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River and lake waters were separated into four fractions to study the removal of nitrogen and carbon organic matter using chitosan (CH) and aluminium sulphate (AS). The fractions were very hydrophobic acid, slightly hydrophobic acid, charged hydrophilic acid and neutral hydrophilic. The results showed that the whole and fractionated water from both sources have a markedly hydrophobic character. However, lake water had a lower NOM concentration than river water. The ratio of dissolved organic carbon and dissolved organic nitrogen (DOC/DON) and dissolved inorganic nitrogen to total dissolved nitrogen (DIN/TDN) were higher in the hydrophobic fraction from both sources. Similarly DOC, colour and ultraviolet absorbance at 254 nm (UV254) also presented higher values in the same fraction. Chitosan achieved the better results in the removal of NOM from Boaco water, whole and fractionated, whereas aluminium sulphate achieved better removal from Juigalpa water. DON and DIN were removed by aluminium to about 30%. The DOC/DON and DIN/TDN ratios decreased with both coagulants in whole waters from both sources. The hydrophobic fraction contributed most to the formation of trihalomethanes, slightly hydrophobic acid being the biggest contributor. Lake water led to less THM formation than river water.
Research Article|February 01 2012
Removal of nitrogen and carbon organic matter by chitosan and aluminium sulphate
Indiana Garcia, Luis Moreno; Removal of nitrogen and carbon organic matter by chitosan and aluminium sulphate. Water Science and Technology: Water Supply 1 February 2012; 12 (1): 1–10. doi: https://doi.org/10.2166/ws.2011.111
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Our galaxy has a supermassive black hole at its centre as well, which has also ejected material at one time over the past few million years. While even light can not escape the pull of one of these gravity wells, blacks holes do, very occasionally, "burp" back out chunks of half-consumed gas.
The Hubble telescope then picked up clouds of blue-green gas emerging from the black hole from a previous burp. Investigators said that they are very fortunate that they observed this galaxy in a moment where they were able to see both these events very clearly.
Details of Comerford and her team's study were published in the The Astrophysical Journal and presented January 11 at the meeting of the American Astronomical Society in Washington, D.C.More news: NRI held for molesting United States national
"We are seeing this object feast, burp and nap, and then feast and burp once again, which theory had predicted", said lead author of the study Julie Comerford of the University of Colorado at Boulder's Department of Astrophysical and Space Science in a statement.
For comparison, one light-year is approximately 6 trillion miles.
The Hubble and Chandra space telescopes detected the burp 800million light-years away. The Apache Point facility is owned by the Astrophysical Research Consortium, a group of 10 USA research institutions that includes CU Boulder.
Investigating J1354, Chandra detected a supermassive black hole, millions or billions of times more massive than the Sun, at the centre of the galaxy, embedded in a thick cloud of gas and dust. Comerford said that these events of bubbles appear after a black hole feeding process.More news: Wesley Mathews indicted for capital murder
So why did the black hole have two separate meals?
Ms Comerford stated: "There's a stream of stars and gas connecting these two galaxies".
This may not even be all that rare of an occurrence, if the supermassive black hole at the center of the galaxy named "SDSS J1354+1327" can be taken as a typical example of these hungry monsters. "This new burp is actually moving like a shock wave - it's coming out very fast, and so it's kind of like a sonic boom of a burp, whereas the gas to the south shows us an older burp that happens 100,000 years earlier before that newer burp". In 2010 another research team discovered a Milky Way belch using observations from the orbiting Fermi Gamma-ray Observatory to look at the galaxy edge on. She added that if our solar system was close to the black hole than it would be hazardous for us.More news: Suspect Arrested And Charged For Killing Rihanna's Cousin Tavon Kaiseen Alleyne | <urn:uuid:e4d3680f-f51e-4ea3-9d74-5b98f5c16ba9> | 3.625 | 572 | News Article | Science & Tech. | 43.275614 | 95,547,298 |
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Up to this point, the systems under consideration have been homogeneous solutions. For the biological scientist, these solutions represent an extremely simplified set of conditions, those of a system that, while containing a number of constituents, contains them in a single homogeneous phase. (A phase is considered to be a state in which there is both chemical and physical uniformity.) This simplification has been valuable because through it general concepts have been developed and introduced. However, in a biological system, such a presumption is not realistic. The nature of biology is that of heterogeneous systems. Many of the processes in cells and living organisms involve the transfer of chemical species from one phase to another. For example, the movement of ions across a membrane such as the cell membrane or an intracellular organelle is often treated as transport between two phases, one inside and the other outside. The nature of the equilibria that can exist between phases will be the focus of this section. When different phases come in contact with each other, an interface between them occurs. This interface is a surface, and the properties of a surface are different from those of either of the phases responsible for creating it. The thermodynamic treatment of the properties of surfaces will be the subsequent focus of this section.
KeywordsSurface Tension Phase Equilibrium Activity Coefficient Osmotic Pressure Bulk Phase
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A repository & source of cutting edge news about emerging terahertz technology, it's commercialization & innovations in THz devices, quality & process control, medical diagnostics, security, astronomy, communications, applications in graphene, metamaterials, CMOS, compressive sensing, 3d printing, and the Internet of Nanothings. NOTHING POSTED IS INVESTMENT ADVICE! REPOSTED COPYRIGHT IS FOR EDUCATIONAL USE.
A combination of supercomputer calculations and a bombardment of high-energy particles has revealed how a new kind of material opens its pores and 'breathes'. Metal-organic frameworks (MOFs), are formed from building blocks made up of metal ions connected by organic molecules. These molecular blocks assemble themselves to produce a variety of crystal-like structures whose porous nature and ‘shape-shifting’ abilities could make them ideal for emerging applications, such as trapping greenhouse gases or delivering drugs.
'One of the key selling points of MOFs is the exceptionally large internal surface area that some of the frameworks can possess,' Matthew Ryder, a DPhil student in the Multifunctional Materials & Composites (MMC) Laboratory at Oxford University's Department of Engineering Science, tells me. 'Some MOFs have internal surface areas as large as 10,000 square metres per gram and to put that into perspective, that's a larger surface than a football field in every gram of MOF material!'
Whilst MOFs are similar to traditional microporous materials, such as inorganic zeolites or the activated carbons used to filter drinking water or air, they typically have a surface area ten times greater and can be processed at much lower temperatures. MOFs can also be built from a wider range of metal ions and organic links so that the desirable characteristics, such as pore size and its functionality, can be 'fine-tuned'.
Unlike activated carbons, MOFs are highly crystalline and this means that their 3D crystal structure can be precisely determined using diffraction techniques, such as X-rays and neutrons. Accurate 3D representations of MOF structures are central to computational modelling studies.
'It has been suggested for some time that the practical functionalities of each specific MOF material is intrinsically controlled by its elastic responses and collective vibrations of the porous framework (called 'lattice dynamics') down at the molecular scale,' Matthew explains.
In a study recently published in Physical Review Letters the team, led by Oxford's Professor Jin-Chong Tan, reports a new method for investigating how MOFs vibrate. They tested their ideas on a subclass of MOF materials: Zeolitic Imidazolate Frameworks (ZIFs).
Their method used Density Functional Theory (DFT) to unravel the complete vibrational nature of the frameworks at the molecular level. These calculations were so demanding that they could only be accomplished on state-of-the-art supercomputers (at ARC in Oxford, SCRAF at Rutherford Appleton Laboratory in Harwell, and the SuperMUC Petascale System near Munich). The theory was then confirmed using high-resolution spectroscopic experiments at Diamond Light Source and the ISIS Pulsed Neutron & Muon Source at Harwell, Oxford.
The team found that the experiments closely matched the theoretical DFT predictions across the entire vibrational spectra and discovered that the most exciting MOF framework vibrational behaviour was located in the low-energy or 'Terahertz (THz) region'.
'We demonstrated for the first time that the Terahertz modes not only show the standard lattice vibrations, but also reveal all of the physical characteristics unique to the specific MOFs we studied (ZIF-4, ZIF-7 and ZIF-8),' Matthew tells me.
'Our results revealed intriguing Terahertz vibrational modes [watch animations here], which include co-operative 'gate-opening' and 'breathing' of the nano-sized pores of MOFs, crucial for the understanding of gas separation, storage, and sensing.
'Significantly, this study enabled us to gain new insights into mechanical properties of MOFs, elucidating possible phase change mechanisms (called 'soft modes') through which the porous framework may destabilise, distort or even collapse when subject to mechanical forces, thereby completely destroying their functionality. Furthermore, soft modes may give rise to anomalous and counter-intuitive mechanical behaviour, such as negative thermal expansion and auxeticity.'
By studying the Terahertz vibrations in MOFs the researchers believe they could pinpoint and overcome deformation mechanisms that could otherwise make them difficult to use commercially.
Understanding how MOFs vibrate, change shape, and 'breathe', could also make it possible to enhance how they trap specific gas molecules – such as greenhouse gases – and help to tailor them for the targeted delivery of anti-cancer drugs.
'Interestingly, the latest research into MOFs has concentrated on other less conventional applications of porous materials: everything from microelectronics and information storage, to water splitting for sustainable hydrogen production and solar energy harvesting (photovoltaics) for clean electricity generation,' Professor Tan comments.
'Engineers, materials scientists and chemists have a big role to play to ensure the future success of MOFs. Discovering more about the mechanical properties and long-term durability of these materials will be key to realising their full potential and making the leap from the laboratory into large-scale commercial applications.'
Paper: Identifying the Role of Terahertz Vibrations in Metal-Organic Frameworks: From Gate-Opening Phenomenon to Shear-Driven Structural Destabilization - Matthew R. Ryder, Bartolomeo Civalleri, Thomas D. Bennett, Sebastian Henke, Svemir Rudić, Gianfelice Cinque, Felix Fernandez-Alonso and Jin-Chong Tan - Phys. Rev. Lett. 113, 215502, DOI: http://dx.doi.org/10.1103/PhysRevLett.113.215502 | <urn:uuid:c5e16304-991f-48ba-9548-36f4b855abf5> | 3.109375 | 1,255 | Academic Writing | Science & Tech. | 16.34167 | 95,547,338 |
A team of Chinese and American scientists has learned how to maintain high fusion performance under steady conditions by exploiting a characteristic of the plasma itself: the plasma self-generates much of the electrical current needed for plasma containment in a tokamak fusion reactor. This self-generated, or "bootstrap," current has significant implications for the cost-effectiveness of fusion power.
Magnetic fusion energy research uses magnetic fields to confine the fusion fuel in the form of a plasma (ionized gas) while it is heated to the very high temperatures (more than 100 million degrees) necessary for the ions to fuse and release excess energy that can then be turned into electricity.
The most developed approach uses the tokamak magnetic confinement geometry (a torus shaped vessel), and it is the basis for ITER, a 500-MW heat generating fusion plant currently being built in France by a consortium of seven parties—China, the European Union, India, Japan, Russia, South Korea and the United States.
In the tokamak configuration, the confining magnetic field is generated by external coils and by an electric current flowing within the plasma. The cost of driving these currents has a strong impact on the economic attractiveness of a fusion reactor based on the tokamak approach. One step to minimizing this cost is to make the external coils of superconducting wire.
The second step is to take full advantage of a surprising feature of the tokamak configuration: under certain conditions the electric current in the plasma can be generated by the plasma itself ("bootstrap" current).
The recent joint experiment, carried out on the DIII-D National Fusion Facility at General Atomics in San Diego, involved scientists from the DIII-D tokamak and from the Experimental Advanced Superconducting Tokamak (EAST), a fusion energy research facility at the Institute of Plasma Physics, Chinese Academy of Sciences (ASIPP) in Hefei, China.
Building on earlier DIII-D work, the experiment found that it is feasible for a tokamak to operate reliably at high fusion performance with most (more than 85 percent) of its plasma current consisting of bootstrap current. These conditions were maintained for several seconds, beyond the characteristic time scale of the plasma current evolution, and limited only by DIII-D pulse length constraints.
"It is often said that a plasma with a high fraction of self-generated (bootstrap) current would be difficult to control. However, these experiments show that a high bootstrap fraction plasma is very stable against transients: the plasma seems to 'like' a state where a large fraction of the current is self-generated," said Dr. Andrea Garofalo, General Atomics scientist and co-leader of the joint experiment.
These results build the foundation for follow-up experiments to be conducted on EAST, where the superconducting coils enable extension to very long pulse, and verification of the compatibility of this regime with reactor relevant boundary conditions.
ASIPP Director Prof. Jiangang Li remarked, "After the successful joint experiments in DIII-D, I am fully convinced that the DIII-D results can be reproduced on EAST in the near future, which will help us achieve the demonstration of high fusion performance in long pulse tokamak discharges."Research Contact:
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Scaffolding and specialised workers help with the delivery – Heidelberg biochemists gain new insights into biogenesis
A type of scaffolding on which specialised workers ply their trade helps in the manufacturing process of the two subunits from which the ribosome – the protein factory of the cell – originates. Biochemists at Heidelberg University discovered it after succeeding in getting a peek into the ribosomal “birthing room”.
While studying baker's yeast as the model organism, the researchers, in collaboration with colleagues from Ludwig Maximilian University of Munich, discovered a shell that envelops the smaller of the two subunits during the ribosome's formation.
The results of the research could contribute to a greater understanding of ribosomopathies – abnormalities caused by impaired ribosome biogenesis. Because several medications also act on the biogenesis of ribosomes, the investigators hope to apply their findings to cancer research. The results of the research were published in the journal “Cell”.
The research team of Prof. Dr Ed Hurt of the Heidelberg University Biochemistry Center had already stumbled on the earliest known ribosomal precursor, the 90S pre-ribosome, 15 years ago. To find out the function of this giant precursor particle in ribosome biogenesis, Markus Kornprobst isolated the pre-ribosomes of baker's yeast in order to analyse their structure.
“In the process, we discovered that the precursor bore a large shell-like module that the cell recycled after work was finished,” explains Markus Kornprobst of Prof. Hurt's team. “The relatively compact phenotype of the 90S pre-ribosome gave us the idea that this shell, in combination with other factors, encloses the smaller of the two ribosomal subunits during biogenesis to allow seamless assembly of the particle in a protected environment.” Using cryo-electron microscopy, they were able to confirm their suspicion in collaboration with the Munich team of Prof. Dr. Roland Beckmann.
Another member of Dr. Hurt's lab, Dr Nikola Kellner, isolated the 90S pre-ribosome from a heat-loving fungus. “They are more stable and hence better suited to further analyses than 90S pre-ribosomes from other organisms,” Nikola Kellner explains.
Finally, with the aid of cryo-electron microscopy, the structure of this thermostable 90S pre-ribosome was detectable down to a resolution of less than a nanometre. “The 90S factors actually form a gigantic cohesive network that surrounds the small developing subunit like a scaffold, such as on a high-rise, where specialized workers perform their jobs using various tools,” explains Ed Hurt.
M. Kornprobst, M. Turk, N. Kellner, et al.: Architecture of the 90S Pre-ribosome: A Structural View on the Birth of the Eukaryotic Ribosome. Cell 166 (July 14, 2016), doi: 10.1016/j.cell.2016.06.014
Model of the small ribosomal subunit shown at its “birth”. Within the 90S pre-ribosome – the earliest known intermediate in ribosome biogenesis – the nascent small ribosomal subunit is encapsulated by a giant network of biogenesis factors (“workers”). In analogy, the image illustrates how a construction scaffold is decorated with workers, who use tools for hammering, trimming, and burnishing, in order to sculpture the small subunit (shown yellow and blue) in its centre.
Figure: BZH/Jochen Baßler
Prof. Dr. Ed Hurt
Heidelberg University Biochemistry Center
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Marietta Fuhrmann-Koch | idw - Informationsdienst Wissenschaft
Barium ruthenate: A high-yield, easy-to-handle perovskite catalyst for the oxidation of sulfides
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For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
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The Brightest Galaxy In The Universe Is Surprisingly Young And Tiny
“In 2015, a new record was set for the brightest known galaxy, thanks to observations with the WISE telescope. Supermassive black holes power Extremely Luminous Infrared Galaxies. The brightest ones shine 10,000+ times as bright as our Milky Way.Although the Universe is just 10% of its current age and the galaxy is even smaller than ours, it outshines them all.”
I want you to close your eyes and imagine the Milky Way: a typical galaxy. Now, imagine a different galaxy, the brightest one you can think up. What does it look like? How do you imagine it?
Do you imagine something large, massive, with hundreds or even thousands of times as many stars? Do you imagine something that’s built itself up over billions of years? Well if that’s what you imagined, prepare to be shocked! The brightest ones of all are young, ultra-distant, and even smaller than our own galaxy!
Ask Ethan: Could The Universe Be Torn Apart In A Big Rip?
“Is The Big Rip—where expansion exceeds all the other forces—still considered a possible future for our Universe? What are the arguments for or against? And if so, how would it unfold, what would happen?”
In addition to normal matter, dark matter, neutrinos, and radiation, the Universe is made up of dark energy: a new form of energy intrinsic to space itself. Although the data indicates that dark energy is consistent with being a cosmological constant, whose energy density won’t change with time, it’s possible that this energy will increase or decrease in strength. If it decreases, it could decay entirely or even reverse sign. resulting in a Big Crunch. But if it increases, we could have a spectacularly catastrophic fate: the Big Rip. In the Big Rip, bound objects will literally be ripped apart on galactic, stellar, planetary, and eventually even atomic scales. Even space itself will rip apart in the end.
NASA’s Next Flagship Mission May Be A Crushing Disappointment For Astrophysics
“This is NASA. This is the pre-eminent space agency in the world. This is where science, research, development, discovery, and innovation all come together. The spinoff technologies alone justify the investment, but that’s not why we do it. We are here to discover the Universe. We are here to learn all that we can about the cosmos and our place within it. We are here to find out what the Universe looks like and how it came to be the way it is today.
It’s time for the United States government to step up to the plate and invest in fundamental science in a way the world hasn’t seen in decades. It’s time to stop asking the scientific community to do more with less, and give them a realistic but ambitious goal: to do more with more. If we can afford an ill-thought-out space force, perhaps we can afford to learn about the greatest unexplored natural resource of all. The Universe, and the vast unknowns hiding in the great cosmic ocean.”
While the Trump administration just proposed a new branch of the military, a “space force” if you will, NASA has just demanded that every one of the proposed astrophysics flagship missions abandon their large ambitions and present a scaled-down, sub-$5 billion version of their proposal. That means smaller telescopes, reduced capabilities, and less knowledge that will be revealed about the Universe. Every single one of the four will suffer from this, but the biggest losers may be us. In terms of science, society, spinoffs, and civilization, we’ll all be poorer if we fail to invest in something that truly makes a difference in this world.
Are Space And Time Quantized? Maybe Not, Says Science
“Incredibly, there may actually be a way to test whether there is a smallest length scale or not. Three years before he died, physicist Jacob Bekenstein put forth a brilliant idea for an experiment where a single photon would pass through a crystal, causing it to move by a slight amount. Because photons can be tuned in energy (continuously) and crystals can be very massive compared to a photon’s momentum, it ought to be possible to detect whether the “steps” that the crystal moves in are discrete or continuous. With a low-enough energy photon, if space is quantized, the crystal would either move a single quantum step or not at all.”
When it comes to the Universe, everything that’s in it appears to be quantum. All the particles, radiation, and interactions we know of are quantized, and can be expressed in terms of discrete packets of energy. Not everything, however, goes in steps. Photons can take on any energy at all, not just a set of discrete values. Put an electron in a conducting band, and its position can take on a set of continuous (not discrete) values. And so then there’s the big question: what about space and time? Are they quantized? Are they discrete? Or might they be continuous, even if there’s a fundamental quantum theory of gravity.
New Stars Turn Galaxies Pink, Even Though There Are No ‘Pink Stars’
“New star-forming regions produce lots of ultraviolet light, which ionizes atoms by kicking electrons off of their nuclei.
These electrons then find other nuclei, creating neutral atoms again, eventually cascading down through its energy levels.
Hydrogen is the most common element in the Universe, and the strongest visible light-emitting transition is at 656.3 nanometers.
The combination of this red emission line — known as the Balmer alpha (or Hα) line — with white starlight adds up to pink.”
When you look through a telescope’s eyepiece at a distant galaxy, it will always appear white to you. That’s because, on average, starlight is white, and your eyes are more sensitive to white light than any color in particular. But with the advent of a CCD camera, collecting individual photons one-at-a-time, you can more accurately gauge an astronomical object’s natural color. Even though new stars are predominantly blue in color, star-forming regions and galaxies appear pink. The problem compounds itself when you realize there isn’t any such thing as a pink star! And yet, there’s a straightforward physical explanation for what we see.
Hubble Catches New Stars, Individually, Forming In Galaxies Beyond The Milky Way
“There are a massive variety of star-forming regions nearby, and Hubble’s new Legacy ExtraGalactic UV Survey (LEGUS) is now the sharpest, most comprehensive one ever.
By imaging 50 nearby, star-forming spiral and dwarf galaxies, astronomers can see how the galactic environment affects star-formation.”
Within galaxies, new stars are going to be formed from the existing population of gas. But how that gas collapses and forms stars, as well as the types, numbers, and locations of the stars that will arise, is highly dependent on the galactic environment into which they are born. Dwarf galaxies, for example, tend to form stars when a nearby gravitational interaction triggers them. These bursts occur periodically, leading to multiple populations of stars of different ages. Spirals, on the other hand, form their new stars mostly along the lines traced by their arms, where the dust and gas is densest. Thanks to the Hubble Space Telescope, we’re capable of finding these stars and resolving them individually, using a combination of optical and ultraviolet data.
Astronomers Confirm Second Most-Distant Galaxy Ever, And Its Stars Are Already Old
“Scientists have just confirmed the second most distant galaxy of all: MACS1149-JD1, whose light comes from when the Universe was 530 million years old: less than 4% of its present age. But what’s remarkable is that we’ve been able to detect oxygen in there, marking the first time we’ve seen this heavy element so far back. From the observations we’ve made, we can conclude this galaxy is at least 250 million years old, pushing the direct evidence for the first stars back further than ever.”
When it comes to the most distant galaxies of all, our current set of cutting-edge telescopes simply won’t get us there. The end of the cosmic dark ages and the dawn of the first cosmic starlight is a mystery that will remain until at least 2020: when the James Webb Space Telescope launches. Using the power of a multitude of observatories, we’ve managed to find a gravitationally lensed galaxy whose light comes to us from over 13 billion years ago. But unlike previous galaxies discovered near that distance, we’ve detected oxygen in this one, allowing us to get a precise measurement and to estimate its age.
The Ring Is A Lie: Ring Nebula Not A Ring After All
“Upon observing it, Charles Messier wrote: “it is very dull, but perfectly outlined; it is as large as Jupiter & resembles a planet which is fading.”
This is where the term planetary nebula comes from: where dying stars blow off their outer layers.
But despite looking very much like a ring to our eyes, the Ring Nebula is anything but.”
There are few objects in the night sky as famous or striking as the Ring Nebula. Discovered way back in 1779, its visual, ring-like shape can easily be seen with the human eye through even a modest telescope. But despite its appearances, it’s no ring at all. There’s a large, diffuse outer halo, a series of intricate, extended, knotty hydrogen structures, two lobes that extend even larger than the ring component but along our line-of-sight, and finally that bright, high-density donut that appears ring-like to our eyes. At just over 2,000 light years away, it is the closest planetary nebula to Earth, and the template for what we think will happen to our Solar System when the Sun dies.
When Will We Break The Record For Most Distant Galaxy Ever Discovered?
“Finally, beyond a certain distance, the Universe hasn’t formed enough stars to reionize space and make it 100% transparent.
We only perceive galaxies in a few serendipitous directions, where copious star-formation occurred.
In 2016, we fortuitously discovered GN-z11 at a redshift of 11.1: from 13.4 billion years ago.
But recent, indirect evidence suggests stars formed at even greater redshifts and earlier times.“
It was only a couple of years ago that we set the current record for where the most distant galaxy is: from 13.4 billion years ago, when the Universe was just 3% its current age. This record is unlikely to be broken with our current set of observatories, as discovering a galaxy this distant required a whole bunch of unlikely, serendipitous phenomena to line up at once. But in 2020, the James Webb Space Telescope will launch: an observatory optimized for finding exactly the kinds of galaxy that push past the limits of what Hubble can do. We fully expect to not only break the record for most distant galaxy ever discovered, but to learn, for the first time, exactly where and when the first galaxies in the Universe truly formed. | <urn:uuid:6aad7559-5e5a-41e6-b086-a7c5d6510fd4> | 3.359375 | 2,417 | Content Listing | Science & Tech. | 48.734957 | 95,547,389 |
Web Development Tutorial: PHP vs. Python & Django
In this tutorial, we'll compare PHP and Python (Django) for web development then we'll see how to create simple demo apps with PHP and Python (using Django one of the most popular frameworks for Python).
PHP is a programming languages which has a sole purpose to create back-end web applications while Python is a general purpose programming language that can be used for web development and other fields such as data science and scientific calculations so our comparison will be between PHP and Python equipped with a web framework. The most popular web frameworks for Python are Django and Flask with Django being more popular than Flask.
In order to compare PHP with Django we need to consider many factors such as:
- Are your a beginner or experienced developer?
- Are looking for quick insertion in the job market? etc.
More experienced developers have more potential to quickly learn a new programming language than beginners
Both PHP and Python are popular languages. They are both extremely popular among web developers and power most of the websites on the web today.
Let's take a look at these three factors:
- Popularity of PHP and Python with Django for web development
- The learning curve for Python, Django and PHP
- The available libraries and packages, learning resources and the community
Both PHP (dominates 80% of the market)and Python are popular languages, but for web development PHP is more popular than the most popular framework for web development in Python which is Django.
Popular websites like Facebook and Wikipedia are built in PHP.
Also many popular website and apps that you use daily are using Python. For example, YouTube, Reddit, Pinterest and Instagram etc.
A learning curve describes how easy or difficult the programming language is? Which simply means how easy to become familiar with the programming syntax and to start implementing requirements using the language.
Python is a lot easier than PHP since it has clear and readable syntax so for a beginner developer it would be easier to learn. Many universities in the world are using Python as the first programming language for their students.
On the other hand, PHP has a less readable and confusing syntax which makes the learning process for a beginner developer more difficult, but to be fair, once your learn and become familiar with the syntax you can start creating websites with the same ease.
Batteries and libraries
PHP has many libraries, frameworks and CMSs than Python. For example WordPress, the most popular CMS platfrom which everyone is using create a website is built in PHP. Also popular eCommerce solutions like Magento and WooCommerce are developed in PHP. Python with Django also offers many libraries a quite a few CMSs but not as equal to PHP.
Now let's see a list of pros and cons for both Python (and as a result Django) and PHP:
Let's start with Python pros and cons:
- Python is a popular general purpose programing language,
- Python is considered one of the most liked programming language by developers,
- Easy to learn,
- Has very readable syntax,
- Web apps created in Python are safer and more scalable
The pros and cons of PHP:
- PHP is the most popular programming language designed only for creating server web applications. 80% of websites in the Internet are powered by PHP
- PHP is the most hated programming language by developers
- Easier to learn but has confusing syntax for beginners
- PHP is less secure than other programming languages designed for web development
The best recommendation, for beginner developers is to try out both languages and then choose the one they are more comfortable with. But you need also to consider the job market and learning resources. Python is easier to learn while PHP offers you a better chance for quickly getting a job and has more learning resources around the world. | <urn:uuid:da79d212-b9fe-49b1-a7a9-e5343ada121d> | 2.9375 | 776 | Tutorial | Software Dev. | 38.831399 | 95,547,395 |
A team of researchers from the Berkley Lab at the Department of Energy organized a deep study of two meteorites that fell on Earth in the year 1998 to find evidence proving the presence of liquid water as well as a well-structured mix of complex organic compounds that included amino acids as well as hydrocarbons.
"Our coordinated organic analysis of the salt crystals suggest that the organic matter originated from a water-rich, or previously water-rich parent body - an ocean world in the early solar system, possibly Ceres, "said planetary scientist Queenie Chan, study author and postdoctoral research associate at The Open University in the UK".
Confirming that these compounds that are so important to life as we know it can fall to Earth in this way isn't proof that they triggered the beginnings of life, but it does mean that scenario is a real possibility.
Zag/Monahans meteorites and their salt (halite) crystals: (A) diagram showing the lithologies of the Zag and Monahans meteorites, their dark (carbonaceous) clasts, the salt crystals, and the fluid and solid inclusions within the salt crystals; (B) salt crystals hosted in the matrix regions of the Zag meteorite; the arrow marks one of the several salt crystals shown in this photo; (C) a microphotograph showing a salt crystal sampled from the Zag meteorite; (D) salt crystals sampled from the Zag meteorite contained in a pre-sterilized glass ampoule before hot-water extraction.
While life-supporting elements like these have been discovered in space rocks in the past, this is the first time water and organic matter associated with it has been found at the same place. Upon close observation, scientists found traces of liquid water that dated to a time that was the initial stage of our solar system which is 4.5 billion years old.
Extensive analysis of the salt crystals also revealed the probable origins of the meteorites, including the dwarf planet Ceres and asteroid Hebe as major objects in the asteroid belt. It turns out that this space rock, along with another that fell in Morocco that same year, contained traces of liquid water and organic compounds vital to life.More news: Everything President Trump has tweeted (and what it was about)
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The finding was made by an worldwide team of researchers, which included scientists from the Open University (OU) in the United Kingdom and Nasa's Johnson Space Centre in Texas.
That makes them enticing for further study, so an global team of scientists analyzed the organic compounds in 2-mm long salt crystals inside the two meteorites.
The two meteorites, which yielded the two-millimetre-sized salt crystals, were preserved at NASA's Johnson Space Center in Texas. "There is a great range of organic compounds within these meteorites, including a very primitive type of organics that likely represent the early solar system's organic composition".
The Science Advances published the abstract of the study.
Scientists believe that this discovery leads to the conclusion that the origin of life is possible elsewhere. | <urn:uuid:9fc1884c-b1b8-463a-8df3-a8d968faf785> | 3.046875 | 666 | News Article | Science & Tech. | 25.236195 | 95,547,410 |
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Ask a Scientist: Where the sun goes at night
Kopernik Observatory & Science Center hosts nearly 1000 guests for the solar eclipse. High tech or low tech they had the eclipse covered. Patrick Oehler/Staff Video
QUESTION: Why does the sun not shine at night?
ANSWER: The truth is that the sun is always shining and will shine continuously until it dies.
The question to answer here is “Why do we not see the sun at night, and why do we only see it during the day?” Technically, we say “day” to mean when we can see the sun shining, and “night” when we have no sunlight. Let’s understand how the cycle of day and night works in our solar system.
Our solar system consists of the sun, planets, moons of planets, asteroids, meteors, comets and other interplanetary media. The sun is the main source of energy, and it rotates on its own axis. The planets rotate on their own axis as well as they revolve around the sun due to gravitation pull.
The moons to different planets also rotate on their own axis, revolving around their planets as well as revolving around the sun.
Earth is a medium-size planet that rotates with a tilted axis at an angle of 23.44 degrees. It completes one rotation in 23 hours, 56 minutes and 4.09 seconds, which is approximately one day on Earth.
The part of Earth which faces the sun during rotation gets sunlight, and almost half of the Earth does not get sunlight at that instant. The part of Earth getting sunlight feels that the sun is shining, and it is daytime for them. The other part of Earth having no sunlight feels that the sun is not shining, and it is night for them.
So, one complete rotation of Earth gives us a complete cycle of day and night. It takes approximately 24 hours to complete the Earth’s rotation, out of which we feel 12 hours as night and 12 hours of day. This cycle of day and night on Earth will continue to take place until the sun dies completely and stop shining.
Meet the student
Name: Leila Lewis
School: St. John the Evangelist, Broome County Catholic Schools.
Teacher: Anu Rai.
Career interests: Police officer.
Meet the scientist
Answered by: Gautam Ranjan.
Title: Graduate student, Department of Mechanical Engineering, Binghamton University.
Research area: Composites, 3-D printing, finite element method, design and optimization, Mars mission, entrepreneurships.
Interests/hobbies: Running, martial arts, cooking, networking.
Ask a Scientist runs on Sundays. Questions are answered by science experts at Binghamton University. Teachers in the Greater Binghamton area who wish to participate in the program are asked to write to Ask a Scientist, c/o Binghamton University, Office of Communications and Marketing, PO Box 6000, Binghamton, NY 13902-6000, or e-mail firstname.lastname@example.org. For more information, visit binghamton.edu/mpr/ask-a-scientist/. | <urn:uuid:ba20c881-45cd-4536-b148-faba23409e17> | 3.453125 | 685 | Q&A Forum | Science & Tech. | 59.582152 | 95,547,433 |
Recent research results from scientists at the Woods Hole Research Center suggest that greening has begun to decline in the high latitude forested areas of North America. The work, which represents an important advance by incorporating the full extent of the latest satellite observational record to document unique vegetation responses to climatic warming, and then projecting those trends forward in time, is now being extended to circumpolar forests. The research will be highlighted in upcoming issues of Proceedings of the National Academy of Sciences (PNAS) and in Geophysical Research Letters.
Generally, satellite observations of plant growth across the high latitudes of North America -- in Canada and Alaska -- indicate that tundra vegetation experienced an increase in both peak photosynthesis and growing season length, whereas forests experienced a decline in photosynthetic activity between 1981 and 2003. Climatic warming occurred across the entire region, but the change in the forest response indicates that long-term changes may not be predictable from initial, short-term observations. Fire disturbance has also increased with the warming but does not explain the decline in forest photosynthetic activity.
According to Scott Goetz, a senior scientist with the Center, "We believe this is some of the first evidence that high latitude forests may be in decline following an initial growth spurt associated with warming. The reasons for this decline are not certain, but related work points to increased drying as a likely cause. The observed warming and drying are consistent with climate model predictions for the region."
Elizabeth Braun | EurekAlert!
Upcycling of PET Bottles: New Ideas for Resource Cycles in Germany
25.06.2018 | Fraunhofer-Institut für Betriebsfestigkeit und Systemzuverlässigkeit LBF
Dry landscapes can increase disease transmission
20.06.2018 | Forschungsverbund Berlin e.V.
A new manufacturing technique uses a process similar to newspaper printing to form smoother and more flexible metals for making ultrafast electronic devices.
The low-cost process, developed by Purdue University researchers, combines tools already used in industry for manufacturing metals on a large scale, but uses...
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
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20.07.2018 | Materials Sciences | <urn:uuid:2831b9e8-ad9d-4625-a355-8361f911c180> | 3.4375 | 899 | Content Listing | Science & Tech. | 32.981184 | 95,547,448 |
The relative abundances of 18 selected taxonomic groups of Radiolaria were determined for 145 trigger-weight core-top samples collected between long 80°E and 55°W and lat 35°S and 60°S. Seventy-two samples were considered to represent nonreworked recent sediments. A factor analysis of these 72 samples resolved Antarctic, subantarctic, and subtropical assemblages, with distributions closely corresponding to the main surface water masses in the area.
Using the technique of Imbrie and Kipp, paleoecologic equations have been developed to estimate surface-water temperatures for August (winter) and February (summer). Estimated temperatures range from near 20°C in the northern parts of the area to 0°C at the location of the southernmost cores. The standard error of estimate of the equations is less than 1.5°C. The CaCO3 content of the 145 surface-sediment samples shows that variations in the calcite compensation depth (CCD) for locations north of the Antarctic Polar Front depends mainly on varying dissolution. The CCD is about 4,800 m in the western basin of the Atlantic Ocean but is deeper than 5,200 m, at least locally, in the Indian Ocean. South of the Antarctic Polar Front the CCD is shallower than 3,700 m.
Radiolaria are common in most samples, with the maximum number per gram of sediment being found in samples collected near or beneath the Antarctic Polar Front. | <urn:uuid:407d1fd6-56a4-425c-a65a-f9bf6bd12020> | 2.75 | 305 | Academic Writing | Science & Tech. | 45.618701 | 95,547,453 |
Despite the longstanding reliability of the process, scientists have had little understanding of how it actually works. But now a team of chemists, led by Patrick Holland of the University of Rochester, has new insight into how the ammonia is formed. Their findings are published in the latest issue of Science.
Holland calls nitrogen molecules "challenging." While they're abundant in the air around us, which makes them desirable for research and manufacturing, their strong triple bonds are difficult to break, making them highly unreactive. For the last century, the Haber-Bosch process has made use of an iron catalyst at extremely high pressures and high temperatures to break those bonds and produce ammonia, one drop at a time. The question of how this works, though, has not been answered to this day.
"The Haber-Bosch process is efficient, but it is hard to understand because the reaction occurs only on a solid catalyst, which is difficult to study directly," said Holland. "That's why we attempted to break the nitrogen using soluble forms of iron."
Holland and his team, which included Meghan Rodriguez and William Brennessel at the University of Rochester and Eckhard Bill of the Max Planck Institute for Bioinorganic Chemistry in Germany, succeeded in mimicking the process in solution. They discovered that an iron complex combined with potassium was capable of breaking the strong bonds between the nitrogen (N) atoms and forming a complex with an Fe3N2 core, which indicates that three iron (Fe) atoms work together in order to break the N-N bonds. The new complex then reacts with hydrogen (H2) and acid to form ammonia (NH3) -- something that had never been done by iron in solution before.
Despite the breakthrough, the Haber-Bosch process is not likely to be replaced anytime soon. While there are risks in producing ammonia at extremely high temperatures and pressures, Holland points out that the catalyst used in Haber-Bosch is considerably less expensive than what was used by his team. But Holland says it is possible that his team's research could eventually help in coming up with a better catalyst for the Haber-Bosch process -- one that would allow ammonia to be produced at lower temperatures and pressures.
At the same time, the findings could have a benefit far removed from the world of ammonia and fertilizer. When the iron-potassium complex breaks apart the nitrogen molecules, negatively charged nitrogen ions -- called nitrides -- are formed. Holland says the nitrides formed in solution could be useful in making pharmaceuticals and other products.
Peter Iglinski | EurekAlert!
