14,992 research outputs found
Time Spent Working in Custody Influences Work Sample Test Battery Performance of Deputy Sheriffs Compared to Recruits
This study determined the influence of years spent working in custody on fitness measured by a state-specific testing battery (Work Sample Test Battery; WSTB) in deputy sheriffs. Retrospective analysis was conducted on one patrol school class (51 males, 13 females) divided into three groups depending on time spent working in custody: DS24 (<24 months; n = 20); DS2547 (25–47 months; n = 23); and DS48+ (≥48 months; n = 21). These groups were compared to a recruit class (REC; 219 males, 34 females) in the WSTB, which comprised five tasks completed for time: 99-yard (90.53-m) obstacle course (99OC); 165-pound (75-kg) dummy drag; six-foot (1.83-m) chain link fence (CLF) and solid wall (SW) climb; and 500-yard (457.2-m) run (500R). A univariate analysis of covariance (ANCOVA) (controlling for sex and age) with Bonferroni post hoc determined significant between-group differences. DS48+ were slower in the 99OC compared to the REC (p = 0.007) and performed the CLF and SW slower than all groups (p ≤ 0.012). DS24, DS2547, and DS48+ were all slower than REC in the 500R (p ≤ 0.002). Physical training should be implemented to maintain fitness and job-specific task performance in deputy sheriffs working custody, especially considering the sedentary nature of this work
Constraining the Milky Way potential using the dynamical kinematic substructures
We present a method to constrain the potential of the non-axisymmetric
components of the Galaxy using the kinematics of stars in the solar
neighborhood. The basic premise is that dynamical substructures in phase-space
(i.e. due to the bar and/or spiral arms) are associated with families of
periodic or irregular orbits, which may be easily identified in orbital
frequency space. We use the "observed" positions and velocities of stars as
initial conditions for orbital integrations in a variety of gravitational
potentials. We then compute their characteristic frequencies, and study the
structure present in the frequency maps. We find that the distribution of
dynamical substructures in velocity- and frequency-space is best preserved when
the integrations are performed in the "true" gravitational potential.Comment: 2 pages, 4 figures, to appear in the proceedings of "Assembling the
Puzzle of the Milky Way", Le Grand Bornand (Apr. 17-22, 2011
Sympathetic cooling route to Bose-Einstein condensate and Fermi-liquid mixtures
We discuss a sympathetic cooling strategy that can successfully mitigate
fermion-hole heating in a dilute atomic Fermi-Bose mixture and access the
temperature regime in which the fermions behave as a Fermi liquid. We introduce
an energy-based formalism to describe the temperature dynamics with which we
study a specific and promising mixture composed of 6Li and 87Rb. Analyzing the
harmonically trapped mixture, we find that the favourable features of this
mixture are further enhanced by using different trapping frequencies for the
two species.Comment: 4 pages, 2 figure
Comment on "Fisheries Management"
The recent article by O’Leary et al. (2011) raises an important question about the relationship between science and those who manage fisheries. They contend that fishery managers do not give due cognisance to scientific advice and consistently set Total Allowable Catches (TACs) above values advised by scientists (which they define as ‘‘political adjustment’’). The authors claim that the consequence of this is that there is a high probability of stock collapse in the next 40 years. They use a simulation model to argue that this probability may exceed 80% at the mean level of political adjustment adopted by managers, depending on the degree of environmental variability and life history strategy of the fish
The Age and Structure of the Galactic Bulge from Mira Variables
We report periods and JHKL observations for 648 oxygen-rich Mira variables
found in two outer bulge fields at b=-7 degrees and l=+/-8 degrees and combine
these with data on 8057 inner bulge Miras from the OGLE, Macho and 2MASS
surveys, which are concentrated closer to the Galactic centre. Distance moduli
are estimated for all these stars. Evidence is given showing that the bulge
structure is a function of age. The longer period Miras (log P > 2.6, age about
5 Gyr and younger) show clear evidence of a bar structure inclined to the line
of sight in both the inner and outer regions. The distribution of the shorter
period (metal-rich globular cluster age) Miras, appears spheroidal in the outer
bulge. In the inner region these old stars are also distributed differently
from the younger ones and possibly suggest a more complex structure. These data
