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A single-crystal diamond X-ray pixel detector with embedded graphitic electrodes

The first experimental results from a new transmissive diagnostic instrument for synchrotron X-ray beamlines are presented. The instrument utilizes a single-crystal chemical-vapour-deposition diamond plate as the detector material, with graphitic wires embedded within the bulk diamond acting as electrodes. The resulting instrument is an all-carbon transmissive X-ray imaging detector. Within the instrument's transmissive aperture there is no surface metallization that could absorb X-rays, and no surface structures that could be damaged by exposure to synchrotron X-ray beams. The graphitic electrodes are fabricated in situ within the bulk diamond using a laser-writing technique. Two separate arrays of parallel graphitic wires are fabricated, running parallel to the diamond surface and perpendicular to each other, at two different depths within the diamond. One array of wires has a modulated bias voltage applied; the perpendicular array is a series of readout electrodes. X-rays passing through the detector generate charge carriers within the bulk diamond through photoionization, and these charge carriers travel to the nearest readout electrode under the influence of the modulated electrical bias. Each of the crossing points between perpendicular wires acts as an individual pixel. The simultaneous read-out of all pixels is achieved using a lock-in technique. The parallel wires within each array are separated by 50 µm, determining the pixel pitch. Readout is obtained at 100 Hz, and the resolution of the X-ray beam position measurement is 600 nm for a 180 µm size beam.




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High-efficiency ultra-precision comparator for d-spacing mapping measurement of silicon

This article describes a high-efficiency experimental configuration for a self-referenced lattice comparator with a `brush beam' of synchrotron radiation from a bending magnet and two linear position-sensitive photon-counting-type X-ray detectors. The efficiency is more than ten times greater compared with the `pencil-beam' configuration and a pair of zero-dimensional detectors. A solution for correcting the systematic deviation of d-spacing measurements caused by the horizontal non-uniformity of the brush beam is provided. Also, the use of photon-counting-type one-dimensional detectors not only improves the spatial resolution of the measurements remarkably but can also adjust the sample's attitude angles easily.




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Development of an X-ray imaging detector for high-energy X-ray microtomography

A dedicated X-ray imaging detector for 200 keV high-energy X-ray microtomography was developed to realize high-efficiency high-resolution imaging while keeping the field of view wide.




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Hard X-ray phase-contrast-enhanced micro-CT for quantifying interfaces within brittle dense root-filling-restored human teeth

Phase-contrast enhanced micro-computed tomography reveals huge discontinuities at the interfaces between dental fillings and the tooth substrate. Despite the complex micromorphology, gaps in bonding could be visualized and quantified in 3D.




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3D grain reconstruction from laboratory diffraction contrast tomography

A method for reconstructing the three-dimensional grain structure from data collected with a recently introduced laboratory-based X-ray diffraction contrast tomography system is presented. Diffraction contrast patterns are recorded in Laue-focusing geometry. The diffraction geometry exposes shape information within recorded diffraction spots. In order to yield the three-dimensional crystallographic microstructure, diffraction spots are extracted and fed into a reconstruction scheme. The scheme successively traverses and refines solution space until a reasonable reconstruction is reached. This unique reconstruction approach produces results efficiently and fast for well suited samples.




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Disorder in La1−xBa1+xGaO4−x/2 ionic conductor: resolving the pair distribution function through insight from first-principles modeling

Ba excess in LaBaGaO4 triggers ionic conductivity together with structural disorder. A direct correlation is found between the density functional theory model energy and the pair distribution function fit residual.




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Accurate high-resolution single-crystal diffraction data from a Pilatus3 X CdTe detector

Detailed analysis of the high-flux deficiencies of pixel-array detectors leads to a protocol for the measurement of structure factors of unprecedented accuracy even for inorganic materials, and this significantly advances the prospects for experimental electron-density investigations.




