the electric wire. The accelerating electrons explain not only the Maxwell Equations and the Special Relativity, but the Heisenberg Uncertainty Relation, the wave particle duality and the electron's spin also, building the bridge between the Classical and Quantum Theories. The changing acceleration of the electrons explains the created negative electric field of the magnetic induction, the Higgs Field, the changing Relativistic Mass and the Gravitational Force, giving a Unified Theory of the physical forces. Taking into account the Planck Distribution Law of the electromagnetic oscillators also, we can explain the electron/proton mass rate and the Weak and Strong Interactions.
Comments: 29 Pages.
[v1] 2017-06-26 07:13:48
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Vixra.org is a pre-print repository rather than a journal. Articles hosted may not yet have been verified by peer-review and should be treated as preliminary. In particular, anything that appears to include financial or legal advice or proposed medical treatments should be treated with due caution. Vixra.org will not be responsible for any consequences of actions that result from any form of use of any documents on this website.
Add your own feedback and questions here:
You are equally welcome to be positive or negative about any paper but please be polite. If you are being critical you must mention at least one specific error, otherwise your comment will be deleted as unhelpful. | <urn:uuid:ea9a587d-5c3f-4aaa-881f-9990b0902121> | 3.25 | 870 | Knowledge Article | Science & Tech. | 14.740678 | 95,556,585 |
Authors: George Rajna
Multiplexing, the ability to send multiple signals through a single channel, is a fundamental feature of any voice or data communication system. Energy loss due to scattering from material defects is known to set limits on the performance of nearly all technologies that we employ for communications, timing, and navigation. An international collaborative of scientists has devised a method to control the number of optical solitons in microresonators, which underlie modern photonics. Solitary waves called solitons are one of nature's great curiosities: Unlike other waves, these lone wolf waves keep their energy and shape as they travel, instead of dissipating or dispersing as most other waves do. In a new paper in Physical Review Letters (PRL), a team of mathematicians, physicists and engineers tackles a famous, 50-year-old problem tied to these enigmatic entities. Theoretical physicists studying the behavior of ultra-cold atoms have discovered a new source of friction, dispensing with a century-old paradox in the process. Their prediction, which experimenters may soon try to verify, was reported recently in Physical Review Letters. Solitons are localized wave disturbances that propagate without changing shape, a result of a nonlinear interaction that compensates for wave packet dispersion. Individual solitons may collide, but a defining feature is that they pass through one another and emerge from the collision unaltered in shape, amplitude, or velocity, but with a new trajectory reflecting a discontinuous jump.
Comments: 25 Pages.
[v1] 2017-08-10 06:38:11
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Vixra.org is a pre-print repository rather than a journal. Articles hosted may not yet have been verified by peer-review and should be treated as preliminary. In particular, anything that appears to include financial or legal advice or proposed medical treatments should be treated with due caution. Vixra.org will not be responsible for any consequences of actions that result from any form of use of any documents on this website.
Add your own feedback and questions here:
You are equally welcome to be positive or negative about any paper but please be polite. If you are being critical you must mention at least one specific error, otherwise your comment will be deleted as unhelpful. | <urn:uuid:dac44100-f8b9-4013-a6f2-da8f42d4ff05> | 3.078125 | 480 | Knowledge Article | Science & Tech. | 26.603003 | 95,556,586 |
Trolina McGrath: How Pollution Changing the Ocean's Chemistry
Subtitles and Transcript
How pollution is changing the ocean's chemistry
0:12 Do you ever think about how important the oceans are in our daily lives? The oceans cover two-thirds of our
planet. They provide half the oxygen we breathe. They moderate our climate. And they provide jobs and medicine
and food including 20 percent of protein to feed the entire world population. People used to think that the oceans
were so vast that they wouldn't be affected by human activities.
0:43 Well today I'm going to tell you about a serious reality that is changing our oceans called ocean acidification, or
the evil twin of climate change. Did you know that the oceans have absorbed 25 percent of all of the carbon dioxide
that we have emitted to the atmosphere? Now this is just another great service provided by the oceans since
carbon dioxide is one of the greenhouse gases that's causing climate change. But as we keep pumping more and
more and more carbon dioxide into the atmosphere more is dissolving into the oceans. And this is what's changing
our ocean chemistry. When carbon dioxide dissolves in seawater, it undergoes a number of chemical reactions.
1:31 Now lucky for you, I don't have time to get into the details of the chemistry for today. But I'll tell you as more
carbon dioxide enters the ocean, the seawater pH goes down. And this basically means that there is an increase in
ocean acidity. And this whole process is called ocean acidification. And it's happening alongside climate change.
Scientists have been monitoring ocean acidification for over two decades. This figure is an important time series in
Hawaii, and the top line shows steadily increasing concentrations of carbon dioxide, or CO2 gas, in the atmosphere.
And this is directly as a result of human activities. The line underneath shows the increasing concentrations of
carbon dioxide that is dissolved in the surface of the ocean which you can see is increasing at the same rate as
carbon dioxide in the atmosphere since measurements began. The line on the bottom shows then shows the
change in chemistry. As more carbon dioxide has entered the ocean, the seawater pH has gone down, which
basically means there has been an increase in ocean acidity. Now in Ireland, scientists are also monitoring ocean
acidification — scientists at the Marine Institute and NUI Galway. And we, too, are seeing acidification at the same
rate as these main ocean time-series sites around the world. So it's happening right at our doorstep.
3:00 Now I'd like to give you an example of just how we collect our data to monitor a changing ocean. Firstly we
collect a lot of our samples in the middle of winter. So as you can imagine, in the North Atlantic we get hit with some
seriously stormy conditions — so not for any of you who get a little motion sickness, but we are collecting some very
valuable data. So we lower this instrument over the side of the ship, and there are sensors that are mounted on the
bottom that can tell us information about the surrounding water, such as temperature or dissolved oxygen. And then
we can collect our seawater samples in these large bottles. So we start at the bottom, which can be over four
kilometers deep just off our continental shelf, and we take samples at regular intervals right up to the surface. We
take the seawater back on the deck, and then we can either analyze them on the ship or back in the laboratory for
the different chemicals parameters.
3:52 But why should we care? How is ocean acidification going to affect all of us? Well, here are the worrying facts.
There has already been an increase in ocean acidity of 26 percent since pre-industrial times, which is directly due to
human activities. Unless we can start slowing down our carbon dioxide emissions, we're expecting an increase in
ocean acidity of 170 percent by the end of this century. I mean this is within our children's lifetime. This rate of
acidification is 10 times faster than any acidification in our oceans for over 55 million years. So our marine life have
never, ever experienced such a fast rate of change before. So we literally could not know how they're going to cope.
4:58 Now there was a natural acidification event millions of years ago, which was much slower than what we're
seeing today. And this coincided with a mass extinction of many marine species. So is that what we're headed for?
Well, maybe. Studies are showing some species are actually doing quite well but many are showing a negative
response. One of the big concerns is as ocean acidity increases, the concentration of carbonate ions in seawater
decrease. Now these ions are basically the building blocks for many marine species to make their shells, for
example crabs or mussels, oysters.
5:44 Another example are corals. They also need these carbonate ions in seawater to make their coral structure in
order to build coral reefs. As ocean acidity increases and the concentration of carbonate ions decrease, these
species first find it more difficult to make their shells. And at even even lower levels, they can actually begin to
6:11 This here is a pteropod, it's called a sea butterfly. And it's an important food source in the ocean for many
species, from krill to salmon right up to whales. The shell of the pteropod was placed into seawater at a pH that
we're expecting by the end of this century. After only 45 days at this very realistic pH, you can see the shell has
almost completely dissolved. So ocean acidification could affect right up through the food chain — and right onto our
dinner plates. I mean who here likes shellfish? Or salmon? Or many other fish species whose food source in the
ocean could be affected?
6:57 These are cold-water corals. And did you know we actually have cold-water corals in Irish waters, just off our
continental shelf? And they support rich biodiversity, including some very important fisheries. It's projected that by
the end of this century, 70 percent of all known cold-water corals in the entire ocean will be surrounded by seawater
that is dissolving their coral structure. The last example I have are these healthy tropical corals. They were placed in
seawater at a pH we're expecting by the year 2100. After six months, the coral has almost completely dissolved.
Now coral reefs support 25 percent of all marine life in the entire ocean. All marine life.
7:57 So you can see: ocean acidification is a global threat. I have an eight-month-old baby boy. Unless we start now
to slow this down, I dread to think what our oceans will look like when he's a grown man. We will see acidification.
We have already put too much carbon dioxide into the atmosphere. But we can slow this down. We can prevent the
worst-case scenario. The only way of doing that is by reducing our carbon dioxide emissions. This is important for
both you and I, for industry, for governments.
8:40 We need to work together, slow down global warming slow down ocean acidification and help to maintain a
healthy ocean and a healthy planet for our generation and for generations to come. | <urn:uuid:204b38ad-42e3-49b8-8017-434d0147f4fd> | 3.21875 | 1,558 | Audio Transcript | Science & Tech. | 53.444646 | 95,556,593 |
Whooping CraneLatin name: Grus Americana,
Conservsation status: endangered (population is increasing)
The tallest bird in North America, the Whooping Crane is able to fly 500 miles a day. Some young cranes hatched in captivity learned their migration routes by following ultralight air craft.
Before 1800 there were an estimated 10–20,000 Whooping Cranes in North America. By 1941, because of hunting and habitat destruction, there were fewer than 20. There are now approximately 350–380 in the wild. The wild Whooping Crane population has only one winter habitat—a wildlife refuge on the Gulf Coast in Texas; and one spring breeding habitat—a prairie wetlands in Alberta. Severe storms, sea level rise, drought, industrial development and oil spills threaten these habitats. Another significant threat to young Whooping Cranes is colliding with power lines in their migration corridor.
Other animals at risk
All populations of Ringed Seals are expected to be adversely affected by climate change because of dependence on sea ice and snow dens for breeding, protecting pups, moulting and resting. Early warming causes pups to separate prematurely from their mothers. As sea ice declines, other threats are fisheries by-catch, increased shipping, tourism and development. Seals are vulnerable to disease from heavy concentrations of pollutants that have accumulated in the Arctic food web.
Polar Bears live only in the Arctic. Loss of sea ice has a critically adverse effect on Polar Bears. They hunt from the edge and build snow dens on the ice for resting and raising their cubs. Sea ice decline could open the Arctic to shipping and tourism, further disturbing Arctic habitats. Other threats are oil development and industrial pollution that reaches the Arctic through air and ocean currents.
The Narwhal lives mainly in the Atlantic Arctic. Because of specialized habitat, narrow range and limited diet (Arctic cod and halibut), it is one of the Arctic species most vulnerable to climate change. The Narwhal breeds in bays and fjords, moving offshore during winter to areas of heavy ice pack, breathing through the few cracks. Sudden or extreme temperature change can cause these cracks to freeze shut, trapping the whales. Other threats are illegal hunting, industrial activities, and risks from oil development, exploration and shipping in the Arctic.
Ivory Gulls are almost entirely dependent on sea ice and glaciers for nesting and food foraging. They feed on fish and shellfish that thrive near the edge of the ice, and on the remains of seals left by Polar Bears. Seal blubber is a source of heavy contaminants—Ivory Gull eggs show a higher concentration of mercury and pesticides than any Arctic sea bird. Other threats are illegal hunting and disturbance from diamond mining in the Canadian Arctic. | <urn:uuid:e959510e-db61-4f60-9a66-887ef91860d6> | 3.796875 | 567 | Knowledge Article | Science & Tech. | 38.867692 | 95,556,604 |
According to a study published in the journal Nature, hurricanes in the Atlantic are more frequent than at any time in the last 1,000 years and could get worse due to global warming.
Scientists made their calculation by examining sediments left by hurricanes that crossed the coast in North America and the Caribbean, the journal says, The USA Today reports.
The study's lead author, climate scientist Michael Mann of Pennsylvania State University, said finding a reliable way to reconstruct centuries of past hurricane activity could help scientists tease out whether future climate change will alter storm patterns.
"One of the driving motivations for this research is to place in a longer-term context ... Atlantic tropical cyclone behavior, and the extent to which it may be anomalous," he said.
That meant trying to divine information about the past beyond historical records collected by ships and observers on shore, and later by storm-tracking aircraft and satellite, The New York Times reports.
An average of 17 hurricans and tropical storms hit the Atlantic in the last decade, which is more than twice the number recorded earlier in the century.
However, there may have been more storms 1,000 years ago than in modern times. Current levels were matched, and may have been exceeded, during the Medieval Climate Anomaly about 1,000 years ago.
Dr. Mann says the circumstances forming the high hurricane activity now are different than 1,000 years ago.
“Even though the levels of activity are similar [between 1,000 years ago and now], the factors behind that are different,” Dr Mann told BBC News.
“The implication is that if everything else is equal — and we don’t know that about El Nino — then warming of the tropical Atlantic should lead to
increasing levels of Atlantic tropical cyclone activity.”
The high number now is spurred by warming waters in the Atlantic Ocean, expected to increase even further in coming years, The National Post reports.
A US-based TV channel named curious details about the trials of the new Russian missile, such as, for example, the failed launch in October 2017
Russian President Vladimir Putin expressed his opinion regarding the controversial pension reform in Russia
The International Olympic Committee is ready to take Russia back, the head of the organization Thomas Bach said | <urn:uuid:11a88e14-2bb2-49d0-8764-d4eb7ef651b6> | 3.40625 | 463 | News Article | Science & Tech. | 37.95 | 95,556,622 |
Volcanic 'tunnels' detected on Mars could offer a safe haven for life - and might even offer shelter for astronauts
- Collapsed lava tubes indicate there may be caves under Martian surface
- Caves could 'shield' microbes from radiation 250 times higher than Earth's
- Could be refuge for future missions to Mars
Underground lava flows on Mars have carved out channels beneath the surface - and the long-dead volcanoes have left a network of tunnels in which life could thrive.
Distinctive 'pit chains' on the surface of Mars surround the Tharsus Montes volcanoes on the Red Planet - showing that tunnels and cavities have collapsed after the lava flows ceased.
Scientists now believe that remaining tunnels - which may have had running water in their million-year-history - could be tempting targets in the search for microbial life on the Planet.
The distinctive markings are thought to have formed when underground lava flows carved out tunnels which then collapsed
Topographic map showing the elevations of the markings on the surface
The markings are found next to huge volcanoes on the Martian surface
The thin atmosphere of Mars means that the planet is blasted with 250 times more radiation than Earth - so life on the surface is unlikely.
Subterranean tubes, protected from the deadly rays, could provide a 'haven' for life - particularly if water was present.
Mars landers have measured surface
radiation around 250 times higher than that found on the Earth, and more
than double that experienced by astronauts on board the International
Any caves associated with the
pit-chains may in future provide a possible refuge for astronauts from
the harsh surface radiation.
The tubes were detected in images released from European Space Agency’s Mars Express orbiter, revealing a series of ‘pit-chains’ on the flanks of one of the largest volcanoes in the Solar System.
The images, taken on 22 June 2011, cover Tractus Catena in the Arcadia quadrangle, part of the vast Tharsis region on Mars.
This region boasts a number of huge volcanoes, including the three collectively known as Tharsis Montes. To their north sits Alba Mons, also known as Alba Patera, one of the largest volcanoes in the Solar System by area and volume.
Pit-chains can have a volcanic origin. Lava streaming from a volcano solidifies on the surface, leaving a molten tube of lava running below.
The collapsed tunnels indicate there might be undgerground areas which still exist - and which could offer a haven for microbial life
Once volcanic activity ceases, the tube empties, leaving behind a subterranean cavity. Over time, parts of the roof over the cavity may collapse, leaving circular depressions on the surface.
On Earth, recent examples can be seen on the flanks of Kilauea volcano in Hawaii, while on the Moon, Hadley Rille, visited by Apollo 15 in 1971, is believed to have formed in the same way billions of years ago.
Another scenario for the creation of the unusual features involves groundwater.
On Earth, there are clear examples of similar structures in ‘Karst’ regions – after the German name for a region extending from Slovenia to Italy, where this phenomenon was first studied.
Some of Earth’s most famous examples are the network of ‘cenotes’ on the Yucatan peninsula of Mexico. These deep natural pits form when the surface limestone rocks collapse, exposing the groundwater underneath.
This origin is the most interesting in the context of the search for microbial life on Mars. If there are any cave-like structures associated with the pits, microorganisms could have survived, protected from the harsh surface environment.
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Intensifying winds in the Southern Ocean have had little influence on the strength of the Southern Ocean circulation and therefore its ability to absorb carbon dioxide from the atmosphere, according to a study published in Nature Geoscience.
The Southern Ocean slows the rate of greenhouse warming by removing carbon dioxide from the atmosphere and storing it in the ocean. But previous studies raised the alarm by suggesting the Southern Ocean carbon sink is now 'saturated' and no longer able to keep pace with increasing concentrations of carbon dioxide in the atmosphere.
The new study suggests that Southern Ocean currents, and therefore the Southern Ocean's ability to soak up carbon dioxide, have not changed in recent decades, despite a large increase in winds.
A team of German and Australian scientists compared new ocean measurements from a global network of ocean robots with historical data from ships to determine if the Southern Ocean was changing. The study was led by Professor Claus Böning from the Institute of Marine Research (IFM-GEOMAR), Kiel.
Co-author, CSIRO's Dr Steve Rintoul, says the Southern Ocean was found to have become warmer and fresher since the 1960s – a pattern consistent with the 'fingerprint' of climate change caused by carbon emissions from human activity.
"But, counter to our expectations, other aspects of the Southern Ocean have not changed despite the increase in winds," he says. "In particular, we found no evidence of a change in strength of the ocean currents that circle around Antarctica, or in the amount of deep water rising to the surface near Antarctica."
The fact that the upwelling of deep water has not changed is important. Deep water is very rich in carbon dioxide and so an increase in upwelling tends to transfer carbon dioxide from the ocean to the atmosphere. The low-resolution models used for climate forecasts predict stronger winds, which cause stronger upwelling and therefore less carbon dioxide being stored in the ocean.
"Our results suggest that the small-scale motions of ocean eddies act to balance the stronger winds, with no change in upwelling," Dr Rintoul says. "Climate models in use today cannot represent these small-scale motions and so over-estimate the response of the Southern Ocean to changes in winds." Dr Rintoul works through the Antarctic Climate and Ecosystem Cooperative Research Centre (ACECRC) and CSIRO's Wealth from Oceans Flagship.
Integral to the research was the Australian ocean data archive and the Argo network of ocean profilers. The data provided by the global array of more than 3,100 Argo floats is particularly valuable in remote areas like the sparsely-sampled Southern Ocean.
Source: CSIRO Australia
Explore further: Stronger west winds blow ill wind for climate change | <urn:uuid:fba994d7-21ad-4437-b278-aa68f1d99753> | 3.734375 | 561 | News Article | Science & Tech. | 32.172277 | 95,556,638 |
Issues: Code Generation
Again Freestudy9 comes with new post related to the Issues: Code Generation. Additionally, we had described it as a point to point information.
Issues in the Design of Code Generator
1. An input to the Code Generator
- An input to the code generator consists of the intermediate representation of the source program.
- Moreover, There are several types of the intermediate language, such as postfix notation, quadruples, and syntax trees or DAGs.
- So, The detection of semantic error should be done before submitting the input to the code submitting generator.
- The code generation phase require complete error-free intermediate code as an input.requires
2. Target program
- The output of the code generator is the target program. The output may take on a variety of forms; absolute machine language, relocatable machine language, or assembly language, language.
- Producing an absolute machine language program as output has the advantage that it can be placed in a location in memory and immediately executed.
- Producing a relocatable machine language program as output is that the subroutine can be compiled separately. A set of relocatable object modules can link together and loaded for execution by a linking loader.
- Similarly, Producing an assembly language program as output makes the process of code generation somewhat easier. We can generate symbolic instructions and use the macro what facilities of the assembler to help generate core.
3. Memory management
- Mapping names in the source program to addresses of data objects in run-time memory are done cooperatively by the front end and the code generator.
- So that We assume that a name in a three-address statement refers to a symbol table entry for three-address the name.
- From the symbol table information, a relative address can determine for the name bol
in a data area.
4. Instruction selection
- If we do not care about the efficiency of the target program, instruction selection is straightforward. It requires special handling. So that, For example, the sequence of statement example,
a := b + c
d := a + e
would be translated into
MOV b, R0
ADD c, R0
MOV R0, a
MOV a, R0
ADD e, R0
MOV R0, d
- So, Here the fourth statement is redundant, so we can eliminate that statement.
5. Register allocation Issues: Code Generation
- If the instruction contains register operands then such a use becomes shorter and faster than that of using in memory.
- Moreover, The use of registers often subdivided into two subproblems:
- During register allocation, we select the set of variables that will reside in registers at a point in the program.
- During a subsequent register assignment phase, we pick the specific register that a variable will reside in.
- Finding an optimal assignment of registers to variables is difficult, even with single register value.
- Mathematically the problem is NP-complete.
6. Choice of evaluation Issues: Code Generation
- The order in which computations performed can affect the efficiency of the target code. Some computation orders require fewer registers to hold intermediate results than others. Picking the best order is another difficult, NP-complete problem, and NP-complete
7. Approaches to code generation Issues: Code Generation
- Similarly, The most important criterion for a code generator is that it produces correct code.
- Correctness takes on special significance because of the number of special cases that code generator must face.
- Given the premium on correctness, designing a code generator so it can easily implement, tested, and maintained is an important design goal. | <urn:uuid:d0255d5e-5481-45be-ac89-f0508eaa2cf7> | 3.140625 | 769 | Documentation | Software Dev. | 29.705047 | 95,556,647 |
"It’s impossible to miss when the seasons change. But do most people understand the science behind those changes? According to decades-old research by astronomers and educators at the Harvard-Smithsonian Center for Astrophysics (CfA), probably not."
"Somewhere in the neighborhood of the red dwarf star Proxima Centauri—4.25 light years from Cambridge—a small, hyper-reflective spacecraft will home in on an unfamiliar planet." Full article in the Harvard Crimson
For thousands of years, humans have searched for a way to turn matter into gold. Ancient alchemists considered this precious metal to be the highest form of matter. As human knowledge advanced, the mystical aspects of alchemy gave way to the sciences we know today. And yet, with all our advances in science and technology, the origin story of gold remained unknown. Until now.
Marking the beginning of a new era in astrophysics, scientists have detected gravitational waves and electromagnetic radiation, or light, from the same event for the first time. This historic discovery reveals the merger of two neutron stars, the dense cores of dead stars, and resolves the debate about how the heaviest elements such as platinum and gold were created in the Universe.
First Prototype ‘Sprites’ – Precursors to Eventual ‘StarChip’ Probes – Achieve Low Earth Orbit
San Francisco – July 26, 2017 – Breakthrough Starshot, a multi-faceted program to develop and launch practical interstellar space missions, successfully flew its first spacecraft – the smallest ever launched.
On June 23, a number of prototype “Sprites” – the world’s smallest fully functional space probes, built on a single circuit board – achieved Low Earth Orbit, piggybacking on OHB...
"The world's most indestructible species, the tardigrade, an eight-legged micro-animal, also known as the water bear, will survive until the Sun dies, according to a new Oxford University collaboration."
"The new study published in Scientific Reports, has shown that the tiny creatures, will survive the risk of extinction from all astrophysical catastrophes, and be around for at least 10 billion years – far longer than the human race."
Evolver social movement & the Hive to Thrive speaker series hosted Harvard University director of astronomy Avi Loeb for a wide ranging discussion. From the nature of scientific discovery to possible origins of FRBs (Fast Radio Bursts) emanating from the cosmic background radio noise. Produced...
"An Earth-sized planet next door: that was the startling announcement last August. Astronomers had found an exoplanet orbiting the sun’s closest stellar neigh- bor, a cool red dwarf star called Proxima Centauri (1). Even better, the nearby world orbited within its parent star’s habitable zone, meaning liquid water could exist on the planet’s surface, which raised the prospects for its harboring life."
All eyes on Proxima Centauri b: http://www.pnas.org/content/114/26/6646.full.pdf
I am very sorry to report that our colleague Pat Thaddeus passed away this morning.
Pat was a highly influential teacher and astronomer for over 50 years, including the past 30 at the CfA. His interests were extremely broad, including pioneering work on the cosmic microwave background radiation, planetary atmospheres, and large-scale studies of star formation and galactic structure. He was one of the founders of the now flourishing field of astrochemistry. His elegant laboratory spectroscopy provided ironclad identifications of... | <urn:uuid:74908c9e-c2d3-4105-86b9-61554af9cf79> | 3.328125 | 751 | Content Listing | Science & Tech. | 43.1746 | 95,556,662 |
In what sounds like the stuff nightmares are made of, a Chinese facility is breeding roaches by the billions for use in medicinal concoctions. These “healing potions” are reportedly use to cure respiratory, gastric, and other diseases according to an official report.
As South China Morning Post reporter Stephen Chen tells it:
Long, narrowly spaced rows of shelves fill a multi-storey building about the size of two sports fields. The shelves are lined with open containers of food and water.
It is warm, humid and dark all year round, with freedom to roam to find food and reproduce. Fully sealed like a prison, it has strict limitations on access to visitors. From birth to death, inhabitants never see the sun.
Do you want to be a cryptocurrency millionaire?
Don't get your hopes up.
What Chen describes sounds a bit like a roach-led version of The Matrix, but it is in fact a breeding facility responsible for producing more than six billion adult cockroaches each year.
This building is one of many. In Sichuan alone, government officials report producing nearly 28,000 full-sized adult cockroaches per square foot, each year, in similar facilities.
Each facility relies on AI to continually collect and analyze more than 80 categories of data. These include humidity, temperature, food supply and consumption, as well as genetic mutations and modeling future growth.
This is important data for a country where more than 40 million people consume crushed-up roach concoctions due to their perceived health benefits. (In case you’re wondering — which you almost certainly are not — it’s reported that the roach potions look like tea, have a bit of a fishy smell, and taste slightly sweet.)
But if roach tea has you grossed out, you might want to skip this next part entirely.
According to Professor Zhu Chaodong of the Institute of Zoology at the Chinese Academy of Science, if the roaches were to escape — whether by human error or natural disaster — the results would be “catastrophic.” Just a dozen of them could infest an entire neighborhood, he says.
Worse, some critics are concerned that amplified reproduction and genetic screening could accelerate the natural evolution of the insect, thus producing “super cockroaches” of abnormal size and breeding capability.
“Multiple lines of defence must be in place and work properly to prevent the disaster of accidental release,” Zhu continued. | <urn:uuid:a5708947-4819-4923-a3b3-b726d103a8b2> | 2.625 | 513 | News Article | Science & Tech. | 41.03508 | 95,556,697 |
Alkanes are the organic compounds that consist of single-bonded carbon and hydrogen atoms. The formula for Alkanes is CnH2n+2CnH2n+2, subdivided into three groups – chain alkanes, cycloalkanes, and the branched alkanes.These are comprised of a series of compounds that contain carbon and hydrogen atoms with single covalent bonds.This group of compounds consists of carbon and hydrogen atoms with single covalent bonds. Also, comprises of a homologous series having a molecular formula of C n H 2 n+2
Read about Physical Properties of Alkanes Group.
The simple alkane methane contains one carbon atom and CH 4 as its molecular formula. As this compound have just single covalent bonds only, therefore, its structural formula is
In a long chain alkane molecule, additional carbon atoms are attached to each other with the help of a single covalent bond. Each atom is attached to the sufficient hydrogen atoms to develop a total of four single covalent bonds. This long chain structure is known as octane. An eight-carbon alkane has a molecular formula – C 8H 18 and structural formula-
When a substituent like halogen bonds to an alkane molecule, one carbon-hydrogen bond of the molecule gets converted to carbon-substituent bond. It can be understood with an example- A new compound known as chloromethane is formed when methane reacts with chlorine. The new compound is composed of CH 3 group that is bonded to a chlorine atom.
When an alkane having hydrogen is removed from one bond, it is called an alkyl group. This Alkyl group is often denoted by the letter R same as halogens represent by the letter X. Here is methane‐chlorine reaction that can be generalized as
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As many Asian countries prepare to celebrate Year of the Tiger beginning February 14, World Wildlife Fund (WWF) reports that tigers are in crisis around the world, including here in the United States, where more tigers are kept in captivity than are alive in the wild throughout Asia.
As few as 3,200 tigers exist in the wild in Asia where they are threatened by poaching, habitat loss, illegal trafficking and the conversion of forests for infrastructure and plantations.