Scientists uncover the role of a protein in production & survival of myelin-forming cells
19.07.2018 | Advanced Science Research Center, GC/CUNY
NYSCF researchers develop novel bioengineering technique for personalized bone grafts
18.07.2018 | New York Stem Cell Foundation
A new manufacturing technique uses a process similar to newspaper printing to form smoother and more flexible metals for making ultrafast electronic devices.
The low-cost process, developed by Purdue University researchers, combines tools already used in industry for manufacturing metals on a large scale, but uses...
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
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Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
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20.07.2018 | Materials Sciences | <urn:uuid:80c886c0-fc89-4e14-8dc4-8e87deeab74c> | 3.8125 | 1,122 | Content Listing | Science & Tech. | 39.572682 | 95,547,456 |
Comparison of weather models for Barnstable
The blue lines correspond to the forecasts computed by different high-resolution weather models. Also shown are the members of a traditional ensemble prediction, where the same weather model (GFS) is run several times with slightly different initial conditions, to reflect uncertainties in the observations required to run a forecast model. The GFS members have been downscaled and bias corrected to match local weather conditions, data from the high-resolution models is untouched.
- In the top graph, the temperature forecast for Barnstable is shown using light blue for different high-resolution models and red for the GFS ensemble members. The black line represents the mean of all forecasts and the dashed line the meteoblue consensus forecast as shown in our weather forecasts.
- The 2nd graph shows the accumulated precipitation forecast, that is the total amount that falls from today up to the date shown on the time axis. Purple colour is used to indicate times where precipitation is falling.
- The 3rd graph is forecast cloud cover in percent using light blue for the high-resolution weather models and green for the GFS ensemble members.
- The 4th graph indicates the wind forecast as computed by high resolution models (light blue) and by the ensemble prediction (green). Also shown is the daily wind direction summary in form of a wind rose. Larger segments indicate that this wind direction is more likely and more frequent over the day than directions having smaller segments. If you have many segments of all about equal size than the forecast of wind direction is very uncertain. If there are predominantly two opposing directions this often indicates a thermal wind circulation where wind blows from a different direction during the day than at night.
Why do we show a traditional ensemble forecast and a multi model forecast at the same time?
A traditional ensemble (e.g. GFS) computed with the same forecast model often underestimates the uncertainties in the weather for the first 3 to 5 days thus overestimating the confidence in the forecast. Furthermore, the traditional ensemble is run at much lower resolution, thus neglecting some of the local weather phenomenon, which can be seen in high resolution models. It is very important to note, that all members of a traditional ensemble have the same likelihood of being true (there is no way to tell in advance which one will be better). This contrasts with the high-resolution models, where some deliver better forecasts than others depending on the location and weather conditions.
Weather models simulate physical processes. A weather model divides the world or a region into small "grid-cells". Each cell is about 4km to 40km wide and 100m to 2km high. Our models contain 60 atmospheric layers and reach deep into the stratosphere at 10-25 hPa (60km altitude). The weather is simulated by solving complex mathematical equations between all grid cells every few seconds and parameters like temperature, wind speed or clouds are stored for every hour.
meteoblue operates a large number of weather models and integrates open data from various sources. All meteoblue models are computed twice a day on a dedicated High Performance Cluster.
NEMS model family: Improved NMM successors (operational since 2013). NEMS is a multi-scale model (used from global down to local domains) and significantly improves cloud-development and precipication forecast.
|NEMS4||Central Europe||4 km||72 h||03:03 EDT||meteoblue|
|NEMS12||Europe||12 km||180 h||03:37 EDT||meteoblue|
|NEMS2-12||Europe||12 km||168 h||04:20 EDT||meteoblue|
|NEMS-8||Central America||12 km||180 h||05:51 EDT||meteoblue|
|NEMS12||India||12 km||180 h||04:28 EDT||meteoblue|
|NEMS10||South America||10 km||180 h||06:24 EDT||meteoblue|
|NEMS10||South Africa||10 km||180 h||04:43 EDT||meteoblue|
|NEMS8||New Zealand||8 km||180 h||03:46 EDT||meteoblue|
|NEMS8||Japan East Asia||8 km||180 h||03:23 EDT||meteoblue|
|NEMS30||Global||30 km||180 h||01:33 EDT||meteoblue|
|NEMS2-30||Global||30 km||168 h||07:37 EDT||meteoblue|
NMM model family: the first weather model from meteoblue (operational since 2007). NMM is a regional weather model and highly optimised for complex terrain.
|NMM4||Central Europe||4 km||72 h||01:46 EDT||meteoblue|
|NMM12||Europe||12 km||180 h||03:28 EDT||meteoblue|
|NMM18||South America||18 km||180 h||05:34 EDT||meteoblue|
|NMM18||South Africa||18 km||180 h||03:38 EDT||meteoblue|
|NMM18||Southeast Asia||18 km||180 h||04:15 EDT||meteoblue|
Third-party domains: As seen on most other websites
|GFS22||Global||22 km||180 h (@ 3 h)||00:31 EDT||NOAA NCEP|
|GFS40||Global||40 km||180 h (@ 3 h)||01:00 EDT||NOAA NCEP|
|GFSENS05||Global||40 km||384 h (@ 6 h)||04:46 EDT||NOAA NCEP|
|NAM5||North America||5 km||48 h||01:25 EDT||NOAA NCEP|
|NAM12||North America||12 km||84 h (@ 3 h)||23:03 EDT||NOAA NCEP|
|ICON7||Europe||7 km||120 h (@ 3 h)||00:13 EDT||Deutscher Wetterdienst|
|ICON13||Global||13 km||180 h (@ 3 h)||01:45 EDT||Deutscher Wetterdienst|
|COSMO2||Germany and Alps||2.2 km||27 h||09:32 EDT||Deutscher Wetterdienst|
|GEM25||Global||25 km||168 h (@ 3 h)||02:05 EDT||Environment Canada|
|AROME2||France||2 km||36 h||01:15 EDT||METEO FRANCE|
|ARPEGE11||Europe||11 km||96 h||03:08 EDT||METEO FRANCE|
|ARPEGE40||Global||40 km||96 h (@ 3 h)||01:05 EDT||METEO FRANCE|
|HIRLAM11||Europe||11 km||48 h||01:32 EDT||KNMI|
meteoblue weather models cover most populated areas at high resolution (3-10km) and world wide at moderate resolution (30km). The map on the side displays NMM models as red and NEMS models as black boxes. For a single forecast, multiple weather models, statistical analysis, measurements, radar and satellite telemetry are considered and combined to generate the most probable weather forecast for any given location on Earth. | <urn:uuid:9334131e-3bd4-4199-9e99-a7827ab34138> | 2.578125 | 1,578 | Knowledge Article | Science & Tech. | 56.309045 | 95,547,457 |
Many universities now use Design Patterns Explained in their advanced software development courses simply. These C++ Code Examples help any students working with the book pdf torrent-reactor. EBook Details Paperback 117 pages Publisher sourcemaking com. Com 1st edition (November 25, 2015) Language English ISBN-10 n/a ISBN-13 Description Design [doc]design explained. Antenna pattern testing seconds The RFX is a compact bench-top scanner that characterizes antennas your own lab environment real-time doc. North North basic form object creation could result problems or added complexity creational solve this. Development Process by using the.
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On July 23, 2015, the FS METEOR set to sea for her second big research cruise this year. Starting from the port of Hamburg, the German open sea research vessel will spend the first month of the four-month expedition in the Baltic Sea. Under the lead of the Leibniz Institute for Baltic Sea Research Warnemünde (IOW) the research focus of this leg of the expedition lies on biochemical processes of upwelling zones in the Gotland Basin and the Gulf of Finland.
Upwelling is a process, which is initiated by certain wind regimes. Deep water that differs significantly from upper water layers is transported to the surface of the sea. Screened from the sun, it is much colder and enriched with nutrients and other dissolved substances, which have been released into the water by microbial degradation of organic matter at the sea floor.
The surface water, on the other hand, is significantly warmed up by solar energy during summer and mostly depleted of nutrients. “Upwelling zones are quite frequent in the Baltic Sea, but sometimes exist only for a few days. They are exciting ‘hotspots’ for marine researchers, because a lot is going on there.
The temperature drop, but mostly the supply of fresh nutrients alters the environment for the communities of planktonic organisms as well as the conditions for air-sea exchange processes on a very small temporal and spatial scale,” comments Günther Nausch on the research focus of METEOR cruise 117 titled “BioChemUpwell”.
As deputy chief scientist, the longstanding IOW expert for marine chemistry and matter cycles is responsible for the scientific coordination of the cruise together with chief scientist Oliver Wurl from the Institute for Chemistry and Biology of the Marine Environment (ICBM) in Oldenburg. “To study the upwelling events from as many angles as possible, five project groups from three different research institutions have joined forces to take advantage of the synergies of such a collaborative expedition,” adds Nausch.
26 scientists in total, amongst them 20 IOW researchers, participate in the METEOR cruise 117 as scientific crew. Group 1 under the lead of IOW addresses the interaction of the cold upwelling water, which transports nutrients – especially phosphorus– upwards, and the development of cyanobacteria blooms.
The research aims at supporting a better forecast and management of those blooms, which are potentially harmful for animals and humans. Group 2, headed by ICBM, explores the impact of the CO2 enriched deep water of upwelling systems on carbon fluxes and primary productivity at the surface.
In particular, the researchers investigate the formation of the micro-layers within upwelling zones and their impact on the air-sea CO2 exchange by using highly developed sensors as well as in-situ sampling devices especially developed for this expedition. Group 3 under the lead of the Leibniz Institute for Tropospheric Research (TROPOS) also concentrates on the interface of sea and atmosphere:
The scientists analyze the effect of upwelling zones on the composition of aerosols as these airborne climate relevant particles are significantly influenced by what kind of micro-layers exists on the sea surface. Group 4 under IOW lead investigates the sources of organic mercury compounds in oxygen depleted deeper water layers. Furthermore, the group analyzes, how the upward transport affects these substances and if – by consequence – an air-sea gas exchange of volatile mercury compounds increases the biological availability of these pollutants.
Group 5, also headed by IOW, examines, how the energy turnover within zooplankton communities changes in response to varying food quality. Such variability can be caused by upwelling events as they significantly affect the composition of phytoplankton, on which the zooplankton feeds. Last but not least, IOW project group 6 is responsible for the data collection within various long-term monitoring programs. This includes the measurement in varying depths of temperature, salinity and the concentration of nutrients, oxygen, and chlorophyll as well as the survey of phyto- and zooplankton composition.
The METEOR’s track to the Eastern Gotland Basin and to the Gulf of Finland is in parts flexible as the occurrence of upwelling zones cannot be predicted in time and space. “We will be able to recognize the current position of an upwelling zone by our routine measurements on board as the key parameters of the cold water from deeper layers differ very recognizably from those of the surface water.
In addition, we will cooperate closely with our land-based IOW colleagues from the remote sensing team, who will constantly supply us with satellite information on the sea surface temperature and the occurrence of sudden cold spots, which typically indicate an upwelling event,” explains Günther Nausch. The METEOR cruise 117 will be concluded on August 17, 2015, in Rostock, where the scientific crew of this particular part of the expedition will disembark. Afterwards, three more cruise legs will lead the METEOR into the Atlantic with her final destination in the port of Walvis Bay/Namibia.
More information on the research vessel METEOR:
*Press and Public Relations at IOW:
Dr. Kristin Beck | Tel.: 0381 – 5197 135 | firstname.lastname@example.org
Dr. Barbara Hentzsch | Tel.: 0381 – 5197 102 | email@example.com
The IOW is a member of the Leibniz Association with currently 89 research institutes and scientific infrastructure facilities. The focus of the Leibniz Institutes ranges from natural, engineering and environmental sciences to economic, social and space sciences as well as to the humanities. The institutes are jointly financed at the state and national levels. The Leibniz Institutes employ a total of 18.100 people, of whom 9.200 are scientists. The total budget of the institutes is 1.64 billion Euros. (http://www.leibniz-gemeinschaft.de/en/home/)
Dr. Kristin Beck | idw - Informationsdienst Wissenschaft
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
16.07.2018 | Physics and Astronomy
16.07.2018 | Life Sciences
16.07.2018 | Earth Sciences | <urn:uuid:3dbeb48c-2184-4ca8-a3f1-bfe550b26f2a> | 2.984375 | 1,924 | Content Listing | Science & Tech. | 39.1678 | 95,547,484 |
The Sun sporadically expels trillions of tons of million-degree hydrogen gas in explosions called coronal mass ejections (CMEs). Such clouds—an example is shown in Figure 1a—are enormous in size (spanning millions of miles) and are made up of magnetized plasma gases, so hot that hydrogen atoms are ionized.
CMEs are rapidly accelerated by magnetic forces to speeds of hundreds of kilometers per second to upwards of 2,000 kilometers per second in several tens of minutes. CMEs are closely related to solar flares and, when they impinge on the Earth, can trigger spectacular auroral displays.
They also induce strong electric currents in the Earth's plasma atmosphere (i.e., the magnetosphere and ionosphere), leading to outages in telecommunications and GPS systems and even the collapse of electric power grids if the disturbances are very severe.
Since the first observation of a solar flare in 1859, solar eruptions ("explosions") have attracted much attention from scientists around the world and have been studied with a succession of increasingly sophisticated international satellite missions in the past three decades. A major challenge has been that enormous and complicated plasma structures accelerating away from the Sun can only be observed remotely.
As a result, it has been difficult to test theoretical models to establish a correct understanding of the mechanisms that cause such eruptions. But in 2006, an international twin-satellite mission called STEREO was launched to continuously observe the erupting plasma structures from the Sun to the Earth.
Now, using the data from STEREO, new research by scientists at the Naval Research Laboratory (NRL) in Washington, D.C., demonstrates for the first time that the observed motion of erupting plasma clouds driven by magnetic forces can be correctly explained by a theoretical model. The work will be presented at the 52nd Annual Meeting of the APS Plasma Physics Division.
The theory, controversial when it was first proposed in 1989 by Dr. James Chen of NRL, is based on the concept that an erupting plasma cloud is a giant "magnetic flux rope," a rope of "twisted" magnetic field lines shaped like a partial donut. Chen and Valbona Kunkel, a doctoral student at George Mason University, have applied this model to the new STEREO data of CMEs and shown that the theoretical solutions agree with the measured trajectories of the ejected clouds within the entire field of view from the Sun to the Earth.
The position of the leading edge (LE) of a CME that erupted on December 24, 2007 were tracked by the STEREO-A spacecraft from the earliest stages of eruption to its arrival at 1 AU approximately five days later. The magnetic field and plasma parameters were measured by the STEREO-B spacecraft. The agreement between theory and data is within 1 percent of the measured position of the LE. Chen and Kunkel's results show that the theoretically predicted magnetic field and plasma properties are in excellent agreement with the measurements aboard STEREO-B. This is the first model that can replicate directly observed quantities near the Sun and the Earth as well as the actual trajectories of CMEs. Prior to STEREO, the motion of CMEs in the region corresponding to HI1 and HI2 data was not observed.
Interestingly, the basic forces acting on solar flux ropes are the same as those in laboratory plasma structures such as tokamaks developed to produce controlled fusion energy. The mechanism described by the theory is also potentially applicable to eruptions on other stars.
Saralyn Stewart | EurekAlert!
Subaru Telescope helps pinpoint origin of ultra-high energy neutrino
16.07.2018 | National Institutes of Natural Sciences
Nano-kirigami: 'Paper-cut' provides model for 3D intelligent nanofabrication
16.07.2018 | Chinese Academy of Sciences Headquarters
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
16.07.2018 | Physics and Astronomy
16.07.2018 | Life Sciences
16.07.2018 | Earth Sciences | <urn:uuid:cac91021-09f1-4fb1-afb8-51bdcbb7f298> | 3.9375 | 1,376 | Content Listing | Science & Tech. | 38.918656 | 95,547,485 |
After the release of ‘Alalā into their native Hawaiian habitat, researchers are beginning to notice increased vocalization.
‘Alalā, also known as Hawaiian Crows, had been considered Extinct-in-the-wild since 2002 with only captive populations left on Earth providing hope for the species’ survival. After decades of conservation, 11 ‘Alalā now fly free in the Pu‘u Maka‘ala Natural Area Reserve, Hawai’i. The species, which had once been driven to near-extinction due to predation by invasive species and habitat loss, now has a small population of thriving individuals.
After the first attempt at release, during which two individuals died due to natural predation, conservationists recaptured remaining individuals and increased their predator avoidance training in captivity. The theory was that the time in captivity altered their predator avoidance capabilities. Now, with enhanced training, the ‘Alalā are thriving even with natural predators. Researchers note that in captivity ‘Alalā were also less vocal, but their return to the wild has yielded more expression. Alison Greggor, Postdoctoral Associate with San Diego Zoo Global commented:
When the only existing ‘Alalā were living in the protected aviaries at the Keauhou Bird Conservation Center, we saw fewer types of alarm and territory calls in the population and the frequency of alarm calls was greatly reduced.
Vocalization is thought to be an important wild behavior for the species that is necessary for survival in their native forests. Joshua Pang-Ching, Research Coordinator of the San Diego Zoo Global’s Hawai’i Endangered Bird Conservation Program explained:
We are beginning to observe behaviors that appear to be responsive to the changes and threats available in natural habitat and we are working on evaluating this scientifically to see if the birds’ rich behavioral repertoire is being recovered now that they have been reintroduced into the forest.
Conservationists are optimistic for the future of these birds as the crows continue to adapt to their surroundings, develop predator avoidance skills, and begin to forage on native plants, but this is only the beginning. These 11 individuals are just in the first phase in the recovery of the species. So far, the successes show promise for the future.
Featured photo: ‘Alalā on a branch. Credit: San Diego Zoo Global
Source: San Diego Zoo Global and the Hawai’i Department of Land and Natural Resources Press Release
- Science has Spoken: Coral Reefs Thrive by Rat-free Islands - July 12, 2018
- Managing Invasive Species to Protect Kauai’s Native Puaiohi - July 5, 2018
- Hawaii: Extinction Capital of the World - June 29, 2018
- Insight through Seabird Flight for Black-browed Albatross - June 22, 2018
- The Invasive Rose-ringed Parakeet – a Threat from Hawai’i to Spain - May 24, 2018
- Birds and Insects Perking up on Antipodes Island after Restoration Project - May 24, 2018
- Biodiversity: What is it and Why Does it Matter? - May 17, 2018
- Palmyra Atoll – A Hope Spot for the World’s Oceans - April 27, 2018
- Scientists Study Vocalizations of Thriving, Wild ‘Alalā - April 20, 2018
- Conservation and the Future of Kaho’olawe - March 28, 2018 | <urn:uuid:f35b63d4-fe4a-4358-9c38-7a4bb1b90909> | 3.578125 | 722 | News (Org.) | Science & Tech. | 24.762898 | 95,547,520 |
+44 1803 865913
There are an estimated 40,000 species of chrysomelids, or leaf beetles, worldwide. These biologically interesting and often colorful organisms, such as the tortoise beetles, have a broad range of life histories and fascinating adaptations. For example, there are chrysomelids with shortened wings (brachypterous) and elytra (brachelytrous), other species are viviparous, and yet other leaf beetles have complicated anti predator-parasitoid defenses. Some species, such as corn rootworms (several species in the genus Diabrotica) constitute major agricultural crop pests.
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Vitrified municipal waste as a host form for high-level nuclear waste
- 197 Downloads
Preparing glass to be used as a radioactive waste immobilizer from municipal waste is the aim of this paper. Up to 90 wt% of municipal waste was obtained by burning the raw waste at 700 °C for 5 h; this were successfully vitrified into borosilicate and sodium borate glasses at ~1,200 °C. The long term behavior of such glass is one of the most important factors, which is determined by their durability in aqueous solution. Experimental durability data of the prepared glass immersed in ground water together with γ-irradiation was found to be affected according to the different irradiation doses. In addition, thermal analysis and glass surface morphology were investigated. The evolution of the damage on the studied properties was correlated to the changes in the glass network depending on their composition and irradiation dose. The results showed that glass matrix containing higher amount of municipal waste possess high durability and low thermal expansion after being gamma irradiated. The results showed that glass containing higher amount of municipal waste possess high durability and low thermal expansion after irradiation.
KeywordsGlasses Recycling Radiation Corrosion
- 14.Lemmens K, Van Iseghem P (2001) Mater Res Soc Symp Proc 663:86Google Scholar
- 18.El-Aalaily NA, Saad EA, Mahmoud HH, Ghonaim NA, Abd-Elaziz TD, Hamed E, Ezz-Eldin FM (2007) Effect of different aqueous solutions on gamma irradiated commercial and simulated soda lime silica glasses. Egypt J Chem 50(5):645–666Google Scholar
- 19.El-Aalaily NA (2003) Study of some properties of lithium silicate glass and glass ceramics containing blast furnace slag. Glass Technol 44(1):30–38Google Scholar
- 22.ElBatal HA, El-Alaily NA (2001) Thermal expansion of some gamma irradiated lead borate glasses. Nucl Sci J 38(5):314–322Google Scholar | <urn:uuid:eeb88598-6d1b-46ed-97cb-ff7879ae8363> | 2.796875 | 440 | Truncated | Science & Tech. | 39.323118 | 95,547,533 |
Uranium: the essentials
Uranium atoms have 92 electrons and the shell structure is 184.108.40.206.21.9.2. The ground state electronic configuration of neutral uranium is [Rn].5f3.6d1.7s2 and the term symbol of uranium is 5L6.
Uranium is of great interest because of its application to nuclear power and nuclear weapons. Uranium contamination is an emotive environmental problem. It is not particularly rare and is more common than beryllium or tungsten for instance.
This sample is from The Elements Collection, an attractive and safely packaged collection of the 92 naturally occurring elements that is available for sale.
Cartoon by Nick D Kim ([Science and Ink], used by permission).
Uranium gives interesting yellow and green colours and fluorescence effects when included to glass in conjunction with other additives. The image below is an English amphora dating to about 1930 showing a characteristic yellow-green colour. The image is reproduced with the permission of Ken Tomabechi (Uranium Glass Gallery in Japan), where you can find further information about uranium glass. This type of glass is sometimes referred to as "vaseline glass" in the UK and USA and as "Annagelb" (yellow) or "Annagruen" (green) in Germany.
Uranium: physical properties
Uranium: heat properties
- Melting point: 1405.3 [1132.2 °C (2070 °F)] K
- Boiling point: 1405.3 [1132.2 °C (2070 °F)] K
- Enthalpy of fusion: 20.5 kJ mol-1
Uranium: atom sizes
- Atomic radius (empirical): 175 pm
- Molecular single bond covalent radius: 170 (coordination number 3,6) ppm
- van der Waals radius: [ 305 ] ppm
- Pauling electronegativity: 1.38 (Pauling units)
- Allred Rochow electronegativity: 1.22 (Pauling units)
- Mulliken-Jaffe electronegativity: (no data)
Uranium: orbital properties
- First ionisation energy: 597.63 kJ mol‑1
- Second ionisation energy: 1120 kJ mol‑1
- Third ionisation energy: 1910 kJ mol‑1
Uranium: crystal structure
Uranium: biological data
- Human abundance by weight: 1 ppb by weight
Uranium has no biological role.
Reactions of uranium as the element with air, water, halogens, acids, and bases where known.
Uranium: binary compounds
Binary compounds with halogens (known as halides), oxygen (known as oxides), hydrogen (known as hydrides), and other compounds of uranium where known.
Uranium: compound properties
Bond strengths; lattice energies of uranium halides, hydrides, oxides (where known); and reduction potentials where known.
Uranium: historyUranium was discovered by Martin Klaproth in 1789 at Germany. Origin of name: named after "the planet Uranus".
Isolation: coming soon! | <urn:uuid:4f9e86d4-4b93-4330-8b24-cb4f11becc3e> | 3.59375 | 690 | Knowledge Article | Science & Tech. | 46.1275 | 95,547,540 |
A team of scientists has developed a way to measure magnetic fields using a quantum system, which could mean more precise technology for future sensors.
The researchers, from Aalto University in Helsinki, and MIPT and Landau Institute in Moscow, used this method to achieve accuracy beyond the standard quantum limit and thus believe that their work is a first step towards using quantum-enhanced methods for sensor technology.
They said that their research pushes the limits to how accurately you can measure things and is potentially important in a variety of fields, from geological prospecting to imaging brain activity.
"We wanted to design a highly efficient but minimally invasive measurement technique," explained Sorin Paraoanu, leader of the Kvantti research group at Aalto University.
"Imagine, for example, extremely sensitive samples: we have to either use as low intensities as possible to observe the samples or push the measurement time to a minimum."
The study, published in the prestigious journal NPJ Quantum Information shows how to improve the accuracy of magnetic field measurements by exploiting the coherence of a superconducting artificial atom, a qubit.
In their study, the scientists developed a tiny device made of overlapping strips of aluminium evaporated on a silicon chip - a technology similar to the one used to fabricate the processors of mobile phones and computers. When the device was cooled to a very low temperature, the electrical current flowed in it without any resistance and started to display quantum mechanical properties similar to those of real atoms.
When irradiated with a microwave pulse - not unlike the ones in household microwave ovens - the state of the artificial atom changed. It turns out that this change depended on the external magnetic field applied: measure the atom and you will figure out the magnetic field.
But to surpass the standard quantum limit, another trick had to be performed using a technique similar to a widely-applied branch of machine learning, pattern recognition.
"We use an adaptive technique: first, we perform a measurement, and then, depending on the result, we let our pattern recognition algorithm decide how to change a control parameter in the next step in order to achieve the fastest estimation of the magnetic field," added Andrey Lebedev, corresponding author of the study.
"'This is a nice example of quantum technology at work: by combining a quantum phenomenon with a measurement technique based on supervised machine learning, we can enhance the sensitivity of magnetic field detectors to a realm that clearly breaks the standard quantum limit."
Microsoft receives a 30 per cent cut of all purchases on the Xbox digital store
Credit card thieves used Apple ID accounts to buy and sell virtual currency for Clash of Clans and Clash Royale and Marvel Contest of Champions
$5.1bn fine further evidence that the EU is anti-US, claims Trump
New cable will connect Virginia to France | <urn:uuid:04db1d50-4b68-4d06-8737-6bd8f2f60118> | 3.53125 | 574 | News Article | Science & Tech. | 14.403443 | 95,547,569 |
|MLA Citation:||Bloomfield, Louis A. "Question 1129"|
How Everything Works 23 Jul 2018. 23 Jul 2018 <http://howeverythingworks.org/print1.php?QNum=1129>.
The blue light from the sky normally travels directly toward your eyes so that you see it coming from the sky. But when there is a layer of very hot air near the ground in the distance, some of the blue light from the sky in front of you bends upward toward your eyes. This light was traveling toward the ground in front of you at a very shallow angle but it didn't hit the ground. Instead, its entry into the hot air layer bent it upward so that it arced away from the ground and toward your eyes. When you look at the ground far in front of you, you see this deflected light from the blue sky turned up at you by the air and it looks as though it has reflected from a layer of water in front of you. This bending of light that occurs when light goes from higher-density cold air to lower-density hot air is called refraction, the same effect that bends light as light enters a camera lens or a raindrop or a glass of water. Whenever light changes speeds, it can experience refraction and light speeds up in going from cold air to hot air. In this case, the light bends upward, missing the ground and eventually reaching your eyes. | <urn:uuid:8986cc4d-e9b3-47ee-a67a-1eeebe35c85d> | 3.8125 | 293 | Knowledge Article | Science & Tech. | 80.62123 | 95,547,573 |
National Center for
1JB0: Crystal Structure of Photosystem I: a Photosynthetic Reaction Center and Core Antenna System from Cyanobacteria
Nature (2001) 411 p.909-917» All references (5)
Life on Earth depends on photosynthesis, the conversion of light energy from the Sun to chemical energy. In plants, green algae and cyanobacteria, this process is driven by the cooperation of two large protein-cofactor complexes, photosystems I and II, which are located in the thylakoid photosynthetic membranes. The crystal structure of photosystem I from the thermophilic cyanobacterium Synechococcus elongatus described here provides a picture at atomic detail of 12 protein subunits and 127 cofactors comprising 96 chlorophylls, 2 phylloquinones, 3 Fe4S4 clusters, 22 carotenoids, 4 lipids, a putative Ca2+ ion and 201 water molecules. The structural information on the proteins and cofactors and their interactions provides a basis for understanding how the high efficiency of photosystem I in light capturing and electron transfer is achieved. | <urn:uuid:05c51c1a-c047-4b4f-95ca-ca8e59f78547> | 2.53125 | 235 | Academic Writing | Science & Tech. | 12.965208 | 95,547,578 |
Tardigrade's Are DNA Master Thieves
News Nov 24, 2015
Researchers from the University of North Carolina at Chapel Hill have sequenced the genome of the nearly indestructible tardigrade, the only animal known to survive the extreme environment of outer space, and found something they never expected: that they get a huge chunk of their genome - nearly one-sixth or 17.5 percent - from foreign DNA.
"We had no idea that an animal genome could be composed of so much foreign DNA," said co-author Bob Goldstein, faculty in the biology department in UNC's College of Arts and Sciences. "We knew many animals acquire foreign genes, but we had no idea that it happens to this degree."
The work, publish today in the Proceeding of the National Academy of Sciences, not only raises the question of whether there is a connection between foreign DNA and the ability to survive extreme environments, but further stretches conventional views of how DNA is inherited.
First author Thomas Boothby, Goldstein and their collaborators revealed that tardigrades acquire about 6,000 foreign genes primarily from bacteria, but also from plants, fungi and Archaea, through a process called horizontal gene transfer - the swapping of genetic material between species as opposed to inheriting DNA exclusively from mom and dad. Previously another microscopic animal called the rotifer was the record-holder for having the most foreign DNA, but it has about half as much as the tardigrade. For comparison, most animals have less than one percent of their genome from foreign DNA.
"Animals that can survive extreme stresses may be particularly prone to acquiring foreign genes -- and bacterial genes might be better able to withstand stresses than animal ones," said Boothby, a postdoctoral fellow in Goldstein's lab. After all, bacteria have survived the Earth's most extreme environments for billions of years.
The team speculates that the DNA is getting into the genome randomly but what is being kept is what allows tardigrades to survive the harshest of environments, e.g. stick a tardigrade in a - 80 celsius freezer for a year or 10 and it starts running around in 20 minutes after thawing.
This is what the team thinks happens: when tardigrades are under conditions of extreme stress such as desiccation - or a state of extreme dryness -- Boothby and Goldstein believe that the tardigrade's DNA breaks into tiny pieces. When the cell rehydrates, the cell's membrane and nucleus, where the DNA resides, becomes temporarily leaky and DNA and other large molecules can pass through easily. Tardigrades not only can repair their own damaged DNA as the cell rehydrates but also stitch in the foreign DNA in the process, creating a mosaic of genes that come from different species.
"We think of the tree of life, with genetic material passing vertically from mom and dad," said Boothby. "But with horizontal gene transfer becoming more widely accepted and more well known, at least in certain organisms, it is beginning to change the way we think about evolution and inheritance of genetic material and the stability of genomes. So instead of thinking of the tree of life, we can think about the web of life and genetic material crossing from branch to branch. So it's exciting. We are beginning to adjust our understanding of how evolution works."
Identical Twin Study Shows Impact of a Lifetime of Exercise on FItnessNews
When it comes to being fit, are genes or lifestyle more important? Researchers removed the nature part of the equation by studying a pair of identical twins who had taken radically different fitness paths over three decades. One became an Ironman triathlete while the other remained relatively sedentary over the last 30 years.
Molecular Key for Delaying Multiple Sclerosis ProgressionNews
In work just published it was possible to identify a receptor known as P2X4 present in the microglial cells that increases their anti-inflammatory potential in order to reduce the damage in Multiple Sclerosis and, above all, encourage the body's own repair responses.READ MORE | <urn:uuid:479ed754-8297-4ba3-bc80-78210ec07745> | 3.375 | 833 | News Article | Science & Tech. | 31.267328 | 95,547,583 |
Scientists are trying to solve the mystery of these big crabs’ colorful differences. Photo Credit: John Tann
Coconut crabs (Birgus latro) are gigantic land-dwelling crabs found on islands throughout the Indo-Pacific. They can live for decades, and can grow to be more than 3 feet wide (legs outstretched) and weigh in at more than 6 pounds. So that name isn’t because they’re the size of a coconut—it’s because they can actually tear open coconuts to eat their tender meat.
“If a coconut falls out of a tree, they’ll clamp onto it on the top and then drag it back to their husking ground,” explained Victoria Morgan, a PhD Candidate in the Department of Evolution and Ecology at University of California, Davis. You can always tell where a crab hides out by the piles of coconut husks lying around.
And it just so happens that out these massive, tree-climbing crabs come in multiple colors. They start out white as juveniles, when they act like other hermit crabs and don a protective shell. Then, as they mature and grow, they turn either red or blue. Really, really red, and really, really blue. “It’s weird that the colors are so distinctive,” Morgan explained. Stark color differences within a species, or color polymorphisms as scientists call them, are found in other crab species, but they’re generally in young animals.
Coconut crabs come in strikingly different colors, but scientists can’t seem to figure out why. Photo by Brocken Inaglory
You’d think that kind of striking color difference arose for some evolutionary reason. Luckily, that’s just the sort of colorful mystery that fascinates Tim Caro, evolutionary ecologist at UC Davis. So he asked Morgan — who was studying other land crabs at the time — to help him uncover what’s going on.
“We wanted to test some of the more traditional explanations for different colors in nature,” said Morgan. Lots of species have different colors due to sexual selection, for example, as different male and female colors can happen if females are choosy about their mate’s looks or if males compete. Or it could be a simple size thing, like if shell thickness leads to one color (which is essentially what happens in the shore crab Carcinus maenas). Or the colors could provide unique advantages in different environments, like is the case with pepper moths.
So to tease apart the different possible explanations, the duo went to three different locations—the Pemba Island archipelago and Chumbe Island off Tanzania, and Christmas Island, an Australian territory south of Indonesia—and collected 325 crabs. For each, they recorded sex and took all sorts of physical measurements of the animals, including how strong they could pinch. They also when and where each was found. And they even did a quick crab personality test by noting their “disposition to being handled on a 5-point subjective docility scale”—which, for the record, goes from being shy and still to “aggressive (repeatedly grasps the holding bucket and rapidly extends abdomen)”.
The dynamic duo in the field. Top L: a red coconut crab. Top R: Tim Caro testing a crab’s pinch. Bottom L: Victoria Morgan weighing a crab. Bottom R: a blue coconut crab. All photos credited to Tim Caro except the bottom left, which is courtesy of Victoria Morgan.
On each of the islands, between two thirds and three quarters of the crabs were red. Most of the crabs were males in general, but there was no correlation between color and sex. There were also no correlations to weight or other measurements of size. And there was no correlation between pinching ability and color, either. They did find that bigger crabs were more docile (which, when you’re talking about a >6 lb crab, is probably a good thing)—but color didn’t matter at all. The only slight hint they found was that the blue crabs seemed to be more common near the ocean while the red ones more common inland, but the association wasn’t significant.
“What we found to be most surprising was that none of the traditional hypotheses explain this system,” Morgan said, laughing. In a couple weeks, though, Morgan and Caro are headed back to Tanzania. They hope to up the sample number to see if the habitat difference becomes significant, and to try some new ideas.
They want to observe them mating, for example, to determine if the different colors seem to prefer mating with one of their own. And they really want to look at the crabs’ DNA. “The first step is to figure out what gene is responsible for the coloring in these crabs,” she explained. The team has a hunch that it might have something to do with the expression of a protein called crustacyanin (which is how blue lobsters get their smurfy hue). In addition, they want to look at the expression of genes in the crabs’ eyes to determine whether they can even see the two colors. Some crustaceans have excellent color vision (like mantis shrimps), but that may not be the case with the coconut crab. They’ll also look at the crabs’ genomes to get a better idea of how often the two color morphs are interbreeding (especially if they don’t find too many mating pairs).
Oh big crab, why are you so blue? Photo Credit: David Stanley
There has to be something keeping both colors around, Morgan said — otherwise, over time, one would just disappear. “You’d expect that it’d swing one way or the other, so that you’d end up with all red crabs or all blue crabs,” she said. “The fact that we see both morphs across the different parts of their range indicates there’s something that’s driving them to keep the polymorphisms present in their population —we just haven’t figured it out yet.”
In the meantime, these weird, colorful crabs will continue to eek out their existence on the islands in the Indo-Pacific, chowing on their coconuts and… well, actually, about that.
They’re not just coconut-eaters. “They tend to eat everything,” Morgan explained. She’s even seen them digging through trash bins. “And their sense of smell is amazing. Whenever I was cooking on the island, they’d come from all over the island to try to eat what I was eating,” she said. They’d even try to scale the gate of her kitchen area to get a taste, which she admitted was “a little creepy.” And they often eat at night, so, they’re basically the crustacean version of a raccoon.
In fact, just last year, biologists confirmed that they not only will eat pretty much whatever, including carrion if they find it, they can climb trees and kill full-grown birds — snapping a brittle booby bone is apparently easy for those powerful claws.
But despite their infamous taste for flesh,”they usually keep to themselves,” Morgan explained. It’s not like they’re chasing after you — they usually just kind of meander around slowly, “and they typically try to escape when approached by humans,” she noted. “I don’t want people to think that they’re a real threat to human safety.”
In fact, it’s the crabs’ safety that’s threatened if anything. “It’s very likely that they’re actually an endangered species due to population pressures from human consumption,” said Morgan (they’re “data-deficient” according to the latest IUCN update, but their populations are likely declining). These slow-growing crabs take at least 5 years to reach maturity, several decades to become fully grown, and can live almost as long as we do. And that means they’re just not great at rebounding if their numbers crash. So if we keep messing with these amazing animals the way we are now by eating them and destroying their island homes, we may never understand their colorful lives.
