7,265 research outputs found
The 43GHz SiO maser in the circumstellar envelope of the AGB star R Cassiopeiae
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
Using a sample of 144,000 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 3.5 and luminosities 45.3
48.2 erg s. 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
CIV1550 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
HeII1640 emission, large CIV1550-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
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 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
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
Bringing women into the spotlight: the impact of preoperative anemia in gynecological surgery
Boundaries of the Construct of Unemployment in the Pre-Retirement Years: Exploring an Expanded Measurement of Lost-Work Opportunity
There is uncertainty related to whether retirement negatively affects healthâpossibly 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 Chronbachâs alpha of Îą = .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
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Contribution of encouraging the future use of biomethane to resolving sustainability and energy security challenges: The case of the UK
The focus of this research is the potential of biomethane in Britain's gas grid. It examines its relative ability to address Britain's sustainability and energy security challenges from an economic perspective. Such research is important because UK is wedded to gas for heat production and power generation and is increasingly dependent on imported gas, in line with shrinking domestic production, and uncertain future trading relationships. Also, dependency on natural gas, threatens Britain achieving its legally-binding carbon budgets. The study included a thorough literature review, primary research to finally uncover the views of key UK market participants plus analytical modelling. The findings reveal that the market is cautiously optimistic, despite reservations regarding feedstock availability and the impending cessation of subsidy approvals. Investors are in greater need of long-term certainty, however, and the challenge of decarbonising heat and heavy-duty transport warrants this. Retail price premiums are polarised but, in line with wholesale costs, relatively high compared to electricity. The key recommendation is for the policymakers to follow precedents in renewable electricity and liquid biofuels, by mandating that energy suppliers, owners of heavy-duty road fleets and occupiers of new buildings purchase biomethane. In tandem, feedstock and grid-entry restrictions must be tackled creatively
Tacit rejection of policy and teacher ambivalence â insights into English language teaching in Bahrain through actorsâ perceptions
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
It has been established that traditional lectures ARE NOT best for student learning â 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
HIV and drug abuse mediate astrocyte senescence in a βâcateninâdependent manner leading to neuronal toxicity
Emerging evidence suggests that cell senescence plays an important role in agingâassociated diseases including neurodegenerative diseases. HIV leads to a spectrum of neurologic diseases collectively termed HIVâassociated neurocognitive disorders (HAND). Drug abuse, particularly methamphetamine (meth), is a frequently abused psychostimulant among HIV+ individuals and its abuse exacerbates HAND. The mechanism by which HIV and meth lead to brain cell dysregulation is not entirely clear. In this study, we evaluated the impact of HIV and meth on astrocyte senescence using in vitro and several animal models. Astrocytes constitute up to 50% of brain cells and play a pivotal role in marinating brain homeostasis. We show here that HIV and meth induce significant senescence of primary human fetal astrocytes, as evaluated by induction of senescence markers (βâgalactosidase and p16INK
4A), senescenceâassociated morphologic changes, and cell cycle arrest. HIVâ and methâmediated astrocyte senescence was also demonstrated in three small animal models (humanized mouse model of HIV/NSGâhuPBMCs, HIVâtransgenic rats, and in a meth administration rat model). Senescent astrocytes in turn mediated neuronal toxicity. Further, we show that βâcatenin, a proâsurvival/proliferation transcriptional coâactivator, is downregulated by HIV and meth in human astrocytes and this downregulation promotes astrocyte senescence while induction of βâcatenin blocks HIVâ and methâmediated astrocyte senescence. These studies, for the first time, demonstrate that HIV and meth induce astrocyte senescence and implicate the βâcatenin pathway as potential therapeutic target to overcome astrocyte senescence
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