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Equatorial aberration of powder diffraction data collected with an Si strip X-ray detector by a continuous-scan integration method

Exact and approximate formulas for equatorial aberration of a continuous-scan Si strip detector are compared.




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Structure variations within RSi2 and R2Si3 silicides. Part II. Structure driving factors

Most articles dealing with R2TSi3 compounds are only interested in one specific composite or in a series of composites with varying T elements while keeping R fixed (or vice versa). The present work gives an overview of the complete range of 2:1:3 silicides, similar those of Hoffmann & Pöttgen (2001) and Pan et al. (2013). In contrast to the work of Hoffmann & Pöttgen (2001), reasons for formation of the different symmetries and superstructures are discussed. Here, crystallographic properties are in[the] focus, whereas physical and magnetic properties are omitted because those are given by Pan et al. (2013). READS LIKE AN ABSTRACT, please re-write and remove references if possible. Should be two sentences max.




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Synthesis and crystallographic, spectroscopic and computational characterization of the effects of O—R substituents on the torsional[torsion] angle of 3,3',4,4'-substituted bi­phenyls

The synthesis, characterization and study of structures from a series of bi­phenyls substituted at positions 3, 3', 4 and 4' with groups connected to the bi­phenyl core through oxygen atoms are presented here. The molecular conformation is extensively studied both in the solid as well as in the liquid state, and the effect of different actors (such as packing and chain length) on the torsion angle between aromatic rings is analyzed.




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Appalachian Trail survey aims hidden cameras at large predators

Describing his project of counting bears, bobcats and other predatory mammals along the Appalachian Trail, National Zoological Park wildlife ecologist William McShea looks to American literature for a comparison.

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Fossils Show Prehistoric Global Warming

For those who think that global warming is a 21st-century phenomenon, Scott Wing, a scientist at the Smithsonian’s National Museum of Natural History, has news about the past.

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Dog bones reveal ecological history of California’s Channel Islands

A recent study of dog bones excavated from archaeological sites on the Channel Islands of California has cast new light on the past ecology of the islands and the impact that domestic dogs--brought to the islands by Native Americans more than 6,000 years ago—may have once had on the islands’ animals and ecosystems.

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Scientists Determine Geese Involved in Hudson River Plane Crash Were Migratory

Scientists at the Smithsonian Institution examined the feather remains from the Jan. 15, 2009, US Airways Flight 1549 bird strike to determine not only the species, but also that the Canada geese involved were from a migratory, rather than resident, population. This knowledge is essential for wildlife professionals to develop policies and techniques that will reduce the risk of future collisions. The team’s findings were published in the journal “Frontiers in Ecology and the Environment” in June.

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Astrophysical Observatory scientists are monitoring the mysterious movements of glaciers

In southeastern Greenland, two rivers of ice named Helheim and Kangerdlugssuaq flow in spurts and starts toward the coast. They are much like any other […]

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The Smithsonian’s National Air and Space Museum opens new Public Observatory on the Mall in Washington, D.C.

The Smithsonian’s National Air and Space Museum has opened a new Public Observatory that contains a 16-inch, 3,000-pound Boller and Chivens telescope, on loan from the Smithsonian Astrophysical Observatory. Through this powerful telescope, museum visitors can now observe the sun (with a special filter), the moon and the brighter stars and planets, such as Venus, Jupiter and Saturn, during daylight hours. Funding for the project was provided by the National Science Foundation.

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Hall of Human Origins to open at Smithsonian’s Natural History Museum, March 17, 2010

A major new exhibition hall dedicated to the discovery and understanding of human origins will open next year at the Smithsonian's National Museum of Natural History: The David H. Koch Hall of Human Origins

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Strawberry dart frogs bred at National Zoo for first time in Zoo’s history

For the first time in its history, the National Zoo has bred strawberry dart frogs (Oophaga pumilio), which are known primarily for their vibrant colors and poisonous skin. These frogs also stand out among others because of their dedication to their young as they undergo metamorphosis from egg to tadpole to frog.