— Jake Buehler (@buehlersciwri) September 1, 2015
Citation: Caro & Morgan, 2018. Correlates of color polymorphism in coconut crabs Birgus latro. Zoology 129: 1-8. doi:10.1016/j.zool.2018.06.002 | <urn:uuid:94811d5b-2258-4468-bc1f-9f17557361b0> | 3.921875 | 1,843 | Truncated | Science & Tech. | 57.299411 | 95,547,592 |
GENEVA, July 10 (Xinhua) -- Globally, this June marks the second warmest on record and this year to date the hottest La Nina year on record, which has been featured by high impacting extreme weather during the early summer in the northern hemisphere, the World Meteorological Organization (WMO)said on Tuesday.
Temperatures were not only exceptionally high over large parts of northern Siberia in June, but also well above average over much of the United States, central Canada and North Africa, and over the Middle East.
The WMO said although it is not possible to attribute the individual extreme events of June and July to climate change, they are compatible with the general long-term trend due to rising concentrations of greenhouse gases.
As a result, episodes of extreme heat and precipitation are increasing around the globe. For example, Japan has suffered the worst flooding and landslide in decades, with many daily rainfall records broken.
Between June 28 and July 8, there was extraordinary heavy rainfall caused by huge amount of water vapor provided by a stationary rainy front in addition to damp air remaining from Typhoon Prapiroon. West Japan and Hokkaido experienced record precipitation during the period, according to the Japan Meteorological Agency.
Meanwhile, extreme and unusual temperatures have been recorded around the world. On June 28, Quriyat, just south of Muscat, on the coast of Oman, recorded a 24-hour minimum temperature of 42.6 degrees Celsius, meaning that the coolest overnight temperature did not drop below.
According to the WMO, many recent studies have found that the probability of the extreme event has been influenced by human activity, either directly or indirectly.
Of a set of 131 studies published between 2011 and 2016 in the Bulletin of the American Meteorological Society, 65 percent found that the event's probability was significantly affected by anthropogenic activities, the WMO said. | <urn:uuid:770840b9-79ef-4d57-aa07-307b64636021> | 3.125 | 382 | News Article | Science & Tech. | 23.149005 | 95,547,594 |
SLAC and Stanford researchers demonstrate that brain-mimicking ‘neural networks’ can revolutionize the way astrophysicists analyze their most complex data, including extreme distortions in spacetime that are crucial for our understanding of the universe.
Researchers from the Department of Energy’s SLAC National Accelerator Laboratory and Stanford University have for the first time shown that neural networks – a form of artificial intelligence – can accurately analyze the complex distortions in spacetime known as gravitational lenses 10 million times faster than traditional methods.
“Analyses that typically take weeks to months to complete, that require the input of experts and that are computationally demanding, can be done by neural nets within a fraction of a second, in a fully automated way and, in principle, on a cell phone’s computer chip,” said postdoctoral fellow Laurence Perreault Levasseur, a co-author of a study published today in Nature.
Lightning Fast Complex Analysis
The team at the Kavli Institute for Particle Astrophysics and Cosmology (KIPAC), a joint institute of SLAC and Stanford, used neural networks to analyze images of strong gravitational lensing, where the image of a faraway galaxy is multiplied and distorted into rings and arcs by the gravity of a massive object, such as a galaxy cluster, that’s closer to us. The distortions provide important clues about how mass is distributed in space and how that distribution changes over time – properties linked to invisible dark matter that makes up 85 percent of all matter in the universe and to dark energy that’s accelerating the expansion of the universe.
Until now this type of analysis has been a tedious process that involves comparing actual images of lenses with a large number of computer simulations of mathematical lensing models. This can take weeks to months for a single lens.
But with the neural networks, the researchers were able to do the same analysis in a few seconds, which they demonstrated using real images from NASA’s Hubble Space Telescope and simulated ones.
To train the neural networks in what to look for, the researchers showed them about half a million simulated images of gravitational lenses for about a day. Once trained, the networks were able to analyze new lenses almost instantaneously with a precision that was comparable to traditional analysis methods. In a separate paper, submitted to The Astrophysical Journal Letters, the team reports how these networks can also determine the uncertainties of their analyses.
KIPAC researcher Phil Marshall explains the optical principles of gravitational lensing using a wineglass. (Brad Plummer/SLAC National Accelerator Laboratory)
Prepared for Data Floods of the Future
“The neural networks we tested – three publicly available neural nets and one that we developed ourselves – were able to determine the properties of each lens, including how its mass was distributed and how much it magnified the image of the background galaxy,” said the study’s lead author Yashar Hezaveh, a NASA Hubble postdoctoral fellow at KIPAC.
This goes far beyond recent applications of neural networks in astrophysics, which were limited to solving classification problems, such as determining whether an image shows a gravitational lens or not.
The ability to sift through large amounts of data and perform complex analyses very quickly and in a fully automated fashion could transform astrophysics in a way that is much needed for future sky surveys that will look deeper into the universe – and produce more data – than ever before.
The Large Synoptic Survey Telescope (LSST), for example, whose 3.2-gigapixel camera is currently under construction at SLAC, will provide unparalleled views of the universe and is expected to increase the number of known strong gravitational lenses from a few hundred today to tens of thousands.
“We won’t have enough people to analyze all these data in a timely manner with the traditional methods,” Perreault Levasseur said. “Neural networks will help us identify interesting objects and analyze them quickly. This will give us more time to ask the right questions about the universe.”
KIPAC researchers used images of strongly lensed galaxies taken with the Hubble Space Telescope to test the performance of neural networks, which promise to speed up complex astrophysical analyses tremendously. (Yashar Hezaveh/Laurence Perreault Levasseur/Phil Marshall/Stanford/SLAC National Accelerator Laboratory; NASA/ESA)
A Revolutionary Approach
Neural networks are inspired by the architecture of the human brain, in which a dense network of neurons quickly processes and analyzes information.
In the artificial version, the “neurons” are single computational units that are associated with the pixels of the image being analyzed. The neurons are organized into layers, up to hundreds of layers deep. Each layer searches for features in the image. Once the first layer has found a certain feature, it transmits the information to the next layer, which then searches for another feature within that feature, and so on.
“The amazing thing is that neural networks learn by themselves what features to look for,” said KIPAC staff scientist Phil Marshall, a co-author of the paper. “This is comparable to the way small children learn to recognize objects. You don’t tell them exactly what a dog is; you just show them pictures of dogs.”
But in this case, Hezaveh said, “It’s as if they not only picked photos of dogs from a pile of photos, but also returned information about the dogs’ weight, height and age.”
Scheme of an artificial neural network, with individual computational units organized into hundreds of layers. Each layer searches for certain features in the input image (at left). The last layer provides the result of the analysis. The researchers used particular kinds of neural networks, called convolutional neural networks, in which individual computational units (neurons, gray spheres) of each layer are also organized into 2-D slabs that bundle information about the original image into larger computational units. (Greg Stewart/SLAC National Accelerator Laboratory)
Although the KIPAC scientists ran their tests on the Sherlock high-performance computing cluster at the Stanford Research Computing Center, they could have done their computations on a laptop or even on a cell phone, they said. In fact, one of the neural networks they tested was designed to work on iPhones.
“Neural nets have been applied to astrophysical problems in the past with mixed outcomes,” said KIPAC faculty member Roger Blandford, who was not a co-author on the paper. “But new algorithms combined with modern graphics processing units, or GPUs, can produce extremely fast and reliable results, as the gravitational lens problem tackled in this paper dramatically demonstrates. There is considerable optimism that this will become the approach of choice for many more data processing and analysis problems in astrophysics and other fields.”
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"The first nervous systems appeared in jellyfish-like animals six hundred million years ago or so," says Harold Zakon, professor of neurobiology, "and it was thought that sodium channels evolved around that time. We have now discovered that sodium channels were around well before nervous systems evolved."
Zakon and his coauthors, Professor David Hillis and graduate student Benjamin Liebeskind, published their findings this week in PNAS.
Nervous systems and their component neuron cells were a key innovation in the evolution of animals, allowing for communication across vast distances between cells in the body and leading to sensory perception, behavior and the evolution of complex animal brains.
Sodium channels are an integral part of a neuron's complex machinery. The channels are like floodgates lodged throughout a neuron's levee-like cellular membrane. When the channels open, sodium floods through the membrane into the neuron, and this generates nerve impulses.
Zakon, Hillis and Liebeskind discovered the genes for such sodium channels hiding within an organism that isn't even made of multiple cells, much less any neurons. The single-celled organism is a choanoflagellate, and it is distantly related to multi-cellular animals such as jellyfish and humans.
The researchers then constructed evolutionary trees, or phylogenies, showing the relationship of those genes in the single-celled choanoflagellate to multi-cellular animals, including jellyfish, sponges, flies and humans.
Because the sodium channel genes were found in choanoflagellates, the scientists propose that the genes originated not only before the advent of the nervous system, but even before the evolution of multicellularity itself.
"These genes were then co-opted by the nervous systems evolving in multi-cellular animals," says Hillis, the Alfred W. Roark Centennial Professor in Natural Sciences. "This study shows how complex traits, such as the nervous system, can evolve gradually, often from parts that evolved for other purposes."
"Evolutionarily novel organs do not spring up from nowhere," adds Zakon, "but from pre-existing genes that were likely doing something else previously."
Liebeskind, a graduate student in the university's ecology, evolution and behavior program, is directing his next research efforts toward understanding what the sodium channels do in choanoflagellates.
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Dispersion of Light Multiple Choice Questions 17 PDF Download
Practice dispersion of light MCQs, grade 7 science test 17 for online courses learning and test prep, primary colored lights multiple choice questions and answers. Primary colored lights revision test includes science worksheets to learn.
Science multiple choice questions (MCQ) on if red, green and blue are mixed together, formed color of light will be with options violet, blue, indigo and white, primary colored lights quiz for competitive exam prep, viva interview questions with answers key. Free science study guide to learn primary colored lights quiz to attempt multiple choice questions based test.
MCQs on Dispersion of Light Quiz PDF Download Worksheets 17
MCQ. If red, green and blue are mixed together, the formed color of light will be
MCQ. Like sound, light travels as a
MCQ. The scientist who presented the theory of dispersion of light was
MCQ. The dispersion of white light into seven different colors is known as
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MCQ. The index that identifies each object is known as
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Please help with the following problem. Provide step by step calculations.
Tsunamis are fast-moving waves generated by underwater earthquakes. In the deep ocean their amplitude is barely noticeable, but upon reaching the shore, they can rise up to the astonishing height of a six-story building. One tsunami, generated off the Aleutian islands in Alaska, had a wave length of 650 km and traveled a distance of 3700 km in 5.6 h.
(a) What was the speed (in m/s) of the wave? For reference, the speed of a 747 jetliner is about 250 m/s.
(b) Find the wave's frequency.
(c) Find the wave's period.© BrainMass Inc. brainmass.com July 18, 2018, 4:30 pm ad1c9bdddf
Following is the text part of the solution. Please see the attached file for complete solution. Equations, diagrams, graphs and special characters will not appear correctly here. Thank you for using ...
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Since Tropical Storm Karina weakened from hurricane status, and since then, NASA satellite data has shown that the storm has been pretty consistent with strength and thunderstorm development.
Hurricane Karina formed on August 13, 2014 off the Mexican coast. The Tropical Rainfall Measuring Mission or TRMM satellite passed directly above the center of intensifying tropical storm Karina on August 14, 2014 at 1927 UTC (3:27 p.m. EDT).
NASA's Aqua satellite passed over Tropical Storm Karina on August 18 at 6:23 a.m. EDT on Monday, August 18 and the AIRS instrument captured an infrared image. The image showed strong thunderstorms (purple) continued to circle the center.
Credit: NASA JPL/Ed Olsen
TRMM's Microwave Imager showed that storms near Karina's center were dropping rain at a rate of over 50mm (almost 2 inches) per hour. After that TRMM fly over, Karina was upgraded to a hurricane within a couple hours. However, in less than 24 hours, by August 15 at 5 a.m. EDT (0900 UTC), Karina weakened back to tropical storm status.
In the days that followed, Karina's cloud pattern didn't change much. Satellite data showed that strong thunderstorms still circle the center, especially on the northern edge.
NASA's Aqua satellite passed over Tropical Storm Karina on August 18 at 6:23 a.m. EDT on Monday, August 18 and the Atmospheric Infrared Sounder or AIRS instrument captured infrared data on the storm's clouds.
Infrared data basically shows temperature, and the AIRS data showed strong thunderstorms with cloud top temperatures near -63F/-52C indicating they were high in the troposphere. The bulk of the strong thunderstorms continued to be pushed to the northern quadrant as a result of southerly wind shear.
At 11 a.m. EDT (1500 UTC) Karina's maximum sustained winds remain near 45 mph (75 kph). The center of Tropical Storm Karina was located near latitude 16.8 north and longitude 132.4 west, that's about 1,500 miles (2,415 km) east of Hilo, Hawaii.
Karina is moving toward the west-southwest near 9 mph (15 kph) and is expected to slow down. The estimated minimum central pressure is 1002 millibars.
NHC's forecaster Avila noted that "Karina has the chance to slightly strengthen since the circulation is moving over warmer waters and into weaker shear. By the end of the forecast period, the outflow from larger Tropical Depression 12-E to the northeast should induce stronger shear and prevent additional strengthening."
Text credit: Rob Gutro
NASA's Goddard Space Flight Center
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行動版 - 2013年6月5日 - Because before starting to learn Java programming, you need to prepare your machine. ... To write and test the Java codes, you need to install Java's software development kit (JDK).
Programming Exercises for beginning Java developersjava.about.com
Programming Exercises for beginning Java developers to test their knowledge of Java syntax ... In order to be able to put the knowledge you learn from the Java articles it's important to put into practice your newly found Java skills.
Beginning Java Programming: The Object-Oriented Approach by Bart Baesens, Aimee Backiel, Seppe vandewww.barnesandnoble.com
Comprehensive guide for learning Java and applying it in the real world This unique guide goes beyond teaching you the basics of the Java programming language by also showing you how to apply Java, whether for your own Android projects or in the workplace
A Beginning Programmer's Guide to Javabeginwithjava.blogspot.com
You can program in Java (or are learning to.) That's great! But what else can you do with those skills? Are you trapped with Java? Not at all. One of the reasons I chose Java as a language for use in the classroom is that Java programming skills translate
The NEWEST Hoop De Loop Saga Complete Guide! Master the game today! With Tips, Tricks, Videos, How to Play, and MORE! This is the BEST GUIDE for any H... | <urn:uuid:8d9786f5-8f38-47c3-b29c-e607c8e5e541> | 2.921875 | 897 | Content Listing | Software Dev. | 51.468153 | 95,547,644 |
The whale bones are now being examined by researchers at the University of Gothenburg who, among other things, want to ascertain whether the find is the mystical "Swedenborg whale".
Similar to the "Swedenborg whale"
There are currently four species of right whale. What is particularly interesting is that the size and shape of the whale bones resemble those of a fifth species: the mystical "Swedenborg whale", first described by the scientist Emmanuel Swedenborg in the 18th century.
-Bones from what is believed to be Swedenborg's right whale have previously been found in western Sweden. However, determining the species of whale bones found in earth is complicated and there is no definitive conclusion on whether the whale actually existed, it could equally well be a myth, says zoologist Thomas Dahlgren and his colleague Leif Jonsson.DNA tests conducted
- The hunt for the large whale species, which led to the extinction of the Atlantic grey whale and perhaps the Swedenborg whale, may also have caused the extinction of a large number of species that are dependent on whale carcasses for their survival, says Thomas Dahlgren.Preserved in clay
46 (0)703-662042Facts about the Swedenborg whale (Balaena swedenbo´rgii)
Helena Aaberg | idw
Global study of world's beaches shows threat to protected areas
19.07.2018 | NASA/Goddard Space Flight Center
NSF-supported researchers to present new results on hurricanes and other extreme events
19.07.2018 | National Science Foundation
A new manufacturing technique uses a process similar to newspaper printing to form smoother and more flexible metals for making ultrafast electronic devices.
The low-cost process, developed by Purdue University researchers, combines tools already used in industry for manufacturing metals on a large scale, but uses...
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
20.07.2018 | Power and Electrical Engineering
20.07.2018 | Information Technology
20.07.2018 | Materials Sciences | <urn:uuid:aaa38732-25cd-4f3f-837f-b4271a808e1c> | 3.515625 | 841 | Content Listing | Science & Tech. | 38.928193 | 95,547,679 |
Using a cosmic magnifying-glass effect, NASA's Hubble Space Telescope has captured unique close-up views of the brightest infrared galaxies in the universe which are as much as 10,000 times more luminous than the Milky Way. The cosmic magnifying effect, a phenomenon called gravitational lensing, occurs when the intense gravity of a massive galaxy or cluster of galaxies magnifies the light of fainter, more distant background sources.
The galaxy images revealed a tangled web of misshapen objects punctuated by exotic patterns such as rings and arcs. The odd shapes are due largely to the foreground lensing galaxies' powerful gravity distorting the images of the background galaxies. The unusual forms also may have been produced by spectacular collisions between distant, massive galaxies in a sort of cosmic demolition derby, the researchers observed.
"We have hit the jackpot of gravitational lenses," said lead researcher James Lowenthal of Smith College in Massachusetts, US. "These ultra-luminous galaxies are very rare. Gravitational lensing magnifies them so that you can see small details that otherwise are unimaginable. We want to understand what's powering these monsters, and gravitational lensing allows us to study them," he added.
The results were presented at the American Astronomical Society meeting in Austin, Texas. The galaxies are ablaze with runaway star formation, pumping out more than 10,000 new stars a year. This unusually rapid star birth occurred at the peak of the universe's star-making boom more than 8 billion years ago, the light from which we are observing now. The star-birth frenzy creates lots of dust, which enshrouds the galaxies, making them too faint to detect in visible light. But they glow fiercely in infrared light, shining with the brilliance of 10 trillion to 100 trillion suns, the researchers noted.
According to researchers, there are only a few dozen of these bright infrared galaxies exist in the universe, scattered across the sky, which may hold clues to how galaxies formed billions of years ago. | <urn:uuid:1aaf12a6-c14c-4b6d-8289-1a633e83aafe> | 3.75 | 406 | News Article | Science & Tech. | 33.63975 | 95,547,713 |
The dispersant used to remediate the 2010 Deepwater Horizon oil spill in the Gulf of Mexico is more toxic to cold-water corals than the spilled oil, according to a study conducted at Temple University. The study comes on the eve of the spill’s fifth anniversary, April 20th.
In this collaborative study between researchers from Temple and the Pennsylvania State University, the researchers exposed three cold-water coral species from the Gulf to various concentrations of the dispersant and oil from the Deepwater Horizon well. They found that the dispersant is toxic to the corals at lower concentrations than the oil.
The researchers’ findings, “Response of deep-water corals to oil and chemical dispersant exposure,” were published online in the journal Deep-Sea Research II.
Approximately five million barrels of crude oil escaped from the well drilled by the Deepwater Horizon oil rig in 2010, and nearly seven million liters of dispersants—chemical emulsifiers used to break down the oil—were used to clean it up. Normally applied to the water’s surface, the spill marked the first time that dispersants were applied at depth during an oil spill.
“Applying the dispersants at depth was a grand experiment being conducted in real-time,” said Erik Cordes, associate professor of biology at Temple, who has been studying Gulf of Mexico coral communities for more than a decade. “It was a desire to immediately do something about the oil coming out of the well, but they really didn’t know what was going to happen as a result.”
Following the 2010 spill, Cordes and his collaborators discovered several damaged Gulf coral populations that were coated with a dark colored flocculent slime that was found to contain oil from the spill and residues from the dispersants.
“We wanted to know if the damages that had been witnessed could have been caused by the oil, the dispersant itself, or a combination of both,” said Danielle DeLeo, a Temple doctoral student in Cordes’ lab, who was the study’s lead author. “We know that the corals in the Gulf were exposed to all of these different combinations, so we have been trying to determine the toxicity of the oil and the dispersants, and see what their impact would be on the corals.”
The researchers exposed the corals to a range of concentrations for both the dispersant and the oil to determine a lethal dose for each. They were surprised to find that the lethal concentration is much lower for the dispersant, meaning it is more toxic than the oil.
“It doesn’t take as much dispersant to kill a coral as it does oil,” Cordes said, adding that the oil in combination with the dispersant increases the toxicity of the oil.
Using dispersants is supposed to reduce the impact of oil spills on the environment, said Cordes, “but there’s increasing evidence that’s not what’s happening.”
Cordes said that his lab will be carrying out additional studies to try to replicate the concentrations of oil and dispersant that the corals were exposed to during the Gulf oil spill, but this is the first step in determining the toxic levels of dispersants and their impact on the environment. He said their findings could assist in developing future strategies for applying dispersants at oil spills that may be more helpful than harmful to the environment.
In addition to Cordes and DeLeo, the researchers included Iliana Baums and Dannise Ruiz-Ramos of Penn State. The study was funded by a grant from the Gulf of Mexico Research Initiative to the “Ecosystem Impacts of Oil and Gas Inputs to the Gulf” consortium.
Note: Copies of the study, as well as high-res images, are available to working journalists. E-mail email@example.com.
Preston Moretz | newswise
Upcycling of PET Bottles: New Ideas for Resource Cycles in Germany
25.06.2018 | Fraunhofer-Institut für Betriebsfestigkeit und Systemzuverlässigkeit LBF
Dry landscapes can increase disease transmission
20.06.2018 | Forschungsverbund Berlin e.V.
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:89c31d5d-0811-4971-b913-731620e2f126> | 2.984375 | 1,421 | Content Listing | Science & Tech. | 43.427358 | 95,547,714 |
- Happy future physicists
- Researchers First Reveal the Behaviors of Photons in a Birefringent Interferometer
- Direct measurement of the winding number in quantum walks
- Scientists Observe Stronger-than-Binary Correlations with Entangled Photonic Qutrits
- USTC develops all-optically controlled non-reciprocal multifunctional photonic devices
Direct measurement of topological numbers with quantum simulation technology
Recently, the experimental group led by Prof. Jiangfeng Du at USTC and the theoretical collaborator Prof. Liang Jiang at Yale University have directly measured topological numbers for the first time using spins in diamond as a quantum simulator. The research results have been published in "Physical Review Letters" (Phys. Rev. Lett. 117, 060503 (2016)) in the form of “Editors’ suggestion” in August 4.
Topological numbers can characterize the transition between different topological phases, which are not described by Landau's paradigm of symmetry breaking. Since the discovery of quantum Hall effect, more topological phases have been theoretically predicted and experimentally verified. However, it is still an experimental challenge to directly measure the topological number of various predicted topological phases. Most topological systems are hardly to prepare experimentally now. While a feasible way to investigate this systems is simulating them with a controllable quantum system. If the Hamiltonian of the quantum simulator is modulated completely same with the Hamiltonian of the topological system, all the information of the topological system can be extract from the quantum simulator.
It has been reported that researchers have successfully measured the topological Chern number of different topological phases using superconducting circuits. However, their measurement of Chern number requires integration over continuous parameter space, which may not give an exactly discretized topological number. Different from their integration approach, here Prof. Jiangfeng Du and his collaborators use a single NV center in natural diamond to simulate a topological system. With well-designed microwave and radiofrequency, they have reconstructed the Hamiltonian of the topological system in different phases and measured the topological numbers precisely, which enables direct observation of the topological phase transition. (See the figure below)
Schematic diagram of the diamond quantum simulator and main experimental results
With reliable control of multiple spins of the NV center, more complicated topological systems can be simulated. Utilizing entanglement can lead to a scalable quantum simulator of NV centers. Therefore, the NV-center-based quantum simulator is a very promising platform, which will provide a powerful tool to investigate novel quantum system. Comparing with quantum computers, quantum simulators are more likely to be practically used in the near future. For some complicated materials, there exist challenges to experimentally prepare them or calculate them with classical computers. Then using a quantum simulator to investigate them has great practical significance.
Besides, the group led by Prof. Jiangfeng Du has used the similar quantum control technology to verify the Heisenberg’s measurement uncertainty relation based on statistical distances. The research results have also been published in "Physical Review Letters" (Phys. Rev. Lett. 116, 160405 (2016)). The world famous news website Phys.org has reported it, “the work provides a deeper understanding of Heisenberg's original idea about the uncertainty principle, and could also have practical applications.”
The above researches are supported by the National Natural Science Foundation of China, the Ministry of Science and Technology of China and the Chinese Academy of Sciences.
(KONG Fei,School of Physical Sciences) | <urn:uuid:5f323a34-99cf-421b-b640-c3c3a92460d4> | 2.734375 | 739 | News (Org.) | Science & Tech. | 10.745177 | 95,547,716 |
doi:10.1038/nindia.2018.49 Published online 30 April 2018
Physicists have developed a technique that employs extremely tiny light pulses to track and record electron movement in ultrafast processes such as chemical reactions – a significant step towards unveiling the secrets of ultrafast natural processes such as photosynthesis1.
Extremely tiny light pulses are used to study electron movement in atoms, molecules and transparent solids. However, it is difficult to gain insights into complex molecular systems.
Scientists from the Indian Institute of Technology Bombay, in Mumbai, India, led by Gopal Dixit, created ultra-small light pulses of extreme ultraviolet light and shone it on to a target of a known material. Each pulse lasts for an attosecond, which equals to a millionth of a trillionth of a second.
The incidence of a first light pulse ionised the target, making it emit a photoelectron. A second light pulse then tracked and recorded the electron emission and light-induced ionisation.
The light pulses, lasting for attoseconds, can play the role of a camera by recording fast-happening chemical transformations in natural processes such as vision and photosynthesis. This can help make ultrafast movies of such natural processes.
Each of life’s molecular building blocks, such as sugars and amino acids, has a twin – not an identical one, but a mirror image. In other words, there are both left- and right-handed amino acids and sugars in nature. The attosecond light pulses can be very useful for identifying such handedness of biological molecules such as DNA and carbohydrates, says lead researcher Dixit.
1. Jiménez-Galán, A. et al. Attosecond recorder of the polarization state of light. Nature. Communications. 9, 850 (2018) | <urn:uuid:6d1df3fe-9863-4049-9159-4a4ba9a3c728> | 4.15625 | 377 | Truncated | Science & Tech. | 39.109844 | 95,547,722 |
Species Detail - Tree Slug (Lehmannia marginata) - Species information displayed is based on the dataset "All Ireland Non-Marine Molluscan Database".
Terrestrial Map - 10kmDistribution of the number of records recorded within each 10km grid square (ITM).
Marine Map - 50kmDistribution of the number of records recorded within each 50km grid square (WGS84).
(O. F. Müller, 1774)
1 January (recorded in 1975)
31 December (recorded in 1973)
Conchological Society of Great Britain and Ireland, All Ireland Non-Marine Molluscan Database, National Biodiversity Data Centre, Ireland, Tree Slug (Lehmannia marginata), accessed 16 July 2018, <https://maps.biodiversityireland.ie/Dataset/1/Species/123887> | <urn:uuid:7d62e560-2ad0-4f3f-9b7b-1da2fdc8bd11> | 2.765625 | 188 | Structured Data | Science & Tech. | 34.647449 | 95,547,728 |
But in a warming world, winter and spring snow cover in the Northern Hemisphere is in decline, putting at risk many plants and animals that depend on the space beneath the snow to survive the blustery chill of winter.
In a report published May 2 in the journal Frontiers in Ecology and the Environment, a team of scientists from the University of Wisconsin-Madison describes the gradual decay of the Northern Hemisphere's "subnivium," the term scientists use to describe the seasonal microenvironment beneath the snow, a habitat where life from microbes to bears take full advantage of warmer temperatures, near constant humidity and the absence of wind.
"Underneath that homogenous blanket of snow is an incredibly stable refuge where the vast majority of organisms persist through the winter," explains Jonathan Pauli, a UW-Madison professor of forest and wildlife ecology and a co-author of the new report. "The snow holds in heat radiating from the ground, plants photosynthesize, and it's a haven for insects, reptiles, amphibians and many other organisms."
Since 1970, snow cover in the Northern Hemisphere — the part of the world that contains the largest land masses affected by snow — has diminished by as much as 3.2 million square kilometers during the critical spring months of March and April. Maximum snow cover has shifted from February to January and spring melt has accelerated by almost two weeks, according to Pauli and his colleagues, Benjamin Zuckerberg and Warren Porter, also of UW-Madison, and John P. Whiteman of the University of Wyoming in Laramie.
"The winter ecology of Wisconsin and the Upper Midwest is changing," says Zuckerberg, a UW-Madison professor of forest and wildlife ecology. "There is concern these winter ecosystems could change dramatically over the next several years."
As is true for ecosystem changes anywhere, a decaying subnivium would have far-reaching consequences. Reptiles and amphibians, which can survive being frozen solid, are put at risk when temperatures fluctuate, bringing them prematurely out of their winter torpor only to be lashed by late spring storms or big drops in temperature. Insects also undergo phases of freeze tolerance and the migrating birds that depend on invertebrates as a food staple may find the cupboard bare when the protective snow cover goes missing.
"There are thresholds beyond which some organisms just won't be able to make a living," says Pauli. "The subnivium provides a stable environment, but it is also extremely delicate. Once that snow melts, things can change radically."
For example, plants exposed directly to cold temperatures and more frequent freeze-thaw cycles can suffer tissue damage both below and above ground, resulting in higher plant mortality, delayed flowering and reduced biomass. Voles and shrews, two animals that thrive in networks of tunnels in the subnivium, would experience not only a loss of their snowy refuge, but also greater metabolic demands to cope with more frequent and severe exposure to the elements.
The greatest effects on the subnivium, according to Zuckerberg, will occur on the margins of the Earth's terrestrial cryosphere, the parts of the world that get cold enough to support snow and ice, whether seasonally or year-round. "The effects will be especially profound along the trailing edge of the cryosphere in regions that experience significant, but seasonal snow cover," the Wisconsin scientists assert in their report. "Decay of the subnivium will affect species differently, but be especially consequential for those that lack the plasticity to cope with the loss of the subnivium or that possess insufficient dispersal power to track the retreating range boundary of the subnivium."
As an ecological niche, the subnivium has been little studied. However, as snow cover retreats in a warming world, land managers, the Wisconsin researchers argue, need to begin to pay attention to the changes and the resulting loss of habitat for a big range of plants and animals.
"Snow cover is becoming shorter, thinner and less predictable," says Pauli. "We're seeing a trend. The subnivium is in retreat."
—Terry Devitt, 608-262-8282, firstname.lastname@example.org
Jonathan Pauli | EurekAlert!
Upcycling of PET Bottles: New Ideas for Resource Cycles in Germany
25.06.2018 | Fraunhofer-Institut für Betriebsfestigkeit und Systemzuverlässigkeit LBF
Dry landscapes can increase disease transmission
20.06.2018 | Forschungsverbund Berlin e.V.
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
18.07.2018 | Materials Sciences
18.07.2018 | Life Sciences
18.07.2018 | Health and Medicine | <urn:uuid:e2e8b5c6-7c43-463f-91ad-f574cceb6211> | 3.796875 | 1,523 | Content Listing | Science & Tech. | 39.622265 | 95,547,757 |
The research group at the Department of Molecular Evolution at the Evolutionary Biology Center (EBC) at Uppsala University has identified a completely new cell division machinery.
The discovery was made in Sulfolobus acidocaldarius, a microorganism belonging to the third domain of life, the Archaea, which originally was isolated from a hot spring in Yellowstone national park in Wyoming, USA. Because of the extreme conditions, in which the cells grow optimally in acid at 80ºC, the organism is of interest for a wide range of issues.
- They represent exciting model systems in theories for how life once may have originated in hot environments on early Earth, as well as in the search for life in extreme environments on other planets, professor Rolf Bernander explains. He is the scientist behind the study, together with colleagues Ann-Christin Lindås, Erik Karlsson, Maria Lindgren and Thijs Ettema.
The researchers have identified three genes that are activated just prior to cell division. The protein products from these genes form a sharp band in the middle of the cell, between newly segregated chromosomes, and then gradually constrict the cell such that two new daughter cells are formed.
- This is the first time in decades that a novel cell division mechanism has been discovered, and the gene products display no similarity to previously known division proteins, Rolf Bernander says.
Two of the three proteins are instead related to eukaryotic so-called ESCRT- proteins, which play important roles in vesicle formation during intracellular transport processes, and which also have been implicated in virus budding, including HIV, from the cell surface. The results are, thus, important not only for an increased understanding of the cell biology of archaea and extremophiles, but also for key cellular processes in human and other higher organisms, and for issues related to the origin and evolutionary history of these processes.
Anneli Waara | alfa
NYSCF researchers develop novel bioengineering technique for personalized bone grafts
18.07.2018 | New York Stem Cell Foundation
Pollen taxi for bacteria
18.07.2018 | Technische Universität München
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
18.07.2018 | Materials Sciences
18.07.2018 | Life Sciences
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ERIC Number: EJ423676
Record Type: CIJE
Publication Date: 1990
Reference Count: 0
Elementary Proof That Some Angles Cannot Be Trisected by Ruler and Compass.
Quine, W. V.
Mathematics Magazine, v63 n2 p95-105 Apr 1990
Presented is a proof where special attention is accorded to rigor and detail in proving the lemma that relates ruler-and-compass constructions to arithmetical operations. The idea that some angles cannot be trisected by a ruler and compass is proved using three different cases. (KR)
Publication Type: Journal Articles; Guides - Classroom - Teacher
Education Level: N/A
Audience: Teachers; Practitioners
Authoring Institution: N/A
Note: Journal availability: See SE 547 378. | <urn:uuid:16d07699-587a-483a-aba9-32697ecba590> | 2.640625 | 182 | Structured Data | Science & Tech. | 35.665597 | 95,547,769 |
Physicists at UC Santa Barbara are manipulating light on superconducting chips, and forging new pathways to building the quantum devices of the future - including super-fast and powerful quantum computers.
Illinois has a burgeoning research and commercial nanotechnology environment. The University of Illinois and Northwestern University with its International Institute for Nanotechnolog have large and well-respected nanotechnology research programs. Currently, there are 29 companies in Illinois involved in nanotechnology-related business activities. In addition, there are 39 nanotechnology and nanoscience-related research and community organizations in Illinois.
A newly developed switchable mirror sheet uses new gasochromic switching that is completely different from conventional gasochromic switching methods. It can control the reflection of visible to near-infrared light at a switching speed about 20 times faster than that of conventional electrochromic switchable glass.
Scientists are developing an ambitious research project, known as 'Plasmaquo', aimed at developing a sensor which enables detecting the molecules that are released by bacteria to communicate with each other and, thus, understanding their paths of communication.
Researchers at Macquarie University have been perfecting a technique that may help see nanodiamonds used in biomedical applications. PhD student Jana Say has been working on processing the raw diamonds so that they might be used as a tag for biological molecules.
Scientists at Yale University have designed and tested a drug delivery system that shows early promise for improved treatment of lupus and other chronic, uncured autoimmune diseases, such as multiple sclerosis and Type 1 diabetes.
The salinity difference between fresh water and salt water could be a source of renewable energy. However, power yields from existing techniques are not high enough to make them viable. A solution to this problem may now have been found. Researchers have discovered a new means of harnessing this energy: osmotic flow through boron nitride nanotubes generates huge electric currents, with 1,000 times the efficiency of any previous system.
Nanoparticles filled with a drug could be a new tool for treating cancer in the future. A new study shows how such nanoparticles can be combined to secure the effective delivery of cancer drugs to tumour cells - and how they can be given properties to make them visible in MR scanners and thus rendered trackable. | <urn:uuid:fc88d37a-ad09-4831-94cc-9d7382282052> | 2.5625 | 470 | Content Listing | Science & Tech. | 14.969573 | 95,547,788 |
Thermodynamic Problem Solving.
1. Sketch System & Boundary2. Identify Unknowns (put them on sketch)3. Classify the System (open, closed, isolated)4. Identify Processes/States5. Write Governing Equations (including auxiliary eqns)6. Algebraically Solve7. Calculate Values (carrying units w/numbers)8. Check Results (eqns, algebra, calculations, signs, units) 9. Reflect (on the problem, on the solution, and/or on the problem solving process)
Heat as an Energy Transport Mode
For any thermodynamic cycle, the conversion efficiency can be defined as,
An alternative definition is,
The Second Law of Thermodynamics helps us define what the maximum conversion efficiency is for a heat engine!
The concept of an efficiency being greater than 100% makes people uneasy. Therefore, the conversion efficiency for a refrigerator is called the Cooling Coefficient of Performance (COPC). A refrigeration sysetm that is used for cooling is called a refrigerator.
The concept of an efficiency being greater than 100% makes people uneasy. Therefore, the conversion efficiency for a refrigerator is called the Heating Coefficient of Performance (COPH). A refrigeration system that is used for cooling is called a heat pump.
A Device Performance Parameter
A mechanical device can be work absorbing (e.g, a pump or compressor) or work delivering (e.g, a turbine). Therefore, there are two definitions of work efficiency,
Work Absorbing Device
Work Delivering Device | <urn:uuid:05d19126-cd32-4b22-88cd-7b9b82cf72c8> | 3.375 | 330 | Tutorial | Science & Tech. | 29.676087 | 95,547,790 |
That’s why we love Perl programming the perl dbi pdf 25,000 extensions on CPAN Perl 5 is a highly capable, feature-rich programming language with over 29 years of development. 25,000 open source distributions available for download.
Perl 6 Perl 6 is a sister language, part of the Perl family, not intended as a replacement for Perl 5, but as its own thing – libraries exist to allow you to call Perl 5 code from Perl 6 programs and vice versa. The Perl Foundation The Perl Foundation is dedicated to the advancement of the Perl programming language through open discussion, collaboration, design, and code. 8 NAMEVERSIONDESCRIPTIONHow do I find out which operating system I’m running under? DESCRIPTION This section of the Perl FAQ covers questions involving operating system interaction. These should contain more detailed information on the vagaries of your perl.
How do I find out which operating system I’m running under? The exec function’s job is to turn your process into another command and never to return. If that’s not what you want to do, don’t use exec. If you want to run an external command and still keep your Perl process going, look at a piped open, fork, or system. Some of these specific cases are shown as examples in other answers in this section of the perlfaq.
How do I print something out in color? In general, you don’t, because you don’t know whether the recipient has a color-aware display device. How do I read just one key without waiting for a return key? Controlling input buffering is a remarkably system-dependent matter. On many systems, you can just use the stty command as shown in getc, but as you see, that’s already getting you into portability snags. It even includes limited support for Windows.
