3,155 research outputs found

    The Radio Spectrum of TVLM513-46546: Constraints on the Coronal Properties of a Late M Dwarf

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    We explore the radio emission from the M9 dwarf, TVLM513-46546, at multiple radio frequencies, determining the flux spectrum of persistent radio emission, as well as constraining the levels of circular polarization. Detections at both 3.6 and 6 cm provide spectral index measurement α\alpha (where SΜ∝Μα_{\nu} \propto \nu^{\alpha}) of −0.4±0.1-0.4\pm0.1. A detection at 20 cm suggests that the spectral peak is between 1.4 and 5 GHz. The most stringent upper limits on circular polarization are at 3.6 and 6 cm, with V/I<V/I <15%. These characteristics agree well with those of typical parameters for early to mid M dwarfs, confirming that magnetic activity is present at levels comparable with those extrapolated from earlier M dwarfs. We apply analytic models to investigate the coronal properties under simple assumptions of dipole magnetic field geometry and radially varying nonthermal electron density distributions. Requiring the spectrum to be optically thin at frequencies higher than 5 GHz and reproducing the observed 3.6 cm fluxes constrains the magnetic field at the base to be less than about 500 G. There is no statistically significant periodicity in the 3.6 cm light curve, but it is consistent with low-level variability.Comment: 11 pages, 2 figures Accepted for publication in the Astrophysical Journa

    Detecting Bose-Einstein condensation of exciton-polaritons via electron transport

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    We examine the Bose-Einstein condensation of exciton-polaritons in a semiconductor microcavity via an electrical current. We propose that by embedding a quantum dot p-i-n junction inside the cavity, the tunneling current through the device can reveal features of condensation due to a one-to-one correspondence of the photons to the condensate polaritons. Such a device can also be used to observe the phase interference of the order parameters from two condensates.Comment: 5 Pages, 3 Figure

    Injector for liquid fueled rocket engine

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    An injector for liquid fueled rocket engines wherein a generally flat core having a frustoconical dome attached to one side of the core to serve as a manifold for a first liquid, with the core having a generally circular configuration having an axis. The other side of the core has a plurality of concentric annular first slots and a plurality of annular concentric second slots alternating with the first slots, the second slots having a greater depth than said first slots. A bore extends through the core for inletting a second liquid into said core, the bore intersecting the second slots to feed the second liquid into the second slots. The core also has a plurality of first passageways leading from the manifold to the first annular slots for feeding the first liquid into said first slots. A faceplate brazed to said other side of the core is provided with apertures extending from the first and second slots through said face plate, these apertures being positioned to direct fuel and liquid oxygen into contact with each other in the combustion chamber. The first liquid may be liquid oxygen and the second liquid may be kerosene or liquid hydrogen

    The password is praise: content of feedback affects categorization of feedback sources.

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    PublishedJournal ArticleIn three experimental studies, we investigated the effect of the content of group-directed feedback on categorization of the feedback source as an ingroup or an outgroup member. In all studies, feedback valence (criticism vs. praise) and the attributional content of feedback (attributing outcomes to internal properties of the group vs. external circumstances) were experimentally manipulated. The results demonstrated that anonymous (Study 1) and ambiguous (Studies 2 and 3) sources of feedback are more likely to be seen as (typical) ingroup members when they provide praise rather than criticism. In addition, in all studies there was a significant interaction between valence and the attributional content of feedback, such that sources of praise were more likely to be seen as ingroup members when they attributed the group's success to internal (rather than external) causes, while the opposite was observed for critics. These effects were mediated by perceived group image threat. Implications for research on group-based feedback and social categorization are discussed

    Concerted changes in tropical forest structure and dynamics: evidence from 50 South American long-term plots

