366 research outputs found
Ătude des variations de paramĂštres anatomiques et endocriniens chez l'anguille europĂ©enne (Anguilla anguilla) femelle, sĂ©dentaire et d'avalaison : application Ă la caractĂ©risation du stade argentĂ©
The near-infrared size-luminosity relations for Herbig Ae/Be disks
We report the results of a sensitive K-band survey of Herbig Ae/Be disk sizes
using the 85-m baseline Keck Interferometer. Targets were chosen to span the
maximum range of stellar properties to probe the disk size dependence on
luminosity and effective temperature. For most targets, the measured
near-infrared sizes (ranging from 0.2 to 4 AU) support a simple disk model
possessing a central optically-thin (dust-free) cavity, ringed by hot dust
emitting at the expected sublimation temperatures (T_sub~1000-1500K).
Furthermore, we find a tight correlation of disk size with source luminosity R
propto L^(1/2) for Ae and late Be systems (valid over more than 2 decades in
luminosity), confirming earlier suggestions based on lower-quality data.
Interestingly, the inferred dust-free inner cavities of the highest luminosity
sources (Herbig B0-B3 stars) are under-sized compared to predictions of the
optically-thin cavity model, likely due to optically-thick gas within the inner
AU.Comment: Accepted by Astrophysical Journal; 24 pages, 4 figures, 4 table
Cross-Platform Comparison of Caenorhabditis elegans Tissue Extraction Strategies for Comprehensive Metabolome Coverage
Oligodendrocyte differentiation from adult multipotent stem cells is modulated by glutamate
We used multipotent stem cells (MSCs) derived from the young rat subventricular zone (SVZ) to study the effects of glutamate in oligodendrocyte maturation. Glutamate stimulated oligodendrocyte differentiation from SVZ-derived MSCs through the activation of specific N-methyl--aspartate (NMDA) receptor subunits. The effect of glutamate and NMDA on oligodendrocyte differentiation was evident in both the number of newly generated oligodendrocytes and their morphology. In addition, the levels of NMDAR1 and NMDAR2A protein increased during differentiation, whereas NMDAR2B and NMDAR3 protein levels decreased, suggesting differential expression of NMDA receptor subunits during maturation. Microfluorimetry showed that the activation of NMDA receptors during oligodendrocyte differentiation elevated cytosolic calcium levels and promoted myelination in cocultures with neurons. Moreover, we observed that stimulation of MSCs by NMDA receptors induced the generation of reactive oxygen species (ROS), which were negatively modulated by the NADPH inhibitor apocynin, and that the levels of ROS correlated with the degree of differentiation. Taken together, these findings suggest that ROS generated by NADPH oxidase by the activation of NMDA receptors promotes the maturation of oligodendrocytes and favors myelination
Interferometer Observations of Subparsec-scale Infrared Emission in the Nucleus of NGC 4151
We report novel, high-angular resolution interferometric measurements that
imply the near-infrared nuclear emission in NGC 4151 is unexpectedly compact.
We have observed the nucleus of NGC 4151 at 2.2 microns using the two 10-meter
Keck telescopes as an interferometer and find a marginally resolved source ~0.1
pc in diameter. Our measurements rule out models in which a majority of the K
band nuclear emission is produced on scales larger than this size. The
interpretation of our measurement most consistent with other observations is
that the emission mainly originates directly in the central accretion disk.
This implies that AGN unification models invoking hot, optically thick dust may
not be applicable to NGC 4151.Comment: 9 pages, 1 figure, accepted for publication in the Astrophysical
Journal, Letter
First Observation of CP Violation in B0->D(*)CP h0 Decays by a Combined Time-Dependent Analysis of BaBar and Belle Data
We report a measurement of the time-dependent CP asymmetry of B0->D(*)CP h0
decays, where the light neutral hadron h0 is a pi0, eta or omega meson, and the
neutral D meson is reconstructed in the CP eigenstates K+ K-, K0S pi0 or K0S
omega. The measurement is performed combining the final data samples collected
at the Y(4S) resonance by the BaBar and Belle experiments at the
asymmetric-energy B factories PEP-II at SLAC and KEKB at KEK, respectively. The
data samples contain ( 471 +/- 3 ) x 10^6 BB pairs recorded by the BaBar
detector and ( 772 +/- 11 ) x 10^6, BB pairs recorded by the Belle detector. We
measure the CP asymmetry parameters -eta_f S = +0.66 +/- 0.10 (stat.) +/- 0.06
(syst.) and C = -0.02 +/- 0.07 (stat.) +/- 0.03 (syst.). These results
correspond to the first observation of CP violation in B0->D(*)CP h0 decays.
The hypothesis of no mixing-induced CP violation is excluded in these decays at
the level of 5.4 standard deviations.Comment: 9 pages, 2 figures, submitted to Physical Review Letter
Improved Measurements of Partial Rate Asymmetry in B -> h h Decays
We report improved measurements of the partial rate asymmetry (Acp) in B -> h
h decays with 140fb^-1 of data collected with the Belle detector at the KEKB
e+e- collider. Here h stands for a charged or neutral pion or kaon and in total
five decay modes are included: K-+ pi+-, K0s pi-+, K-+ pi0, pi-+ pi0 and K0s
pi0. The flavor of the last decay mode is determined from the accompanying B
meson. Using a data sample 4.7 times larger than that of our previous
measurement, we find Acp(K-+ pi+-) -0.088+-0.035+-0.013, 2.4 sigma from zero.
Results for other decay modes are also presented.Comment: 9 pages, 1 figur
Observations of DG Tauri with the Keck Interferometer
We present the first science results from the Keck Interferometer, a
direct-detection infrared interferometer utilizing the two 10-meter Keck
telescopes. The instrument and system components are briefly described. We then
present observations of the T Tauri object DG Tau, which is resolved by the
interferometer. The resolved component has a radius of 0.12 to 0.24 AU,
depending on the assumed stellar and extended component fluxes and the model
geometry used. Possible origins and implications of the resolved emission are
discussed.Comment: 10 pages, 2 figures, to appear in ApJ Letter
Validation of a physician global assessment tool for vitiligo extent: Results of an international vitiligo expert meeting
Search for CP violation in the decay B0->D*+-D-+
We report a search for CP-violating asymmetry in B0 -> D*+- D-+ decays. The
analysis employs two methods of B0 reconstruction: full and partial. In the
full reconstruction method all daughter particles of the B0 are required to be
detected; the partial reconstruction technique requires a fully reconstructed
D- and only a slow pion from the D*+ -> D0 pi_slow+ decay. From a fit to the
distribution of the time interval corresponding to the distance between two B
meson decay points we calculate the CP-violating parameters and find the
significance of nonzero CP asymmetry to be 2.7 standard deviations.Comment: 4 pages, 3 figure
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