However, using the code requires that you have a working C compiler and can use it to build and install a CPAN module. How do I check whether input is ready on the keyboard? How do I clear the screen? To clear the screen, you just have to print the special sequence that tells the terminal to clear the screen. Once you have that sequence, output it when you want to clear the screen. You can use the Term::ANSIScreen module to get the special sequence. The Term::Cap module can also get the special sequence if you want to deal with the low-level details of terminal control.
On Windows, you can use the Win32::Console module. How do I get the screen size? How do I ask the user for a password? This question has nothing to do with the web.
See a different FAQ for that. First, you put the terminal into “no echo” mode, then just read the password normally. How do I read and write the serial port? This depends on which operating system your program is running on.
Those listed above comprised the complete set for many Unicode releases, in other words, in the example above the list Bind was introduced. Unicode string representation, the convert command can also be used to extract data from a database. You can use the bytes 0xC1 and 0xC2 as sentinels, aSCII code points remain treated as if they are unassigned. This introduces another problem: what if you just know that your data is UTF, steve Friedl: SQL Injection Attacks by Example.
8 are sometimes a drag to your program. The most important area for Perl is to help administrators with patchwork and customization not covered by other, another program can pretend to be a person. Catmandu is a young yet active project and any kind of help is very much appreciated! Que no ejecuta el bloque de código subordinado.
Your system may use lockfiles to control multiple access. Make sure you follow the correct protocol. Unpredictable behavior can result from multiple processes reading from one device. See sysopen for more on this approach. 012″, and strip what you don’t need from the output. You’ll need to hard code your line terminators, in that case.
How do I decode encrypted password files? You spend lots and lots of money on dedicated hardware, but this is bound to get you talked about. Seriously, you can’t if they are Unix password files–the Unix password system employs one-way encryption. It’s more like hashing than encryption. The best you can do is check whether something else hashes to the same string. You can’t turn a hash back into the original string. How do I start a process in the background? | <urn:uuid:a434e11d-0c96-400e-9350-59ea32fcec54> | 2.5625 | 973 | Customer Support | Software Dev. | 60.905271 | 95,547,805 |
+44 1803 865913
By: Frank Spellman and Revonna Bieber
317 pages, Figs, tabs
This work explores a multidisciplinary approach to renewable energy, covering physical and engineering approaches and addressing economic, social, environmental, and policy issues surrounding the implementation of large-scale renewable energy systems. The author uses straightforward language and emphasizes the technical aspects and the practical applications of renewable energy, rather than math and theoretical science. The book contains case studies, examples from real world situations, to-the-point explanations, end-of-chapter questions and quizzes to reinforce learning, multiple illustrations, and a solutions manual.
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Preparation and Analysis of DNA Sequencing Gels
DNA sequencing involves a specific application of electrophoresis to resolve the linear single-stranded fragments produced during sequencing reactions, which differ in length by a single base pair. This necessitates using an acrylamide gel, usually at a concentration of 4–20%, of at least 40 cm in length and normally 0.4 mm thick.
KeywordsBottom Edge Straight Edge Sticky Tape Adjacent Lane Plate Assembly
- 3.Reed, A. P., Kost, T. A., and Miller, T. J. (1986) Simple improvements in 35S dideoxy sequencing. BioTechniques 4, 306.Google Scholar | <urn:uuid:aed583b4-399f-40a6-b896-096ed91f5de6> | 3.078125 | 145 | Academic Writing | Science & Tech. | 56.684167 | 95,547,852 |
Summary of the technology
The subject of the offer is a novel, affordable and environmentally friendly method of synthesis of oxide catalysts with a high surface area, dispersed on aluminosilicate supports
Applications: removal of volatile organic compounds from stationary sources
Description of the technology
Volatile Organic Compounds
It is estimated that around 60% of gaseous pollutants of Earth atmosphere are Volatile Organic Compounds (VOCs), which impact negatively human health by carcinogenic and mutagenic effects. Additionally, some VOCs participate in the formation of photochemical smog and influence the concentration of the stratospheric ozone. One of the methods of removal of VOCs is their catalytic oxidation in the presence of atmospheric oxygen. Nowadays, for these purposes, the catalysts based on precious metals and transition metals and their oxides deposited on a suitable porous support (eg. zeolites, SiO2, Al2O3) are utilized. An attractive alternative on the market of VOC oxidation catalysts could be highly effective materials based on natural clay materials that play the role of the supports for active phases in the form of metal oxides.
Aside from energy and chemical raw materials and metal ores, whose exploitation is carried out on a large scale, the natural minerals are nowadays widely used as economic catalytic supports. One of the groups of this type of materials are silicate and aluminosilicate layered minerals (so-called clay minerals), widely distributed in the form of easily accessible deposits in many places around the globe. Their catalytic properties can be easily enhanced by carrying out appropriate modifications, i.e. introduction of interlayer pillars by intercalation of the metal oligocations. The materials obtained in this way are characterized by a significantly developed of the specific surface, which enables to expose the catalytically active centers. The basic drawbacks of this synthesis path are, however, the limited possibilities of modifying the layered structure of aluminosilicate: only the oxides of these metals that form stable oligocations can be introduced into the structure of such materials.
The solution to these issues is a new technique for the synthesis of catalysts produced on the basis of clay materials. The materials obtained through this innovative method can be used in all technologies requiring the use of catalysts having an acidic surface, on which the catalytically active phase is dispersed, e.g. in the processes of dehydrogenation and oxidation of hydrocarbons or - important from the point of view of environmental protection - reactions of reduction of nitrogen oxides as well as oxidation of volatile organic compounds.
Among other advantages of the invention, the following should be mentioned:
- reduction of costs and the adverse environmental impact due to lack of the use of expensive and toxic raw materials and reagents, including surfactants;
- tenfold development of the surface area compared to the starting material, which allows exposure of the maximum number of surface catalytic centers;
- improved availability of catalytic centers for reagents by maximum exposure of the oxide phase due to exfoliation of the aluminosilicate layered structure;
- the possibility of the shaping of the final composition of the catalyst produced by selecting the type and amount of metal introduced, a 10-fold increase of the surface area comparing to the starting material which allows to expose maximum number of active catalytic and adsorption centers;
The offered solution is subject to a patent protection in Poland, the United States and selected European countries. Further development of the invention is conducted at the Faculty of Chemistry of the Jagiellonian University. Currently the Centre for Technology Transfer CITTRU is looking for companies and institutions interested in licensing and application of the presented method
Current development status
Desired business relationship
Centre Technology Transfer CITTRU
Technology Transfer Office
About Centre Technology Transfer CITTRU
Technology Transfer Office from PolandCentre Technology Transfer CITTRU
Centre for Innovation, Technology Transfer and University Development (CITTRU) is a part of Jagiellonian University, whose role is to promote university research, to support innovation and to create cooperation with the business. CITTRU main task is to offer the scientific achievements of the Jagiellonian University in the market by providing legal protection, licensing, sale of intellectual property rights, creation of academic business, coordination of company-ordered research projects, etc. Currently promoted technologies are mainly focused on new materials science, pharmacology and medical technology.
Inventions offered by Jagiellonian University are promoted and awarded during numerous exhibitions, e.g. 58th International Exhibition of Innovation, Research and New Technologies INNOVA (BRUSSELS 2009), 38th International Exhibition of Invention New Techniques & Products (Geneva 2010) or 24th International exhibition of environmental equipment, technologies and services POLLUTEC (Paris 2009). | <urn:uuid:519602ec-ff1e-4412-b244-a693d5212089> | 2.5625 | 990 | Product Page | Science & Tech. | -6.6894 | 95,547,857 |
KINGSTON — A University of Rhode Island doctoral student who surveyed the state for freshwater turtles and studied their habitat preferences found that the once-common spotted turtle is in trouble, due largely to habitat disturbance.
Scott Buchanan, a New Jersey native working in collaboration with URI Associate Professor Nancy Karraker, repeatedly visited 88 different wetlands in the state over three years and captured nearly 2,000 turtles of four different species. Just 50 were spotted turtles, a species considered by the state to be of high conservation concern and a candidate for the U.S. endangered species list.
“Throughout they’re range, populations of spotted turtles have declined extensively, and we can certainly say with a good deal of confidence that’s also the case in Rhode Island,” said Buchanan, who graduated from URI last month. “I found that they are associated with wetlands in forested landscapes, which means they are susceptible to development, forest fragmentation, wetland alteration and other human disturbances.”
Buchanan said that the largest populations of spotted turtles he found were in locations where human disturbance has been minimal. “So now it’s a matter of managing those landscapes in an appropriate way,” he added.
Habitat alteration is not the only conservation concern the species faces, however. The illegal collection of wild turtles for the pet trade is also a problem.
“Spotted turtles will command a formidable sum in the pet trade, which is unfortunate,” Buchanan said, noting that he encountered people during his research who had captured spotted turtles they intended to bring home to keep as pets but released them at his insistence. “It’s really easy for someone to deplete an entire population of them very quickly.”
During his turtle surveys, Buchanan also found a non-native turtle called a red-eared slider in more wetlands than he found spotted turtles. The slider is a species commonly purchased at pet stores and frequently released into the wild after their owners no longer wish to care for them. He said that wetlands close to human populations, especially those with easy access from roads, are the most likely place to find red-eared sliders in Rhode Island.
“They’re an especially detrimental invasive species,” he said. “It’s a good bet that all the sliders we found are turtles that were bought at pet stores. We don’t know if they’re reproducing in the wild.”
Eastern painted turtles and common snapping turtles, the two most common species of freshwater turtles in Rhode Island, were found in abundance during Buchanan’s turtle surveys.
“They were everywhere, with no strong pattern as to where we might find them across different landscape types,” he said.
What can be done to protect the region’s declining spotted turtle populations?
“It would mean protecting and preserving wetlands, especially forested wetlands, including small wetlands like vernal pools where they sometimes overwinter,” Buchanan said. “It would also mean minimizing fragmentation of the landscape surrounding those wetlands. And it’s also really important that we protect the turtles themselves from illegal collection. That’s an increasing concern among conservation biologists.”
As Buchanan prepares to graduate from URI, he will share his data with a region-wide team of biologists collecting information about the three turtle species being considered for inclusion on the U.S. endangered species list – spotted, wood and Blanding’s turtle.
“The habitat information we collected could help determine where populations of spotted turtles occur and help protect and appropriately manage those populations into the future,” he said. | <urn:uuid:8cce5d53-3ad3-4553-ad7c-b0de96176cc3> | 2.859375 | 757 | News Article | Science & Tech. | 35.790166 | 95,547,893 |
In a study of New Zealand’s “living dinosaur” the tuatara, evolutionary biologist, and ancient DNA expert, Professor David Lambert and his team from the Allan Wilson Centre for Molecular Ecology and Evolution recovered DNA sequences from the bones of ancient tuatara, which are up to 8000 years old.
They found that, although tuatara have remained largely physically unchanged over very long periods of evolution, they are evolving - at a DNA level - faster than any other animal yet examined. The research will be published in the March issue of Trends in Genetics.
“What we found is that the tuatara has the highest molecular evolutionary rate that anyone has measured,” Professor Lambert says.
The rate of evolution for Adélie penguins, which Professor Lambert and his team have studied in the Antarctic for many years, is slightly slower than that of the tuatara. The tuatara rate is significantly faster than for animals including the cave bear, lion, ox and horse.
“Of course we would have expected that the tuatara, which does everything slowly – they grow slowly, reproduce slowly and have a very slow metabolism – would have evolved slowly. In fact, at the DNA level, they evolve extremely quickly, which supports a hypothesis proposed by the evolutionary biologist Allan Wilson, who suggested that the rate of molecular evolution was uncoupled from the rate of morphological evolution.”
Allan Wilson was a pioneer of molecular evolution. His ideas were controversial when introduced 40 years ago, but this new research supports them.
Professor Lambert says the finding will be helpful in terms of future study and conservation of the tuatara, and the team now hopes to extend the work to look at the evolution of other animal species.
“We want to go on and measure the rate of molecular evolution for humans, as well as doing more work with moa and Antarctic fish to see if rates of DNA change are uncoupled in these species. There are human mummies in the Andes and some very good samples in Siberia where we have some collaborators, so we are hopeful we will be able to measure the rate of human evolution in these animals too.”
The tuatara, Sphendon punctatus, is found only in New Zealand and is the only surviving member of a distinct reptilian order Sphehodontia that lived alongside early dinosaurs and separated from other reptiles 200 million years ago in the Upper Triassic period.
Scientists uncover the role of a protein in production & survival of myelin-forming cells
19.07.2018 | Advanced Science Research Center, GC/CUNY
NYSCF researchers develop novel bioengineering technique for personalized bone grafts
18.07.2018 | New York Stem Cell Foundation
A new manufacturing technique uses a process similar to newspaper printing to form smoother and more flexible metals for making ultrafast electronic devices.
The low-cost process, developed by Purdue University researchers, combines tools already used in industry for manufacturing metals on a large scale, but uses...
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
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Craton-scale module: Isotopic mapping of the Superior Craton
A research update by Metal Earth researcher David Mole.
David Mole is planning, designing and implementing a research program that will allow Metal Earth to collect large volumes of isotopic data on hundreds of samples, quickly and efficiently across the Superior Craton. This will be the largest high-quality geochemical and isotopic dataset for any Archean craton. This offers unique opportunities to understand the tectonics that drove geological change and activity in the early Earth, the formation and evolution of the crust, and timing and localisation of major mineral provinces, which form in response to those processes.
Previous isotopic mapping in Western Australia demonstrated that cratons (such as the Yilgarn and Pilbara), have a cryptic history and corresponding architecture that can be shown best by mapping their isotopic data spatially. The craton architecture corresponded to the location of different types of mineral deposit. In the Yilgarn, orogenic gold and komatiite-hosted Ni-Cu-PGE systems occurred in juvenile, young, mantle-derived crust, adjacent (at the margins of) older crustal blocks within the craton. In contrast, banded iron formation (BIF) deposits were concentrated within the older crustal regions. These correlations suggest that isotopic mapping could make a powerful area selection tool, for the strategic ranking of exploration targets.
What is isotopic mapping?
Using a spatially-extensive isotopic dataset (in this case Lu-Hf) to map variations in crustal age, source and evolution, and image the crustal architecture of a region.
Why is crustal architecture important?
Archean cratons are heterogeneous in many geological attributes, especially mineralisation. The constraining architecture helps us understand time-space variations in the evolution of the craton.
Why use radiogenic isotopes?
They are time-resolved – hence they show the architecture as it was in the Archean
What about other isotopic systems?
There are plans further into this project to collect O-isotopes on the zircons – this will constrain temperatures and sources of external components
One of the primary project objectives is to provide the exploration community with an isotopic map that can be used in a similar way to pre-competitive data provided by the geological surveys.
This will be a new and valuable tool that will help drive expansion of greenfields exploration into new or under-explored areas.
Further to this, the dataset the team is building will allow Metal Earth to investigate spatial and temporal development of archean crust in unprecedented detail. As well as offering the potential for important academic discoveries related to the establishment of the current habitable Earth, this study will also drive a greater understanding of the fundamental first-order processes behind the development of major ore provinces.
Who will benefit from these findings the most?
|"The fundamental dataset behind this project offers exciting developments for both economic geology and blue-sky science."||"We hope the dataset and the maps we build will have real effects and implications for industry and explorers, and become a tool they can use to further refine selection decisions. Further to this, we also hope the data will aid in the fundamental understanding of how major mineral provinces form, and the science behind the correlations of certain ore deposits and crustal history. Finally, the data collected in this project will allow fundamental insights into the understanding of tectonics and crustal evolution in the early Earth, and by proxy the development of the atmosphere-biopshere system. Ultimately the understanding of these processes will help us constrain the development of the Earth into a habitable planet full of life."|
The vast majority of all isotopic and geochemical data will be collected on zircons from felsic volcanics and granitoids from all over the Superior Craton. These rocks represent the crust of the craton, and hence data from their zircons can be used as a medium for the nature of the crust from which they formed. This project will be collecting data in three isotopic systems (U-Pb, Lu-Hf, and 18O/16O), as well as trace elements in zircons. The new laser ablation split stream (LASS) system at Laurentian University will be used to collect U-Pb ages and Lu-Hf isotopic data synchronously, from the sample laser pit.
This will allow the team to data the rocks, as well as understand the age and nature of their source (i.e. mantle-derived, or crustally-reworked). Zircon trace element data allow the investigation of processes and features important for mineralisation potential, such as hydration and oxidation state of the magma. Oxygen isotopes will be collected separately on an ion microprobe to allow the team to constrain whether a low- or high-temperature hydrothermal component has been incorporated into the magma, and whether the crust was extracted from the mantle, or reworked within the crust itself. The combination of these processes have important implications for the history and origin of the crust in space and time, and mapping these allow us to map the prospectivity of the crust.
Figure 1. Lu-Hf (eHf) map of the Yilgarn Craton at 2,720–2,600 Ma. (A) Hf isotope map with the location of sample sites and komatiite localities. (B) Interpretive map of the area, showing the individual crustal blocks identified from the Hf isotope map and corresponding probability density plots. The blue curve represents the median eHf for discrete temporal groups (ng), whereas the red curve represents all of the individual grain analyses (na). Dark gray polygons shown in the background of all maps represent supracrustal belts (Mole et al., 2014).
Utilizing the Superior Data Compilation
|"The release of the Superior Data Compilation has been very important for this project in particular."||"As our work covers the entire craton, it is vital to have a good, craton-wide geological understanding of the area, and this must be embodied into a spatial form. Without this detailed craton-scale geology we would not be able to make efficient comparisons between the basic geology and the isotopic data. We feel that the integration of the Superior data compilation and our isotopic mapping will be a valuable tool to industry and academic in Canada, and worldwide, and result in a step-change in our understanding of the Earth’s largest Archean craton."|
The project is estimated to take 4 years with an initial first version of the Hf-isotope map completed. Further time will be required to improve and finalize the map as well as integrate other datasets such as the O-isotopes, zircon trace elements and whole-rock geochemistry. The length of the project does not mean tangible outcomes will not be felt sooner. The project is compartmentalised into a number of zones or quadrants, i.e. the Abitibi is one such quadrant. New isotopic data, and subsequent maps, from these areas will be presented as they are finalized allowing the data to be utilized by explorers as quickly as possible.
At this stage the team is designing a protocol to collect and prepare samples, when, where and how to run those samples and in what order. This stage of the project is almost complete, with the first analyses from Abitibi rocks expected to take place in July.
Figure 2. Sm-Nd (eNd) map of the Yilgarn Craton from Mole et al. (2013).
Figure 3. Distribution of BIF-hosted iron and orogenic gold deposits in the Yilgarn Craton, shown on top of the eNd isotope map (Mole et al., 2013). Note gold deposits prefer the juvenile regions, whereas iron deposits prefer more reworked crustal blocks.
Update by Metal Earth researcher David Mole | <urn:uuid:18d4fd92-3482-4d99-b474-2c4b2ba1ecfe> | 2.78125 | 1,672 | News (Org.) | Science & Tech. | 31.409636 | 95,547,906 |
When do we say that work is done?
A pair of bullocks exerts a force of 140 N on a plough. The field being ploughed is 15 m long. How much work is done in ploughing the length of the field?
A force of 7 N acts on an object. The displacement is, say 8 m, in the direction of the force (see the given figure). Let us take it that the force acts on the object through the displacement. What is the work done in this case?
An object thrown at a certain angle to the ground moves in a curved path and falls back to the ground. The initial and the final points of the path of the object lie on the same horizontal line. What is the work done by the force of gravity on the object?
- Science Textbook for Class 9 | <urn:uuid:83fb83f5-5107-4e3e-b743-8d6111df0909> | 3.140625 | 172 | Content Listing | Science & Tech. | 86.68442 | 95,547,919 |
A lot of the not too long ago reserved words and phrases start with an underscore accompanied by a cash letter, since identifiers of that kind have been Earlier reserved by the C standard to be used only by implementations. Given that present system source code should not are actually making use of these identifiers, it wouldn't be impacted when C implementations started out supporting these extensions on the programming language.
Back when acquiring OO and generic programming in precisely the same language was even now new, “multiparadigm programming” was initially a flowery way of claiming “programming employing more than one programming design, each to its ideal result.” One example is, using object-oriented programming when operate-time resolution amongst different object kinds is necessary and generic programming when static style security and operate-time effectiveness is in a quality. The natural way, the main power of multiparadigm programming is in courses the place more than one paradigm (programming design) is applied, to make sure that it would be difficult to obtain the exact same impact by composing a method away from pieces penned in languages supporting unique paradigms.
The C++ programming language was devised by Bjarne Stroustrup being an method of offering object-oriented features that has a C-like syntax.
In 2008, the C Expectations Committee released a complex report extending the C language to handle these issues by supplying a typical common for all implementations to adhere to.
Bjarne Stroustrup started out Focus on what grew click this site to become C++ in 1979. The initial Model was identified as “C with Classes”. The very first version of C++ was made use of internally in AT&T in August 1983. The name “C++” was applied late that calendar year.
You’ll see how to accessibility and perform with databases in Perl, compose CGI scripts to create Websites and beyond. Safety is bang up-to-date, using Perl five.six in all our illustrations and there’s an useful reference region inside the again.
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So are generic programming methods applying templates. Both of those are essential strategies to precise her explanation polymorphism – at operate time and at compile time, respectively. Plus they get the job done wonderful with each other in C++.
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By examining if our implicit object is similar to the one particular becoming passed in for a parameter, we might have our assignment operator just return quickly with no performing any other do the job.
On top of that, in most expression contexts (a noteworthy exception is as operand of sizeof), the identify of the array is immediately converted to your pointer to your array's initially component. | <urn:uuid:c7aa4e9a-f445-4194-8e10-c6d0ba35d708> | 2.53125 | 731 | Tutorial | Software Dev. | 33.309883 | 95,547,931 |
Same as title.
What is the difference between Gödel’s Completeness and Incompleteness Theorems?
First, note that, in spite of their names, one is not a negation of the other.
The completeness theorem applies to any first order theory: If $T$ is such a theory, and $\phi$ is a sentence (in the same language) and any model of $T$ is a model of $\phi$, then there is a (first-order) proof of $\phi$ using the statements of $T$ as axioms. One sometimes says this as “anything true is provable.”
The incompleteness theorem is more technical. It says that if $T$ is a first-order theory that is:
then $T$ is not complete, i.e., there is at least one sentence $\phi$ in the same language as $T$ such that there is a model of $T$ and $\phi$, and there is also a model of $T$ and $\lnot\phi$. Equivalently (by the completeness theorem), $T$ cannot prove $\phi$ and also $T$ cannot prove $\lnot\phi$.
One usually says this as follows: If a theory is reasonable and at least modestly strong, then it is not complete.
The second incompleteness theorem is more striking. If we actually require that $T$ interprets Peano Arithmetic, then in fact $T$ cannot prove its own consistency. So: There is no way of proving the consistency of a reasonably strong mathematical theory, unless we are willing to assume an even stronger setting to carry out the proof. Or: If a reasonably strong theory can prove its own consistency, then it is in fact inconsistent. (Note that any inconsistent theory proves anything, in particular, if its language allows us to formulate this statement, then it can prove that it is consistent).
The requirement that $T$ is recursively enumerable is reasonable, I think. Formally, a theory is just a set of sentences, but we are mostly interested in theories that we can write down or, at least, for which we can recognize whether something is an axiom or not.
The interpretability requirement is usually presented in a more restrictive form, for example, asking that $T$ is a theory about numbers, and it contains Peano Arithmetic. But the version I mentioned applies in more situations; for example, to set theory, which is not strictly speaking a theory about numbers, but can easily interpret number theory. The requirement of interpreting Peano Arithmetic is two-fold. First, we look at theories that allows us (by coding) to carry out at least some amount of common mathematical practice, and number theory is singled out as the usual way of doing that. More significantly, we want some amount of “coding” within the theory to be possible, so we can talk about sentences, and proofs. Number theory allows us to do this easily, and this is way we can talk about “the theory is consistent”, a statement about proofs, although our theory may really be about numbers and not about first order formulas.
If I can add some comments,
I think it is useful to state Godel’s Completeness Theorem in this form : if a wff A of a first-order theory T is logically implied by the axioms of T, then it is provable in T, where “T logically implies A” means that A is true in every model of T.
The problem is that most of first-order math theories have more than one model; in particular, this happens for PA and related systems (to which Godel’s (First) Incompleteness Theorem applies).
When we “see” (with insight) that the unprovable formula of Godel’s Incompleteness Theorem is true, we refer to our “natural reading” of it in the intended interpretation of PA (the structure consisting of the natural number with addition and multiplication).
So, there exist some “unintended interpretation” that is also a model of PA where the aforesaid formula is not true. This in turn implies that the unprovable formula isn’t logically implied by the axioms of PA. | <urn:uuid:9470bf7c-ba05-4ce2-bfc7-2f4c307415cd> | 2.796875 | 911 | Q&A Forum | Science & Tech. | 46.187945 | 95,547,944 |
|MLA Citation:||Bloomfield, Louis A. "Question 626"|
How Everything Works 16 Jul 2018. 16 Jul 2018 <http://howeverythingworks.org/print1.php?QNum=626>.
Like everything else in the universe, light exhibits both wave and particle behaviors. When it is traveling through space, light behaves as a wave. That means that its location is generally not well defined and that it can simultaneously pass through more than one opening (the way a water wave can when it encounters a piece of screening). But when light is emitted or absorbed, it behaves as a particle. It's created all at once when it's emitted from a particular location and it disappears all at once when it's absorbed somewhere else. This wave/particle arrangement is true of everything, including objects such as electrons or atoms: while they are traveling unobserved, they behave as waves but when you go looking for them, they behave as particles. | <urn:uuid:028ee82a-5101-482f-8218-f5c2b96907d8> | 3.421875 | 197 | Knowledge Article | Science & Tech. | 54.823452 | 95,547,951 |
Focal (Flagship) vertebrates. Figure 10.1 Aldabrachelys gigantea was introduced to an island in Mauritius as a taxon substitute for an extinct giant tortoise that dispersed tree fruits on the island. Focal (Flagship) vertebrates.
Figure 10.1 Aldabrachelysgigantea was introduced to an island in Mauritius as a taxon substitute for an extinct giant tortoise that dispersed tree fruits on the island
Figure 10.2 The spotted frog (Ranaluteiventris), a species that lives in floodplain wetlands, was a focal species of the Provo River restoration project
Figure 10.3 Larger tracts of restored forest in Costa Rica provided better foraging opportunities for insectivorous birds than smaller tracts
Figure 10.4 Restoration of forest buffers around Chitwan National Park ended open grazing and required that villagers collect fodder for livestock
Figure 10.6 Within a complex of restored wetlands in North Carolina, breeding wood frogs curtailed egg-laying following fish invasions and used nearby ponds without fish
Figure 10.7 Sustaining a metapopulation requires more habitat area than sustaining individual populations, a mating pair, or a single individual
Figure 10.8 Eurasian spoonbills (Platalealeucorodia) breed in wetlands in the Skjern River restoration area, but also rely on wetlands in West Africa to overwinter
Figure 10.9 (A) Results of a study of restored eucalyptus forests in Australia. (B) Many birds, such as this fuscous honeyeater,find these forests of little use until they are fully recovered
Figure 10.10 Researchers erect an artificial bird perch to determine if this method can increase seed dispersal by frugivorous birds in a degraded tropical forest in Kalimantan, Indonesia
Figure 10.12 Gray reef sharks (Carcharhinusamblyrhynchos) increased eightfold in no-take reserves in the Great Barrier Reef Marine Park within a few years of their establishment
Figure 10.13 Probable “Countries of Origin” of stranded nets found along the shores of the Gulf of Carpentaria (Australia) as identified by the WWF Net Kit (see Figure 5.5)
Figure 10.17 Eradication of introducedrats from some Galápagos Islands posed a risk to the rare Galápagos hawk, so they were captured prior to treatment and held in an aviary on a nearby island
Figure 10.18 A Judas goat following release in South Australia is attracting the remaining feral goats that need be removed to complete eradication
Figure 10.19 Following a cat eradication program that was completed in 2004, the sooty tern population on Ascension Island rose, although not consistently and may now be limited by rats
Figure 10.22 A rare brush-tailed rock wallaby joey in the pouch of a yellow-footed rock wallaby is being cross-fostered at the Adelaide Zoo (Australia)
Figure 10.23 The takahe, a grassland bird from New Zealand’s South Island, was saved from extinction by establishing insurance populations on small offshore islands while invasive plants were removed and restoration of permanent sites occurred.
Figure 10.24 Following major oil spills, oil-coated birds like this African penguin (Spheniscusdemersus) are often removed from the contaminated area, cleaned, and released
Figure 10.25 Peregrine falcons (Falco peregrinus) reintroduced to the New River Gorge National Park (West Virginia, U.S.) at a site where they receive food and shelter as they fledge
Figure 10.27 Breeding colonies of fluttering shearwaters and diving petrels were restored at Mana Island by translocating nestlingsand providing for them until they fledge. Vocalizations were broadcast from suitable nesting sites using sound systems so returning birds can locate sites more readily.
Figure 10.30 Biologists in Tram Chim National Park periodically map the spatial extent of the invasive species Mimosa pigra so that they can monitor changes in its distribution | <urn:uuid:4345bf7a-321f-4a08-bc20-86e7a5cf03da> | 3.71875 | 857 | Structured Data | Science & Tech. | 33.18415 | 95,547,969 |
Members of the Tuna Research and Conservation Center (TRCC) prepare to tag a tuna
TOPP Principal Investigator Dr. Barbara Block (right) and Dr. Heidi Dewar (left) prepare to tag a giant bluefin tuna.
What will some 4,000 of the smartest dressed elephant seals, tuna fish, albatrosses, leatherback sea turtles, great white sharks, and other pelagic megafauna in the Pacific all be wearing in the coming seasons? How about the latest in microprocessor-based electronic tags, some no bigger than oversized cufflinks? Its all in a continuing effort to understand the habits of marine animals in that part of the world: what exactly lives where and why, what their migration routes and diving behaviors might be, and what might be going on in the ocean all around them – temperature, salinity and other physical data.
Its called the TOPP program – Tagging of the Pacific Pelagics – and it is funded as one of the six pilot projects currently funded as part of the Census of Marine Life (COML). It will be a 10-year-long undertaking over a vast part of the worlds oceans, funded by the Office of Naval Research in partnership with the Sloan and Packard Foundations.
In recent years, technology that allows us to examine the migrations of large oceanic animals (pop-up satellite archival tags, satellite-linked data recorders, archival and sonic tags) has proven enormously successful. Animal movements and behaviors can be linked to oceanographic processes by integrating biological and physical data providing both atmospheric and oceanographic information, and offering unprecedented insights into the relationship between physical ocean processes and top predators like tunas, dolphins, and sharks. Fifteen to twenty species of pelagic organisms from several trophic levels, many with similar patterns of spatial and temporal distributions, will be monitored throughout the North Pacific. Simultaneous tagging of the target marine species will permit the monitoring of their movement and behavior relative to environmental conditions. Results from TOPP will provide a framework for future management and conservation of these economically and ecologically valuable resources.
"To be able to electronically tag and track many individuals of several different species across immense areas of the ocean is a daunting task," says ONR marine mammal expert Robert Gisiner. "But, this program is going to allow us to study the movements of these animals both spatially and temporally at resolutions previously unknown."
Gail Cleere | 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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Flumerfelt, Raymond W. Department of Chemical and Biomolecular Engineering, University of Houston, Houston, Texas.
Wang, Su Su Department of Mechanical Engineering, University of Houston, Houston, Texas.
Last reviewed:February 2017
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The extraction of kinetic energy from the wind and conversion of it into a useful type of energy: thermal, mechanical, or electrical. The use of wind energy by various devices to propel ships, pump water, grind grains, and perform other energy-intensive tasks has existed since the early Egyptians. The nineteenth and twentieth centuries brought fossil fuels and fossil-fuel engines, and wind had a minor role as an energy conversion source. Only since the oil embargo of 1973 has wind been rediscovered and started to emerge as an important energy source. Advances in large airfoil structure manufacturing, composite materials, computational aerodynamics, and machine design and control have produced larger, lighter, and more efficient and reliable wind energy power systems than ever before. Wind energy represents a growing percentage of the electricity grids of a number of countries (Fig. 1). See also: Electric power generation; Energy sources; Wind
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If you enjoy watching meteor showers, the folks at NASA are expecting as many as 200 meteors per hour during tonight’s peak of the Perseid meteor shower that graces our sky every August.NASA says it expects this year’s show to be one of the best potential meteor viewing opportunities of the year.”Forecasters are predicting a Perseid outburst this year with double normal rates on the night of Aug. 11-12,” said Bill Cooke, from NASA’s Meteoroid Environment Office. “Under perfect conditions, rates could soar to 200 meteors per hour.”The association says that the last Perseid outburst, which is a shower with more meteors than usual due to the debris trail passing closer to Earth, occurred in 2009. The Perseid meteors travel at roughly 132,000 miles per hour, peaking at temperatures ranging from 3,000 to 10,000 degrees Fahrenheit in the Earth’s atmosphere. In other sky-watching news, scientists from Appalachian State University believe they have captured images of the mysterious “Brown Mountain Lights,” the folkloric lights with stories that date back over 100 years in the Morganton area of North Carolina. The scientists, Daniel Caton and Lee Hawkins of the physics and astronomy department at App State, used two time-lapse digital cameras near Brown Mountain on the night of July 16 to capture the footage.”This is the first time we’ve had a dual detection (on both cameras),” Caton said. “It was something out there. It came on and went back off virtually instantly four times over several minutes. We’ve eliminated all the things that are likely man-made natural sources, so we’re left with no real explanation other than it’s whatever the lights might actually be.”Caton has been attempting to capture such footage since 2011. Theories of what may cause the lights range drastically from ball lightning to naturally occurring gases rising from the mountain to even more out-there cosmic possibilities. “It’s intriguing,” Caton said. “I was about ready to give up, so this was one of those moments when you look at the screen and go, ‘What was that?’ It’s the first time we’ve captured something that we can’t easily explain.” To check out YouTube videos of the spotting, click here and here for footage from each of the cameras.
All across North Carolina there are pockets of distinctive regional recipes carefully passed down into the hands of cooks by friends and relatives all the time. Unless you are fortunate enough to garner a cooking […]
NEW YORK – Surviving members of Lynyrd Skynyrd have filed a lawsuit against the Southern rock band’s former drummer to halt the production of a movie depicting the 1977 plane crash that killed lead singer […]
LOS ANGELES This Memorial Day weekend signals a sluggish end to a dreary summer box office start. This four-day weekend’s total domestic earnings ($172.3 million) are the lowest recorded since 1999 ($142.5 million) when […] | <urn:uuid:c4822187-6e7c-486d-9095-d5564337a6b5> | 3.0625 | 651 | Content Listing | Science & Tech. | 52.116983 | 95,548,004 |
Species Detail - Atlantic Puffin (Fratercula arctica) - 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).
Protected Species: Wildlife Acts || Threatened Species: Birds of Conservation Concern || Threatened Species: Birds of Conservation Concern >> Birds of Conservation Concern - Amber List
11 January (recorded in 1997)
15 December (recorded in 1991)
National Biodiversity Data Centre, Ireland, Atlantic Puffin (Fratercula arctica), accessed 22 July 2018, <https://maps.biodiversityireland.ie/Species/10029> | <urn:uuid:cc0eb5cd-23fc-4d03-8431-bdaff87039b9> | 2.828125 | 172 | Structured Data | Science & Tech. | 23.693158 | 95,548,018 |
A UC Riverside-led team of astronomers have taken us a step closer to better understand the formation and destruction mechanisms of dust molecules in the distant universe
A molecule found in car engine exhaust fumes that is thought to have contributed to the origin of life on Earth has made astronomers heavily underestimate the amount of stars that were forming in the early Universe, a University of California, Riverside-led study has found.
In this study, astronomers used data from the Keck and Spitzer telescopes to trace the star forming and dusty regions of galaxies at about 10 billion years ago. The picture in the background shows the GOODS field, one of the five regions in the sky that was observed for this study.
Credit: Mario De Leo-Winkler with images from the Spitzer Space Telescope, NASA, ESA and the Hubble Heritage team.
That molecule is called polycyclic aromatic hydrocarbon (PAH). On Earth it is also found in coal and tar. In space, it is a component of dust, which along with gas, fills the space between stars within galaxies.
The study, which was just published in the Astrophysical Journal, represents the first time that astronomers have been able to measure variations of PAH emissions in distant galaxies with different properties. It has important implications for the studies of distant galaxies because absorption and emission of energy by dust particles can change astronomers' views of distant galaxies.
"Despite the ubiquity of PAHs in space, observing them in distant galaxies has been a challenging task," said Irene Shivaei, a graduate student at UC Riverside, and leader of the study. "A significant part of our knowledge of the properties and amounts of PAHs in other galaxies is limited to the nearby universe."
The research was conducted as part of the University of California-based MOSDEF survey, a study that uses the Keck telescope in Hawaii to observe the content of about 1,500 galaxies when the universe was 1.5 to 4.5 billion years old. The researchers observed the emitted visible-light spectra of a large and representative sample of galaxies during the peak-era of star formation activity in the universe.
In addition, the researchers incorporated infrared imaging data from the NASA Spitzer Space Telescope and the European Space Agency-operated Herschel Space Observatory to trace the polycyclic aromatic hydrocarbon emission in mid-infrared bands and the thermal dust emission in far-infrared wavelengths.
The researchers concluded that the emission of polycyclic aromatic hydrocarbon molecules is suppressed in low-mass galaxies, which also have a lower fraction of metals, which are atoms heavier than hydrogen and helium. These results indicate that the polycyclic aromatic hydrocarbon molecules are likely to be destroyed in the hostile environment of low-mass and metal-poor galaxies with intense radiation.
The researchers also found that the polycyclic aromatic hydrocarbon emission is relatively weaker in young galaxies compared to older ones, which may be due to the fact that polycyclic aromatic hydrocarbon molecules are not produced in large quantities in young galaxies.
