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561.
R.L. Davis 《大气与海洋》2013,51(2):169-176
Abstract A topoclimatic classification was developed to map the frequency of damaging spring radiation frosts to six deciduous fruit varieties at a scale of 1:25,000. The methodology utilizes night‐time temperatures from climatological stations operated by the Atmospheric Environment Service (aes) ofEnvironment Canada, as well as night‐time temperatures from a temporary network of standard climate stations and mobile temperature surveys. Maps of the deviation of minimum temperature from the local aes climate station, and of spring frost risk for each fruit variety are produced. 相似文献
562.
Since the late 1970s, labor-intensive forest workers in the Pacific Northwest have been mostly Latino. These workers and their Anglo counterparts plant and thin trees, perform other forestry services, and fight wildland fires. Poor job quality has been persistent, especially for Latino workers. We compare working conditions between fire suppression and nonsuppression forest work across Latino and non-Latino populations in Oregon. We find that although both groups share some similar conditions, Latino workers often faced poorer conditions, including disrespectful treatment, uncompensated injuries, risk of being blackballed if they complained, and little opportunity for advancement. However, there were some important job quality improvements for Latinos in fire suppression, including compensation for travel and training. Differences in contracting market structure and federal oversight between fire suppression and other forest work may contribute to improved job quality. This suggests the potential for improving conditions by focusing on improving contracting markets and oversight. 相似文献
563.
J. R. North J. Davis P. G. Tuthill W. J. Tango J. G. Robertson 《Monthly notices of the Royal Astronomical Society》2007,380(3):1276-1284
The first orbital solution for the spectroscopic pair in the multiple star system σ Scorpii, determined from measurements with the Sydney University Stellar Interferometer, is presented. The primary component is of β Cephei variable type and has been one of the most intensively studied examples of its class. The orbital solution, when combined with radial velocity results found in the literature, yields a distance of 174+23 −18 pc , which is consistent with, but more accurate than the Hipparcos value. For the primary component we determine 18.4 ± 5.4 M⊙ , −4.12 ± 0.34 mag and 12.7 ± 1.8 R⊙ for the mass, absolute visual magnitude and radius, respectively. A B1 dwarf spectral type and luminosity class for the secondary is proposed from the mass determination of 11.9 ± 3.1 M⊙ and the estimated system age of 10 Myr. 相似文献
564.
565.
566.
J. G. Barzyk M. R. Savina A. M. Davis R. Gallino F. Gyngard S. Amari E. Zinner M. J. Pellin R. S. Lewis R. N. Clayton 《Meteoritics & planetary science》2007,42(7-8):1103-1119
Abstract— Analyses of the isotopic compositions of multiple elements (Mo, Zr, and Ba) in individual mainstream presolar SiC grains were done by resonant ionization mass spectrometry (RIMS). While most heavy element compositions were consistent with model predictions for the slow neutron capture process (s‐process) in low‐mass (1.5–3 M⊙) asymptotic giant branch stars of solar metallicity when viewed on single‐element three‐isotope plots, grains with compositions deviating from model predictions were identified on multi‐element plots. These grains have compositions that cannot result from any neutron capture process but can be explained by contamination in some elements with solar system material. Previous work in which only one heavy element per grain was examined has been unable to identify contaminated grains. The multi‐element analyses of this study detected contaminated grains which were subsequently eliminated from consideration. The uncontaminated grains form a data set with a greatly reduced spread on the three‐isotope plots of each element measured, corresponding to a smaller range of 13C pocket efficiencies in parent AGB stars. Furthermore, due to this reduced spread, the nature of the stellar starting material, previously interpreted as having solar isotopic composition, is uncertain. The constraint on 13C pocket efficiencies in parent stars of these grains may help uncover the mechanism responsible for formation of 13C, the primary neutron source for s‐process nucleosynthesis in low‐mass stars. 相似文献
567.
The DEEP2 Galaxy Redshift Survey: the relationship between galaxy properties and environment at z∼ 1
Michael C. Cooper Jeffrey A. Newman † Darren J. Croton Benjamin J. Weiner Christopher N. A. Willmer Brian F. Gerke Darren S. Madgwick † S. M. Faber Marc Davis Alison L. Coil † Douglas P. Finkbeiner Puragra Guhathakurta David C. Koo 《Monthly notices of the Royal Astronomical Society》2006,370(1):198-212
568.
Antonio Chrysostomou Rachel Curran David Aitken Tim Jenness Chris Davis 《Astrophysics and Space Science》2003,287(1-4):161-164
We report on early results of magnetic field measurements towards a sample of young stellar objects. The results show a variety of field configurations, some of which can be explained by conventional models, while others cannot. We find that the field in some cases is curved over large scales and influenced by the gas kinematics in the local environment. This implies that, at these scales at least, the magnetic field plays a passive rôle in the star formation process. 相似文献
569.
S. Tiné D.A. Williams D.C. Clary A.J. Farebrother A.J. Fisher A.J.H.M. Meijer J.M.C. Rawlings C.J. Davis 《Astrophysics and Space Science》2003,288(3):377-389
Theoretical predictions by Farebrother et al. and Meijer et al. of rovibrational excitation probabilities in H2 arising from formation by Eley-Rideal processes on a graphite surface are incorporated into a model of the chemistry and
excitation of interstellar H2. The model includes the usual radiative and collisional pumping of H2 rotational and vibrational states, in addition to the formation processes. Predictions are made for HH2 rovibrational emission line intensities for representative points in diffuse and in dark interstellar clouds. We find that
– if all the interstellar HH2 is formed by this Eley-Rideal process – then the consequences of formation pumping, as distinct from collisional and radiative
pumping, should be clearly evident in both cases. In particular, we predict a clear spectral signature of this direct HH2 formation process on graphite, distinct from radiative and collisional pumping; this signature should be evident in both
diffuse and dark clouds; but the emissivity for dark clouds is predicted to be some 500 times greater than that in diffuse
clouds in which the dense material may be embedded. An observational search for this signature in two dark cloud sources was
made, but a preliminary analysis of the data did not yield a detection. The implications of and possible reasons for this
preliminary conclusion are discussed.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
570.