We’ve seen a serious series of super moons this summer and the show’s not over yet. Mark your calendars: the next one will light up […]

The post Cutting through the dust: Radar shows moon’s true face for first time appeared first on Smithsonian Insider.

Admired from afar by the ancient Romans, the moon was once deified as a goddess, Luna. Today, two-thousand years later, geologists who scrutinize the moon’s […]

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Images obtained by NASA’s MErcury Surface, Space ENvironment, GEochemistry and Ranging (MESSENGER) spacecraft during the low-altitude orbital phase of the mission have revealed previously undetected […]

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To the Hopewell Culture, ancient Native Americans who sought out the exotic from near and far, metal was a rare and precious resource. Copper, found […]

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Monday, Aug. 21 was an unusual day across North America. Early in the morning, families, colleagues and tourists were searching for special solar glasses with […]

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As average annual temperatures increase, mosquitoes have also been on the move—up the mountains of the Hawaiian islands. Once a refuge for native birds susceptible […]

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To get a better idea of just what is going on with the current volcanic eruption of Kilauea on the island of Hawaii, take a […]

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Seven corrections are made and several supplementary equations are added to the article by Yoshimura [Acta Cryst. (2015), A71, 368–381].

Structural investigations of amorphous and nanocrystalline phases forming in solution are historically challenging. Few methods are capable of in situ atomic structural analysis and rigorous control of the system. A mixed-flow reactor (MFR) is used for total X-ray scattering experiments to examine the short- and long-range structure of phases in situ with pair distribution function (PDF) analysis. The adaptable experimental setup enables data collection for a range of different system chemistries, initial supersaturations and residence times. The age of the sample during analysis is controlled by adjusting the flow rate. Faster rates allow for younger samples to be examined, but if flow is too fast not enough data are acquired to average out excess signal noise. Slower flow rates form older samples, but at very slow speeds particles settle and block flow, clogging the system. Proper background collection and subtraction is critical for data optimization. Overall, this MFR method is an ideal scheme for analyzing the in situ structures of phases that form during crystal growth in solution. As a proof of concept, high-resolution total X-ray scattering data of amorphous and crystalline calcium phosphates and amorphous calcium carbonate were collected for PDF analysis.

Single-wavelength X-ray anomalous diffraction (SAD) is a frequently employed technique to solve the phase problem in X-ray crystallography. The precision and accuracy of recovered anomalous differences are crucial for determining the correct phases. Continuous rotation (CR) and inverse-beam geometry (IBG) anomalous data collection methods have been performed on tetragonal lysozyme and monoclinic survivin crystals and analysis carried out of how correlated the pairs of Friedel's reflections are after scaling. A multivariate Bayesian model for estimating anomalous differences was tested, which takes into account the correlation between pairs of intensity observations and incorporates the a priori knowledge about the positivity of intensity. The CR and IBG data collection methods resulted in positive correlation between I(+) and I(−) observations, indicating that the anomalous difference dominates between these observations, rather than different levels of radiation damage. An alternative pairing method based on near simultaneously observed Bijvoet's pairs displayed lower correlation and it was unsuccessful for recovering useful anomalous differences when using the multivariate Bayesian model. In contrast, multivariate Bayesian treatment of Friedel's pairs improved the initial phasing of the two tested crystal systems and the two data collection methods.

Relativistic electron diffraction depends on linear and quadratic terms in the electric potential, the latter being neglected in the frequently used relativistically corrected Schrödinger equation. The quadratic electric potential term modifies atomic scattering amplitudes in particular for large-angle scattering and backscattering. The respective correction increases with increasing scattering angle, increasing atomic number and increasing kinetic energy. Conventional tabulations for electron scattering and its large-angle extrapolations can be amended in closed form by a universal correction based on the screened Coulomb potential squared.

