40,535 research outputs found
Computer system for monitoring radiorepirometry data
System monitors expired breath patterns simultaneously from four small animals after they have been injected with carbon-14 substrates. It has revealed significant quantitative differences in oxidation patterns of glucose following such mild treatments of rats as a change in diet or environment
Red Giants in the Small Magellanic Cloud. II. Metallicity Gradient and Age-Metallicity Relation
We present results from the largest CaII triplet line metallicity study of
Small Magellanic Cloud (SMC) field red giant stars to date, involving 3037
objects spread across approximately 37.5 sq. deg., centred on this galaxy. We
find a median metallicity of [Fe/H]=-0.99+/-0.01, with clear evidence for an
abundance gradient of -0.075+/-0.011 dex / deg. over the inner 5 deg. We
interpret the abundance gradient to be the result of an increasing fraction of
young stars with decreasing galacto-centric radius, coupled with a uniform
global age-metallicity relation. We also demonstrate that the age-metallicity
relation for an intermediate age population located 10kpc in front of the NE of
the Cloud is indistinguishable from that of the main body of the galaxy,
supporting a prior conjecture that this is a stellar analogue of the Magellanic
Bridge. The metal poor and metal rich quartiles of our RGB star sample (with
complementary optical photometry from the Magellanic Clouds Photometric Survey)
are predominantly older and younger than approximately 6Gyr, respectively.
Consequently, we draw a link between a kinematical signature, tentatively
associated by us with a disk-like structure, and the upsurges in stellar
genesis imprinted on the star formation history of the central regions of the
SMC. We conclude that the increase in the star formation rate around 5-6Gyr ago
was most likely triggered by an interaction between the SMC and LMC.Comment: To appear in MNRA
Red Giants in the Small Magellanic Cloud. I. Disk and Tidal Stream Kinematics
We present results from an extensive spectroscopic survey of field stars in
the Small Magellanic Cloud (SMC). 3037 sources, predominantly first-ascent red
giants, spread across roughly 37.5 sq. deg, are analysed. The line of sight
velocity field is dominated by the projection of the orbital motion of the SMC
around the LMC/Milky Way. The residuals are inconsistent with both a
non-rotating spheroid and a nearly face on disk system. The current sample and
previous stellar and HI kinematics can be reconciled by rotating disk models
with line of nodes position angle, theta, ~ 120-130 deg., moderate inclination
(i ~ 25-70 deg.), and rotation curves rising at 20-40 km/s/kpc. The metal-poor
stars exhibit a lower velocity gradient and higher velocity dispersion than the
metal-rich stars. If our interpretation of the velocity patterns as bulk
rotation is appropriate, then some revision to simulations of the SMC orbit is
required since these are generally tuned to the SMC disk line-of-nodes lying in
a NE-SW direction. Residuals show strong spatial structure indicative of
non-circular motions that increase in importance with increasing distance from
the SMC centre. Kinematic substructure in the north-west part of our survey
area is associated with the tidal tail or Counter-Bridge predicted by
simulations. Lower line-of-sight velocities towards the Wing and the larger
velocities just beyond the SW end of the SMC Bar are probably associated with
stellar components of the Magellanic Bridge and Counter-Bridge, respectively.