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    Several widespread changes in the ecology of old-growth tropical forests have recently been documented for the late twentieth century, in particular an increase in stem turnover (pan-tropical), and an increase in above-ground biomass (neotropical). Whether these changes are synchronous and whether changes in growth are also occurring is not known. We analysed stand-level changes within 50 long-term. monitoring plots from across South America spanning 1971-2002. We show that: (i) basal area (BA: sum of the cross-sectional areas of all trees in a plot) increased significantly over time (by 0.10 +/- 0.04 m(2) ha(-1) yr(-1), mean +/- 95% CI); as did both (ii) stand-level BA growth rates (sum of the increments of BA of surviving trees and BA of new trees that recruited into a plot); and (iii) stand-level BA mortality rates (sum of the cross-sectional areas of all trees that died in a plot). Similar patterns were observed on a per-stem basis: (i) stem density (number of stems per hectare; 1 hectare is 10(4) m(2)) increased significantly over time (0.94 +/- 0.63 stems ha(-1) yr(-1)); as did both (ii) stem recruitment rates; and (iii) stem mortality rates. In relative terms, the pools of BA and stem density increased by 0.38 +/- 0.15% and 0.18 +/- 0.12% yr(-1), respectively. The fluxes into and out of these pools-stand-level BA growth, stand-level BA mortality, stem recruitment and stem mortality rates-increased, in relative terms, by an order of magnitude more. The gain terms (BA growth, stem recruitment) consistently exceeded the loss terms (BA loss, stem mortality) throughout the period, suggesting that whatever process is driving these changes was already acting before the plot network was established. Large long-term increases in stand-level BA growth and simultaneous increases in stand BA and stem density imply a continent-wide increase in resource availability which is increasing net primary productivity and altering forest dynamics. Continent-wide changes in incoming solar radiation, and increases in atmospheric concentrations of CO2 and air temperatures may have increased resource supply over recent decades, thus causing accelerated growth and increased dynamism across the world's largest tract of tropical forest

    A systematic review of the organizational, environmental, professional and child and family factors influencing the timing of admission to hospital for children with serious infectious illness

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    Abstract Background Infection, particularly in the first 5 years of life, is a major cause of childhood deaths globally, many deaths from infections such as pneumonia and meningococcal disease are avoidable, if treated in time. Some factors that contribute to morbidity and mortality can be modified. These include organisational and environmental factors as well as those related to the child, family or professional. Objective Examine what organizational and environmental factors and individual child, family and professional factors affect timing of admission to hospital for children with a serious infectious illness. Design Systematic review. Data sources Key search terms were identified and used to search CINAHL Plus, Medline, ASSIA, Web of Science, The Cochrane Library, Joanna Briggs Institute Database of Systematic Review. Study appraisal methods Primary research (e.g. quantitative, qualitative and mixed methods studies) and literature reviews (e.g., systematic, scoping and narrative) were included if participants included or were restricted to children under 5 years of age with serious infectious illnesses, included parents and/or first contact health care professionals in primary care, urgent and emergency care and where the research had been conducted in OECD high income countries. The Mixed Methods Appraisal Tool was used to review the methodological quality of the studies. Main findings Thirty-six papers were selected for full text review; 12 studies fitted the inclusion criteria. Factors influencing the timing of admission to hospital included the variability in children’s illness trajectories and pathways to hospital, parental recognition of symptoms and clinicians non-recognition of illness severity, parental help-seeking behaviour and clinician responses, access to services, use and non-use of ‘gut feeling’ by clinicians, and sub-optimal management within primary, secondary and tertiary services. Conclusions The pathways taken by children with a serious infectious illness to hospital are complex and influenced by a variety of potentially modifiable individual, organisational, environmental and contextual factors. Supportive, accessible, respectful services that provide continuity, clear communication, advice and safety-netting are important as is improved training for clinicians and a mandate to attend to ‘gut feeling’. Implications Relatively simple interventions such as improved communication have the potential to improve the quality of care and reduce morbidity and mortality in children with a serious infectious illness

    A new Holocene relative sea-level curve for western Brittany (France): Insights on isostatic dynamics along the Atlantic coasts of north-western Europe