A novel approach for finding and evaluating structural models of small metallic nanoparticles is presented. Rather than fitting a single model with many degrees of freedom, libraries of clusters from multiple structural motifs are built algorithmically and individually refined against experimental pair distribution functions. Each cluster fit is highly constrained. The approach, called cluster-mining, returns all candidate structure models that are consistent with the data as measured by a goodness of fit. It is highly automated, easy to use, and yields models that are more physically realistic and result in better agreement to the data than models based on cubic close-packed crystallographic cores, often reported in the literature for metallic nanoparticles.

The use of strongly bent crystals in spectrometers for pulses of a hard X-ray free-electron laser is explored theoretically. Diffraction is calculated in both dynamical and kinematical theories. It is shown that diffraction can be treated kinematically when the bending radius is small compared with the critical radius given by the ratio of the Bragg-case extinction length for the actual reflection to the Darwin width of this reflection. As a result, the spectral resolution is limited by the crystal thickness, rather than the extinction length, and can become better than the resolution of a planar dynamically diffracting crystal. As an example, it is demonstrated that spectra of the 12 keV pulses can be resolved in the 440 reflection from a 20 µm-thick diamond crystal bent to a radius of 10 cm.

The transformations from the primitive cells of the centered Bravais lattices to the corresponding centered cells have conventionally been listed as three-by-three matrices that transform three-space lattice vectors. Using those three-by-three matrices when working in the six-dimensional space of lattices represented as Selling scalars as used in Delone (Delaunay) reduction, one could transform to the three-space representation, apply the three-by-three matrices and then back-transform to the six-space representation, but it is much simpler to have the equivalent six-by-six matrices and apply them directly. The general form of the transformation from the three-space matrix to the corresponding matrix operating on Selling scalars (expressed in space S6) is derived, and the particular S6matrices for the centered Delone types are listed. (Note: in his later publications, Boris Delaunay used the Russian version of his surname, Delone.)

A crystallographic indexing algorithm, pinkIndexer, is presented for the analysis of snapshot diffraction patterns. It can be used in a variety of contexts including measurements made with a monochromatic radiation source, a polychromatic source or with radiation of very short wavelength. As such, the algorithm is particularly suited to automated data processing for two emerging measurement techniques for macromolecular structure determination: serial pink-beam X-ray crystallography and serial electron crystallography, which until now lacked reliable programs for analyzing many individual diffraction patterns from crystals of uncorrelated orientation. The algorithm requires approximate knowledge of the unit-cell parameters of the crystal, but not the wavelengths associated with each Bragg spot. The use of pinkIndexer is demonstrated by obtaining 1005 lattices from a published pink-beam serial crystallography data set that had previously yielded 140 indexed lattices. Additionally, in tests on experimental serial crystallography diffraction data recorded with quasi-monochromatic X-rays and with electrons the algorithm indexed more patterns than other programs tested.

X-ray emission under electron-channelling conditions is used to distinguish between a non-centrosymmetric half-Heusler and a centrosymmetric full-Heusler crystal. For TiCo1.5+xSn the space-group determination based on a Rietveld refinement procedure became challenging for increasing Co content (x > 0.2), while electron channelling proved successful for higher Co content (x = 0.35). This technique can be used on crystals as small as (10 nm)3.

Crystal structure identification of thin organic films entails a number of technical and methodological challenges. In particular, if molecular crystals are epitaxially grown on single-crystalline substrates a complex scenario of multiple preferred orientations of the adsorbate, several symmetry-related in-plane alignments and the occurrence of unknown polymorphs is frequently observed. In theory, the parameters of the reduced unit cell and its orientation can simply be obtained from the matrix of three linearly independent reciprocal-space vectors. However, if the sample exhibits unit cells in various orientations and/or with different lattice parameters, it is necessary to assign all experimentally obtained reflections to their associated individual origin. In the present work, an effective algorithm is described to accomplish this task in order to determine the unit-cell parameters of complex systems comprising different orientations and polymorphs. This method is applied to a polycrystalline thin film of the conjugated organic material 6,13-pentacene­quinone (PQ) epitaxially grown on an Ag(111) surface. All reciprocal vectors can be allocated to unit cells of the same lattice constants but grown in various orientations [sixfold rotational symmetry for the contact planes (102) and (102)]. The as-determined unit cell is identical to that reported in a previous study determined for a fibre-textured PQ film. Preliminary results further indicate that the algorithm is especially effective in analysing epitaxially grown crystallites not only for various orientations, but also if different polymorphs are present in the film.

