3,949 research outputs found

    Preparing Tomorrow’s World Language Teacher Today: The Case for Seamless Induction

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    This essay is a call to action. It offers a comprehensive overview of the challenges facing world language (WL) teacher educators and their employers, the K-12 schools, during the teacher induction period. We propose a new paradigm for WL teacher education based on national accreditation standards, best-practice pedagogy, insights from the professional literature on methods education, and the enhanced role of the methods instructor/supervisor. In order to become successful in the classroom, the pre-service educator undergoes a seamless period of induction that is student-centered and college/university-supported beyond the classroom arena

    The Color of COVID-19: Structural Racism and the Pandemic’s Disproportionate Impact on Older Racial and Ethnic Minorities

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    Objectives: The aim of this evidence-based theoretically informed essay is to provide an overview of how and why the COVID-19 outbreak is particularly detrimental for the health of older Black and Latinx adults. Methods: We draw upon current events, academic literature, and numerous data sources to illustrate how biopsychosocial factors place older adults at higher risk for COVID-19 relative to younger adults, and how structural racism magnifies these risks for older Black and Latinx adults. Results: We identify three proximate mechanisms through which structural racism operates as a fundamental cause of racial/ethnic inequalities in COVID-19 burden among older adults: (1) Risk of exposure; (2) Weathering processes; and (3) Health care access and quality. Discussion: While the ongoing COVID-19 pandemic is an unprecedented crisis, the racial/ethnic health inequalities among older adults it has exposed are long-standing and deeply rooted in structural racism within American society. This knowledge presents both challenges and opportunities for researchers and policymakers as they seek to address the needs of older adults. It is imperative that federal, state, and local governments collect and release comprehensive data on the number of confirmed COVID-19 cases and deaths by race/ethnicity and age to better gauge the impact of outbreak across minority communities. We conclude with a discussion of incremental steps to be taken to lessen the disproportionate burden of COVID-19 among older Black and Latinx adults, as well as the need for transformative actions that address structural racism in order to achieve population health equity

    The symbiotic binary system RX Puppis: a possible recurrent nova with a Mira companion

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    We present an analysis of photometric and spectroscopic observations of the symbiotic binary system RX Pup with the aims of developing a reliable binary for the system and identifying mechanisms responsible for its spectacular activity. The binary is composed of a long-perod Mira variable surrounded by a thick dust shell and a hot white dwarf companion. The hot component produces practically all activity observed in the UV, optical and radio range, while variable obscuration of the Mira by circumstellar dust is responsible for long-term changes in the near-IR magnitudes. The observations show RX Pup underwent a nova-like eruption during the last three decades. The hot component contracted in radius at roughly constant luminosity from 1975 to 1986, and was the source of a strong stellar wind which prevented it from accreting material lost in the Mira wind. Around 1988/9 the hot component turned over in the HR diagram and by 1991 its luminosity had faded by a factor of about 30 with respect to the maximum plateau value and the hot wind had practically ceased. By 1995 the nova remnant started to accrete material from the Mira wind, as indicated by a general increase in intensity of the optical continuum and HI emission. The quiescent spectrum resembles the quiescent spectra of symbiotic recurrent novae, and its intensity indicates the hot component must accrete as much as about 1 per cent of the Mira wind, which is more or less the amount predicted by Bondi-Hoyle theory. The earliest observational records from the 1890s suggest that another nova-like eruption of RX Pup occurred around 1894.Comment: 23 pages, 12 figues, MNRAS - accepte

    GTMDs and the factorization of exclusive double Drell-Yan

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    Different exclusive processes have been proposed to access the generalized transverse momentum dependent distributions (GTMDs) with no proof of factorization, which allows to rigorously define the GTMDs. Using Soft Collinear Effective Theory we derive for the first time the factorization of the differential cross section for the exclusive double Drell-Yan process for the exclusive double Drell-Yan process pion N to N' gamma* gamma* to N' (l^+l^-)(l^+l^-), for small transverse momenta of the photons in terms of a perturbatively calculable hard factor, GTMDs and light-cone wave functions (LCWFs). We find that the hard factor of the process can be obtained from single inclusive Drell-Yan production so that one can resum logarithms at high orders in QCD. We also discuss the evolution of the GTMDs and the LCWFs.Comment: 9 pages, 3 figure. Version accepted for publicatio

    Spinodal decomposition of Fe-Cu nanocrystals: Control of atomic-magnetic-moment and magnetic properties

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    Experimental results corresponding to the saturation magnetization and coercive field during the decomposition, upon annealing, of bcc and fcc Fe_xCu_(1-x), obtained by mechanical alloying are reported. The overall behavior points out that the decomposition takes place in two steps: (i) at low temperatures a decrease of the saturation magnetic moment as well as an anomalous thermal dependence of coercive field are observed, however, no phase transformation is detected, and (ii) for further annealing temperatures a new phase appears; the magnetization tends to increase and the coercive field abruptly increases. The analysis of the results leads us to conclude that the first step corresponds to a spinodal decomposition. Fluctuations in the local composition give rise to coexistence of adjacent regions with Curie temperature varying continuously in a range of 1000 K across distances of a few nanometers, thus allowing the tailoring of the magnetic nanostructures

    Non-invasive Diabetes Detection using Gabor Filter: A Comparative Analysis of Different Cameras