WWF is releasing a new interactive map of the world’s top 10 tiger trouble spots and the main threats against tigers. WWF is also launching a campaign: Tx2: Double or Nothing to support tiger range states in their goal of doubling wild tiger numbers by the next Year of the Tiger in 2022.
The issues highlighted in the trouble spots map (www.worldwildlife.org/troublespots) include:
Pulp, paper, palm oil and rubber companies are devastating the forests of Indonesia and Malaysia, home to two endangered tiger sub-species;
Hundreds of new or proposed dams and roads in the Mekong region will fragment tiger habitat;
Illegal trafficking in tiger bones, skins and meat feeds a continued demand in East and Southeast Asia;
More tigers are kept in captivity in the U.S. than are left in the wild -- and there are few regulations to keep these tigers from ending up on the black market. The largest numbers of captive tigers are in Texas (an estimated 3,000+), but they are also kept in other states;
Poaching of tigers and their prey, along with a major increase in logging is taking a heavy toll on Amur, or Siberian, tigers;
Tigers and humans are increasingly coming into conflict in India as tiger habitats shrink;
Climate change could reduce tiger habitat in Bangladesh’s Sundarbans mangroves by 96 percent.
Three tiger sub-species have gone extinct since the 1940s and a fourth one, the South China tiger, has not been seen in the wild in 25 years. Tigers occupy just seven percent of their historic range. But they can thrive if they have strong protection from poaching and habitat loss and enough prey to eat.
"Tigers are being persecuted across their range – poisoned, trapped, snared, shot and squeezed out of their homes," said Mike Baltzer, Leader of WWF’s Tiger Initiative. "But there is hope for them in this Year of the Tiger. There has never been such a committed, ambitious, high-level commitment from governments to double wild tiger numbers. They have set the bar high and we hope for the sake of tigers and people that they reach it."
In the U.S., the government does not track how many tigers are in captivity within its borders, where they are, who owns them, or what happens to their body parts when they die. In many states, there are no controls on individuals keeping tigers as pets. Current estimates indicate that there are more than 5,000 tigers in captivity in the United States, more than exist in the wild. A registration scheme for all captive tigers and a means to monitor disposal of dead tigers is urgently needed to ensure they aren’t exploited for the illegal trade.
In the lead up to the Vladivostok Summit, all 13 tiger range countries recently committed to the goal of doubling tiger numbers by 2022 at a ministerial meeting in Hua Hin, Thailand. They will be helped in this goal by WWF and other members of the Global Tiger Initiative. The Summit will be co-hosted by Russian Prime Minister Vladimir Putin and World Bank President Robert Zoellick.
"We may not get another opportunity like this with so much political will from the tiger range countries and attention from so many institutions and people around the world," said Sybille Klenzendorf, Director of the WWF-US Species Program. "The situation for tigers is a sobering one, but if we seize this moment and maintain it for the long term, the next Year of the Tiger may give us real reason to celebrate."
Lee Poston | EurekAlert!
Upcycling of PET Bottles: New Ideas for Resource Cycles in Germany
25.06.2018 | Fraunhofer-Institut für Betriebsfestigkeit und Systemzuverlässigkeit LBF
Dry landscapes can increase disease transmission
20.06.2018 | Forschungsverbund Berlin e.V.
A new manufacturing technique uses a process similar to newspaper printing to form smoother and more flexible metals for making ultrafast electronic devices.
The low-cost process, developed by Purdue University researchers, combines tools already used in industry for manufacturing metals on a large scale, but uses...
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
13.07.2018 | Event News
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03.07.2018 | Event News
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Geography professor Bruce Rhoads and geology professor Jim Best were conducting research where the Wabash River meets the Ohio River in the summer of 2008 when they heard about a new channel that had just formed, cutting off a bend in the winding Wabash just upstream from the confluence. That serendipity gave the researchers a rare view of a dynamic, little-understood river process that changed the local landscape and deposited so much sediment into the river system that it closed the Ohio River.
“It was fortunate to be there right when it was beginning to happen, because these are hard-to-predict, unusual events, particularly on large rivers,” Rhoads said.
While cutoffs are common in meandering rivers, or rivers that wander across their floodplains, the conditions surrounding cutoff events are poorly understood. Most cutoffs are discovered long after they first develop. The Illinois team’s quick response to the 2008 Wabash cutoff, and witnessing of a second cutoff in the same bend a year later, allowed them to monitor the huge amounts of sediment the cutoffs released into the river. The researchers published their findings in the journal Nature Geoscience.
“Cutoffs occur in just about every meandering river on the face of the earth,” said Jessica Zinger, a graduate student and lead author of the paper. “Although it’s unusual to capture one like this, they are ubiquitous events, so it’s important to understand what happens when these cutoffs occur, why they occur when they do, and how they evolve after they occur.”
The two cutoffs, both 1 kilometer long, delivered about 6 million tons of sediment from the floodplain into the river – equivalent to 6.4 percent of the total annual sediment load of the entire Mississippi River basin (which the Wabash contributes to) – in a matter of days. It would take nearly 250 years of bank erosion to displace the same amount of sediment along the bend, had the cutoff not occurred. Such sediment pulses, as they are known, are more often associated with mountain rivers, rather than the relatively level landscape of rural Illinois.
“The first kilometer-long channel was cut in eight days, which is a phenomenal rate of erosion,” Best said. “There were banks collapsing, sediment moving; it’s probably one of the most dynamic river environments you’ll ever see, and you don’t expect that in lowland, flat-grade rivers.”
The researchers found that, after each cutoff, the majority of the sediment was deposited locally. In particular, a large percentage of the sediment accumulated where the Wabash joins the Ohio River. The new layer of sediment, up to 7 meters thick, raised the bed of the Ohio River and required dredging so that barges could continue to use the river.
The Wabash River study demonstrated that cutoffs can have large, immediate effects on sediment transport and deposition in a river – processes not accounted for in current models of meandering rivers.
“If we look at river systems and their role in the landscape, one of their most fundamental roles from a geoscience perspective is that they transport sediment from the land surfaces to ocean basins,” Rhoads said. “What has not been recognized is that these cutoff events can actually deliver large amounts of sediment to the river very rapidly. Then, the question is, since cutoffs are ubiquitous along a lot of meandering rivers, could this be something that we have not recognized fully as a major sediment delivery mechanism for all meandering rivers?”
The researchers plan to continue monitoring the cutoff and the areas just upstream and downstream to document how the cutoffs contribute to the river’s evolution. They anticipate that the river will abandon the bend and the first cutoff as more water is directed through the second cutoff, a more direct route for the river to flow. The abandoned bend will become a new wetland area, shaping the local ecology. The researchers will continue to measure and model changes in flow velocity, sediment transport and morphology in the river as the cutoff channel widens, providing valuable insight into cutoff effects and perhaps contributing to a model that could predict where such sediment pulses could occur.
“Our study brings attention to a whole range of elements – the basic science, the local effects, the ecological effects, the commercial effects – all from this one mechanism of channel change,” s said. “A lot of the meandering models that are out there treat cutoffs very schematically and they don’t deal with the processes that are occurring once a cutoff develops. I think that our work could really make people rethink that aspect of modeling the long-term evolution of meander bends.”
The National Science Foundation supported this work.
Liz Ahlberg | University of Illinois
New research calculates capacity of North American forests to sequester carbon
16.07.2018 | University of California - Santa Cruz
Scientists discover Earth's youngest banded iron formation in western China
12.07.2018 | University of Alberta
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
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Deduction is the process whereby we pass from a general statement to a particular case: the reverse procedure, from the particular to the general, is variously called induction, or inference. Statistical inference is ordinarily understood to involve repetition or averaging, as when an inference is made about a population on the basis of a sample drawn from it. Economic facts are typically established by means of statistical inference. Economists construct a model of the world and deduce from it implications for the real world. These are checked against the available data, leading to some degree of support for the model. Statistical inference is concerned with how this support should be calculated.
KeywordsLoss Function Statistical Inference Bayesian Approach Interval Estimate Nuisance Parameter
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- De Finetti, B. 1974–5. Theory of Probability: a Critical Introductory Treatment. 2 vols, London: Wiley. Translation from the 1970 Italian original by A. Machi and A. Smith.Google Scholar
- Fisher, R.A. 1925. Statistical Methods for Research Workers. Edinburgh: Oliver & Boyd; 12 edn, New York: Hafner Publishing Co., 1954.Google Scholar
- Fisher, R.A. 1935. The Design of Experiments. Edinburgh: Oliver & Boyd; 6th edn, New York: Hafner Publishing Co., 1953.Google Scholar
- Lehmann, E.L. 1959. Testing Statistical Hypotheses. New York: Wiley.Google Scholar
- Ramsey, F.P. 1931. The Foundations of Mathematics and Other Logical Essays. London: Kegan, Paul, Trench, Trubner; New York: Humanities Press, 1950.Google Scholar
- Savage, L.J. 1954. The Foundations of Statistics. New York: Wiley.Google Scholar | <urn:uuid:6008da00-7e97-43e8-86ce-eb2e9f7d8eb2> | 2.640625 | 379 | Truncated | Science & Tech. | 45.129333 | 95,556,788 |
posted by jeffrisa
A 0.052g sample of aluminium reacts with excess 6M HCL. A 48.3mL volume of hydrogen gas was collected over water at 22C and the pressure of the hydrogen gas was 751mmHg.calculate the aluminum percent purity in the sample.
What volume of hydrogen gas at STP is produced from the reaction of 0.044g of 98.0% pure aluminium with excess 6M HCl.
2Al + 6HCl ==> 2AlCl3 + 3H2
Look up vapor pressure H2O @ 22 C = and I've estimated 22 mm
Use PV = nRT to solve for mols H2 evolved.
For P you have
Ptotal = pH2 + pH2O
751 mm = pH2 + 22
Therefore, estimated pH2 = 751-22 = approx 729. Use that for P in the PV = nRT formula.
Remember T must be in kelvin; solve for n.
Using the coefficients in the balanced equation, convert mols H2 to mols Al.
Then g Al = mols Al x atomic mass Al.
%Al = (grams Al from calcn/0.052)*100 = ?%
This is just the reverse process from part A above. This should get you started.
mass Al = 0.044 x 0.98 = ?
Convert to mols H2 from the equation.
Convert mols H2 to volume remembering that 1 mol at STP occupies 22.4 L. | <urn:uuid:605669f1-7977-4bef-8e0a-c1c98da2c232> | 2.671875 | 329 | Q&A Forum | Science & Tech. | 97.848676 | 95,556,794 |
posted by Jan
The table below shows how the braking distance x for a car depends on its initial speed u
u / ms-1 5.0 10 20 4
x / m 2.0 8.0 32 128
the reaction time of a driver is 0.60s. Calculate the sopping distance of the car when u= 30ms-1.
The mark scheme says:
Thinking distance= 30 X 0.6 =18m which I understand fully.
BRAKING DISTANCE =0.08 * U^2= 0.08 * 30^2= 72m IS THE BIT I DON’T UNDERSTAND. CAN SOMEONE PLEASE EXPALIN THE BRAKING DISTANCE STAGE AND WHY AND HOW YOU DO THIS BIT AS WELL AS ALL EQUATIONS INVOLVED!
Stopping distance= 18 +72= 90m which I understand fully.
Explain the working out of the braking distance for this question.
As physics - cylinder Thursday, November 9, 2017 at 7:37am
I wrote what I do know and the caps lock is what I dont know, and that is the working out for braking distance shown above is confusing to me.
As physics - Damon Thursday, November 9, 2017 at 8:39am
your table makes no sense to me
v = Vi + a t where t is AFTER 0.6 s
v = 30 + a t
x = Xi + Vi t + (1/2) a t^2
a will be negative of course
Xi is 18 when t = 0
x = 18 + 30 t + (1/2) a t^2
remember total stopping time = t + .6
As physics - cylinder Thursday, November 9, 2017 at 9:27am
I am in as and we dont use those symbols so im confused
Sorry for the repost i didnt understand and i just wanted to show how the working and answer went so someone can better help me
I had this question too and didnt understand it either when i went through thisquestionin a level we dont usae Xi or any of those please write in ful lsentencs ad clearly explain | <urn:uuid:35b4457e-aa88-43cb-a05d-66e33af080b1> | 3.296875 | 454 | Q&A Forum | Science & Tech. | 89.364739 | 95,556,795 |
The research, which appears in Proceedings of the National Academy of Sciences, was conducted by a multi-national team of scientists, including physicists at New York University, Princeton University, and the Max Planck Institute for Solar System Research.
Image courtesy of MPI for Solar System Research/Mark A. Garlick (www.markgarlick.com).
An artistic rendering of HD 52265 and its orbiting Jupiter-like planet.
The researchers examined HD 52265—a star approximately 92 light years away and nearly 20 percent more massive than our Sun. More than a decade ago, scientists identified an exopanet—a planet outside our Solar System—in the star’s orbit. HD 52265, then, served as an ideal model for both measuring stars’ properties and how such properties can shed light on planetary systems.
Previously, scientists inferred stars’ properties, such as radius, mass, and age, by considering observations of their brightness and color. Often these stars’ properties were not known to sufficient accuracy to further characterize the nearby planets.
In the PNAS study, the scientists adopted a new approach to characterize star-planet systems: asteroseismology, which identifies the internal properties of stars by measuring their surface oscillations. Some have compared this approach to seismologists’ use of earthquake oscillations to examine the earth’s interior.
Here, they were able to make several assessments of the star’s traits, including its mass, radius, age, and—for the first time— internal rotation. They used the COROT space telescope, part of a space mission led by the French Space Agency (CNES) in conjunction with the European Space Agency (ESA), to detect tiny fluctuations in the intensity of starlight caused by starquakes. The researchers confirmed the validity of the seismic results by comparing them with independent measurements of related phenomena. These included the motion of dark spots on the star’s surface and the star’s spectroscopic rotational velocity.
Unlike other methods, the technique of asteroseismology returns both the rotation period of the star and the inclination of the rotation axis to the line of sight.
The scientists could then use these findings to make a more definitive determination of an orbiting exoplanet. While it had previously been identified as an exoplanet by other scientists, some raised doubts about this conclusion, positing that it could actually be a brown dwarf—an object too small to be a star and too large to be a planet.
But, armed with the precise calculations yielded by asteroseismology, the researchers on the PNAS study were able to enhance the certainty of the earlier conclusion. Specifically, given the inclination of the rotation axis of HD 52265 and the minimum mass of the nearby exoplanet, the researchers could infer the true mass of the latter—which was calculated to be roughly twice that of our planet Jupiter and therefore too small to be a brown dwarf.
The study’s authors included: Katepalli Sreenivasan, president of Polytechnic Institute of NYU and dean of engineering at NYU; Shravan Hanasoge, an associate research scholar in geosciences at Princeton University and a visiting scholar at NYU’s Courant Institute of Mathematical Sciences; and Laurent Gizon, director of the Max Planck Institute for Solar System Research and a professor at the University of Goettingen in Germany.
James Devitt | Newswise
What happens when we heat the atomic lattice of a magnet all of a sudden?
18.07.2018 | Forschungsverbund Berlin
Subaru Telescope helps pinpoint origin of ultra-high energy neutrino
16.07.2018 | National Institutes of Natural Sciences
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
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12.07.2018 | Event News
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19.07.2018 | Earth Sciences
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What Do Black Holes Sound Like?
May 24, 2016
Janna Levin, professor of physics and astronomy at Barnard College and author of Black Hole Blues, describes the noise that black holes make this way: “You could say black holes are playing drums out there. Space-time is the drum, and black holes are the mallets.” The collision of two black holes, 30 times the mass of the sun and 1.3 billion light-years away, was captured by LIGO as a loud chirp. In this short video, Levin explains how scientists were able to record gravitational waves as sound waves and, for the first time ever, give space a "soundtrack."
We want to hear what you think. Submit a letter to the editor or write to firstname.lastname@example.org.
Authors: Caitlin Cadieux, Nicolas Pollock
About This Series
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By Ram Prasad
Fungal nanobiotechnology has emerged as one of many key applied sciences, and an green, as a resource of meals and harnessed to ferment and protect meals and drinks, in addition to purposes in human healthiness (antibiotics, anti-cholesterol statins, and immunosuppressive agents), whereas has used fungi for large-scale construction of enzymes, acids, biosurfactants, and to regulate fungal affliction in plants and pest keep watch over. With the harnessing of nanotechnology, fungi have grown more and more very important via supplying a greener substitute to chemically synthesized nanoparticles.
Read Online or Download Advances and Applications Through Fungal Nanobiotechnology (Fungal Biology) PDF
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"For the first time, we've been able to map this change in detail, and it's because of the spatial resolution and length-of-record that you can get with Landsat," says Jeff Masek, the program's project scientist. He's based at NASA's Goddard Space Flight Center in Greenbelt, Md.
Masek and his co-authors will present their study at the American Geophysical Meeting in San Francisco on Friday, Dec. 9.
The study, focusing on Quebec, is one of the first to present a detailed view of how warmer temperatures are influencing plant distribution and density in northern areas of North America.
"Unlike the decline of sea ice, which is a dramatic effect that we're seeing as a result of global warming, the changes in vegetation have been subtle," Masek says.
Computer models predict the northward expansion of vegetation due to warmer temperatures. "They predict a dramatic change over the next 100 years, and people have been wondering why we weren't seeing these changes already, Masek says.
The difference between the computer predictions and real-life vegetation may have to do with all the other factors that come into play with plants, like the availability of water and sunlight; the type of terrain; competition from other plants for soil, resources and space; and plant predators like caribou.
"The warm temperatures are only part of the equation," says Doug Morton, the Principal Investigator of the study and a researcher at NASA Goddard.
Scientists track vegetation with satellites by measuring the 'greenness' of a study area. Morton says previous studies used yearly compilations, making it difficult to determine if the increase in 'greenness' was due to expansion of vegetation cover or if what scientists were seeing was instead just the effect of a longer growing season.
For this study, the scientists focused only on 'greenness' measurements during the peak summer growing seasons from 1986 to 2010.
By using Landsat's higher, 30-meter (~98 foot) resolution and viewing the same area at the same time for 23 years, Masek and his colleagues were able to track the areas as they continued to show more 'greenness' over the years. "It makes sense," Masek says. "This is how shrub encroaching occurs. They increase in size, they increase in density, and then they move northward."
In contrast to the expansion of shrubs, the scientists found little evidence for 'greenness' trends in forested areas, suggesting that forest response to recent warming may be occurring more slowly. Masek adds that it shows how getting the big picture of warming's effect on forests will rely on continued observations from new U.S. missions that extend and enhance these data records.
The Landsat Program is a series of Earth-observing satellite missions jointly managed by NASA and the U.S. Geological Survey since 1972. They continue to improve and expand this unparalleled record of Earth's changing landscapes for the benefit of all.
For more information on Landsat, visit:http://www.nasa.gov/landsat Aries Keck
Aries Keck | EurekAlert!
Innovative genetic tests for children with developmental disorders and epilepsy
11.07.2018 | Christian-Albrechts-Universität zu Kiel
Oxygen loss in the coastal Baltic Sea is “unprecedentedly severe”
05.07.2018 | European Geosciences Union
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
16.07.2018 | Physics and Astronomy
16.07.2018 | Life Sciences
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domingo, 23 de octubre de 2011
Astronomy - Mystery of Arp 82 Galaxies
This spectacular interacting pair of galaxies, together called Arp 82, is a scientific oddball. The color in the "tilted S" pair indicate that the observed stars are young to intermediate in age, around 2 million to 2 billion years old, much less the age of the universe (13.7 billion years). Astronomers hotly debate why Arp 82 didn't form many stars earlier, like most galaxies of its mass.
Source: The Daily Galaxy
Publicado por Karla Segura Chavarría en 12:56 | <urn:uuid:9d10a664-f05d-4724-9229-7cab1e99bf8c> | 2.984375 | 132 | Personal Blog | Science & Tech. | 47.694315 | 95,556,903 |
Measurement and Modeling of Snow Energy Balance and Sublimation From Snow
Proceedings, International Snow Science Workshop
Snow melt runoff is an important factor in runoff generation for most Utah rivers and a large contributer to Utah's water supply and periodically flooding. The melting of snow is driven by fluxes of energy into the snow during warm periods. These consist of radiant energy from the sun and atmosphere, sensible and latent heat transfers due to turbulent energy exchanges at the snow surface and a relatively small ground flux from below. The turbulent energy exchanges are also responsible for sublimation from the snow surface, particularly in arid environments, and result in a loss of snow water equivalent available for melt. The cooling of the snowpack resulting from sublimation also delays the fOlmation of melt runoff. This paper describes measurements and mathematical modeling done to quantify the sublimation from snow. Measurements were made at the Utah State University drainage and evapotranspiration research farm. I attempted to measure sublimation directly using weighing lysimeters. Energy balance components were measured, by measuring incoming and reflected radiation, wind, temperature and humidity gradients. An energy balance snowmelt model was tested against these measurements. The model uses a lumped representation of the snowpack with two state variables, namely, water equivalent and energy content relative to a reference state of water in the solid phase at O°c. This energy content is used to detennine snowpack average temperature or liquid fraction. The model is driven by inputs of air temperature, precipitation, wind speed, humidity and solar radiation. The model uses physically based calculations of radiative, sensible, latent and advective heat exchanges. An equilibrium parameterization of snow surface temperature accounts for differences between snow surface temperature and average snowpack temperature without having to introduce additional state variables. This is achieved by incorporating the snow surface thennal conductance, which with respect to heat flux is equivalent to stomatal and aerodynamic conductances used to calculate evapotranspiration from vegetation. Melt outflow is a function of the liquid fraction, using Darcy's law. This allows the model to account for continued melt outflow even when the energy balance is negative. The purpose of the measurements presented here was to test the sublimation and turbulent exchange parameterizations in the model. However the weighing lysimeters used to measure sublimation suffered from temperature sensitive oscillations that mask short tenn sublimation measurements. I have therefore used the measured data to test the models capability to represent the overall seasonal accumulation and ablation of snow.
Tarboton, David G., "Measurement and Modeling of Snow Energy Balance and Sublimation From Snow" (1994). Civil and Environmental Engineering Faculty Publications. Paper 2589. | <urn:uuid:281929c5-a2ff-4844-a80d-3fbf8c05021b> | 2.765625 | 562 | Academic Writing | Science & Tech. | 9.0198 | 95,556,915 |
If you're searching for Whale Facts For Kids to help with your children's homework, to use as a website resource for your classroom, or to use in your lesson plan for your students, the information below can help.
Known to be the king and queens of the sea, whales have certain qualities that make them truly unique creatures. Understanding them is a task that one must undertake in order to realize their significance in the world’s ecosystem.
Anatomy of a Whale
Whales are mammals like humans and as a result, they are warm-blooded and they feed their young with milk from their mammary glands. For survival in the oceans, whales inhale air through their blowhole and release excess water. This inhale and expulsion of water forms a spout that can be used to determine the species of whale. Whales have thick bodies that are insulated by a layer of fat known as the blubber. Like other mammalsand vertebrates, they have a spinal column and a heart consisting of four chambers. In terms of feeding behavior, whales are regarded to be predators with their main diet being plankton and are aided by echolocation that uses sound frequencies to detect their prey. Whales produce very few offspring; however, they have been known to have a very high survival rate.
Although many species of whales exist, whales have been classified into two main sub-orders: Baleen and Toothed. The important difference between the two whale sub-orders is that the Baleen, known as the Mysticeti, does not have teeth unlike the Toothed, known as the Odontoceti. Some examples of common whales under the Baleen whale sub-order are: the Humpback Whale, the Blue Whale, and the Northern Pacific Right Whale. A total of fourteen species and four families have been fully known for the Baleen whales. For the Toothed whale sub-order, some commonly known whales are: the Sperm Whale, the Beluga, and the Northern Bottlenose Whale. The Toothed whales have a more diversified amount of species with porpoises and dolphins part of this sub-order.
Whales are of great value to humans because they contain things that are useful in the livelihood of people. Whales have a huge supply of meat and oil. The need of whale meat for food is present in the Inuits of Alaska who have no other source because of the harsh environment. Including that, certain species, such as the Sperm whale, have ambergris, a perfume ingredient. The baleen of Baleen Whales have been also been sold commercially. These things cannot be extracted unless the whale has been killed; this is known as whaling. Whaling has been known to diversely alter the whale population because the birth rate is significantly low; eliminating one whale really puts the population at risk. Why Japan Supports Whaling? Japanese and Icelandic authorities have sought to whaling in order to stop them from depleting other important food sources such as capelin and herring. As a result of such activity, almost 2 million whales have been killed by the 20th century. In response to this activity, the International Whaling Commission has put a ban on whaling; however other nations continue for research and food-provision.
Whales have been decreasing because of the whaling activity and the human activity that has hindered their communication. Whales communicate by sending off signals to each other. These signals are sent off in frequencies that are picked up even through long distances and to the human ears, they sound somewhat similar to a moan or a screech. Other whale sounds may be simple clicks, as shown in Toothed Whales. When whales intend to mate, these signals resemble songs which are sent off by male whales which are picked up by the females. Throughout time, these signals had been fluid and the whale population progressed. The migratory routes of whales usually lie near the shoreline but recently, the shorelines have been filled with much interference of human activity that the whales could not communicate efficiently. They opt to prevent whaling and overall protect the species at hand. The American Cetacean Society is an organization that makes people aware of the dangers faced by whales cause by whaling and other whale-detrimental activities. These missions have shown to help put the whale population back on its track, and hopefully letting the female whales finally hear the prolonged male songs. The Advocacy on Saving the Right Whale believes endangered Right Whale species has been called for to be saved.
Whales are very beautiful creatures especially in the comfort of their natural habitats. People have taken the time to devote to whale watching, an activity that involves the observing whales as they frolic in their own environment. Other than entertainment purposes, whale watching has been done for educational purposes in order to learn more about the whales, and scientific purposes that entail the study of whale behavior. Ideal locations for whale watching include: the Atlantic, the Pacific, Africa, Australia, the North Indian, and Costa Rica. Whales can be observed off the coast like in Atlantic regions, blue whales may be seen off the Bay of Biscay. In Northern Norway, orcas have been seen. In the Philippines alone, thirty different whale species may be observed around the Central Visayas. Southern Africa, off the town of Hermanus, is regarded as one of the world’s whale watching hot spots. Whales can also be seen in Sydney Harbor migrating south. Whale watching has been known to produce $1 billion in worldwide revenue and Iceland has been known to have the most booming whale watching industry.
Although whales are underwater creatures, whales usually come up to the surface in order to understand the environment overhead. Because they are conscious of their surroundings, whales have center behaviors that give them an idea of the setting around them. Breaching is when the whale propels itself off the water with a twisting motion. This is done either for entertainment, or in the loosening of skin parasites. This movement may have a symbolic means of communicating with other whales. Lunging is done by moving forward on the surface with the head above water. This is done as a form of closing in on the females in competition with other males. Sometimes the whole body of the whale may be above water, resembling the leap of a porpoise. This is known as porpoising and is done usually for play. Spyhopping is when a whale will vertically rise to a point with the eyes above the water as they begin to observe the surroundings.
Below you will find additional resources and facts for kids related to the article "Whale Facts For Kids". | <urn:uuid:28b6a3be-6235-480a-92f2-9c071854222a> | 3.875 | 1,356 | Knowledge Article | Science & Tech. | 42.12698 | 95,556,937 |
By: Yudai Koyama And Moonsu Kim. Jeopardy! Volcanoes. 100-Vocabulary. Define volcano. ANSWER 100-Vocabulary. A vent from which the material from a magma chamber escapes. 2 00-Vocabulary. Define viscosity. Viscosity!. ANSWER 200-Vocabulary. A liquids resistance to flow.
A vent from which the material from a magma chamber escapes.
A liquids resistance to flow
Define pyroclastic material.
The combination of all materials ejected during a volcanic eruption.
Alarge volcanic crater, typically one formed by a major eruption leading to the collapse of the mouth of the volcano.
Rock material ejected from the vent during a volcanic eruption.
Where can a volcano form?
Along plate boundaries. Anywhere magma can form.
Volcanoes erupt because mantle rocks melts and becomes magma. What are the three conditions mantle rocks can melt?
If temperature rises, if pressure lowers, and if water is added.
Name and explain the three stages of a volcano.
Explain mafic magma and felsic magma.
What are three things magma composition determine?
Fill in blank.
Large, explosive eruptions contain more energy than an _______________.
What is a pyroclastic flow?
Why is effusive much less deadly?
Slower, so people can evacuate.
What are the three type of lava flow?
Explain the three types of lava flows.
