排序方式： 共有35条查询结果，搜索用时 578 毫秒
1.
2.
3.
Melchiorri A Ade PA de Bernardis P Bock JJ Borrill J Boscaleri A Crill BP De Troia G Farese P Ferreira PG Ganga K de Gasperis G Giacometti M Hristov VV Jaffe AH Lange AE Masi S Mauskopf PD Miglio L Netterfield CB Pascale E Piacentini F Romeo G Ruhl JE Vittorio N 《The Astrophysical journal》2000,536(2):L63-L66
We use the angular power spectrum of the cosmic microwave background, measured during the North American test flight of the Boomerang experiment, to constrain the geometry of the universe. Within the class of cold dark matter models, we find that the overall fractional energy density of the universe Omega is constrained to be 0.85相似文献
4.
5.
A rigorous solution is developed from first principles to guide the preliminary design of cutoff walls installed to contain the migration of contaminants from source zones. The full analytic solution is used to develop a criterion for determining the configuration and hydraulics of optimal wall designs. The solution is used to demonstrate the interaction between the properties of the wall, the Darcy flux, and the concentration of contaminants at the outside face of the well. For a particular wall design, the containment criterion can be used to estimate the long-term concentration that will develop at the outside face of the wall. Alternatively, for a given concentration on the outside face of the cutoff wall, the containment criterion can be used to estimate the Darcy flux required to balance the outward diffusion of contaminants. The results of numerical simulations are presented to evaluate the analytic approach. The numerical results confirm that for a wall with known transport properties, a specified Darcy flux is associated with a unique outside contaminant concentration. 相似文献
7.
Pereira E Abreu SN Coelho JP Lopes CB Pardal MA Vale C Duarte AC 《Marine pollution bulletin》2006,52(11):1450-1457
The main objective was to study the seasonal variation of mercury concentrations in different tissues (muscle, hepatopancreas and gills) of Carcinus maenas from low and high Hg contaminated areas, a valuable resource in temperate estuaries and a possible pathway for human uptake. Individuals of two size classes (around 35 and 55 mm cephalothorax wide) were captured monthly between March 1999 and May 2000 in two areas of Ria de Aveiro: in the main navigation channel that connects the lagoon to the sea, and in the inner lagoon area heavily contaminated by mercury (maximum Hg in sediments of 5.4 microg g(-1)). Pronounced decreases in salinity and temperature and reduced food availability in winter seemed to be the responsible for the decline of the crab condition index (0.75-0.45) in larger individuals. Muscle and hepatopancreas exhibited higher mercury concentrations than gills, with concentrations in the contaminated site ranging from 0.03 to 0.63 microg g(-1) and 0.02 to 0.34 microg g(-1), respectively. Linear regressions between muscle and hepatopancreas (r=0.94, p<0.001) and muscle and gills (r=0.97, p<0.001) suggested a rapid redistribution of mercury inside the organism. During winter, a rapid elimination of mercury was found in the three analysed tissues followed by uptake. Larger crabs presented elimination rates from 18 to 34 ng g(-1) per week, while the smaller crabs showed lower elimination rates (10-24 ng g(-1) per week). The uptake was similar in both size classes (11-15 ng g(-1) and 8.1-15 ng g(-1) per week, respectively for large and small crabs). Our results suggest that C. maenas harvested in the contaminated areas must be considered with caution, since Hg concentrations were found to exceed the threshold concentration allowed for human consumption (0.5 microg g(-1)). 相似文献
8.
9.
10.
Mauskopf PD Ade PA de Bernardis P Bock JJ Borrill J Boscaleri A Crill BP DeGasperis G De Troia G Farese P Ferreira PG Ganga K Giacometti M Hanany S Hristov VV Iacoangeli A Jaffe AH Lange AE Lee AT Masi S Melchiorri A Melchiorri F Miglio L Montroy T Netterfield CB Pascale E Piacentini F Richards PL Romeo G Ruhl JE Scannapieco E Scaramuzzi F Stompor R Vittorio N 《The Astrophysical journal》2000,536(2):L59-L62
We describe a measurement of the angular power spectrum of anisotropies in the cosmic microwave background (CMB) at scales of 0&fdg;3 to 5 degrees from the North American test flight of the Boomerang experiment. Boomerang is a balloon-borne telescope with a bolometric receiver designed to map CMB anisotropies on a long-duration balloon flight. During a 6 hr test flight of a prototype system in 1997, we mapped more than 200 deg(2) at high Galactic latitudes in two bands centered at 90 and 150 GHz with a resolution of 26&arcmin; and 16&farcm;5 FWHM, respectively. Analysis of the maps gives a power spectrum with a peak at angular scales of 1 degrees with an amplitude 70 μK(CMB). 相似文献