10,563 research outputs found
Spatial and Temporal Habitat Use of an Asian Elephant in Sumatra
Increasingly, habitat fragmentation caused by agricultural and human development has forced Sumatran elephants into relatively small areas, but there is little information on how elephants use these areas and thus, how habitats can be managed to sustain elephants in the future. Using a Global Positioning System (GPS) collar and a land cover map developed from TM imagery, we identified the habitats used by a wild adult female elephant (Elephas maximus sumatranus) in the Seblat Elephant Conservation Center, Bengkulu Province, Sumatra during 2007–2008. The marked elephant (and presumably her 40–60 herd mates) used a home range that contained more than expected medium canopy and open canopy land cover. Further, within the home range, closed canopy forests were used more during the day than at night. When elephants were in closed canopy forests they were most often near the forest edge vs. in the forest interior. Effective elephant conservation strategies in Sumatra need to focus on forest restoration of cleared areas and providing a forest matrix that includes various canopy types
Spinor dynamics in an antiferromagnetic spin-1 thermal Bose gas
We present experimental observations of coherent spin-population oscillations
in a cold thermal, Bose gas of spin-1 sodium-23 atoms. The population
oscillations in a multi-spatial-mode thermal gas have the same behavior as
those observed in a single-spatial-mode antiferromagnetic spinor Bose Einstein
condensate. We demonstrate this by showing that the two situations are
described by the same dynamical equations, with a factor of two change in the
spin-dependent interaction coefficient, which results from the change to
particles with distinguishable momentum states in the thermal gas. We compare
this theory to the measured spin population evolution after times up to a few
hundreds of ms, finding quantitative agreement with the amplitude and period.
We also measure the damping time of the oscillations as a function of magnetic
field.Comment: 5 pages, 3 figure
Observations On Chytridiaceous Parasites Of Phanerogams. Xi. A Physoderma On Agropyron Repens
Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/141220/1/ajb211721.pd
First Results from SPARO: Evidence for Large-Scale Toroidal Magnetic Fields in the Galactic Center
We have observed the linear polarization of 450 micron continuum emission
from the Galactic center, using a new polarimetric detector system that is
operated on a 2 m telescope at the South Pole. The resulting polarization map
extends ~ 170 pc along the Galactic plane and ~ 30 pc in Galactic latitude, and
thus covers a significant fraction of the central molecular zone. Our map shows
that this region is permeated by large-scale toroidal magnetic fields. We
consider our results together with radio observations that show evidence for
poloidal fields in the Galactic center, and with Faraday rotation observations.
We compare all of these observations with the predictions of a magnetodynamic
model for the Galactic center that was proposed in order to explain the
Galactic Center Radio Lobe as a magnetically driven gas outflow. We conclude
that the observations are basically consistent with the model.Comment: 11 pages, 2 figures, 1 table, submitted to ApJ Let
Perceptions of Environmental Supports for Physical Activity in African American and White Adults in a Rural County in South Carolina
INTRODUCTION: This study examined the association between perceptions of social and safety-related environmental attributes and physical activity (PA) and walking in African American and white adults. METHODS: In a random-digit–dial telephone survey, 1165 adults in a rural county in South Carolina answered questions about their perceptions of social and safety-related environmental supports for PA and their overall PA and walking behavior. Social perceptions included whether neighbors could be trusted or were perceived to be physically active. Safety-related perceptions included neighborhood safety, the safety of public recreation facilities, problems with unattended dogs, traffic volume, and streetlight quality. Logistic regression models were used to examine the associations between environmental supports and PA and walking stratified by race. RESULTS: No association between perceived neighborhood environmental supports and PA or walking was observed in African Americans. Among whites, individuals who perceived their neighbors as active were twice (95% confidence interval [CI], 1.19–3.25) as likely to report meeting the recommendation for PA compared with individuals who did not report their neighbors as active. Whites who perceived their neighbors as active were 2.5 times (95% CI, 1.54–4.08) as likely to report meeting the recommendations for walking than whites who did not, and whites who perceived their neighborhoods as safe were 1.8 times (95% CI, 1.03–3.12) as likely to report meeting the recommendations for walking than whites who did not. CONCLUSION: These data indicate that perceptions of certain social and safety-related environmental supports were strongly associated with meeting the recommendations for PA and walking among white but not African American adults
Landau-Khalatnikov two-fluid hydrodynamics of a trapped Bose gas
Starting from the quantum kinetic equation for the non-condensate atoms and
the generalized Gross-Pitaevskii equation for the condensate, we derive the
two-fluid hydrodynamic equations of a trapped Bose gas at finite temperatures.
We follow the standard Chapman-Enskog procedure, starting from a solution of
the kinetic equation corresponding to the complete local equilibrium between
the condensate and the non-condensate components. Our hydrodynamic equations
are shown to reduce to a form identical to the well-known Landau-Khalatnikov
two-fluid equations, with hydrodynamic damping due to the deviation from local
equilibrium. The deviation from local equilibrium within the thermal cloud
gives rise to dissipation associated with shear viscosity and thermal
conduction. In addition, we show that effects due to the deviation from the
diffusive local equilibrium between the condensate and the non-condensate
(recently considered by Zaremba, Nikuni and Griffin) can be described by four
frequency-dependent second viscosity transport coefficients. We also derive
explicit formulas for all the transport coefficients. These results are used to
introduce two new characteristic relaxation times associated with hydrodynamic
damping. These relaxation times give the rate at which local equilibrium is
reached and hence determine whether one is in the two-fluid hydrodynamic
region.Comment: 26 pages, 3 postscript figures, submitted to PR
Increasing stair climbing in a train station: effects of contextual variables and visibility
Accumulation of physical activity during daily living is a current public health target that is
influenced by the layout of the built environment. This study reports how the layout of the
environment may influence responsiveness to an intervention. Pedestrian choices (n = 41 717)
between stairs and the adjacent escalators were monitored for seven weeks in a train station
(Birmingham, UK). After a 3.5 week baseline period, a stair riser banner intervention to increase
stair climbing was installed on two staircases adjacent to escalators and monitoring continued for
a further 3.5 weeks. Logistic regression analyses revealed that the visibility of the intervention,
defined as the area of visibility in the horizontal plane opposite to the direction of travel (termed
the isovist) had a major effect on success of the intervention. Only the largest isovist produced
an increase in stair climbing (isovist=77.6 m2, OR = 1.10, CIs 1.02-1.19; isovist=40.7 m2, OR =
0.98, CIs 0.91-1.06; isovist=53.2 m2, OR = 1.00, CIs 0.95-1.06). Additionally, stair climbing was
more common during the morning rush hour (OR = 1.56, CIs 1.80-2.59) and at higher levels of
pedestrian traffic volume (OR = 1.92, CIs 1.68-2.21). The layout of the intervention site can
influence responsiveness to point-of-choice interventions. Changes to the design of train stations
may maximize the choice of the stairs at the expense of the escalator by pedestrians leaving the
station
Parity Invariance and Effective Light-Front Hamiltonians
In the light-front form of field theory, boost invariance is a manifest
symmetry. On the downside, parity and rotational invariance are not manifest,
leaving the possibility that approximations or incorrect renormalization might
lead to violations of these symmetries for physical observables. In this paper,
it is discussed how one can turn this deficiency into an advantage and utilize
parity violations (or the absence thereof) in practice for constraining
effective light-front Hamiltonians. More precisely, we will identify
observables that are both sensitive to parity violations and easily calculable
numerically in a non-perturbative framework and we will use these observables
to constrain the finite part of non-covariant counter-terms in effective
light-front Hamiltonians.Comment: REVTEX, 9 page
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