Recent developments of two-color operation modes at X-ray free-electron laser facilities provide new research opportunities, such as X-ray pump/X-ray probe experiments and multiple-wavelength anomalous dispersion phasing methods. However, most existing indexing methods were developed for indexing diffraction data from monochromatic X-ray beams. Here, a new algorithm is presented for indexing two-color diffraction data, as an extension of the sparse-pattern indexing algorithm SPIND, which has been demonstrated to be capable of indexing diffraction patterns with as few as five peaks. The principle and implementation of the two-color indexing method, SPIND-TC, are reported in this paper. The algorithm was tested on both simulated and experimental data of protein crystals. The results show that the diffraction data can be accurately indexed in both cases. Source codes are publicly available at https://github.com/lixx11/SPIND-TC.

in Outlook Express and Thunderbird

Black holes sound wildly complicated. After all, there are all sorts of bizarre things going on: intense gravity, the warping of the fabric of space, the distortion of time itself. But when it comes to describing black holes, it comes down to just two numbers: the mass of the black hole and its spin. That’s right. Everything you physically need to describe a black hole is found in just these two numbers.

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Keeper Tracey Barnes talks about Billie Jean, an Andean bear, and her two new cubs at the Smithsonian's National Zoo.

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The post Device at the Smithsonian Environmental Research Center examines how phytoplankton would react if the ozone layer vanished appeared first on Smithsonian Insider.

The HSBC Climate Partnership (HCP) is a five-year partnership (2007-2011) between HSBC, The Smithsonian, The Climate Group, Earthwatch Institute and WWF to inspire action on climate change.
Working with these partners and engaging its employees around the world, HSBC hopes to tackle climate change impacts for people, forests, water, and cities. The HCP research of the Smithsonian's Center for Tropical Forest Science (CTFS) focuses on:
• Understanding the role of forests in the global carbon cycle
• Comparing temperate and tropical forests by establishing new plots in the temperate zone
• Quantifying the environmental services provided by tropical forests

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This new PBS Newshour video takes a look at a new exhibit at the Air and Space Museum celebrating NASA's space art program.

The post PBS Newshour takes a look at the new National Air and Space Museum exhibition “NASA | ART: 50 Years of Exploration” appeared first on Smithsonian Insider.

In 2010 Dr. Rachel Collin visited her colleagues at the Universidad Austral de Chile in Valdivia to collect some very special snails for her research at the Smithsonian Tropical Research Institute, Panama.

The post Smithsonian biologist Rachel Collin visits the Universidad Austral de Chile to collect special snails for her research. appeared first on Smithsonian Insider.

Mark Torchin, a marine ecologist at the Smithsonian Tropical Research Institute (STRI) in Panama, talks about how he studies the parasites of invasive marine animals such as snails. Much of his research focuses on biological invasions and the dynamics between the host, the parasites and the surrounding ecosystem.

The post Meet our Scientist–Mark Torchin tracks invasive marine species and their parasites in Panama appeared first on Smithsonian Insider.

On June 7 the Sun unleashed an spectacular solar flare with a substantial coronal mass ejection. A large cloud of plasma mushroomed up, and while some parts fell back into the Sun, most rushed off into space. The first two segments of this video are seen through the Atmospheric Imaging Assembly aboard NASA's Solar Dynamics Observatory. The AIA was developed by Smithsonian scientists.

