Convolutional neural networks are useful for classifying grazing-incidence small-angle X-ray scattering patterns. They are also useful for classifying real experimental data.
X-ray reflectivity (XRR) is a powerful and popular scattering technique that can give valuable insight into the growth behavior of thin films. This study shows how a simple artificial neural network model can be used to determine the thickness, roughness and density of thin films of different organic semiconductors [diindenoperylene, copper(II) phthalocyanine and α-sexithiophene] on silica from their XRR data with millisecond computation time and with minimal user input or a priori knowledge. For a large experimental data set of 372 XRR curves, it is shown that a simple fully connected model can provide good results with a mean absolute percentage error of 8–18% when compared with the results obtained by a genetic least mean squares fit using the classical Parratt formalism. Furthermore, current drawbacks and prospects for improvement are discussed.
Over the past decade, ptychography has been proven to be a robust tool for non-destructive high-resolution quantitative electron, X-ray and optical microscopy. It allows for quantitative reconstruction of the specimen's transmissivity, as well as recovery of the illuminating wavefront. Additionally, various algorithms have been developed to account for systematic errors and improved convergence. With fast ptychographic microscopes and more advanced algorithms, both the complexity of the reconstruction task and the data volume increase significantly. PtychoShelves is a software package which combines high-level modularity for easy and fast changes to the data-processing pipeline, and high-performance computing on CPUs and GPUs.
Successes in animal health care presents many new challenges for veterinarians. Longer life spans in captivity mean zoo animals are now experiencing age-related health problems that their zoo predecessors never lived long enough to develop—like diabetes in cheetahs, arthritis in big cats and dental issues for coatis.
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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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BROOKINGS, S.D. — Julie DeJong can’t set foot on the ground of an Oregon marsh to gather duck eggs on a spring day in 1875. […]
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Any adventurer, hiker or backyard naturalist with a camera can help scientists survey and hopefully save the world’s amphibians thanks to a new social networking site that links “citizen scientists” with researchers tracking the decline of amphibians around the globe.
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Researchers from the Smithsonian Institution and the University of Florida have announced the discovery of a bone fragment, approximately 13,000 years old, in Florida with an incised image of a mammoth or mastodon.
The post Bone fragment is only Ice Age artwork from America to show a “proboscidean” appeared first on Smithsonian Insider.
Suzan Murray, chief veterinary medical officer at the Smithsonian’s National Zoological Park, recently returned from Hanoi, where she led a team of scientists training pathologists from Laos, Cambodia and Vietnam to better sample, recognize and detect wildlife diseases in hopes of preventing emerging pandemic disease.
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In fact, researchers have learned, the detached male pedipalps transfer more sperm faster after copulation is ended by the female rather than the male.
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Researchers at the Smithsonian Tropical Research Institute and University of Costa Rica studying why spiders do not stick to their own sticky webs have discovered that a spider's legs are protected by a covering of branching hairs and by a non-stick chemical coating. Their results are published online in the journal, Naturwissenschaften.
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Emmett Duffy, currently the Gluckman Professor of Marine Science at the College of William & Mary in Virginia, has been appointed director of the Smithsonian’s […]
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A one-cubic-foot approach to studying biodiversity as showcased in the new Biocube exhibit at the Smithsonian’s National Museum of Natural History has led to the […]
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Archan Chakraborty, Wei-Cheng Lin, Yu-Tsun Lin, Kuang-Jing Huang, Pei-Yu Wang, Yi-Feng Chang, Hsiang-Iu Wang, Kung-Ting Ma, Chun-Yen Wang, Xuan-Rong Huang, Yen-Hsien Lee, Bi-Chang Chen, Ya-Ju Hsieh, Kun-Yi Chien, Tzu-Yang Lin, Ji-Long Liu, Li-Ying Sung, Jau-Song Yu, Yu-Sun Chang, and Li-Mei Pai
Under metabolic stress, cellular components can assemble into distinct membraneless organelles for adaptation. One such example is cytidine 5'-triphosphate synthase (CTPS), which forms filamentous structures under glutamine deprivation. We have previously demonstrated that histidine (His)-mediated methylation regulates the formation of CTPS filaments to suppress enzymatic activity and preserve the CTPS protein under Gln deprivation, which promotes cancer cell growth after stress alleviation. However, it remains unclear where and how these enigmatic structures are assembled. Using CTPS-APEX2-mediated in vivo proximity labeling, we found that SNAP29 regulates the spatiotemporal filament assembly of CTPS along the cytokeratin network in a keratin 8 (KRT8)-dependent manner. Knockdown of synaptosome-associated protein 29 (SNAP29) interfered with assembly and relaxed the filament-induced suppression of CTPS enzymatic activity. Furthermore, APEX2 proximity labeling of keratin 18 (KRT18) revealed a spatiotemporal association of SNAP29 with cytokeratin in response to stress. Super-resolution imaging suggests that during CTPS filament formation, SNAP29 interacts with CTPS along the cytokeratin network. This study links the cytokeratin network to the regulation of metabolism by compartmentalization of metabolic enzymes during nutrient deprivation.