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Laboratory tests reveal precise way to measure vertical lift in bumblebees and other small insects and birds

Birds do it. Bees do it. And in a laboratory in northern California, scientists using bumblebees recently figured out the best way to measure it--vertical lift!

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Eighty-thousand bark beetles enter National Museum of Natural History collections

The Stephen L. Wood collection brings the collection of bark beetles held in the Natural History Museum’s Department of Entomology to an impressive 180,000 specimens, making it one of the most extensive collections in world.

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Newly discovered prehistoric turtle co-existed with world’s biggest snake

About as thick as a standard dictionary, this turtle’s shell may have warded off attacks by the Titanoboa, thought to have been the world’s biggest snake, and by other, crocodile-like creatures living in its neighborhood 60 million years ago.

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Scientists establish first frozen repository of Hawaiian coral

Unless action is taken now, coral reefs and many of the animals that depend on them may cease to exist within the next 40 years, causing the first global extinction of a worldwide ecosystem during current history.

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Chandra X-ray Observatory finds youngest nearby black hole

Astronomers using NASA's Chandra X-ray Observatory have found evidence of the youngest black hole known to exist in our cosmic neighborhood. The 30-year-old object is a remnant of SN 1979C, a supernova in the galaxy M100 approximately 50 million light years from Earth.

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Rutgers glider added to the collections of the National Museum of Natural History

The Scarlet Knight, as the glider is called, made nautical history as the first submersible glider to successfully cross the Atlantic Ocean.

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Zoo lion cub named “Aslan” by actors Georgie Henley and Skandar Keynes

National Zoo lion keeper Rebecca Stites, at right in photo, was joined by Georgie Henley, at left in photo, and Skandar Keynes, actors in the […]

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Environmental Research Center to help with Chesapeake Bay seagrass restoration

A research team from The Smithsonian Environmental Research Center and Virginia's Old Dominion University will be awarded $110,999 to develop a tool to help seagrass restorers predict which places will be the best for planting seagrasses, the Virginia Sea Grant has announced.

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Skeletal casts of early hominin ancestor from Africa donated to National Museum of Natural History

A. sediba was discovered in 2008 in the Malapa Cave at the Cradle of Humankind World Heritage Site located outside Johannesburg.

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Whale sharks featured in award-winning documentary following the work of Tropical Research Institute’s Héctor Guzman

The awarded film features STRI marine biologist Héctor M. Guzman diving with a group of five whale sharks while traveling in the Tropical Eastern Pacific. In the video, Guzmán tags a radiotransmitter to one of the sharks in order to follow its voyages.

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Leafsnap, a new mobile app that identifies plants by leaf shape, is launched by Smithsonian and collaborators

In addition to the species name, Leafsnap provides high-resolution photographs and information about the tree's flowers, fruit, seeds and bark—giving the user a comprehensive understanding of the specie

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National Museum of Natural History’s coral collection used in Caribbean agricultural and sewage pollution study

A study published in the journal Global Change Biology finds that while fertilizer has been the dominant source of nitrogen pollution in Caribbean coastal ecosystems for the past 50 years, such pollution is on the decline, thanks in part to the introduction of more advanced, environmentally responsible agricultural practices during the last decade.

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Smithsonian Conservation Biology Institute to help create frozen repository of sperm and embryonic cells for Great Barrier Reef corals

Researchers at the Smithsonian Conservation Biology Institute and partnering organizations will build a frozen repository of Great Barrier Reef coral sperm and embryonic cells. Genetic banks composed of frozen biomaterials hold strong promise for basic and applied research and conservation of species and genetic variation.

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The Carina Nebula, a local supernova factory, is ramping up production

A local supernova factory has recently started production, according to a wealth of new data from NASA's Chandra X-ray Observatory on the Carina Nebula.

