Impact of extreme electrical fields on charge density distributions in Al3Sc alloy

Indexación: Web of Science.In this study, the authors investigated how extreme electrical fields affect charge distribution of metallic surfaces and bond character at the moment of evaporation. The surface structure and neighborhood chemistry were also studied as a function of various field evaporation pathways. Density functional theory (DFT) was used to model the surface bonding and charge distribution and then correlate the DFT results with experimental results by comparing the calculated evaporation fields with atom probe tomography measurements. The evaporation fields of different surface neighborhood chemistries in L1(2)-Al3Sc were calculated, with the Sc atoms occupying the corners of a cubic unit cell and the Al atoms occupying the face centers. Al-Al surface atoms are found via DFT to be more likely to evaporate as dimers because of the Al-Al shared charge density. In contrast, Al-Sc evaporates as single ions due to the increased density localized around the Sc atom. This difference in evaporation behavior correlates with the resistance to degradation under extreme fields. This work allows better interpretation of the atom probe data by clarifying the relationship between different evaporation events and the role of surface and subsurface chemistry. (C) 2016 Author(s).http://avs.scitation.org/doi/10.1116/1.496483

Modeling field evaporation degradation of metallic surfaces by first principles calculations: A case study for Al, Au, Ag, and Pd

Indexación: Scopus.Under the effects of an extreme electric field, the atoms on a metallic surface evaporate by breaking their bonds with the surface. In this work, we present the effects of a high electric field, by the use of computational simulations, for different metallic surface chemistries: Al, Au, Ag, and Pd. To model this bond breaking procedrure (i.e. field evaporation), we use density functional theory through the Quantum-Espresso (QE) simulation package, which incorporates the electric fields by adding a saw-like funcion into the Hamiltonian. This approach, known as dipole correction, was applied to all simulations as is implemented in the QE package. In this work, we calculate the evaporation field (Fe ) for all metallic species, which corresponds to the mean field at which atoms can break their bonds from the surface and evaporate. This result is compared with experimantal data from Atom Probe Tomography (APT) and computational data from prior simulations. © Published under licence by IOP Publishing Ltd.This work was supported by the Proyecto FONDECYT Iniciación 11130501. JP Also acknowledges partial support from Proyecto FONDECYT Regular 1140514 and Proyecto UAB-775. CL acknowledges support from Proyecto FONDECYT Iniciación 11150279, Proyecto PAI-79140025, and Proyecto DI-1350-16/R.https://iopscience.iop.org/article/10.1088/1742-6596/1043/1/01203

Identification of methotrexate as a heterochromatin-promoting drug.

Heterochromatin is a tightly packed form of DNA involved in gene silencing, chromosome segregation, and protection of genome stability. Heterochromatin is becoming more recognized in tumor suppression and may thus serve as a potential target for cancer therapy. However, to date there are no drugs that are well established to specifically promote heterochromatin formation. Here, we describe a screening method using Drosophila to identify small molecule compounds that promote heterochromatin formation, with the purpose of developing epigenetic cancer therapeutics. We took advantage of a Drosophila strain with a variegated eye color phenotype that is sensitive to heterochromatin levels, and screened a library of 97 FDA approved oncology drugs. This screen identified methotrexate as the most potent small molecule drug, among the 97 oncology drugs screened, in promoting heterochromatin formation. Interestingly, methotrexate has been identified as a JAK/STAT inhibitor in a functional screen, causing reduced phosphorylation of STAT proteins. These findings are in line with our previous observation that unphosphorylated STAT (uSTAT) promotes heterochromatin formation in both Drosophila and human cells and suppresses tumor growth in mouse xenografts. Thus, Drosophila with variegated eye color phenotypes could be an effective tool for screening heterochromatin-promoting compounds that could be candidates as cancer therapeutics

Global priorities for conservation across multiple dimensions of mammalian diversity

Conservation priorities that are based on species distribution, endemism, and vulnerability may underrepresent biologically unique species as well as their functional roles and evolutionary histories. To ensure that priorities are biologically comprehensive, multiple dimensions of diversity must be considered. Further, understanding how the different dimensions relate to one another spatially is important for conservation prioritization, but the relationship remains poorly understood. Here, we use spatial conservation planning to (i) identify and compare priority regions for global mammal conservation across three key dimensions of biodiversity-taxonomic, phylogenetic, and traits-and (ii) determine the overlap of these regions with the locations of threatened species and existing protected areas. We show that priority areas for mammal conservation exhibit low overlap across the three dimensions, highlighting the need for an integrative approach for biodiversity conservation. Additionally, currently protected areas poorly represent the three dimensions of mammalian biodiversity. We identify areas of high conservation priority among and across the dimensions that should receive special attention for expanding the global protected area network. These high-priority areas, combined with areas of high priority for other taxonomic groups and with social, economic, and political considerations, provide a biological foundation for future conservation planning efforts

Telemedicine Volunteering Experience as a Medical Student During the COVID-19 Pandemic in Brazil

The coronavirus disease 2019 (COVID-19) pandemic has strongly affected Brazil and many universities canceled in-person classes for an indefinite period. Many Brazilian medical students enrolled themselves as volunteers in telemedicine services across the country. This text will share the authors’ experience in telemedicine and their insights into the topic as volunteer medical students in Brazil

