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801.
Mary K. Wicksten 《Marine pollution bulletin》1984,15(1):28-33
Sea anemones (Anthopleura elegantissima) can withstand submersion in Bunker C fuel oil for up to 1 h without visible adverse effects. The wet, mucus-covered tissues of the sea anemones may repel oil. During recovery, the sea anemones expand the column, evert the tentacles and reattach. A dahlia anemone (Tealia lofotensis) withstood immersion in oil for 15 min. The ability to withstand immersion in oil may confer an ecological advantage to sea anemones in contaminated areas. 相似文献
802.
803.
804.
Analysis of wind profiles at the Boulder Tower (BAO) leads to these conclusions:
- The variation of roughness with wind direction found earlier is confirmed. Roughness lengths measured on the tower are larger than those measured close to the surface.
- The profiles and measurements of Reynolds stress are consistent with a von-Karman constant of 0.35.
- The form φm=(1?15z/L)-1/3 fits best in the range -0.6 < z/L < 0. In the range 0 < z/L < 0.5, θ m ~ 1 + 4.7z/L provides a good fit to the observations. For z/L < 0.1, φ m also depends on h, the thickness of the PBL. For z/L < -0.6, Φ m approaches the constant 0.5, in contrast to all previous suggestions. For larger stabilities, the upper level is usually not in the surface layer, and wind ratios become independent of z/L.
- With snow cover, the effective roughness diminishes to about 1 cm, even for directions for which the roughness length without snow is large.
- Estimation of winds at 100 or 150 m from information near the surface is best for similarity theory provided that the ratio of height to Monin-Obukhov L is less than 0.1. For larger z/L, simple power laws seem more appropriate.
805.
Evaporite dissolution and development of karst features on the rolling plains of the texas panhandle
More than 400 dolines, consisting of collapse sinkholes and closed depressions, occur in Hall and Briscoe Counties, Texas. Of these, at least 36 sinkholes and two depressions formed between 1940 and 1972. Collapse sinks are typically circular and range up to 100 m in diameter and 15 m in depth. Closed depressions are irregularly-shaped, internally-drained depressions up to 2.4 km in length. Surface fractures up to 1.5 km in length are associated with certain closed depressions. Karst features are forming as a result of intrastratal dissolution of Upper Permian evaporites, primarily halite and secondarily gypsum. Salt dissolution and overburden collapse are evident from geophysical log cross-sections and occur at depths ranging from 195 to 275 m. Dissolution is progressing down dip and mean dissolution rates for salt beds in the Hall County area range from 0.29 to 7.73 cm/yr. The valley of the Prairie Dog Town Fork of the Red River is an area of ground-water discharge for flow systems moving eastward from topographically high areas of the Rolling Plains and from the eastern rim of the High Plains. Halite beds in contact with these waters undergo dissolution. Salt springs and brine seeps, some associated with sinkholes and depressions, occur in the discharge area and indicate that dissolution is an ongoing process. 相似文献
806.
807.
Ann Savage 《Astrophysics and Space Science》1986,119(1):233-237
Several optical techniques are being used to find quasars using UKST direct and objective prism plates. Six already much-studied fields are proposed as standard fields for the comparison of techniques. The completeness of objective prism samples, and their applicability to studies of three-dimensional quasar clustering, are discussed.Paper presented at the IAU Third Asian-Pacific Regional Meeting, held in Kyoto, Japan, between 30 September–6 October, 1984. 相似文献
808.
Mortar Upscaling for Multiphase Flow in Porous Media 总被引:1,自引:0,他引:1
In mortar space upscaling methods, a reservoir is decomposed into a series of subdomains (blocks) in which independently constructed numerical grids and possibly different physical models and discretization techniques can be employed in each block. Physically meaningful matching conditions are imposed on block interfaces in a numerically stable and accurate way using mortar finite element spaces. Coarse mortar grids and fine subdomain grids provide two-scale approximations. In the resulting effective solution flow is computed in subdomains on the fine scale while fluxes are matched on the coarse scale. In addition the flexibility to vary adaptively the number of interface degrees of freedom leads to more accurate multiscale approximations. This methodology has been implemented in the Center for Subsurface Modeling's multiphysics multiblock simulator IPARS (Integrated Parallel Accurate reservoir Simulator). Computational experiments demonstrate that this approach is scalable in parallel and it can be applied to non-matching grids across the interface, multinumerics and multiphysics models, and mortar adaptivity. Moreover unlike most upscaling approaches the underlying systems can be treated fully implicitly. 相似文献
809.
Coves near an ocean inlet in Little Egg Harbor in southern New Jersey may be important settlement areas for winter flounder (Pseudopleuronectes americanus), based on the high abundance of small postlarval individuals. During 1994–1996 we sampled in two coves and adjacent areas of this same estuary to determine if this pattern was annually consistent. Collections in spring and early summer indicated that small, recently-settled winter flounder (10–45 mm TL) were abundant in the coves from May to mid-June in every year with maximum mean densities ranging from 1.5–2.5 ind m−2 and that these same size individuals were never collected at these densities in other habitats in the same estuary. Densities in the coves declined soon after settlement, usually by late June to early July in each year. In order to determine factors that may influence these high settlement rates we examined aspects of habitat quality by determining habitat-specific growth rates in cages for recently-settled individuals (17.5–38.3 mm TL) both inside and outside the coves during 1995. These rates (3.7–9.1 wt d−1) overlapped those of other estuarine habitats (3.1–10.5 wt d−1) suggesting that habitat quality, based on growth, does not differentiate the coves from other potential settlement habitats. Mark/recapture experiments for recently settled individuals (range 13–70 mm TL) in 1994 and 1996 had low recapture rates (1% in both years) suggesting that dispersal from the cove occurred soon after settlement. This pattern confirms that these coves are used as settlement areas but they are probably not used as nurseries because winter flounder, at least in this system, do not settle and stay and, as a result, use other habitats as primary nursery areas. 相似文献
810.
We assessed the presence and quantified the intracellular virus-like particles (VLPs) in natural populations ofAureococcus anophagefferens during the 1999–2000 brown tide blooms that occurred in New Jersey coastal waters. From displayed a wide range of ultrastructural changes from apparently healthy cells to those showing late stages of production of VLPs. VLP-infected cells usually had an electron dense plasma membrane and lacked the typical exocellular polysaccharide layer (EPS). The VLPs were similar in size (c. 140 nm) and morphology to those initially reported in natural populations ofA. anophagefferens and to brown tide viruses (BtVs) which were previously isolated and inoculated into laboratory cultures ofA. anophagefferens. VLP-infectedA. anophagefferens were found consistently throughout the brown tide blooms in both years in Little Egg Harbor. Percentages of VLP-infected cells were 8.1% at the beginning of a bloom, which decreased to less than 2% at the height of the blooms during both years, and increased at the end of the 2000 bloom to 2.5%. While these percentages appear low, the estimated VLP infection rate ofA. anophagefferens cells, which ranged from 0.83%–50% of the standing population, is comparable to other studies. 相似文献