suggest a distance to the Galactic centre, R0, of 8.9 kpc with an estimated
uncertainty of 0.4 kpc. The possible effect of helium enrichment on our
conclusions is discussed.Comment: Accepted for MNRAS, 12 pages, 12 figure
Patterns, causes, and consequences of marine larval dispersal
Quantifying the probability of larval exchange among marine populations is key to predicting local population dynamics and optimizing networks of marine protected areas. The pattern of connectivity among populations can be described by the measurement of a dispersal kernel. However, a statistically robust, empirical dispersal kernel has been lacking for any marine species. Here, we use genetic parentage analysis to quantify a dispersal kernel for the reef fish Elacatinus lori, demonstrating that dispersal declines exponentially with distance. The spatial scale of dispersal is an order of magnitude less than previous estimates—the median dispersal distance is just 1.7 km and no dispersal events exceed 16.4 km despite intensive sampling out to 30 km from source. Overlaid on this strong pattern is subtle spatial variation, but neither pelagic larval duration nor direction is associated with the probability of successful dispersal. Given the strong relationship between distance and dispersal, we show that distance-driven logistic models have strong power to predict dispersal probabilities. Moreover, connectivity matrices generated from these models are congruent with empirical estimates of spatial genetic structure, suggesting that the pattern of dispersal we uncovered reflects long-term patterns of gene flow. These results challenge assumptions regarding the spatial scale and presumed predictors of marine population connectivity. We conclude that if marine reserve networks aim to connect whole communities of fishes and conserve biodiversity broadly, then reserves that are close in space (<10 km) will accommodate those members of the community that are short-distance dispersers.We thank Diana Acosta, Alben David, Kevin David, Alissa Rickborn, and Derek Scolaro for assistance with field work; Eliana Bondra for assistance with molecular work; and Peter Carlson for assistance with otolith work. We are grateful to Noel Anderson, David Lindo, Claire Paris, Robert Warner, Colleen Webb, and two anonymous reviewers for comments on this manuscript. This work was supported by National Science Foundation (NSF) Grant OCE-1260424, and C.C.D. was supported by NSF Graduate Research Fellowship DGE-1247312. All work was approved by Belize Fisheries and Boston University Institutional Animal Care and Use Committee. (OCE-1260424 - National Science Foundation (NSF); DGE-1247312 - NSF Graduate Research Fellowship)Published versio
Schwarzschild models of the Sculptor dSph galaxy
We have developed a spherically symmetric dynamical model of a dwarf
spheroidal galaxy using the Schwarzschild method. This type of modelling yields
constraints both on the total mass distribution (e.g. enclosed mass and scale
radius) as well as on the orbital structure of the system modelled (e.g.
velocity anisotropy). Therefore not only can we derive the dark matter content
of these systems, but also explore possible formation scenarios. Here we
present preliminary results for the Sculptor dSph. We find that the mass of
Sculptor within 1kpc is 8.5\times10^(7\pm0.05) M\odot, its anisotropy profile
is tangentially biased and slightly more isotropic near the center. For an NFW
profile, the preferred concentration (~15) is compatible with cosmological
models. Very cuspy density profiles (steeper than NFW) are strongly disfavoured
for Sculptor.Comment: 2 pages, 4 figures, to appear in the proceedings of "Assembling the
Puzzle of the Milky Way", Le Grand Bornand (Apr. 17-22, 2011
Directed diffusion of reconstituting dimers
We discuss dynamical aspects of an asymmetric version of assisted diffusion
of hard core particles on a ring studied by G. I. Menon {\it et al.} in J. Stat
Phys. {\bf 86}, 1237 (1997). The asymmetry brings in phenomena like kinematic
waves and effects of the Kardar-Parisi-Zhang nonlinearity, which combine with
the feature of strongly broken ergodicity, a characteristic of the model. A
central role is played by a single nonlocal invariant, the irreducible string,
whose interplay with the driven motion of reconstituting dimers, arising from
the assisted hopping, determines the asymptotic dynamics and scaling regimes.
These are investigated both analytically and numerically through
sector-dependent mappings to the asymmetric simple exclusion process.Comment: 10 pages, 6 figures. Slight corrections, one added reference. To
appear in J. Phys. Cond. Matt. (2007). Special issue on chemical kinetic
- …