Experiências profissionais na escola e os sentidos da educação Física

Este estudo tem como objetivo compreender de que maneira as experiências profissionais singularizam a disciplina Educação Física no contexto escolar. A pesquisa foi desenvolvida em uma escola do município de Vitória-ES e focou os espaços de interação nos quais ocorria um maior número de experiências produzidas pelos sujeitos profissionais. A aproximação com o problema e as interpretações fundamentaram-se na teoria da ação. Opta por uma metodologia de abordagem qualitativa, pelo estudo etnográfico e pela observação participante. Para tanto, utiliza, como instrumento de coleta de dados os diálogos estabelecidos com os profissionais, a observação de espaços-tempos de interação, a análise dos documentos produzidos pela escola. Os sujeitos da pesquisa foram: a diretora, as pedagogas, as professoras regentes e as professoras de Educação Física. Como resultado, identifica quatro categorias fundamentais. A Educação Física aparece como curinga, disciplina menor, centro das festividades e lugar de acirrada tensão entre profissionalização e desprofissionalização. A legitimidade da Educação Física na instituição advém não do reconhecimento de seus conteúdos, mas do potencial de suporte às demais disciplinas, seus conteúdos e organização institucional. As representações construídas em torno da Educação Física nessa escola não podem ser abstraídas do seu reconhecimento específico, fato que às veses parece passar despercebido pelos profissionais. Nesse jogo conflituoso, a Educação Física é significada ora de forma a ser valorizada, ora a ser desvalorizada. A desvalorização tende a perpassar o universo da escola enquanto que um certo significado de valorização da disciplina ocorreu em alguns momentos pontuais e , às vezes, frágeis

Neural network interpolation of the magnetic field for the LISA Pathfinder Diagnostics Subsystem

LISA Pathfinder is a science and technology demonstrator of the European Space Agency within the framework of its LISA mission, which aims to be the first space-borne gravitational wave observatory. The payload of LISA Pathfinder is the so-called LISA Technology Package, which is designed to measure relative accelerations between two test masses in nominal free fall. Its disturbances are monitored and dealt by the diagnostics subsystem. This subsystem consists of several modules, and one of these is the magnetic diagnostics system, which includes a set of four tri-axial fluxgate magnetometers, intended to measure with high precision the magnetic field at the positions of the test masses. However, since the magnetometers are located far from the positions of the test masses, the magnetic field at their positions must be interpolated. It has been recently shown that because there are not enough magnetic channels, classical interpolation methods fail to derive reliable measurements at the positions of the test masses, while neural network interpolation can provide the required measurements at the desired accuracy. In this paper we expand these studies and we assess the reliability and robustness of the neural network interpolation scheme for variations of the locations and possible offsets of the magnetometers, as well as for changes in environmental conditions. We find that neural networks are robust enough to derive accurate measurements of the magnetic field at the positions of the test masses in most circumstances

Round trunk squash : two new varieties

El objetivo de este trabajo fue mejorar la calidad de fruto maduro en el zapallito redondo del tronco [Cucurbita máxima Duch., variedad zapallito (Carriére) Millán], para aprovecharlo con doble propósito y no solamente como hortaliza para relleno. Para ello debían eliminarse caracteres indeseables : falta de uniformidad; escasa proporción de pulpa; pérdida de sabor y aspecto; aparición de rugosidades , verrugas, turbantes pronunciados y, especialmente, cáscara blanda a la madurez, que lo hace susceptible a enfer-medades. El material fitogenético fue elegido de una colección con más de quinientas líneas homocigotas, arbustoides y plagiótropas, formada por las progenies de cruzamientos entre el Zapallito (Carriére) Millán por la variedad Typica y por la variedad Zipinka. Se obtuvieron así dos nuevos cultivares de crecimiento arbustoide, buena cobertura; frutos de cáscara verde, dura, lisa y limpia; mejor proporción y calidad de pul-pa (textura, color y tenor azucarino), denominadas YANQUE FCA y YANTA FCA.The main objective of this study was to improve the quality of the mature fruit of the round trunk squash [Cucurbita máxima Duch., vr zapallito (Carriére) Millán], so that it could be used as a double purpose squash and not only for stuffing when green. Whit that aim in view, it was necessary to eliminate undesirable characteristics such as : lack of uniformity, low proportion of pulp, loss of flavor an do good aspect, presen ce of roughnesses, warts, marked “turbans"and, especially, soft skin at maturity, which made it very susceptible to disease. The phytogenetic material used to begin this development was obteined from a collection of over 500 homozygous, shruby, and plagiotropous lines, made up by the progenies of the crossing between Zapallito (Carriére)Millán with Var. Typica and Var. Zipinka. As a result, we have developed two new lines of squash of shruby growth, good cover, skin that is green, hard, smooth and clean, and better proportion and quality of pulp (in texture, color, and sugar content), named YANQUE FCA and YANTA FCAFil: Bartucciotto, C. V.. Universidad Nacional de Cuyo. Facultad de Ciencias Agrarias. Departamento de Producción AgropecuariaFil: Ormeño, A. . Universidad Nacional de Cuyo. Facultad de Ciencias Agrarias. Departamento de Producción AgropecuariaFil: Marianetti, A.. Universidad Nacional de Cuyo. Facultad de Ciencias Agrarias. Departamento de Producción AgropecuariaFil: Niveyro, L. . Universidad Nacional de Cuyo. Facultad de Ciencias Agrarias. Departamento de Producción AgropecuariaFil: Loyola, A. P. . Universidad Nacional de Cuyo. Facultad de Ciencias Agrarias. Departamento de Producción AgropecuariaFil: Arenas, A. . Universidad Nacional de Cuyo. Facultad de Ciencias Agrarias. Departamento de Producción Agropecuari