True or False
A super volcano is a very rare event in Earth's history?
What is the shape of the volcano directly related to?
Name the three shapes of a volcano.
Explain the shape of the three types of volcanoes.
Name a place that is considered as a super volcano.
Is predicting volcanic eruptions harder to predict or is earthquakes harder to predict?
Earthquakes are harder to predict.
What is interplate volcanism?
When a volcano occurs in the middle of plates.
Define mantle plume
Mantle plume: An upwelling of upwelling of unusually hot mantle plume
Hotspots: a magma chamber developed above the mantle plume
How do scientists predict volcanic eruptions? Name three factors that can be taken into account. | <urn:uuid:b6f3b800-c830-4b3c-b21c-9b1a6b304f89> | 3.796875 | 492 | Content Listing | Science & Tech. | 44.100752 | 95,556,952 |
Researchers at the J Craig Venter Institute recently unveiled their first self-replicating synthetic bacteria (M. mycoides JCVI-syn1.0) whose DNA was ‘programmed’ base pair by base pair. To verify that they had synthesized a new organism and not assembled the DNA from another natural bacteria, scientists encoded a series of ‘watermarks’ into the genes of M. mycoides JCVI-syn1.0. There are four of these hidden messages: an explanation of the coding system used, a URL address for those who crack the code to go visit, a list of 46 authors and contributors, and a series of famous quotes. The presence of these watermarks verifies that M. mycoides JCVI-syn1.0 truly is synthetic and demonstrates the precision and power of JCVI’s new techniques in synthetic biology.
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It turns out that the secret message in the watermark is partly in HTML. It’s amazing to think that they actually put HTML into the DNA of a living organism. They claim the code also supports Perl and Java, but that’s not present in this organism. | <urn:uuid:49c235ed-0d6b-4729-b620-0c8af216a2c8> | 2.671875 | 272 | News (Org.) | Science & Tech. | 56.470234 | 95,556,964 |
Airborne pollution from South Asia is helping to brew monster storms in the Arabian Sea that have claimed thousands of lives and cost billions of dollars, scientists said on Wednesday.
In a paper published in the British journal Nature, researchers pointed the finger at a haze known as the Asian brown cloud, which hangs over parts of the northern Indian Ocean, India and Pakistan.
Several kilometres (two miles) thick, the cloud comprises brownish particles of carbon soot and sulphates spewed by factories, diesel exhaust and poorly-burnt biomass. Previous research has implicated it in disrupting monsoon patterns and in glacier loss in the Himalayas.
Environmental scientists led by Amato Evan of the University of Virginia looked at patterns in cyclones in the Arabian Sea from 1979 to 2010.
They found the region historically only averaged two or three cyclones a year and these typically were weak — even though the sea was clearly hot enough to fuel very powerful storms.
The reason for the weakness and infrequency, they discovered, lies in a phenomenon called vertical wind shear which occurs in July and August during the hot months of the monsoon season.
Vertical wind shear occurs when strong winds flow in the upper and lower atmosphere in opposite directions. In the lower levels, it blows from the southwest, and in the upper atmosphere, from the east.
The shear rips the top off a would-be cyclone, preventing it from developing the circular winds that are its muscular hallmark.
As a result, the few cyclones that occurred in the Arabian Sea typically happened before or after the monsoon season — usually one in May/June and a couple more in August to December — when the wind shear was far less.
But in the last dozen or so years, the pattern has changed, with the emergence of storms in the weeks immediately before the monsoon season.
They include a cyclone that killed nearly 3,000 people in Gujarat, India, in June 1998.
In June 2007, cyclone Gonu, a category five storm, killed 49 people in Oman and Iran, causing more than four billion dollars in damage. It was the first documented storm ever to enter the Gulf of Oman.
And in June 2010, 26 people were killed in Pakistan and Oman by a category-four cyclone, Phet, inflicting losses of nearly two billion dollars.
The team says “brown cloud” particulates have grown six-fold in volume since the 1930s and the pollution is now a disruptive climatic phenomenon in its own right.
Its dark colour absorbs sunlight, making it a source of heat and causing a cooling of the ocean below — which in turn affects wind circulation and the transport of warmth from the sea to the atmosphere.
Drawn from direct observations and computer models, the conclusion is that the cloud weakens wind shear, essentially lifting the brake on cyclone development.
“This study is a striking example of how human reactions, on a large enough scale — in this case, massive regional air pollution caused by inefficient fuel combustion — can result in unintended consequences,” said Anjuli Bamzai of the US National Science Foundation.
“These consequences include highly destructive summer cyclones that were rare or non-existent in this monsoon region 30 or so years ago.”
Arabian Sea cyclones could be particularly hazardous because they are born in a small area of ocean compared to the tropical western Atlantic and the western Pacific, the study warned.
“Given the relatively small size of the Arabian basin, more than half of all cyclones that form here make landfall, and even weak landfalling Arabian Sea cyclones can cause considerable destruction and loss of life.” | <urn:uuid:e12fcc9d-d5e6-4893-8617-6d6de78d3549> | 3.609375 | 756 | News Article | Science & Tech. | 37.172601 | 95,556,972 |
In the paper, the fog formation factors were analyzed at the Monggumpo area of the central coast of Korea. Through the analysis of meteorological factors such as temperature, humidity in atmospheric lower layer, surface wind, and sea water temperature, we revealed the cause of fog formation at Monggumpo water area. For the analysis, fog observations from 2012 to 2014 (April to August) and RJTD semi-regular analysis data were used.
Comments: 12 Pages.
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One small “hot spot” in the U.S. Southwest is responsible for producing the largest concentration of the greenhouse gas methane seen over the United States – more than triple the standard ground-based estimate — according to a new study of satellite data.
Methane is very efficient at trapping heat in the atmosphere and, like carbon dioxide, it contributes to global warming. The hot spot, near the Four Corners intersection of Arizona, Colorado, New Mexico and Utah, covers only about 6,500 square kilometers (2,500 square miles), or half the size of Connecticut.
This map shows anomalous U.S. methane emissions (or how much the emissions differ from average background concentrations) for 2003 to 2009, as measured by the European Space Agency’s SCIAMACHY instrument. Purple and dark blue areas are below average. Pale blue and green areas are close to normal or slightly elevated. Yellows and red indicate higher-than-normal anomalies, with more intense colors showing higher concentrations. The Four Corners area – the area where Arizona, Colorado, New Mexico and Utah meet — is the only red spot on the map.
Credit:NASA/JPL-Caltech/University of Michigan
In each of the seven years studied from 2003-2009, the area released about 0.59 million metric tons (0.65 million U.S. tons) of methane into the atmosphere. This is almost 3.5 times the estimate for the same area in the European Union’s widely used Emissions Database for Global Atmospheric Research.
In the study published online today in Geophysical Research Letters, a journal of the American Geophysical Union, researchers used observations made by the European Space Agency’s Scanning Imaging Absorption Spectrometer for Atmospheric Chartography (SCIAMACHY) instrument.
SCIAMACHY measured greenhouse gases from 2002 to 2012. The atmospheric hot spot persisted throughout the study period.
A ground station in the Total Carbon Column Observing Network, operated by the Department of Energy’s Los Alamos National Laboratory, provided independent validation of the measurement.
To calculate the emissions rate that would be required to produce the observed concentration of methane in the air, the authors performed high-resolution regional simulations using a chemical transport model, which simulates how weather moves and changes airborne chemical compounds.
Research scientist Christian Frankenberg of NASA’s Jet Propulsion Laboratory (JPL) in Pasadena, California, first noticed the Four Corners signal years ago in SCIAMACHY data.
“We didn’t focus on it because we weren’t sure if it was a true signal or an instrument error,” Frankenberg said.
The study’s lead author, Eric Kort of the University of Michigan, Ann Arbor, noted the study period predates the widespread use of hydraulic fracturing, known as fracking, near the hot spot. This indicates the methane emissions should not be attributed to fracking but instead to leaks in natural gas production and processing equipment in New Mexico’s San Juan Basin, which is the most active coalbed methane production area in the country.
Natural gas is 95-98 percent methane. Methane is colorless and odorless, making leaks hard to detect without scientific instruments.
“The results are indicative that emissions from established fossil fuel harvesting techniques are greater than inventoried,” Kort said. “There’s been so much attention on high-volume hydraulic fracturing, but we need to consider the industry as a whole.”
Coalbed methane is gas that lines pores and cracks within coal. In underground coal mines, it is a deadly hazard that causes fatal explosions almost every year as it seeps out of the rock. After the U.S. energy crisis of the 1970s, techniques were invented to extract the methane from the coal and use it for fuel. By 2012, coalbed methane supplied about 8 percent of all natural gas in the United States.
Frankenberg noted that the study demonstrates the unique role space-based measurements can play in monitoring greenhouse gases.
“Satellite data cannot be as accurate as ground-based estimates, but from space, there are no hiding places,” Frankenberg said.
In March 2014 the Obama Administration announced a strategy to reduce methane emissions under its Climate Action Plan. The strategy includes improving the measurement and monitoring of methane emissions and assessing current methane emissions data.
The American Geophysical Union is dedicated to advancing the Earth and space sciences for the benefit of humanity through its scholarly publications, conferences, and outreach programs. AGU is a not-for-profit, professional, scientific organization representing more than 62,000 members in 144 countries. Join our conversation on Facebook, Twitter, YouTube, and other social media channels.
NASA monitors Earth’s vital signs from land, air and space with a fleet of satellites and ambitious airborne and ground-based observation campaigns. NASA develops new ways to observe and study Earth’s interconnected natural systems with long-term data records and computer analysis tools to better see how our planet is changing. The agency shares this unique knowledge with the global community and works with institutions in the United States and around the world that contribute to understanding and protecting our home planet.
For more information about NASA’s Earth science activities in 2014, visit: http://www.nasa.gov/earthrightnow
Notes for Journalists
Journalists and public information officers (PIOs) of educational and scientific institutions who have registered with AGU can download a PDF copy of this article by clicking on this link: http://onlinelibrary.wiley.com/doi/10.1002/2014GL061503/abstract
Or, you may order a copy of the final paper by emailing your request to Nanci Bompey at email@example.com. Please provide your name, the name of your publication, and your phone number.
Neither the paper nor this press release is under embargo.
“Four Corners: the largest US methane anomaly viewed from space”
Eric A. Kort: Atmospheric, Oceanic and Space Sciences, University of Michigan, Ann Arbor, MI, USA;
Christian Frankenberg: Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, USA;
Keeley R. Costigan: Earth and Environmental Sciences, Los Alamos National Lab, Los Alamos, NM, USA;
Rodica Lindenmaier: Earth and Environmental Sciences, Los Alamos National Lab, Los Alamos, NM, USA; and Atmospheric Chemistry and Global Change Division, now at Pacific Northwest National Laboratory, Richland, WA, USA;
Manvendra K. Dubey: Earth and Environmental Sciences, Los Alamos National Lab, Los Alamos, NM, USA;
Debra Wunch: California Institute of Technology, Pasadena, CA, USA.
Contact information for the authors:
Eric Kort: +1 (734) 763-8414,firstname.lastname@example.org
Christian Frankenberg: +1 (818) 354-1087, Christian.Frankenberg@jpl.nasa.gov
+1 (202) 777-7524
NASA Headquarters Contact:
+1 (202) 358-0918
NASA Jet Propulsion Laboratory Contact:
+1 (818) 354-0474
University of Michigan Contact:
Nicole Casal Moore
+1 (734) 647-7087
Nanci Bompey | American Geophysical Union
New research calculates capacity of North American forests to sequester carbon
16.07.2018 | University of California - Santa Cruz
Scientists discover Earth's youngest banded iron formation in western China
12.07.2018 | University of Alberta
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
17.07.2018 | Information Technology
17.07.2018 | Materials Sciences
17.07.2018 | Power and Electrical Engineering | <urn:uuid:8b43eabf-8f97-4ea9-9a47-4145538aaed6> | 3.59375 | 2,193 | Content Listing | Science & Tech. | 36.823799 | 95,556,994 |
Science fiction is fast approaching science fact as researchers are progressing rapidly toward "bottling" antimatter.
In a paper published online today by the journal Nature Physics, the ALPHA experiment at CERN, including key Canadian contributors, reports that it has succeeded in storing antimatter atoms for over 16 minutes. While carrying around bottled antimatter like in the movie Angels and Demons remains fundamentally far-fetched, storing antimatter for long periods of time opens up new vistas for scientists struggling to understand this elusive substance.
ALPHA managed to store twice the antihydrogen (the antimatter partner to normal hydrogen) 5,000 times longer than the previous best, setting the stage, for example, to test whether antihydrogen and normal hydrogen fall the same way due to gravity.
Lead author Makoto Fujiwara, TRIUMF research scientist, University of Calgary adjunct professor, and spokesperson of the Canadian part of the ALPHA team said, "We know we have confined antihydrogen atoms for at least for 1,000 seconds. That's almost as long as one period in hockey! This is potentially a game changer in antimatter research."
Antimatter remains one of the biggest mysteries of science. At the Big Bang, matter and antimatter should have been produced equally, but since they destroy each other upon contact, eventually nothing should have remained but pure energy (light). However, all observations suggest that only the antimatter has vanished. To figure out what happened to "the lost half of the universe," scientists are eager to determine if, as predicted, the laws of physics are the same for both matter and antimatter. ALPHA uses an analogue of a very well-known system in physics, the hydrogen atom (one electron orbiting one proton), and testing whether its antimatter twin, antihydrogen (an antielectron orbiting an antiproton), behaves the same. But to study something one must hold onto it long enough.
Fujiwara asks, "Does antimatter shine in the same colour as matter? Does it experience the gravity in the same way as matter?" These are still very difficult experiments, and they will take long and hard work, but this new result is a very important step. Now experiments will be about 10,000 times less difficult than before!" Explained ALPHA spokesperson Jeffrey Hangst of Aarhus University, "This would provide the first-ever look inside the structure of antihydrogen - element 1 on the anti-periodic table."
Antihydrogen atoms were first made in large quantities at CERN eight years ago, but can't be stored conventionally since antiatoms touching the ordinary-matter walls of a bottle would instantly annihilate. The ALPHA collaboration succeeded by developing a sophisticated "magnetic bottle" using a state-of-the-art superconducting magnet to suspend the antiatoms away from the walls, last year demonstrating definitive proof of antihydrogen atom capture for about a tenth of a second, likely the first contained antiatoms in the history of the universe.
Canadian scientists have been playing leading roles in the antihydrogen detection and data analysis aspects of the project. The next step for ALPHA is to start performing measurements on bottled antihydrogen, and this is due to get underway later this year. The first step is to illuminate the trapped anti-atoms with microwaves to determine if they absorb exactly the same frequencies (or energies) as their matter twins.
"I've always liked hydrogen atoms," said Walter Hardy of the University of British Columbia a leading expert in atomic hydrogen studies. "It's ironic that we are now trying to measure the same properties of antihydrogen that I measured many years ago on regular hydrogen. It is a crucial comparison, though, and will tell us if we truly understand the relationship between matter and antimatter. "
Support for ALPHA-Canada and its research came from NSERC (National Science and Engineering Research Council, TRIUMF, AIF (Alberta Ingenuity Fund), the Killam Trust, and FQRNT (Le Fonds québécois de la recherche sur la nature et les technologies).
About TRIUMF: TRIUMF is Canada's national laboratory for particle and nuclear physics. Located on the south campus of the University of British Columbia, TRIUMF is owned and operated as a joint venture by a consortium of the following Canadian universities, via a contribution through the National Research Council Canada and building capital funds from the Government of British Columbia: University of Alberta, University of British Columbia, University of Calgary, Carleton University, University of Guelph, University of Manitoba, McMaster University, Université de Montréal, University of Northern British Columbia, Queen's University, University of Regina, Saint Mary's University, Simon Fraser University, University of Toronto, University of Victoria, University of Winnipeg, York University. See http://www.triumf.ca.
About ALPHA-Canada: ALPHA is a collaboration of about 40 physicists from 15 institutions from Canada, Brazil, Denmark, Israel, Japan, Sweden, UK, and the USA. ALPHA-Canada currently consists of 8 senior scientists, 5 graduate students, and several professional staff from 5 Canadian institutions. ALPHA-Canada constitute about one third of the entire ALPHA collaboration. 14 out of 40 ALPHA co-authors in the reported work are with ALPHA-Canada: Andrea Gutierrez, Sarah Seif El Nasr, Walter Hardy (Univ. of British Columbia), Tim Friesen, Richard Hydomako, Robert Thompson (Univ. of Calgary), Mohammad Ashkezari, Michael Hayden (Simon Fraser Univ.), Scott Menary (York Univ.), Makoto Fujiwara, David Gill, Leonid Kurchaninov, Konstantin Olchanski, Art Olin, James Storey (TRIUMF). See http://alpha.web.cern.ch/alpha & http://angelsanddemons.cern.ch.
Makoto Fujiwara | EurekAlert!
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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Researchers from three universities say massive features such as Yosemite's El Capitan form as part of a 'reverse energy cascade' that traps rising magma in the crust
Volcanic eruptions such as Mount St. Helens' in 1980 show the explosiveness of magma moving through the Earth's crust. Now geologists are excited about what uplifted granite bodies such as Yosemite's El Capitan say about magma that freezes before it can erupt on the surface.
These granite structures, called magmatic intrusions, form incrementally over time by small pulses of magma that cool and crystalize 5 to 20 kilometers -- 3 to 12 miles -- underground. Many are uplifted and exposed by erosion. They also contain the history of magma injections that occurred tens to hundreds of millions of years ago, says Leif Karlstrom of the University of Oregon.
In a paper placed online July 10 by the journal Nature Geoscience, a three-member research team led by Karlstrom unveiled a new framework for understanding what the pattern of volcanoes seen at the surface implies about the structure of subsurface magma plumbing systems. Some 50 to 90 percent of magma, Karlstrom said, doesn't get through the crust.
"Granitic landscapes in the Yosemite Valley in California and in the North Cascades are iconic, huge cliffs with exposed rock," he said. "If you look closer, the structure of that landscape shows all kinds of intrusive bodies that record different pulses of magma coming into the crust. Our findings hopefully allow you to stare up at El Capitan and make sense of it in some new way."
In the National Science Foundation-funded research, Karlstrom, Scott R. Paterson of the University of Southern California and A. Mark Jellinek of the University of British Columbia examined more than a decade of measurements of size distributions of igneous rock intrusions in the North American Cordillera.
Magma rising in active volcanic regions in places such as the Cascades, Hawaii and Iceland, Karlstrom said, often occurs as narrow, sheet-like intrusions commonly called dikes and sills. This occurs as a cracking process in brittle crustal rocks. Over long timescales, however, the process changes.
These changes are part of a transition into a "reverse energy cascade," in which rising magma injections become trapped and lose energy, the researchers say.
Magma mixes and merges with surrounding rocks as it cools and crystalizes. Heat lost from repeated injections of magma continues to heat crustal rocks, building and the expanding granitic intrusive complexes formed by frozen magma in a viscous, rather than brittle, manner. The resulting structures are seen today where the formations are exposed.
"That act of dumping heat into the crust over time changes the nature of the mechanical response to injections of magma," Karlstrom said. "The earth's crust is a filter for rising melts. You have magma that is generated deep in the earth, and somehow it gets to the surface carrying heat and volatiles, such as carbon dioxide. How that happens is through the crustal magma transport system."
Studying the processes behind magma injections over long timescales, he said, helps build better understanding of volcanoes, their impacts on global climate and where large volcanoes are likely to occur.
"This paper hits on one of the primary current research problems in volcanology," Karlstrom said. "We are able to make a strong statement about the connection of deep intrusive magmatism to the surface expression of volcanism. We think that what we found provides a framework for understanding other kinds of problems related to magmatism on Earth and other planets."
Source: Leif Karlstrom, assistant professor, Department of Earth Sciences, email@example.com
Note: The UO is equipped with an on-campus television studio with a point-of-origin Vyvx connection, which provides broadcast-quality video to networks worldwide via fiber optic network. There also is video access to satellite uplink and audio access to an ISDN codec for broadcast-quality radio interviews.
About Karlstrom: http://pages.
Department of Earth Sciences: https:/
Jim Barlow | EurekAlert!
New research calculates capacity of North American forests to sequester carbon
16.07.2018 | University of California - Santa Cruz
Scientists discover Earth's youngest banded iron formation in western China
12.07.2018 | University of Alberta
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
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18.07.2018 | Health and Medicine | <urn:uuid:dc6a0117-22af-4196-9461-b87b2ac34c3c> | 3.765625 | 1,501 | Content Listing | Science & Tech. | 39.642854 | 95,557,013 |
"Intermediate-mass black holes contain between 100 and 10,000 times the sun's mass," explained Tod Strohmayer, an astrophysicist at Goddard. "We observe the heavyweight black holes in the centers of galaxies and the lightweight ones orbiting stars in our own galaxy. But finding the 'tweeners' remains a challenge."
Several nearby galaxies contain brilliant objects known as ultraluminous X-ray sources (ULXs). They appear to emit more energy than any known process powered by stars but less energy than the centers of active galaxies, which are known to contain million-solar-mass black holes.
"ULXs are good candidates for intermediate-mass black holes, and the one in galaxy NGC 5408 is especially interesting," said Richard Mushotzky, an astrophysicist at the University of Maryland, College Park. The galaxy lies 15.8 million light-years away in the constellation Centaurus.
This archival image taken by the Hubble Space Telescope shows the location of NGC 5408's unusually luminous X-ray source (circled). The irregular-type galaxy lies 15.8 million light-years away in the constellation Centaurus. Credit: NASA/ESA/C. Lang, P. Kaaret, A. Mercer (Univ. of Iowa), and S. Corbel (Univ. of Paris) Using the European Space Agency's orbiting XMM-Newton observatory, Strohmayer and Mushotzky studied the source -- known as NGC 5408 X-1 -- in 2006 and 2008.
XMM-Newton detected what the astronomers call "quasi-periodic oscillations," a nearly regular "flickering" caused by the pile-up of hot gas deep within the accretion disk that forms around a massive object. The rate of this flickering was about 100 times slower than that seen from stellar-mass black holes. Yet, in X-rays, NGC 5408 X-1 outshines these systems by about the same factor.
Based on the timing of the oscillations and other characteristics of the emission, Strohmayer and Mushotzky conclude that NGC 5408 X-1 contains between 1,000 and 9,000 solar masses. This study appears in the October 1 issue of The Astrophysical Journal.
"For this mass range, a black hole's event horizon -- the part beyond which we cannot see -- is between 3,800 and 34,000 miles across, or less than half of Earth's diameter to about four times its size," said Strohmayer.
If NGC 5408 X-1 is indeed actively gobbling gas to fuel its prodigious X-ray emission, the material likely flows to the black hole from an orbiting star. This is typical for stellar-mass black holes in our galaxy.
Strohmayer next enlisted the help of NASA's Swift satellite to search for subtle variations of X-rays that would signal the orbit of NGC 5408 X-1's donor star. "Swift uniquely provides both the X-ray imaging sensitivity and the scheduling flexibility to enable a search like this," he added. Beginning in April 2008, Swift began turning its X-Ray Telescope toward NGC 5408 X-1 a couple of times a week as part of an on-going campaign.
Swift detects a slight rise and fall of X-rays every 115.5 days. "If this is indeed the orbital period of a stellar companion," Strohmayer said, "then it's likely a giant or supergiant star between three and five times the sun's mass." This study has been accepted for publication in a future issue of The Astrophysical Journal.
The Swift observations cover only about four orbital cycles, so continued observation is needed to confirm the orbital nature of the X-ray modulation.
"Astronomers have been studying NGC 5408 X-1 for a long time because it is one of the best candidates for an intermediate-mass black hole," adds Philip Kaaret at the University of Iowa, who has studied the object at radio wavelengths but is unaffiliated with either study. "These new results probe what is happening close to the black hole and add strong evidence that it is unusually massive."
Francis Reddy | 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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Physics Question #110
Jonjon, a 16 year old male from the Internet asks on January 2, 2000,
How does a pressure cooker work?
viewed 17938 times
answered on January 2, 2000
A pressure cooker is a pot of boiling water which has been sealed shut. Because the water vapour cannot escape to the atmosphere at the boiling point, 100 degrees C, the temperature and pressure increase above that temperature. This means that food cooks faster in a pressure cooker. Pressure cookers all have pressure release valves so that the pressure does not build up too much and blow up the whole pot. To understand fully the relationship between Temperature, Pressure and Volume, read about the gas law (PV=nrt) in an introductory chemistry or physics book.
answered on October 20, 2005
You can determine the temperature of the water in a pressure cooker by looking at a steam table in an introductory thermodynamics textbook. A good quality pressure cooker that you would use at home operates at a gauge pressure of 103 kilopascals (kPa) [15 pounds per square inch (psi)]. To see a sample construction of a modern new generation pressure cooker have a look at the site Fastcooking.ca and click on “How It Works”. The cooking times of foods are decreased dramatically when using a pressure cooker. The steam pressure breaks down the fibres of the food a lot faster than just boiling the food would do. Because the food is cooked so quickly, the energy needed to cook the food is 50-75% less than other cooking methods.
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Viewed: [[ro.stat.viewed]] Cited: [[ro.stat.cited]] Accessed: [[ro.stat.accessed]]
ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Adc&rfr_id=info%3Asid%2FANDS&rft_id=https://df.arcs.org.au/ARCS/projects/PICCLOUD/data/EARTH%20SCIENCE/BIOLOGICAL%20CLASSIFICATION/PLANTS/dpAvyFxCMLrsJoUNUbWO/GmlVNcJrWD1275676237036.zip&rft.title=Impact of changes in UV and visible radiation on the reflective properties of plant photosynthetic surfaces&rft.publisher=Polar Information Commons&rft.description=We investigated how surface reflectance properties and pigment concentrations of Antarctic moss varied over species, sites, icrotopography, and with water content. We found that species had significantly different surface reflectance properties, particularly in the region of the red edge (approximately 700 nm), but this did not correlate strongly with pigment concentrations. Surface reflectance of moss also varied in the visible region and in the characteristics of the red edge over different sites. Reflectance parameters, such as the Photochemical Reflectance Index (PRI) and Cold Hard Band (CBH) were useful discriminators of site, microtopographic position and water content. The PRI was correlated both with the concentrations of active xanthophyll-cycle pigments and the photosynthetic light use efficiency, Fv\/Fm, measured using chlorophyll fluorescence. Water content of moss strongly influenced the amplitude and position of the red-edge as well as the PRI, and may be responsible for observed differences in reflectance properties for different species and sites. All moss showed sustained high levels of photoprotective xanthophyll pigments, especially at exposed sites, indicating moss is experiencing continual high levels of photochemical stress. The fields in this dataset are: Sample Ridge\/Valley Site Species Pigments The site codes used in this dataset are: ROB = Robinson Ridge (Windmill Islands) RS = Red Shed (Casey Living Quarters - inside station limits) SC = Science Building (Casey - inside station limits) The species codes used in this dataset are: B = Bryum pseudotriquetrum C = Ceratodon purpureus G= Grimmia antarctici&rft.creator=Sharon Robinson&rft.date=2010&rft.coverage=-180.0,-66.0 -180.0,-85.0 179.0,-85.0 179.0,-66.0 -180.0,-66.0 -180.0,-66.0 &rft_subject=Earth Science - Biological Classification - Plants&rft_subject=Earth Science - Biosphere - Ecological Dynamics&rft_subject=Earth Science - Biosphere - Vegetation&rft_subject=Biota&rft.type=dataset&rft.language=English Access the data
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How To Get Started With Test Driven Development Today
Kyle Galbraith Apr 8 Updated on Apr 27, 2018
Test-driven development (TDD) is the act of writing tests before writing any code. Also known as red/green testing because you write the test, it fails, and then you write the code that makes it pass.
This process has a lot of different benefits such as simpler designs, more test coverage, and improved code quality. It provides a structure for developers to operate within that can often yield useful coding standards. If a team adopts TDD then all developers write tests for the code they write.
But if you are completely new to TDD, then getting started with it can be fuzzy. It turns out that it is quite simple to get started.
Dip Your Toes Into TDD
In the ideal world, all features have their expected behavior ahead of time. But in reality, product managers change their minds, use cases shift, and expected behaviors shift with them. This adds a twist to TDD that can be frustrating at first.
For TDD newbies, trying to write tests before a feature is even developed can be a mental blocker. You feel stuck or slowed down by TDD because the expected behaviors are not nailed down yet. Often times you have to iterate on your tests as requirements change. This is not a bad thing, but it can be a challenging place to start.
