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Self-ordered polymers and propagative cell-like systems 总被引:1,自引:0,他引:1
Sidney W. Fox 《Die Naturwissenschaften》1969,56(1):1-9
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Lee P. Shulman MD Patricia L. Gordon Donald S. Emerson R. Sidney Wilroy Sherman Elias 《黑龙江环境通报》1993,13(5):403-409
We describe the prenatal diagnosis of isolated bilateral fetal microphthalmia in a woman at increased risk of having a fetus with microphthalmia. Ultrasound examinations at 161 and 19-5 weeks' gestation demonstrated bilateral fetal microphthalmia with no other associated structural defects. The patient elected to terminate her pregnancy at 19.5 weeks. Pathological evaluation of the products of conception obtained by dilation and evacuation confirmed the prenatal diagnosis of isolated bilateral fetal microphthalmia. 相似文献
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Steven N. Chillrud Richard F. Bopp James M. Ross Damon A. Chaky Sidney Hemming Edward L. Shuster H. James Simpson Frank Estabrooks 《Water, Air, & Soil Pollution: Focus》2004,4(2-3):469-482
Radionuclide, radiogenic lead isotope and trace metal analyses on fine-grained sediment cores collected along 160 km of the upper and tidal Hudson River were used to examine temporal trends of contaminant loadings and to develop radiogenic lead isotopes both as a stratigraphic tool and as tracers for resolving decadal particle transport fluxes. Very large inputs of Cd, Sb, Pb, and Cr are evident in the sediment record, potentially from a single manufacturing facility. The total range in radiogenic lead isotope ratios observed in well-dated cores collected about 24 km downstream of the plant is large (e.g., maximum difference in 206Pb/207Pb is 10%), characterized by four major shifts occurring in the 1950s, 1960s, 1970s and 1980s. The upper Hudson signals in Cd and radiogenic lead isotopes were still evident in sediments collected 160 km downstream in the tidal Hudson. The large magnitude and abrupt shifts in radiogenic lead isotope ratios as a function of depth provide sensitive temporal constraints that complement information derived from radionuclide analyses to significantly improve the precision of dating assignments. Application of a simple dilution model to data from paired cores suggests much larger sediment inputs in one section of the river than previously reported, suggesting particle influxes to the Hudson have been underestimated. 相似文献
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In other hazardous complex socio-technical systems in society, e.g. nuclear power and aviation, systems-theoretical assumptions are considered a promising way to better understand and manage safety. In this paper, two fundamental approaches to road safety were assessed in the light of a systems theory approach. One approach, is based on a premise where individual road-users are solely responsible when crashes occur. In that case countermeasures are aimed at altering the behavior of the road-user in order to adapt him/her to the road transport system. The other approach, the so-called zero-tolerance position, or Vision Zero approach, to road safety is built around two axioms; the system must be adapted to the psychological and physical conditions and limitations of the human being and the responsibility for road safety must be shared between the road-users and the designers and professional operators of the system. It was found that the most important determinants of systems theory are basically not present in the road-user approach. However, even if the Vision Zero approach clearly takes step towards systems theory, it does leave room for articulating even more features of systems theory. 相似文献
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Nicholas L. Clesceri Sidney J. Curran Richard I. Sedlak 《Journal of the American Water Resources Association》1986,22(6):983-990
ABSTRACT: Export coefficients (kg/km2/yr) for dissolved ortho-phosphate (OP), total phosphorus (TP), total inorganic nitrogen (TIN), and total nitrogen (TN) were derived for watersheds in Wisconsin using data bases available for 17 basins from the U.S. Environmental Protection Agency — National Eutrophication Survey, U.S. Geological Survey, and the Wisconsin Department of Natural Resources. Three general land use categories, representative of most regions in Wisconsin, were established: forest, mixed, and agricultural. Data for the 17 basins indicated greater exports of OP. TP, TIN, and TN as the percentage of forest decreased and agriculture increased. These region-specific coefficients are compared to the values reported in the literature representing much broader areas of the U.S. 相似文献
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Sidney C. Soderholm 《Environment international》1981,5(4-6)
Since the deposition of particulate in the respiratory system is strongly influenced by particle size, a correct assessment of this parameter is important for any inhalation experiment studying the potential health effects of air pollutants. Measuring the distribution of particles according to their aerodynamic diameter and mechanical mobility diameter is crucial in analyzing the deposition of submicron particles in the lower respiratory system. Cascade impactor measurements of diluted diesel exhaust in 12.6 m3 animal exposure chambers in the GMR Biomedical Science Department showed that the mass median aerodynamic diameter of the aerosol was 0.2 μm with 88% of the mass in particles smaller than 1 μm. Diffusion battery measurements showed that the mass median mechanical mobility diameter was about 0.11 μm. Transmission electron micrographs of particles deposited on chamber surfaces revealed both agglomerates and nearly spherical particles. The particles in these chambers are similar in size and shape to diesel particles described elsewhere. The flux of diesel particles to food surfaces was measured. Calculations of the expected daily dose by inhalation and by feeding showed that the “worst case” dose by feeding was only about one-tenth the dose by breathing. 相似文献
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Sidney W. Fox 《Die Naturwissenschaften》1980,67(12):576-581
Recent astrophysical studies suggest a high degree of order in the inanimate universe, stemming from cosmic beginnings. This state is consistent with the nonrandomness observed experimentally in the thermal polymers of amino acids that figure as an early inanimate stage in organic evolution. The various stages in inanimate matter, protocells, and evolved cells and the degree of order that they represent comport with the second law of thermodynamics on a cosmic scale. 相似文献
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Nicholas E. Curtis Sidney K. Pierce Steven E. Massey Julie A. Schwartz Timothy K. Maugel 《Marine Biology》2007,150(5):797-806
The adult, sacoglossan sea slug, Elysia clarki (Pierce et al. in Molluscan Res 26, 2006), sequesters functional chloroplasts in cells of the digestive diverticula from four species of macroalgae in the order Bryopsidales
(Penicillus capitatus, Penicillus lamourouxii, Halimeda incrassata, and Halimeda monile). Feeding experiments were conducted in December, 2003, using individuals raised in the laboratory from egg masses laid by
E. clarki adults which had been collected from Grassy Key, Florida, USA, and 29 species of macroalgae collected from the Florida Keys,
Tampa Bay, Tarpon Springs, Florida, or Woods Hole, Massachusetts or obtained from the Culture Collection of Algae at the University
of Texas at Austin, Texas. For the first 14-day post-metamorphosis, juveniles ate only the thin filamentous species, Bryopsis plumosa or Derbesia tenuissima. Transmission electron microscopy showed that the chloroplasts from both algae were sequestered intracellularly in juvenile
slugs. Individuals offered any other macroalga, including the four species fed on by adults, did not feed on or incorporate
any chloroplasts, and soon died. Juveniles switched from B. plumosa to P. capitatus at a length of ∼ 1.0 cm, and fixed for microscopy 14 days later had intact intracellular chloroplasts from both algae. Nucleotide
sequences of the chloroplast gene, rbcL, from DNA extracted from E. clarki, collected from Vaca Key, Florida, were aligned with 22 other available macroalgal rbcL sequences indicating that these E. clarki adults had fed on three species of algae in the Bryopsidales including Bryopsis pennata, and TEM results partially confirmed this conclusion. 相似文献