They found that the star-formation activity and infrared luminosity in the universe 10 billion years ago is approximately 30 percent higher than previously measured.
Studying the properties of the polycyclic aromatic hydrocarbon mid-infrared emission bands in distant universe is of fundamental importance to improving our understanding of the evolution of dust and chemical enrichment in galaxies throughout cosmic time. The planned launch of the James Webb Space Telescope in 2018 will push the boundaries of our knowledge on dust and polycyclic aromatic hydrocarbon in the early universe.
The Astrophysical Journal paper is called "The MOSDEF Survey: Metallicity Dependence of PAH Emission at High Redshift and Implications for 24 μm Inferred IR Luminosities and Star Formation Rates at z ∼ 2."
In addition to Shivaei, the authors are: Naveen Reddy, Brian Siana, and Bahram Mobasher, of UC Riverside; Alice Shapley and Ryan L. Sanders, of UCLA; Mariska Kriek, Sedona H. Price, and Tom Zick, of UC Berkeley; and Alison L. Coil and Mojegan Azadi, of UC San Diego.
Mario De Leo-Winkler, a postdoctoral researcher in the UCR Department of Physics and Astronomy, made significant contributions to this article.
The University of California, Riverside is a doctoral research university, a living laboratory for groundbreaking exploration of issues critical to Inland Southern California, the state and communities around the world. Reflecting California's diverse culture, UCR's enrollment is now nearly 23,000 students. The campus opened a medical school in 2013 and has reached the heart of the Coachella Valley by way of the UCR Palm Desert Center. The campus has an annual statewide economic impact of more than $1 billion. A broadcast studio with fiber cable to the AT&T Hollywood hub is available for live or taped interviews. UCR also has ISDN for radio interviews. To learn more, call (951) UCR-NEWS.
Sean Nealon | 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....
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This page list all the Node.js related tutorial and examples.
- How To Install Node JS In Windows
- Use Node.js To Create Http Web Server And Process Web Page Example
Show you examples about how to use node.js http module to create a http web server and process web page with request module.
- How To Debug Node.js Application With Command Line
Show you how to use node debug command to debug node.js application.
- How To Run / Debug Node.js Application With Eclipse
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Example about how to install Nodeclipse plugin in eclipse to create and debug node js application.
- Node JS User Registration Login Example
A user register and login example implemented with node js. It show you how to create custom node module and how to use built-in module such as url, http and querystring.
- Node JS Get All Files In Directory Example
Example about how to use node JS to get all folders and files under parent folder in web server, and return the child folder data in JSON format string.
- Node JS Async Module Example
Tell you how to install node async module from npmjs.com and how to use it’s various methods to control js function execution flow and control collection items.
- Implement Queue Using Node JS Async Module Example
Example about how to use node js async module to implement and execute queue object.
- How To Use Node Package Manager
This article tell you what NPM is and how to use it to install, uninstall, update and search node modules locally and globally with examples.
- How To Create Custom NPM Modules
This article show you examples about NPM module file structure and how to create custom NPM module with command line. It also tell you how to register user to npmjs.com and publish your NPM module.
- Node JS Callback Example
Example about what is callback and how to use callback in Node JS. It also compare block and none block JS code in execution speed.
- Node JS Event Loop And Custom Event Example
Introduce Node JS event driven and callback function process diagram. Also with example about how to create and process custom event.
- Node JS EventEmitter Example
Introduce EventEmitter class methods and how to use it to emit events to registered event listeners. Also show examples about how to extends it to make custom js class emit events.
- Node JS Buffer Example
Example about how to use Node JS Buffer module to operate character or binary data.
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Introduce how node js implement read stream, write stream and pipe stream with examples about read file, write file, transfer data between files, compress file to zip and unzip.
- Node JS Get User Input From Command Line Prompt Example
Tell you how to get user input data from command line in node js application with examples.
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Example about how to use node js dgram module to create udp client and server to broadcast packet between them.
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An example about how to use fs module watch function to monitor a server side data file and send newly added text data back to client browser.
- Node JS Create Publish And Use Custom Package Module Example
This example will show you how to create custom node js module, how to publish the module to https://www.npmjs.com/ and how to use it in your node app.
- Node JS Read Write File Examples
Example about how to read write fils both synchronously and asynchronously in node js application.
- Node JS Http Server Get Post Example
Example about how to implement http web server and how to extract http get and post request data in node js application.
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Tell you how to use zlib or request node js module to decompress zipped web page content.
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Show you how to implement TCP socket client server communication in node js app.
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On Monday, Aug. 21, 2017, millions in the U.S. will have their eyes to the sky as they witness a total solar eclipse. The moon's shadow will race across the United States, from Oregon to South Carolina. The path of this shadow, also known as the path of totality, is where observers will see the moon completely cover the sun. And thanks to elevation data of the moon from NASA's Lunar Reconnaissance Orbiter, or LRO, coupled with detailed NASA topography data of Earth, we have the most accurate maps of the path of totality for any eclipse to date.
Eclipse maps have long been used to plot the predicted path of the moon's shadow as it crosses the face of Earth. Friedrich Wilhelm Bessel and William Chauvenet, two prominent 19th century astronomers and mathematicians, developed the math still used to make eclipse maps -- long before computers and the precise astronomical data gathered during the Space Age.
Traditionally, eclipse calculations assume that all observers are at sea level and that the moon is a smooth sphere that is perfectly symmetrical around its center of mass. The calculations do not take into account different elevations on Earth and the moon's cratered, uneven surface.
For slightly more accurate maps, people use elevation tables and plots of the lunar limb -- the edge of the visible surface of the moon as seen from Earth. Until recently, astronomers have used the limb profiles published in 1963 by astronomer Chester Burleigh Watts to create eclipse maps of the moon's path of totality. To produce his profiles, Watts designed a machine that traced 700 photographs covering every angle of the moon visible from Earth.
However, eclipse calculations have gained even greater accuracy based on topography data from LRO observations.
A new look at an ancient phenomenon
Using LRO elevation maps, NASA visualizer Ernie Wright at Goddard Space Flight Center in Greenbelt, Maryland, created a continuously varying lunar limb profile as the moon's shadow passes over the United States as it will during the upcoming eclipse. The mountains and valleys along the edge of the moon's disk affect the timing and duration of totality by several seconds. Wright also used several NASA data sets to provide an elevation map of Earth so that eclipse observer locations were depicted at their true altitude.
The resulting visualizations show something never seen before: the true, time-varying shape of the moon's shadow, with the effects of both an accurate lunar limb and the Earth's terrain.
"We couldn't have done visualizations like this even 10 years ago," Wright said. "This is a confluence of increasing computing power and new datasets from remote sensing platforms like LRO and the Shuttle Radar Topography Mission."
The lunar umbra is the part of the moon's shadow where the entire sun is blocked by the moon. On an eclipse map, this tells you where to stand in order to experience totality. For centuries, eclipse maps have depicted the shape of the moon's umbra, or darkest part of its shadow, as a smooth ellipse.
As evidenced in the new visualizations, the umbral shape is dramatically altered by both the rugged lunar terrain and the elevations of observers on Earth.
"We've known for a while now about the effects of the lunar limb and the elevation of observers on the Earth, but this is the first time we've really seen it in this way," Wright said. "I think it'll change how people think about mapping eclipses."
The true shape of the umbra is more like an irregular polygon with slightly curved edges. Each edge corresponds to a single valley on the lunar limb, the last spot on the limb that lets sunlight through. As these edges pass over mountain ranges, they are scalloped by the peaks and valleys of the landscape. The moon's umbra will cross the Cascades, Rockies and Appalachians during the 2017 eclipse.
"Solar and lunar eclipses provide an excellent opportunity to talk about the moon, since without the moon there would be no eclipses," said Noah Petro, deputy project scientist for LRO. "Because we know the shape of the moon better than any other planetary body, thanks to LRO, we can now accurately predict the shape of the shadow as it falls on the face of the Earth. In this way, LRO data sheds new light on our predictions for the upcoming eclipse."
The total solar eclipse on Monday, Aug. 21, 2017 will cross the continental United States beginning in Oregon and ending in South Carolina. The last time a total solar eclipse spanned the United States was in 1918, when the path of totality entered through the southwest corner of Washington and passed over Denver, Colorado, Jackson, Mississippi, and Orlando, Florida before exiting the country at the Atlantic coast of Florida.
For more information about the upcoming 2017 solar eclipse, visit: https:/
More information on the numerous NASA data sets incorporated into this visualization:
Blue Marble Next Generation was used for color of the land.
Shuttle Radar Topography Mission was used for Earth elevations. This is a global elevation map based on a radar instrument flown on Space Shuttle Endeavour during STS-99 in February 2000.
Lunar Digital Elevation Model and Selene/LRO Digital Elevation Model were used for the lunar limb.
NASA's Jet Propulsion Laboratory's DE421 provided Earth, moon, and sun positions.
Sarah Schlieder | EurekAlert!
Subaru Telescope helps pinpoint origin of ultra-high energy neutrino
16.07.2018 | National Institutes of Natural Sciences
Nano-kirigami: 'Paper-cut' provides model for 3D intelligent nanofabrication
16.07.2018 | Chinese Academy of Sciences Headquarters
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
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12.07.2018 | Event News
03.07.2018 | Event News
16.07.2018 | Physics and Astronomy
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To many people, viruses are simply agents for disease, but to Dr. Luis Villarreal, Director of the Center for Virus Research at the University of California Irvine, they may possess far greater power than originally thought.
He guides us through evidence that viruses gave rise to the first complex cells, played a role in the diversification of life, changed how our young are born, drove evolution, and perhaps gave us emotions. One expert even suggests that an ancient virus could have entered our genes and rewired us for monogamy. National Geographic investigates a provocative new theory that suggests that all life including humans is descended from viruses.
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Scientists at the University of York have shown that a sperm tail utilizes interconnected elastic springs to transmit mechanical information to distant parts of the tail, helping it to bend and ultimately swim toward an egg.
Previous studies, from approximately 50 years ago, showed that the sperm tail, or flagellum, was made up of a complex system of filaments, connected by elastic springs resembling a cylinder-like structure. For many years scientists believed that this system provided the sperm tail with a scaffold, allowing it to swim in a hostile environment toward an egg.
New research at the University of York, however, has shown, through a mathematical model, that this system is not only needed to maintain the structure of the tail, but it is also vital to how it transmits information to very distant parts of the tail, allowing it to bend and move in its own unique way.
Dr Hermes Gadêlha, mathematical biologist at the University's Department of Mathematics, said: "Sperm flagella with this sort of internal structure can be seen in almost all forms of life. Interestingly, although the sperm tail has an internal structure that is conserved across most species – animal and human - they all create slightly different movements in order to reach an egg.
"This suggests that the tail's structure is not the whole story to how they make their distinct tail-bending motion."
Dr Gadêlha and collaborators had previously developed a mathematical formula for the way in which sperm move rhythmically through fluid, creating distinct fluid patterns, but scientists now needed to understand what was going on inside the sperm tail that allowed them to move in this way.
To understand the structure of the tail, scientists examined how different parts of the tail bent by moving the tail of a dead sperm. Surprisingly a movement that started near the head of the sperm, resulted in an opposite-direction bend at the tip of the tail, called the 'counterbend phenomenon', suggesting that mechanical information is transmitted along the interconnected elastic bands in order to create movement along the full length of the tail.
Dr Gadêlha calculated these bending movements to form a mathematical model that would help hypothesize the triggers needed within the tail to make these distinct movements.
Dr Gadêlha said: "If we imagine that the communication to distant parts of the tail is a bit like the communication between blindfolded rowers in a canoe boat. Blindfolded rowers can't see each other's motion to communicate what movement to make, and in the absence of shouting to each other, they must instead feel the mechanics of the boat and the movement that each rower is making in order to synchronize their motion.
"It seems that the molecular motors - the 'rowers' inside the sperm tail - are doing a similar thing, but in a much more complex 'boat'.
"The mechanism of a sperm tail first creates a sliding motion between filaments, inside this cylindrically arranged structure, finally resulting in a tail bending, a bit like the piston that converts back and forth motion in to rotation of the wheel on a train. Any one movement in this complex sequence appears to be able to trigger motion right through to the distant parts of the tail.
"The big question now is, are particular springs in the tail coupled-up to transmit specific biomechanical information, and just are these 'rowers' self-organize?
The research is published in Journal of the Royal Society Interface.
Explore further: Mystery of how sperm swim revealed in mathematical formula
The counterbend dynamics of cross-linked filament bundles and flagella, Journal of the Royal Society Interface, rsif.royalsocietypublishing.or … .1098/rsif.2017.0065 | <urn:uuid:08887bf6-2c93-4853-a78b-1614d4b0be5f> | 4.09375 | 765 | News Article | Science & Tech. | 36.804903 | 95,548,086 |
Factors influencing incubation egg-mass loss for three species of waterfowl
Many bird eggs lose similar to15% of their fresh mass before pipping, but individual species have been reported to lose 10-23%. Most published estimates have been imprecise due to small sample sizes. Moreover, published estimates of within- or among-species variance components of mass loss are virtually unknown. We modeled the influence of nest type, clutch size, and egg size on daily mass loss of Mallard (Anas platyrhynchos), Common Goldeneye (Bucephala clangula), and Hooded Merganser (Lophodytes cucullatus) eggs and compared fractional mass loss among species. Mallard eggs in artificial nest cylinders lost more mass than those in ground nests, but were unaffected by nest initiation date. Average sized eggs in Mallard ground nests, Mallard cylinder nests, and Common Goldeneye and Hooded Merganser nest boxes lost 7.9 g (15.2%) 10.8 g (20.3%), 10.3 g (15.5%), and 9.2 g (15.8%) of fresh mass, respectively. For all species, daily mass loss increased as incubation progressed and was affected by an interaction between egg size and incubation time, but was not influenced by clutch size. Depending on species, smallest eggs lost 1.0-4.0% more of their fresh mass than did the largest. Egg-mass variability was partitioned into years, nests within years, and eggs within nests and years. Variability was evenly distributed among the variance components in Mallard ground nests; however, among-eggs within-nest variance predominated in nest cylinders. In contrast, among-nests variation was the dominant source for goldeneyes and mergansers. Nest-site selection and egg size likely involve trade-offs among optimum egg-mass loss and nest and hatchling survival
Zicus, M. C., Rave, D. P., & Riggs, M. (2004). Factors influencing incubation egg-mass loss for three species of waterfowl. Condor, 106(3), 506-516. | <urn:uuid:74872082-65a6-4a41-b822-1b6ae2f33db2> | 3.375 | 452 | Academic Writing | Science & Tech. | 58.442647 | 95,548,092 |
Описание книги Steps in Scala: An Introduction to Object-Functional Programming:
A hands-on introduction to Scala, the first fully-fledged programming language to embody the principles and ideas of object-functional programming. Highly expressive, concise and scalable, Scala grows to the needs of a programmer, whether professional or hobbyist. The book includes carefully chosen exercises and three full programming projects.
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Shining new light on quantum nonlocality effect
A team from Griffith's Centre for Quantum Dynamics in Australia have demonstrated how to rigorously test if pairs of photons - particles of light - display Einstein's "spooky action at a distance", even under adverse conditions that mimic those outside the lab.
They demonstrated that the effect, also known as quantum nonlocality, can still be verified even when many of the photons are lost by absorption or scattering as they travel from source to destination through an optical fiber channel. The experimental study and techniques are published in the journal Science Advances.
Quantum nonlocality is important in the development of new global quantum information networks, which will have transmission security guaranteed by the laws of physics. These are the networks where powerful quantum computers can be linked.
Photons can be used to form a quantum link between two locations by making a pair of photons that are "entangled" - so that measuring one determines the properties of its twin - and then sending one along a communication channel.
Team leader Professor Geoff Pryde said a quantum link had to pass a demanding test that confirmed the presence of quantum nonlocality between particles at either end.
"Failing the test means an eavesdropper might be infiltrating the network," he said.
"As the length of quantum channel grows, less and less photons successfully pass through the link, because no material is perfectly transparent and absorption and scattering take their toll.
"This is a problem for existing quantum nonlocality verification techniques with photons. Every photon lost makes it easier for the eavesdropper to break the security by mimicking entanglement."
Developing a method to test entanglement in presence of loss has been an outstanding challenge for the scientific community for quite some time.
The team used a different approach - quantum teleportation - to overcome the problem of lost photons.
Dr Morgan Weston, first author of the study, said they selected the few photons that survived the high-loss channel and teleported those lucky photons into another clean and efficient, quantum channel.
"There, the chosen verification test, called quantum steering, could be done without any problem," she said.
"Our scheme records an additional signal that lets us know if the light particle has made it through the transmission channel. This means that the failed distribution events can be excluded up front, allowing the communication to be implemented securely even in the presence of very high loss."
This upgrade doesn't come easy - the teleportation step requires additional high-quality photon pairs on its own. These extra photon pairs have to be generated and detected with extremely high efficiency, in order to compensate for the effect of the lossy transmission line.
This was possible to achieve thanks to state of art photon source and detection technology, jointly co-developed with the US National Institute of Standards and Technology in Boulder, Colorado.
Although the experiment was performed in the laboratory, it tested channels with photon absorption equivalent to about 80 km of telecommunications optical fiber.
The team aims to integrate their method into quantum networks that are being developed by the Australian Research Council Centre of Excellence for Quantum Computation and Communication Technology, and test it in real-life conditions.
Sergei Slussarenko | 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
17.07.2018 | Materials Sciences
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Image: Jon Lomberg
Astronomers using the Gemini North Telescope on Hawaii’s Mauna Kea report that they have created a three-dimensional movie of a powerful, active galaxy located some 70 million light years away. The addition of a new instrument, the Integral Field Unit (IFU), to the Gemini telescope enabled the group to study light from the galaxy NGC1068 in much greater detail. From a single still of NGC1068, the IFU generated data on the physical conditions and velocities of galactic material throughout the image. This information, in turn, allowed the astronomers to create an animated picture that provides a fresh look at the workings of the galaxy, including an enormous pair of jets bursting out of a suspected black hole at its core. Two reports on these findings will appear in the Conference Series of the Astronomical Society of the Pacific.
The benefit of using the advanced Gemini telescope, the scientists say, stems from its capacity for capturing and refining light. In this case, the IFU transmits the enormous volume of light collected by Gemini through hundreds of tiny optical fibers, each of which bears a micro-lens at its tip. The optical fibers send the light to an advanced spectrograph, which produces a single spectrum for each fiber--1500 in all. From that data, the researchers can describe and track the motions of gas or stars at any point in the image. "When we play back our movie of the galaxy NGC1068, we see a three-dimensional view of the core," says Bryan Miller, the Gemini instrument scientist for IFUs. Of particular interest are the two jets that extend out from the galaxy’s center. Gemini scientist Jean-Rene Roy compares the shockwave-type effect the enormous jets inflict on the galaxy’s surrounding gaseous disk to that of "a huge wave smashing onto a galactic shoreline."
More advanced IFUs may provide better images still. Within the next two years, for instance, new optical and near-infrared IFUs will be used on both Gemini North and a sister telescope in Chile. These new systems should produce some of the highest resolution images obtainable by telescopes, enabling astronomers to study in even closer detail the dynamics of distant galaxies.
Greg Mone | Scientific American
What happens when we heat the atomic lattice of a magnet all of a sudden?
18.07.2018 | Forschungsverbund Berlin
Subaru Telescope helps pinpoint origin of ultra-high energy neutrino
16.07.2018 | National Institutes of Natural Sciences
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
18.07.2018 | Materials Sciences
18.07.2018 | Life Sciences
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Flash Programming for the Social & Behavioral Sciences (BOK)
Sendes vanligvis innen 7-15 dager
Adobe Flash is one of the most popular languages for animated web content, and recently social and behavioural scientists have started to take advantage of it to collect data online. This book is a unique, step-by-step guide to using Adobe Flash to develop experiments and other research tools. Each chapter presents a set of techniques required for one aspect of programming an experiment, with students following instructions in italics and working through the code included in the text. Most chapters end with an exercise to put the newly learned techniques into practice. No previous knowledge of programming is required, though general computer literacy is assumed. Basic programming principles are introduced throughout the book in the context of solutions to specific research problems. | <urn:uuid:1e2f7d52-ca97-401e-94e7-101f074626f7> | 3.140625 | 164 | Product Page | Software Dev. | 25.937826 | 95,548,142 |
A new catalyst material developed by chemists at MIT provides key insight into the design requirements for producing liquid fuels from carbon dioxide, the leading component of greenhouse gas emissions. The findings suggest a route toward using the world’s existing infrastructure for fuel storage and distribution, without adding net greenhouse emissions to the atmosphere.
The new catalyst takes the process only through its first stage — converting carbon dioxide (CO2) to carbon monoxide (CO), explains assistant professor of chemistry Yogesh Surendranath, the senior researcher on a new study describing the advance. But that’s a key initial step toward converting CO2 to other chemicals including fuels, he says; there are already established methods for converting CO and hydrogen to a variety of liquid fuels and other products.
The study appears this week in the international chemistry journal Angewandte Chemie. Its authors are Youngmin Yoon, a graduate student at MIT; Anthony Shoji Hall, a former MIT postdoc who is now a professor of materials science at Johns Hopkins University; and Surendranath, who is the Paul M. Cook Career Development Assistant Professor at MIT.
“The problem in CO2 conversion is how to selectively convert it,” Surendranath says.
While this basic molecule can form the basis of virtually any carbon-based chemistry, the tricky part is to create a system in which CO2 consistently converts to a single end-product that can then be further processed into the desired material. The new system, he says, provides just that kind of selective, specific conversion pathway — and, in fact, a whole range of such pathways. And if the hydrogen and CO are produced using solar or wind-generated power, the entire process could be carbon neutral.
“What you want is a tunable catalyst,” he says, and that’s just what this team developed, in the form of a highly porous silver electrode material. Depending on the exact formulation of this material, he says, it’s possible to design variations of this catalyst where “each one may be designed for a different application.”
The researchers learned that by tuning the dimensions of the material’s pores they could get the system to produce the desired proportion of CO in the end-product.
Most efforts to “tune” the selectivity of silver catalysts for CO production have focused on varying the surface active site chemistry. However, with this formulation, a material called a silver inverse opal, it is the pore structure of the material that determines the effect. “What we found was very simple,” Surendranath says. “You can tune the pore dimensions to tune the selectivity and activity of the catalyst, without modifying the surface active site chemistry.”
The porous material can be made by depositing tiny polystyrene beads on a conductive electrode substrate, then electrodepositing silver on the surface, then dissolving away the beads, leaving pores whose size is determined by that of the original beads. Because of the way spheres naturally organize themselves when packed together, this method produces a honeycomb-like structure of hexagonal cells, Surendranath explains.
It turns out that varying the thickness of this porous catalyst produces a double effect: As the porous inverse opal get thicker, the catalyst more strongly promotes the production of CO from CO2 by up to three times, while also suppressing an alternative reaction, the production of H2 (hydrogen gas), by as much as tenfold. Using this combined effect, production of CO can be easily varied to make up anywhere from 5 to 85 percent of the reaction’s output. The study’s results provide fundamental insights that may be applicable to designing other catalyst materials for fuel production from CO2.
This advance represents just one step in the conversion of carbon dioxide into usable fuels, and the initial demonstration is just at a small laboratory scale. So, much work still remains for this to become a practical approach to manufacturing transportation fuels. But because the selectivity and efficiency of this initial conversion step places an upper limit on the overall efficiency of fuel production from CO2, in technical terms, Surendranath says, the work provides key fundamental insight into how to engineer carbon-neutral technologies for replacing existing fossil-fuel systems — while still being able to use all of the existing infrastructure of gas stations, delivery vehicles, and storage tanks.
Ultimately, conversion plants could be connected directly to the emissions flow from fossil-fuel power plants, for example, to turn the CO2 into fuel instead of releasing it into the atmosphere at all. “We’re very optimistic” that the process can be successfully developed, Surendranath says. If so, that could represent “the closing of the anthropogenic carbon cycle,” through the use of renewably generated electricity to turn greenhouse gas emissions into fuel.
In essence, he says, the net process would be doing the same thing that plants and cyanobacteria did on Earth millions of years ago to produce fossil fuels in the first place: taking carbon dioxide out of the air and converting it into more complex molecules. But in this case, instead of taking place over millennia, the process needs to be replicated very quickly in a lab or factory. “It’s the same thing that got us these fuels in the first place,” he says, “but we need to do it faster and more efficiently than natural photosynthesis.”
This paper could have “huge impacts on the basic science of important reactions to produce fuels,” says Ken Sakaushi, a researcher at the National Institute for Materials Science in Tsukuba, Japan, who was not involved in this research. “Recently, many works just focus on the application side and thus make less of a contribution on basic science. However, this work seems to try to contribute to this important issue on science from the basics.” Because of that, this research has “high value,” he says.
The research was supported by the Air Force Office of Scientific Research and the MIT Department of Chemistry, and is part of the research taking place through the MIT Energy Initiative’s Low-Carbon Energy Centers, established as part of the Institute’s Plan for Action on Climate Change.
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Latest posts by H. Sterling Burnett (see all)
- Paris Climate Participants Miss Targets While U.S. Reduces Its Emissions - July 12, 2018
- Pope Francis’s Misguided War on Fossil Fuels - July 6, 2018
- Climate Fight Loses a Warrior - July 1, 2018
Two quite different climate science stories caught my eye this week, below is a sampling of both.
A paper in Chemosphere finds a little-discussed benefit of the effect of increased carbon dioxide on plant growth: At higher levels of carbon dioxide, plants remove greater amounts of toxins from the soil and at a faster pace. Soil contamination by heavy metals, including cadmium and lead, is a serious problem in many parts of the world. In China, it is estimated more than 20 million hectares of land are contaminated.
In controlled tests, the Chinese researchers involved in the study sowed black locust seeds in pots in open-top chambers maintained under ambient carbon dioxide levels of 385 parts per million (ppm) or elevated levels of 700 ppm. At 30-day intervals, 30, 60, and 90 days after the locust seeds sprouted, the researchers collected samples from each treatment. They found black locust grown under higher carbon dioxide levels were “associated with greater removal of heavy metals from … soils relative to ambient CO2 … [with] improvements in the microenvironment suggest[ing] that elevated carbon dioxide could benefit soil fertility … under heavy metal stress.”
That is: The plants studied remove from the soil greater amounts of toxins under conditions of elevated carbon dioxide levels, thus improving the soil’s fertility – its ability to grow crops and other useful plants suppressed under conditions of high heavy metal contamination.
In 2016 the U.K.’s Guardian reported on a survey led by researchers at George Mason University’s Center for Climate Change Communication concerning the views of broadcast meteorologists on climate change and humanity’s role in it. The lead author of the survey was Edward Maibach, one of 20 academics who signed on to a letter to U.S. Sen. Sheldon Whitehouse arguing climate skeptics should be prosecuted for racketeering.
Nearly all weathercasters who responded to the 2016 survey said they believe climate change is happening, although just 67 percent said they thought humans were responsible for most climate change.
This year’s version of the survey by the same group shows the percentage of meteorologists certain humans are causing climate change to have fallen precipitously in the last year. Between 2016 and 2017, the number of broadcast meteorologists who responded to the survey and said they believe humans have caused most or all of the present climate changes fell from 67 percent to less than half, only 49 percent. In 2017, only 15 percent of the meteorologists responding to the survey thought climate change was largely or entirely man-made, falling from 29 percent in 2016. Twenty-one percent of respondents think climate change is more or less equally caused by human activity and natural events, while another 21 percent think climate change has been primarily or entirely due to natural events.
There are many other interesting finding’s in the survey and I encourage interested readers to peruse it at their leisure and perhaps to even read Australian science writer Jo Nova’s take on import of the two years survey’s differing findings.
Not surprisingly, considering it’s decidedly leftist, alarmist slant, The Guardian failed to report on this years survey. Among broadcast meteorologists, there never was a 97 percent consensus humans are causing dangerous climate change, and evidently even that tide is turning. Today, not even a majority of them support that view. If the views of broadcast meteorologists are any indication, the forces of climate realism are rising. | <urn:uuid:ccbfb7be-c68f-45c7-8fa3-1057ed3a38a1> | 2.9375 | 774 | Personal Blog | Science & Tech. | 39.72129 | 95,548,215 |
Coral Reef Awareness Week, in the third week of July each year, was created to highlight the importance of coral reefs and the need to protect them. Coral reefs only cover 0.2 percent of the ocean floor, but these amazing ecosystems support around 2 million species of marine plants and animals. In addition, more than 500 million people throughout the world rely on coral reefs for food and income.
Coral reefs have been on the earth for about 500 million years. But in the past few decades, coral reefs have been dying at an alarming rate. It?s estimated that 19 percent of the world?s coral reefs are already dead, and 60 percent are currently at risk. If global action is not taken to stop this decline, all coral reefs will be in danger by 2050.
You may have heard about how sunscreen can be toxic to coral reefs, but many other factors also impact the health of coral reefs. Let?s look at some of the worst threats coral reefs currently face.
1. Climate Change
Research suggests that climate change is quickly becoming the most significant threat to coral reefs today.
A coral reef is actually a community of hundreds to thousands of corals, which are small, delicate animals that are easily disrupted by changes in their environment. Each tiny, soft-bodied coral secretes a hard outer skeleton of limestone to keep itself safe. The accumulation of these skeletons creates a coral reef.
This process has been going on uninterrupted for thousands of years and has created the massive coral structures we know today. But corals also form an incredible partnership with a type of algae known as zooxanthellae to keep this cycle going. Zooxanthellae are single-celled algae that can live within the corals? soft tissues, where they photosynthesize in a way similar to plants. The corals can then feed off the products of the algae?s photosynthesis and continue to grow and thrive.
It?s been observed that a rise in ocean temperatures of only one or two degrees can disrupt this unique partnership. When oceanwater heats up, the zooxanthellae start producing toxins, which forces the corals to eject the algae back into the ocean. Without the zooxanthellae, corals lose a vital food source and slowly die. This process is known as coral ?bleaching? because the colorful, living algae and corals are gone, leaving only the white limestone skeletons behind.
Climate change is causing a rise in overall ocean temperatures, as well as increasing the likelihood of localized temperature spikes. A chilling example of this was a ten-month long stretch of abnormally warm water around Christmas Island in the Indian Ocean from July 2015 to April 2016. In the months following the temperature spike, 90 percent of the reef?s corals died.
Another deadly trend fueled by climate change is ocean acidification. Every day, 90 million tons of carbon pollution is released into our atmosphere. About one-third of that carbon is absorbed by our oceans, which is gradually altering the chemistry of seawater and making it more acidic. The chemical changes make it more difficult for corals to acquire the nutrients they need to survive, causing a slower decline than bleaching, but with a similarly fatal end.
Global demand for fish continues to increase, both for food and for the pet trade. Over-harvesting of fish to meet this demand is taking a toll on biodiversity and the ecological balance of coral reefs. Physically damaging fishing methods, such as trawling or using dynamite or cyanide in the water, can also damage or completely destroy coral reefs.
Pollution affects our entire planet, including our oceans. A 2013 study found that fine airborne particles, produced largely by human industrial activities, actually block sunlight from reaching corals, which impacts photosynthesis and growth. Researchers examined coral reefs in Panama and Belize and found their growth rates have been slowing down since the 1950s because of this reduction in sunlight.
In addition, the 8 million tons of plastic that enter the world?s oceans each year disrupt countless numbers of marine plants and animals, including corals, who will eat tiny plastic pieces thinking they?re food. Many other sources of pollution, such as oil spills, sewage and agricultural runoff, also take a toll on coral reefs.
4. Human Activities
Irresponsible human recreation, such as careless swimming, snorkeling or diving, can damage coral reefs. Boating can also hurt coral reefs through noise pollution, dropping anchors on sensitive areas or collisions with wildlife.
Human coastal development is another threat. Sensitive marine areas are being dredged and disturbed to construct airports and buildings on land reclaimed from the sea. Also, building marinas, fish farms and other water-based structures can disrupt nearby coral reefs.
The frequency of coral disease appears to be on the rise, primarily by infection from bacteria, fungi or viruses. Scientists believe this is largely due to the increased environmental and physical impacts corals are currently facing, which weakens their natural defenses.
For example, an Australian study looked at the effect of permanent offshore visitor platforms that had been constructed within the Great Barrier Reef Marine Park. Researchers found that coral disease was up to 18 times more likely in reefs with platforms compared to undisturbed reefs.
WHAT YOU CAN DO TO HELP CORAL REEFS
The World Resources Institute has a great video summarizing their Reefs at Risk report, which examined the state of the world?s coral reefs and what we can do to bring them back to health. Check it out below.
Related on Care2
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How You Can Help Protect the World?s Wildlife
10 Surprising Facts About Turtles
Disclaimer: The views expressed above are solely those of the author and may not reflect those of Care2, Inc., its employees or advertisers.
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*Originally posted in January 2015 on www.thereremouse.com
Hi All! I have been working this week on the 2nd edition of the Bees of Walsall, which will be out 2016. There are loads more sites, many more species, and several new chapters. I thought I’d give you an idea of what I’m working on. Here’s the new chapter on scientific nomenclature – so if the scientific names of species is all Greek to you, you might enjoy this:
“You’ll see as you go through this book (and you may have noticed on websites and in field guides), a common name for a bee (i.e. Tree Bumble Bee) followed by two latin or greek words in italics (i.e.Bombus hypnorum). This is called a binomial. It is also sometimes called a ‘latin name’ (although it is not always latin – often greek or a derivation of the name of the naturalist who discovered the species) or a ‘scientific name’ and it is part of the way in which scientists classify organisms. In printed text the binomial will always be in italics; in hand written text it is usually underlined (this is just taxonomic etiquette, but a useful habit to get into).
The first of these two words is the Genus, which is the group of animals to which the organism belongs. If you see ‘Bombus‘ this means you are looking at a bumble bee. The second word refers to the species. A species is (generally – there are some exceptions) an animal that can only produce viable offspring with another of its kind. So a horse and a donkey are different species because, although they can reproduce, their offspring (mules) are infertile; but they ARE both in the same genus.
Sometimes you will see three names rather than two – this means that it is referring to a subspecies (i.e. Wolves are Canis lupus; domestic dogs are Canis lupus familiaris.
You might wonder why we bother, and why we don’t just use common names. There are two main reasons for this – firstly, the binomial lets us know instantly how an animal relates to other animals without having to look it up, and secondly, it transcends international changes in common names. One example of this is the group of birds called ‘buzzards’. In the United States these are called ‘hawks’, which can be confusing as here we have ‘sparrowhawks’ which are not in the same genus. Calling this group of birds by their genus: ‘Buteo‘ lets us know that, for example, the American ‘Red Tailed Hawk’ is more closely related to our ‘European Buzzard’ than to the ‘Sparrowhawk’, even thought the common names would imply the opposite.
As you do more reading you will see binomials shortened: ‘B. hortorum‘ instead of ‘Bombus hortorum‘. This is almost always done AFTER the full genus has been mentioned, and it is a generally accepted shorthand in natural history texts. However it wouldn’t be right to talk about Andrena fulva (Tawny Mining Bee) and then shorten Apis mellifera (Honey Bee) to A. mellifera as it can be confusing.
In addition, you may see the genus followed by ‘sp.‘ or the plural ‘spp.‘ – this stands for ‘species’. The ‘sp.’ is singular, and is used, for example, when referring to an unidentified species: “I’m not sure what this bee is; probably an Andrena sp.” Alternatively, if you see the plural ‘spp.‘ after the genus, it means that it is referring to more than one species in this genus: “Megachile spp. carry their pollen on their abdomen while Andrena spp. carry pollen on their legs.”
The other thing you may encounter is that entomologists have ‘pet names’ for species. For example, you might hear someone say ‘I found a HUGE hortorum nest today!’. They are referring to Bombus hortorum (The Garden Bumble Bee), but as there are no other common species called ‘hortorum‘, this is a generally accepted way to shorten it. Having said that, you WOULDNT say ‘I saw a beautiful humilis today!” because there is both a Bombus humilis and an Andrena humilis. (I know it’s confusing at first, but I promise you’ll get the hang of it – a good way to start is to try to learn one group of bees at a time, and you’ll remember the binomials more easily.)
One last thing on the subject of nomenclature – the names change! All the time! While this causes a good deal of eye rolling in the field, and can be confusing, it is a necessary part of the process. As we learn more about species and about their relationships with other species, scientists often correct the binomials to keep up with modern taxonomic knowledge. A huge example of this in the Bee world is the change in 1994 of the genus name ‘Psithryus‘. This used to be the name for the genus of Cuckoo Bumble Bees – there are 29 species in the world (six species in the UK). But they are now regarded as being in the genus ‘Bombus‘ along with other bumblebees, with ‘Psithryus‘ being considered a subgenus (a subset) of ‘Bombus‘. The ‘Psithryus’ part is not usually written in the binomial, but if it is, it is written like this: ‘Bombus (Psithryus) rupestris‘.
Sometimes this only happens to a specific species – the Red Mason Bee (Osmia bicornis – so named for the two horns on the face of the female) used to be called ‘Osmia rufa‘. This change is so recent that many entomologists still talk about ‘Osmia rufa‘ in the field. This happens sometimes due to the discovery or acknowledgment of an original type specimen or description:
For example, the dinosaur Brontosaurus doesn’t exist! The species was described in 1879 by O.C. Marsh and named ‘Brontosaurus‘ (its actually quite a hilarious story and worth Googling). It was later discovered that the specimen was the same species as one he had described and named two years earlier: Apatoaurus. In science, the earliest description of a specimen is always considered the genuine one, so the Dinosaur books had to be re-written!
You may occasionally see a name and date written after a species – this refers to the person who first described and named the species (Called the ‘authority’), and the date in which they did so. So you could see the Red Tailed Cuckoo bee written as either ‘Bombus rupestris‘, ‘Bombus (Psithryus) rupestris‘, ‘Bombus rupestris (Fabricius, 1793)’ or ‘Bombus (Psithryus) rupestris (Fabricius, 1793)’ – but they all refer to exactly the same species.
