61 research outputs found
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
On extended thermonuclear functions through pathway model
The major problem in the cosmological nucleosynthesis is the evaluation of
the reaction rate. The present scenario is that the standard thermonuclear
function in the Maxwell-Boltzmann form is evaluated by using various
techniques. The Maxwell-Boltzmannian approach to nuclear reaction rate theory
is extended to cover Tsallis statistics (Tsallis, 1988) and more general cases
of distribution functions. The main purpose of this paper is to investigate in
some more detail the extended reaction probability integral in the equilibrium
thermodynamic argument and in the cut-off case. The extended reaction
probability integrals will be evaluated in closed form for all convenient
values of the parameter by means of residue calculus. A comparison of the
standard reaction probability integrals with the extended reaction probability
integrals is also done.Comment: 21 pages, LaTe
Omnidispersible poly(ionic liquid)-functionalized cellulose nanofibrils : surface grafting and polymer membrane reinforcement
The Cosmic-Ray Proton and Helium Spectra measured with the CAPRICE98 balloon experiment
A new measurement of the primary cosmic-ray proton and helium fluxes from 3
to 350 GeV was carried out by the balloon-borne CAPRICE experiment in 1998.
This experimental setup combines different detector techniques and has
excellent particle discrimination capabilities allowing clear particle
identification. Our experiment has the capability to determine accurately
detector selection efficiencies and systematic errors associated with them.
Furthermore, it can check for the first time the energy determined by the
magnet spectrometer by using the Cherenkov angle measured by the RICH detector
well above 20 GeV/n. The analysis of the primary proton and helium components
is described here and the results are compared with other recent measurements
using other magnet spectrometers. The observed energy spectra at the top of the
atmosphere can be represented by (1.27+-0.09)x10^4 E^(-2.75+-0.02) particles
(m^2 GeV sr s)^-1, where E is the kinetic energy, for protons between 20 and
350 GeV and (4.8+-0.8)x10^2 E^(-2.67+-0.06) particles (m^2 GeV nucleon^-1 sr
s)^-1, where E is the kinetic energy per nucleon, for helium nuclei between 15
and 150 GeV nucleon^-1.Comment: To be published on Astroparticle Physics (44 pages, 13 figures, 5
tables
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
Secondary organic aerosol reduced by mixture of atmospheric vapours
Secondary organic aerosol contributes to the atmospheric particle burden with implications for air quality and climate. Biogenic volatile organic compounds such as terpenoids emitted from plants are important secondary organic aerosol precursors with isoprene dominating the emissions of biogenic volatile organic compounds globally. However, the particle mass from isoprene oxidation is generally modest compared to that of other terpenoids. Here we show that isoprene, carbon monoxide and methane can each suppress the instantaneous mass and the overall mass yield derived from monoterpenes in mixtures of atmospheric vapours. We find that isoprene 'scavenges' hydroxyl radicals, preventing their reaction with monoterpenes, and the resulting isoprene peroxy radicals scavenge highly oxygenated monoterpene products. These effects reduce the yield of low-volatility products that would otherwise form secondary organic aerosol. Global model calculations indicate that oxidant and product scavenging can operate effectively in the real atmosphere. Thus highly reactive compounds (such as isoprene) that produce a modest amount of aerosol are not necessarily net producers of secondary organic particle mass and their oxidation in mixtures of atmospheric vapours can suppress both particle number and mass of secondary organic aerosol. We suggest that formation mechanisms of secondary organic aerosol in the atmosphere need to be considered more realistically, accounting for mechanistic interactions between the products of oxidizing precursor molecules (as is recognized to be necessary when modelling ozone production).Peer reviewe
Quantitative profiling of oxylipins through comprehensive LC-MS/MS analysis: application in cardiac surgery
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
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