Measurement of the Density of Base Fluids at Pressures 0.422 to 2.20 Gpa

The influence of pressure on the density of six base fluids is experimentally studied for a range of pressures from 0.422 to 2.20 GPa. An important parameter used to describe the results is the change in relative volume with change in pressure dv sub r/dp. For pressures less than the solidification pressure (p ps) a small change in pressure results in a large change in dv sub r/ps. For pressures greater than the solidification pressure (p ps) there is no change in dv sub r/dp with changing pressure. The solidification pressures of the base fluids varies considerably, as do the slopes that the experimental data assumes for p ps. A new formula is developed that describes the effect of pressure on density in terms of four constants. These constants vary for the different base fluids tested

Weak Lensing from Space I: Instrumentation and Survey Strategy

A wide field space-based imaging telescope is necessary to fully exploit the technique of observing dark matter via weak gravitational lensing. This first paper in a three part series outlines the survey strategies and relevant instrumental parameters for such a mission. As a concrete example of hardware design, we consider the proposed Supernova/Acceleration Probe (SNAP). Using SNAP engineering models, we quantify the major contributions to this telescope's Point Spread Function (PSF). These PSF contributions are relevant to any similar wide field space telescope. We further show that the PSF of SNAP or a similar telescope will be smaller than current ground-based PSFs, and more isotropic and stable over time than the PSF of the Hubble Space Telescope. We outline survey strategies for two different regimes - a ``wide'' 300 square degree survey and a ``deep'' 15 square degree survey that will accomplish various weak lensing goals including statistical studies and dark matter mapping.Comment: 25 pages, 8 figures, 1 table, replaced with Published Versio

Comparison of telemetry and pellet-group counts for determining habitat selectivity by roe deer (Capreolus capreolus) in winter

In two forest of Sweden, has been compared winter habitat use by roe deer with habitat availability from two kinds of data (telemetry and pellet group counts). No correlation was found between comparison from two techniques except for the strongly avoided habitat types. Improvement of the methods are discusssed / Dans deux habitats forestiers de Suède, a été comparée l'utilisation hivernale de l'habitat par le chevreuil à partir de 2 méthodes : le radiopistage et le comptage des fumées. Les résultats obtenus à partir de ces approches ne montrent aucune corrélation, à l'exception des habitats profondement évités. Une discussion est amorcée sur l'absence de convergence de résultats des 2 méthodes, une amélioration des méthodes utilisées est proposée