In fact, it is this twist that causes stakeholders to say "TDD is taking to long". The reality is that TDD is all about setting yourself up for faster development in the future. Every test written is a notch in the belt of better code quality and faster development.
If you are working with a legacy code base, a TDD experiment is just one bug away. Every piece of software has them, and they tend to have expected versus actual behaviors. These are great areas to start applying TDD concepts.
Follow these 7 steps to get familiar with test-driven development.
- The bug must be reproducible and have expected behavior.
- Now find where in the code the bug is at.
- Create a unit test that has the expected behavior.
- Run your new test and see that it fails.
- Update the code to produce the expected behavior.
- Run your new test again and see that it passes.
- Perform any refactoring on the code your test covers.
Just like that, you have applied the TDD concepts. Simple right? Almost too simple. There are some important details that I glossed over in regards to a couple of these steps.
The bug must be reproducible and have expected behavior
If there is an open question of whether is a bug than it isn't a great bug to start your TDD adventure on. Why? Because these type of bugs have unclear expected behaviors, so what is your test suppose to test?
Create a unit test that has the expected behavior
In legacy systems that have unit tests already, this might be trivial. If you are in a system that does not have any unit tests already than you are breaking new ground. With new ground comes refactoring code. Why? Because these codebases often need to be made testable. Adding dependency injection, making classes and functions single responsibility, and maybe using interfaces.
Perform any refactoring on the code your test covers
This is campsite policy, leave the code better than how you found it. If you think it is spotless, double check with someone on your team. The code is a living organism that evolves with every commit. It must be maintained, cleaned, and optimized where it can be. With good unit testing in place, you can do this maintenance and know if you broke something you shouldn't have.
What about features?
Once you are familiar with TDD concepts you should apply them to new features as well. The process is the same for the most part. Some folks write a few lines of the feature and then write the tests. Others write all the tests and then write the feature.
There is a spectrum of TDD folks that have very strong opinions on which of these correct. I am of the opinion that they are both great because there are tests either way.
What about the changing requirements? It's not a big deal. Why? Because if the requirement changes then you update your test, see it fail, and then update the code. By putting in the work to write tests before/in parallel with your feature than iterating on your feature is a breeze.
Test-driven development (TDD) is a very powerful tool in creating software. It enables a team to develop maintainable and high-quality code. But, it is not the only tool. Pair programming, bite-size stories, and fast iterative development are critical tools to have in place as well.
Learn AWS By Actually Using It
If you enjoyed this post and are hungry to start learning more about Amazon Web Services, I have created a new course on how to host, secure, and deliver static websites on AWS! It is a book and video course that cuts through the sea of information to accelerate your learning of AWS. Giving you a framework that enables you to learn complex things by actually using them. | <urn:uuid:243b728d-0b36-4f3e-ab4b-0254c0f336f2> | 2.953125 | 1,085 | Tutorial | Software Dev. | 60.145935 | 95,557,067 |
Many coastal habitats are found in and around estuaries, including salt marshes, sandy beaches, mud and sand flats, rocky shores, oyster reefs, mangrove forests, tidal pools and seagrass beds. Estuaries are sheltered bodies of water where rivers meet the sea, nutrient-rich freshwater mixes with saltwater, and sunlight penetrates the shallow depths. All of these conditions combine to create some of the most biologically-rich waters on the planet. Species able to adapt to the changing environment and sometimes harsh conditions thrive in estuaries.
Because they are biologically productive, estuaries attract migratory birds as places to feed and stop over during annual migrations. Estuaries also serve as nursery areas where fish and shellfish can grow and mature. Most important species of marine fish harvested as seafood or caught by recreational anglers rely on estuaries at some point in their life histories.
Over half of the U.S. population lives within 100 miles of a coast, including watersheds that empty into estuaries. Increased runoff of pollutants and sediments from urban and agricultural development impacts on water quality in estuaries. Excessive amounts of nitrogen and phosphorous can fuel blooms of algae that deplete waters of life-giving oxygen. Dams and flood control structures also can change the amounts and rates of freshwater flows. Regional cooperation among local governments, states and federal agencies such as the National Park Service is helping to address these challenges.
Move to What You Can Do?
Here are 10 tips from the NOAA that you can do to help protect estuaries. | <urn:uuid:a95f3d26-a45c-451f-8e8d-9ae28f24669f> | 4.15625 | 326 | Knowledge Article | Science & Tech. | 36.632743 | 95,557,072 |
Modern humans arrival in South Asia may have led to demise of indigenous populations
In a major new development in human evolutionary studies, researchers from the University of Cambridge argue that the dispersal of modern humans from Africa to South Asia may have occurred as recently as 70,000 years ago. "Paleoanthropological projects must now be launched in South Asia if we hope to document the spread of our species and if we wish to explain how we became behaviorally modern," writes Michael Petraglia, author of a forthcoming article in Current Anthropology.
The expansion of modern humans into South Asia appears to be part of a complex--at times fatal--story. Once modern humans (Homo sapiens) arrived in regions like India, the researchers argue that they would have met indigenous archaic hominids (such as Homo heidelbergensis). "While the precise explanations for the demise of the archaic populations is not yet obvious, it is abundantly clear that they were driven to extinction, likely owing to competition with modern humans over the long term," Petraglia said.
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
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Evidence for these ice deposits comes from high-resolution spectra obtained using the Gemini Observatory’s Adaptive Optics system, ALTAIR coupled with the near-infrared instrument NIRI. The observations, made with the Frederick C. Gillett Gemini North telescope on Hawaii’s Mauna Kea, show the fingerprints of ammonia hydrates and water crystals spread in patches across Charon, and have been described as the best evidence yet for the existence of these compounds on worlds such as Charon.
The observations suggest that liquid water mixed with ammonia from deep within Charon is pushing out to the ultra-cold surface. This action could be occurring on timescales as short as a few hours or days, and at levels that would recoat Charon to a depth of one millimeter every 100,000 years. This discovery could have profound implications for other similar-type worlds in the Kuiper Belt, which is the region of the solar system that extends out beyond the orbit of Neptune and contains a number of small bodies, the largest of which include Pluto and Charon.
“There are a number of mechanisms that could explain the presence of crystalline water ice on the surface of Charon,” said Jason Cook, the PhD student at Arizona State University who led the team of planetary scientists studying the surface of Charon. “Our spectra point consistently to cryovolcanism, which brings liquid water to the surface, where it freezes into ice crystals. That implies that Charon’s interior possesses liquid water.”
About Pluto and Charon
Charon is the companion world to Pluto (or one would say a moon of Pluto, except that Pluto is no longer considered to be a planet). It is one the largest members of the Kuiper Belt, a group of objects that orbit the Sun in the solar system beyond Neptune. The pair has an exceptionally low mass ratio (8:1; the ratio of Earth and the Moon’s masses is 81:1), and is tidally locked in synchronous orbit. Pluto rotates on its axis once every 6.3 days, and Charon takes the same amount of time to make one orbit with respect to Pluto. As a result, they each show the other the same face at all times.
Because Charon is a somewhat typical Kuiper Belt Object for its size, the NIRI observations imply that other KBOs of similar size and composition (containing water ice and ammonia hydrates on their surfaces) could also harbor reservoirs of water deep beneath their surfaces. If so, the team speculates that there could be more liquid water in the Kuiper Belt than on Earth. “If Charon contains a liquid ocean,” said Jason Cook, ”then all Kuiper Belt objects greater than 500 kilometers across have oceans.”
The key to understanding cryovolcanism on Charon, according to Cook, is to look at Charon’s physical makeup. “Charon’s surface is almost entirely water ice,” he said. “So it must have a vast amount of water under the surface, and much of that should be frozen as well. Only deep inside Charon could water be a liquid. Yet, there is fresh ice on the surface, meaning that some liquid water must somehow reach the surface. The ammonia sitting on the surface provides the clue. It’s the ammonia that helps keep some material liquid. It makes it all feasible. Without ammonia the water could not get out there.”
Cryovolcanism in the outer solar system is a fairly common occurrence. Enceladus (a moon of Saturn) and Europa (orbiting Jupiter) both show evidence of water ice oozing or spewing out from beneath the surfaces. So-called “tiger stripes” on Enceladus were first reported in 2006 by planetary scientist Carolyn Porco of the Space Science Institute in Boulder, Colorado. They may be created by geysers that send water ice out through surface cracks. Markings seen on the Uranian moon Ariel in Voyager 2 fly-by images also suggest active cryovolcanism of some kind. Enceladus and Europa are tidally squeezed by the gravitational forces of their giant planets and in some cases by large nearby moons. This forces water out through cracks. Ariel may have been affected by tidal squeezing in the past. By contrast, Kuiper Belt Objects (KBOs) such as Charon, Quaoar, Orcus, and others are not tidally squeezed. Yet, they seem to show evidence of cryovolcanism.
In the case of Charon, it is thought that heat from internal radioactivity creates a pool of melted water mixed with ammonia inside the ice shell. “As some of the subsurface water cools and approaches the freezing point, it expands into the cracks in the ice shell above it,” said Cook. “Due to the expansion, even a small vertical crack of a half a kilometer at the base of the ice shell will allow material to propagate to the outer surface of Charon in a matter of hours, making that the conduit for the water.”
As the water sprays out through the crack, it freezes and immediately “snows” back down to the surface, creating bright ice patches that can be distinguished in near-infrared light. “I half expect that if we ever get to actually SEE a plume going off on Charon, we’d be seeing the process that makes tiger stripes similar to what we see on Enceladus and other frozen worlds,” Cook said. “The real proof will come from the deep-space NASA probe New Horizons, which will arrive at this system in 2015 and send back images that can verify what we’ve seen in our Gemini results.”
The team’s intent was to find evidence of methane, carbon dioxide, ammonia, and a form of ammonia called ammonia hydrate on the surface of Charon, which has also been reported on Quaoar and suspected on at least one other KBO. According to Assistant Professor Steven Desch, Cook’s colleague and thesis advisor at Arizona State University, ammonia hydrates help keep liquid water from freezing solid, making it easier for water to escape from the inside before it turns to ice. “It is literally an antifreeze,” he said, “and like the antifreeze we’re familiar with here on Earth, it depresses the melting point of water.”
Cook and his colleagues concentrated their observations on Charon’s anti-Pluto and sub-Pluto hemispheres, where patches of water ice exist at temperatures between 40-50 Kelvin (-387 to -369 F). They used NIRI to observe at 2.21 and 1.65 microns, wavelengths that reveal the presence of ammonia hydrates and water ice, respectively.
Prior to this work, all observations of Charon made by Cook and others showed crystalline water ice on its surface. Cook’s finding is the only one to date to take two hemispheres and try to estimate the temperatures from the spectra. He notes that more observations are needed to show how temperatures might change with rotation.
“We were using the rotation of Charon to see if these ices are distributed evenly across its surface or are found preferentially at certain longitudes,” Cook said. “Based on measurements from 2001, we knew the ices were there, but we didn¹t have precise locations. What we needed to do was to get high resolution, time-resolved spectra. NIRI coupled with ALTAIR was the best way to do that. And using an 8-meter telescope was a no-brainer. It all came together so well.”
According to Desch, the spectra obtained by Cook and the team are the best evidence yet for the existence of ammonia hydrates on KBOs. “It had been tentatively identified on Charon before by other groups,” he said, “but the lack of spectral resolution hindered its identification. This clinches it. These spectra are also better than those of other KBOs. I've talked to seasoned observers who are convinced for the first time that ammonia hydrates exist on KBOs.”
The next step is to get better spectra of other Kuiper Belt Objects such as Quaoar and Orcus. “Those larger than 500 kilometers across show us crystalline water ice,” Cook said. “But, there’s a whole set of intermediate-sized objects, between 200 and 500 kilometers across that we want to sample to test our ideas. As I think about these other KBOs, I want to look for the ammonia hydrate. I think it has to be out there.”
These results were published in the paper “Near-infrared Spectroscopy of Charon: Possible Evidence for Cryovolcanism on Kuiper Belt Objects” in volume 663 of the Astrophysical Journal, by Jason Cook while at Arizona State University, along with his graduate advisor Steven J. Desch (Arizona State University), the team also included Ted L. Roush (NASA Ames Research Center), and Chad Trujillo and Tom Geballe (Gemini Observatory).
Carol Hughes | EurekAlert!
What happens when we heat the atomic lattice of a magnet all of a sudden?
17.07.2018 | Forschungsverbund Berlin
Subaru Telescope helps pinpoint origin of ultra-high energy neutrino
16.07.2018 | National Institutes of Natural Sciences
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
17.07.2018 | Information Technology
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An ancient Indian manuscript, dating back to the third century, has revealed the oldest recorded use of 'zero' - pushing back one of the greatest breakthroughs in the history of mathematics back by over 500 years, Oxford scientists say.
They found that the text contained hundreds of zeroes, putting the birth of 'zero' or 'nought' as it is also known, at 500 years earlier than scholars first thought.
The text dates back to the third or fourth century, making it the oldest recorded use of the symbol.
However, new carbon dating reveals that the reason why it was previously so difficult for scholars to pinpoint the Bakhshali manuscript's date is because the manuscript, which consists of 70 fragile leaves of birch bark, is in fact composed of material from at least three different periods.
The concept of the symbol as we know and use today, began as a simple dot, which was widely used as a 'placeholder' to represent orders of magnitude in the ancient Indian numbers system - for example 10s, 100s and 1000s, researchers said.
It features prominently in the Bakhshali manuscript, which is widely acknowledged as the oldest Indian mathematical text, they said.
The earliest recorded example of the use of zero was previously believed to be a 9th-century inscription of the symbol on the wall of a temple in Gwalior, Madhya Pradesh.
Although a number of ancient cultures including the ancient Mayans and Babylonians also used the zero placeholder, the dot's use in the Bakhshali manuscript is the one that ultimately evolved into the symbol that we use today, researchers said.
"The creation of zero as a number in its own right, which evolved from the placeholder dot symbol found in the Bakhshali manuscript, was one of the greatest breakthroughs in the history of mathematics," said Marcus du Sautoy, Professor of Mathematics at the University of Oxford.
"We now know that it was as early as the 3rd century that mathematicians in India planted the seed of the idea that would later become so fundamental to the modern world. The findings show how vibrant mathematics have been in the Indian sub-continent for centuries," du Sautoy added. | <urn:uuid:963aa797-2aea-4c51-b7b0-0cd2d89ef9ae> | 3.671875 | 454 | News Article | Science & Tech. | 35.080892 | 95,557,140 |
|Posted: May 20, 2014|
Water caged in buckyballs
|(Nanowerk News) In a new paper in The Journal of Chemical Physics ("Nuclear spin conversion of water inside fullerene cages detected by low-temperature nuclear magnetic resonance"), produced by AIP Publishing, a research team in the United Kingdom and the United States describes how water molecules "caged" in fullerene spheres ("buckyballs") are providing a deeper insight into spin isomers -- varieties of a molecule that differ in their nuclear spin. The results of this work may one day help enhance the analytical and diagnostic power of nuclear magnetic resonance (NMR) and magnetic resonance imaging (MRI).|
2[email protected]60" width="200" border=0 style="margin-bottom:0.5em;">
Studies of the molecular structure of the water-endofullerene H2[email protected]60 may enhance laboratory nuclear magnetic resonance (NMR) and clinical magnetic resonance imaging (MRI). Water molecules can exist as one of two isomers depending on how the spins of their two hydrogen atoms are oriented: ortho, where the spins are parallel and have a spin number of 1, and para, where the spins are antiparallel and have a spin number of 0. Scientists believe that any given molecule can transform from ortho- into para- spin states and vice versa, a process known as nuclear spin conversion.
"Currently, mechanisms for this conversion are not completely understood, nor how long it takes the molecules to transform from one spin isomer to the other," said Salvatore Mamone, a post-doctoral physicist at the University of Southampton and lead author on the JCP paper. "To study this, we had to figure out how to reduce the strong intermolecular interactions that are responsible for aggregation and lower the rotational mobility of the water molecules."
The answer was to use chemical reactions to open a hole in fullerene (C60, also known as a buckyball) spheres, inject water molecules and then close the "cages" to form a complex referred to as H2[email protected]60. "At the end of this synthetic preparation nicknamed ‘molecular surgery,' we find that 70 to 90 percent of the cages are filled, giving us a significant quantity of water molecules to examine," Mamone said. "Because the [water] molecules are kept separated by the cages, there is a large rotational freedom that makes observation of the ortho and para isomers possible."
|In their experiment, the researchers quickly cooled the individual H2[email protected]60 samples from 50 Kelvin (minus 223 degrees Celsius) to 5 K (minus 268 degrees Celsius) and then monitored their NMR signal every few minutes over several days.|
|"As the observed NMR signal is proportional to the amount of ortho-water in the sample [para-water with its spin number of 0 is "NMR silent"], we can track the percentages of ortho and para isomers at any time and any temperature," Mamone explained. "At 50 K, we find that 75 percent of the water molecules are ortho, while at 5 K, they become almost 100 percent para. Therefore, we know that after the quick temperature jump, equilibrium is restored by conversion from ortho to para—and we see that conversion in real time."|
|A surprising outcome of the experiment was that the researchers observed a second-order rate law in the kinetics of the spin conversion which proves that pairs of molecules have to interact for conversion to occur. "Previous studies have speculated that other nuclear spins can cause conversion but we found this not to be the case for H2[email protected]60," Mamone said.|
|Next up, the research team plans to study the roles of isomer concentrations and temperature in the conversion process, the conversion of para-water to ortho ("back conversion"), how to detect single ortho- and para-water molecules on surfaces, and spin isomers in other fullerene-caged molecules.|
|Source: American Institute of Physics|
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Valley networks branching across the Martian surface leave little doubt that water once flowed on the Red Planet. But where that ancient water came from — whether it bubbled up from underground or fell as rain or snow — is still debated by scientists. A new study by researchers at Brown University puts a new check mark in the precipitation column.
Mars from the Odyssey spacecraft
Water-carved valleys on Mars appear to have been caused by runoff from precipitation, likely meltwater from snow. Early Martian precipitation would have fallen on mountainsides and crater rims. Credit: Images from NASA
The study finds that water-carved valleys at four different locations on Mars appear to have been caused by runoff from orographic precipitation — snow or rain that falls when moist prevailing winds are pushed upward by mountain ridges. The new findings are the most detailed evidence yet of an orographic effect on ancient Mars and could shed new light on the planet’s early climate and atmosphere.
A paper describing the work has been accepted by Geophysical Research Letters and published online in June.
Kat Scanlon, a geological sciences graduate student at Brown, led the research and is well-acquainted with the orographic effect. She did graduate work in meteorology in Hawaii, which is home to a quintessential orographic pattern. Moist tropical winds from the east are pushed upward when they hit the mountains of Hawaii’s big island. The winds lack the kinetic energy to reach the mountain summit, so they dump their moisture on the eastern side of the island, making parts of it a tropical jungle. The western side, in contrast, is nearly a desert because it sits in a rain shadow cast by the mountain peak.
Scanlon thought similar orographic patterns might have been at play on early Mars and that the valley networks might be an indicator. “That’s what immediately came to mind in trying to figure out if these valleys on Mars are precipitation related,” she said.
The researchers, including Jim Head, professor of geological sciences, started by identifying four locations where valley networks were found along tall mountain ridges or raised crater rims. To establish the direction of the prevailing winds at each location, the researchers used a newly developed general circulation model (GCM) for Mars. The model simulates air movement based on the gas composition scientists think was present in the early Mars atmosphere. Next, the team used a model of orographic precipitation to determine where, given the prevailing winds from the GCM, precipitation would be likely to fall in each of the study areas.
Their simulations showed that precipitation would have been heaviest at the heads of the densest valley networks. “Their drainage density varies in the way you would expect from the complex response of precipitation to topography,” Scanlon said. “We were able to confirm that in a pretty solid way.”
The atmospheric parameters used in the GCM are based on a new comprehensive general circulation model that predicts a cold climate, so the precipitation modeled in this study was snow. But this snow could have been melted by episodic warming conditions to form the valley networks, and indeed some precipitation could have been rain during this period, Scanlon and Head say.
“The next step is to do some snowmelt modeling,” she said. “The question is how fast can you melt a giant snowbank. Do you need rain? Is it even possible to get enough discharge [to carve the valleys] with just the snowmelt?”
With the knowledge from this study that precipitation was important in carving the valleys, the answers to those additional questions could provide important insight into the climate on Mars billions of years ago.
Editors: Brown University has a fiber link television studio available for domestic and international live and taped interviews, and maintains an ISDN line for radio interviews. For more information, call (401) 863-2476.
Global study of world's beaches shows threat to protected areas
19.07.2018 | NASA/Goddard Space Flight Center
NSF-supported researchers to present new results on hurricanes and other extreme events
19.07.2018 | National Science Foundation
A new manufacturing technique uses a process similar to newspaper printing to form smoother and more flexible metals for making ultrafast electronic devices.
The low-cost process, developed by Purdue University researchers, combines tools already used in industry for manufacturing metals on a large scale, but uses...
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
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The Atmospheric Infrared Sounder (AIRS) instrument that flies aboard NASA's Aqua satellite provided both a visible and an infrared look at the severe weather that moved into Maryland on June 1 and generated an astounding number of tornadoes – nine in all.
Aqua passed over Maryland on June 1 around 18:53 UTC (2:53 p.m. EDT) and AIRS captured data on temperature and cloud heights. The infrared imagery showed that the major activity was located in West Virginia and heading eastward toward Maryland. When cloud temperatures get colder, it means that clouds are getting higher. Building clouds indicate a lot of "uplift" in the atmosphere and stronger thunderstorms.
Ed Olsen of the AIRS Team at NASA's Jet Propulsion Laboratory, Pasadena, Calif. said that the AIRS imagery showed "The center of most intense activity over West Virginia appears to have cloud top temperatures between -27 and -45 Fahrenheit (-33.1 and -43.1 Celsius / 230 and 240 Kelvin), meaning that the cloud tops (assuming U.S. Standard Atmosphere) are between (4.6 and 5.6 miles) 7.5 and 9 kilometers high."
The data from the AIRS instrument is also used to create an accurate 3-D map of atmospheric temperature, water vapor and clouds, all of which are helpful to forecasters.
NOAA's GOES-13 satellite was providing real-time visible imagery of the severe weather outbreak when tornadoes were touching down around Maryland on June 1. The NASA GOES Project, located at NASA's Goddard Space Flight Center in Greenbelt, Md. combined the GOES imagery to create an animation of the severe weather outbreak. The animation that runs almost eight seconds shows the movement of the severe storms from 1:45 p.m. to 7:45 p.m. EDT (1745 UTC to 2345 UTC). The colorized full resolution uses the GOES visible data of the clouds, overlaid on a U.S. map created by imagery from the Moderate Resolution Spectroradiometer instrument (MODIS), an instrument that flies onboard both the NASA Aqua and Terra satellites.
The animation shows a cold front approaching from the west spawned severe storms along the U.S. East Coast, including 9 weak tornadoes in Maryland around sunset. From the GOES viewpoint, all that surface action is covered by cloud tops.
Baltimore Meteorologist Justin Berk compiled a listing of the individual tornadoes. The ten tornadoes include: An EF-1 tornado with 90 mph winds in Pleasant Hills, Harford County; An EF-0 tornado started near Fort Meade and moved to BWI Marshall Airport; another tornado (not rated yet) in Gamber, Carroll County; an EF-O in Centreville in Queen Anne's County, Md. ; Two possible EF-0 tornadoes in Damascus, Montgomery County; An EF-0 at Springdale, Prince George's County (just outside the Washington, D.C. beltway); An EF-1 touched down in Watersville, Howard County; another EF-0 tornado touched down in Mount Airy in Carroll County; and another tornado (not yet rated) made an appearance in Simpsonville, Howard County.
For the complete listing of tornado reports, visit:http://www.spc.noaa.gov/climo/reports/120601_rpts.html Rob Gutro
Rob Gutro | EurekAlert!
Global study of world's beaches shows threat to protected areas
19.07.2018 | NASA/Goddard Space Flight Center
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You have to look heavenward through a telescope to see the object of her fascination--to pale stars called white dwarfs, their brilliance faded because all of their nuclear fuel has been burned up.
A white dwarf is a star that is “dying,” cooling down in the twilight of its life. It's what the sun will become in about 4 billion years, according to Provencal.
Starting Wednesday, March 26, Provencal--who is an assistant professor of physics and astronomy at the University of Delaware, director of the Delaware Asteroseismic Research Center (DARC), and resident astronomer at Mt. Cuba Astronomical Observatory in Greenville, Del.--will be coordinating some of the world's largest telescopes in a five-week-long “international observing run,” focusing on a white dwarf known as IU Vir in the constellation Virgo. The star's coordinates are 14012-1446.
The observing run will be conducted by the Whole Earth Telescope (WET), a worldwide network of observatories that work together to obtain continuous measurements of “pulsating” stars. Such stars change their shape or surface temperature as waves of energy travel through them. They are the basis of asteroseismology, a fledgling science that examines “starquakes” just as seismologists monitor earthquakes.
WET was initiated in 1986 by astronomers at the University of Texas and later was transferred to Iowa State University. Three years ago, the coordination of WET moved to the University of Delaware through the leadership of Provencal and Harry Shipman, the Annie Jump Cannon Professor of Astronomy at UD, and with the financial support of the Crystal Trust Foundation.
The upcoming observing run will involve more than 20 of WET's observatories, including one of the largest telescopes on the planet--the Southern African Large Telescope (SALT) in Sutherland, South Africa. It has a 10-by-11-meter (32-by-36 foot) hexagonal, segmented mirror and can record stars, galaxies and quasars a billion times too faint to be seen by the unaided eye--“as faint as a candle flame at the distance of the moon,” according to its Web site.
From March 26 through May 1, the lenses of these major telescopes will focus on IU Vir to provide 24/7 coverage. Like an international relay team, observers at Mt. Cuba in Delaware will study the white dwarf until sunrise, and then observers at Macdonald Observatory in Fort Davis, Texas, and at Kitt Peak National Observatory in Tucson, Arizona, will stand watch while the star is in their sky, followed by observers in Hawaii, then New Zealand, Australia, China and so on, around the globe.
All of the data will be transmitted to UD for analysis. Provencal and colleagues Susan Thompson, assistant director of DARC, and Teresa Holton, program coordinator, will operate the command center during the observing run, monitoring the observatories and their daily data transmissions via a Web site.
As Provencal reminds us, when we look up at the stars, the light we see has traveled millions of miles through space. It's the only artifact we have of the stars, yet this light carries with it a lot of information, allowing scientists to determine such characteristics as a star's surface composition, temperature and motion toward or away from us.
“Pulsating stars such as the white dwarf oscillate, and how they oscillate lets us determine what they look like inside,” Provencal explains. “Let's say you have a silver bell, and you ring it. It will make a certain sound. Now you have an aluminum bell that is the same shape as the silver bell. If you ring it, it won't sound like the silver bell. It will have its own tone. Stars do that, too. I like to think of our work as listening to the 'music of the stars,'” she says, smiling.
Besides giving scientists more detailed information about IU Vir, the data collected will include clues as to what is going on inside the sun because a white dwarf is the exposed core of what was once a star like the sun, according to Provencal.
“What we do might be called 'forensic astronomy,'” Provencal says. “If we can dig around in the innards of a white dwarf, and determine what it ate for lunch, how much it ate, and how quickly it ate, we can understand what is going on inside our own sun much better. We'll look at the pulsations of the star, take the frequencies at which it pulsates, and develop a model of it. In that way, this dead star which was once like the sun will help improve our understanding of the sun.”
Also, Provencal says that white dwarfs are good timekeepers, and as such, hold clues about the age of the cosmos.
A white dwarf is in the center of planetary nebula NGC6751. Near the ring of gas is a foreground star.“Once a white dwarf forms, all it does is sit and cool, so we can measure the temperature of a white dwarf, and, using some theoretical understandings, figure out how long it took the star to cool to that temperature, and hence determine how old it is,” Provencal says. “The coolest white dwarf we know of is about 2,500 degrees,” she notes. “This corresponds to an age for the galaxy of about 10 billion years.”
For more information about UD's Delaware Asteroseismic Research Center, visit [www.physics.udel.edu/darc/index.html].
