6,999 research outputs found

    The 43GHz SiO maser in the circumstellar envelope of the AGB star R Cassiopeiae

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    We present multi-epoch, total intensity, high-resolution images of 43GHz, v=1, J=1-0 SiO maser emission toward the Mira variable R Cas. In total we have 23 epochs of data for R Cas at approximate monthly intervals over an optical pulsation phase range from 0.158 to 1.78. These maps show a ring-like distribution of the maser features in a shell, which is assumed to be centred on the star at a radius of 1.6 to 2.3 times the stellar radii. It is clear from these images that the maser emission is significantly extended around the star. At some epochs a faint outer arc can be seen at 2.2 stellar radii. The intensity of the emission waxes and wanes during the stellar phase. Some maser features are seen infalling as well as outflowing. We have made initial comparisons of our data with models by Gray et. al. (2009).Comment: 12 pages, 14 figure

    BAL and non-BAL quasars: Continuum, emission, and absorption properties establish a common parent sample

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    Using a sample of \simeq144,000 quasars from the Sloan Digital Sky Survey data release 14 we investigate the outflow properties, evident both in absorption and emission, of high-ionization Broad Absorption Line (BAL) and non-BAL quasars with redshifts 1.6 z\lesssim z \leq 3.5 and luminosities 45.3 <log10(Lbol)<< \log_{10}(L_{bol}) < 48.2 erg s1^{-1}. Key to the investigation is a continuum and emission-line reconstruction scheme, based on mean-field independent component analysis, that allows the kinematic properties of the CIVλ\lambda1550 emission line to be compared directly for both non-BAL and BAL quasars. CIV-emission blueshift and equivalent-width (EW) measurements are thus available for both populations. Comparisons of the emission-line and BAL-trough properties reveal strong systematic correlations between the emission and absorption properties. The dependence of quantitative outflow indicators on physical properties such as quasar luminosity and luminosity relative to Eddington-luminosity are also shown to be essentially identical for the BAL and non-BAL populations. There is an absence of BALs in quasars with the hardest spectral energy distributions (SEDs), revealed by the presence of strong HeIIλ\lambda1640 emission, large CIVλ\lambda1550-emission EW and no measurable blueshift. In the remainder of the CIV-emission blueshift versus EW space, BAL and non-BAL quasars are present at all locations; for every BAL-quasar it is possible to identify non-BAL quasars with the same emission-line outflow properties and SED-hardness. The co-location of BAL and non-BAL quasars as a function of emission-line outflow and physical properties is the key result of our investigation, demonstrating that (high-ionization) BALs and non-BALs represent different views of the same underlying quasar population

    Characterizing Quasar C iv Emission-line Measurements from Time-resolved Spectroscopy

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    We use multi-epoch quasar spectroscopy to determine how accurately single-epoch spectroscopy can locate quasars in emission-line parameter space in order to inform investigations where time-resolved spectroscopy is not available. We explore the improvements in emission-line characterization that result from using non-parametric information from many lines as opposed to a small number of parameters for a single line, utilizing reconstructions based on an independent component analysis applied to the data from the Sloan Digital Sky Survey Reverberation Mapping project. We find that most of the quasars are well described by just two components, while more components signal a quasar likely to yield a successful reverberation mapping analysis. In single-epoch spectroscopy the apparent variability of equivalent width is exaggerated because it is dependent on the continuum. Multi-epoch spectroscopy reveals that single-epoch results do not significantly change where quasars are located in CIV parameter space and do not have a significant impact on investigations of the global Baldwin Effect. Quasars with emission line properties indicative of higher L/LEddL/L_{Edd} are less variable, consistent with models with enhanced accretion disk density. Narrow absorption features at the systemic redshift may be indicative of orientation (including radio-quiet quasars) and may appear in as much as 20% of the quasar sample. Future work applying these techniques to lower luminosity quasars will be important for understanding the nature of accretion disk winds

    Functional and clinical studies reveal pathophysiological complexity of CLCN4-related neurodevelopmental condition

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    Missense and truncating variants in the X-chromosome-linked CLCN4 gene, resulting in reduced or complete loss-of-function (LOF) of the encoded chloride/proton exchanger ClC-4, were recently demonstrated to cause a neurocognitive phenotype in both males and females. Through international clinical matchmaking and interrogation of public variant databases we assembled a database of 90 rare CLCN4 missense variants in 90 families: 41 unique and 18 recurrent variants in 49 families. For 43 families, including 22 males and 33 females, we collated detailed clinical and segregation data. To confirm causality of variants and to obtain insight into disease mechanisms, we investigated the effect on electrophysiological properties of 59 of the variants in Xenopus oocytes using extended voltage and pH ranges. Detailed analyses revealed new pathophysiological mechanisms: 25% (15/59) of variants demonstrated LOF, characterized by a shift of the voltage-dependent activation to more positive voltages, and nine variants resulted in a toxic gain-of-function, associated with a disrupted gate allowing inward transport at negative voltages. Functional results were not always in line with in silico pathogenicity scores, highlighting the complexity of pathogenicity assessment for accurate genetic counselling. The complex neurocognitive and psychiatric manifestations of this condition, and hitherto under-recognized impacts on growth, gastrointestinal function, and motor control are discussed. Including published cases, we summarize features in 122 individuals from 67 families with CLCN4-related neurodevelopmental condition and suggest future research directions with the aim of improving the integrated care for individuals with this diagnosis

    Boundaries of the Construct of Unemployment in the Pre-Retirement Years: Exploring an Expanded Measurement of Lost-Work Opportunity

