365 research outputs found
Smilin\u27 Through / words by Arthur A. Penn
Cover: photo of a woman in a fancy-dress Ball, Norma Talmadge; Publisher: M. Witmark and Sons (New York)https://egrove.olemiss.edu/sharris_c/1172/thumbnail.jp
Large-scale analysis of orthologs and paralogs under covarion-like and constant-but-different models of amino acid evolution.
Functional divergence between homologous proteins is expected to affect amino acid sequences in two main ways, which can be considered as proxies of biochemical divergence: a "covarion-like" pattern of correlated changes in evolutionary rates, and switches in conserved residues ("conserved but different"). Although these patterns have been used in case studies, a large-scale analysis is needed to estimate their frequency and distribution. We use a phylogenomic framework of animal genes to answer three questions: 1) What is the prevalence of such patterns? 2) Can we link such patterns at the amino acid level with selection inferred at the codon level? 3) Are patterns different between paralogs and orthologs? We find that covarion-like patterns are more frequently detected than "constant but different," but that only the latter are correlated with signal for positive selection. Finally, there is no obvious difference in patterns between orthologs and paralogs
Stacked Search for Gravitational Waves from the 2006 SGR 1900+14 Storm
We present the results of a LIGO search for short-duration gravitational
waves (GWs) associated with the 2006 March 29 SGR 1900+14 storm. A new search
method is used, "stacking'' the GW data around the times of individual
soft-gamma bursts in the storm to enhance sensitivity for models in which
multiple bursts are accompanied by GW emission. We assume that variation in the
time difference between burst electromagnetic emission and potential burst GW
emission is small relative to the GW signal duration, and we time-align GW
excess power time-frequency tilings containing individual burst triggers to
their corresponding electromagnetic emissions. We use two GW emission models in
our search: a fluence-weighted model and a flat (unweighted) model for the most
electromagnetically energetic bursts. We find no evidence of GWs associated
with either model. Model-dependent GW strain, isotropic GW emission energy
E_GW, and \gamma = E_GW / E_EM upper limits are estimated using a variety of
assumed waveforms. The stacking method allows us to set the most stringent
model-dependent limits on transient GW strain published to date. We find E_GW
upper limit estimates (at a nominal distance of 10 kpc) of between 2x10^45 erg
and 6x10^50 erg depending on waveform type. These limits are an order of
magnitude lower than upper limits published previously for this storm and
overlap with the range of electromagnetic energies emitted in SGR giant flares.Comment: 7 pages, 3 figure
First measurement of the Hubble Constant from a Dark Standard Siren using the Dark Energy Survey Galaxies and the LIGO/Virgo Binary–Black-hole Merger GW170814
International audienceWe present a multi-messenger measurement of the Hubble constant H 0 using the binary–black-hole merger GW170814 as a standard siren, combined with a photometric redshift catalog from the Dark Energy Survey (DES). The luminosity distance is obtained from the gravitational wave signal detected by the Laser Interferometer Gravitational-Wave Observatory (LIGO)/Virgo Collaboration (LVC) on 2017 August 14, and the redshift information is provided by the DES Year 3 data. Black hole mergers such as GW170814 are expected to lack bright electromagnetic emission to uniquely identify their host galaxies and build an object-by-object Hubble diagram. However, they are suitable for a statistical measurement, provided that a galaxy catalog of adequate depth and redshift completion is available. Here we present the first Hubble parameter measurement using a black hole merger. Our analysis results in , which is consistent with both SN Ia and cosmic microwave background measurements of the Hubble constant. The quoted 68% credible region comprises 60% of the uniform prior range [20, 140] km s−1 Mpc−1, and it depends on the assumed prior range. If we take a broader prior of [10, 220] km s−1 Mpc−1, we find (57% of the prior range). Although a weak constraint on the Hubble constant from a single event is expected using the dark siren method, a multifold increase in the LVC event rate is anticipated in the coming years and combinations of many sirens will lead to improved constraints on H 0
A blood RNA signature for tuberculosis disease risk: a prospective cohort study.