Bruce Campbell, of the Center for Earth and Planetary Studies at the Smithsonian's National Air and Space Museum, is at the National Radio Astronomy Observatory in Green Bank, W. Va., to make a radar map of the Moon.
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What does it take to care for a pride of lions? Go behind the scenes with Great Cats Curator Craig Saffoe as he works with animal keepers and veterinarians to prepare the National Zoo's frisky lion cubs for their public debut. For more about the Zoo's growing pride and to watch them on live webcams: http://nationalzoo.si.edu/Animals/GreatCats/default.cfm?cam=LC4
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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.
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This animation tells a Cheyenne story of how the Big Dipper came to be when a girl and her loyal brothers escape from a bison. […]
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Can a tendency to get distracted lead to a career in science? It did for paleoecologist Conrad Labandeira. Working on his family's farm, he would find himself falling into a study of insect life in the fields. "If you go after what interests you," he says, "the rest will always fall into place."
The post Smithsonian paleoecologist Conrad Labandeira talks about how he became a scientist and why he loves his work appeared first on Smithsonian Insider.
Going for the gut will soon become standard protocol for scientists working to unravel the complex living web of interactions between plants and animals on […]
The post Going for the gut: DNA from beetle stomachs reveals complex network appeared first on Smithsonian Insider.
The post Smithsonian scientists work to ensure survival of North America’s wild orchids appeared first on Smithsonian Insider.
A 57-acre research plot at a University of Michigan forest preserve northwest of Ann Arbor has been added to a Smithsonian Institution global network used […]
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Invasive species have become a problem in marine environments around the world, and the Chesapeake Bay and its tributaries are no exception. Non-native species of […]
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The crystal structure of triphenylmethanol, C19H16O, has been redetermined using data collected at 295 and 153 K, and is compared to the model published by Ferguson et al. over 25 years ago [Ferguson et al. (1992). Acta Cryst. C48, 1272–1275] and that published by Serrano-González et al., using neutron and X-ray diffraction data [Serrano-González et al. (1999). J. Phys. Chem. B, 103, 6215–6223]. As predicted by these authors, the hydroxy groups are involved in weak intermolecular hydrogen bonds in the crystal, forming tetrahedral tetramers based on the two independent molecules in the asymmetric unit, one of which is placed on the threefold symmetry axis of the Roverline{3} space group. However, the reliable determination of the hydroxy H-atom positions is difficult to achieve, for two reasons. Firstly, a positional disorder affects the full asymmetric unit, which is split over two sets of positions, with occupancy factors of ca 0.74 and 0.26. Secondly, all hydroxy H atoms are further disordered, either by symmetry, or through a positional disorder in the case of parts placed in general positions. We show that the correct description of the hydrogen-bonding scheme is possible only if diffraction data are collected at low temperature. The prochiral character of the hydrogen-bonded tetrameric supramolecular clusters leads to enantiomorphic three-dimensional graphs in each tetramer. The crystal is thus a racemic mixture of supS and supR motifs, consistent with the centrosymmetric nature of the Roverline{3} space group.
