974 research outputs found
Properties of the Soliton-Lattice State in Double-Layer Quantum Hall Systems
Application of a sufficiently strong parallel magnetic field produces a soliton-lattice (SL) ground state in a double-layer quantum
Hall system. We calculate the ground-state properties of the SL state as a
function of for total filling factor , and obtain the
total energy, anisotropic SL stiffness, Kosterlitz-Thouless melting
temperature, and SL magnetization. The SL magnetization might be experimentally
measurable, and the magnetic susceptibility diverges as .Comment: 4 pages LaTeX, 1 EPS figure. Proceedings of the 12th International
Conference on the Electronic Properties of Two-Dimensional Electron Systems
(EP2DS-12), to be published in Physica B (1998
Modeling energy and reproductive costs in caribou exposed to low flying military jet aircraft
We used simulation modeling to estimate the effect of low-flying military jet aircraft on the productivity of caribou. The base model (CARIBOU, CWS Whitehorse, Yukon Territory) uses daily intake and expenditure of energy to assess the condition of female caribou throughout the annual cycle. The activity budget of the model caribou was adjusted based on field observations of responses to noise disturbance. A subroutine was added that predicted the likelihood of conception based on fall body fat weight. Caribou responses to overflights were evaluated by equipping free-ranging caribou with radio collars and activity sensors that could distinguish between resting and active periods. Collared animals were exposed to 110 overflights by A-10, F-15 and F- 16 jet aircraft during late-winter, post-calving and the insect season. Noise exposure levels for individual animals either were measured directly with collar-mounted dosimeters or were estimated based on the proximity of the caribou to the aircraft during the overflight. A Time-averaged Sound Level (LT) was calculated from the total daily noise exposure for each animal and linear regression was used to evaluate the influence of daily noise exposure on daily hours spent resting. Results of these analyses then were used to modify the time budgets in the CARIBOU model. That is, if time spent resting declined, then time spent in the two rest classes (lying and standing) were proportionately redistributed into the three active classes (foraging, walking and running). Model simulations indicated that caribou increased forage intake in response to increased noise exposure, but it also predicted that increased noise exposure would cause a reduced accumulation of body fat. Because body fat in fall has successfully been used to predict the probability of pregnancy (see Gerhart et al, 1993), this relationship was used in the model. Preliminary model simulations indicate that increased noise exposure decreases the probability of pregnancy and that unfavorable environmental conditions (e.g., deep snow and severe insect harassment) exacerbate the situation. The threshold at which point the caribou fail to conceive has not been determined at this time, but appears to be well beyond the exposure to aircraft that caribou in the Delta herd are currently experiencing
Astrophysical Probes of Fundamental Physics
I review the theoretical motivation for varying fundamental couplings and
discuss how these measurements can be used to constrain a number of fundamental
physics scenarios that would otherwise be inacessible to experiment. As a case
study I will focus on the relation between varying couplings and dark energy,
and explain how varying coupling measurements can be used to probe the nature
of dark energy, with important advantages over the standard methods. Assuming
that the current observational evidence for varying and is
correct, a several-sigma detection of dynamical dark energy is feasible within
a few years, using currently operational ground-based facilities. With
forthcoming instruments like CODEX, a high-accuracy reconstruction of the
equation of state may be possible all the way up to redshift .Comment: Invited Review talk at the ESO Precision Spectroscopy in Astrophysics
conference, to appear in the proceeding
Using the opinions of coronary heart disease patients in designing a health education booklet for use in general practice consultations
Identifying strategies to maximise recruitment and retention of practices and patients in a multicentre randomised controlled trial of an intervention to optimise secondary prevention for coronary heart disease in primary care.
Interventions outside the workplace for reducing sedentary behaviour in adults under 60
This is a protocol for a Cochrane Review (Intervention). The objectives are as follows: To assess the effects of non-occupational interventions for reducing sedentary behaviour in adults under 60 years of age on sedentary time. Secondary objectives are: to describe other health effects, and adverse events or unintended consequences of the interventions; to determine whether specific components of interventions are associated with changes in sedentary behaviour; to examine if there are any differential effects of interventions based on health inequalities (e.g. age, sex, income, employment)
Isospin Response of the 4-He Continuum
This research was sponsored by the National Science Foundation Grant NSF PHY 87-1440
The cost-effectiveness of the SPHERE intervention for the secondary prevention of coronary heart disease
Effect of tailored practice and patient care plans on secondary prevention of heart disease in general practice: cluster randomised controlled trial
Objective To test the effectiveness of a complex intervention designed, within a theoretical framework, to improve outcomes for patients with coronary heart disease
Transverse emittance measurements on an S-band photoinjector rf electron gun
Proposed fourth generation light sources using SASE FELs to generate short
pulse, coherent, X-rays require demonstration of high brightness electron
sources. The Gun Test Facility (GTF) at SLAC was built to test high brightness
sources for the proposed Linac Coherent Light Source at SLAC. The transverse
emittance measurements are made at nearly 30 MeV by measuring the spot size on
a YAG screen using the quadrupole scan technique. The emittance was measured to
vary from 1 to 3.5 mm-mrad as the charge is increased from 50 to 350 pC using a
laser pulse width of 2 ps FWHM. The measurements are in good agreement with
simulation results using the LANL version of PARMELA.Comment: 12 pages, 4 figures, contributed to The 23rd Int. FEL Conf.,
Darmstadt, 20-24 Aug. 200
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