Evaporation of the Nerve Agent GB From Common Matrices: A Model‐System Study          下载免费PDF全文

Ishay Columbus  Itzhak Marcovitch  Shlomi Elias  Lea Yehezkel  Dana Marder  Victoria Nahum 《洁净——土壤、空气、水》2018,46(4)

  相似文献   

Mid-Wisconsin seasonal temperatures reconstructed from fossil beetle assemblages in eastern North America: comparisons with other proxy records from the Northern Hemisphere     

Scott A. Elias 《第四纪科学杂志》1999,14(3):255-262

Mutual climatic range (MCR) analysis was applied to 15 North American beetle assemblages spanning the interval from > 52 000 to 17 200 yr BP, bracketing a Mid-Wisconsin interstadial interval. The analyses yielded estimates of mean July (TMAX) and mean January (TMIN) temperatures. The oldest assemblage (> 52 ka) yielded TMAX values 7.5–8°C lower than present and TMIN values 15–18°C lower than present. A Mid-Wisconsin interstadial warming dating from 43.5–39 ka was rapid and intense. At the peak of the warming event, about 42 ka, TMAX values were only 1–2°C lower than modern. This level of amelioration apparently lasted only about 2000–3000 yr. By 23.7 ka, TMAX values declined to 11.5–10°C lower than modern, but another, small-scale amelioration is indicated by assemblages dating from 20.5 to 19.7 ka. The interstadial event recorded from the site at Titusville, Pennsylvania closely matches the timing and intensity of the climate change estimated from British beetle faunas in the Upton Warren interstadial. Another warm interval (ca. 31–32.5 ka) has been documented from fossil beetle assemblages in Europe and North America. Copyright © 1999 John Wiley & Sons, Ltd.  相似文献   

Mars: The spectral albedo (0.3–2.5μ) of small bright and dark regions     

Thomas B. McCordJonathan H. Elias 《Icarus》1971

A review of the available spectral geometric albedo measurements for Mars was presented earlier for the spectral region 0.3 to 1.1μ. A new observational study has greatly increased the store of data, especially for small Martian regions and for the infrared spectral region 1.0 to 2.5μ. Here we combine the new data with data both from the earlier review and, for the infrared spectral region, from the literature. We present a more complete picture of Martian spectral reflectivity properties than was available. This study should provide a more firm basis upon which models of Martian surface composition can be built. At visible wavelengths the Mars dark area Syrtis Major is red rather than green or grey in color; the bright area Arabia is even redder than Syrtis Major. Absorption bands, which differ between bright and dark areas, appear in the reflection curves. The 1μ absorption feature for dark areas is confirmed and more completely described. A previously unreported absorption band near 0.95μ for bright areas appears along with several absorption features in the infrared. The geometric albedo for Arabia reaches a maximum of about 0.43 at 1μ. The Bond albedo for this same area reaches a maximum of 60%. The bright area Arabia is occasionally three times brighter than the dark area Syrtis Major at red wavelengths. Published infrared reflection data available for Mars are not in complete agreement. Changes in brightness and color of Arabia are discussed which are not in agreement with traditional darkening wave theory.  相似文献   

Predatory pelagic fishes of the Bijagós Archipelago (Guinea-Bissau) show high overlap in diets dominated by sardinella     

E Correia  JP Granadeiro  A Regalla  E Dias  A Almeida  P Catry 《African Journal of Marine Science》2017,39(4):389-396