Article by Tracey Bryant
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
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
20.07.2018 | Power and Electrical Engineering
20.07.2018 | Information Technology
20.07.2018 | Materials Sciences | <urn:uuid:4360b4e1-7808-448a-a185-3f08f48087c1> | 3.40625 | 1,303 | Knowledge Article | Science & Tech. | 54.668365 | 95,557,175 |
Management of Freshwater Biodiversity: Crayfish as Bioindicators (BOK)
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Integrating research into freshwater biodiversity and the role of keystone species, this fascinating book presents freshwater crayfish as representatives of human-exacerbated threats to biodiversity and conservation. It uses examples from these and other large decapod invertebrates to explore how communities function and are controlled, alongside the implications of human demands and conflicts over limited resources, notably the severe impacts on biodiversity. The discussion is structured around three key topics - the present situation of crayfish in world freshwater ecosystems, the applications of science to conservation management and knowledge transfer for successful crayfish management. It outlines the historic exploitation of crayfish, addressing the problems caused by invasive alien forms and explaining the importance of correct identification when dealing with conservation issues. Offering a global perspective on freshwater systems, the book ultimately highlights how the conservation of such large and long-lived species will help protect ecosystem quality in the future.
|Utgitt||2011||Forfatter||Catherine Souty-Grosset, Julian Reynolds|
CAMBRIDGE UNIVERSITY PRESS
|Antall sider||384||Dimensjoner||17,4cm x 24,7cm x 2,3cm|
|Vekt||940 gram||Leverandør||Bertram Trading Ltd|
|Emner og form||Ecological science, the Biosphere, Freshwater biology, Biodiversity| | <urn:uuid:83ef644a-f8e0-49f8-a646-0c57dfae8387> | 2.859375 | 320 | Product Page | Science & Tech. | -11.492227 | 95,557,177 |
Section 2.2: Axiomatic Systems. Math 333 – Euclidean and Non-Euclidean Geometry Dr. Hamblin. What is an Axiomatic System?. An axiomatic system is a list of undefined terms together with a list of axioms. A theorem is any statement that can be proved from the axioms.
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Math 333 – Euclidean and Non-Euclidean Geometry
Finding a model where Axioms 2-4 are true and Axiom 1 is false shows that the if-then statement is false! | <urn:uuid:da66361a-537c-4d4f-9419-650c6b290bb8> | 3.125 | 186 | Truncated | Science & Tech. | 57.803329 | 95,557,179 |
As discussed in Raymond Chang’s introductory textbook “Chemistry,” a mole is a measure of molecules, equal to approximately 6.022x10^23 molecules, where the caret ^ refers to exponentiation. Using the ideal gas formula, you can find the number of moles of carbon dioxide (CO2) in a container if you know the other needed parameters and conditions. Above 150 pounds per square inch (PSI), or around 10 times normal atmospheric pressure, the ideal gas formula starts losing accuracy and the Van der Waals formula becomes increasingly preferable.
Write the temperature of the CO2 in degrees Kelvin (K) by adding 273.15 to the number of degrees Celsius.
Write the volume of the CO2 container in liters (L). A liter is about a quart. Convert gallons into liters by multiplying by 3.7854.
Write the pressure of the container in atmospheres (atm). An atmosphere is about the air pressure at sea level. Convert PSI into atm by multiplying by 0.06804596.
Calculate the number of moles of CO2 by the formula n=PV/RT, where P is the pressure from Step 3, V is the volume from Step 2, T is the temperature from Step 1 and R is a proportionality constant equal to 0.0821 L atm / K mol. All the units except for moles will cancel out in the end.
Check your work against an online ideal gas calculator (see Resources). | <urn:uuid:e486af15-54b3-49e2-ac81-5548149aee98> | 4.03125 | 313 | Tutorial | Science & Tech. | 61.747605 | 95,557,191 |
Energy is the capability of a body to do work. It can take many forms: heat, light, sound, electricity, magnetism, nuclear and so on. However, our concern is with mechanical energy. Mechanical energy is of two types: kinetic energy and potential energy. Kinetic energy is the energy of a body by virtue of its motion. Potential energy is the energy of a body by virtue of its position. A body is held so that it is stationary and then released; if it moves then it possesses potential energy. Examples include a stone dropped out of a window or the release of a stretched catapult. In order to develop results systematically from our knowledge of forces, we shall first define work.
KeywordsPotential Energy Maximum Speed Mechanical Energy Frictional Resistance Line Integral
Unable to display preview. Download preview PDF. | <urn:uuid:c54a94bc-6e96-4f42-90a7-2b3e31ceb644> | 3.515625 | 168 | Truncated | Science & Tech. | 34.25641 | 95,557,201 |
A research team based at the University of Chicago may have found a way to manipulate cell suicide, also known as programmed cell death, a normal process that regulates cell number but that goes awry in chronic inflammatory disorders, cancer and other diseases.
In the 12 Nov. 2004 issue of the journal Cell, the scientists show that a key step in the process of preventing cell suicide is the induction of ferritin heavy chain (FHC), a protein that collects and hoards iron. By sequestering iron -- which cells with suicidal tendencies need to make the harmful substances that induce death -- FHC prevents cellular suicide.
This finding suggests that drugs that modulate FHC or iron metabolism could provide a new and effective approach to anti-inflammatory therapy without the side effects, such as weakening the immune system, that come with current treatments. "In a long and complicated biochemical chain, this is one of the final links, which is exactly what we want," said study author Guido Franzoso, M.D., Ph.D., associate professor in the Ben May Institute for Cancer Research at the University of Chicago. "If we tamper with the front end, it changes everything, but boosting or blocking a downstream component allows us to select for a specific response."
John Easton | EurekAlert!
Colorectal cancer risk factors decrypted
13.07.2018 | Max-Planck-Institut für Stoffwechselforschung
Algae Have Land Genes
13.07.2018 | Julius-Maximilians-Universität Würzburg
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
13.07.2018 | Event News
13.07.2018 | Materials Sciences
13.07.2018 | Life Sciences | <urn:uuid:75ee2250-6e70-4223-88ad-b1cb90ada955> | 2.65625 | 904 | Content Listing | Science & Tech. | 43.220849 | 95,557,215 |
How to simulate printf's %p format when using std::cout?
Depending on wheter or not you want to use more formatting options printf gives, you could consider using sprintf
By it, you could format a string just like you'd do with printf, and afterwards print it out with
However, this would involve using a temporary char array so the choice depends.
unsigned char *teta = ....; ... char formatted[ 256 ]; //Caution with the length, there is risk of a buffer overflow sprintf( formatted, "data at %p\n", teta ); std::cout << formatted;
unsigned char *teta = ....; ... printf("data at %p\n", teta); // prints 0xXXXXXXXX
How can I print variable address using
iostreams? Is there a
std::??? feature like
std::hex to do this kind of conversion (address -> string), so
std::cout << std::??? << teta << std::endl will print that address?
(no sprintf's, please ;))
The type of
char*, and so
cout<< thinks that you want to print a string.
Point p2 = p1;
you simply copy the values of p2 onto p1 (most likely). The memory is independent. If you did instead:
Point* p2 = &p1;
then p2 will be a pointer onto p1 (printing its value will give you the begining of the memory block, you could then try the sizeof to get the size of the block).
Where is `%p` useful with printf?
They do not do the same thing. The latter
printf statement interprets
b as an
unsigned int, which is wrong, as
b is a pointer.
unsigned ints are not always the same size, so these are not interchangeable. When they aren't the same size (an increasingly common case, as 64-bit CPUs and operating systems become more common),
%x will only print half of the address. On a Mac (and probably some other systems), that will ruin the address; the output will be wrong.
%p for pointers.
You cannot depend on
%p displaying a
0x prefix. On Visual C++, it does not. Use
%#p to be portable. | <urn:uuid:1869bad1-4dcc-47be-92b9-fa4a35ccc512> | 3.625 | 495 | Q&A Forum | Software Dev. | 84.00708 | 95,557,233 |
Behind the scene: creating and operating the Species Observations database – an important Citizen Science system
The Species Observations reporting system is an Internet database that grew out of a cooperative effort between the Norwegian Biodiversity Information Centre and SABIMA, the Norwegian Biodiversity Network, and five of the network’s member societies.
The system named Artsobservasjoner was first released in May 2008. It allows any member of the public to report georeferenced sightings and observations for all species, from fungi to plants, insects, fish and birds.
Reporters are encouraged to document their observations with as much evidence as possible, including photographs or other documentation.
Users and managers provide checks
In the Species Observations system the reporter determines what is entered into the database and owns the reported sightings or findings of species afterwards.
All findings are first published and then quality checked afterwards by managers from the appropriate respective societies. A key aspect of the system allows observations to be corrected by other users through direct comments to the person who has made the report.
SABIMA itself has three mapping coordinators who organize the quality assurance of the data collected as part of the Species Observations system. More than 150 voluntary species experts in the organizations are involved in data validation.
These coordinators also provide user support, suggest updated user interfaces and functions, and encourage field biologists to use the service.
One mapping coordinator works with botany and mycology (with the Norwegian Botanical Society and the Fungi and Useful Plants Federation) and the other with zoology (with the Norwegian Entomological Society and the Norwegian Zoological Society). The third (the Norwegian Bird Society) is organizing the quality control of the huge amount of bird sightings, where more than 100 persons are validating county wise.
The mapping coordinators work to stimulate, educate and coordinate the hundreds of amateur and hobby biologists who pursue their passion by collecting and mapping plants and animals in Norwegian nature.
Seminars, guidance and grants
A key focus of the mapping coordinators is to encourage these amateurs to enter their data into the national report system.
The accumulation of these observations and the larger patterns that emerge from the data make the volunteer efforts very useful in monitoring and as a knowledge base for land management in Norway.
The mapping coordinators facilitate this through seminars, guidance, small grants, subject matter support and personal follow-up with field biologists. | <urn:uuid:0c5dc036-f392-4d6d-b68e-40791cf50474> | 2.90625 | 495 | Knowledge Article | Science & Tech. | 12.111407 | 95,557,252 |
Species Detail - Yellow Club (Clavulinopsis helvola) - Species information displayed is based on all datasets.
Terrestrial Map - 10kmDistribution of the number of records recorded within each 10km grid square (ITM).
Marine Map - 50kmDistribution of the number of records recorded within each 50km grid square (WGS84).
Clavaria dissipabilis, Clavaria helvola, Clavaria inaequalis sensu auct.
28 August (recorded in 2008)
10 November (recorded in 2007)
National Biodiversity Data Centre, Ireland, Yellow Club (Clavulinopsis helvola), accessed 20 July 2018, <https://maps.biodiversityireland.ie/Species/158154> | <urn:uuid:0c62d3c7-d6d0-44c6-b2d7-7779f78b1f2b> | 2.625 | 164 | Structured Data | Science & Tech. | 27.065833 | 95,557,266 |
Earthworms perform many essential and beneficial functions in the soil ecosystem, including soil structure improvement and nutrient mineralization. However the earthworms’ ability to perform these crucial functions can be suppressed when they are exposed to toxic substances.
A Baylor University geology researcher, along with scientists from Rice University, tested a new soil additive called biochar for its effects on the common earthworm. The researchers found that wetting the biochar before applying it to the soil mitigates the harmful effects of biochar to earthworms and the earthworms’ avoidance of soil with biochar.
“Because of the high potential for widespread application, it is essential to proactively assess and mitigate any unintended consequences associated with biochar soil enrichment,” said study co-author Dr. Bill Hockaday, assistant professor of geology at Baylor. “The results show us that depending on rainfall patterns and irrigation, wetting biochar either before or immediately after soil application would be needed to prevent the disappearance of earthworms and enable their beneficial effects on plants.”
The results appeared on-line in the journal Soil Biology and Biochemistry.
Biochar is of increasing interest because of concerns about climate change caused by emissions of carbon dioxide and other greenhouse gases. It is a byproduct of renewable energy and fuel production from plant materials like forest wastes and crop residues. Biochar is a form of charcoal that enhances soil fertility and plant growth by increasing soil water and nutrient retention, and can store carbon in the soil for hundreds of years.
The researchers found that earthworms avoided soil enriched with dry biochar, and when they were exposed, their weight decreased. After performing several different tests, the researchers found that insufficient moisture was a key factor affecting earthworm behavior in soil enriched with dry biochar. The researchers also found that biochar did not affect earthworm reproduction.
“Most importantly, we are the first to demonstrate that biochar did not stress the immune system of a very sensitive soil organism,” said Dong Li, study co-author and a graduate student at Rice. “This is an important step forward for a very promising strategy in combating climate change.”
Matt Pene, Assistant Director of Media Communications, 254-710-4656
Matt Pene | Newswise Science News
Innovative genetic tests for children with developmental disorders and epilepsy
11.07.2018 | Christian-Albrechts-Universität zu Kiel
Oxygen loss in the coastal Baltic Sea is “unprecedentedly severe”
05.07.2018 | European Geosciences Union
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
19.07.2018 | Earth Sciences
19.07.2018 | Power and Electrical Engineering
19.07.2018 | Materials Sciences | <urn:uuid:bf23e1ea-c4db-4ac7-b7c8-1886b8140534> | 3.78125 | 1,117 | Content Listing | Science & Tech. | 35.218365 | 95,557,268 |
Global warming refers to the rising average temperature of the earth’s atmosphere and oceans, which started to increase in the late 19th century and is projected to keep going up. If we go for the scenario of 20th century in relation to global warming, since the early period of this century, Earth’s average surface temperature has increased by about 1.4 F i.e. 0.8oC. This finding is, with about two thirds of the increase occurring since 1980. Warming of the climate system is unequivocal and scientists are more than ninety percent certain that most of it is caused by increasing concentrations of green house gases produced by human activities such as deforestation and burning fossil fuels. The national science academies have also recognized these findings. An increase in global temperature will cause sea levels to rise and will change the amount and pattern of precipitation and a probable expansion of subtropical deserts. If global mean temperature increase by 4oC above pre-industrial levels, the limits for adaptation for natural systems will largely be exceeded. Hence the ecosystem services upon which human livelihoods depend would not be preserved. The effect of global warming in India vary from submergence of low lying islands and coastal lands to the melting of glaciers in the Indian Himalayas, threatening the volumetric flow rate of many of the most important rivers of the India. Global warming shows some deadliest effects. Polar ice caps melting due to global warming will raise sea levels. Ice caps will throw the global ecosystem out of balance. Temperature rises and changing landscapes will endanger several species of animals. If Ice caps melt, the only reflector is the ocean; darker colours absorb sunlight, further warming the Earth. Anthropogenic global warming has economic consequences. Due to global warming, there is increased probability and intensity of droughts and heat waves. As the temperature of oceans rises, so will the probability of more frequent and stronger hurricanes. In future, towns of India like Mumbai, Chennai etc. may be covered with water due to global warming as such towns are situated on the bank of sea. As a consequence of this, the population of the country will decrease. | <urn:uuid:6b769ecc-5a14-4ef0-b166-ebed76de5fbe> | 3.953125 | 430 | Academic Writing | Science & Tech. | 39.492316 | 95,557,276 |
For the past 2 million years, the size of the human brain has tripled, growing much faster than other mammals. Examining the reasons for human brain expansion, University of Missouri researchers studied three common hypotheses for brain growth: climate change, ecological demands and social competition. The team found that social competition is the major cause of increased cranial capacity.
To test the three hypotheses, MU researchers collected data from 153 hominid (humans and our ancestors) skulls from the past 2 million years. Examining the locations and global climate changes at the time the fossil was dated, the number of parasites in the region and estimated population density in the areas where the skulls were found, the researchers discovered that population density had the biggest effect on skull size and thus cranial capacity.
"Our findings suggest brain size increases the most in areas with larger populations and this almost certainly increased the intensity of social competition," said David Geary, Curator's Professor and Thomas Jefferson Professor of Psychosocial Sciences in the MU College of Arts and Science. "When humans had to compete for necessities and social status, which allowed better access to these necessities, bigger brains provided an advantage."
The researchers also found some credibility to the climate-change hypothesis, which assumes that global climate change and migrations away from the equator resulted in humans becoming better at coping with climate change. But the importance of coping with climate was much smaller than the importance of coping with other people.
"Brains are metabolically expensive, meaning they take lots of time and energy to develop and maintain, making it so important to understand why our brains continued to evolve faster than other animals," said Drew Bailey, MU graduate student and co-author of the study. "Our research tells us that competition, whether healthy or not, sets the stage for brain evolution."
The study, "Hominid Brain Evolution," recently was published in Human Nature and co-authored by Geary and Bailey.
Jeffrey Beeson | EurekAlert!
Innovative genetic tests for children with developmental disorders and epilepsy
11.07.2018 | Christian-Albrechts-Universität zu Kiel
Oxygen loss in the coastal Baltic Sea is “unprecedentedly severe”
05.07.2018 | European Geosciences Union
A new manufacturing technique uses a process similar to newspaper printing to form smoother and more flexible metals for making ultrafast electronic devices.
The low-cost process, developed by Purdue University researchers, combines tools already used in industry for manufacturing metals on a large scale, but uses...
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
20.07.2018 | Power and Electrical Engineering
20.07.2018 | Information Technology
20.07.2018 | Materials Sciences | <urn:uuid:a34c9e58-9b55-4b48-9b80-a263cbec7837> | 3.625 | 989 | Content Listing | Science & Tech. | 33.386738 | 95,557,285 |
Statistical probablity is the only thing we can know exactly.Often students get bogged down in the fact that they don't "understand" how and why radioactive elements decay and miss the whole point of this exercise.Furthermore, Parentium and Daughterium are so different in chemical properties that they don't otherwise occur together.If there were such a pair of isotopes, radiometric dating would be very simple.However, the crater number relation must be calibrated against something with a known age.To measure the passage of long periods of time, scientists take advantage of a regularity in certain unstable atoms.
Since God is the Creator of all things (including science), and His Word is true (“), the true age of the earth must agree with His Word.
Imagine we have an undiscovered element, Parentium, that has a radioactive isotope, Parentium-123, which decays to stable Daughterium-123.
This is the only way Parentium-123 decays, and there is no other source of Daughterium-123.
Or you can tell that certain parts of the Moon's surface are older than other parts by counting the number of craters per unit area.
The old surface will have many craters per area because it has been exposed to space for a long time. If you assume that the impact rate has been constant for the past several billion years, then the number of craters will be proportional to how long the surface is exposed. | <urn:uuid:521ae470-9a9b-4dd3-9ac7-e8408192ff31> | 3.953125 | 302 | Spam / Ads | Science & Tech. | 45.684442 | 95,557,293 |
A shape and space game for 2,3 or 4 players. Be the last person to be able to place a pentomino piece on the playing board. Play with card, or on the computer.
Slide the pieces to move Khun Phaen past all the guards into the position on the right from which he can escape to freedom.
Use the blue spot to help you move the yellow spot from one star to the other. How are the trails of the blue and yellow spots related?
Sort the frieze patterns into seven pairs according to the way in which the motif is repeated.
Why not challenge a friend to play this transformation game?
This article describes the scope for practical exploration of tessellations both in and out of the classroom. It seems a golden opportunity to link art with maths, allowing the creative side of your. . . .
Explore the effect of reflecting in two parallel mirror lines.
Overlaying pentominoes can produce some effective patterns. Why not use LOGO to try out some of the ideas suggested here?
See the effects of some combined transformations on a shape. Can you describe what the individual transformations do?
What is the relationship between these first two shapes? Which shape relates to the third one in the same way? Can you explain why?
What are the coordinates of this shape after it has been transformed in the ways described? Compare these with the original coordinates. What do you notice about the numbers?
Does changing the order of transformations always/sometimes/never produce the same transformation?
Numbers arranged in a square but some exceptional spatial awareness probably needed.
These images are taken from the Topkapi Palace in Istanbul, Turkey. Can you work out the basic unit that makes up each pattern? Can you continue the pattern? Can you see any similarities and. . . .
Draw a square. A second square of the same size slides around the first always maintaining contact and keeping the same orientation. How far does the dot travel?
Some local pupils lost a geometric opportunity recently as they surveyed the cars in the car park. Did you know that car tyres, and the wheels that they on, are a rich source of geometry?
Explore the effect of combining enlargements.
How will you decide which way of flipping over and/or turning the grid will give you the highest total?
Investigate what happens to the equation of different lines when you translate them. Try to predict what will happen. Explain your findings.
A gallery of beautiful photos of cast ironwork friezes in Australia with a mathematical discussion of the classification of frieze patterns.
Patterns that repeat in a line are strangely interesting. How many types are there and how do you tell one type from another? | <urn:uuid:dc5c28bd-4233-4b6d-9afb-a99e4cdb9829> | 3.109375 | 563 | Content Listing | Science & Tech. | 56.091134 | 95,557,324 |
Peter Majewski and Chiu Ping Chan of the Ian Wark Research Institute, at the University of South Australia, explain that the availability of drinking quality water is fast becoming a major socio-economic issue across the globe, especially in the developing world. However, water purification technology is often complicated, requires sophisticated equipment and is expensive to run and maintain. Moreover, it usually requires a final costly disinfection stage. The Australian team suggests that nanotechnology could provide a simple answer to the problem.
The researchers have investigated how silica particles can be coated easily with a nanometre-thin layer of active material based on a hydrocarbon with a silicon-containing anchor. The coating is formed through a chemical self-assembly process so involves nothing more than stirring the ingredients to make the active particles.
These active particles, so called Surface Engineered Silica (SES), were then tested to demonstrate that they could remove biological molecules, pathogens such as viruses like the Polio virus, bacteria like Escherichia coli, and Cryptosporidium parvum, which is a waterborne parasite.
"The results clearly show that organic species can efficiently be removed at pH ranges of drinking water by stirring the coated particles in the contaminated water for up to one hour and filtering the powder," the researchers say. They point out that the filtration process occurs through an electrostatic attraction between the pathogens and the surface engineered particles.
The recent report entitled 'Water for People - Water for Life' of the World Water Assessment Program of the UNESCO says that more than 6000 people die every day due to water-related diseases, including diarrhoea, worm infections, and infectious diseases. In addition, organic pollutants from industrial waste water from pulp and paper mills, textiles and leather factories, steel foundries, and petrochemicals refineries, are a major cause of illness in parts of the world where regulations do not necessarily protect people from such industrial outflows. The team's nanotech approach to water purification could help prevent disease and poisoning for potentially millions of people.
Albert Ang | alfa
Upcycling of PET Bottles: New Ideas for Resource Cycles in Germany
25.06.2018 | Fraunhofer-Institut für Betriebsfestigkeit und Systemzuverlässigkeit LBF
Dry landscapes can increase disease transmission
20.06.2018 | Forschungsverbund Berlin e.V.
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
16.07.2018 | Physics and Astronomy
16.07.2018 | Transportation and Logistics
16.07.2018 | Agricultural and Forestry Science | <urn:uuid:4e0de41b-c4da-4bf0-a846-62b25e11b4be> | 3.4375 | 1,085 | Content Listing | Science & Tech. | 31.892357 | 95,557,329 |
Shaken and Stirred: Scaling Up Bioreactors’ Fluid Dynamics
Bioreactors are widely used to produce different therapeutics in the biopharmaceutical and regenerative medicine industries. Drug development relies on small multi-well plates shaken around an orbital diameter, while production-scale bioreactors are agitated by stirring. These different methods yield different fluid dynamics, making it difficult to scale lab findings to industry.
A team of researchers from University College London is starting to bridge this gap by applying analytical techniques for stirred bioreactors to the fluid dynamics of orbitally shaken bioreactors (OSBs). Combining vertical and horizontal measurements through particle image velocimetry, the group reconstructed a 3-D model of OSB flow and determined key features of the coherent structures inside OSBs. They publish their work this week in Physics of Fluids, from AIP Publishing.
“In this work, we used two different decomposition techniques, which allowed us to identify dominant modes of oscillation of the flow inside in the reactor,” said Andrea Ducci, an author on the paper. “The first pair of modes controls the free surface motion and therefore the aeration of cells, while the second pair is related to the bulk flow of the tank.”
Shaken bioreactors offer low shear stresses and well-defined free surfaces of oxygen transfer, a gentle swirling that is vital for culturing mammalian cells. Proper orthogonal decomposition (POD), ranks modes by energy, while dynamic mode decomposition (DMD), orders them by frequency. Ducci said that their team is using these techniques to analyze OSBs for the first time.
The researchers used Finite-Time Lyapunov Exponent (FTLE) analysis to assess how well the reactor disperses nutrients. In FTLE, the paths of adjacent particles are stitched together from a series of time-delayed images. The further the particles are after a period of time, the better the mixing.
The team measured the flow in the OSBs at two different Froude numbers (Fr), dimensionless quantities that relate flow inertia to gravity and are used to predict when the bioreactor flow is in or out of phase with its orbit.
“If you keep scaling parameters, such as the Froude number, constant, you can increase the size of your system and re-create the optimal environment,” Ducci said. “If you’re a biologist and have identified the optimal conditions for cell growth, but need to produce in a larger amount, we can use these scaling parameters to make the reactor larger.”
Next up, the team plans to extend their research to other types of noncylindrical reactors and improving cell suspensions, to further bridge the gap between different types of bioreactors.
This article has been republished from materials provided by American Institute of Physics. Note: material may have been edited for length and content. For further information, please contact the cited source.
Weheliye, W. H., Cagney, N., Rodriguez, G., Micheletti, M., & Ducci, A. (2018). Mode decomposition and Lagrangian structures of the flow dynamics in orbitally shaken bioreactors. Physics of Fluids, 30(3), 033603. doi:10.1063/1.5016305
Testosterone Effective at Combating Cachexia in Cancer PatientsNews
Many cancer patients suffer from a loss of body mass known as cachexia. A new study shows that the hormone testosterone is effective at combatting cachexia in cancer patients and improving quality of life.READ MORE | <urn:uuid:4cbc8fba-8652-4e4c-a391-cc1d70e5cc7f> | 3.015625 | 763 | Truncated | Science & Tech. | 37.08304 | 95,557,333 |
Diversity and carbon stock assessment of trees and lianas in tropical dry evergreen forest on the Coromandel Coast of India
P. Vivek and N. Parthasarathy*
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Abstract: The diversity and carbon stock of all woody plants were investigated in ten tropical dry evergreen forest (TDEF) sites on the Coromandel Coast of India. All trees ≥ 10 cm girth at breast height and all lianas ≥ 1 cm diameter, measured at 1.3 m from the rooting point were enumerated. A total of 81 tree species (26.3±6.7 species ha-1) and 52 liana species (23.4±5.7 species ha-1) that belonged respectively to 34 and 28 families were inventoried from the ten study sites. The abundance of woody plants in the ten study sites totaled 18705 individuals (9466 trees and 9239 lianas) and the average tree density was 946.6±298.9 stems ha-1 and liana density was 923.9±403.3 stems ha-1. Trees contributed 61 % and 51 % respectively to the total woody species richness and abundance. The basal area of trees in the ten study sites ranged from 8.23 m2 ha-1 to 29.48 m2 ha-1 and that of lianas ranged from 0.2 m2 ha-1 to 1.76 m2 ha-1. The aboveground biomass (AGB) of trees totaled 3025.8 Mg and ranged from 96.9 Mg ha-1 to 576.4 Mg ha-1 across the ten sites. The liana aboveground biomass ranged from 2.24 Mg ha-1 to 42.13 Mg ha-1 and totaled 153.76 Mg in the ten sites. The woody plants in the present study sites stocked 1978.24 Mg Carbon and it ranged from 62.2 Mg C ha-1 to 365.4 Mg C ha-1. Trees accounted for a maximum share of 95 % and lianas contributed just 5 % to the total woody-plant carbon stock in the study sites. The extent of woody species diversity and estimated carbon stock of the TDEF sites, underlines the need for biological conservation of this unique forest type which are fast vanishing due to anthropogenic pressure.
Fig.: Map showing ten tropical dry evergreen forest sites distributed in Cuddalore, Pudukottai and Nagapattinam districts on the Coromandel Coast of India. | <urn:uuid:e81b73f0-23a6-48c6-827d-4b561b3b3d5e> | 2.640625 | 538 | Academic Writing | Science & Tech. | 84.784588 | 95,557,346 |
The study appears in the current issue of the Proceedings of the National Academy of Sciences, authored by James Hansen of NASA's Goddard Institute for Space Studies, N.Y. and colleagues from Columbia University, Sigma Space Partners, Inc., and the University of California at Santa Barbara (UCSB).
The study concludes that, because of a rapid warming trend over the past 30 years, the Earth is now reaching and passing through the warmest levels in the current interglacial period, which has lasted nearly 12,000 years. This warming is forcing a migration of plant and animal species toward the poles.
The study includes worldwide instrumental temperature measurements during the past century. These data reveal that the Earth has been warming at the remarkably rapid rate of approximately 0.2° Celsius (.36° Fahrenheit) per decade for the past 30 years. This observed warming is similar to the warming rate predicted in the 1980s in initial global climate model simulations with changing levels of greenhouse gases.