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    International audienceThis study presents new Relative Sea Level (RSL) data that were obtained in the Finistùre region (Western tip of Brittany, France) and the implications those data have for the understanding of the isostatic dynamics across north-western Europe, and more specifically along the Atlantic and Channel coasts. New stratigraphic sequences were obtained and analyzed to derive 24 new Sea-level Index Points, in which 6 are basal. These new data considerably increase the knowledge we have of the RSL evolution along the coasts of Western Brittany since the last 8 kyr B.P. From this new dataset, RSL was estimated to rise continuously over the last 8 kyr with a major inflection at ca. 6 kyr cal. BP. Our results show large vertical discrepancies between the RSL records of Brittany and South-Western UK, with the latter plotting several meters below the new data. From this comparison we suggest that the two regions underwent a very different pattern and/or amplitude of subsidence during the last 8 kyr which has implications for the spatial and temporal pattern of the peripheral bulge of the European ice sheets. We compared our data against predictions from Glacio-Isostatic Adjustment models (GIA models). There are large misfits between RSL observations and the predictions of the global (ICE-5G (VM2a) – Peltier, 2004, GLAC1-b – Tarasov and Peltier, 2002; Tarasov et al., 2012, Briggs et al., 2014) and regional UK models (“BIIS” – Bradley et al., 2009; Bradley et al., 2011; “Kuchar”- Kuchar et al., 2012), which can't be resolved through significant changes to the deglaciation history and size of the British–Irish Ice sheet. Paleo-tidal modelling corrections indicate regional changes in the tidal ranges played a negligible role in the data-model misfits. Hence, we propose that the misfits are due to some combination of: (i) unaccounted mass-loss of far-field ice-sheets (Antarctic ice-Sheet or Laurentide Ice-Sheet), (ii) unresolved differences in the deglaciation history and size of the Fennoscandian Ice sheet or, more likely, (iii) significant lateral variations in the Earth's structure across the English Channel

    Type Ia Supernovae Rates and Galaxy Clustering from the CFHT Supernova Legacy Survey

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    The Canada-France-Hawaii Telescope Supernova Legacy Survey (SNLS) has created a large homogeneous database of intermediate redshift (0.2 < z < 1.0) type Ia supernovae (SNe Ia). The SNLS team has shown that correlations exist between SN Ia rates, properties, and host galaxy star formation rates. The SNLS SN Ia database has now been combined with a photometric redshift galaxy catalog and an optical galaxy cluster catalog to investigate the possible influence of galaxy clustering on the SN Ia rate, over and above the expected effect due to the dependence of SFR on clustering through the morphology-density relation. We identify three cluster SNe Ia, plus three additional possible cluster SNe Ia, and find the SN Ia rate per unit mass in clusters at intermediate redshifts is consistent with the rate per unit mass in field early-type galaxies and the SN Ia cluster rate from low redshift cluster targeted surveys. We also find the number of SNe Ia in cluster environments to be within a factor of two of expectations from the two component SNIa rate model.Comment: 21 pages, 2 figures, 6 tables, accepted for publication in A

    GLI1 confers profound phenotypic changes upon LNCaP prostate cancer cells that include the acquisition of a hormone independent state

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    The GLI (GLI1/GLI2) transcription factors have been implicated in the development and progression of prostate cancer although our understanding of how they actually contribute to the biology of these common tumours is limited. We observed that GLI reporter activity was higher in normal (PNT-2) and tumourigenic (DU145 and PC-3) androgen-independent cells compared to androgen-dependent LNCaP prostate cancer cells and, accordingly, GLI mRNA levels were also elevated. Ectopic expression of GLI1 or the constitutively active NGLI2 mutant induced a distinct cobblestone-like morphology in LNCaP cells that, regarding the former, correlated with increased GLI2 as well as expression of the basal/stem-like markers CD44, beta1-integrin, Np63 and BMI1, and decreased expression of the luminal marker AR (androgen receptor). LNCaP-GLI1 cells were viable in the presence of the AR inhibitor bicalutamide and gene expression profiling revealed that the transcriptome of LNCaP-GLI1 cells was significantly closer to DU145 and PC-3 cells than to control LNCaP-pBP (empty vector) cells, as well as identifying LCN2/NGAL as a highly induced transcript which is associated with hormone independence in breast and prostate cancer. Functionally, LNCaP-GLI1 cells displayed greater clonal growth and were more invasive than control cells but they did not form colonies in soft agar or prostaspheres in suspension suggesting that they do not possess inherent stem cell properties. Moreover, targeted suppression of GLI1 or GLI2 with siRNA did not reverse the transformed phenotype of LNCaP-GLI1 cells nor did double GLI1/GLI2 knockdowns activate AR expression in DU145 or PC-3 cells. As such, early targeting of the GLI oncoproteins may hinder progression to a hormone independent state but a more detailed understanding of the mechanisms that maintain this phenotype is required to determine if their inhibition will enhance the efficacy of anti-hormonal therapy through the induction of a luminal phenotype and increased dependency upon AR function
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