Knowledge of trophic interactions between the key components of marine communities is required to understand food-web dynamics and develop ecosystem-based management approaches. In West Africa, where fisheries sustain the livelihoods of a significant part of the human population, this understanding is even more urgent, especially in the face of rapidly expanding fisheries and some stock collapses in the region. We studied the feeding ecology of the Crevalle jack Caranx hippos, West African Spanish mackerel Scomberomorus tritor and Guinean barracuda Sphyraena afra in the Bijagós Archipelago, Guinea-Bissau. These are the most abundant pelagic predatory teleost fishes in the area, but little is known about their ecology despite being species with commercial and recreational value, and they likely also play an important role in various African coastal ecosystems. Our findings show a high degree of dietary overlap among these three predator species, despite some degree of segregation by prey size and type. All three predators depend on Sardinella maderensis as the most important prey, which together with other members of the Clupeidae represented 47–96% of the ingested prey items. There was little difference in the diets of the predators between the dry and rainy seasons. These novel findings suggest a ‘wasp-waist’-structured ecosystem in the Bijagós Archipelago in which S. maderensis is the central small-sized pelagic fish species, and stress the need for an ecosystem-based approach to fisheries management in the region, with precautionary measures taken to avoid the overexploitation of clupeids.  相似文献   

Probabilistic evaluation of tunnel face stability in spatially random soils using sparse polynomial chaos expansion with global sensitivity analysis     

Qiujing Pan  Daniel Dias 《Acta Geotechnica》2017,12(6):1415-1429

The sparse polynomial chaos expansion is employed to perform a probabilistic analysis of the tunnel face stability in the spatially random soils. A shield tunnel under compressed air is considered which implies that the applied pressure is uniformly distributed on the tunnel face. Two sets of failure mechanisms in the context of the limit analysis theory with respect to the frictional and the purely cohesive soils are used to calculate the required face pressure. In the case of the frictional soils, the cohesion and the friction angle are modeled as two anisotropic cross-correlated lognormal random fields; for the purely cohesive soils, the cohesion and the unit weight are modeled as two anisotropic independent lognormal random fields. The influences of the spatial variability and of the cross-correlation between the cohesion and the friction angle on the probability density function of the required face pressure, on the sensitivity index and on the failure probability are discussed. The obtained results show that the spatial variability has an important influence on the probability density function as well as the failure probability, but it has a negligible impact on the Sobol’s index.  相似文献   

Estimation of the Crustal Bulk Properties Beneath Mainland Portugal from P-Wave Teleseismic Receiver Functions     

Süleyman Dündar  Nuno A. Dias  Graça Silveira  Rainer Kind  Lev Vinnik  Luís Matias  Marcelo Bianchi 《Pure and Applied Geophysics》2016,173(6):1949-1970

  相似文献   

Geospatial Investigation into Groundwater Pollution and Water Quality Supported by Satellite Data: A Case Study from the Evros River (Eastern Mediterranean)     

Dimitriou Elias  Mentzafou Angeliki  Markogianni Vasiliki  Tzortziou Maria  Zeri Christina 《Pure and Applied Geophysics》2014,171(6):977-995

Managing water resources, in terms of both quality and quantity, in transboundary rivers is a difficult and challenging task that requires efficient cross-border cooperation and transparency. Groundwater pollution risk assessment and mapping techniques over the full catchment area are important tools that could be used as part of these water resource management efforts, to estimate pollution pressures and optimize land planning processes. The Evros river catchment is the second largest river in Eastern Europe and sustains a population of 3.6 million people in three different countries (Bulgaria, Turkey and Greece). This study provides detailed information on the main pollution sources and pressures in the Evros catchment and, for the first time, applies, assesses and evaluates a groundwater pollution risk mapping technique using satellite observations (Landsat NDVI) and an extensive dataset of field measurements covering different seasons and multiple years. We found that approximately 40 % of the Greek part of the Evros catchment is characterized as of high and very high pollution risk, while 14 % of the study area is classified as of moderate risk. Both the modeled and measured water quality status of the river showed large spatiotemporal variations consistent with the strong anthropogenic pressures in this system, especially on the northern and central segments of the catchment. The pollutants identified illustrate inputs of agrochemicals and urban wastes in the river. High correlation coefficients (R between 0.79 and 0.85) were found between estimated pollution risks and measured concentrations of those chemical parameters that are mainly attributed to anthropogenic activities rather than in situ biogeochemical processes. The pollution risk method described here could be used elsewhere as a decision support tool for mitigating the impact of hazardous human activities and improving management of groundwater resources.  相似文献   