"This evidence implies that we are getting close to dangerous levels of human-made (anthropogenic) pollution," said Hansen. In recent decades, human-made greenhouse gases (GHGs) have become the dominant climate change factor.
The study notes that the world's warming is greatest at high latitudes of the Northern Hemisphere, and it is larger over land than over ocean areas. The enhanced warming at high latitudes is attributed to effects of ice and snow. As the Earth warms, snow and ice melt, uncovering darker surfaces that absorb more sunlight and increase warming, a process called a positive feedback. Warming is less over ocean than over land because of the great heat capacity of the deep-mixing ocean, which causes warming to occur more slowly there.
Hansen and his colleagues in New York collaborated with David Lea and Martin Medina-Elizade of UCSB to obtain comparisons of recent temperatures with the history of the Earth over the past million years. The California researchers obtained a record of tropical ocean surface temperatures from the magnesium content in the shells of microscopic sea surface animals, as recorded in ocean sediments.
One of the findings from this collaboration is that the Western Equatorial Pacific and Indian Oceans are now as warm as, or warmer than, at any prior time in the Holocene. The Holocene is the relatively warm period that has existed for almost 12,000 years, since the end of the last major ice age. The Western Pacific and Indian Oceans are important because, as these researchers show, temperature change there is indicative of global temperature change. Therefore, by inference, the world as a whole is now as warm as, or warmer than, at any time in the Holocene.
According to Lea, “The Western Pacific is important for another reason, too: it is a major source of heat for the world’s oceans and for the global atmosphere.”
In contrast to the Western Pacific, the researchers find that the Eastern Pacific Ocean has not shown an equal magnitude of warming. They explain the lesser warming in the East Pacific Ocean, near South America, as being due to the fact this region is kept cool by upwelling, rising of deeper colder water to shallower depths. The deep ocean layers have not yet been affected much by human-made warming.
Hansen and his colleagues suggest that the increased temperature difference between the Western and Eastern Pacific may boost the likelihood of strong El Ninos, such as those of 1983 and 1998. An El Nino is an event that typically occurs every several years when the warm surface waters in the West Pacific slosh eastward toward South America, in the process altering weather patterns around the world.
The most important result found by these researchers is that the warming in recent decades has brought global temperature to a level within about one degree Celsius (1.8° F) of the maximum temperature of the past million years. According to Hansen “That means that further global warming of 1 degree Celsius defines a critical level. If warming is kept less than that, effects of global warming may be relatively manageable. During the warmest interglacial periods the Earth was reasonably similar to today. But if further global warming reaches 2 or 3 degrees Celsius, we will likely see changes that make Earth a different planet than the one we know. The last time it was that warm was in the middle Pliocene, about three million years ago, when sea level was estimated to have been about 25 meters (80 feet) higher than today.”
Global warming is already beginning to have noticeable effects in nature. Plants and animals can survive only within certain climatic zones, so with the warming of recent decades many of them are beginning to migrate poleward. A study that appeared in Nature Magazine in 2003 found that 1700 plant, animal and insect species moved poleward at an average rate of 6 kilometers (about 4 miles) per decade in the last half of the 20th century.
That migration rate is not fast enough to keep up with the current rate of movement of a given temperature zone, which has reached about 40 kilometers (about 25 miles) per decade in the period 1975 to 2005. “Rapid movement of climatic zones is going to be another stress on wildlife” according to Hansen. “It adds to the stress of habitat loss due to human developments. If we do not slow down the rate of global warming, many species are likely to become extinct. In effect we are pushing them off the planet.”
Rob Gutro | EurekAlert!
New research calculates capacity of North American forests to sequester carbon
16.07.2018 | University of California - Santa Cruz
Scientists discover Earth's youngest banded iron formation in western China
12.07.2018 | University of Alberta
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
18.07.2018 | Life Sciences
18.07.2018 | Life Sciences
18.07.2018 | Information Technology | <urn:uuid:35bf08d6-3475-4382-833d-86af13268a93> | 4.28125 | 1,747 | Content Listing | Science & Tech. | 42.397653 | 95,557,349 |
This years Antarctic ozone hole is the second largest ever observed, according to scientists from NASA, the National Oceanic and Atmospheric Administration (NOAA), and the Naval Research Laboratory (NRL). The Antarctic ozone "hole" is defined as thinning of the ozone layer over the continent to levels significantly below pre-1979 levels. Ozone blocks harmful ultraviolet "B" rays. Loss of stratospheric ozone has been linked to skin cancer in humans and other adverse biological effects on plants and animals.
CALM COOL SKIES SPELL LOSSES
This year, colder temperatures and calmer winds allowed chemical reactions that break down ozone to occur at about the same rates as the past few years. However, last years unusually moderate Antarctic temperatures and highly variable upper atmospheric winds kept the ozone hole relatively small, about 40% smaller in area than the record sizes seen in 2000, 2001, and this year. In 2002, the hole also split into two parts for the first time since 1979, also due to unusual weather patterns. These comparisons pit the near-record size of this years hole against a) the small area of last years hole and b) the split shape from last year. Data from TOMS-EP.
The size of this years Antarctic ozone hole reached 10.9 million square miles on September 11, 2003, slightly larger than the North American continent, but smaller than the largest ever recorded, on September 10, 2000, when it covered 11.5 million square miles. Last year the ozone hole was smaller, covering 8.1 million square miles.
NASAs Earth Probe Total Ozone Mapping Spectrometer and the NOAA-16 Solar Backscatter Ultraviolet instrument provided ozone measurements from space. These data were coupled with data collected by NOAA’s Climate Monitoring and Diagnostics Laboratory (CMDL) from balloon-borne instruments, which measure the ozone hole’s vertical structure.
Rob Gutro | GSFC
In the ocean's twilight zone, tiny organisms may have giant effect on Earth's carbon cycle
19.07.2018 | Florida State University
New research calculates capacity of North American forests to sequester carbon
16.07.2018 | University of California - Santa Cruz
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:ee362da2-9a87-49d1-b382-b941490337e0> | 4.3125 | 1,025 | Content Listing | Science & Tech. | 42.259902 | 95,557,362 |
An international team led by an Edinburgh astronomer have discovered that by studying polarised light from black holes they can focus much more closely on what exactly is going on around them. The work is published this week in the monthly notices of the Royal Astronomical Society on November 11th.
Studying black holes at the centre of galaxies is difficult. A huge amount of material is falling on to the centre in an active black hole system, and this falling material is thought to power the black hole, but scientists still dont understand this powering mechanism. One critical reason is that these black holes are just too far away for astronomers to isolate the light from them - or more accurately, the light from the compact region where the black holes are actually producing their energy.
However, Kishimoto at the University of Edinburgh and the international team of Antonucci at UC Santa Barbara, Boisson at Paris Observatory, and Blaes also at UC Santa Barbara, have used the Keck I telescope in Hawaii and European Southern Observatorys Very Large Telescope in Chile, to do this isolation of the light. They have looked at a small part of the light emitted from black holes - light that has been scattered as it passes through the clouds very nearby. This scattered light can cleverly be picked up by looking through a polaroid filter just like the lens of polaroid sunglasses, which essentially blocks the unwanted light from elsewhere in the galaxy. The scattered light is polarised so the light waves all line up in the same direction and can pass through the Polaroid filter, but light from the surrounding area which is not polarised is excluded by the filter.
Julia Maddock | 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
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
20.07.2018 | Health and Medicine
19.07.2018 | Earth Sciences
19.07.2018 | Power and Electrical Engineering | <urn:uuid:a507eaa4-5503-466d-8705-646d2cf0a4c0> | 3.59375 | 969 | Content Listing | Science & Tech. | 40.881758 | 95,557,374 |
The next time someone whispers in your ear, think "cochlea."
The cochlea is the marvelous structure in the inner ear that is shaped like a snail shell and transforms sounds into the nerve impulses that your brain can process and interpret. You may remember learning about it in elementary school anatomy.
This critical hearing organ consists of a fluid-filled tube about a cubic centimeter (three hundredths of an ounce) in volume. For decades, hearing experts thought that its spiral shape was simply an efficient packing job and its shape had no effect on how it functions. But a recent study headed by Vanderbilt mathematician Daphne Manoussaki calls this conventional wisdom into question. She and her colleagues, Richard Chadwick and Emilios Dimitriadis of the National Institutes of Health, have created a mathematical model of the cochlea that finds the spiral shape acts to enhance the low frequency sounds that we use to communicate with one another. They published the results recently in the journal Physical Review Letters.
David F. Salisbury | EurekAlert!
Computer model predicts how fracturing metallic glass releases energy at the atomic level
20.07.2018 | American Institute of Physics
What happens when we heat the atomic lattice of a magnet all of a sudden?
18.07.2018 | Forschungsverbund Berlin
A new manufacturing technique uses a process similar to newspaper printing to form smoother and more flexible metals for making ultrafast electronic devices.
The low-cost process, developed by Purdue University researchers, combines tools already used in industry for manufacturing metals on a large scale, but uses...
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
20.07.2018 | Materials Sciences
20.07.2018 | Physics and Astronomy
20.07.2018 | Materials Sciences | <urn:uuid:afd7fd13-529b-4ea8-b478-a0b0bcf303fc> | 3.546875 | 793 | Content Listing | Science & Tech. | 39.269995 | 95,557,375 |
Controlling molecular properties through photoirradiation holds great promise for its potential for noninvasive and selective manipulation of matter. Photochromism has been observed for several different molecules, including green fluorescent proteins, and recently the discovery of a novel photoswitchable green fluorescent protein called Dronpa was reported. Dronpa displays reversible and highly efficient on/off photoswitching of its fluorescence emission, and reversible switching of immobilized single molecules of Dronpa with response times faster than 20 ms was demonstrated. In this Letter, we expand these observations to freely diffusing molecules by using fluorescence correlation spectroscopy with simultaneous excitation at 488 and 405 nm. By varying the intensity of irradiation at 405 nm, we demonstrate the reversible photoswitching of Dronpa under these conditions, and from the obtained autocorrelation functions we conclude that this photoswitching can occur within tens of microseconds. © 2006 by the Biophysical Society.
Mendeley saves you time finding and organizing research
Choose a citation style from the tabs below | <urn:uuid:f0669b17-41ee-4093-8766-6d96ebfd7a9c> | 2.546875 | 213 | Academic Writing | Science & Tech. | 1.37647 | 95,557,376 |
A new advancement in solar cells could enable solar power in areas plagued by frequent overcast skies. Scientists from the University of British Columbia (UBC) have developed a cheaper and sustainable method to build biogenic solar cell, using bacteria that converts light to energy and generates a current stronger than any previously recorded from a solar cell, while efficiently dimming light. The researchers believe the discovery could eventually lead to solar cells that are as efficient as the synthetic cells used in conventional solar panels. “Our solution to a uniquely B.C. problem is a significant step toward making solar energy more economical,” Vikramaditya Yadav, a professor in UBC's department of chemical and biological engineering who led the project, said. Solar cells convert light into electrical current for solar panels. Previously, scientists have attempted to build biogenic solar cells by extracting the natural dye that bacteria use for photosynthesis. … [Read more...] about Bacteria-Powered Solar Cells Prevail on Cloudy Days
New power solar
A NEW £7m solar farm is now operational, producing enough electricity to power one of the north's largest water treatment plants.NI Water has today drastically reduced its carbon footprint by the launch of the new solar farm on a 33 acre site on the eastern shore of Lough Neagh. The new 24,000 panel solar farm will power the Dunore Water Treatment Works (WTW) in south Antrim. and is expected to save over half a million pounds annually in energy costs for the company.As well as meeting the energy needs of the Dunore WTW, the project will also enable the company to contribute spare capacity to the grid.NI Water is Northern Ireland's biggest user of electricity and Dunore is its third largest site in terms of energy consumption accounting for 7 per cent of the company's annual usage.Speaking at the completion of the latest project, NI Water CEO, Sara Venning said the new solar farm is another step in reducing the company's carbon footprint.“As the largest user of electricity in … [Read more...] about New £7m solar farm powering one of the north’s largest water treatment plants.
SUNNYVALE, Calif.--(BUSINESS WIRE)--May 1, 2018--Alta Devices, the world-record holder for single junction solar cell efficiency, announces the launch of its fourth-generation solar cell technology (“Gen4”), which weighs significantly less than the previous generation technology (“Gen3”) and results in an improved power-to-weight ratio of 160 percent. This technology is critical for tomorrow’s unmanned aerial vehicles (UAVs), solar cars and other electric vehicles. It can be used to generate substantial power over small surfaces with minimal impact to vehicle design criteria.This press release features multimedia. View the full release here: https://www.businesswire.com/news/home/20180501005560/en/Alta Devices Gen4 solar cells can be used to power everything; UAVs, automobiles, sensors, and more (Photo: Business Wire)“Autonomy in the air and on the ground is becoming a reality,” said Jian Ding, Alta Devices CEO. “While there has been much … [Read more...] about Alta Devices Launches New Generation Solar Cell Designed to Empower Autonomy for UAVs and Other Vehicles
Spirit Island BUY NOWSpirit Island could be a Bizzaro-world sequel to The Settlers of Catan. Instead of colonizing a newfound landmass, you and your friends team up as the invaded isle's guardian spirits. You'll muster the native population, deploy your elemental powers, and work together to frighten, drive, and otherwise murder the invading settlers off your sacred land. Catan fights back, baby!Wonderfully complex but not excessively complicated, Spirit Island is the best cooperative game of the decade (yes, even better than Pandemic). As spirits, you'll spend your turns building influence on the game board, learning new powers, and picking which ones to use. Meanwhile, the game automates the unceasing advance of the settlers who explore, settle, and ravish new biomes in a set order. The game includes dozens of ways to modulate the difficulty, but even for the easiest modes require an almost preternatural cleverness; your team needs to know which battles to fight, and to discover the … [Read more...] about The 50 Best New Board Games
An interstellar object called 'Oumuamua has confounded astronomers ever since it passed through our solar system in October of last year. Scientists initially thought that the object — the first-ever visitor from another solar system spotted by Earth-based telescopes — was a comet. Later, they considered it an asteroid and even later described it as a possibly comet-like icy body with a rocky crust. Now, scientists have found that in addition to its confusing appearance, 'Oumuamua — an up to 1,300-foot-long (400 meters), cucumber-shaped object — likely has a rather dramatic history. [Danger! Falling Rocks: Meteorites and Asteroids (Infographic)] When astronomers from Queen's University Belfast in Northern Ireland observed the changes in the object's brightness, they found that it is not spinning regularly, like the majority of known asteroids and small bodies in the solar system do. Rather, it is chaotically tumbling. 'Oumuamua's erratic motion might be a … [Read more...] about Something Violent Happened to Our Solar System’s First Interstellar Visitor | <urn:uuid:bbfee148-9569-4329-b663-20fad0960f74> | 3.1875 | 1,147 | Content Listing | Science & Tech. | 41.565295 | 95,557,387 |
A quantum internet, a sophisticated work of fiction that kept security experts daydreaming because of the perfect secure communication it can provide, not only already exists but a U.S. government laboratory, the Los Alamos National Lab, has been running it for two years.
The basic idea here is that the act of measuring a quantum object, such as a photon, always changes it. So any attempt to eavesdrop on a quantum message cannot fail to leave telltale signs of snooping that the receiver can detect. That allows anybody to send a one-time pad over a quantum network which can then be used for secure communication using conventional classical communication.
That sets things up nicely for perfectly secure messaging known as quantum cryptography and this is actually a fairly straightforward technique for any half decent quantum optics lab. Indeed, a company called ID Quantique sells an off-the-shelf system that has begun to attract banks and other organisations interested in perfect security.
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|Somebody Needs to Build a New Facebook Stat| | <urn:uuid:b8474fcb-0449-45f0-8935-f55cfecf0f8d> | 2.625 | 421 | Content Listing | Science & Tech. | 39.303153 | 95,557,389 |
By: Dale Bass
It may look like a compass, but the solar installation at Thompson Rivers University is designed to do more.
Ultimately, said Michael Mehta, it could point the way to integrating charging strips in roadways that could charge electric vehicles as they are being driven.
For now, however, the solar compass outside the Arts and Education Building on campus has other purposes, said Mehta, a geography and environmental-studies professor at TRU.
First, it’s to demonstrate how solar can be commonplace and not relegated to large panels on tops of buildings or out in fields. It’s also designed to show solar projects can also look good.
Mehta entered the project into the university’s sustainability grant competition. Once approved, he opted to use the existing compass design at the building, but build into it more than five dozen one-foot by two-foot solar modules, each producing 80 watts of power that ultimately should see it generate enough power per year to run about 40 computers and printers.
Just prior to the official unveiling of the compass on Thursday, with the city experiencing its first significant snowstorm of the season, Mehta kept an eye on the installation to see how people reacted walking on it. He didn’t expect to see a flurry of falls, he said, because the only real difference people might feel walking on it is the modules have a slightly different friction level than the sidewalks surrounding them.
He likened it to walking on a sidewalk and encountering a painted line or a grate. There’s a different feel underfoot, but nothing too significant.
The compass has been in place and generating energy since July, so students are likely familiar with its underfoot feel, he said.
The solar walkway is a first in Canada. The university invested about $30,000 in the project, which Mehta and other researchers will continue to monitor.
The panels were donated to the university by Solar Earth Technologies. | <urn:uuid:391b6f26-3e99-4aa3-8450-ef7994e50c04> | 3 | 408 | News Article | Science & Tech. | 40.540657 | 95,557,391 |
July 7, 2014 – Environmental research conducted at the Vale Living With Lakes Centre of Laurentian University is the focus of an article published in the international research journal Nature Communications. Lead author Dr. Andrew Tanentzap of University of Cambridge, U.K., carried out studies on acquatic food chains in Daisy Lake, in Sudbury, Ontario. The findings of the research point to important linkages between healthy forests in boreal ecosystems and the viability of fish stocks in those freshwater lakes.
The study found that young yellow perch in Daisy Lake were better-nourished in areas where forest debris washed into the lake, supplementing the aquatic food chain. In parts of the lake with less surrounding vegetation, the fish had fewer microscopic zooplankton to feed upon and were smaller in size.
“We found fish with almost 70% of their biomass made from carbon that came from trees and leaves, instead of aquatic food chain sources,” said Dr. Tanentzap. “Essentially, the young fish in lake areas with scant forest cover were smaller, and thus less likely to breed and survive. Those in areas with abundant forest cover were definitely a more robust population.”
A Banting Fellow at the Living With Lakes Centre during much of his research, Dr. Tanentzap and his colleagues from the University of Cambridge will return to Sudbury this fall for a 3-year continuation of the project.
“We are delighted to see Andrew’s work highlighted in Nature Communications,” said Dr. John Gunn, Director of the Living with Lakes Centre and Canada Research Chair for Stressed Aquatic Systems. “Sudbury’s unique landscape is a globally significant research laboratory, and the Cambridge project shows how our recovered waterways create real benefits in the downstream receiving waters.”
The Living With Lakes Centre is a centre of excellence for the study of stressed and recovering freshwater ecosystems, and has been the site of numerous research projects in environmental and natural resource management studies.
Dr. Tanentzap said that while the team’s research focussed on boreal regions, the findings are likely to bear out globally, in all regions that have experienced forest loss. “The degradation and destruction of forest lands have a direct impact on aquatic food chains. It matters because freshwater fish make up more than 6% of humans’ protein supplies and are their primary source of omega-3 fatty acids,” he said. | <urn:uuid:21054664-f572-4320-a803-74b712e9c575> | 3.203125 | 505 | News (Org.) | Science & Tech. | 39.501564 | 95,557,415 |
For the first time precarious rocks have been analysed in the epicentral area of the AD 1356 Basle earthquake in northern Switzerland. Several cliff sites in flat-lying, thickly bedded Upper Jurassic coral limestones in the Jura Mountains were investigated. Seven blocks are regarded as precarious with respect to earthquake strong ground motions. The age of these precarious rocks could not be determined directly as for instance by radiometric dating methods; however, based on slope degradation processes it can be concluded that the formation of these blocks predates the AD 1356 Basle earthquake. The acceleration required to topple a precarious rock from its pedestal is estimated using geometrical data for individual block sections and earthquake strong-motion records from stations on rock sites in the European Strong-Motion Database as input data for the computer program ROCKING V1.0 from the Seismological Laboratory, University of Nevada, Reno. The calculations indicate that toppling of a precarious rock largely depends on earthquake strength but also on the frequency spectrum of the signal. Although most investigated precarious rocks are surprisingly stable for ground motions similar to those expected to have occurred during the AD 1356 Basle earthquake, at least two blocks are clearly precariously balanced, with peak toppling accelerations lower than 0.3 g. Possible reasons why these blocks did not topple during the AD 1356 Basle earthquake include incomplete separation from their base, sliding of precarious rocks, their size, lower than assumed ground accelerations and/or duration of shaking
To submit an update or takedown request for this paper, please submit an Update/Correction/Removal Request. | <urn:uuid:c5a824e3-6fe6-4a6c-849f-33394773285c> | 2.703125 | 322 | Academic Writing | Science & Tech. | 20.773091 | 95,557,423 |
In one of the first studies looking at the effect of ocean acidification on shellfish, Stephanie Talmage, PhD candidate, and Professor Chris Gobler showed that the larval stages of these shellfish species are extremely sensitive to enhanced levels of carbon dioxide in seawater.
Their work will be published in the November issue of the journal Limnology and Oceanography and is now online at http://www.aslo.org/lo/toc/vol_54/issue_6/index.html.
“In recent decades, we have seen our oceans threatened by overfishing, harmful algal blooms, and warming. Our findings suggest ocean acidification poses an equally serious risk to our ocean resources,” said Gobler.
During the past century the oceans absorbed nearly half of atmospheric carbon dioxide derived from human activities such as burning fossil fuels. As the ocean absorbs carbon dioxide it becomes more acidic and has a lower concentration of carbonate, which shell-making organisms use to produce their calcium carbonate structures, such as the shells of shellfish.
In lab experiments, Talmage and Gobler examined the growth and survivorship of larvae from three species of commercially and ecologically valuable shellfish. They raised the larvae in containers bubbled with different levels of carbon dioxide in the range of concentrations that are projected to occur in the oceans during the 21st century and beyond.
Under carbon dioxide concentrations estimated to occur later this century, clam and scallop larvae showed a more than 50% decline in survival. These larvae were also smaller and took longer to develop into the juvenile stage. Oysters also grew more slowly at this level of carbon dioxide, but their survival was only diminished at carbon dioxide levels expected next century.
“The longer time spent in the larval stage is frightening on several levels,” said Talmage. “Shellfish larvae are free swimming. The more time they spend in the water column, the greater their risk of being eaten by a predator. A small change in the timing of the larval development could have a large effect on the number of larvae that survive to the juvenile stage and could dramatically alter the composition of the entire population.”
Although levels of carbon dioxide in marine environments will continue to rise during this century, organisms in some coastal zones are already exposed to high levels of carbon dioxide due to high levels of productivity and carbon input from sources on land.
“This could be an additional reason we see declines in local stocks of shellfish throughout history,” said Talmage. “We’ve blamed shellfish declines on brown tide, overfishing, and local low-oxygen events. However it's likely that ocean acidification also contributes to shellfish declines.”
Talmage and Gobler hope their work might help improve the success rate of shellfish restoration projects.
“On Long Island there are many aquaculturists who restock local waters by growing shellfish indoors at the youngest stages and then release them in local estuaries,” said Talmage. “We might be able to advise them on ideal carbon dioxide conditions for growth while larvae are in their facilities, and offer suggestions on release times so that conditions in the local marine environment provide the young shellfish the best shot at survival.”
About the School of Marine and Atmospheric Sciences at Stony Brook University
The School of Marine and Atmospheric Sciences (SoMAS) is the State University of New York's center for marine and atmospheric research, education, and public service. With more than 85 faculty and staff and more than 500 students engaged in interdisciplinary research and education, SoMAS is at the forefront of advancing knowledge and discovering and resolving environmental challenges affecting the oceans and atmosphere on both regional and global scales.
Leslie Taylor | Newswise Science News
Further reports about: > ACIDification > Atmospheric > Atmospheric Sciences > Marine and Atmospheric Sciences > Marine science > Pacific Ocean > Science TV > Shellfish larvae > SoMAS > algal bloom > carbon dioxide > marine environment > ocean acidification > scallop larvae > shell-making organisms > shellfish
Upcycling of PET Bottles: New Ideas for Resource Cycles in Germany
25.06.2018 | Fraunhofer-Institut für Betriebsfestigkeit und Systemzuverlässigkeit LBF
Dry landscapes can increase disease transmission
20.06.2018 | Forschungsverbund Berlin e.V.
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
16.07.2018 | Life Sciences
16.07.2018 | Earth Sciences
16.07.2018 | Physics and Astronomy | <urn:uuid:bb9fc58f-3935-4dec-aeaf-80255d7c6d23> | 3.546875 | 1,499 | Content Listing | Science & Tech. | 33.314831 | 95,557,425 |
Is liquid hydrogen safer than liquid methane?
This paper compares the physical and combustion-related properties of the liquid state of hydrogen (LH2) and methane (LCH4). This type of comparison is important for studying the safe use of these chemicals as aircraft fuels, although it cannot yield definite conclusions because the actual effect on safety depends on the conditions of the accident.
KeywordsOxygen Index Burning Velocity Fire Technology Liquid Hydrogen Normal Boiling Point
Unable to display preview. Download preview PDF.
- 1.Dean, J. W., “A Tabulation of the Thermodynamic Properties of Normal Hydrogen,” National Bureau of Standards, NBS Technical Note 120, Boulder, Colorado (November 1969).Google Scholar
- 2.Hord, J., “Is Hydrogen Safe?” National Bureau of Standards, NBS Technical Note 690, Boulder, Colorado (October 1976).Google Scholar
- 3.Carson, L. K., Davis, G. W., Versaw, E. F., Cunnington F. R., Jr., and Daniels, E. J., “Study of Methane Fuel for Subsonic Transport Aircraft” NASA Contractor Report 159320, Lockheed-California Co., Burbank, California (September 1980).Google Scholar | <urn:uuid:e6911fda-b62c-493d-9f47-b231f9075948> | 2.96875 | 268 | Truncated | Science & Tech. | 51.270533 | 95,557,437 |
In this program we are going to make an excel sheet and
set the fonts of text values, set its size. We can also set the name of the
The packages we need to import are java.io.*,java.util.* ,org.apache.poi.hssf.usermodel.HSSFSheet,org.apache.poi. hssf. usermodel. HSSFCellStyle, org.apache.poi.usermodel.HSSFRow, org.apache.poi.usermodel.HSSFCell , org.apache.poi.hssf.usermodel. HSSFWorkbook and org.apache.poi.hssf.usermodel.HSSFFont.
extends java.lang.Object and is used to represent a font used in workbook.
This also provides various methods to set various font properties on
In this example we are using following key points:
This method is used to set the height of the text.
This method is used to set the font name.
This method is used the to set text as Italic.
This method is used to set strikeout on text.
This method is used to set font on cell style sheet.
The code of the program is given below:
The output of the program is given below: | <urn:uuid:e12d5d9d-5251-4780-824d-315fdbc02711> | 3.375 | 284 | Documentation | Software Dev. | 74.98069 | 95,557,466 |
The Arctic is home to a growing number of whales and ships, and to populations of sub-Arctic whales that are expanding their territory into newly ice-free Arctic waters.
A study of the narrow passage of the Bering Strait uses underwater microphones to track the whales by their sounds. Three years of recordings reveal more detections of both Arctic and sub-Arctic whales traveling through the narrow choke point.
A fin whale is shown breaching the water's surface.
Credit: Kate Stafford, UW
Kate Stafford, an oceanographer with the University of Washington's Applied Physics Laboratory, will present the results Feb. 26 at the Ocean Sciences meeting in Honolulu. The recordings show Arctic beluga and bowhead whales migrating seasonally through the region from the Arctic south to spend winter in the Bering Sea. They also detect large numbers of sub-Arctic humpback, fin and killer whales traveling north through the Bering Strait to feed in the biologically rich Chukchi Sea.
"It's not particularly surprising to those of us who work up in the Arctic," Stafford said. "The Arctic seas are changing. We are seeing and hearing more species, farther north, more often. And that's a trend that is going to continue."
Stafford placed microphones below the water's surface and recorded in summer and early winter from 2009 to 2012 as part of a U.S.-Russian scientific collaboration. Melodious humpback whale songs showed up regularly on recordings into late fall. Fin and killer whales, which are southern species that seldom travel into Arctic waters, were heard into early November.