BACKGROUND: Identification of blood biomarkers that prospectively predict progression of Mycobacterium tuberculosis infection to tuberculosis disease might lead to interventions that combat the tuberculosis epidemic. We aimed to assess whether global gene expression measured in whole blood of healthy people allowed identification of prospective signatures of risk of active tuberculosis disease. METHODS: In this prospective cohort study, we followed up healthy, South African adolescents aged 12-18 years from the adolescent cohort study (ACS) who were infected with M tuberculosis for 2 years. We collected blood samples from study participants every 6 months and monitored the adolescents for progression to tuberculosis disease. A prospective signature of risk was derived from whole blood RNA sequencing data by comparing participants who developed active tuberculosis disease (progressors) with those who remained healthy (matched controls). After adaptation to multiplex quantitative real-time PCR (qRT-PCR), the signature was used to predict tuberculosis disease in untouched adolescent samples and in samples from independent cohorts of South African and Gambian adult progressors and controls. Participants of the independent cohorts were household contacts of adults with active pulmonary tuberculosis disease. FINDINGS: Between July 6, 2005, and April 23, 2007, we enrolled 6363 participants from the ACS study and 4466 from independent South African and Gambian cohorts. 46 progressors and 107 matched controls were identified in the ACS cohort. A 16 gene signature of risk was identified. The signature predicted tuberculosis progression with a sensitivity of 66·1% (95% CI 63·2-68·9) and a specificity of 80·6% (79·2-82·0) in the 12 months preceding tuberculosis diagnosis. The risk signature was validated in an untouched group of adolescents (p=0·018 for RNA sequencing and p=0·0095 for qRT-PCR) and in the independent South African and Gambian cohorts (p values <0·0001 by qRT-PCR) with a sensitivity of 53·7% (42·6-64·3) and a specificity of 82·8% (76·7-86) in the 12 months preceding tuberculosis. INTERPRETATION: The whole blood tuberculosis risk signature prospectively identified people at risk of developing active tuberculosis, opening the possibility for targeted intervention to prevent the disease. FUNDING: Bill & Melinda Gates Foundation, the National Institutes of Health, Aeras, the European Union, and the South African Medical Research Council
Curriculum in early childhood education: critical questions about content, coherence, and control
A continuing struggle over curriculum in early childhood education is evident in contemporary research and debate at national and international levels. This reflects the dominant influence of developmental psychology in international discourses, and in policy frameworks that determine approaches to curriculum, pedagogy, and assessment. Focusing on early childhood education, we argue that this struggle generates critical questions about three significant themes within curriculum theory: content, coherence, and control. We outline two positions from which these themes can be understood: Developmental and Educational Psychology and contemporary policy frameworks. We argue that within and between these positions, curriculum content, coherence, and control are viewed in different and sometimes oppositional ways. Following this analysis, we propose that a focus on ‘working theories’ as a third position offers possibilities for addressing some of these continuing struggles, by exploring different implications for how content, coherence, and control might be understood. We conclude that asking critical questions of curriculum in early childhood education is a necessary endeavour to develop alternative theoretical frameworks for understanding the ways in which curriculum can be considered alongside pedagogy, assessment, play, and learning
GW170104: Observation of a 50-Solar-Mass Binary Black Hole Coalescence at Redshift 0.2
We describe the observation of GW170104, a gravitational-wave signal produced by the coalescence of a pair of stellar-mass black holes. The signal was measured on January 4, 2017 at 10: 11: 58.6 UTC by the twin advanced detectors of the Laser Interferometer Gravitational-Wave Observatory during their second observing run, with a network signal-to-noise ratio of 13 and a false alarm rate less than 1 in 70 000 years. The inferred component black hole masses are 31.2(-6.0)(+8.4)M-circle dot and 19.4(-5.9)(+5.3)M(circle dot) (at the 90% credible level). The black hole spins are best constrained through measurement of the effective inspiral spin parameter, a mass-weighted combination of the spin components perpendicular to the orbital plane, chi(eff) =
-0.12(-0.30)(+0.21) . This result implies that spin configurations with both component spins positively aligned with the orbital angular momentum are disfavored. The source luminosity distance is 880(-390)(+450) Mpc corresponding to a redshift of z = 0.18(-0.07)(+0.08) . We constrain the magnitude of modifications to the gravitational-wave dispersion relation and perform null tests of general relativity. Assuming that gravitons are dispersed in vacuum like massive particles, we bound the graviton mass to m(g) <= 7.7 x 10(-23) eV/c(2). In all cases, we find that GW170104 is consistent with general relativity
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