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    This paper compares and explores the performance of both mobile device camera and laptop camera as convenient tool for capturing images for non-invasive detection of Diabetes Mellitus (DM) using facial block texture features. Participants within age bracket 20 to 79 years old were chosen for the dataset. 12mp and 7mp mobile cameras, and a laptop camera were used to take the photo under normal lighting condition. Extracted facial blocks were classified using k-Nearest Neighbors (k-NN) and Support Vector Machine (SVM). 100 images were captured, preprocessed, filtered using Gabor, and iterated. Performance of the system was measured in terms of accuracy, specificity, and sensitivity. Best performance of 96.7% accuracy, 100% sensitivity, and 93% specificity were achieved from 12mp back camera using SVM with 100 images.Comment: 11 pages, 5 figures, 3 tables, conferenc

    Tomato Spotted Wilt Virus NSs Protein Supports Infection and Systemic Movement of a Potyvirus and Is a Symptom Determinant

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    Plant viruses are inducers and targets of antiviral RNA silencing. To condition susceptibility, most plant viruses encode silencing suppressor proteins that interfere with antiviral RNA silencing. The NSs protein is an RNA silencing suppressor in orthotospoviruses, such as the tomato spotted wilt virus (TSWV). The mechanism of RNA silencing suppression by NSs and its role in virus infection and movement are poorly understood. Here, we cloned and tagged TSWV NSs and expressed it from a GFP-tagged turnip mosaic virus (TuMV-GFP) carrying either a wild-type or suppressor-deficient (AS9) helper component proteinase (HC-Pro). When expressed in cis, NSs restored pathogenicity and promoted systemic infection of suppressor-deficient TuMV-AS9-GFP in Nicotiana benthamiana and Arabidopsis thaliana. Inactivating mutations were introduced in NSs RNA-binding domain one. A genetic analysis with active and suppressor-deficient NSs, in combination with wild-type and mutant plants lacking essential components of the RNA silencing machinery, showed that the NSs insert is stable when expressed from a potyvirus. NSs can functionally replace potyviral HC-Pro, condition virus susceptibility, and promote systemic infection and symptom development by suppressing antiviral RNA silencing through a mechanism that partially overlaps that of potyviral HC-Pro. The results presented provide new insight into the mechanism of silencing suppression by NSs and its effect on virus infection

    Mechanically driven alloying of immiscible elements (Comment)

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    In conclusion we have proven that the fact that both fcc FeCu and bcc Fe magnetization agree at 300 K is simply an accident and our data at low temperature show clearly that the Fe contribution after precipitation from the metastable phase has a deficiency in magnetization of at least 20% with respect to the Fe state in fcc FeCu metastable solid solution

    The Apollo Lunar Sample Image Collection: Digital Archiving and Online Access

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    The primary goal of the Apollo Program was to land human beings on the Moon and bring them safely back to Earth. This goal was achieved during six missions - Apollo 11, 12, 14, 15, 16, and 17 - that took place between 1969 and 1972. Among the many noteworthy engineering and scientific accomplishments of these missions, perhaps the most important in terms of scientific impact was the return of 382 kg (842 lb.) of lunar rocks, core samples, pebbles, sand, and dust from the lunar surface to Earth. Returned samples were curated at JSC (then known as the Manned Spacecraft Center) and, as part of the original processing, high-quality photographs were taken of each sample. The top, bottom, and sides of each rock sample were photographed, along with 16 stereo image pairs taken at 45-degree intervals. Photographs were also taken whenever a sample was subdivided and when thin sections were made. This collection of lunar sample images consists of roughly 36,000 photographs; all six Apollo missions are represented

    Tailoring Upconversion and Morphology of Yb/Eu Doped Y2O3 Nanostructures by Acid Composition Mediation

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    The authors also acknowledge funding from the European Commission through the projects 1D-NEON (H2020-NMP-2015, grant 685758-21D). The work was also partially funded by the Nanomark collaborative project between INCM (Imprensa Nacional-Casa da Moeda) and CENIMAT/i3N. P.A. Carvalho acknowledges support from the Research Council of Norway through grants 275752 and 197405/F50.The present study reports the production of upconverter nanostructures composed by a yttrium oxide host matrix co-doped with ytterbium and europium, i.e., Y2O3:Yb3+/Eu3+. These nanostructures were formed through the dissociation of yttrium, ytterbium and europium oxides using acetic, hydrochloric and nitric acids, followed by a fast hydrothermal method assisted by microwave irradiation and subsequent calcination process. Structural characterization has been carried out by X-ray diffraction (XRD), scanning transmission electron microscopy (STEM) and scanning electron microscopy (SEM) both coupled with energy dispersive X-ray spectroscopy (EDS). The acid used for dissociation of the primary oxides played a crucial role on the morphology of the nanostructures. The acetic-based nanostructures resulted in nanosheets in the micrometer range, with thickness of around 50 nm, while hydrochloric and nitric resulted in sphere-shaped nanostructures. The produced nanostructures revealed a homogeneous distribution of the doping elements. The thermal behaviour of the materials has been investigated with in situ X-Ray diffraction and differential scanning calorimetry (DSC) experiments. Moreover, the optical band gaps of all materials were determined from diffuse reflectance spectroscopy, and their photoluminescence behaviour has been accessed showing significant differences depending on the acid used, which can directly influence their upconversion performance.publishersversionpublishe
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