"These animals are expanding their range," Stafford said. "They're taking advantage of regions in seasons that they may not have previously."
The recordings also picked up ships using the ice-free summers to travel through two international shipping lanes. This poses an increased risk of collisions between whales and ships, and of noise pollution.
"Marine mammals rely primarily on sound to navigate, to find food and to find mates. Sound is their modality," Stafford said. "If we increase the ambient sound level, it has the potential to reduce the communication range of cetaceans and all marine mammals."
The Bering Strait is famous as a land bridge that prehistoric humans used to travel from Russia to North America. Today, the waterway is 58 miles wide and maximum 160 feet deep, with about one-third of its span in U.S. waters and the rest in Russia. The two coasts are quite different, Stafford said, which makes the international collaboration essential to understanding the full environment.
A recent paper by Stafford and other scientists includes visual sightings of killer whales, a quieter southern-dwelling whale, just north of the strait in the southern Chukchi Sea. Killer whales are now seen fairly regularly in this area, which is being considered for oil and gas exploration.
"The Arctic areas are changing," Stafford said. "They are becoming more friendly to sub-Arctic species, and we don't know how that will impact Arctic whales. Will they be competitors for food? Will they be competitors for habitat? Will they be competitors for acoustic space, for instance these humpbacks yapping all the time in the same frequency band that bowheads use to communicate? We just don't know."
Stafford supports the idea of slowing ship speeds in the Bering Strait, reducing motor noise and the chance of ship strikes.
Another suggestion to protect whales builds on tagging work showing that bowhead whales tend to travel up the U.S. side on the way north in the spring and on the Russian side on their way back in the fall. The proposal suggests that ships follow the American coast in the fall and the Russian coast in the spring to reduce interactions between ships and whales.
Still to be explored is whether the increased whale travel through the region is due to rising whale populations, expanded ranges, or both. Logbooks from Soviet whaling ships in the mid-to-late 20th century report sub-Arctic whales in the region, but none were seen from about 1980 to 2010.
"The question is, are these whale populations recovering and so they're reoccupying former habitat, or are they actually invading the Arctic because they can, because there is less seasonal sea ice?" Stafford said.
Collaborators on the research are Janet Clarke at Leidos Inc. and Sue Moore at the National Oceanic and Atmospheric Administration. The research was funded by the U.S. National Science Foundation and the National Oceanic and Atmospheric Administration.
For more information, contact Stafford at 206-685-8617 or firstname.lastname@example.org.
Stafford will speak in Session #102 at the Ocean Sciences meeting in Honolulu on Wednesday, Feb. 26 at 2:45 p.m. in room 316A.
Hannah Hickey | EurekAlert!
Innovative genetic tests for children with developmental disorders and epilepsy
11.07.2018 | Christian-Albrechts-Universität zu Kiel
Oxygen loss in the coastal Baltic Sea is “unprecedentedly severe”
05.07.2018 | European Geosciences Union
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
19.07.2018 | Materials Sciences
19.07.2018 | Earth Sciences
19.07.2018 | Life Sciences | <urn:uuid:7e2811af-cc6a-43a0-ab85-0c911400c041> | 3.96875 | 1,642 | Content Listing | Science & Tech. | 48.791267 | 95,557,472 |
A split-ring resonator (SRR) is an artificially produced structure common to metamaterials. Their purpose is to produce the desired magnetic susceptibility (magnetic response) in various types of metamaterials up to 200 terahertz. These media create the necessary strong magnetic coupling to an applied electromagnetic field, not otherwise available in conventional materials. For example, an effect such as negative permeability is produced with a periodic array of split ring resonators.
A single cell SRR has a pair of enclosed loops with splits in them at opposite ends. The loops are made of nonmagnetic metal like copper and have a small gap between them. The loops can be concentric, or square, and gapped as needed. A magnetic flux penetrating the metal rings will induce rotating currents in the rings, which produce their own flux to enhance or oppose the incident field (depending on the SRRs resonant properties). This field pattern is dipolar. The small gaps between the rings produces large capacitance values which lower the resonating frequency. Hence the dimensions of the structure are small compared to the resonant wavelength. This results in low radiative losses, and very high quality factors.
Split ring resonators (SRRs) consist of a pair of concentric metallic rings, etched on a dielectric substrate, with slits etched on opposite sides. SRRs can produce an effect of being electrically smaller when responding to an oscillating electromagnetic field. These resonators have been used for the synthesis of left handed and negative refractive index media, where the necessary value of the negative effective permeability is due to the presence of the SRRs. When an array of electrically small SRRs is excited by means of a time varying magnetic field, the structure behaves as an effective medium with negative effective permeability in a narrow band above SRR resonance. SRRs have also been coupled to planar transmission lines, for the synthesis of transmission line metamaterials.
The split ring resonator and the metamaterial itself are composite materials. Each SRR has an individual tailored response to the electromagnetic field. However, the periodic construction of many SRR cells is such that the electromagnetic wave interacts as if these were homogeneous materials. This is similar to how light actually interacts with everyday materials; materials such as glass or lenses are made of atoms, an averaging or macroscopic effect is produced.
The SRR is designed to mimic the magnetic response of atoms, only on a much larger scale. Also, as part of periodic composite structure these are designed to have a stronger magnetic coupling than is found in nature. The larger scale allows for more control over the magnetic response, while each unit is smaller than the radiated electromagnetic wave.
SRRs are much more active than ferromagnetic materials found in nature. The pronounced magnetic response in such lightweight materials demonstrates an advantage over heavier, naturally occurring materials. Each unit can be designed to have its own magnetic response. The response can be enhanced or lessened as desired. In addition, the overall effect reduces power requirements.
There are a variety of split-ring resonators and periodic structures: rod-split-rings, nested split-rings, single split rings, deformed split-rings, spiral split-rings, and extended S-structures. The variations of split ring resonators have achieved different results, including smaller and higher frequency structures. The research which involves some of these types are discussed throughout the article.
To date (December 2009) the capability for desired results in the visible spectrum has not been achieved. However, in 2005 it was noted that, physically, a nested circular split-ring resonator must have an inner radii of 30 to 40 nanometers for success in the mid-range of the visible spectrum. Microfabrication and nanofabrication techniques may utilize direct laser beam writing or electron beam lithography depending on the desired resolution.
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Split-ring resonators (SRR) are one of the most common elements used to fabricate metamaterials. Split-ring resonators are non-magnetic materials The first ones were usually fabricated from circuit board material to create metamaterials.
Looking at the image directly to the right, it can be seen that at first a single SRR looked like an object with a two square perimeters, and each perimeter with small segment removed, which results in squared "C" shapes, on fiberglass, printed circuit board material. In this type of configuration it is actually two concentric bands of non-magnetic conductor material. There is one gap in each band placed 180° relative to each other. The gap in each band gives it the distinctive "C" shape, rather than a totally circular or square shape. Then multiple cells of this double band configuration are fabricated onto circuit board material by an etching technique and lined with copper wire strip arrays are added. After processing, the boards are cut and assembled into an interlocking unit. It is constructed into a periodic array with a large number of SRRs.
There are now a number of different configurations that use the SRR nomenclature.
A periodic array of SRRs was used for the first demonstration of a negative index of refraction. For this demonstration, square shaped SRRs, with the lined wire configurations, were fabricated into a periodic, arrayed, cell structure. This is the substance of the metamaterial. Then a metamaterial prism was cut from this material. The prism experiment demonstrated a negative index of refraction for the first time in the year 2000; the paper about the demonstration was submitted to the journal Science on January 8, 2001, accepted on February 22, 2001 and published on April 6, 2001.
Just before this prism experiment, Pendry et al. was able to demonstrate that a three-dimensional array of intersecting thin wires could be used to create negative values of ε. In a later demonstration, a periodic array of copper split-ring resonators could produce an effective negative μ. In 2000 Smith et al. were the first to successfully combine the two arrays and produce a LHM which had negative values of ε and μ for a band of frequencies in the GHz range.
SRRs were first used to fabricate left-handed metamaterials for the microwave range, and several years later for the terahertz range. By 2007, experimental demonstration of this structure at microwave frequencies has been achieved by many groups. In addition, SRRs have been used for research in acoustic metamaterials. The arrayed SRRs and wires of the first Left-handed metamaterial were melded into alternating layers. This concept and methodology was then applied to (dielectric) materials with optical resonances producing negative effective permittivity for certain frequency intervals resulting in "photonic bandgap frequencies". Another analysis showed Left Handed Material to be fabricated from inhomogeneous constituents, which yet results in a macroscopically homogeneous material. SRRs had been used to focus a signal from a point source, increasing the transmission distance for near field waves. Furthermore, another analysis showed SRRs with a negative index of refraction capable of high-frequency magnetic response, which created an artificial magnetic device composed of non-magnetic materials (dielectric circuit board).
The resonance phenomena that occurs in this system is essential to achieving the desired effects.
SRRs also exhibit resonant electric response in addition to their resonant magnetic response. The response, when combined with an array of identical wires is averaged over the whole composite structure which results in effective values, including the refractive index. The original logic behind SRRs specifically, and metamaterials generally was to create a structure, which imitates an arrayed atomic structure only on a much larger scale.
Several types of SRR
In research based in metamaterials, and specifically negative refractive index, there are different types of split-ring resonators. Of the examples mentioned below most all of them have a gap in each ring. In other words, with a double ring structure, each ring has a gap.
There is the 1-D Split-Ring Structure with two square rings, one inside the other. One set of cited "unit cell" dimensions would be an outer square of 2.62 mm and an inner square of 0.25 mm. 1-D structures such as this are easier to fabricate compared with constructing a rigid 2-D structure.
The Symmetrical-Ring Structure is another classic example. Described by the nomenclature these are two rectangular square D type configurations, exactly the same size, lying flat, side by side, in the unit cell. Also these are not concentric. One set of cited dimensions are 2 mm on the shorter side, and 3.12 mm on the longer side. The gaps in each ring face each other, in the unit cell.
The Omega Structure, as the nomenclature describes, has an Ω-shaped ring structure. There are two of these, standing vertical, side by side, instead of lying flat, in the unit cell. In 2005 these were considered to be a new type of metamaterial. One set of cited dimensions are annular parameters of R = 1.4 mm and r = 1 mm, and the straight edge is 3.33 mm.
Another new metamaterial in 2005 was a coupled “S” shaped structure. There are two vertical "S" shaped structures, side by side, in a unit cell. There is no gap as in the ring structure, however there is a space between the top and middle parts of the S and space between the middle part and bottom part of the S. Furthermore, it still has the properties of having an electric plasma frequency and a magnetic resonant frequency.
Other types of split-ring resonators are the spiral resonator with 8 loops. broadside coupled split-ring resonator (BC-SRR). Two-layer multi spiral resonator (TL-MSR), the broad-side coupled spiral resonator with four turns, the complementary split ring resonator , the open split-ring resonator (OSRR) , and the open complementary split-ring resonator (OCSRR) . Transmission line configurations include SRR-based CRLH (composite right-left-handed) transmission line and its equivalent compliment.
Split ring resonator research
On May 1, 2000 conducting wires were placed symmetrically within each cell of a periodic split-ring resonator array which achieved negative propagation of electromagnetic waves in the microwave region. The concept was and still is used to build interacting elements smaller than the applied electromagnetic radiation. In addition, the spacing between, referred to as the lattice constant, is also smaller than the applied radiation.
Additionally, the splits in the ring allow the SRR unit to achieve resonance at wavelengths much larger than the diameter of the ring. The unit is designed to generate a large capacitance, lower the resonant frequency, and concentrate the electric field. Combining units creates a design as a periodic medium. Furthermore, the multiple unit structure has strong magnetic coupling with low radiative losses. Research has also covered variations in magnetic resonances for different SRR configurations. Research has continued into terahertz radiations with SRRs Other related work fashioned metamaterial configurations with non-SRR structures. These can be constructed with materials such as periodic metallic crosses, or an ever-widening concentric ring structures known as Swiss rolls. Permeability for only the red wavelength at 780 nm has been analyzed and along with other related work
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- History of metamaterials
- Quantum metamaterials
- Metamaterial cloaking
- Photonic metamaterials
- Metamaterial antennas
- Nonlinear metamaterials
- Photonic crystal
- Seismic metamaterials
- Acoustic metamaterials
- Metamaterial absorber
- Plasmonic metamaterials
- Terahertz metamaterials
- Tunable metamaterials
- Transformation optics
- Theories of cloaking
- Academic journals
- Metamaterials books
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- Google scholar List of Papers by JB Pendry
- Imperial College, Department of Physics, Condensed Matter Theory Group
- Personal Profile of John Pendry at Imperial college
- Video: John Pendry lecture: The science of invisibility April 2009, SlowTV
- Shepard, K. W. et al. Split-ring resonator for the Argonne Superconducting Heavy Ion Booster. IEEE Transactions on Nuclear Science, VoL. NS-24, N0.3, JUN 1977.
- Split Ring Resonator Calculator: Online tool to calculate the LC equivalent circuit and resonant frequency of SRR and CSRR topologies.
Ates, Damla; Cakmak, Atilla Ozgur; Colak, Evrim; Zhao, Rongkuo; Soukoulis, C. M.; Ozbay, Ekmel (2010). "Transmission enhancement through deep subwavelength apertures using connected split ring resonators" (Free PDF download). Optics Express. 18 (4): 3952–66. Bibcode:2010OExpr..18.3952A. doi:10.1364/OE.18.003952. PMID 20389408. | <urn:uuid:474b4519-a867-4079-af0d-b22fc8b9f88b> | 3.78125 | 6,425 | Knowledge Article | Science & Tech. | 66.067003 | 95,557,508 |
NASA’s Juno spacecraft, currently orbiting Jupiter, routinely captures stunning views of the giant planet’s turbulent atmosphere, providing a treasure-trove of data for researchers and citizen-scientists like Seán Doran, who carries out sophisticated processing of raw imagery from the spacecraft’s JunoCam public-outreach camera. This view captures Jupiter’s Great Red Spot during Juno’s seventh low-altitude pass.
Now that planet Saturn is effectively lost in the dusk twilight for UK-based observers, you may be wondering what has happened to the other four bright naked-eye planets. Far from disappearing, they have just transferred to the morning sky. From 8—11 October, the waning crescent Moon acts as a guide to Venus, Mars, Jupiter then Mercury in the eastern dawn sky.
In recent nights, observers in the UK and Western Europe have seen the International Space Station (ISS) as a bright naked-eye ‘star’ moving slowly across the sky from west to east. On Thursday, 9 June, London is favoured for some close approaches of the ISS to the Moon, Jupiter and Saturn. If you see the Station, spare a thought for Tim Peake and the Expedition 47 crew on board! | <urn:uuid:b5276ce8-1f75-4b76-85ef-f4dd8659f70d> | 3.296875 | 254 | News Article | Science & Tech. | 43.989864 | 95,557,533 |
What are the three types of heat transfer? Provide a description of each and indicate its key formulas.© BrainMass Inc. brainmass.com July 16, 2018, 12:08 pm ad1c9bdddf
The three types of heat transfer are conduction, convection, and radiation.
Conduction is heat passing through a material. Thermal energy can be understood as excited atoms whose vibration motion increases with temperature. The excited atoms collide with the neighboring atoms passing on thermal energy which is gained by it neighbor. This is conductive heat transfer. Also included is thermal energy transfer through diffusion of the atoms. An everyday example can be seen in an egg on a pan. The hot burner of the stove transfers its heat to the pan. The heat moves through the pan material to reach the egg. The heat is then transferred to the egg. This is heat transfer by conduction. It happens through materials and when two objects touch each other.
The main ...
This solution of over 500 words provides an overview of the different types of heat transfer. The basic fundamental equation for each is provided. Examples of where these types of heat transfer occur are also provided. Original text is provided in docx and pdf format. | <urn:uuid:054a825b-96ca-46b6-bc6e-306e4b8bb65e> | 3.953125 | 247 | Truncated | Science & Tech. | 60.969167 | 95,557,534 |
A team of researchers led by Walter Robert Binns of Washington University in St. Louis has detected traces of 60Fe in cosmic rays flying through space, revealing that ashes from a nearby supernova continue to rain down on Earth up to this day.
After proving the existence of Einstein's gravitational waves, researchers has once again discovered something that is not expected-light bursting from the collision of two black holes.
After being involved in an "unusual tugging" with an undiscovered planet, NASA's Cassini Spacecraft in Saturn is once again making its way in the headlines.
A recent discovery by scientists at the Technical University of Munich (TUM) found traces of iron isotopes in samples from the moon, similar to those found on our ocean floor, leading them to believe that it came from the same supernova explosion.
It pays to clean one's basement once in a while. A 1917 astronomical glass plate was unearthed from the collections of Carnegie Observatories in Pasadena, California revealed the first-ever evidence of exoplanetary system.
Stephen Hawking amazed the community once again. Together with esteemed colleagues, he recently launched a $100-million space exploration project called Breakthrough Starshot, which aims to reach the nearest star system, Alpha Centauri, in a span of 20 years.
NASA is preparing for an ambitious journey to Mars in 2030. The monumental space exploration does not only concern NASA, but it has also ignited the drive for space scientists, engineers and entrepreneurs to develop space technology dedicated to developing habitations on Mars. One of them is a startup called RedWorks who is developing a 3-D printing system to build homes on the Red planet.
Super-Earths may want to back off a bit. A new study revealed a new class of planets outside our own solar system with atmospheres stripped away by their host stars.
Researchers from the University of Cape Town and University of Western Cape have accidentally discovered a mysterious alignment of super massive black holes in a distant universe.
Mars will soon begin its retrograde motion on Saturday, April 16. During its retrograde motion, It will seem like Mars is going on reverse.
A recent video released by NASA shows that astronomers have found an icy "spider" on Pluto's surface.
Ground control to Major Sam! Sam the dog is on the loose -- not just in any dog park, but after his trip to the edge of space.
Mayday, mayday! We have trouble in space. NASA's exoplanet hunter, Kepler, which is stationed 75 million miles away from home, malfunctions. In a routine scheduled contact, the Kepler entered into Emergency Mode, alarming NASA's engineers.
BEAM me up, Scotty! NASA recently partnered with the private company Bigelow Aerospace to develop the Bigelow Expandable Activity Module, also known as BEAM. Launched into space this Friday, it's an inflatable inhabitation module that can help provide astronauts with "safe and sustainable space living quarters, workspaces and laboratories."
Monster black holes can usually be found at the core of very large galaxies and is rarely seen in the center of a galaxy in a sparsely populated area in the universe. The is the reason why researchers at NASA were shocked when they uncovered a massive black hole weighing about 17 billion suns in the center of NGC 1600. | <urn:uuid:522994e3-19fc-4254-9519-b4b8b65baaed> | 2.65625 | 680 | Content Listing | Science & Tech. | 37.708933 | 95,557,543 |
The fungi Aspergillus niger (top left), Penicillium simplicissimum (top right) and Penicillium chrysogenum (bottom) can recycle cobalt and lithium from rechargeable batteries. Credit: Aldo Lobos Although rechargeable batteries in smartphones, cars and tablets can be charged again and again, they don’t last forever. Old batteries often wind up in landfills or incinerators, potentially harming the environment. And valuable materials remain locked inside. Now, a team of researchers is turning to naturally occurring fungi to drive an environmentally friendly recycling process to extract cobalt and lithium from tons of waste batteries. The researchers will present their work today at the 252nd National Meeting & Exposition of the American Chemical Society (ACS). ACS, the world’s largest scientific society, is holding the meeting here through Thursday. It features more than 9,000 presentations on a wide range of science topics.
”The idea first came from a student who had experience extracting some metals from waste slag left over from smelting operations,” says Jeffrey A. Cunningham, Ph.D., the project’s team leader. ”We were watching the huge growth in smartphones and all the other products with rechargeable batteries, so we shifted our focus. The demand for lithium is rising rapidly, and it is not sustainable to keep mining new lithium resources,” he adds.
Although a global problem, the U.S. leads the way as the largest generator of electronic waste. It is unclear how many electronic products are recycled. Most likely, many head to a landfill to slowly break down in the environment or go to an incinerator to be burned, generating potentially toxic air emissions.
While other methods exist to separate lithium, cobalt and other metals, they require high temperatures and harsh chemicals. Cunningham’s team is developing an environmentally safe way to do this with organisms found in nature—fungi in this case—and putting them in an environment where they can do their work. ”Fungi are a very cheap source of labor,” he points out.
To drive the process, Cunningham and Valerie Harwood, Ph.D., both at the University of South Florida, are using three strains of fungi—Aspergillus niger, Penicillium simplicissimum and Penicillium chrysogenum. ”We selected these strains of fungi because they have been observed to be effective at extracting metals from other types of waste products,” Cunningham says. ”We reasoned that the extraction mechanisms should be similar, and, if they are, these fungi could probably work to extract lithium and cobalt from spent batteries.”
The team first dismantles the batteries and pulverizes the cathodes. Then, they expose the remaining pulp to the fungus. ”Fungi naturally generate organic acids, and the acids work to leach out the metals,” Cunningham explains. ”Through the interaction of the fungus, acid and pulverized cathode, we can extract the valuable cobalt and lithium. We are aiming to recover nearly all of the original material.”
Results so far show that using oxalic acid and citric acid, two of the organic acids generated by the fungi, up to 85 percent of the lithium and up to 48 percent of the cobalt from the cathodes of spent batteries were extracted. Gluconic acid, however, was not effective for extracting either metal.
The cobalt and lithium remain in a liquid acidic medium after fungal exposure, Cunningham notes. Now his focus is on how to get the two elements out of that liquid.
”We have ideas about how to remove cobalt and lithium from the acid, but at this point, they remain ideas,” he says. ”However, figuring out the initial extraction with fungi was a big step forward.”
Other researchers are also using fungi to extract metals from electronic scrap, but Cunningham believes his team is the only one studying fungal bioleaching for spent rechargeable batteries.
Cunningham, Harwood and graduate student Aldo Lobos are now exploring different fungal strains, the acids they produce and the acids’ efficiencies at extracting metals in different environments.
Explore further:Electric-car battery materials could harm key soil bacteria
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Image courtesy of mBioRICHLAND, Wash. – While relentless bright light brings many forms of cyanobacteria to their knees—figuratively, of course—Synechococcus sp. PCC 7002 does the opposite, thriving and growing at a rate that far outpaces most of its peers. That makes the organism, commonly called a form of blue-green algae, an attractive target for scientists and engineers trying to create better, less expensive biofuels or develop tools for churning out custom chemicals.
Now researchers have figured out why Synechococcus 7002 is so robust. The organism triples in size to accommodate a rapid expansion of the cellular machinery it uses to build proteins, the workhorses of cells. The organism flourishes under intense light by using the energy to keep growing.
The findings by scientists at the U.S. Department of Energy's Pacific Northwest National Laboratory, in collaboration with scientists from several other institutions, appeared July 26 in the online journal mBio.
Of sunlight and Synechococcus
Cyanobacteria capture the Sun's energy and use it to create food for themselves, all while drawing in carbon dioxide and giving off oxygen. The single-celled organisms have been on Earth for billions of years and play a critical role in Earth's climate. Scientists are trying to take advantage of these natural processes to create new forms of energy and sustainable bioproducts.
"These organisms are the major pathway for capturing solar energy and carbon dioxide on our planet," said PNNL scientist Alexander Beliaev, one of two corresponding authors.
When light comes in too fast and too intensely for most cyanobacteria, they slow their growth, using their resources instead to repair damaged cells.
Photo courtesy of Pacific Northwest National LaboratoryBut Synechococcus sp. PCC 7002 is adept at using the extra light, doing chemistry on the fly and putting the extra energy to good use—toward rapid growth. The organism typically doubles in size in less than two hours, compared to other species which typically double between seven to 12 hours.
That may not sound like much. But if you start with a one-foot by one-foot plot of blue-green algae, after 48 hours the standard organism would cover the floor of a small office, while the fast-growth one would cover more than 600 football fields. That's an attractive difference for scientists trying to grow the organism as a source of fuel. The greater productivity means that more fuel and more chemical products could be produced more quickly compared to other systems.
"Everyone's question is: How can we make affordable fuels and chemicals faster? It's a critical choke point for renewable biofuel processes," said Hans Bernstein, also a corresponding author. Fuels made of biological materials—such as ethanol—currently make up a small slice of fuels used today, largely because they are more expensive than traditional fuels. The new research is one step toward making a wider range of biofuels less costly and more attractive.
Expanding the cellular machinery
The team led by Beliaev and Bernstein set out to understand the capability of Synechococcus sp. PCC 7002 for fast growth. They drew upon the resources of EMSL, the Environmental Molecular Sciences Laboratory—a Department of Energy user facility—to ferret out the molecular signals that underpin the organism's ability to stay productive even under bright light, using EMSL's capabilities to determine which genes were active.
Under bright light conditions where other cyanobacteria normally slow down, the team saw no hint of slowdown in the organism. Instead, the scientists demonstrated that the organism has the wherewithal to expand very rapidly, building molecular machinery quickly to convert light energy and carbon dioxide into new growth.
The scientists showed that the organism activates more of the genetic signals involved in creating the raw materials involved in building proteins in the cell. The activity of genes involved in building proteins, harvesting light, converting sunlight into food and taking up carbon dioxide all increased markedly. To accommodate the increased activity, the cells triple in size.
It's like a factory with the capability of expanding its assembly lines instantaneously to accommodate an increased flow of raw materials coming into the manufacturing area. If the electrons that provide energy aren't used immediately, they can get in the way and gunk up operations, but if they're put to good use, more of the desired product rolls off the lines quickly and efficiently.
"This organism responds to very high light levels by fixing carbon dioxide and upregulating machinery to make biomass," said Bernstein. "It's building proteins as fast as it can for rapid growth, and that requires additional space."
The team included scientists from PNNL, the Colorado School of Mines, Penn State, Montana State University, and Purdue. The work was funded by the Department of Energy Office of Science.
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Temperatures at the North Pole could be up to 20 degrees higher than average this Christmas Eve, in what scientists say is a record-breaking heatwave, a media report said on Saturday. Friederike Otto, a senior researcher at Oxford’s Environmental Change Institute told BBC News that in pre-industrial times “a heatwave like this would have been extremely rare – we would expect it to occur about every 1,000 years”.
Temperatures are forecast to peak on Christmas Eve around the North Pole – at near-freezing. The warm air from the North Atlantic is forecast to flow all the way to the North Pole via Spitsbergen, giving rise to clouds that prevent heat from escaping.
Otto told the BBC News, the reduction in sea ice is contributing to this “feedback loop”.
Forecasting models show that there is about a 2% chance of a heatwave event occurring every year. Thorsten Markus, chief of NASA’s Cryospheric Sciences Laboratory, said the heatwave was “very, very unusual”. | <urn:uuid:59ef8c71-7e99-408d-bd08-62d6ff003989> | 3.5625 | 225 | News Article | Science & Tech. | 43.258659 | 95,557,581 |
On Friday, August 3, the low pressure area known as "System 90L" was being watched for development. It was located south of the Cape Verde Islands off the African coast. By the early evening (Eastern Daylight Time) it quickly organized. System 90L strengthened and became Tropical Storm Florence in the eastern Atlantic. Over August 4 and 5 Florence traveled west and weakened back to a tropical depression by August 6.
The AIRS instrument that flies on NASA's Aqua satellite captured these infrared images of Florence on Aug. 4-5. The AIRS image from Aug. 4 showed a larger spiraled storm. By Aug. 5 when dry air started interacting with the system the area of stronger thunderstorms had diminished and the storm had a tight, small area of strong, high, cold cloud tops of thunderstorms around the center of circulation.
Credit: NASA/JPL, Ed Olsen
After Florence became a tropical storm she ran into dry air and Saharan dust, according to the National Hurricane Center (NHC). At 5 a.m. EDT on Monday, August 6, the NHC noted "the cyclone has been devoid of deep convection for about six hours as dry air has become well embedded in the circulation."
Forecasters at the National Hurricane Center expect Florence to track west across the Atlantic and south of Bermuda. On her western track, Florence is expected to degenerate to a remnant low within the next couple of days, because wind shear will increase from the west and batter the storm. Florence became a post-tropical storm on August 6 at 11 a.m. EDT as its winds dropped to 35 mph (55 kmh). It was located near latitude 16.4 north and longitude 40.2 west. Florence is expected to weaken further over the next couple of days.
Rob Gutro | EurekAlert!
