7,100 research outputs found
Sub-Saturn Planet Candidates to HD 16141 and HD 46375
Precision Doppler measurements from the Keck/HIRES spectrometer reveal
periodic Keplerian velocity variations in the stars HD 16141 and HD 46375. HD
16141 (G5 IV) has a period of 75.8 d and a velocity amplitude of 11 m/s,
yielding a companion having Msini = 0.22 Mjup and a semimajor axis, a = 0.35
AU. HD 46375 (K1 IV/V) has a period of 3.024 d and a velocity amplitude of 35
m/s, yielding a companion with Msini=0.25 Mjup, a semimajor axis of a = 0.041
AU, and an eccentricity of 0.04 (consistent with zero). These companions
contribute to the rising planet mass function toward lower masses.Comment: 4 Figure
Differential regulation of bladder pain and voiding function by sensory afferent populations revealed by selective optogenetic activation
The effect of bedrest on various parameters of physiological function. part xiv- effect of bedrest on plasma levels and urinary excretion of 17-hydroxycorticosteroids
Bed rest effect on plasma levels and urinary excretion of hydroxycorticosteroid
Ten Low Mass Companions from the Keck Precision Velocity Survey
Ten new low mass companions have emerged from the Keck precision Doppler
velocity survey, with minimum (msini) masses ranging from 0.8 mjup to 0.34
msun. Five of these are planet candidates with msini < 12 mjup, two are brown
dwarf candidates with msini ~30 mjup, and three are low mass stellar
companions. Hipparcos astrometry reveals the orbital inclinations and masses
for three of the (more massive) companions, and it provides upper limits to the
masses for the rest. A new class of extrasolar planet is emerging,
characterized by nearly circular orbits and orbital radii greater than 1 AU.
The planet HD 4208b appears to be a member of this new class. The mass
distribution of extrasolar planets continues to exhibit a rapid rise from 10
mjup toward the lowest detectable masses near 1 msat.Comment: 26 pages, TeX, plus 13 postscript figure
Synthesis and characterization of Na03RhO206H2O - a semiconductor with a weak ferromagnetic component
We have prepared the oxyhydrate Na03RhO206H2O by extracting Na+ cations from
NaRhO2 and intercalating water molecules using an aqueous solution of Na2S2O8.
Synchrotron X-ray powder diffraction, thermogravimetric analysis (TGA), and
energy-dispersive x-ray analysis (EDX) reveal that a non-stoichiometric
Na03(H2O)06 network separates layers of edge-sharing RhO6 octahedra containing
Rh3+(4d6, S=0) and Rh4+ (4d5, S=1/2). The resistivities of NaRhO2 and
Na03RhO206H2O (T < 300) reveal insulating and semi-conducting behavior with
activation gaps of 134 meV and 7.8 meV, respectively. Both Na03RhO206H2O and
NaRhO2 show paramagnetism at room temperature, however, the sodium-deficient
sample exhibits simultaneously a weak but experimentally reproducible
ferromagnetic component. Both samples exhibit a temperature-independent Pauli
paramagnetism, for NaRhO2 at T > 50 K and for Na03RhO206H2O at T > 25 K. The
relative magnitudes of the temperature-independent magnetic susceptibilities,
that of the oxide sample being half that of the oxyhydrate, is consistent with
a higher density of thermally accessible electron states at the Fermi level in
the hydrated sample. At low temperatures the magnetic moments rise sharply,
providing evidence of localized and weakl -ordered electronic spins.Comment: 15 fages 5 figures Solid State Communications in prin
Two New Candidate Planets in Eccentric Orbits
Doppler measurements of two G-type main-sequence stars, HD210277 and
HD168443, reveal Keplerian variations that imply the presence of companions
with masses (M sin i) of 1.28 and 5.04 M_Jup and orbital periods of 437 d and
58 d, respectively. The orbits have large eccentricities of e=0.45 and e=0.54,
respectively. All 9 known extrasolar planet candidates with a=0.2-2.5 AU have
orbital eccentricities greater than 0.1, higher than that of Jupiter (e=0.05).
Eccentric orbits may result from gravitational perturbations imposed by other
orbiting planets or stars, by passing stars in the dense star-forming cluster,
or by the protoplanetary disk. Based on published studies and our near-IR
adaptive optics images, HD210277 appears to be a single star. However, HD168443
exhibits a long-term velocity trend consistent with a close stellar companion,
as yet undetected directly.Comment: AASTeX, 31 pages including 10 Postscript figures, to appear in the
Astrophysical Journal (July 1999
Differential regulation of bladder pain and voiding function by sensory afferent populations revealed by selective optogenetic activation
Bladder-innervating primary sensory neurons mediate reflex-driven bladder function under normal conditions, and contribute to debilitating bladder pain and/or overactivity in pathological states. The goal of this study was to examine the respective roles of defined subtypes of afferent neurons in bladder sensation and function in vivo via direct optogenetic activation. To accomplish this goal, we generated transgenic lines that express a Channelrhodopsin-2-eYFP fusion protein (ChR2-eYFP) in two distinct populations of sensory neurons: TRPV1-lineage neurons (Trpv1Cre;Ai32, the majority of nociceptors) and Nav1.8+ neurons (Scn10aCre;Ai32, nociceptors and some mechanosensitive fibers). In spinal cord, eYFP+ fibers in Trpv1Cre;Ai32 mice were observed predominantly in dorsal horn (DH) laminae I-II, while in Scn10aCre;Ai32 mice they extended throughout the DH, including a dense projection to lamina X. Fiber density correlated with number of retrogradely-labeled eYFP+ dorsal root ganglion neurons (82.2% Scn10aCre;Ai32 vs. 62% Trpv1Cre;Ai32) and degree of DH excitatory synaptic transmission. Photostimulation of peripheral afferent terminals significantly increased visceromotor responses to noxious bladder distension (30–50 mmHg) in both transgenic lines, and to non-noxious distension (20 mmHg) in Scn10aCre;Ai32 mice. Depolarization of ChR2+ afferents in Scn10aCre;Ai32 mice produced low- and high-amplitude bladder contractions respectively in 53% and 27% of stimulation trials, and frequency of high-amplitude contractions increased to 60% after engagement of low threshold (LT) mechanoreceptors by bladder filling. In Trpv1Cre;Ai32 mice, low-amplitude contractions occurred in 27% of trials before bladder filling, which was pre-requisite for light-evoked high-amplitude contractions (observed in 53.3% of trials). Potential explanations for these observations include physiological differences in the thresholds of stimulated fibers and their connectivity to spinal circuits
Enhanced charm hadroproduction due to nonlinear corrections to the DGLAP equations
We have studied the effects of nonlinear scale evolution of the parton
distribution functions to charm production in collisions at center-of-mass
energies of 5.5, 8.8 and 14 TeV. We find that the differential charm cross
section can be enhanced up to a factor of 4-5 at low . The enhancement is
quite sensitive to the charm quark mass and the renormalization/factorization
scales.Comment: 4 pages, 3 eps-figures. To appear in the proceedings of the
seventeenth international conference on Ultra-Relativistic Nucleus-Nucleus
Collisions (Quark Matter 2004
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