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421.
Guillermo García-Segura Mordecai-Mark Mac Low Norbert Langer 《Astrophysics and Space Science》1995,224(1-2):459-460
We follow the interaction of massive stars with their circumstellar gas over their entire life-times by combining hydrodynamic stellar evolution calculations for 35 and 60M
stars and one- and two-dimensional gas dynamical calculations for the circumstellar medium. 相似文献
422.
Resource economies and neoliberal experimentation: the reform of industry and community in rural British Columbia 总被引:1,自引:0,他引:1
This paper argues that the current literature on neoliberalism in advanced capitalist societies has concentrated primarily on urban issues, and has thus failed to see resource economies and regions as theoretically significant sites of neoliberal reform. Using research from British Columbia, Canada, we argue that resource regions are often targets of intense neoliberal experimentation. The neoliberal project in British Columbia involves an extreme shift in state policy from a strong Fordist-Keynesian programme to recent efforts to 'liberate' corporate actors from non-market social and spatial obligations (to environment, labour and community). We argue that such policy shifts have exceptional consequences in resource regions due to strong and direct state influence in corporate-resource and community-level economies. We draw several theoretical lessons from this research for the mainstream literature on neoliberal reform. 相似文献
423.
Eugene Yee Ralph M. Gailis Alexander Hill Trevor Hilderman Darwin Kiel 《Boundary-Layer Meteorology》2006,121(3):389-432
We report on measurements of the near-field dispersion of contaminant plumes in a large array of building-like obstacles at three scales; namely, at full-scale in a field experiment, at 1:50 scale in a wind-tunnel simulation, and at 1:205 scale in a water-channel simulation. Plume concentration statistics extracted from the physical modelling in the wind-tunnel and water-channel simulations are compared to those obtained from a field experiment. The modification of the detailed structure of the plume as it interacts with the obstacles is investigated. To this purpose, measurements of the evolution of the mean concentration, concentration fluctuation intensity, concentration probability density function, and integral time scale of concentration fluctuations in the array plume obtained from the field experiment and the scaled wind-tunnel and water-channel experiments are reported and compared, as well as measurements of upwind and within-array velocity spectra. Generally, the wind-tunnel and water-channel results on the modification of the detailed plume structure by the obstacles were qualitatively similar to those observed in the field experiments. However, with the appropriate scaling, the water-channel simulations were able to reproduce quantitatively the results of the full-scale field experiments better than the wind-tunnel simulations. 相似文献
424.
The dynamics of near-surface streak formation in the neutrallystratified, rotating planetary boundary layer areinvestigated. The purpose of this note is to compare large-eddysimulation results to theoretical predictions suggesting thatstreaks are associated with non-normal mode optimal perturbations.Streaks are regions near the surface of alternating high and lowspeed fluid organized into nearly linear bands, with horizontalspacing of several hundred metres, oriented up to 30° relativeto the geostrophic wind, that evolve through a continuous cycle ofgeneration, growth, decay and reformation. We find that the earlystages of streak formation and growth are consistent with thelinear theory. 相似文献
425.
We consider star models consisting of spin 0 particles interacting only gravitationally, e.g. Higgs-particles as possible
dark matter objects. The particle gas of finite temperature is treated according to the Bose-Einstein-statistics in its non-
relativistic limit; then the use of Newtonian gravity is sufficient too. The limits of these restrictions are estimated. The
local temperature is determined with the use of energy conservation. The mass-radius relation of the objects and their further
behaviours as Bose-Einstein-condensation in the outer regions are calculated. We find strong similarities with the features
of white dwarfs and neutron stars.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
426.
Ralph S. Sutherland 《Monthly notices of the Royal Astronomical Society》1998,300(2):321-330
New calculations of free–free transition matrix element integrals are performed using modern symbolic computing techniques to evaluate the hypergeometric functions with complex arguments. The results are presented in both graphical and tabular form including accurate extrapolation methods. The results are accurate to the level of ∼ 10−4 , beyond which relativistic corrections would be needed, which are not included. The results are also computed over a very wide range of scaled ionic temperature (γ2 ) and wavelength, extending earlier results to new regimes encountered in highly photoionized and non-equilibrium ionization plasmas. These results will be useful in the spectral range from submillimetre to hard X-ray wavelengths and temperatures from 10 to 109 K. 相似文献
427.
The classic black hole candidate Cygnus X-1 exhibits many similarities to Galactic jet sources (micro-quasars) in soft gamma and hard X-ray rays. This has fuelled suspicions that radio jets also may be present in Cygnus X-1. The lack of radio flaring in Cygnus X-1 has been associated with the presence of continuous jets rather than multiple plasmon ejection however no evidence for this has been observed with the VLA, or with MERLIN. Recent VLBA observations at 15 GHz have detected extended emission and further multi frequency observations are required to confirm the presence of jets on a milliarcsecond level. 相似文献
428.
Ehrhard Raschke Ute Karstens Ralph Nolte-Holube Rüdiger Brandt Hans-Jörg Isemer Dag Lohmann Manfred Lobmeyr Burkhardt Rockel Rolf Stuhlmann 《Surveys in Geophysics》1998,19(1):1-22
The mechanisms responsible for the transfer of energy and water within the climate system are under worldwide investigation within the framework of the Global Energy and Water Cycle Experiment (GEWEX) to improve the predictability of natural and man-made climate changes at short and long ranges and their impact on water resources. Five continental-scale experiments have been established within GEWEX to enable a more complete coupling between atmospheric and hydrological models. One of them is the Baltic Sea Experiment (BALTEX).In this paper, the goals and structure of BALTEX are outlined. A short overview of measuring and modelling strategies is given. Atmospheric and hydrological model results of the authors only are presented. These include also the validation of precipitation using station measurements as well as validation of modelled cloud cover with cloud estimates from satellite data. Furthermore, results of a large-scale grid based hydrological model to be coupled to atmospheric models are presented.This research has never been possible without the contribution of research groups and operational institutions from all 10 member countries. We concentrate here on results obtained at the GKSS research center. 相似文献
429.
430.
Dr. Ralph Jaetzold 《GeoJournal》1978,2(3):225-242
Kenya is one of those African countries with a very high population pressure. In cultivatable areas we find up to 650 rural inhabitants per sq km. The search for new possibilities of agricultural settlement is an indispensable task. Many sciences are involved, also the geography of climates. Probably the largest potential settlement area from the climatic point of view is the Northern coastal zone. It has been settled in medieval times much more densely than today. War-like invasions of nomads have decreased the population since the 16th century. The average density of the cultivatable strip has been less than 5 inhabitants per sqkm in the last census year 1969. New settlement schemes have been developed since 1970, but they face the difficulty to choose the right varieties of crops. Careful climatic investigations are necessary for the further selection of areas and for the agricultural extension service. Here, only a first approach has been made. The main emphasis was laid on the effective rainfall in the so-called agrohumid period of the year and its probability. A new system of climatic classification was applied to give a frame for further, more specialised studies. 相似文献