Dynamically equivalent rocking structures          下载免费PDF全文

Matthew J. DeJong  Elias G. Dimitrakopoulos 《地震工程与结构动力学》2014,43(10):1543-1563

Predicting the rocking response of structures to ground motion is important for assessment of existing structures, which may be vulnerable to uplift and overturning, as well as for designs which employ rocking as a means of seismic isolation. However, the majority of studies utilize a single rocking block to characterize rocking motion. In this paper, a methodology is proposed to derive equivalence between the single rocking block and various rocking mechanisms, yielding a set of fundamental rocking parameters. Specific structures that have exact dynamic equivalence with a single rocking block, are first reviewed. Subsequently, approximate equivalence between single and multiple block mechanisms is achieved through local linearization of the relevant equations of motion. The approximation error associated with linearization is quantified for three essential mechanisms, providing a measure of the confidence with which the proposed methodology can be applied. Copyright © 2014 John Wiley & Sons, Ltd.  相似文献   

Structural control of groundwater flow regimes and groundwater chemistry along the lower reaches of the Zerka River,West Jordan,using remote sensing,GIS, and field methods     

Taleb Odeh  Elias Salameh  Mario Schirmer  Gerhard Strauch 《Environmental Geology》2009,58(8):1797-1810

A hydrogeological study was completed within a sub-catchment of the Zerka River drainage basin, in western Jordan. The system is characterized by anticlinal bending with an axis trending SSW–NNE and plunging a few degrees in the SSW direction. The anticlinal structure diverts groundwater flow towards the SSW while the strike-slipe faults cause the groundwater to diverge where the fault is perpendicular to the groundwater flow lines, and to converge where the fault is parallel to the groundwater flow lines. A direct relationship was found between the location of springs and the type of groundwater flow with regard to the amount of discharge wherein large spring discharges are located in zones of converging groundwater flow lines. In areas where faults are not abundant, the groundwater retention time in the aquifers is long and a zonation of the electrical conductivity was detected due to mineral dissolution. By controlling groundwater flow, the anticlinal setting produces three genetic groups of groundwater flow systems: (1) alkaline–earth alkaline water which is predominately a bicarbonate-type composition, (2) alkaline–earth alkaline water which is predominately bicarbonate–sulfate, and (3) alkaline–earth alkaline water with a high alkaline component.  相似文献   

Sediments Quality Assessment of Jacarepaguá Lagoon: The Venue of the 2011 Rock in Rio     

José Tavares Araruna Júnior  Paula Elias Benedetti  Patrício José Moreira Pires  Ricardo Froitzheim Rinelli de Almeida 《洁净——土壤、空气、水》2012,40(9):906-910

In order to aid in the efforts of the 2016 Olympic Games, the organizers of 2011 Rock in Rio decided to build a permanent venue next to the Olympic Park. The area is problematic from the geotechnical point of view since it presents soils with low shear strength, low permeability, and high plasticity, so major soil improvement works were carried out. Bored soil–cement columns were placed to increase soil shear strength and reduce compressibility. A meter thick fill composed of gneiss residual soil was placed and trenches were digged to drain rainwater. However, earlier studies conducted on Jacarepaguá Lagoon have detected the presence of heavy metals in these sediments. In this study, an environmental survey on the Jacarepaguá Lagoon sediments took place in order to choose a place where its sediments could be dredged to be later used in the drainage facilities. The results indicated areas where the threshold level 1 (low probability of adverse effects) issued by the general procedures for sediments quality assessments for dredging purposes, Resolution no 344 of the Brazilian Federal Government, was surpassed. Levels above the limits established for cadmium (Cd), lead (Pb), copper (Cu), nickel (Ni), and zinc (Zn) were detected. Based on this consideration the State Environmental Agency issued a permit allowing the organizers of 2011 Rock in Rio to dredge an area close to City of Rock in order to obtain coarse sediments for the drainage facilities. In addition, it was found that those sediments were ideal for this application since their hydraulic conductivity is on the order of 10^?2 cm/s.  相似文献