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NSF-supported researchers to present new results on hurricanes and other extreme events
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For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
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Last month I had the chance to hold a replica of the upper part of a human airway—the windpipe plus the first two bronchi. It had been made from collagen, the biological cement that holds our bodies together. It was slippery and hollow, with the consistency of undercooked pasta.
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The structure had emerged from a refrigerator-size 3-D printer in Manchester, New Hampshire, at an outpost of United Therapeutics, a company that earns more than a billion dollars a year selling drugs to treat lung ailments.
One day, the company says, it plans to use a printer like this one to manufacture human lungs in “unlimited quantities” and overcome the severe shortage of donor organs.
Bioprinting tissue isn’t a new idea. 3-D printers can make human skin, even retinas. Yet the method, so far, has been limited to tissues that are very small or very thin and lack blood vessels.
United instead is developing a printer that it believes will be able, within a few years, to manufacture a solid, rubbery outline of a lung in exquisite detail, including all 23 descending branches of the airway, the gas-exchanging alveoli, and a delicate network of capillaries.
A lung made from collagen won’t help anyone: it’s to a real lung what a rubber chicken is to an actual hen. So United is also developing ways to impregnate the matrix with human cells so they’ll attach and burrow into it, bringing it alive.
“We are trying to build the little stick houses for cells to live in,” says Derek Morris, a project leader in United’s organ manufacturing group.
The 3-D-printing project is the latest in a series of high-wire engineering efforts launched by United’s CEO, Martine Rothblatt, a onetime aerospace entrepreneur (she was the founding CEO of Sirius Satellite Radio) who changed careers in the 1990s after her daughter developed a rare lung disease.
In creating United, Rothblatt parlayed an abandoned drug she picked up for $25,000 into a company that made her the highest-paid CEO in the biopharmaceutical industry last year—when she also set a speed record in an electric helicopter. Rothblatt says she expects electric drones to someday whisk organs from her factory to wherever they are needed.
United has already made some risky organ bets. One of its subsidiaries, Revivicor, supplies surgeons with hearts, kidneys, and lungs from genetically engineered pigs (these have been used in baboons, so far). Another, Lung Bioengineering, refurbishes lungs from human donors by pumping warm solution into them. About 250 people have already received lungs that would otherwise have been designated medical waste.
Don’t expect fully manufactured organs soon. United, in its company projections, predicts it won’t happen for another 12 years. Rothblatt acknowledges that the printed structure I saw is just a start. “It’s only two branches and no cells,” she says.
Even so, United’s effort to print entire organs, which got under way last year, may be the industry’s largest. It hired a South Carolina company, 3D Systems, to build the printer and is paying another company, 3Scan, to slice up lungs and create detailed maps of their interior. It has job ads out for roles such as “Mathematician—Human Organ Design.”
United’s organ manufacturing group is located in the same complex of former textile mills as BioFabUSA, an $80 million Defense Department tissue-printing initiative. Dean Kamen, the well-known inventor who leads BioFabUSA, says meetings with Rothblatt were what led him to apply to the government to host the institute. “I saw miracles she’s playing with and the frustration of the equipment she is using to do it,” he says. To Kamen, biologists are hindered by what he calls “19th-century technology” of flasks and beakers.
The collagen printer 3D Systems is using now operates according to a method called stereolithography. A UV laser flickers through a shallow pool of collagen doped with photosensitive molecules. Wherever the laser lingers, the collagen cures and becomes solid. Gradually, the object being printed is lowered and new layers are added.
The printer can currently lay down collagen at a resolution of around 20 micrometers, according to United. Printing the anatomical details of a lung, however, will require features less than a micrometer in size.
“When you see the complexity of the lung, what nature does from conception to birth, there is no way to machine that or mold it. 3-D printing is the only way we have to create that geometry,” says Pedro Mendoza, director of bioprinting at 3DSystems.
Mendoza says 3D Systems plans to import techniques from the semiconductor industry—such as masks, mirrors, and more powerful lasers—to improve the printer’s resolution. Speed is also an issue. The structure I saw took 12 hours to print. A complete, detailed lung scaffold would take a year to build with the same printer.
Some bioprinted tissues are close to finding medical uses. A team in Spain has been printing skin it thinks could be used on burn patients. Yet all the tissues made today are paper thin. They have to be, because they lack blood vessels. Any bigger and a tissue would die from the inside out.
While some researchers have printed prototypes of living blood vessels, these efforts remain incipient. So far, no one has claimed a $300,000 prize offered by NASA to the first scientist able to print living tissue one centimeter thick. A pair of human lungs is much more substantial, weighing about three pounds.
Some companies say it’s still premature to talk about printing entire organs. “We all think it’s going to be possible at some point in the future. Where we differ is how long it will take,” says Sharon Presnell, chief scientist of Organovo, a California company that has been printing thin, elastic sheets of liver. “Can you get something that size with a vasculature, and can it take physiological pressure? Most of us are trying to walk before we run.”
Not United, though. It says the problem with other efforts is that they use extrusion methods, squeezing cells and proteins through fine needles. Luis Alvarez, the bioengineer who heads United's organ manufacturing group, likens printing cells to “pushing water balloons through a straw.” He says, “Your printing resolution is limited by the size of the cell.”
Instead, United’s plan is to print a lung scaffold first and then infuse it with human cells, a process called recellularization.
There is early evidence that a collagen matrix can be turned back into a functioning lung. This year, in an experiment partly financed by United, Harvard University experimental surgeon Harald Ott reported that he’d pumped billions of human cells (from umbilical cords and diced lungs) into a pig lung stripped of its own cells. When Ott’s team reconnected it to a pig’s circulation, the resulting organ showed rudimentary function, although the experiment lasted only an hour.
“You do get blood through the system, and you do get gas exchange,” says Finn Hawkins, a stem-cell biologist at Boston University, who is not involved in United’s project. “That is remarkable. But it’s a long way to transplantable organs.”
Hawkins says that Ott’s organs lacked important cell types, like the wavy cilia that remove phlegm. What’s more, it remains unclear how to obtain human cells in the quantities needed to supply a future organ factory. There aren’t enough human lungs from deceased donors to meet the demand.
United says it plans to use stem cells to manufacture the needed tissue in its labs, but that's no easy task either.
“I think the bioprinting may be the least problematic part of it,” Hawkins says. “As soon as you mention anything larger than a mouse, I would say it’s hard to make that quantity of cells.”
If organs could be manufactured in large numbers, it wouldn’t only solve the organ shortage. It could eventually reshape human life span. What about getting a new heart or lungs at 80?
To get there, United will have to pull off not one but several technological moonshots. Yet Alvarez says United is anticipating that its various technology projects—the 3-D-printed scaffold, the recellularization technique, and its effort to manufacture lung tissue from stem cells—will all intersect sometime in the future.
“By the time we get to printing the finest part of the lung,” he says, “we’ll know how to recellularize it.”
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SMEAR I - Värriö
The Värriö Subarctic Research Station and Forestry Field Station for Measuring Ecosystem-Atmosphere Relationship (SMEAR I, established in 1991) are located at the Arctic-alpine timberline in Värriö; strict nature reserve, Finnish Lapland (67oN, 29oE, 400 m a.s.l.). The area has a clear subarctic character (Hari and Mäkelä 2003; Kolari et al. 2007; Dengel et al. 2013) and the SMEAR I station is surrounded by a homogenous, 10 m tall Scots pine (Pinus sylvestris L.) forest. The main emphasis at SMEAR I is on interactions between forest and atmosphere, air quality and aerosols. Another aim of the station is to study the possible effects of air pollution on forest growth.
In 2012, an eddy-covariance (EC) flux measurements system was installed to study the carbon dioxide and water vapour exchange between the atmosphere and forest at ecosystem level (Figure 1). In 2013-2105, another setup was employed to study exchanges within the sub canopy space. First results show the forest to act as a clear sink for carbon dioxide with a high proportion being absorbed by the canopy but also by the understorey vegetation itself (Dengel et al. in prep.). Furthermore, automated chambers are measuring CO2 fluxes of pine shoots. While the EC and shoot chambers are recording throughout the year, additional automated soil chambers are recording ground CO2 fluxes during snow free periods.
SMEAR II - Hyytiälä
Ivan Mammarella, Kukka-Maaria Erkkilä, Üllar Rannik, Pasi Kolari, Tiia Grönholm, Olli Peltola, Timo Vesala
The measurements of energy and matter exchange between forest ecosystem and the atmosphere are carried out since 1996 at our Forestry Field Station for Measuring Ecosystem-Atmosphere Relationship (SMEAR II) located in Hyytiälä;, southern Finland (Figure 2). The measurements cover, among others, flux monitoring of CO2, H2O, CH4, N2O, O3, CO, VOCs (volatile organic compounds) and , which is tested as a proxy for photosynthetic carbon uptake. The fluxes are determined applying micrometeorological techniques (including gradient and eddy-covariance methods), automatic and manual chambers for soil, woody-tissue and shoot components, and soil gradient method. SMEAR II forms a unique facility for soil-tree-atmosphere continuous measurements that have been used in several international projects and during field courses and summer schools. As an example Figure 2 shows 12 years of CO2 exchange measurements at SMEAR II.
- Vesala et al. (2010) show that increasing autumn temperature enhances carbon efflux from the Hyytiälä Scots Pine forest, because respiration is strongly temperature dependent and it dominates over photosynthesis especially during late autumn when radiation levels are low. The long-term eddy-covariance dataset from SMEAR II was used in the study.
- Launiainen (2010) analysed twelve-years of eddy-covariance measurements to assess the seasonal and inter-annual variability of surface conductance and energy partitioning, whereas Ilvesniemi et al. (2010) studied the water balance of SMEAR II.
- In Rannik et al. (2009) size-integrated aerosol particle fluxes ranging from 10 nm to 1 μm were analysed for the diurnal, seasonal and annual variation using seven years of eddy-covariance measurements. They observed that the normalised deposition rate was higher in winter than in summer and even in spring period when frequent nucleation events occur and particle concentrations are dominated by small particles.
- Analysis of the functional dependence of particle deposition on driving environmental variables, particle size and possible other factors was analyzed by Mammarella et al. (2011), who found that the seasonal differences in deposition velocities are driven primarily by differences in particle size distribution. The higher winter-time deposition velocities were explained mainly by prevailing bi-modal distributions dominated by larger sizes.
- The recent paper by Rannik et al. (2012) focused on ozone deposition characteristics and partitioning into stomatal and non-stomatal fractions, using ten years of canopy-level ozone fluxes measured at SMEAR II.
Prof. John Grace University of Edinburgh
Prof. Jaana Bäck, Department of Forest Sciences, UHEL
Prof. Eero Nikinmaa, Department of Forest Sciences UHEL
Prof. Pertti Hari, Department of Forest Sciences UHEL
Dr. Mari Pihlatie, Department of Forest Sciences UHEL
Finnish Meteorological Institute
Figure 1: SMEAR I station tower. Photo: Sigrid Dengel.
Figure 2: Scenery from the SMEAR II site. Photo: Juho Aalto.
Figure 3: The weekly running means of net ecosystem exchange (NEE), photosynthesis (GPP) and ecosystem respiration (Reco) derived from our EC measurements from 2001 to 2012. For details of the carbon balance and its variability at the site see Kolari et al. (2009).
Dengel S, Siivola E, Vesala T (in prep.) On the complexity of measuring CO2 exchange of a northern subarctic Pinus Sylvestris L. forest in a complex terrain environment.
Dengel S, Grace J, Aakala T, Hari P, Newberry SL, Mizunuma T (2013) Spectral characteristics of pine needles at the limit of tree growth in subarctic Finland. Plant Ecology and Diversity 6:31-44. 10.1080/17550874.2012.754512
Hari P and Mäkelä A (2003) Annual pattern of photosynthesis in Scots pine in the boreal zone. Tree Physiol. 23:145-155.
Ilvesniemi H, Pumpanen J, Duursma R, Hari P, Keronen P, Kolari P, Kulmala M, Mammarella I, Nikinmaa E, Rannik Ü, Pohja T, Siivola E, Vesala T (2010) Water balance of a boreal Scots pine forest. Boreal Environ.Res. 15:375-396.
Kolari P, Lappalainen HK, Hanninen H, Hari P (2007) Relationship between temperature and the seasonal course of photosynthesis in Scots pine at northern timberline and in southern boreal zone. Tellus Series B-Chemical and Physical Meteorology 59:542-552. 10.1111/j.1600-0889.2007.00262.x
Kolari P, Kulmala L, Pumpanen J, Launiainen S, Ilvesniem H, Hari P, Nikinmaa E (2009) CO2 exchange and component CO2 fluxes of a boreal Scots pine forest. Boreal Environ.Res. 14:761-783.
Launiainen S (2010) Seasonal and inter-annual variability of energy exchange above a boreal Scots pine forest. Biosci. 7:1-20.
Mammarella I, Rannik U, Aalto P, Keronen P, Vesala T, Kulmala M (2011) Long-term aerosol particle flux observations. part II: Particle size statistics and deposition velocities. Atmos.Environ. 45:3794-3805. 10.1016/j.atmosenv.2011.04.022
Rannik Ü, Mammarella I, Aalto P, Keronen P, Vesala T, Kulmala M (2009) Long-term aerosol particle flux observations part I: Uncertainties and time-average statistics. Atmos.Environ. 43:3431-3439. 10.1016/j.atmosenv.2009.02.049
Rannik Ü, Altimir N, Mammarella I, Back J, Rinne J, Ruuskanen TM, Hari P, Vesala T, Kulmala M (2012) Ozone deposition into a boreal forest over a decade of observations: Evaluating deposition partitioning and driving variables. Atmospheric Chemistry and Physics 12:12165-12182. 10.5194/acp-12-12165-2012
Suni T, Rinne J, Reissell A, Altimir N, Keronen P, Rannik Ü, Dal Maso M, Kulmala M, Vesala T (2003) Long-term measurements of surface fluxes above a Scots pine forest in Hyytiälä, southern Finland, 1996-2001. Boreal Environ.Res. 8:287-301.
Vesala T, Launiainen S, Kolari P, Pumpanen J, Sevanto S, Hari P, Nikinmaa E, Kaski P, Mannila H, Ukkonen E, Piao SL, Ciais P (2010) Autumn temperature and carbon balance of a boreal Scots pine forest in southern Finland. Biogeosciences 7:163-176. | <urn:uuid:5e2b853f-6fd5-4e99-9df9-e7dedc9d786e> | 2.796875 | 1,991 | Knowledge Article | Science & Tech. | 49.034223 | 95,557,608 |
Mass spectrometers, one of the principal instruments for investigating chemical composition, operate by separating ions according to their mass/charge ratio by transmitting them through a magnetic and electrical field. The ions are initially created from molecules through a destructive process such as collision or laser irradiation and are evaluated after separation by an integrated detector.
The initial concept of mass spectrometry (MS) was ignited in the late 1890s, came to realization during the 20th century, and continues to evolve in the 21st century. The key milestones in the development of mass spectrometry are described below.
In 1921, the instrument that we now consider to be the first mass spectrometer (although it was then known as the ‘parabola spectrograph’) was constructed by J.J. Thomson. Thomson was the renowned British physicist who had some years earlier discovered the electron. Within the span of a few years, MS had become an established method for the separation of ions on the basis of their mass, although there was to be little significant development of the technique until the 1940s.
It was during the 1940s that MS began to move away from its academic origins to find use in more practical applications such as nuclear isotope enrichment and the study of the composition of petroleum.
In 1941, John Hipple designed the first portable mass spectrometer which was marketed by Westinghouse Electric. However, this model did not seem to catch the imagination of scientists, and was not a commercial success.
In 1943, the Consolidated Engineering Corporation (CEC) became the first company to achieve market success in the MS field, initially selling the CEC Model 21-101 mass spectrometer to the Atlantic Refining Corp. (Philadelphia, PA).
In 1946, the first time-of-flight (TOF) mass analyzer was developed by W. Stephens of Pennsylvania. TOF MS involves acceleration of ions through an electric field of known strength, which confers the same kinetic energy to all ions of equal charge. By measuring the time taken for a particle to reach the detector, the mass/charge ratio of particles can be calculated.
In 1948, the first mass spectrometer to use electron ionization (EI), the MS-2, was launched by Vickers in Manchester, England.
Also in 1948, the first ion cyclotron mass spectrometer, known as the Omegatron, was developed at the University of Minnesota. This spectrometer incorporated a dual inlet with a changeover valve for rapid sample switching.
During the early 1950s, the mass spectrometer was still extremely restricted in terms of its resolution limits. However, the instruments developed during this time may be considered the forerunners of today’s popular and ubiquitous benchtop models.
In 1953, Wolfgang Paul and Helmut Steinwedel initiated development of the quadrupole mass analyzer (and quadrupole ion trap). In such a device, ions are separated by use of a quadrupolar electrical field consisting of both direct current and radiofrequency components. Quadrupole instruments are currently very popular, with sales exceeding the total of all other types of mass spectrometer.
In 1956, Roland Gohlke and Fred McLafferty initiated the trend of coupling the mass spectrometer to other techniques by developing gas chromatography-mass spectrometry (GC-MS). Model 12-101 using GC-MS with a TOF mass spectrometer was developed by the Bendix Aviation Corporation and allowed mixtures to be analyzed without prior time-consuming separation.
Also in 1956, MS was first used to identify an organic compound by breaking down the molecule to form positive, negative and neutral fragments.
1960 saw the first use of the quadrupole mass spectrometer as a residual gas analyzer.
In 1964, W.M. Brubaker, P. Michael Uthe, and Robert Finnigan at EAI developed the first commercially available quadrupole mass spectrometer residual gas analyzer.
In 1965, the first pre-packaged magnetic sector incorporating a helium enrichment jet separator was developed by R. Ryhage of the Karolinska Institute and sold by LKB instruments.
In 1967, the first magnetic double-focusing GC-MS, the PerkinElmer Model 270, was introduced.
In 1968, the technique of electrospray ionization (ESI) at atmospheric pressure was investigated by Malcolm Dole and colleagues. This advance was important to the biological future of MS, although the technique would not be routinely used for two more decades.
During the 1970s, a number of important modifications to MS were developed, including Fourier-transform, secondary ionization, plasma desorption, laser desorption, thermal desorption, spark source, and glow discharge MS.
In 1974, Fourier-transform ion cyclotron resonance was introduced.
In 1976, Hewlett-Packard (HP) introduced the world’s first integrated, digital benchtop GC-MS system, the 5992. The 5992 also featured the world’s first true hyperbolic chromium-molybdenum alloy (Cr-Mo) quadrupole mass filter.
In 1982, Bruker Spectrospin in Switzerland began successfully installing the first Fouriertransform ion cyclotron resonance (FT-ICR) mass spectrometry systems, drawing on Bruker’s existing expertise in NMR and superconducting magnet technology.
In 1983, the first commercial ion-trap system was introduced by Finnigan MAT (San Jose, CA), originally intended as a GC detector. In this instrument, a scanning radio frequency causes ions of increasing mass-to-charge ratio to become successively unstable. Today, ion trap instruments are common in GC detectors, LC-MS detectors and standalone mass spectrometers.
In 1985, the technique known as matrixassisted laser desorption/ionization (MALDI) was developed by Koichi Tanaka of Shimadzu Corp.
In 1987, PerkinElmer SCIEX introduced the ELAN 500, the first ICP-MS system with platinum cones and an inert sample introduction system.
Also in 1987, Finnigan (later acquired by Thermo in 1990) launched the MAT 90 series of mass spectrometers—the first mass spectrometers on the market completely controlled by computers.
In 1988, the first commercial MALDI-TOF MS instrument, the LAMS- 50K, was launched by Shimadzu. MALDI rapidly became an important technique for analyzing biological samples, and was being used in protein structure studies by the 1990s.
Also during 1988, John B. Fenn published two articles relating to an electrospray technique that revolutionized mass spectrometry. These articles showed that the release of ions could be achieved by spraying a sample using an electrical field so that charged droplets are formed. As the water gradually evaporates from these droplets, freely hovering “stark naked” protein molecules remain. The method came to be called electrospray ionization (ESI).
Finally in 1988, HP introduced the 5971 MSD, the world’s first mass spectrometer to employ a true hyperbolic glass quadrupole.
In 1990, PerkinElmer launched the first turbomolecular-pumped ICP-MS instrument (the ELAN 5000).
In 1992, low-level peptide analysis using MS techniques became possible.
Also in 1992, Shimadzu Corp. launched the Kompact MALDI Series, enabling analyses of a wide range of applications including peptides, proteins, sugars, multiplex fats, nucleotides, pharmaceutical products and metabolites.
By 1993, limited oligonucleotide sequencing had become possible, driven in part by the demands of the Human Genome Project.
By 1996, MS was starting to be linked to HPLC instruments, and MS studies of viruses were beginning.
In 1997, Shimadzu Corp. launched the LCMS-QP8000 with ESI and Atmospheric Pressure Chemical Ionization interfaces.
In 2002, the Nobel Prize in Chemistry was given to three pioneers of techniques for the identification and structural analyses of biological macromolecules. The recipients included Koichi Tanaka (Shimadzu Corp.) for his development of MALDI and John B. Fenn, who was recognized for the development of ESI.
Also in 2002, Shimadzu Corp. announced and launched the laser ionization quadrupole ion trap time-of-flight mass spectrometer AX IMA-QIT.
In 2005, the technique known as Direct Analysis in Real Time (DART) was patented. DART is based on the atmospheric pressure interactions of long-lived electronic excited-state atoms or vibronic excited-state molecules with the sample and atmospheric gases.
In 2006, Shimadzu Corp. launched AXIMA-TOF2TM, the next generation in MALDI CID MS-MS, a TOF-TOF mass spectrometer with high-energy MS-MS.
Also in 2006, Waters Corporation introduced the SYNAPT High-Definition MS (HDMS) system at the American Society of Mass Spectrometry annual meeting in Seattle. The HDMS system analyzes ions by their size, shape and charge, in addition to mass.
Finally in 2006, Agilent introduced its innovative GeneSpring MS software to facilitate biomarker discovery from mass spectrometry data.
In 2008, Waters Corp. launched the SYNAPT MS system; a next-generation, quadrupole acceleration, time-of-flight (QA-TOF) mass spectrometry platform, designed to generate high quality, comprehensive data from complex biological samples.
Also in 2008, Agilent introduced the first mainstream mass spectrometer to break the femtogram-detection barrier.
In 2009, Thermo Fisher Scientific Inc. launched the LTQ Velos, the industry’s fastest and most-sensitive ion trap mass spectrometer, increasing both scan speed and resolution.
In 2010, Bruker obtained the first in vitro diagnostic CE mark for its MALDI-TOF-based microbial identification workflow solution, the IVD MALDI Biotyper. This system is pioneering the advancement of mass spectrometry in clinical diagnostics.
In 2010, Waters Corp. introduced two new mass spectrometers for its Xevo MS platform (the Xevo TQ-S and Xevo G2 QTof) that offer an unequalled combination of separation power with the highest levels of sensitivity for compound identification, quantification and screening.
Future of MS
MS technology is still evolving to meet the latest demands of biotechnology. Innovations include tandem expansions, multiple connections to HPLC and the development of newer, portable systems. It is predicted that MS will remain the keystone of modern chemical analysis, as well as the ultimate chromatography detector.
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In the two cavity klystron, the electron beam is injected into a resonant cavity. The electron beam, accelerated by a positive potential, is constrained to travel through a cylindrical drift tube in a straight path by an axial magnetic field. While passing through the first cavity, the electron beam is velocity modulated by the weak RF signal. In the moving frame of the electron beam, the velocity modulation is equivalent to a plasma oscillation. Plasma oscillations are rapid oscillations of the electron density in conducting media such as plasmas or metals. The frequency only depends weakly on the wavelength. So in a quarter of one period of the plasma frequency, the velocity modulation is converted to density modulation, i.e. bunches of electrons. As the bunched electrons enter the second cavity they induce standing waves at the same frequency as the input signal. The signal induced in the second cavity is much stronger than that in the first. | <urn:uuid:cd94826e-c0b6-45b7-9a84-e01813412e71> | 3.5 | 192 | Academic Writing | Science & Tech. | 36.977428 | 95,557,634 |
Artificial Intelligence has been an endless source of fascination for decades, prompting moral and philosophical debate on what it means to sentient or self-aware, and what rights should come with those states of mind. We see potential quandaries fictionalized in popular TV and literature, from Data the loveable android in Star Trek: The Next Generation to Samantha the Operating System in the hit movie ‘Her’. What is frightening to consider is exactly how close we, in fact, are to sharing a world with these seemingly futuristic A.I.s. Could a self-learning and emotion-feeling robot make an appearance in our lifetime?
As evidenced by the recent artificial intelligence advances listed below, it is a possibility we would do well to consider.
Imagine a technology that could tell what you’re feeling just from looking at your face. The newly developed ‘Emotient’ software records your facial expressions at 30 frames per second, then translates its findings into an interpretation of your emotions. Perhaps this doesn’t sound too scary, considering we could simply conceal our emotions through a neutral facial expression, thereby fooling ‘Emotient’. This is harder than you might think, argues Emotient creator Ken Denman. The technology picks up on the smallest of ‘micro-expressions’ that even humans tend to miss, therefore seeing straight through a poker face and proving accurate in over 90% of its readings. This highly advanced development in what could technically be used as lie detection is somewhat disturbing. Will interrogations of the future be carried out by intimidating robots?
Next on the list of artificial intelligence advances is something equally disturbing. In Carnegie Mellon University in Pittsburgh, a group of roboticists have helped a robot learn how to grip, not through programming, but through letting the robot teach itself. The team gave the robot arms which it could extend, rotate and use to grasp objects. The robot knew that the objective was to pick up an object (an act it would detect through the sensors in its clasps). The robot was then left to its own devices for hours, clasping up to 50,000 times as it tested different ways to achieve the objective. Every time it failed or succeeded in picking something up, the robot would become better at predicting which approaches were more likely to work. Without any human intervention, the robot has now developed past the stage of clumsily gripping nothing but air for hours on end, to successfully grasping things over 70% of the time. It may seem like a small step, but how long until a robot not only knows how to learn but also starts deciding what they want to learn?
The experiment recently conducted at the New York Polytechnic Institute has demonstrated an incredible milestone for robotics, and moving us into dangerous territory as a result. In what might be one of the creepiest artificial intelligence advances ever, a robot has passed a self-awareness test it was initially thought only humans could pass. Three robots were used in the experiment, all of which were programmed to know that two of them had been given a “dumbing pill” which would make them mute. When the professor then asked, “which one of you hasn’t received the dumbing pill?”, only one robot would have the ability to answer “I don’t know”. This is exactly what the speech-capable robot did – he responded that he did not know which of them had not been given the dumbing pill. Upon hearing its own reply, however, the robot deduced that it must be the one who avoided the dumbing pill. The robot, in other words, identified itself as a separate entity from the other robots and was able to make a logical conclusion based on this.
A mind-controlled prosthetic limb has given a young, paralyzed man the opportunity to regain some normality back into his life. The fingers of his robot hands have been fitted with sensors that, when touched, induce electric signals that mimic touch sensations. Blindfolded, the man can determine which finger is being touched close to 100% of the time. Incredibly, the man can also control the prosthetic arm through thought, thanks to the electrodes that have been inserted into his sensory and motor cortexes. The technology is clearly being used for a fantastic purpose and should give us high hopes as to what more we can achieve within the field of prosthetic body parts.
The implications this has for future robots is far from clear, however. Will robots ever feel touch, rather than just sense it? Could robots ever feel actual pleasure or pain from being touched, using a variation of the aforementioned technology? Even before we start worrying about robots, we should perhaps consider the idea of fitting a human with a robotic arm that is stronger than a biological arm. Should we ever allow a human to be fitted with a robotic arm that can extend further than the human arm can, or which could double up as a useful tool – transforming into a pen, or a knife, when needed? Should we fear the potential danger of this human/robotic hybrid, or welcome it as a logical next step in mankind’s advancement?
As exciting and potentially beneficial artificial intelligence advances could be to the human race, even some experts in the field agree there is plenty of reason to be concerned. Stephen Hawking believes A.I. will end humanity if we are not careful, whilst Elon Musk compares A.I. to ‘summoning the devil’. “Once the machines are sentient and super intelligent… they’ll be able to make even smarter machines. And even smarter. And smarter. And suddenly, humans won’t be so necessary anymore,” writes Drake Baer in Business Insider. It seems the dystopia of science fiction might just be around the corner after all.
If you want to learn more about the recent artificial intelligence advances, consider reading the related article “Five Creepiest Advances in Artificial Intelligence.”
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