Another post-script to binomials is the ‘sensu scripto / sensu lato’ addendum. These two phrases are sometimes appended to the binomial of an organism to indicate how loosely the identification is intended. ‘Sensu scripto’ (also written ‘sens. scr.’ or ‘s.s.’) means ‘strictly speaking’ and ‘sensu lato’ (also written ‘sens. lat.’ or ‘s.l.’) means ‘loosely speaking’.
For example the White Tailed Bumble Bee, Bombus lucorum is actually part of a group of species which cannot be readily separated (Bombus lucorum, Bombus cryptarum and Bombus magnus). As a result, it is often recorded as ‘Bombus lucorum sensu lato’, which indicates that you are acknowledging that it is part of this group but you cannot tell which of the group it is. Another way of thinking about ‘sensu lato’ is that it means “Including all its related and sub-species which are usually considered as separate”.
A great deal of emphasis is placed on accuracy in biological recording. One of the main principles is not recording anything unless you are SURE which species you have identified. ‘Sensu lato’ allows us to record the White Tailed Bumble Bee without dissecting it!
I hope this helps you wade through the muddle of scientific nomenclature. Taxonomy and cladistics is a dynamic field of study, and we must all adjust in the name of greater accuracy and scientific knowledge.”
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In this chapter, you looked at ways to pass information to Ant so that it can perform actions based on that information. Many of the build file elements described are information aggregators that group file and directory names according to patterns. In other words, they collect information on the files and directories you want to use. Once this information has been gathered, Ant passes it to the tasks so that they can carry out their functions.
You can select files in many ways; the first way you looked at was patterns. Ant uses the standard wildcard characters (* and ?) and introduces the ** operator that tells Ant to expand directory structures. These operators are powerful in combination and make working with files much easier.
Ant provides you with a set selectors that you can use to further refine your selection criteria. They allow you to select files and directories based on physical properties, such as size and date of modification, rather than just on name.
KeywordsDirectory Structure Base Directory Core Task Child Element Pattern Segment
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Spectral Characteristics of Radiation and Matter
The wave nature of radiation is responsible for many interesting and unique phenomena involving the interaction of radiation and matter. Prisms, gratings, and other devices disperse radiation into many types of spectrums, classified according to the techniques used for their detection or generation. The wavelength regions have historical names related to scientific discovery and development of the particular spectral interval. There are, for example, gamma rays, x-rays, ultraviolet radiation, visible light, and infrared, microwave, and radio wave radiation. Smaller wavelength intervals within these broad spectral regions have also been given names.
KeywordsSolar Radiation Spectral Property Spectral Distribution Spectral Reflectance Color Match
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Their study -- appearing online ahead of regular publication in the journal Behavioral Ecology and Sociobiology -- provides a glimpse of nature's way of providing for its displaced workers.
"This study demonstrates an advantage of social living that we are familiar with -- humans that can no longer do certain tasks can still make very worthwhile contributions to society, even if they could not live on their own," said the paper's lead author Robert Schofield, a scientist at the University of Oregon.
“While division of labor is well documented in social insects, this is the first suggestion that some social insects stop performing certain tasks because they are no longer as good at them as they used to be. As social organisms, these ants have the luxury of being able to leave the cutting task to their more efficient sisters.”
Leaf-cutter ants slice leaves, carry pieces back to the underground nest for further processing and, like tiny mushroom farmers, grow an edible fungus on the resulting substrate. The ants doing the cutting are usually members of the generalized forager caste, one of four size-based behavioral castes of workers. The foragers are second in size to the majors, the large workers that protect the colony and do heavy clearing work on the trails constructed to connect the nest to the leaf sources. In addition to cutting, the foragers transport the cuttings, scout for new resources and also help protect the colony.
"Cutting leaves is hard work. Much of the cutting is done with a V-shaped blade between teeth on their mandibles that they use like a tailor who holds a pair of scissors in a fixed V shape to slice through cloth," Schofield said. "This blade starts out as sharp as the sharpest razor blade that humans have developed."
Over time, though, their mandibles slowly dull. It takes longer and requires more energy to get the job done. When it takes an ant about three times as much time and energy to cut out a leaf disc than it would have taken when her blades were sharp, behavior changes, the researchers reported. The cutting ants rest their blades and join the delivery staff, carrying the discs cut from the leaves into their nest.
"Imagine having only two tiny knives to use for your entire life, with no sharpening allowed," Schofield said. "You would want them to be made of the best material possible. You would use them very carefully, but cutting would still get harder and harder as they dulled until you had to rely on others to cut for you. That’s what it is like to be a leaf-cutter ant."
The composition of the cutting blades is of particular interest to researchers. The findings support the idea that wear and fracture are big problems for smaller animals. The researchers estimate that, because of wear, the colony spends twice as much energy cutting leaves as it would if all ants had sharp mandibles. This cost should have resulted in an evolutionary pressure to develop materials that resist dulling, the research team noted. The cutting blades are indeed made of a zinc-rich biomaterial that the researchers suspect is wear resistant.
Schofield was lead author of a study published in 2001 that had identified a family of biomaterials present in mandibular teeth, tarsal claws, stings and other such tools of small organisms. In 2009, a team led by Schofield reported that a similar type of substance empowers the claw tips of striped shore crab and is present on the walking legs of Dungeness crabs.
"Humans are just starting to try to engineer tiny machines and tools, and we have a lot still to learn from organisms that have coped with being small for millions of years," Schofield said. “And in addition, it’s good to know how important wear is to these ants, because they are agricultural pests, and this research hints that crops that produce high levels of wear might discourage them.”
A four-member team of researchers from the UO and Oregon State University conducted the new study. With support from the National Science Foundation, the team studied a colony of the leaf-cutter ants (Atta cephalotes) from the Soberania National Park, near Gamboa, Panama. Leaf-cutter ants range from the southern United States through South America.
Co-authors with Schofield were Kristen D. Emmett and Jack C. Niedbala, UO undergraduates at the time of the project, and Michael H. Nesson of OSU's department of biochemistry and biophysics.About the University of Oregon
Contact: Jim Barlow, director of science and research communications, 541-346-3481, firstname.lastname@example.org
Source: Robert Schofield, senior research associate, department of physics, 541-346-4783, email@example.com
UO Physics Department: http://physics.uoregon.edu/
VIDEO-1: http://www.youtube.com/watch?v=FMsqTRCHHWI (View from below: Cutting is done by the proximal blade of the distal (first tooth) as the tooth rides along the surface. Ants are seen cutting Rubus armeniacus leaves initially and then Prunus lusitanica leaves. Copyright: Robert Schofield.)
VIDEO-2: http://www.youtube.com/watch?v=VqOsOWjlKQs (View from above of laboratory colony ants, Atta cephalotes, cutting leaves. The leading mandible is often used to partially cut through the leaf in advance of the lagging mandible, and is used as an anchor to pull the lagging mandible against in order to complete the partial cut. Copyright: Robert Schofield.)
VIDEO-3: http://www.youtube.com/watch?v=gX_8OkxF1Yk (Two laboratory colony ants, Atta cephalotes, with highly worn mandibles appear to be having difficulties cutting Prunus lusitanica leaves. The second clip shows a second ant cutting with blunted teeth in a view from below. Copyright: Robert Schofield.)
Jim Barlow | Newswise Science News
Innovative genetic tests for children with developmental disorders and epilepsy
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Oxygen loss in the coastal Baltic Sea is “unprecedentedly severe”
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A new manufacturing technique uses a process similar to newspaper printing to form smoother and more flexible metals for making ultrafast electronic devices.
The low-cost process, developed by Purdue University researchers, combines tools already used in industry for manufacturing metals on a large scale, but uses...
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"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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Wallace J. Nichols, P. Dutton, J.A. Seminoff, E. Bixby, F.A. Abreu-Grobois, and A.R.S. Hidalgo. 2000. Poi or papas? Do Hawaiian and Mexican green turtles feed together in Baja California waters. In: Kalb, H.J. and T. Wibbels, compilers. Proceedings of the Nineteenth Annual Symposium on Sea Turtle Biology and Conservation. U.S. Dept. Commerce. NOAA Tech. Memo. NMFS-SEFSC-443, 291 p.
Black turtle (Chelonia mydas agassizii) foraging grounds along the coasts of Baja California, Mexico (Fig. 1) were surveyed during 1996-1998. 92 tissue samples were collected and analyzed using standard molecular genetic methods. Haplotypes from feeding areas were compared to those known from nesting populations in the eastern and central Pacific (Dutton et. al., unpublished data). Results suggest that Baja California’s Chelonia originate from several disparate nesting areas. The majority of the haplotypes found on foraging grounds are of the Michoacan type (80%), however approximately 20% were not.
Hypotheses for the origin of these turtles include dispersal from Hawaiian rookeries (6% were haplotype D; Dutton’s nomenclature) or the Islas Revillagigedos, a small archipelago off of the coast of Colima, Mexico. As genetic samples have not yet been obtained from the Islas Revillagigedos we recommend doing so. The hypothesized “Revillagigedos” haplotype (G; Dutton’s nomenclature) was significantly more abundant along the Pacific coast when compared to Gulf of California feeding grounds, supporting pelagic dispersal from the archipelago to the feeding grounds on the west coast of Baja California.
Supporting information from tagging and satellite telemetry reiterate the conclusion that a majority of Baja California Chelonia originate from and return to nest in Michoacan, Mexico. Three adult female turtles were tracked using satellite telemetry from Gulf of California feeding grounds to the vicinity of Colola, Michoacan. Each of the three turtles had “Michoacan” haplotypes (E,E, and N; Dutton’s nomenclature). All tag returns from Baja California feeding grounds have been from Colola or Maruata, Michoacan. None of the 250+ turtles tagged by this project have been found on any nesting beach other than those in Michoacan.
These results represent the first efforts to define management units for the east Pacific green turtle, a population that continues to decline despite nearly three decades of conservation efforts on its principal nesting beaches in Michaocan (Alvarado, pers. comm.). They also represent the first black turtles ever tracked from feeding to nesting areas, a distance of approximately 2000 km. Further, these results suggest that high mortality rates of large subadult and adult Chelonia on feeding grounds have likely played a significant role in the slow recovery of several eastern Pacific rookeries.
Recent research has confirmed what many boaters already know – you experience emotional, behavioral... continue
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The audience is first presented with an overview of the issue at hand. Excessive carbon dioxide gas in our world's atmosphere is causing negative repercussions for all biological life.
This is followed by informing them that a developmental science known as air capture technology could potentially fix the problem.
One of the possibilities with air capture tech is the ability to engineer carbon dioxide emissions into carbonate bricks. This fact is emphasized through the usage of Lego bricks in the exhibit.
An accompanying book served the purpose of providing the audience with more information and scientific research about the issue.
Carbon dioxide molecule magnets were constructed out of Legos for the audience to take home. Using Lego pieces to make this item further reinforces the idea of carbonate bricks.
If you'd like to learn more please visit The Center for Negative Carbon Emissions' website for info on air capture technology. | <urn:uuid:7404be23-d71a-4750-9dc8-3b1551ff7454> | 3.515625 | 173 | Knowledge Article | Science & Tech. | 28.841462 | 95,548,286 |
Six so called spherical viruses (four plant and two animal) are shown to exhibit magnetically induced birefringence in solu-tion. They must therefore be magnetically and optically anisotropic. This is attributed to static structural anisotropy of the interiors as neither natural shape nor field-induced deformations are likely causes. Thus at least part of these virus cores have a symmetry differing from that of their cap-sids. An estimate of the average orientation of the RNA bases is given for the plant viruses: turnip yellow mosaic, bromegrass mosaic, tomato bushy stunt and turnip crinkle. The packing geometry of the nucleic acid/protein cores of adenovirus and probably influenza virus are anisotropic but to an extent that cannot be quantified. Key words: adenovirus/influenza virus/magnetic birefrin-gence/plant virus/virus internal structure Introduction Magnetically induced birefringence has previously been us-ed to investigate the solution behaviour and structure of two flamentous bacteriophages Pfl and fd (Maret et al., 1979; Torbet and Maret, 1981). Consequently, highly oriented fibres, which gave improved X-ray diffraction patterns, were formed by partial drying in a magnetic field (Torbet and Maret, 1979). This technique was subsequently developed and exploited for detailed structural studies (Nave et al., 1979, 1981; Banner et al., 1981). This paper is an extension of that work to the study of the spherical viruses listed in Table I. The four plant viruses (Table I) each contain single-stranded RNA encapsidated in a T = 3, 180 protein subunit icosahedron. Electron microscopy has revealed little about the RNA structure in small plant viruses. This is also true of X-ray crystallography which, however, has detailed the struc-ture of much of the protein of three viruses (Harrison et al., 1978; Abad-Zapatero et al., 1980; Unge et al., 1980). Most of the information which is summarized below on the disposi-tion of protein and nucleic acid has been obtained from neutron scattering (reviewed by Jacrot, 1981). In turnip yellow mosaic virus (TYMV) the protein forms a very dense shell and is hardly penetrated by the RNA which is distributed throughout the interior (Jacrot et al., 1977). The protein of bromegrass mosaic virus (BMV) capsid is not very densely packed and is interpenetrated to a limited extent by RNA which is localized into a narrow sheet (Jacrot et al., 1977; Chauvin et al., 1978a). In tomato bushy stunt virus (TBSV) the protein subunit has two domains, one is closely packed on the surface, the other extends inwards into the RNA shell and there is a central cavity which is smaller than that in BMV (Chauvin et al., 1978b; Harrison et al., 1978). Both the N-terminal part of the protein subunits and the RNA are believed to be spatially disordered because they do not give rise to clear features in high resolution electron density maps (Harrison et al., 1978). No neutron scattering results have been published on the structure of turnip crinkle virus (TCV) but it is expected to be very like TBSV (Munowitz et al., 1980). Thus apart from the latter two these plant viruses have significant differences in their protein-RNA interactions and distribution. Measurements are also reported on two spherical animal viruses, adenovirus and influenza virus. The former has an icosahedron (T = 25) capsid which is composed of three ma-jor structural proteins. The core contains double-stranded DNA in association with four species of protein. The nucleo-protein may be in the form of folded rods (Nermut, 1979) with a structure akin to chromatin (Corden et al., 1976; Mirza and Weber, 1982). The outer envelope of influenza virus, recently shown to be spherical in solution (Mellema et al., 1981), is a lipid bilayer from which project two types of glycoprotein. It has a segmented RNA genome and the eight segments are believed to interact with the protein in the core to form a regular double-helical structure (Compans et al., 1972). In general, because it has proved to be a difficult prob-lem to approach experimentally, little is known about the packing geometry of the cores in most spherical viruses. Here it is demonstrated that the internal symmetry of spherical viruses can differ from that of their exteriors.
Mendeley saves you time finding and organizing research
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- Nano Express
- Open Access
Nanofluid optical property characterization: towards efficient direct absorption solar collectors
© Taylor et al; licensee Springer. 2011
Received: 31 October 2010
Accepted: 15 March 2011
Published: 15 March 2011
Suspensions of nanoparticles (i.e., particles with diameters < 100 nm) in liquids, termed nanofluids, show remarkable thermal and optical property changes from the base liquid at low particle loadings. Recent studies also indicate that selected nanofluids may improve the efficiency of direct absorption solar thermal collectors. To determine the effectiveness of nanofluids in solar applications, their ability to convert light energy to thermal energy must be known. That is, their absorption of the solar spectrum must be established. Accordingly, this study compares model predictions to spectroscopic measurements of extinction coefficients over wavelengths that are important for solar energy (0.25 to 2.5 μm). A simple addition of the base fluid and nanoparticle extinction coefficients is applied as an approximation of the effective nanofluid extinction coefficient. Comparisons with measured extinction coefficients reveal that the approximation works well with water-based nanofluids containing graphite nanoparticles but less well with metallic nanoparticles and/or oil-based fluids. For the materials used in this study, over 95% of incoming sunlight can be absorbed (in a nanofluid thickness ≥10 cm) with extremely low nanoparticle volume fractions - less than 1 × 10-5, or 10 parts per million. Thus, nanofluids could be used to absorb sunlight with a negligible amount of viscosity and/or density (read: pumping power) increase.
Nanofluids, or suspensions of nanoparticles in liquids, have been studied for at least 15 years and have shown promise to enhance a wide range of liquid properties [1–20]. In the last few years, the co-authors [21–23] and others [24, 25] have explored their potential towards developing a new type of direct absorption (or volumetric) solar thermal collector. The ideal volumetric thermal collector should: (1) efficiently absorb solar radiation (in the wavelength range - 0.25 < λ < 2.5 μm) and convert it to heat directly inside the working fluid, (2) minimize heat losses by convection and radiation (in the wavelength range - λ > 4 μm), and (3) keep system fouling/clogging and pumping costs to a minimum. The focus of this article is to explore condition (1) in detail for nanofluids.
where μeff and μf refer to the effective nanofluid viscosity and the base fluid viscosity, respectively. Also, Cμ can be found through a relation to several other fluid parameters - see . For many cases, though, Cμ = 10 is a reasonable approximation . If we plug in fv < 1 × 10-5, we can see that there is a negligible change in viscosity (i.e., μeff ≈ μf). If viscosity is unchanged, it is even less likely that density would change at these low volume fractions. Thus, pumping power (for a stable nanofluid) will not change. For these reasons, nanofluids compare favorably with black dye and micro/macroparticle laden liquids. They are also expected to show enhancement over conventional surface-based collectors [21–25].
On the other hand, recent research indicates that nanofluids must be very carefully chosen to match their application in order to see enhancement. This is especially true for the nanofluid optical properties in a solar collector. If the volume fraction of nanoparticles is very high, all the incoming light will be absorbed in a thin surface layer where the thermal energy is easily lost to the environment. On the other hand, if the volume fraction of nanoparticles is low, the nanofluid will not absorb all the incoming solar radiation. Therefore, the optical properties of the fluid must be controlled very precisely or a nanofluid could actually be detrimental in a solar collector. This article first describes some simple modeling (using bulk properties) approaches that we used to explore how a nanofluid absorb sunlight. Next, we will describe our experimentation methods towards this same end. These results will then be compared and discussed. Lastly, this study presents some nanofluid recipes with cost estimates for solar collector applications.
where m is the relative complex refractive index of the nanofluid and α is the size parameter, which depends on the particle diameter, D, and the incident wavelength, λ .
Effective medium approach to optical properties
where D is the particle diameter, N the number of scattering particles in the beam path, λ the wavelength of light, m the relative complex refractive index, and θ the scattering angle. Thus, a tripling of the diameter (from 30 to 90 nm) gives a 730-fold increase in the amount of scattering! Thus, if particles in a real nanofluid are larger than what is assumed above, scattering may cause deviations from the model.
Creating a stable nanofluid is a must for any real application and for measuring optical properties. Without careful preparation, nanoparticles will agglomerate and settle out of the base fluid in a very short time. Although there are many methods of nanofluid preparation, they can be roughly categorized into "one-step" and "two-step" processes. One-step processes synthesize the nanofluid to the desired volume fraction and particle size inside the base fluid. Thus, the final product is a specific nanofluid which is ready for use (possibly after dilution). The two-step method is accomplished by first synthesizing the dry nanoparticles to a preferred size and shape. In the second step, these particles are carefully mixed into the desired base fluid at the desired volume fraction, usually with some additives for stability.
Several researchers have had success fabricating and testing nanofluids using one-step preparation methods [33–35]. Based on these results, one-step methods may produce the best results for commercial applications if they can be scaled up and manufactured inexpensively. However, due to its straightforward nature and its controllability, we will only use and discuss the two-step method.
A variety of dry powders are available "off-the-shelf" [36–38]. These particles can be mixed into many different liquids at the preferred concentration. Depending on the stability and quality required, this process can take anywhere from a few minutes to several hours. For the test fluids of this article, the particles and up to 1% sodium dodecyl sulfate (a surfactant) were dispersed into the base fluid using a sonicator (a UP200 from Hielscher Ultrasonics GmbH, Teltow, Germany) for 15 to 30 min. From our experience, probe-type sonicators break particle agglomerates faster and much more thoroughly than bath-type sonicators. Since it is relatively quick, requires very little "high tech" equipment, and produces any number of nanofluids, this process is our method of choice. Unfortunately, surfactant-stabilized nanofluids are known to break down at elevated temperature . For longer-term stability in a solar application, one can re-sonicate continuously or attempt more exotic preparation methods, such as those given in [34, 40].
To measure the optical properties, we used a spectrophotometer. This is a device that sends a light beam of variable wavelength through a sample and then detects the transmitted beam. Spectrophotometers come in several configurations and are good for a variety of wavelengths. For our purposes, we need measurements over the solar spectrum, i.e., between 0.20 to 3 μm. As such, we mostly use a Jasco V-670 (Jasco Corp., Great Dunmow, Essex, UK) which can take transmission measurements in the range of 0.19 to 2.7 μm, although other spectrophotometers are used for comparison in our testing.
If our simplistic nanofluid model is accurate, σEXP should be directly comparable to the modeled quantity, σtotal, described in the previous section.
To determine the particle size in solution, dynamic light scattering (DLS) was done for selected materials - graphite (30 nm manufacturer-quoted average particle size (APS)) and silver (20 nm manufacturer APS). The equipment used to do these measurements was a Nicomp 380 DLS (Agilent Technologies, Inc., Santa Clara, CA, USA). Results gave volume-weighted average particle sizes to be 150 to 160 nm and 50 to 70 nm for graphite and silver, respectively. In both cases, the standard deviation was around half of the volume-weighted average. DLS testing also revealed that 24 h later the samples heavily clumped into 1 to 15 μm aggregates, showing that our preparation method for these fluids is only good for short-term stability. It should be noted that the volume-weighted average yields particle sizes that lie between number and intensity-weighted averages.
Results and discussion
The concentrations shown in Figure 5 represent a very wide range which could accommodate almost any solar receiver geometry. Overall, there is very good agreement between model and experimental results. Depending on volume fraction, the nanoparticles appear to be the absorbing material for shorter wavelengths (up to approximately 1 μm for 1 × 10-5 vol.% and up to approximately 2 μm for 0.1 vol.%), whereas at longer wavelengths, water becomes dominant and the curves converge. These results indicate that our simplistic approach (i.e., Equations 2 to 9) agrees well with experimental data.
Since the base fluid is a good absorber at longer wavelengths, it will also be a good emitter at those same wavelengths. That is, most nanofluids are also expected to have radiation losses nearing those of a blackbody at longer wavelengths (> 4 μm) according to Plank's radiation law. There are two possible solutions to this problem for a solar collector: (1) find a base fluid which has low emission for long wavelengths and (2) install a cover/glazing over the collector which will trap long-wavelength emitted radiation from leaving the system. The second solution is most likely to be adopted since (as mentioned above) there are many commercial materials which could be used to minimize losses and are still essentially transparent to the solar spectrum [26, 27].
Figure 6 also shows less agreement between the model results and the experimental results for metals than is seen for graphite. Most noticeably in silver, we expected to see a large peak in the extinction coefficient. This peak, referred to as the plasmon peak, is a built-in natural frequency where electrons will absorb and oscillate strongly in a metal. It is usually found in the range of 200 to 500 nm. However, our experimental results for metal-based nanofluid were rather constant and did not show a large, pronounced plasmon peak as expected. In general, our model for metal nanofluids appears to over-predict from very short wavelengths until around 600 to 700 nm where it then begins to under-predict the extinction coefficient.
The accuracy of this system is at least ± 0.3%T. Thus, if we get a result of 90% transmission, it could actually be 89.7% or 90.3% transmission. However, the poor match in results in Figures 6 and 7 cannot be explained by this error. One possible reason for the discrepancy, however, is that particle agglomerates are in the measurement beam path and absorb or scatter an anomalously large amount of light. That is, the real particle shape or size might deviate from the nominal manufacturer-stated nanoparticle specifications. Furthermore, the model assumes a monatomic particle distribution. That is, all the particles of a given sample are assumed to be the same size - thus, the average particle diameter quoted by the manufacturer. Another possible explanation for the poor agreement is that an oxide layer or other chemical deviation may occur in the metal nanoparticles giving different properties than that assumed in the bulk metal.
As mentioned above, scattering can also come into play, especially important at short wavelengths. Taking the results of Figure 8 and a nominal particle size of 100 nm, up to 5% of the incident light can be scattered in a solar nanofluid. In a 10-cm fluid depth, this translates to an average extinction coefficient of 0.05 cm-1. Overall, these results show that a measurable amount of light can be scattered if large particles or particle agglomerates are present. If the particle size is < 50 nm, however, scattering is negligible - so care must be taken to make sure that the particles in a nanofluid stay "nano."
Conclusions and future work
This article has shown measurement and modeling techniques for determining the optical properties of nanofluids. These two methods of determining optical properties are in very good agreement for graphite nanofluids. They also correspond well in the case of aluminum. However, experimental results did not match well with the model predictions for the other metals tested, particularly missing the large predicted plasmon peaks (e.g., silver). Particle size was discredited as the root of poor model predictions for metals. Scattering is expected to be negligible if care is taken to keep particles in solution near their manufacturer-listed diameters - so this is also unlikely to lead to significant errors. One possible explanation is purity of the materials. For instance, oxidization or other impurities on the particle surface might be responsible for the poor agreement with the model.
Solar thermal nanofluid comparison table
1M NaOH, vol.% (achieve pH 9 to 10)
Sonication time, min
Collector depth, cm
Approximate cost, $/L
Further work will be necessary to obtain better models for nanofluids containing metallic nanoparticles other than aluminum. Also, a more in-depth study will be required to obtain optical properties at elevated temperatures. Since liquid-based solar thermal collectors can operate anywhere from 50°C to 500°C, it is very important to characterize these properties at those temperatures. We predict that nanofluids would be most cost-effectively placed into solar systems with a relatively small receiver area (such as a power tower or dish receiver), but more work must be done to determine the most advantageous use of solar nanofluids.
D: Mean particle diameter (nm); fv: Volume fraction (%); I: Irradiance, W m-2; k: Complex component of the refractive index; L: Path length, mm; m: Relative complex refractive index (particles to fluid); N: Number of scatterers; n: Real component of the refractive index; Q: Optical efficiency factor; R: Reflectivity; T: Transmissivity.
║: Parallel component; ┴: Perpendicular component; abs: Absorption; e: Effective; ext: Extinction; EXP: Experimental result; F: Fluid; MOD: Modeling result; scat: Scattering.
α: Particle size parameter; ε': Real component of the dielectric constant, F/m or (kg mm mV-2 s-2); ε": Complex component of the dielectric constant, F/m or (kg mm mV-2 s-2); θ: Scattering angle, radians; λ: Wavelength, μm; π: The constant, pi; ρ: Density, kg/m3 or #/m3; σ: Extinction coefficient, 1/cm.
The authors gratefully acknowledge the support of the National Science Foundation through award CBET-0932720.
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Enjoy some of the extensive magazine, newspaper and web-based coverage of our work through the years.
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By. GENEVIEVE BOOKWALTER
SANTA CRUZ -- New rules proposed to protect endangered leatherback turtles off the West Coast could have far-reaching effects on Monterey Bay clean energy, desalination and other projects as federal officials seek a balance between increased human demands on the sea and resources that the rare creatures need to survive.
The proposed rules released Tuesday by the National Oceanic and Atmospheric Administration set aside 70,000 watery acres as critical habitat for leatherback sea turtles. The boundary in California stretches from Mendocino County's Point Arena to Point Vicente in Los Angeles County. Farther north, the boundary reaches from Cape Flattery in Washington to the Umpqua River in Oregon.
The new rules do not govern fishermen, who already must follow regulations issued by NOAA's National Marine Fisheries Service to make sure turtles are not accidentally caught in gill nets or through other fishing techniques.
Specific details governing various projects were not included in Tuesday's proposed rules. Instead, by designating the areas as critical habitat, those wanting to drill for oil or natural gas, build desalination plants, harvest wave energy, build windmills or operate fish farms within must first consider how those projects might harm sea turtles and find ways to offset them, according to the proposal.
Scott Benson, a NOAA research fishery biologist in Moss Landing who helped draft the new rules, compared them to city zoning regulations that prevent factory developers from building next to busy neighborhoods.
"You can't put a factory anywhere. You have to put it in a particular place that's zoned for a factory," Benson said. Likewise, future windmills and other projects should not be built near turtle foraging grounds, he said.
Leatherback sea turtles travel to Monterey Bay and the U.S. West Coast each year from their nesting beaches in the South Pacific. The turtles arrive in late summer and early fall to feast on an abundance of jellyfish, their favorite food. They can grow up to 9 feet long with a front-flipper-span of 8 feet across. They have been listed as endangered since 1970.
Benson predicted more, similar rules from NOAA in the near future to protect other endangered species as wind farms, desalination plants and other ocean projects become more popular.
Sea turtle researcher Wallace J. Nichols of Davenport, who works with the California Academy of Sciences in San Francisco, said the additional rules are necessary as humans increasingly turn to the sea to meet their water and power needs.
"New industries emerging as a result of the growing scarcity of water and oil will bring new kinds of impacts," Nichols said. "Designating these waters as critical habitat is a necessary step to stem sea turtle declines and begin their recovery."
Santa Cruz Water Department Director Bill Kocher said his department already is considering myriad regulations as the city moves forward with its long-planned desalination plant. He doesn't expect new turtle protections -- whose effects on the proposed plant have not been worked out -- to derail the project.
"We haven't spent a lot of time looking at leatherbacks, but I don't have the sense that it's going to add a particular level of complexity," Kocher said. While he plans to read and comment on the new rules, "we don't make it our point to take opposition to things that protect threatened and endangered species," he said.
The proposed protections follow a lawsuit filed by environmental groups Oceana, Center for Biological Diversity and Turtle Island Restoration Network last year accusing the government agency of taking too long to finish them. They originally were due in 2008. Public comment will be taken through March 8, after which NOAA officials have a year to prepare their final report.
Andrea Treece, a senior attorney with the Center for Biological Diversity in San Francisco, said her group welcomes the proposed regulations but would like to see NOAA further include more ocean acreage and address the effects of commercial fishing gear, which Tuesday's rules did not do.
"I think there's a good amount of support for this," Treece said, "protecting this habitat and protecting this species."
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Researchers at the University of Miami and the University of Ulster have created nanoparticles that can transport interacting molecules into living cells.
With the continuing need for very small devices in therapeutic applications, there is a growing demand for the development of nanoparticles that can transport and deliver drugs to target cells in the human body.
The sequential transport of donors and acceptors across cell membranes with independent and dynamic nanocarriers enables energy transfer exclusively in the intracellular space with concomitant fluorescence activation.
Credit: Francisco Raymo, professor of Chemistry and director of the laboratory for molecular photonics, at the University of Miami College of Arts and Sciences
Recently, researchers created nanoparticles that under the right conditions, self-assemble – trapping complementary guest molecules within their structure. Like tiny submarines, these versatile nanocarriers can navigate in the watery environment surrounding cells and transport their guest molecules through the membrane of living cells to sequentially deliver their cargo.
Although the transport of molecules inside cells with nanoparticles has been previously achieved using various methods, researchers have developed nanoparticles capable of delivering and exchanging complementary molecules. For practical applications, these nanocarriers are highly desirable, explains Francisco Raymo, professor of chemistry in the University of Miami College of Arts and Sciences and lead investigator of this project.
"The ability to deliver distinct species inside cells independently and force them to interact, exclusively in the intracellular environment, can evolve into a valuable strategy to activate drugs inside cells," Raymo says.
The new nanocarriers are15 nanometers in diameter. They are supramolecular constructs made up of building blocks called amphiphilic polymers. These nanocarriers hold the guest molecules within the confines of their water-insoluble interior and use their water-soluble exterior to travel through an aqueous environment. As a result, these nanovehicles are ideal for transferring molecules that would otherwise be insoluble in water, across a liquid environment.
"Once inside a living cell, the particles mix and exchange their cargo. This interaction enables the energy transfer between the internalized molecules," says Raymo, director of the UM laboratory for molecular photonics. "If the complementary energy donors and acceptors are loaded separately and sequentially, the transfer of energy between them occurs exclusively within the intracellular space," he says. "As the energy transfer takes place, the acceptors emit a fluorescent signal that can be observed with a microscope."
Essential to this mechanism are the noncovalent bonds that loosely hold the supramolecular constructs together. These weak bonds exist between molecules with complementary shapes and electronic properties. They are responsible for the ability of the supramolecules to assemble spontaneously in liquid environments. Under the right conditions, the reversibility of these weak noncovalent contacts allows the supramolecular constructs to exchange their components as well as their cargo.
The experiments were conducted with cell cultures. It is not yet known if the nanoparticles can actually travel through the bloodstream.
"That would be the dream, but we have no evidence that they can actually do so," Raymo says. "However, this is the direction we are heading."
The next phase of this investigation involves demonstrating that this method can be used to do chemical reactions inside cells, instead of energy transfers.
"The size of these nanoparticles, their dynamic character and the fact that the reactions take place under normal biological conditions (at ambient temperature and neutral environment) makes these nanoparticles an ideal vehicle for the controlled activation of therapeutics, directly inside the cells," Raymo says.
The current study is titled "Intracellular guest exchange between dynamic supramolecular hosts." It's published in the Journal of the American Chemical Society. Other authors are John F. Callan, co-corresponding author of the study, from the School of Pharmacy and Pharmaceutical Sciences at the University of Ulster; Subramani Swaminathan and Janet Cusido from the UM's Laboratory for Molecular Photonics, Department of Chemistry in the College of Arts and Sciences; and Colin Fowley and Bridgeen McCuaghan, School of Pharmacy and Pharmaceutical Sciences at the University of Ulster.
The University of Miami's mission is to educate and nurture students, to create knowledge, and to provide service to our community and beyond. Committed to excellence and proud of our diversity of our University family, we strive to develop future leaders of our nation and the world.
Annette Gallagher | Eurek Alert!
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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.
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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.
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17.07.2018 | Power and Electrical Engineering | <urn:uuid:c36d42eb-0dc8-4d66-b7fe-5e666a00e0c4> | 3.40625 | 1,583 | Content Listing | Science & Tech. | 23.09704 | 95,548,316 |
Scientists have developed electrodes that could clean pollutants in wastewater. These electrodes are coated with a conductive polymer referred to as PEDOT. This discovery could make the cleaning wastewater more efficient and inexpensive too.
The research was published in the Journal of Power Sources. It was led by scientists and bioelectrochemical engineers from Cornell University, according to Science Daily.
So, how does it work? Once the nanofiber electrodes were coated with PEDOT, an electrically active layer of bacteria known as Geobacter sulfurreducen, they grow to generate electricity and transport electrons to the novel electrode. Then, the nanofibers produce a surface for this bacteria and absorb the contaminants from the wastewater and produce electricity, too.
The electrode is an electrical conductor that could be in contact with a nonmetallic part of a circuit such as an electrolyte, air, semiconductor or a vacuum. In the electrochemical cell, the electrode could either be an anode or cathode. The anode is indicated by a minus symbol. Meanwhile, the cathode is indicated by a plus symbol. The electrode could either be anode or cathode depending on the direction of the current in the cell.
Juan Guzman, a co-lead author and a doctoral candidate in the field of biological and environmental engineering, said that electrodes are expensive to create now. This material could bring the prize of electrodes way down and could make it easier to clean up polluted water. The nanofiber electrode looks like a kitchen scrubber as seen in a microscope.
Meanwhile, Meryem Pehlivaner, a doctoral student at Northeastern University, and Margaret Frey, the senior author and a professor of fiber science and an associate dean of the College of Human Ecology, made the electrode. Pehlivaner manufactured the carbon nanofibers through the processes of carbonization and electrospinning. Then, after electrospinning for a few hours, the thick nanofiber sheet was developed.
This customized carbon nanofiber electrode was then used for its high absorbency, surface area and biocompatibility with the bacteria. It was also enhanced by applying the PEDOT to make the material more efficient. | <urn:uuid:157a6daf-e131-4712-9682-a74840326fce> | 3.8125 | 450 | News Article | Science & Tech. | 21.201667 | 95,548,385 |
Painful stings and lethal allergies can evoke fear of bees. However, bee scholar Marla Spivak candidly explains that humans have much more to fear regarding these amazing social insects: Their numbers are depleting, and if their struggle for survival continues, large sectors of the global food chain and of the agricultural industry will face extinction. getAbstract recommends Spivak’s mesmerizing report and solutions to those employed in agriculture, civic leaders, environmental activists and anyone concerned with securing the food supply for future generations.
In this summary, you will learn
- Why bees are critical to the food chain,
- Which human behaviors have disrupted the bee ecosystem
- How simple steps can improve the odds of bee survival.
About the Speaker
Marla Spivak is a professor of entomology at the University of Minnesota.
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The Guardian, 2017 | <urn:uuid:ffc4d421-98bb-45ac-bcaf-a1c8268ce3ba> | 2.796875 | 218 | Truncated | Science & Tech. | 27.188441 | 95,548,413 |
Kinematic histories of fold-thrust belts are typically based on careful examinations of high-grade metamorphic rocks within a salient. We provide a novel method of understanding fold-thrust belts by examining salient-recess junctions. We analyze the oft-ignored upper crustal rocks using a combined approach of detailed fault analysis with experimental sandbox modeling.
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Ismat, Z., Toeneboehn, K. Kinematic History of a Salient-recess Junction Explored through a Combined Approach of Field Data and Analog Sandbox Modeling. J. Vis. Exp. (114), e54318, doi:10.3791/54318 (2016).
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Within fold-thrust belts, the junctions between salients and recesses may hold critical clues to the overall kinematic history. The deformation history within these junctions is best preserved in areas where thrust sheets extend from a salient through an adjacent recess. We examine one such junction within the Sevier fold-thrust belt (western United States) along the Leamington transverse zone, northern Utah. Deformation within this junction took place by faulting and cataclastic flow. Here, we describe a protocol that examines these fault patterns to better understand the kinematic history of the field area. Fault data is supplemented by analog sandbox experiments. This study suggests that, in detail, deformation within the overlying thrust sheet may not directly reflect the underlying basement structure. We demonstrate that this combined field-experimental approach is easy, accessible, and may provide more details to the deformation preserved in the crust than other more expensive methods, such as computer modeling. In addition, the sandbox model may help to explain why and how these details formed. This method can be applied throughout fold-thrust belts, where upper-crustal rocks are well preserved. In addition, it can be modified to study any part of the upper crust that has been deformed via elastico-frictional mechanisms. Finally, this combined approach may provide more details as to how fold-thrust belts maintain critical-taper and serve as potential targets for natural resource exploration.
