نتایج جستجو برای: planetary atmosphere
تعداد نتایج: 74273 فیلتر نتایج به سال:
Hydrostatic pressures of 500 to 700 atmospheres have been shown to accelerate the observed rate of certain processes both in living cells, e.g. the light-emitting oxidation of luminous bacteria, and in crude enzyme preparations at temperatures higher than the normal optimum.’ The present study provides exploratory data concerning the activity of a crystallized enzyme preparation, trypsin, in re...
Determining the internal kinematics of a galaxy from planetary nebulae (PN) is usually a two step process in which the candidate PN are first identified in a target galaxy and then, in a follow up run, spectra are obtained. We have implemented a new technique in which two dispersed images at the wavelength of the [O III] emission line at 5007Å are combined to yield positions, magnitudes and vel...
Twenty-seven isolates of Penicillium expansum Lk. ex Thom obtained from Europe, Australia, and North America from seven different fruit hosts all produced patulin in culture. Six isolates were essentially nonpathogenic in apple fruits. In culture, patulin generally accumulated to much higher levels than in apple fruits. At all temperatures permitting fungus growth, patulin was produced. However...
The energy required to form and remove vacancies on metal surfaces mediates the rate of mass transport during a wide range of processes. These energies are known to be sensitive to environmental conditions. Here, we use electronic structure density functional theory calculations to show that the surface vacancy formation energy of silver changes markedly in the presence of adsorbed and dissolve...
Stars with masses ranging from 7 to 10 times the mass of the Sun end their lives either as massive white dwarfs or weak type II supernovae, but there are only limited observational constraints on either evolutionary channel. Here we report the detection of two white dwarfs with large photospheric oxygen abundances, implying that they are bare oxygen-neon cores and that they may have descended f...
This paper gives the technical characteristics of the Italian Committee for Research and Development of Nuclear Energy and Alternative Energy (ENEA) radon chamber and the operational procedures developed for testing radon and daughters measuring equipment. Runs were carried out under different experimental conditions defined in terms of radon and daughter concentrations, equilibrium ratio (F-fa...
The slope method has customarily been used and is still used for inversion of atmospheric optical parameters, extinction, and backscatter in homogeneous atmospheres from lidar returns. Our aim is to study the underlying statistics of the old slope method and ultimately to compare its inversion performance with that of the present-day nonlinear least-squares solution (the so-called exponential-c...
Chandra’s high angular resolution can resolve emission from stellar X-ray binaries out of the diffuse X-ray emission from gaseous atmospheres within elliptical galaxies. Variations in the X-ray binary populations (per unit galaxian optical luminosity) are correlated with variations in the specific frequency of globular clusters in ellipticals. This indicates that X-ray binaries are largely form...
Through a simple physical argument we show that the slant optical depth through the atmosphere of a ‘hot Jupiter’ planet is ∼ 35-90 times greater than the normal optical depth. This not unexpected result has direct consequences for the method of transmission spectroscopy for characterizing the atmospheres of transiting giant planets. The atmospheres of these planets likely contain minor condens...
The use of calorimetry as a tool to understand the effects of controlled atmospheres (CA) on insects is briefly reviewed. A variety of data are presented to illustrate the various types of information that calorimetry can make available to researchers. The use of a calorimeter connected to a mass spectrometer to determine the occurrence of anaerobic respiration is described and reported. We con...
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