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Mala Mahalanabis 《Pure and Applied Geophysics》1971,92(1):52-61
Summary This paper deals with the study of the disturbances in an inhomogeneous semi-infinite viscoelastic bar of Reiss type acted upon by an impulsive force at its finite end, under the influence of a primary static magnetic field. 相似文献
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Influence of IHSS Standard and Reference Materials on Copper and Mercury Toxicity to Vibrio fischeri
The reduction in light emission of the marine bacterium Vibrio fischeri used in the standard Microtox® bioassay was measured for the metals copper and mercury. The concentration at which the light emission was reduced by 50% (EC50) was determined to be (3.43 ± 0.83) μmol/L for Cu2+ and (0.66 ± 0.01) μmol/L for Hg2+. The reduction of the toxicity of these metals by humic and fulvic acids were studied using IHSS Standard and Reference Materials. Copper toxicity was reduced 17...20% by the soil and peat fulvic acids and 9...20% by the aquatic fulvic acids. While there appeared to be little difference in the reduction of Cu toxicity by fulvic acids from soils, peats, or aquatic systems, Hg toxicity was reduced 3.6...7.3% by the soils and peats, while aquatic fulvic acids reduced Hg toxicity 14...16%. Soil fulvic acids appear to have significantly less capacity to reduce Hg toxicity than Cu toxicity. Humic acids had much higher reductions of Cu toxicity (44...124%) compared to the fulvic acids, with little difference between aquatic and soil or peat humic acids, 44...124% and 67...100%, respectively. However, humic and fulvic acids, regardless of origin, had approximately the same effect on Hg toxicity with 3.5...16% reduction by fulvic acids and 8...20% reduction by humic acids. Unlike the fulvic acids, no clear trend was observed relative to origin of the humic acids. There was no correlation between percent reduction of Cu or Hg toxicity by the organic compounds and copper binding capacity (CuBC), C/N ratio, or carboxyl content of the materials. Examination of natural organic matter (NOM) isolated by reverse osmosis techniques from three water sources had reductions of both Cu and Hg toxicity that were most similar to the Suwannee River and Nordic fulvic acids. 相似文献
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A case study was carried out in 2000 in the shallow coastal area of the Northern Adriatic Sea (Gulf of Trieste) where untreated domestic sewage and industrial wastes are discharged at rate of 5500 m3·day?1. The sewage plume above the outfall was followed using faecal coliforms (FC) and overturning length scale (lT). The latter was rejected as a marker as the discharge conditions prohibit following the turbulence of sewage water. Intermittent sewage discharge is reflected in the minimal effect of eutrophication. Increase of phytoplankton biomass is thus only minor compared with the unpolluted area regardless of elevated concentrations of sewage‐derived nutrients (confirmed by correlation coefficients between FC and NH4+, TP, PO43?: 0.78, 0.71 and 0.67, respectively). Deteriorated trophic status, determined by the TRIX index, was observed only in the surface layer (average TRIX: 5.67). High FC content well above the regulation limit (up to 2.6 × 105 FC·100 ml?1) represents, therefore, the major negative impact of the improperly treated waste for the risk to human health. 相似文献
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The neuroprotective role of P-glycoprotein, a multixenobiotic resistance transporter (ABCB1/MDR1), in the blood-brain barrier in fish was examined using behavioural toxicological assays. P-glycoprotein acts as cellular efflux pump to prevent substrates from accumulating in the brain, including environmental contaminants such as ivermectin, a common aquaculture pesticide and mammalian anti-parasitic drug. The behavioural toxicological assays were developed to determine the neuropathological effect of ivermectin in killifish (Fundulus heteroclitus). P-glycoprotein function and thus blood-brain barrier integrity can be compromised by chemosensitizers that inhibit transport activity. Fish treated with ivermectin and the P-glycoprotein inhibitor cyclosporin A were significantly more sensitive and succumbed more rapidly to tilting, lethargy, slowing of pectoral-fin movement and loss of haptic-reactivity compared to fish treated with ivermectin-only. P-glycoprotein inhibition is associated with significantly earlier onset and increased mortality in ivermectin-exposed fish. Our results suggest that P-glycoprotein confers resistance against ivermectin-induced behavioural neuropathology and mortality in fish. This assay provides us with a non-invasive tool to study P-glycoprotein function in the blood-brain barrier and evaluate the behavioural effects of potential environmental neurotoxins. 相似文献
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Abhijit Bhattacharyya Sukumar Biswas Barun K. Chatterjee Mala Das Pradipta K. Das Tapan K. Das Tarun K. De M.H. Engineer Rabi N. Mukherjee Sibaji Raha S.C. Roy Swapan K. Saha A.K. Sen Bikash Sinha Debapriyo Syam 《Astrophysics and Space Science》1997,250(2):313-326
A Total Solar Eclipse (TSE) was observed from Diamond Harbour (lat. 22.2°N, long 88.2°E) on 24 October 1995. The variation of -ray intensity was measured in the energy range of 0.3–3.0 MeV for different time spans throughout the period of the eclipse. A CR-39 detector was used to look at the change in the fluxes of neutral and charged particles. The maximum drop ( 25%) in the intensity of -ray was observed in the range 2.5–3 MeV during TSE. The CR-39 results showed the appearance of a good number of tracks and a small variation of proton and neutron flux of 10% which was not significant statistically. Low energy -ray fluxes at sea level originate from the secondary electron-photon components of cosmic rays in the atmosphere; its modulation by TSE is interpreted as follows. The cooling of the atmosphere in the path of the umbra induces a reduction of the height of the main production layer of the nuclear component, as a result of which, fewer µ± mesons (from the decay of the± mesons) decay to e±. This leads to a small reduction in the flux of electron-photon component at sea level which originates from this branch; the main branch of e - component from 0 decay remains nearly unaffected. As the total mass of air remains the same, little or no change in the slow proton or the neutron flux at sea level is expected. These are consistent with the present observations. For a better understanding, further studies of this new phenomenon during future TSE are suggested. 相似文献
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Boris Petelin Igor Kononenko Vlado Malačič Matjaž Kukar 《International journal of geographical information science》2019,33(10):1936-1959
We present an adaptation and application of frequent subgraph mining (FSM) in a time series of spatial multi-level directed graphs depicting probabilistic transitions of water masses between neighboring sea areas within a given time interval. The directed graphs are created from the results of the numerical model, the Mediterranean Ocean Forecasting System. We assign unique labels (geographical locations) to vertices of the multi-level directed graphs. Then, we add the edge labels as discretized values of the probabilities of transitions between vertices. This modification allows the use of the established algorithm gSpan to search for frequently directed subgraphs in the sequence of such directed graphs. Thus, we obtain both general and specific subgraphs, such as convergences, divergences, and paths of the ocean currents in the numerical model. The resulting substructures, revealed by directed subgraphs, match oceanographic structures (gyres, convergences/divergences, and paths) deduced from field observations, and can also serve as a tool for the validation of the numerical model of circulation in the sea. 相似文献
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