Fold-thrust belts are composed of salients (or segments), where the thrust sheets in adjoining salients are decoupled by recesses or transverse zones1,2,3. The transition from salient to recess may be markedly complex, involving a multifaceted suite of structures, and may hold critical clues to fold-thrust belt development. In this paper, we carefully examine a salient-recess junction, using a combination of multiscale field data and a sandbox model, in order to better understand how deformation can be accommodated within fold-thrust belts.
The junction of the Central Utah segment and the Leamington transverse zone is an ideal natural-laboratory for studying salient-recess junctions for several reasons (Figure 1). First, the rocks exposed within the segment continue, uninterrupted, into the transverse zone4. So, deformation patterns can be tracked continuously, and compared across the junction. Second, the rocks are essentially monomineralic, so variation in fault patterns are not a result of heterogeneities within units, but instead reflect the overall folding and thrusting within the study area4. Third, elastico-frictional mechanisms, such as cataclastic flow, assisted deformation throughout the field area, allowing for direct comparisons of mesoscale fault patterns4. Finally, the overall transport direction remained continuous along the length of the segment and transverse zone; therefore, variations in shortening direction did not influence the preserved deformation patterns4. All of these factors minimize the number of variables that may have affected the deformation along the segment and transverse zone. As a result, we surmise that the preserved structures formed primarily because of a change in the underlying basement geometry5.
Figure 1. Example of index map. The Sevier fold-thrust belt of western USA, showing major salients, segments, recesses and transverse zones. Figure 2 indicated by boxed area (modified from Ismat and Toeneboehn7). Please click here to view a larger version of this figure.
Folding and thrusting within the Central Utah segment and Leamington transverse zone, took place at depths < 15 km, i.e., within the elastico-frictional regime, where deformation occurred primarily by outcrop-scale (< 1 m) faults and cataclastic flow4,6. Because transport and folding of the thrust sheet took place primarily by elastico-frictional mechanisms, we predict that a detailed fault analysis can provide further insight into the kinematic history of the Leamington transverse zone and the underlying basement geometry. In order to test this hypothesis, we have collected and analyzed fault patterns preserved in the rocks within the northern portion of the Central Utah segment and throughout the Leamington transverse zone (Figure 2).
Figure 2. Example of macroscale topographic map. Shaded-relief topographic map of boxed area in Figure 1. The 4 Regions are separated by solid white lines. Bedding contacts between the Proterozoic Caddy Canyon quartzite (PCc), Proterozoic Mutual quartzite (PCm) and Cambrian Tintic quartzite (Ct) are shown. Dashed lines show the trend of the mountains within this area. Site locations are shown with numbered black squares. First-order lineations are shown with solid gray lines (modified from Ismat and Toeneboehn7). Please click here to view a larger version of this figure.
Sandbox experiments were carried out to compare against, and supplement, the fault data. A push-block sandbox model, with frontal and oblique ramps, was used to assist our analyses of the structures preserved in, and around, the Leamington transverse zone (Figure 3) 7. The objectives of this approach are four-fold: 1) determine if the mesoscale fault patterns are consistent, 2) determine if the sandbox model supports and explains the field data, 3) determine if the sandbox model provides more details on structures that are not observed in the field, and 4) evaluate whether this combined field-experimental method is useful and easy to replicate.
Figure 3. Example of push-block model. Photograph of empty sandbox model. The southern frontal ramp (SFR), oblique ramp (OR), northern frontal ramp (NFR), and the four Regions (1-4) are labeled (modified from Ismat and Toeneboehn7). Please click here to view a larger version of this figure.
1. Collection of Macroscale Field Data
- Before conducting field work, use aerial photographs/topographic maps to identify the overall trend of the mountains (defined by the modern-day ridge crest), transverse zones, faults and other lineations at the macroscale (Figure 2).
- Use similar scale topographic maps and aerial photographs, so that patterns can be directly compared. Use 1:24,000 scale maps and photographs.
- Label and highlight macroscale features on the maps (aerial and/or topographic) to be used in the field. On aerial photographs, use sharp changes in foliage to identify macroscale features, because the foliage patterns reflect the underlying bedrock. On topographic maps, use sharp changes in topography, such as steep cliffs, long narrow valleys and rapid changes in drainage patterns to identify macroscale features.
- Corroborate these map patterns, with macroscale features found in nature, while in the field. Ensure that the field maps are adjusted accordingly.
- Subdivide the field area along macroscale transverse zones.
2. Collection of Mesoscale Field Data
- Conduct field analysis within each transverse zone bound area.
- Determine the scale of homogeneity of the mesoscale faults throughout the field area. Do this by measuring all faults larger than 3 cm along a transect perpendicular and parallel to the overall macroscale structure. The point at which fault patterns repeat itself along the transect defines the scale of homogeneity.
Note: 3 cm is chosen as a minimum cut-off because faults smaller than 3 cm may be difficult to measure.
- Choose representative sites throughout the field area using the defined scale of homogeneity.
- Ensure that each site contains ~3 mutually perpendicular rock exposures within the scale of homogeneity, in order to quantify the three-dimensional geometry of the fault work.
- Ensure that new sites are chosen where the fault patterns markedly change (Figure 2).
- Choose sites far (~one unit of homogeneity) from major bedding contacts, in order to avoid local shortening and elongation directions that may have overprinted faults produced from the overall shortening direction.
- Use a grid to keep track of all the faults during data collection4.
- Ensure that the size of the grid is at the scale of homogeneity of the mesoscale faults. For example, if the faults are homogeneous at the cubic meter scale, use a meter square grid.
- Construct the grid as a collapsible wooden square — this allows for easier transport in the field.
- Use 4 equal pieces of 1 in wide strips of wood. Any type of hard wood is recommended because it is the most durable for field work.
- Drill 1/4" holes close to the ends (~ ½" from the ends) of the wood strips. Assemble with four 2 1/4" long, 3/16" size screws at each corner. Use steel wing nuts for easiest collapsibility.
- Divide the grid equally with string — this helps to track the various faults at each site. Drill holes, equally spaced, along the grids' perimeter, thread and tie string through the holes. For example, for a meter square grid, divide the grid into 10 cm squares with strings connected to the opposite ends of the grid (Figure 4).
Figure 4. Example of a mesoscale outcrop. Bedding is highlighted with white dashed lines. Specific fault sets discussed in paper are highlighted with thin, solid white lines. m2 grid is shown (modified from Ismat and Toeneboehn7). Please click here to view a larger version of this figure.
- Make detailed sketches of the fault sets within each grid.
- Based on the grid sketches and cross-cutting relationships of the faults, determine the youngest fault sets at each site4.
- Do this by identifying offset fault patterns at each site. The youngest faults overprint and offset the older faults.
- At each study site, record the orientation, spacing, length, thickness, and morphological characteristics (e.g., healed, vein filled, open, breccia filled) for each of the youngest faults within each grid.
- Divide the sites amongst the lithologic units (see Figure 2).
3. Collection of Microscale Data
- Collect oriented rock samples at each site for thin-section analysis.
- Ensure that the rock sample is large enough to cut three mutually perpendicular standard size (26 mm x 46 mm) thin-section chips (i.e., slightly larger than an adult fist).
- Cut thin-section chips (using a standard rock-saw) comparable to the grid orientations from each site, so that the microscale and mesoscale patterns can be directly compared.
- Prepare standard thickness (0.03 mm) thin-sections8.
- Analyze the thin-sections using a standard optical microscope with an attached camera, for taking photomicrographs.
- For each thin-section, record morphological characteristics, such as the amount of iron-oxide, and variation and average grain size by using stereological methods, i.e., Spektor Chord analysis (Table 1)9.
- Do this by measuring the width and/or number of chosen morphological characteristics along 4-6 randomly oriented transects through each thin-section4,9. From all of the transects, calculate the average (Table 1).
|Unit||Bed thickness (m)||Bedding fabric||Grain size (m)||X/Z Fry strain (Average Rf)||X/Y Fry strain (Average Rf)||Amount of overgrowth||Amount of iron oxide||Amount of impurities||Other characteristics|
|Ct||1,000||Prominent, thick and thin bedded||Ave: 1.59 x 10-4
(Range: 3.6 x 10-6 to 3.31 x 10-4)
|1.15||1.12||moderate, semi-connected in small patches||moderate, semi-connected in small patches||moderate, semi-connected calcite in small patches||Ridge former, white to grayish-pink, weathers tan to reddish brown|
|PCm||570-750||Prominent, well-developed graded and cross-bedding||Ave: 1.48 x 10-4
(Range: 1.15 x 10-4 to 2 x 10-4)
|1.22||1.19||major and well-connected||moderate and well-connected||minor calcite and poorly connected||Massive outcrops, purplish red-brown, weathers purple-black|
Table 1. Example of microscale morphology. Description of the Proterozoic Mutual (PCm) and Eocambrian Tintic (Ct) quartzite units. X/Z Fry strain is measured in a vertical section parallel to the transport plane, while X/Y Fry strain is measured in a vertical section perpendicular to the transport plane (modified from Ismat and Toeneboehn7). Please click here to view/download this table in Microsoft Excel format.
- Measure strain using normalized Fry analysis10,11. Ensure that strain is measured from three mutually perpendicular thin-sections in order to determine three-dimensional strain at each site.
- Do this by taking a photomicrograph of each thin-section. Ensure that the photomicrographs contain at least 50 grains with solid grain boundaries, i.e., not sub-grain boundaries.
- Define the outlines of the grains in order to measure Fry strain. Define the outlines either manually, by tracing the outlines from a printed photomicrograph onto tracing paper, or digitally, by uploading the photomicrograph into an image analysis software program (e.g., Image Pro Plus) that automatically defines the grains' boundaries.
- Upload the grain boundary image into the normalized Fry Strain program12.
4. Plotting Mesoscale Fault Data
- Analyze the fault data on Equal-area nets. For example, use Stereonet (freeware from R.W. Allmendinger).
- Plot the fault sets' poles on Equal-area nets and then contour these poles using 1% area contours (Figure 5).
- Determine the most common fault sets from these pole concentrations. Plot these fault sets as great-circles (Figure 5).
Figure 5. Examples of Equal-area plots. Equal-area plots of fault sets from two sites — site 41 is from Region 2 and site 5 is from Region 1. Fault sets are plotted as contoured poles (1% area contours). Average fault sets are determined from pole-concentrations and plotted as great circles. Maximum shortening directions, determined from conjugate-conjugate fault sets, are plotted as black dots. Fault-pole contours are colored according to percentage contribution at each site. Pole concentrations that contribute to >20% are colored red, between 15-19% are colored orange, 10-14% are yellow, 5-9% are green and <5% are colored blue. Red fault-pole contours are labeled as LPS (layer-parallel shortening), LE (limb extension), and HE (hinge-extension) (modified from Ismat and Toeneboehn7). Please click here to view a larger version of this figure.
- Identify the conjugate fault sets, i.e., the great-circle pairs with dihedral angles that range from 40º to 75º (Figure 5)13.
- Define the acute bisector of the conjugate-conjugate fault sets — this locates the maximum shortening direction (Figure 5) 4,14,15.
- Further subdivide the equal-area net fault-pole concentrations, according to their percentage contribution for each site. Do this by color coding the pole concentrations, for easier visual analysis. For example, highlight pole concentrations that contribute to >20% of the overall poles for that site red. Color those that contribute between 15-19% orange, 10-14% yellow, 5-9% green and <5% blue (Figure 5, Table 2).
|Site||Bedding||Shortening||Highest fault-pole||Fault sets(s)|
|(dip, dip direction)||directions(s)||concentration(s)||(dip, dip direction)|
|(plunge, trend)||(plunge, trend)|
|41||83, 268||79, 115||22, 064||68, 244|
|60, 345||30, 265|
|73, 276||17, 096|
|5||63, 265||67, 130||08, 343||82, 263|
|36, 247||54, 067|
Table 2. Example of mesoscale fault data. Chart, showing just 2 of the 24 sites, documenting the following: bedding orientation, shortening direction(s), orientation of the highest fault pole concentration(s) and their corresponding fault set(s) (modified from Ismat and Toeneboehn7).
- Label the pole concentrations according to different fault types (e.g., hinge extension) (Figure 5).
- Label the different fault types on the mesoscale photos, for easier visual analysis (Figure 4).
- Graph the different fault types, for easier visual analysis (Figure 6). Do this by graphing the fault data along and across the overall macroscale structure.
Figure 6. Example graph showing distribution of fault populations. Graph showing the percentage and type of the maximum fault sets (highlighted in red in Figure 5) for each site. Just sites within the Ct quartzite are shown here (modified from Ismat and Toeneboehn7). Please click here to view a larger version of this figure.
5. Construction of the Push-block Sandbox Model
- Use ¾ inch MDF (medium-density fiberboard) to reduce potential surface heterogeneities arising from wood grain, coarsely planed surfaces, or other defects from lumber (Figure 3).
- Apply a basic finishing lacquer to seal the surfaces of the MDF board and prevent epoxy (described below) from permeating the model's surfaces (Figure 3).
- Scale and orient the sandbox model to the field area. For example, in this study, model the length of the box to represent the EW trend line, and model the width of the box to represent the NS trend line. Scale the sandbox model where 4 cm is equal to 1 km (Figure 3).
- Construct the box larger than the field study area in order to avoid potential boundary conditions and/or edge effects from the model.
- Do not construct a backstop, in order to allow sand to pass without an unrealistic boundary (Figure 3).
- Build a push-block equivalent to the width of the sandbox. This will prevent sand from passing through the sides of the push-block.
- Use ¾ inch MDF for the push block.
- Attach the push-block to a crank driven threaded metal bar (Figure 7).
- Use a 4-6 inch diameter circular crank with a handle — a circular crank puts less strain on the attendant's wrist and hands.
- Use a zinc-plated threaded bar (preferably acme threaded) that is at least ¾ inch in diameter. If the bar is too thin, it may not be able to withstand the weight of the sand.
- Ensure that the length of the threaded bar extends from the beginning of the sandbox to the end of the ramps.
Figure 7. Example sandbox model diagram. Diagrams for the sandbox model, illustrated as plan and cross-sectional views. The southern frontal ramp (SFR), oblique ramp (OR) and northern frontal ramp (NFR) are labeled. Thin arrows drawn over the ramps illustrate potential direction of sand movement. See Figure 3 for a photograph of an empty sandbox model (modified from Ismat and Toeneboehn7). Please click here to view a larger version of this figure.
- Drill an elongated hole, with a vertical long axis, in the center of the frontstop. This elongated shape will allow the push-block (attached to the threaded bar) to move up and over the ramps, if needed (Figure 8).
- Ensure that the length of the elongated hole is equal to the height of the tallest ramp.
- Secure the elongated hole with a metal frame. Attach the metal frame to the frontstop with nuts and bolts (Figure 8).
- Thread the rod through a matching pitch and diameter nut mounted to the frontstop (Figure 8).
Figure 8. Example threaded bar connection. Close-up view of the threaded bar and matching nut mounted to the frontstop. Please click here to view a larger version of this figure.
- Construct an oblique ramp, bound on both sides by frontal ramps. Construct the ramps out of pine with glued rabbet joints on the top surfaces and countersunk fasteners along the base.
- Cut the ramps at comparable orientations to what is predicted in the field.
- Expand the distance between the various ramps, as compared to what is observed in the field, so that the structures that form in the sand are more visible.
- Sand the surfaces with a fine grit sanding paper to remove surface heterogeneities and apply a polyurethane finish to protect the soft wood.
- Cover the ramps and the base of the sandbox with painters tape to protect the wood from epoxy between trials. Ensure that the tape is smooth and free from ridges or flaps.
6. Running the Push-block Sandbox Model
- Use typical play-sand. This type of sand is relatively homogeneous, with an average grain size of 0.5 mm.
- Dye and dry half of the sand.
- Fill a 5-gallon bucket a quarter full with play-sand and add black food coloring while mixing until a uniform dark green color is attained. Use as much dye as is needed to make the color of the dyed sand clearly distinctive from the undyed sand.
- Allow sand to dry at room temperature, which may take several days, or in an oven (up to 500 ºC), which may only take a few hours. Do not place hot sand in the sandbox. Ensure that the sand has cooled to room temperature before use.
- Lay the sand in alternating layers of colored and uncolored (tan) sand. Test various thicknesses of sandpacks. In this set-up, the clearest and most reproducible results were produced with a sandpack 3.5 cm thick, with alternating colored and tan layers 0.6 cm thick (Figure 7).
- Gently press a plastic mesh, composed of 0.5 in2 (1.3 cm2) squares onto the top of the undeformed sand to produce a grid indentation (Figure 9).
Figure 9. Example of undeformed sand in sandbox model. Partial plan-view of undeformed sand in sandbox model. Note grid indentation and square cross-pins. The southern frontal ramp (SFR), oblique ramp (OR), northern frontal ramp (NFR), and the four Regions (1-4) are labeled (modified from Ismat and Toeneboehn7). Please click here to view a larger version of this figure.
- Insert square cross pins 2 inches (~5 cm) apart throughout the undeformed sand (Figure 9).
- Push the sand with the crank driven push-block. In this set-up, move the sand 60 cm, i.e., 60 cm of shortening (Figure 10).
- Move the push-block slow enough so that changes in the sand can be carefully documented. The speed at which the push-block is moved (i.e., strain rate) does not affect the results.
- Track the deformation by observing the shape changes of the squares (Figure 10).
- Track the amount of transport and vertical rotation by observing the motion of the pins (Figure 10).
- Document all of these changes with a camera mounted near the sandbox, so that the entire sandbox is within the picture field. Ensure to take still frame photographs as well as videos.
Figure 10. Example of deformed sand layers. Plan-view of the end-result deformation from the sandbox model. Select cross-pins labeled with blue dots showing dextral offset. Folded cross-pins highlighted with yellow lines. Thrust faults are highlighted with thin, black lines. The four Regions (1-4) are labeled (modified from Ismat and Toeneboehn7). Please click here to view a larger version of this figure.
- Experiment with varying amounts of sand and total shortening.
- Repeat until satisfied, i.e., until the structures formed in the sandbox mimic those preserved in nature, under comparable shortening amounts.
7. Collecting Samples from the Sandbox
- Remove all cross-pins from the sand once the sandbox results mimic those preserved in nature.
- Collect samples from the sandbox by separating and epoxying portions of the deformed sand (Figure 11).
- Do this by constructing two pre-cut sheet-metal dividers to isolate portions of the deformed sand (Figure 9).
- Ensure that the bottom edge of the divider is cut to match the angle of the ramp.
- To protect the dividers from epoxy between trials, cover the dividers with painters tape (Figure 11).
- Ensure that the dividers extend over and beyond the ramps. In this study, use rectangular dividers that measured 45 cm long and 9 cm wide (Figure 11).
- Ensure that the dividers are taller than the thickest portion of the deformed sandpack (Figure 11).
- Ensure that one end of the divider is closed, in order to control the flow of the epoxy. Do not close the other end of the divider, in order to minimize any potential disturbance to the sandpack (Figure 11).
Figure 11. Example of metal dividers. Plan-view, showing 2 metal dividers, one through a frontal ramp and one through the oblique ramp, in the deformed sand. The metal divider along the oblique ramp is filled with epoxy. Note tape measure for scale (Modified from Ismat and Toeneboehn7). Please click here to view a larger version of this figure.
- Steady the dividers with metal bars (Figure 11).
- Do this by fastening the dividers with ¼ inch x 4 inch machine screws through pre-drilled holes toward the top of the dividers. Sheath the screws with 3/8 inch diameter aluminum tubing between the divider's sides. In this study, use two metal bars for each divider (Figure 11).
- Place one divider on the oblique ramp, and the second on the frontal-oblique ramp junction (Figure 11).
- Pour warmed epoxy across the top of the sand portions isolated by the metal dividers (Figure 11).
- Continue to pour epoxy until it is no longer absorbed by the sand. This ensures that the sand is fully saturated.
- Pull the epoxied areas out of the metal dividers, once the epoxy is dry. Do this by pulling the dividers out with the metal bars.
- Using a rock saw, cut the epoxied areas perpendicular and parallel to the strike of the ramps.
- Highlight the bedding, folds and faults with a permanent marker on the epoxied samples (Figure 12).
Figure 12. Examples epoxied samples from sandbox model. Epoxied samples from the (a) northern frontal ramp and the (b) oblique ramp within the sandbox model. Shown samples are cut perpendicular to the trend of the ramps. Layers are highlighted with thin, white lines. Solid white lines mark reverse faults, dashed white lines mark strike slip faults (modified from Ismat and Toeneboehn7). Please click here to view a larger version of this figure.
- Compare the sandbox samples to the field data.
- Compare samples with cross-sections from the area. Be sure the samples and cross-sections have similar orientations.
Aerial photographs were used to subdivide the field area into four Regions (1-4), based on the trend of the modern mountain ridge crest (Figure 2). Multi-scale fault data is compared between these four Regions. Assuming that these trend changes reflect the underlying basement geometry, the oblique ramp is positioned within Regions 2 and 3, where the mountains trend oblique to the Sevier fold-thrust belt. Throughout the four Regions, we found that the mesoscale faults preserve a deformation fabric that is penetrative and homogeneous at the mesoscale (i.e., cubic meter of rock) and are representative of areas larger than the cubic meter sites (Figure 4) 4,16. In addition, microscale variations, shown in Table 1, are not reflected in the collective character of fault patterns. So, the mesoscale fault sets can be directly compared throughout all four Regions (Figure 5). In brief, we found that the mesoscale faults sets can be defined as conjugate-conjugate sets and rotate with bedding, which entail that the shortening directions do, too. This pattern suggests that the mesoscale faults formed early, and different combinations of fault sets are used to assist the fold shape. In more detail, we found that the fault patterns are unique within each of the four regions — Regions 2 and 3, and Regions 1 and 4, are similar to each other (Figure 6). This pattern supports the macroscale assumption that the oblique ramp underlies Regions 2 and 3, and suggests that our conjugate-conjugate fault analysis is reliable. Beyond that, however, this method of analysis is not any more illuminating. Because of this, we further analyzed the fault data by examining the Equal-area net fault-pole concentrations (Figure 5). This approach is used to track which of the youngest sets were most dominant during deformation. These patterns also suggest an oblique ramp underlying Regions 2 and 3, and unlike the conjugate-conjugate fault analysis, reveal a sharp break between these two Regions. Therefore, we interpret that this pole-concentration analysis is reliable and potentially elucidates subtle structures that may not be clear from the conjugate-conjugate fault method.
Similar to previous models, based on finite element modeling (FEM) we have assumed that the oblique ramp is continuous17. The sharp break in bedding and fault patterns across the boundary between Regions 2 and 3 can be explained by differential motion over a continuous oblique ramp. Alternatively, the discontinuity in bedding and fault patterns across Regions 2 and 3 may reflect a break in the underlying basement. Here, we compare our field data to our sandbox model results in order to test these two hypotheses. We found that a break in the overlying thrust sheet formed even though there was no break in the basement (Figure 10). Interestingly, the location and orientation of the break is comparable to the position and orientation of the boundary between Regions 2 and 3 on the macroscale maps. Therefore, the break observed in the overlying thrust sheet may have simply formed via a complex interaction of an eastward moving thrust sheet over an oblique ramp. In other words, deformation preserved in thrust sheets may not directly mirror the underlying basement geometry. So, this sandbox experiment successfully replicates, and potentially explains, fault patterns preserved in the field.
The epoxied sandbox samples were analyzed from the sandbox model to observe the internal structure of the deformed sand, and compare these structures against field observations. Two representative samples were analyzed — a sample from the frontal and oblique ramps (Figure 12). In general, the reverse faults and folds preserved in the epoxied samples from the frontal ramp accommodate transport to east, and those from the oblique ramp accommodate transport to the southeast. The strike-slip faults in all the samples accommodate dextral motion. This kinematic record along the frontal and oblique ramps supports previous models17-19, as well as the mesoscale fault data. These hand samples are novel way to analyze internal structures that may not be accessible in the field.
The Central Utah segment of the Sevier fold-thrust belt, and its northern boundary, the Leamington transverse zone serves as an ideal natural laboratory for studying salient-recess junctions (Figure 1). Along this junction, the transport direction remains constant and the thrust sheets are uninterrupted across the junction, so the only variable is the underlying basement geometry5.
Here, we present a method to analyze this type of salient-recess junction by combining multi-scale fault data collected in the field with a push-block sandbox model, which replicates the large-scale geometry of the field area. The sandbox model experiment represents a longer time period of deformation than the mesoscale fault sets — we assume that the youngest fault sets accommodated the observed fold geometry. So, the sandbox model, in conjunction with the faults sets, can be used to track thrust sheet deformation and determine details of the underlying basement geometry.
In order for this combined approach to be successful, the following critical steps need to be taken in the field and sandbox experiment. For the field portion, it is critical to determine the scale of fault homogeneity — fault sets that are not preserved at equivalent scales cannot be directly compared. In addition, a large population of faults (≥ 30 fault sets) need to be measured in order ensure statistically reliable data sets9. Moreover, faults should be measured away from heterogeneities, such as bedding contacts, in order to avoid local strain variations. Even microscale variations, such as impurities, a range in grain size and large amount of strain (Fry > 1.8) may influence mesoscale fracture development by creating foliation planes and other heterogeneities. For the experimental portion, the sandbox model must mimic the field geometry as closely as possible. It is recommended that the box be constructed at a larger scope than the field area, in order to avoid edge-effect complications. The macroscale Regions were also enlarged, for the same reason. It is important that the grain size of the sand mimics Coulomb behavior20 — an average grain size of ~0.5 mm is recommended21. Finally, once the experiment is being run, it is critical that the large scale faults and folds form in the same orientations and order (e.g., forward breaking, backward breaking, etc.) as observed in the field. Otherwise, the structures formed in the model cannot be compared to the field data, even if they look similar.
The results from this study are comparable to, and support, previous work conducted in this area based on FEM17,22, and provides more details to the kinematic history. This suggests that detailed fault data, measured in areas that have deformed by elastico-frictional mechanisms, can be used to develop more detailed kinematic models than some computer models. Although fault data collection and analyses is laborious and time consuming, this method may be more accessible than computer and analog modeling, and is less expensive. Fractures and faults are often overlooked23 — many geologists view upper crustal deformation as minor and void of patterns. However, a large portion of the crust — the upper ~15 km — deforms by faulting and other elastico-frictional mechanisms. This work suggests that a significant amount of geologic history is stored in the upper crust and is readily available for analysis.
We demonstrate that even in the simplest cases, such as examined here, the structures preserved in the upper crust do not necessarily mimic the underlying basement geometry. Detailed fault analyses can reveal subtleties that may not be revealed with map patterns, standard conjugate fault studies and/or computer models, such as FEM. Using a sandbox model can help explain why some of these subtle patterns exist. This method presented here is simple, reliable and easy to replicate. It can potentially change how many geologists perceive the role of faults and cataclastic flow, and what they can tell us. This method can be used to re-examine, and uncover more kinematic details, of underexplored field areas, and can be easily modified to accommodate geologic settings other than fold-thrust belts. This approach has far reaching implications in terms of tracking fracture controlled fluid flow in the upper crust as well as how fold-thrust belts maintain critical taper at salient-recess junctions.
The main weakness of this approach is that sandbox modeling may not be able to replicate complex geologic histories. For example, in cases where there are variable shortening directions, the timing and direction of events should be carefully tracked in the field and then replicated with different push-blocks in the sandbox model. However, the sand will likely not preserve these various directions of shortening because the sand will flow and bedding layers will not be maintained. This problem may be resolved by adding oil or petroleum jelly to the sand, to make the sand more cohesive. But, then the sand will not behave as a Coulomb material and thus, may not model deformation in the upper crust. Further work is required to unravel more complex natural systems, such as situations where the basement geometry not the only variable.
The authors have nothing to disclose.
We thank Erin Bradley and Liz Cole for their assistance in the field. Field work, thin-section preparation and material for the sandbox model was supported by Franklin & Marshall College's Committee on Grants.
|epoxy||Epoxy technology||Parts A and B: 301-2 2LB||Best if warmed to 80º - 125º. If warming is not possible, it will cure fine, it will just take 1 week, rather than 1 day.|
|play sand||Any||NA||best if homogenous grain size, ~0.5 mm|
|food coloring||Any||NA||best to use one color and a dark color|
|square cross oins||Any||NA|
- Marshak, S., Wilkerson, M. S., Hsui, H. T. Generation of curved fold-thrust belts: Insights from simple physical and analytical. modelsThrust Tectonics. KR, M. cC. lay Chapman and Hall. 83-92 (1992).
- Mitra, G. Evolution of salients in a fold-and-thrust belt: the effects of sedimentary basin geometry, strain distribution and critical taper. Evolution of Geological Structures in Micro- to Macro-scales. S, S. engupta Chapman and Hall. 59-90 (1997).
- Weil, A., Sussman, A. Classifying curved orogens based on timing relationships between structural development and vertical axis rotations. Orogenic curvature Geol. Soc. of Am. Special Paper. A, S. ussman, A, W. eil 383, 205-223 (2004).
- Ismat, Z., Mitra, G. Folding by cataclastic flow at shallow crustal levels in the Canyon Range, Sevier orogenic belt, west-Central Utah. J. of Struct. Geol. 23, (2-3), 355-378 (2001).
- Tull, J., Holm, C. Structural evolution of a major Appalachian salient-recess junction: Consequences of oblique collisional convergence across a continental margin transform fault. Geol. Soc. of Am. Bull. 117, (3), 482-499 (2005).
- Ismat, Z. Block supported cataclastic flow within the upper crust. J. of Struct. Geol. 56, 118-128 (2013).
- Ismat, Z., Toeneboehn, K. Deformation along a salient-transverse zone junction: An example from the Leamington transverse zone,Utah, Sevier fold-thrust belt (USA). J. of Struct. Geol. 75, 60-79 (2015).
- Reed, F. S., Mergner, J. L. Preparation of Rock Thin Sections. Amer. Mineral. 38, 1184-1203 (1953).
- Underwood, E. E. Quantitative Stereology. Addison-Wesley Publishing Company. (1970).
- Fry, N. Random point distribution and strain measurement in rock. Tectonophys. 60, (1), 89-105 (1979).
- McNaught, M. A. Estimating uncertainty in normalized Fry plots using a bootstrap approach. J. of Struct. Geol. 24, (2), 311-322 (2002).
- De Paor, D. G. An Interactive Program for Doing Fry Strain Analysis on the Macintosh Microcomputer. J. of Geol. Ed. 37, (3), 171-180 (1989).
- Ismat, Z. Folding kinematics expressed in fracture patterns: An example from the Anti-Atlas fold-belt, Morocco. J. of Struct. Geol. 30, (11), 1396-1404 (2008).
- Reches, Z. Faulting of rocks in three-dimensional strain fields: II. Theoretical analysis. Tectonophys. 95, (1-2), 133-156 (1983).
- Reches, Z., Dieterich, J. H. Faulting of rocks in three dimensional strain fields: 1. Failure of rocks in polyaxial, servo-control experiments. Tectonophys. 95, (1-2), 111-132 (1983).
- Ismat, Z. Evolution of fracture porosity and permeability during folding by cataclastic flow: Implications for syntectonic fluid flow. Rocky Mount. Geol. 47, (2), 133-155 (2012).
- Kwon, S., Mitra, G. Three-dimensional kinematic history at an oblique ramp, Leamington zone, Sevier belt, Utah. J. of Struct. Geol. 28, (3), 474-493 (2006).
- Casas, A. M., Simon, J. L., Seron, F. J. Stress deflection in a tectonic compressional field: A model for the northeastern Iberian chain, Spain. J. of Geophys. Res. 97, 7183-7192 (1992).
- Apotria, T. G. Thrust sheet rotation and out-of-plane strains associated with oblique ramps: An example. J. of Struct. Geol. 17, (5), 647-662 (1995).
- Hubbert, M. K. Theory of Scale Models as Applied to the Study of Geological Structures. Geol. Soc. of Am. Bull. 48, (10), 1459-1520 (1937).
- Schöpfen, M. P. J., Steyrer, H. P. Experimental modeling of strike-slip faults and the self-similar behavior. Tectonic Modeling: A volume in honor of Hans Ramberg Geol. Soc. of Am. Mem. Koyi, H. A., Mancktelow, N. 193, 21-27 (2001).
- Kwon, S., Mitra, G. Strain distribution, strain history and kinematic evolution associated with the formation of arcuate salients in fold-thrust belts: the example of the Provo salient, Sevier orogeny, Utah. Orogenic curvature Geol. Soc. of Am. Special Paper. Sussman, A., Weil, A. 383, 205-223 (2004).
- Elliott, D. The motion of thrust sheets. J. of Geophys. Res. 81, 949-963 (1976). | <urn:uuid:29ddb8cd-6aa1-4f34-b149-92970684704e> | 2.796875 | 9,323 | Truncated | Science & Tech. | 55.01709 | 95,548,441 |
Increasing energy costs and environmental concerns have emphasized the need to produce sustainable renewable fuels and chemicals1. Major efforts to this end are focused on the microbial production of high-energy fuels by cost-effective ‘consolidated bioprocesses’2. Fatty acids are composed of long alkyl chains and represent nature’s ‘petroleum’, being a primary metabolite used by cells for both chemical and energy storage functions. These energy-rich molecules are today isolated from plant and animal oils for a diverse set of products ranging from fuels to oleochemicals. A more scalable, controllable and economic route to this important class of chemicals would be through the microbial conversion of renewable feedstocks, such as biomass-derived carbohydrates. Here we demonstrate the engineering of Escherichia coli to produce structurally tailored fatty esters (biodiesel), fatty alcohols, and waxes directly from simple sugars. Furthermore, we show engineering of the biodiesel-producing cells to express hemicellulases, a step towards producing these compounds directly from hemicellulose, a major component of plant-derived biomass.
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E.J.S. was supported by the Tien Scholar Environmental Fellowship and the Synthetic Biology Engineering Research Center (SynBERC). Y.K. and G.B. were supported by a grant from LS9, Inc. (South San Francisco, California) through the University of California Discovery Grant program. This research was performed at the Joint BioEnergy Institute. We thank M. Rude with help on the manuscript and J. Cronan and the LS9 Scientific Advisory Board for technical insight and discussion.
Author Contributions E.J.S., Y.K., G.B., Z.H., A.S., A.M., S.B.d.C. and J.D.K. conceived of the experiments. E.J.S. and Y.K. constructed the strains and metabolic pathways for fatty-acid-derived products and performed the production experiments. LS9 engineered and evaluated FAEE and fatty alcohol producing strains for thioesterase evaluations. G.B. conceived, constructed and performed the xylan-metabolizing pathway growth experiments. E.J.S. and Y.K. constructed the xylan-metabolizing, fatty acid production strain and performed the production experiments. E.J.S., Y.K., A.S., S.B.d.C. and J.D.K. drafted the manuscript. All authors approved the final manuscript.
This file contains Supplementary Tables 1-2, Supplementary Figures 1-3 with Legends and Supplementary References. | <urn:uuid:308ff729-d87c-43b8-a999-f8c392a74bc3> | 2.734375 | 617 | Truncated | Science & Tech. | 51.410217 | 95,548,444 |
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It's not just science preojcts. In general, school, homework and learning can be a real struggle for many children I know this firsthand from watching my boys. Early on, I decided that my guys should never have to look far for the proper tools. Like a busy executive, they needed to concentrate on the task before them, and should have anything they need close at hand. There is a closet in our house that looks like the school supply section at Wal-Mart. The boys have tools to stay organized. They have plenty of socks, underwear, and soccer clothes. We have calculators, computers, dictionaries, encyclopedia, rulers, compasses, and yes, we keep spare science boards. (We even keep completed preojcts, as you may have read in the post about doing science preojcts with more than one kid.
- for efficient Southern detection use only positively charged nylon membrane eg. GeneScreen Plus.
- Be very careful not to physically abuse the membrane. Any scratches, scrapes, folds etc. of any kind will fail to block properly and will show a huge radioactive signal, obscuring useful information in the blot. Also be careful not to get grease from fingers, or powder from gloves on the membrane.
Preparation of Blotted Membrane
- Incubate gel to a final concentration of 1μg/ml ethidium bromide in water for at least 30 minutes with gentle agitation
- be sure to take into account the volume of the gel and the water when calculating how much ethidium to use
- for gels thicker than 6mm, increase the time for this step proportionally
- do not destain the gel
- Photograph the gel using long-wave UV (302nm - preparative setting on a transilluminator) using as brief an exposure to the additional UV light as possible to avoid over-nicking the DNA
- Expose the gel to 60 mJ/cm2 UV at 254nm (an energy setting of 600 x100μJ/cm2 on a Spectroline UV Crosslinker)
- the UV causes the ethidium to nick the DNA strands, fragmenting large pieces of DNA to sizes suitable for transfer. UV nicking is the preferred method for pulsed-field gels
- alternative nicking procedure only for standard electrophoretic gels: instead of UV exposure, nick the DNA by partial acid depurination. incubate the gel with gentle agitation in 0.25N HCl (21.5 ml concentrated HCL to 1 liter with water) for 10 minutes
- ⚠ be sure to add the acid to the water, not the other way around!
- this acid partial depurination procedure is not recommended. UV nicking is more reproducible. For pulsed-field gels, acid hydrolysis gives very inefficient transfer
- Incubate gel in denaturation solution for 30 minutes with gentle agitation.
- Rinse the gel briefly in distilled water, then incubate 30 minutes in neutralization solution.
- this brings the pH of the gel back down to neutral after the denaturation step
- Incubate the gel in 10x SSC for 15 minutes with gentle agitation
- this equilibrates the salt content of the gel closer to that of the transfer solution. If omitted, the gel can shrink and break while the transfer is happening
- Cut membrane to exact size of gel. Also cut 2 pieces of Whatman filter paper to the size of the gel, plus 2 pieces as wide as the gel, but longer (to form a wick).