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    There is uncertainty related to whether retirement negatively affects health—possibly due to complexity around retirement decisions. Lost-work opportunity through unemployment or forced retirement has been shown to negatively affect health. Lost-work opportunity can be captured in two measurement fields, either a reported experience of being forced into retirement or reported unemployment. However, 17% of individuals retiring due to the loss of work opportunity identified in qualitative interviewing (i.e., unemployment, temporary lay-offs, company buy-outs, forced relocations, etc.) do not report this unemployment or involuntary retirement in quantitative survey responses. We propose broadening the conceptualization of late-career unemployment to incorporate other lost work opportunity scenarios. Using the Health and Retirement Study (HRS), a lost-work opportunity score (LOS) was computed from items indicating unemployment and forced or unplanned retirement. Correlations were computed between this LOS and all continuous variables in the RAND longitudinal compilation of the HRS to determine its convergent and discriminant validity. The LOS demonstrated a Chronbach’s alpha of α = .82 and had convergent validity with constructs of employment (9 variables), finances (36 variables), and health (14 variables), as predicted by the literature on retirement timing. No other continuous variables in the HRS were identified with a moderate or strong correlation to LOS, demonstrating discriminant validity. Further research should explore whether a combination of variables in the HRS can improve the accuracy of measuring lost-work opportunity. Improved precision in measurement, through an expanded conceptualization of lost-work opportunity, may help explicate the retirement-related factors that affect health, to inform policy and support healthy aging decisions at a societal level

    Tacit rejection of policy and teacher ambivalence – insights into English language teaching in Bahrain through actors’ perceptions

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    This article develops Phillips and Ochs's (2003) framework for policy borrowing, particularly their theorisations about indigenisation of international programmes. It uses the example of communicative language teaching (CLT) in Bahrain, exploring teacher perspectives regarding the effects of CLT on the preexisting arrangements in the national education system and the impact of contextual factors on the potential for CLT implementation. The author conducted qualitative focus groups with English language teachers in 10 schools. The analysis elucidates how teachers were tailoring their own ways through the new reforms to strike a satisfactory balance between the government's aims and the attitudes of the public. It answers the question, "What happens to English language teaching policy when it is transplanted to a different culture?" and concludes that it becomes actively rejected. The conclusion offers a conceptual development of Phillips and Ochs's framework, adding the option of rejection to the indigenisation stage. The article ends with some practical implications

    Multi-Disciplinary Project-Based Paradigm That Uses Hands-On Desktop Learning Modules and modern Learning Pedagogies

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    It has been established that traditional lectures ARE NOT best for student learning – yet that is what the community almost universally does! Furthermore, engineers work in broad multidisciplinary teams while classroom learning is individual and narrow. Yet, educators rarely invest the time and resources necessary to employ such innovations. In this CCLI type II award we are further refining Desktop Learning Modules (DLMs) within a Cooperative, Hands-on, Active, Problem based, Learning (CHAPL) setting for Chemical, Civil, Mechanical, Bio- and Electrical Engineering courses at a diverse set of institutions, including a community college engaged through a distance learning mode. A workbook is being developed and tested for easier adoption of the hands-on units and accompanying pedagogy. Existing concept inventories are not always showing significant gains in apparent student learning either for control or experimental groups and we are concluding these assessments are not well aligned with the macroscale design calculations being emphasized in the course. Therefore, new concept question assessments are being developed consisting of some macroscale questions from past inventories along with conceptual essay and calculation based questions aligned more specifically with the DLM processes at hand. Past implementations like this show students learn key concepts at least as well from each other in a guided inquiry as they do from lecture. Also, a mixed qualitative / quantitative assessment using a critical reasoning rubric reveals student abilities become better aligned with what is expected of graduating engineers ready for industry and that the CHAPL/DLM environment serves to reinforce understanding of physical phenomena, and to develop analytical and evaluative problem-solving skills. Interviews, surveys and team reports reveal students are better able to visualize concepts and that classroom exercises are promoting team skills and academic rigor. Faculty interviews reveal enhanced awareness of student misconceptions and improved monitoring of student growth in conceptual understanding and interpersonal skills. The poster and paper will highlight our findings and illustrate the CHAPL environment. Hands-on DLMs with cartridges used in teaching principles in the various disciplines will be demonstrated. A survey will be offered to those viewing the poster to assess potential interest in adoption of the DLMs and in participating in a follow-on NSF Type III proposal for Transforming Undergraduate Engineering Education through use of the DLMs and associated CHAPL pedagogies

    Mitochondrial DNA signals of late glacial recolonization of Europe from near Eastern refugia

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    Human populations, along with those of many other species, are thought to have contracted into a number of refuge areas at the height of the last Ice Age. European populations are believed to be, to a large extent, the descendants of the inhabitants of these refugia, and some extant mtDNA lineages can be traced to refugia in Franco-Cantabria (haplogroups H1, H3, V, and U5b1), the Italian Peninsula (U5b3), and the East European Plain (U4 and U5a). Parts of the Near East, such as the Levant, were also continuously inhabited throughout the Last Glacial Maximum, but unlike western and eastern Europe, no archaeological or genetic evidence for Late Glacial expansions into Europe from the Near East has hitherto been discovered. Here we report, on the basis of an enlarged whole-genome mitochondrial database, that a substantial, perhaps predominant, signal from mitochondrial haplogroups J and T, previously thought to have spread primarily from the Near East into Europe with the Neolithic population, may in fact reflect dispersals during the Late Glacial period, ?19–12 thousand years (ka) ago.<br/
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