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281.
Francisco E. Werner John A. Quinlan Brian O. Blanton Richard A. Luettich Jr. 《Journal of Sea Research》1997,37(3-4)
A review of the physical processes present in coastal regions and their effect on pelagic stages of flatfish populations is presented. While quantitative understanding of processes affecting cross-shelf transport and exchange continues to be a fundamental problem shared by physical oceanographers and fisheries scientists studying the early life history of flatfish, advances in hydrodynamic and coupled physical-biological models have made it possible to begin to examine population-level implications of environmental processes. There is now a need to rank these processes in terms of their impact on recruit strength. Existing paradigms provide testable frameworks for explaining the role of physical variability in the observed population patterns, abundance and variability. Identifying explicit links between physical variability and recruitment could result in new approaches to fisheries management strategies. 相似文献
282.
Side-scan sonar and sub-bottom profiling investigations of the Iceland-Faeroe Ridge have revealed the widespread presence
of iceberg plowmarks at water depths between 750 and 860 m. This is well beyond the maximum water depth reported for ice scouring
in the adjacent areas of the North Atlantic. An exceptionally deep iceberg plowmark was found at the southern flank of the
ridge, which could be traced down to 940 m water depth. Supported by published nearby sediment core data, a Saalian (MIS 6)
age of that iceberg plowmark is suggested. Considering a glacial sea level of 120 m below present, the paleo-draft of this
iceberg is estimated to have been at least 820 m. The keel depth of such giant icebergs drifting in the glacial northern North
Atlantic significantly exceeds the draft dimensions of large icebergs seen today in the Antarctic. The most likely source
area for this extreme deep-draft type of iceberg is inferred to be southern Greenland. Plowmark direction, which in our case
indicates iceberg entrainment by the North Atlantic Current, is suggested to be a useful indicator of (sub)surface paleo-circulation
during late Pleistocene iceberg surging and deglaciation episodes. 相似文献
283.
Reasons for Spatial Microdistributions of Foraminifers in an Intertidal Pool (Northern Adriatic Sea)
Abstract. The spatial microdistribution of foraminifers was tested by the method of quadratic samplings on 2 sample grids in an intertidal pool of the northernmost Adriatic sea. Abundant species of foraminifers exhibit patchy distributions throughout; the distribution-patterns of some species correspond nearly completely. Using statistical methods (regression- and correlation-analyses) correlations to abiotic and biotic factors (water depth, exposure rate, seagrass, benthonic algae) were ascertained. The significant correlations of the foraminiferal frequencies to blue-green algae and/or diatoms enable an interpretation of these connexions as food dependences. Several foraminiferal species seem to have specific diets. 相似文献
284.
H. M. Butner G. H. Moriarty-Schieven M. E. Ressler M. W. Werner 《Astrophysics and Space Science》1995,231(1-2):77-80
The exotic quantum process of photon splitting has great potential to explain the softness of emission in soft gamma repeaters (SGRs) if they originate in neutron stars with surface fields above the quantum critical fieldB
cr = 4.413×1013 Gauss. Splitting becomes prolific at such field strengths: its principal effect is to degrade photon energies, initiating a cascade that softens gamma-ray spectra. Uniform field cascade calculations have demonstrated that emission could be softened to the observed SGR energies for fields exceeding about 1014 Gauss. Recently, we have determined splitting attenuation lengths and maximum energies for photon escape in neutron star environments including the effects of magnetospheric dipole field geometry. Such escape energies esc suitably approximate the peak energy of the emergent spectrum, and in this paper we present results for
esc as a function of photon emission angles for polar cap and equatorial emission regions. The escape energy is extremely insensitive to viewing perspective for equatorial emission, arguing in favour of such a site for the origin of SGR activity. 相似文献
285.
Effects of dietary exposure to the pyrethroid pesticide esfenvalerate on medaka (Oryzias latipes) 总被引:3,自引:0,他引:3
Werner I Geist J Okihiro M Rosenkranz P Hinton DE 《Marine environmental research》2002,54(3-5):609-614
The pyrethroid insecticide esfenvalerate is widely used on orchard crops throughout California. In the aquatic environment, this compound is likely to accumulate in sediments, food particles and benthic organisms due to its lipophilicity and environmental persistence. This pilot project tested the hypothesis that esfenvalerate is toxic to medaka (Oryzias latipes) when taken up with the diet. For 7 days fish were fed diets, which contained esfenvalerate in three different concentrations (4, 21, 148 mg/kg, measured). Endpoints measured were mortality, fecundity, fertilization and hatching success of embryos, viability of larvae and cellular stress protein (hsp60, hsp70, hsp90) levels. The toxicity of aqueous exposure of medaka to esfenvalerate was also determined. Whereas the 96-h LC50 in the aqueous exposure was <9.4 microg/l, the dietary exposure did not cause mortality. Possible effects of dietary esfenvalerate were seen on fertilization and hatching success and the number of non-viable larvae. Expression of hsp60 and hsp90 showed a dose-dependent response pattern. 相似文献
286.
Werner Borchert 《Contributions to Mineralogy and Petrology》1948,1(4):394-398
Ohne ZusammenfassungAuszug aus der gleichbetitelten Arbeit in der unveröffentlichten Festschrift zum 70jährigen Geburtstag von Herrn Professor Dr.O. H. Erdmannsdörffer. 相似文献
287.
288.
Ohne Zusammenfassung 相似文献
289.
Werner Schwan 《International Journal of Earth Sciences》1949,37(1):51-60
Ohne Zusammenfassung 相似文献
290.