The compound poly[2-hydroxy-N-methylethan-1-aminium [μ3-cyanido-κ3C:C:N-di-μ-cyanido-κ4C:N-dicuprate(I)]], {(C3H10NO)[Cu2(CN)3]}n or [meoenH]Cu2(CN)3, crystallizes in the tetragonal space group P43. The structure consists of a three-dimensional (3D) anionic CuICN network with noncoordinated protonated N-methylethanolamine cations providing charge neutrality. Pairs of cuprophilic Cu atoms are bridged by the C atoms of μ3-cyanide ligands, which link these units into a 43 spiral along the c axis. The spirals are linked together into a 3D anionic network by the two other cyanide groups. The cationic moieties are linked into their own 43 spiral via N—H⋯O and O—H⋯O hydrogen bonds, and the cations interact with the 3D network via an unusual pair of N—H⋯N hydrogen bonds to one of the μ2-cyanide groups. Thermogravimetric analysis indicates an initial loss of the base cation and one cyanide as HCN at temperatures in the range 130–250 °C to form CuCN. We show how loss of a specific cyanide group from the 3D CuCN structure could form the linear CuCN structure. Further heating leaves a residue of elemental copper, isolated as the oxide.
Working in a lab is safe most of the time, “except when it isn’t, and that’s when being alone compounds the danger,” says a new lab safety video about working alone. You can watch it on YouTube or download it for offline viewing from the American Chemical Society’s Division of Chemical Health and Safety website. […]
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Supporters of the late educator and civil rights advocate Sal Castro are working to keep his Chicano Youth Leadership Conference alive.; Credit: Crystal Marie Lopez/Flickr
Adolfo Guzman-LopezWhen he died in 2013, Sal Castro drew praise as a Southern California civil rights leader who championed educational opportunities for generations of students of Mexican descent.
While a high school teacher in 1968, he helped thousands of students stage massive walkouts in Los Angeles' east side to protest high dropout rates and poor schooling that ignored their cultural background.
Supporters say his most influential legacy is the Chicano Youth Leadership Conference that he founded in 1963 as a weekend camp in the Santa Monica mountains. The gathering functioned as a cultural pep rally and intensive college application session.
“There was quite a large group of people that knew that this is not something that could die with him. That is when we had the idea to form a foundation to make sure that we keep his legacy alive,” said Myrna Brutti, the conference’s director.
Castro struggled to raise money for the conference, which counts among its alumni such well-known leaders as former Los Angeles Mayor Antonio Villaraigosa and filmmaker Moctesuma Esparza.
The Sal Castro Foundation typically spends about $60,000 to pay for the camp, including food and bus transportation. The group raises the money so that students can attend for free.
Applications to the next conference on March 6 have been sent to LAUSD high school campuses, targeting low-income Latinos, with a Feb. 20 deadline. Organizers hope in years ahead to open the conference to other Southland schools.
Brutti, a middle school principal, said she sees many more college application and high school to college bridge programs today. But a large group of high school students still go without college counseling, she said.
“These are 4.0, 3.7, 3.9, 4.2 [grade-point average] students that graduate from high school and go directly into the workforce because no one has taken the time to really go in depth on…what is available to them,” Brutti said.
The conference gives students like high school junior Savannah Pierce a broader view of their post-graduation choices. She attended the conference in October.
“I never really gave much thought to getting a doctorate degree,” Pierce said. “I thought I was going to do my four years of undergraduate and maybe graduate school. I never realized how many options and opportunities there were.”
When Castro talked to students of Mexican descent, he often transitioned seamlessly between English and Spanish, giving brief lessons on Mexican history and notable Mexicans. The current conference leaders are keeping that tradition alive.
“I never realized how deep and important my culture is and how rich it is with knowledge, and how hard people have worked in the past to get me where I am today,” Pierce said.
Other resources for students seeking help with college applications include:
1. California college and career planning
2. The College Board’s college planning helper
3. The Princeton Review’s college helper
This content is from Southern California Public Radio. View the original story at SCPR.org.