- Pre-wet the membrane completely in water, then equilibrate the membrane in transfer solution.
- Fill a tray with transfer solution, place a piece of glass on the tray.
- Soak one large piece of Whatman paper in the transfer solution, place on the glass so that each end hangs down into the transfer solution, and remove bubbles by rolling with a pasteur pipette.
- Soak the second large piece of Whatman paper in transfer solution and lay on top of the first piece, again removing any bubbles by gently rolling over the paper surface with a pipette
- Place the gel on the papers on the glass, again remove bubbles.
- Cover all paper surfaces not covered by the gel with plastic wrap
- this will prevent "short-circuiting" of the transfer and ensure that all solution transfer goes through the gel (and then the membrane)
- Place the pre-wet membrane on the gel, again removing any bubbles.
- Place 2 pieces of Whatman paper pre-wet with transfer solution one-at-a-time on the membrane, removing bubbles and wrinkles for each piece.
- Place a stack of paper towels on the top Whatman papers, and apply a small weight.
- do not add a heavy weight. the goal is to ensure good contact between all the surfaces, but excessive weight can crush the gel down and inhibit transfer
- Allow to blot overnight.
- Remove the paper towels and filter paper. Mark the wells of the gel on the membrane with pencil.
- don't use pen or markers as the ink tends to dissolve in the hybridization solution
- Rinse the membrane in 2x SSC
- DO NOT ALLOW THE MEMBRANE TO DRY OUT
- The membrane can be left prehybridizing (see below) or can be left in the 2x SSC solution at room temperature if necessary. Allowing the membrane to dry out can reduce subsequent hybridization by about 5-fold, due to over-adherence of the DNA to the positively charged membrane.
- Crosslink the DNA to the membrane by exposing the damp membrane to 5 mJ/cm2 UV at 254nm (an energy setting of 50 x100μJ/cm2 on a Spectroline UV Crosslinker)
- this step is optional, but may decrease background or increase signal in some circumstances
Hybridization of DNA
- Prehybridize the membrane in hybridization solution for at least 30 minutes at 65C.
- one effective method is to prehyb with the DNA side of the membrane facing into the solution for 10 mintutes, then reverse the membrane orientation to prehybridize with the non-DNA side of the membrane facing into the solution for 10 minutes, then finally reverse orientation again and prehybridize with the DNA side of the membrane facing into the solution for at least an additional 30 minutes.
- do all of these prehybridization steps at 65C
- the goal is to block non-specific binding sites on the membrane efficiently on both sides of the membrane
- Label your probe while the membrane is prehybridizing. Use 10 - 15 ng probe per membrane if RadiolabelingDna by random priming.
- Pour off the hybridization solution and add fresh, prewarmed PEG-hyb solution.
- for large roller hybridization tubes, use 10 ml PEG-hyb. do not use an excessive volume of PEG-hyb solution
- Add the probe and hybridize at 65C overnight.
- Pour off the hybridization solution into the radioactive waste.
- Rinse membrane at 65C as follows:
- 5 minutes: rinse solution A
- 30 minutes: rinse solution A
- 30 minutes: rinse solution B
- 30 minutes: rinse solution B
- 30 minutes: rinse solution C
- Do a final brief rinse of the membrane with a 2x SSC solution (1:10 dilution of a 20x SSC stock) and wrap in Saran Wrap. Make sure the membrane is not wet (place on dry filter paper for a few minutes until all visible liquid has been absorbed) but do not allow the membrane to dry completely or it will be impossible to strip and reprobe.
- Expose and develop a series of autoradiographs.
Stripping a southern blot
If you need to strip off hybridized DNA so that a blot can be reprobed, incubate the membrane at 95C for 1 hour in 100 ml of 0.1% SDS in water (no SSC). Then begin again from the Hybridization of DNA
section above, beginning with the prehybridization step.
mix components together and heat to 50C to get the casein to dissolvestore at room temperature
- 2x SSC
- 7% SDS
- ⚠ use caution and a mask when weighing out large quantities of SDS powder. the fines are very irritating when inhaled → you should believe this
- 0.5% Hammersten casein
store at room temperature
- 2x SSC
- 7% SDS
- 0.5% Hammersten casein
- 8% PEG-6000
transfer solution - 10x SSC
Final 10x concentration is 1.5 M for NaCl and 150 mM for sodium citrate.
- Dissolve 87.7 g of NaCl and 44.1 g of sodium citrate dihydrate in 800 ml H2O.
- Adjust to pH 7.0 with HCl if necessary (but it won't in fact be necessary).
- Adjust volume to 1 liter.
- 1 liter is generally sufficient for one Southern blot
denaturation solution - 0.4N NaOH, 1.5M NaCl
per 200 ml (enough for one gel):
- 3.2 g of NaOH pellets
- 17.6 g NaCl
- bring up to 200 ml volume with water, dissolve using a stir-bar until no solid NaOH is visible
- one southern blot requires about 200 ml of denaturation solution
neutralization solution - 1M Tris pH 8.0, 1.5M NaCl
- dissolve 17.6 g NaCl in 200 ml of 1M Tris pH 8.0
- one gel requires about 200 ml of neutralization solution
- this solution must be pH 8.0. Use pH paper to check and be sure.
rinse solution A
- 2x SSC (a 1:10 dilution from a 20x SSC stock solution)
- 0.1 % SDS (a 1:100 dilution from a 10% SDS stock solution)
rinse solution B
rinse solution C
- This protocol cannot be used for NorthernBlotting since the hydroxide will destroy RNA.
- The Whatman paper can become very fragile when wet with the transfer solution. If this is a problem, do not wet the very edges of the paper and handle the wet paper by these dry edges for easier manipulations.
- It is very important for pretty results that as each layer of the southern blotting sandwich is added (wick, gel, membrane, wet filter paper) that all bubbles (including pockets of buffer) and wrinkles are carefully removed. each layer should lie completely flat upon the layer immediately below it. do not go to all the trouble to do a southern blot and then get an ugly result by scimping on this step.
- For pulsed-field gels, do not use acid depurination to nick DNA as this has been shown to reduce subsequent hybridization from pulsed-field gels when the target band is present in isolation from background non-target DNA.
- Leach TJ, Glaser RL., Quantitative hybridization to genomic DNA fractionated by pulsed-field gel electrophoresis. Nucleic Acids Res. 1998 Oct 15;26(20):4787-9.
- Lee H, Birren B, Lai E, Ultraviolet nicking of large DNA molecules from pulsed-field gels for southern transfer and hybridization. Analytical Biochemistry 1991 199:29-34.
- see http://www.millipore.com/publications.nsf/docs/tn055 for many informative technical comments
- making the hybridization solution with a final concentration of 8% PEG 6000 can greatly increase sensitivity | <urn:uuid:47af1e5e-fd5f-4ef2-b9c9-e7542b1263f6> | 2.703125 | 2,529 | Tutorial | Science & Tech. | 56.85749 | 95,548,445 |
How do organisms evolve into individuals that are distinguished from others by their own personal brain structure and behaviour? Scientists in Dresden, Berlin, Münster, and Saarbrücken have now taken a decisive step towards clarifying this question.
In an environment with many stimuli, mice experience it differently. In one mouse (right) it leads to many new neurons (black dots), while in another mouse (left), significantly fewer new neurons develop.
© CRTD / DZNE / Freund
Using mice as an animal model, they were able to show that individual experiences influence the development of new neurons, leading to measurable changes in the brain. The results of this study are published in Science on May 10th. The DFG-Center for Regenerative Therapies Dresden - Cluster of Excellence at the TU Dresden (CRTD), the Dresden site of the German Center for Neurodegenerative Diseases (DZNE), and the Max Planck Institute for Human Development in Berlin played a pivotal role in the study.The adult brain continues to grow with the challenges that it faces; its changes are linked to the development of personality and behaviour. But what is the link between individual experience and brain structure? Why do identical twins not resemble each other perfectly even when they grew up together? To shed light on these questions, the scientists observed forty genetically identical mice that were kept in an enclosure offering a large variety of activity and exploration options.
ContactProf. Dr. Gerd Kempermann
Prof. Dr. Gerd Kempermann | GFZ Potsdam
Scientists uncover the role of a protein in production & survival of myelin-forming cells
19.07.2018 | Advanced Science Research Center, GC/CUNY
NYSCF researchers develop novel bioengineering technique for personalized bone grafts
18.07.2018 | New York Stem Cell Foundation
A new manufacturing technique uses a process similar to newspaper printing to form smoother and more flexible metals for making ultrafast electronic devices.
The low-cost process, developed by Purdue University researchers, combines tools already used in industry for manufacturing metals on a large scale, but uses...
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
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Among the axioms upon which the thermodynamics of continuous bodies is based in Lecture 2, the equation of balance of energy (1.7) and the Clausius-Duhem inequality (2.50) play the most important roles. In postulating (1.7) and (2.50) one necessarily has to treat the energy, entropy, and the absolute temperature occurring in these relations as primitive quantities whose meaning is clarified only through their consequences. Although this procedure is completely satisfactory from the logical point of view, the traditional pattern of presenting thermodynamics is different: energy, entropy, and absolute temperature are claimed to be derived from verbal statements of the “laws of thermodynamics”. The arguments given in textbooks do not meet standards of rigor, but the program of founding thermodynamics upon postulates conceptually simpler than (1.7) and (2.50) is appealing. In this appendix we outline an approach to thermodynamics in which the existence of energy, entropy, and absolute temperature is rigorously proved.
KeywordsVerbal Statement Elastic Body Cyclic Process Rational Mechanics Primitive Concept
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- M. ŠILHAVŶ, “On the Clausius inequality”, Lecture at EUROMECH 111 Symposium,Constitutive Modelling in Inelasticity, Mariánské Lázn, September 26–28, 1978, page 68.Google Scholar
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We study transverse impacts of rigid objects on a free membrane. The thin elastic sheet is made of natural rubber. After impact, two distinct waves propagate in the sheet. First a tensile wave travels at the speed of sound leaving behind the wave front a stretched domain. Then a flexural wave propagates in the stretched area at a lower speed. In the stretched area geometrical confinement induces compressive circumferential stresses. They trigger a buckling instability giving rise to radial wrinkles. In this paper we report on an experimental and theoretical study of this dynamic wrinkling.
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Nearly every compound of silicon has this element in the +4 oxidation state. In contrast, most compounds of lead have this element in the +2 oxidation state.
a) What general trend of the oxidation states does this observation illustrate?
b) What could you suggest as an explanation for this observation?© BrainMass Inc. brainmass.com July 22, 2018, 12:20 pm ad1c9bdddf
(a) The general trend of the oxidation states indicate that for group 4A elements, the +4 oxidation state can exist for all elements, but it may not necessarily be the most stable. Silicon is stable at +4 and is covalent. Lead can exist with an oxidation ...
The solution is given in explanations with a total of 150-200 words. | <urn:uuid:796d4eb0-4794-428e-aff2-9db87443ec99> | 3.078125 | 161 | Q&A Forum | Science & Tech. | 62.735 | 95,548,498 |
In Hoi Ha Wan, Hong Kong, an attached fungiid coral Lithophyllon cf. edwardsi , which is normally encountered as a rare or occasional coral species growing in crevices, spreads over the rocky substrate occupying 38% of the coral cover (29% of the total area) with 33 other coral species present. It was found that the greatest number of colonies, the greatest area, and the largest colonies favoured the horizontal growing position, and L. cf. edwardsi is able to overgrow all the other corals encountered without aggression or signs of "digestive dominance". The reasons for this phenomenon are discussed.
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The Python Tutorial¶
Python is an easy to learn, powerful programming language. It has efficient high-level data structures and a simple but effective approach to object-oriented programming. Python’s elegant syntax and dynamic typing, together with its interpreted nature, make it an ideal language for scripting and rapid application development in many areas on most platforms.
The Python interpreter and the extensive standard library are freely available in source or binary form for all major platforms from the Python Web site, https://www.python.org/, and may be freely distributed. The same site also contains distributions of and pointers to many free third party Python modules, programs and tools, and additional documentation.
The Python interpreter is easily extended with new functions and data types implemented in C or C++ (or other languages callable from C). Python is also suitable as an extension language for customizable applications.
This tutorial introduces the reader informally to the basic concepts and features of the Python language and system. It helps to have a Python interpreter handy for hands-on experience, but all examples are self-contained, so the tutorial can be read off-line as well.
For a description of standard objects and modules, see The Python Standard Library . The Python Language Reference gives a more formal definition of the language. To write extensions in C or C++, read Extending and Embedding the Python Interpreter and Python/C API Reference Manual . There are also several books covering Python in depth.
This tutorial does not attempt to be comprehensive and cover every single feature, or even every commonly used feature. Instead, it introduces many of Python’s most noteworthy features, and will give you a good idea of the language’s flavor and style. After reading it, you will be able to read and write Python modules and programs, and you will be ready to learn more about the various Python library modules described in The Python Standard Library .
The Glossary is also worth going through.
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The Python Software Foundation is a non-profit corporation. Please donate.
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Three proteins – Oct4, Sox2 and Nanog -- had previously been considered the "master" regulators of embryonic stem cells, but "Ronin could be as important as these three," said Dr. Thomas Zwaka, assistant professor in the Stem Cells and Regenerative Medicine (STaR) Center at BCM. In fact, he said, if the action of Oct4, considered the most important, is reduced in embryonic stem cells, Ronin can compensate for the loss.
Embryonic stem cells are pluripotent, meaning they have the potential for becoming all other kinds of cells in the body. They are also capable of self-renewal. Oct4, Sox2 and Nanog were previously thought the major method by which embryonic stem cells remained in their pristine state. Now, Ronin represents a different and parallel pathway to achieve the same result.
Ronin is also expressed in early embryonic development of mice. If it is not present, the embryos die, said Zwaka. It is also found in mature oocytes or egg cells.
"Ronin is a potent transcription repressor," he said. In fact, it prevents the action of genes that promote the differentiation of cells into the various tissues and organs of the body.
"It does it more effectively than the other three factors together," he said. It silences the differentiation genes epigenetically through specific chemical mechanisms that modify histones, the chief packaging proteins for DNA.
He and his colleagues found Ronin as a follow-up to an earlier study that showed a component of the cell death system called caspase-3 actually cleaved and reduced the amount of Nanog protein. This caused the embryonic stem cells to stop self-renewal and begin differentiation into other kinds of cells.
Zwaka and his colleagues searched for other proteins affected by the caspase and found Ronin, which was previously unknown.
The finding prompts other questions. Can Ronin be used to reprogram differentiated cells into those that more closely resemble embryonic stem cells? What is the significance of the portion of Ronin that resembles a "jumping gene" or transponson called P element transposase, usually found in the genomes of fruit flies?
Ronin is also found in areas of the brain such as the hippocampus and the Purkinje cells of the cerebellum.
"What role does it play in the brain?" asked Zwaka.
Scientists uncover the role of a protein in production & survival of myelin-forming cells
19.07.2018 | Advanced Science Research Center, GC/CUNY
NYSCF researchers develop novel bioengineering technique for personalized bone grafts
18.07.2018 | New York Stem Cell Foundation
A new manufacturing technique uses a process similar to newspaper printing to form smoother and more flexible metals for making ultrafast electronic devices.
The low-cost process, developed by Purdue University researchers, combines tools already used in industry for manufacturing metals on a large scale, but uses...
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
20.07.2018 | Power and Electrical Engineering
20.07.2018 | Information Technology
20.07.2018 | Materials Sciences | <urn:uuid:7afc4871-76c1-4854-94e3-1b20f50c8374> | 2.828125 | 1,080 | Content Listing | Science & Tech. | 41.908632 | 95,548,608 |
High-contrast imaging (HCI) with JWST will allow observers to obtain images of faint sources located near bright point sources.
Main articles: NIRCam Coronagraphic Imaging, MIRI Coronagraphic Imaging, NIRISS Aperture Masking Interferometry
See also: NIRCam Coronagraphic Recommended Strategies, NIRISS AMI Recommended Strategies, NIRCam Coronagraphy Science Use Case, MIRI Coronagraphy Science Use Case, NIRISS AMI Science Use Case
High-contrast imaging (HCI) is used to obtain images of faint sources ("companions") located near bright, point sources ("hosts"). Typical hosts are stars and quasars. Companions include exoplanets, circumstellar structures of gas and dust, and luminous feeding zones around supermassive black holes. In normal imaging, the image of a faint companion could be swamped and lost in the noise of diffracted light in the wing of the host's image. HCI strategies—comprising special optics, observing procedures, and post-processing—are designed to reduce the impact of host light at the position of the companion, in order to make the companion detectable against the residual noise.
In HCI, the reduction of wing light from the host occurs in two steps: optical cancellation and image subtraction. Optical cancellation is achieved by special optics—pairs of masks located on the focal and pupil planes. Image subtraction is performed in post-processing by differencing a scaled PSF reference image and a science image (see PSF-subtraction strategies).
JWST offers 3 HCI designs for optical cancellation—2 types of coronagraph and one interferometer (see HCI Optics). Subsets of these designs are implemented in 3 JWST instruments:
- Lyot coronagraph (LYOT; 5 implementations in NIRCam, one in MIRI)
- 4-quadrant phase mask coronagraph (4QPMC; 3 implementations in MIRI)
- aperture masking interferometer (AMI; one implementation in NIRISS)
The instrument-specific modes for HCI, including allowed mask-filter combinations, are described at:
For more detailed information about JWST HCI options, see the references listed below.
JWST high-contrast imaging articles
Beichman, C. A., et al. 2010, PASP, 122:162
Imaging Young Giant Planets from Ground and Space
Boccaletti, A. et al. 2015, PASP, 127, 633
The Mid-Infrared Instrument for the James Webb Space Telescope, V: Predicted Performance of the MIRI Coronagraphs
Greenbaum, A.Z., Pueyo, L., Sivaramakrishnan, et al. 2015, ApJ, 798, 68
An Image-Plane Algorithm for JWST's Non-Redundant Aperture Mask Data
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|Debugging with GDB|
There are only a few basic constructs allowed in the Readline init file. Blank lines are ignored. Lines beginning with a ‘#’ are comments. Lines beginning with a ‘$’ indicate conditional constructs (see Conditional Init Constructs). Other lines denote variable settings and key bindings.
setcommand within the init file. The syntax is simple:
set variable value
Here, for example, is how to
change from the default Emacs-like key binding to use
vi line editing commands:
set editing-mode vi
Variable names and values, where appropriate, are recognized without regard to case. Unrecognized variable names are ignored.
Boolean variables (those that can be set to on or off) are set to on if the value is null or empty, on (case-insensitive), or 1. Any other value results in the variable being set to off.
A great deal of run-time behavior is changeable with the following variables.
insert-commentcommand is executed. The default value is
self-insert. The default is ‘off’.
editing-modevariable controls which default set of key bindings is used. By default, Readline starts up in Emacs editing mode, where the keystrokes are most similar to Emacs. This variable can be set to either ‘emacs’ or ‘vi’.
next-history. The default is ‘off’.
meta-flagis a synonym for this variable.
viis equivalent to
emacsis equivalent to
emacs-standard. The default value is
emacs. The value of the
editing-modevariable also affects the default keymap.
mark-directories). The default is ‘off’.
more-like pager to display a screenful of possible completions at a time. This variable is ‘on’ by default.
accept-lineis executed. By default, history lines may be modified and retain individual undo lists across calls to
readline. The default is ‘off’.
Once you know the name of the command, simply place on a line in the init file the name of the key you wish to bind the command to, a colon, and then the name of the command. There can be no space between the key name and the colon – that will be interpreted as part of the key name. The name of the key can be expressed in different ways, depending on what you find most comfortable.
In addition to command names, readline allows keys to be bound to a string that is inserted when the key is pressed (a macro).
Control-u: universal-argument Meta-Rubout: backward-kill-word Control-o: "> output"
In the above example, C-u is bound to the function
M-DEL is bound to the function
C-o is bound to run the macro
expressed on the right hand side (that is, to insert the text
‘> output’ into the line).
A number of symbolic character names are recognized while
processing this key binding syntax:
"\C-u": universal-argument "\C-x\C-r": re-read-init-file "\e[11~": "Function Key 1"
In the above example, C-u is again bound to the function
universal-argument (just as it was in the first example),
‘C-x C-r’ is bound to the function
and ‘<ESC> <[> <1> <1> <~>’ is bound to insert
the text ‘Function Key 1’.
The following gnu Emacs style escape sequences are available when specifying key sequences:
In addition to the gnu Emacs style escape sequences, a second set of backslash escapes is available:
When entering the text of a macro, single or double quotes must be used to indicate a macro definition. Unquoted text is assumed to be a function name. In the macro body, the backslash escapes described above are expanded. Backslash will quote any other character in the macro text, including ‘"’ and ‘'’. For example, the following binding will make ‘C-x \’ insert a single ‘\’ into the line: | <urn:uuid:7ec4805e-281c-4f12-9b3c-b55bc763bda7> | 2.609375 | 923 | Documentation | Software Dev. | 51.61422 | 95,548,638 |
Solar Wind Speed
Updates: every 10 minutes
(last updated 17 Jul 2018 22:57 UT)
Solar Wind Parameters Used: Date: 17 07 2018 2248 UT Velocity: 425 km/sec Bz: 0.0 nT Density = 6.0 p/cc Calculated Information from Solar wind parameters: Magnetopause Stand Off Distance = 11.5Re Solar Wind Dynamic Pressure Dp = 0.90nPa
The above diagram indicates solar wind speed and strength of the interplanetary magnetic field (IMF) in a north/south direction. Higher solar wind speeds and strong south pointing (negative) IMF are associated with geomagnetic storms on earth. The red area on the image indicates an approximate region in which disturbed conditions might be expected.
The plots on this page were produced from data supplied by the US NOAA Space Weather Prediction Center (SWPC). This Real Time Solar Wind (RTSW) data set originates from NASA's Deep Space Climate Observatory (DSCOVR) satellite. The above image shows with a black square the value of the solar wind speed (horizontal) axis and the strength of the interplanetary magnetic field in a north/south direction (Bz - vertical axis). Higher solar wind speeds and strong south pointing (negative) interplanetary magnetic field are associated with geomagnetic disturbances on earth. The red area on the image indicates an approximate region in which disturbed conditions might be expected. The coloured dot within the black square, is an indicator of solar wind density, and is yellow when density exceeds 10 particles per cubic cm, red when density exceeds 15 particles per cubic cm, otherwise green.
The DSCOVR spacecraft is positioned at the L1 point between the Earth and the sun and gives approximately one hour advance notice of conditions on Earth. This typical lead time decreases with faster solar wind speeds associated with coronal mass ejections.
The solar wind magnetic field, can be measured in three compoenents, Bz, Bx, and By. Bx lies along the Sun-Earth line, with Bz and By defining a vertical plane (the clock "face"). The solar wind clock angle is the angle produced from the vector sum of By and Bz.
The image below shows recent trends in solar wind speed and interplanetary magnetic field north/south direction. | <urn:uuid:c63406d8-f70d-427a-b3b2-a86bf7f07d63> | 2.859375 | 478 | Knowledge Article | Science & Tech. | 47.40928 | 95,548,649 |
Electrical Properties & Quantum Transport in Nanowire Device
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Disclaimer: This essay has been submitted by a student. This is not an example of the work written by our professional essay writers. You can view samples of our professional work here.
Any opinions, findings, conclusions or recommendations expressed in this material are those of the authors and do not necessarily reflect the views of UK Essays.
- David S. Murdoch
Nanowires are quasi one-dimensional rod-like nanostructures with diameters in the order of nanometres (10^-9m) and have seemingly unlimited length and a great degree of versatility. Nanowires form as monocrystals in a well defined crystal geometric direction. Nanowire geometry allows for easy contacting of the wires from two sides. Attention is devoted to geometry of nanowires because this is the feature that allows for easy control of electronic properties of nanowires. Growth orientation (e.g. 100), the faceting arrangement (e.g. ) and the surface structure (Si(100)) are generally outlined in nanowire investigations and are a generally accepted notation to depict nanowires. A nanowire is thin and diameter is in order of magnitude far smaller than length of nanowire. As diameters gets larger, quantum effects become less significant against bulk material properties.
Nanowires have thermoelectric properties, specifically that they have high thermal stability and low thermal conductivity. Quasi one dimensional Carbon Nanotubes (CNTs) and nanowires are likely composite materials for future electronic devices. Nanowires electrical properties are easier to control than CNTS, therefore are an attractive alternative to CNTs and naturally passivated when semiconducting.
Under scrutiny, experimentally grown nanowires always have passivated facets but further study of unpassivated (pristine) nanowires has demonstrate fundamental mechanisms at an atomic-scale. One of which being that passivation is necessary to obtain nanowires with those controllable electrical properties.
Semiconductor nanowires can form from materials such as:
- Silicon, Si
- Indium Arsenide, InAs
- Germanium, Ge
- Indium Phosphide, InP
- Gallium Nitride, GaN
- Zinc Oxide, ZnO
- Cadmium Sulphide, CdS
Nanowires can also be made from metallic materials and oxidised to make insulators but semiconducting crystalline nanowires are ultimately more useful in devices. At the atomic-scale, although impurities are useful sometimes, small variations can cause serious unwanted alterations to electronic structure.
Semiconducting nanowires are often fabricated via growth mechanisms or synthesised by electrochemical etching. These processes are often done in an aqueous solution with HF acid. The most common method of nanowire growth is Vapour-Liquid-Solid (VLS) mechanism. VLS is a bottom-up process that starts with the dissolution of gaseous semiconducting materials with colloids of a metal catalyst, generally gold or silver . The one-dimensional growth is evoked and dictated by the colloids. Once the colloids are supersaturated with semiconducting material, crystalline nanowire growth will start to occur at a boundary between solid substrate and liquidised material. This particular description was the growth of silicon nanowires.
One example of EE is the use Ag catalyst on wafer-scale Si to fabricate a nanowire array. Ag+ ions are reduced in the solution after holes are inserted into the valence band of Si substrate. The reduced Ag nanoparticles dictate the extent of the etching and oxidation processes. Vertically aligned nanowires result from this synthesis.
After both methods of fabrication, nanowires remained anchored to substrates and are similarly dependent upon length of diameter for thermoelectric properties. However, wires from EE have much rougher surfaces than that of VLS.
[Si nanowires yielded from EE have much rougher surfaces than typical Si nanowires grown via VLS and have less thermal conductance.
A heterostructures are the junctions between two different crystalline semiconductor materials essentially two different nanowire materials formed together to make one nanowire with unique properties. Heterostructures are commonly grown via VLS. These heterostructures allow nanowires to have multitude of properties.
What is a semiconductor and how does it work. By strict definition, a semiconductor has a conductivity between 105 and 10-5Ω-1m-1. This is in contrast with insulators that have conductivity of approximately 10-24Ω-1m-1 and metals that typically have 107 to 108Ω-1m-1. On the face of them, these numerical values are rather meaningless but they do show that a semiconductor is separate from the other two, a true genuine third category of material.
How a semiconductor conducts is best described by a conduction and valence band. The conduction band rests above the valence band. The conduction band contains excited electrons and the valence band contains holes. In an insulator the two bands are a vast distance away from each other. In a semiconductor the two bands are much closer together, almost touching. If a bandgap is small enough, thermal vibrations may provide enough energy for some electrons to excite from the valence band to the conduction band. In a metal the two bands overlap, leading to a low resistivity in metals. The diagram below depicts what the above description.
An intrinsic semiconductor has a completely filled valence band, electron and hole populations are always equal. An extrinsic semiconductor is doped. Midway between the two bands lies the Fermi energy. Below the Fermi energy. At absolute zero, no electrons we be able to excite past the Fermi energy. In n-type and p-type semiconductors, the Fermi energy is adjusted to be closer to valence or conduction band. Between the two bandgaps there is a sea of electron density.
A transistor is a semiconducting electronic switch and are commonly found embedded in integrated circuits. Down-scaling of the gate length over the years has technological devices reduce in size has caused field-effect devices to having significantly less electrostatic control of a path of conductance; more capable device have been developed such as FINFETs, Trigate transistors and ultimately gate-all-around devices (GAA).
Nanowire devices can come in all shapes, not sizes. Examples of nanowire devices are Field-Effect Transistors (FETS), LEDs, Tunnelling diodes, Elementary logic gates, lasers and biochemical sensors.
There are a number of different FETs but Metal-Oxide-Semiconductor Field-Effect Transistors (MOSFETs) might be the most interesting or relevant in near-future technologies and are examples of GAAs. MOSFETs are extrinsic semiconductors where the doped material has been oxidised for some insulating properties. If a metallic gate anode were deposited you have the foundation of an electrical switch. [crystalline] Carrier charge density can be changed at the Fermi energy. If the semiconductor were p-type (i.e. abundance of holes in valence band) and a positive voltage is applied to the circuit then the electrostatic energy of the holes increases. Although holes are pushed away from the anode, any attracted electrons do not compensate for the decrease in positive charge. The switching effect is reduced if charge can be stored at the interface between the insulating barrier and the Si since the potential of the silicon will be less than that of the applied gate.
When voltage is increased beyond a certain point electron concentration at the surface of the Si will exceed the hole concentration. This creates the on/off switching effect. This gate voltage is large enough so that the bottom of the valence band moves down. The switching effect does not work with a metallic material because the valence band would be too high still and a Fermi energy could still carry current. The semiconductor band gap controls on/off electron currents.
Are nanowire MOSFETs superior? Smaller semiconductor gates allows speeds up operation from shorter distances, lower areas of capacitances and Larger fields but it is risky to store charge in a transistor so small and new quantum effects come into play at a nanowire-scale. One of the capabilities of these new technologies is to produce potentials which can confine electrons to the same scale as their Fermi wavelength. Nanowire MOSFETs can also be used in high frequency circuits.
In Electron microscopy high energy electrons are fired at an object and reflected electrons are collected and computed into an image. Electron microscopy generally has greater magnifying power than optical microscopes. There are two main electron microscopes and they are Transmission Electron Microscopy (TEM) and Scanning Electron Microscopy (SEM). SEM uses secondary electron to help generate an image that gives the viewer an impression of 3D while TEM fires at thinner objects at produces a 2D image but while ultimately be more useful for imaging nanowires.
Larger batteries potential differences require more conductive metals. In recent years Lithium has grown popular as a cathode. Semiconducting Si could be an attractive anode for Li cathode batteries as both metals become more ubiquitous. Although Si has low discharge potential and charge capacity 10x higher than existing graphite anodes and even more so than oxide and nitride materials, Si anodes in bulk form have limited use because silicon's volume is drastically altered during extraction and insertion of Li. Resulting in capacity fading and pulverisation after recharging cycles. This is depicted in the diagram below.
Anodes made of Si films have a stable capacity over many cycles but are not viable as a battery because they waste away over time. Nanowire are a superior alternative to bulk materials because of a piezoelectric effect: “Crystals which acquire a charge when compressed, twisted or distorted are said to be piezoelectric. This provides a convenient transducer effect between electrical and mechanical oscillations.” Each Si nanowire is grown and electrically connected to a metallic substrate surface thus all nanowires contribute to the battery capacity.
During Fossil fuel combustion 15 TW of heat is lost to the environment. Thermoelectric modules could potentially convert part of the heat waste to electricity. As of 2008, Bi2Te3 in its bulk form was the most commonly used material for thermoelectric devices. However, it is difficult to scale bulk Bi2Te3 to large-scale energy conversion in power plants but fabricating synthetic nanostructures of Bi2Te3 for this purpose is even more difficult and expensive. Thus, Bi2Te3 is replaced with increasingly ubiquitous Si.
Ubiquitous Si, abundance with a low-cost and high-yield products thanks to economies of scale. Si also has advantages in thermoelectric applications. Critical spacings below 300nm in Si would reduce thermal conductivity since Si has larger differences in mean free path lengths between phonons (~300nm) and electrons (110nm) at room temperature.
InAs-based semiconductor nanowires can already provide a convenient basis for the development of more complex hybrid nanostructures and can contact Schottky barrier-free with metals.The InAs superconducting nanowires are fabricated via catalytic process based on the VLS mechanism. InAs nanowires can be grown epitaxially. Epitaxial growth means the deposited material continues to grow on the same crystalline lattice as its substrate.
A superconductor is material with with no resistance and generally operates at a lower temperature. Within semiconductors, there are electron pairs, separated by vast distance in comparison to the lattice spacing, are coupled. These so-called Cooper pairs can exhibit boson characteristics and condense to a ground state since their attraction produces a small pair binding energy similar to the Fermi energy level.
A supercurrent generates no waste heat or any other form of waste. The supercurrent can be switched on or off by the electron density acting like a transistor as described earlier. Nanowires acquire superconducting properties because of the proximity effect, a phenomenon that can occur as Cooper pairs of electrons from a superconductor flow into a normal conductor at a junction. Nanowires aren't inherently superconducting or easy to make superconducting. The proximity effect manifests itself through the appearance of a supercurrent, which can be viewed as a consequence of the diffusion of Cooper pairs throughout the entire length of the nanowire section between the two superconducting electrodes. the proximity affect can only happen if the boundary between Superconductor and semiconductor allows electrons to move freely. Cooper pair tunnelling is an explanation of Cooper pairs where they are able to interact through quantum tunnelling. At a junction between two superconductors and a more resistive material i.e. S-N-S junction. Two Cooper pairs across from each other in two separate semiconductors, can feel an attraction and readily flow into the normal conductor dividing them. S-N-S junctions will also feel a Josephson effect. Cooper pair could be created in the superconductor electrons in the Fermi energy being reflected at the S-N boundary. This could be because of tunnelling effects.
But what of Tunable supercurrent? How can a hybrid superconductor-semiconductor device work to observe quantum phenomena? Josephson behaviour occurs at critical currents. The nanowires allows the critical current to be controlled by voltage at a gate, Vg. If this voltage is negative then electron density is reduced and nanowires perform as the weak links between tunable superconductors. With the use of certain geometries, there is the possibility of controlling individual nanowires on the same IC.
Majorana fermions are particles that are their own antiparticle. Not much is still known about Majorama pairs, not all the theory has been made to explain them and their properties yet. They are also examples of non-Abelian anyons. In the vicinity of a Zeeman field, semiconducting nanowires require strong spin-orbit to induce majorana pairing in between electron states. This proximity effect induces a topological superconductor. Majoranas can be detected by Tunnelling Spectroscopy. A superpostion of Majorana particles states will always be zero energy because the particle and antiparticle have opposite energy. Said zero energy state can be found in a normal conductor acting as a junction.
How to summarise this dissertation? The task received was to research and review electrical properties and quantum transport in nanowire devices. This task down into an explanation of base nanowires, specifically semiconducting nanowires. Then, general devices such as transistors, batteries and thermoelectrics were reported on and how certain applications have taken advantage of nanowires in respective devices. Then analyse of quantum effects in Cooper Pairs in superconductors and Majorama fermions. Technology is advancing at an exponential pace. The smaller components can be the more attractive they to companies who manufacture and sell consumer products. The smaller a transistor is the more you can fit on an integrated circuit leading to smaller more powerful products. Majorama fermions and Cooper pair tunnelling probably won't be used in any consumer applications in the near future but nanowire semiconductors in junctions placed between superconductors show means of electrically measuring quantum tunnelling. In the near future investigations of these particles will enhance fabrication and measuring techniques and eventually manipulate and control Majorana qubits. They are examples of non-Abelian anyons, quantum state after partilce exchange making them ideal for use in topological quantum computing.
- R. Rurali, “ Structural, electronic, and transport properties of silicon nanowires”, Reviews Of Modern Physics, 82 427-449 (2010)
- Law, M., Goldberger, J., Yang, P. D., “Semiconductor Nanowires and Nanotubes”, Annual Review of Materials Research, 34, 83-122 (2004)
- Hochbaum, R. Chen, R. D. Delgado, W. Liang, E. C. Garnett, M. Najarian, A. Majumdar, P. Yang, “Enhanced thermoelectric performance of rough silicon nanowires”, Nature 451, 163-167 (2008)
- Crystalline Solids lecture notes http://cxs.phys.soton.ac.uk/mwf/mediawiki-1.21.2/images/7/70/2013_lecture_notes.pdf
- Egard M, Johansson S, Johansson AC, Persson KM, Dey AW, Borg BM, Thelander C, Wernersson LE, Lind E, “Vertical InAs nanowire wrap gate transistors with f(t) > 7 GHz and f(max) > 20 GHz”, Nano Lett. 10, 809-812 (2010).
- Y.-J. Doh, J. A. van Dam, A. L. Roest, E. P. A. M. Bakkers, L. P. Kouwenhoven, S. De Franceschi, “Tunable Supercurrent Through Semiconductor Nanowires”, Science 309, 272-275 (2005)
- C. T. K.-H. Stadtländer, “Scanning Electron Microscopy and Transmission Electron Microscopy of Mollicutes: Challenges and Opportunities” Modern Research and Educational Topics in Microscopy, 123 (2007)
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- Piezoelectric Effect, HyperPhysics http://hyperphysics.phy-astr.gsu.edu/hbase/solids/piezo.html
- Cooper Pairs, Hyperphysics http://hyperphysics.phy-astr.gsu.edu/Hbase/solids/coop.html
- V. Mourik, K. Zuo, S. M. Frolov, S. R. Plissard, E. P. A. M. Bakkers, L. P. Kouwenhoven, “Signatures of Majorana Fermions in Hybrid Superconductor-Semiconductor Nanowire Devices”, Science 336, 1003-1007 (2012).
- Fermi Level, Hyperphysics http://hyperphysics.phy-astr.gsu.edu/hbase/solids/fermi.html
- Leijnse, M., Karsten,F., “Introduction to topological superconductivity and Majorana fermions” Topical review 1-20 (2012) http://arxiv.org/pdf/1206.1736v2.pdf
- Enter the Majorana Fermion, Sciencemag.org, http://www.sciencemag.org/content/336/6084/989.full.pdf
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To export a reference to this article please select a referencing stye below: | <urn:uuid:ef443fe0-817f-4e4a-9d20-67bd4882f21f> | 3.1875 | 4,143 | Academic Writing | Science & Tech. | 30.716583 | 95,548,658 |