36,740 research outputs found
Plasma lactate concentrations in septic peritonitis: A retrospective study of 83 dogs (2007-2012)
Bayesian analysis of the radial velocities of HD 11506 reveals another planetary companion
We aim to demonstrate the efficiency of a Bayesian approach in analysing
radial velocity data by reanalysing a set of radial velocity measurements. We
present Bayesian analysis of a recently published set of radial velocity
measurements known to contain the signal of one extrasolar planetary candidate,
namely, HD 11506. The analysis is conducted using the Markov chain Monte Carlo
method and the resulting distributions of orbital parameters are tested by
performing direct integration of randomly selected samples with the
Bulirsch-Stoer method. The magnitude of the stellar radial velocity
variability, known as jitter, is treated as a free parameter with no
assumptions about its magnitude. We show that the orbital parameters of the
planet known to be present in the data correspond to a different solution when
the jitter is allowed to be a free parameter. We also show evidence of an
additional candidate, a 0.8 MJup planet with period of about 0.5 yr in orbit
around HD 11506. This second planet is inferred to be present with a high level
of confidence.Comment: 4 pages, 5 figures, to appear in A&
Planar cell polarity genes Frizzled3a, Vangl2, and Scribble are required for spinal commissural axon guidance
Background A fundamental feature of early nervous system development is the guidance of axonal projections to their targets in order to assemble neural circuits that control behavior. Spinal commissural neurons are an attractive model to investigate the multiple guidance cues that control growth cone navigation both pre- and post-midline crossing, as well as along both the dorsal–ventral (D–V) and anterior–posterior (A–P) axes. Accumulating evidence suggests that guidance of spinal commissural axons along the A–P axis is dependent on components of the planar cell polarity (PCP) signaling pathway. In the zebrafish, the earliest born spinal commissural neuron to navigate the midline and turn rostrally is termed commissural primary ascending (CoPA). Unlike mammalian systems, CoPA axons cross the midline as a single axon and allow an analysis of the role of PCP components in anterior pathfinding in single pioneering axons. Results Here, we establish CoPA cells in the zebrafish spinal cord as a model system for investigating the molecular function of planar cell polarity signaling in axon guidance. Using mutant analysis, we show that the functions of Fzd3a and Vangl2 in the anterior turning of commissural axons are evolutionarily conserved in teleosts. We extend our findings to reveal a role for the PCP gene scribble in the anterior guidance of CoPA axons. Analysis of single CoPA axons reveals that these commissural axons become responsive to PCP-dependent anterior guidance cues even prior to midline crossing. When midline crossing is prevented by dcc gene knockdown, ipsilateral CoPA axons still extend axons anteriorly in response to A–P guidance cues. We show that this ipsilateral anterior pathfinding that occurs in the absence of midline crossing is dependent on PCP signaling. Conclusion Our results demonstrate that anterior guidance decisions by CoPA axons are dependent on the function of planar cell polarity genes both prior to and after midline crossing
Countering the Norm, (Re)authoring Our Lives: The Promise Counterstorytelling Holds as a Research Methodology With LGBTQ Youth and Beyond
Counterstorytelling, a methodology that is rooted in critical race theory, is undergirded by principles that are beneficial to understanding the experiences of lesbian, gay, bisexual, transgender, and queer-identified (LGBTQ) young people from an intersectional perspective. Counterstorytelling holds promise as a method that creates opportunities for individual transformation and resistance to dominant narratives among young people facing systemic oppression. This article outlines the design and implementation of a counterstorytelling study with LGBTQ youth and reflects on the value and associated challenges of counterstorytelling as a participatory research method
Dissipation of mechanical energy in fused silica fibers
For thermal noise considerations of LIGO suspensions, the sources of
dissipation in the suspending fibers must be analyzed. To determine the
dissipation induced by the surface of fused silica fibers, we measured the
quality factor of fibers having various diameters. We measured a maximum
quality factor of 21 million and extrapolated to obtain an intrinsic quality
factor for fused silica of 30 million. Dissipation in the surface dominated at
diameters less than about 1 mm. We developed a method for characterizing
surface-induced dissipation that is independent of sample geometry or mode
shape.Comment: 20 pages, 6 figures, RevTeX. Minor Revisions. Accepted for
publication by Review of Scientific Instruments (29 June 1999). Projected
publication date: October 199
Photoluminescence-based measurements of the energy gap and diffusion length of Zn_3P_2
The steady-state photoluminescence spectra of zinc phosphide (Zn_3P_2) wafers have revealed a fundamental indirect band gap at 1.38 eV, in close proximity to the direct band gap at 1.50 eV. These values are consistent with the values for the indirect and direct band gaps obtained from analysis of the complex dielectric function deduced from spectroscopic ellipsometric measurements. Bulk minority carrier lifetimes of 20 ns were observed by time-resolved photoluminescence decay measurements, implying minority-carrier diffusion lengths of ≥ 7 µm
Glueball mass measurements from improved staggered fermion simulations
We present the first 2+1 flavour spectrum measurements of glueball states
using high statistics simulations with improved staggered fermions. We find a
spectrum consistent with quenched measurements of scalar, pseudoscalar
andtensor glueball states. The measurements were made using 5000 configurations
at a lattice spacing of 0.123 fm and pion mass of 280 MeV and 3000
configurations at 0.092 fm with a pion mass of 360 MeV. We see some evidence of
coupling to 2 pion states. We compare our results with the experimental
glueball candidate spectrum as well as quenched glueball estimates.Comment: 22 pages, 19 figures and 8 tables, minor additions on mixing
post-refere
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