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Chandra X-Ray Observatory finds massive black holes common in early universe

Using the deepest X-ray image ever taken, astronomers found the first direct evidence that massive black holes were common in the early universe. This discovery from NASA's Chandra X-ray Observatory shows that very young black holes grew more aggressively than previously thought, in tandem with the growth of their host galaxies.

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New study reveals desert tortoise is actually two distinct species

A new study shows that the desert tortoise, thought to be a single species for the last 150 years, is in fact two separate and distinct species, based on DNA evidence and biological and geographical distinctions.

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Earthquake causes minor damage to Smithsonian natural history collections

The 5.8-magnitude earthquake that shook the eastern United States on the afternoon of Tuesday, Aug. 23, caused minor damage to some of the Smithsonian's natural history collections. All public Smithsonian museums are open and have been determined safe for visitors and staff.

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New “cloud-based” storage initiative to make vertebrate research collections available worldwide

What Google is attempting for books, the University of California, Berkeley, plans to do for the world's vertebrate specimens: store them in "the cloud."

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New dinosaur species named from hatchling fossil donated to National Museum of Natural History

The fossil represents the youngest nodosaur ever discovered, and the only known specimen of a new genus and species of dinosaur that lived approximately 110 million years ago during the Early Cretaceous Era.

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What makes rainforests unique? History, not ecology.

History and geology, not current ecology, are likely what has made tropical forests so variable from site to site.

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Suitor’s gentle massage soothes aggressive, cannibalistic female spiders, researchers find

A new study by a team of scientists from the Smithsonian’s National Museum of Natural History, the National University of Singapore and the Slovenian Academy of Sciences and Arts have unlocked the secret to mate binding in orb web spiders, and revealed just how it calms the cannibalistic female spider.

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Complete evolutionary tree of the Hawaiian honeycreepers traced by Smithsonian scientists, collaborators

Smithsonian scientists and collaborators have determined the evolutionary family tree for one of the most strikingly diverse and endangered bird families in the world, the Hawaiian honeycreepers.

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New details on birth of black hole Cygnus X-1 revealed by Chandra X-ray Observatory

Astronomers are confident the Cygnus X-1 system contains a black hole, and with these latest studies they have remarkably precise values of its mass, spin, and distance from Earth.

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Smithsonian scientists help build first frozen repository of Great Barrier Reef coral

Researchers from the Smithsonian Conservation Biology Institute, Hawaii Institute of Marine Biology and other partnering organizations spent two weeks at the end of November collecting sperm and embryonic cells during spawning from two species of coral and have built the first frozen repository for the Great Barrier Reef.

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Rising seas, development are altering prehistoric artifacts in the Chesapeake’s tidal zone

As a coastal archaeologist and expert in prehistoric and historic settlement sites in the Chesapeake Bay region, Darrin Lowery of the Smithsonian’s National Museum of Natural History and University of Deleware, is carefully watching the effects of coastal erosion and rising sea levels on coastal archaeological sites.

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Why did the tortoise cross the road? A recent study indicates few do.

Scientists studying genetic variation and gene flow in a population of tortoises (Gopherus agassizii) in California’s Mojave Desert, were surprised recently to discover that two roads built in the desert in the 1970s had a noticeable impact on the population’s genetic structure.

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Chandra X-ray Observatory clocks stellar wind at 20 million mph

The fastest wind ever discovered blowing off a disk around a stellar-mass black hole has been observed by a team of astronomers using NASA’s Chandra X-ray Observatory.

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  • Center for Astrophysics | Harvard & Smithsonian
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X-ray flares observed by Chandra are asteroids being torn to pieces in a black hole

A new study provides a possible explanation for the mysterious flares. The suggestion is that there is a cloud around Sgr A* containing hundreds of trillions of asteroids and comets, which have been stripped from their parent stars.

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Meet the 125-million-year-old pollinator “Jeholopsyche liaoningensis”

Jeholopsyche liaoningensis is a new genus and species of flying insect from northeastern China, recently revealed in two new fossil specimens.

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