Our results reinforce the notion that the intermediate-age stellar population
of the SMC is subject to substantial stripping by external forces.Comment: To appear in MNRA
Project Tektite 1 - A multiagency 60 day saturated dive conducted by the United States Navy, the National Aeronautics and Space Administration, the Department of the Interior, and the General Electric Company Summary report
Underwater research in ocean floor habitat for 60 day evaluation of supporting facilities at Virgin Islands for Tektite 1 projec
The evolution of electron density and temperature distributions in the topside ionosphere during magnetic storms
The latitudinal distributions of electron density and temperature during geomagnetic storms in the mid-latitude topside ionosphere are observed to change in a manner than can be related to the evolution of ring current particle populations. The region of auroral precipitation is characterized by correlated increases in electron temperature and density. Equatorwards of this region, there is a broad belt of elevated electron temperatures and depressed electron densities which is usually much broader than any stable auroral red arc distinguishable from the ground, but which is nevertheless the same basic physical phenomenon. The changes of position of this belt can be related to prior bursts of geomagnetic activity and injection of ring current particles into the magnetosphere
Single atom-scale diamond defect allows large Aharonov-Casher phase
We propose an experiment that would produce and measure a large
Aharonov-Casher (A-C) phase in a solid-state system under macroscopic motion. A
diamond crystal is mounted on a spinning disk in the presence of a uniform
electric field. Internal magnetic states of a single NV defect, replacing
interferometer trajectories, are coherently controlled by microwave pulses. The
A-C phase shift is manifested as a relative phase, of up to 17 radians, between
components of a superposition of magnetic substates, which is two orders of
magnitude larger than that measured in any other atom-scale quantum system.Comment: 5 pages, 2 figure
Shocks in asymmetric simple exclusion processes of interacting particles
In this paper, we study shocks and related transitions in asymmetric simple
exclusion processes of particles with nearest neighbor interactions. We
consider two kinds of inter-particle interactions. In one case, the
particle-hole symmetry is broken due to the interaction. In the other case,
particles have an effective repulsion due to which the particle-current-density
drops down near the half filling. These interacting particles move on a one
dimensional lattice which is open at both the ends with injection of particles
at one end and withdrawal of particles at the other. In addition to this, there
are possibilities of attachments or detachments of particles to or from the
lattice with certain rates. The hydrodynamic equation that involves the exact
particle current-density of the particle conserving system and additional terms
taking care of the attachment-detachment kinetics is studied using the
techniques of boundary layer analysis.Comment: 10 pages, 8 figure
Cosmological Constraints from Moments of the Thermal Sunyaev-Zel'dovich Effect
In this paper, we explain how moments of the thermal Sunyaev-Zel'dovich (tSZ)
effect can constrain both cosmological parameters and the astrophysics of the
intracluster medium (ICM). As the tSZ signal is strongly non-Gaussian, higher
moments of tSZ maps contain useful information. We first calculate the
dependence of the tSZ moments on cosmological parameters, finding that higher
moments scale more steeply with sigma_8 and are sourced by more massive galaxy
clusters. Taking advantage of the different dependence of the variance and
skewness on cosmological and astrophysical parameters, we construct a
statistic, ||/^1.4, which cancels much of the dependence on cosmology
(i.e., sigma_8) yet remains sensitive to the astrophysics of intracluster gas
(in particular, to the gas fraction in low-mass clusters). Constraining the ICM
astrophysics using this statistic could break the well-known degeneracy between
cosmology and gas physics in tSZ measurements, allowing for tight constraints
on cosmological parameters. Although detailed simulations will be needed to
fully characterize the accuracy of this technique, we provide a first
application to data from the Atacama Cosmology Telescope and the South Pole
Telescope. We estimate that a Planck-like full-sky tSZ map could achieve a <1%
constraint on sigma_8 and a 1-sigma error on the sum of the neutrino masses
that is comparable to the existing lower bound from oscillation measurements.Comment: 11 pages, 12 figures, to be submitted to Phys. Rev. D; v2: 14 pages,
16 figures, matches PRD accepted version (changes from v1 include additional
calculations with primordial non-Gaussianity and a new appendix discussing
the tSZ kurtosis
System and method for moving a probe to follow movements of tissue
An apparatus is described for moving a probe that engages moving living tissue such as a heart or an artery that is penetrated by the probe, which moves the probe in synchronism with the tissue to maintain the probe at a constant location with respect to the tissue. The apparatus includes a servo positioner which moves a servo member to maintain a constant distance from a sensed object while applying very little force to the sensed object, and a follower having a stirrup at one end resting on a surface of the living tissue and another end carrying a sensed object adjacent to the servo member. A probe holder has one end mounted on the servo member and another end which holds the probe
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