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The post Salamanders: The Hidden Jewels of Appalachia appeared first on Smithsonian Insider.

Tom Crouch, Senior curator in the National Air and Space Museum's Aeronautics Division, discusses Thaddeus Lowe and the birth of American aerial reconnaissance during the Civil War. This presentation was recorded on May 11, 2011 on the National Mall.

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Meet Rachel Collin, a staff scientist and director of the Bocas Research Station at the Smithsonian Tropical Research Institute in Panama. Rachel studies the evolution of marine gastropods (snails) and oversees multiple disciplines of marine biology at the Collin Lab in Bocas del Toro.

The post Meet Our Scientist: Rachel Collin, an expert in the evolution and development of snails who is working in Panama appeared first on Smithsonian Insider.

It takes a Tlingit artist up to 2,000 hours, or 83 days, to weave just one ceremonial robe. Not surprisingly, this art form is practiced by a dedicated few including Tlingit artists Teri Rofkar and Shelly Laws of Alaska. In their presentation for the Smithsonian Spotlight series hosted by the Arctic Studies Center at the Anchorage Museum, Rofkar and Laws discuss the methods and cultural significance of robes, spruce root baskets and more.
For more information, go to http://www.mnh.si.edu/arctic/html/alaska.htm

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The post How do paleontologists identify dinosaur teeth? Smithsonian Curator Matthew Carrano identifies Cretaceous dinosaur teeth from the Washington D.C. area. appeared first on Smithsonian Insider.

The post The Space Shuttle Discovery, mounted atop a 747 jet, is delivered to the Smithsonian on April 17, 2012 appeared first on Smithsonian Insider.

The post Japanese acrobats ca. 1927, footage from the Smithsonian’s Human Studies Film Archive appeared first on Smithsonian Insider.

Speeding Up Science from Facebook Stories on Vimeo. In January 2011, Oregon State University ichthyologist Brian Sidlauskas led a research expedition into the little-known Cuyuni […]

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Meet Rachel Page, a Smithsonian scientist in Panama who studies frog-eating bats (fringe-lipped bats), among other topics. Her current research focuses on learning and memory in neotropical bats, combining field studies with laboratory experiments to learn about predator cognition and its effects on the evolution of their prey.

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Silent black & white archival film clip from "Japan: Promotional and Theatrical Footage, ca. 1927". The full film, which is 17 minutes long, includes segments from what are believed to be a theatrical film, a promotional film and, possibly, amateur film - all of unknown origin.

The post Geisha Hairstyling, ca. 1927, a silent black & white archival film clip from the Smithsonian’s Human Studies Film Archives appeared first on Smithsonian Insider.

The Smithsonian Science Education Center (formerly NSRC) was formed by the Smithsonian Institution and the National Academies in 1985 with the mission to improve the learning and teaching of science in school districts in the United States and throughout the world.

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Don your clean room clothing and take a glimpse into the Smithsonian's new Antarctic meteorite storage facility in Suitland, Md., where all of the Antarctic meteorites in the national collection are kept under tight security and tight airlocks.

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The post Indo-Pacific lionfish, an invasive species, invade the Atlantic appeared first on Smithsonian Insider.

One of Italy’s greatest treasures, Leonardo da Vinci’s Codex on the Flight of Birds, will be exhibited at the National Air and Space Museum from […]

The post da Vinci’s “Codex on the Flight of Birds” will be on view at Air and Space Museum, Sept. 13-Oct. 22. appeared first on Smithsonian Insider.

Bocas Research Station’s research assistant Arcadio Castillo ran into these curious looking fish babies while working close to the dock. After some investigation, we found […]

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Ever wonder why only male peacocks have such extravagant plumage? We ask caretaker Gwendolyn Cooper at Smithsonian’s National Zoo to explain.

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Get a look behind the scenes as we installed “Outside the Spacecraft: 50 Years of Extra-vehicular Activity,” a new exhibition on view at the Museum […]

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