UV observations of the symbiotic star EG And

EG And is a S-type symbiotic star. Presented are UV observations made by IUE from 1978 to 1991. From these observations the electron density and the electron temperature were obtained. The size of the Heii emitting region was estimated as 7.3R. Line and continuum variations confirm the binary nature of EG And.     

Multi-trial biomarker approach in Meganyctiphanes norvegica: a potential early indicator of health status of the Mediterranean "whale sanctuary."

The aim of this study was to propose a suite of biomarkers (BPMO activity, NADPH-cytocrome c reductase, NADH-ferricyanide reductase. esterases, porphyrins, vitellogenin and zona radiata proteins) and residue levels (organochlorines, PAHs and heavy metals) in the zooplanktonic euphausiid Meganyctiphanes norvegica as a potential multi-disciplinary diagnostic tool for assessment of the health status of the Mediterranean "whale sanctuary". Very little difference in BPMO was detected between sites, with values ranging from 0.75 to 2.68 U.A.F./mg prot/h. On the other hand larger differences between sites were found for reductase activities. Esterases (AChE), porphyrins (Copro-, Uro-, Proto-porphyrins) vitellogenin and zona radiata proteins were also detectable in this zooplanctonic species. Hg showed mean levels of 0.141 ppm d.w., Cd 0.119 ppm d.w. and Pb 0.496 ppm d.w. Total PAHs ranged from 860.7 to 5,037.9 ng/g d.w., carcinogenic PAHs from 40.3 to 141.7 ng/g d.w., HCB from 3.5 to 11.6 ng/g d.w., DDTs from 45.3 to 163.2 ng/g d.w. and the PCBs from 84.6 to 210.2 ng/g d.w.     

Grain size characteristics of superficial sediments of the Gulf of Tunis (NE Tunisia)

This work presents a recent grain size study characterizing superficial sediments of the whole sectors of the Gulf of Tunis which extends from Sidi Ali El Mekki to Sidi Daoued. In this study, a total of 112 samples were collected from different depths following 26 profiles perpendicular to the shore and from rivers. The determination of the proportions of coarse and fine fractions and the interpretation of the grain size results lead to dividing the Gulf of Tunis into two principal coasts: (1) the western coast situated between Sidi Ali El Mekki and Borj Cédria, which is characterized by three sedimentary facies: (a) a sandy facies along the coastline, (b) a mixed facies between Ghar El Melh and Raoued, near the Medjerda River, and between La Goulette and Ezzahra, near the Miliane River, and (c) a muddy facies between Ghar El Melh and Kalâat El Andalous and covered by fine to very fine sands, and (2) the eastern coast, which is characterized by a sandy facies and covered by medium to coarse sands. The dominant N–E and N–W waves generate longshore currents that provide sediment transport following the directions N–S, from Sidi Ali El Mekki to Kalâat El Andalous; SE–NW, from Gammarth to Raoued; NE–SW, from Sidi Bou Saïd to La Goulette and from Sidi Daoued to Bir El Jadi; SE–NW, from Hammam-Plage to Ezzahra; and SW–NE, from Port aux Princes to Rtiba.     

辽宁五龙金矿黄铁矿的热电性标型特征

黄铁矿是五龙金矿的主要载金矿物之一，热电性以P型为主，占总数的90.8%，变化范围为4.3-392.0uV/℃，N型占9.2%，变化范围为-28.6--177.1uV/℃；不同世代黄铁矿热电性不同，第一世代为P型，第二、三世代为P、N混合型；横向上从矿体到围岩；热电系数由小变大，As使其呈P型，而C0、Ni使其呈N型。     

Gravity analysis of salt structures. An example from the El Kef‐Ouargha region (northern Tunisia)

Triassic outcrops in the Atlassic zone of northern Tunisia may be modelled in two ways: salt bodies piercing through Cretaceous terrains or Triassic salt flows stratified within an Albian series. Both models find support from gravity data and are debatable. To evaluate the mass distribution changes with depth, the Bouguer anomaly of the El Kef‐Ouargha region was successively decomposed into regional and residual components to construct multiple pseudo‐depth slices and apparent density maps. Analyses of gravity lows clearly show a vertical continuity of less dense materials below the Triassic salt outcrops. These features can be explained by salt diapirism during Mesozoic and Cenozoic. Further, gravity data tend to indicate less dense materials below Aptian outcropping in Jebel Aite (Oued Bou Adila); thus suggesting Triassic materials occurring at depth. In addition, dense entities were recognized under Mio‐Pliocene and Quaternary deposits, which are thought to correspond to Cretaceous paleoshoals currently collapsed by non‐outcropping faults. Our findings lend support to a diapir model intruding overburden rather than the salt glacier model stratified in the Albian series proposed by some authors as the genetic structural model for Triassic material‐bearing series in the north of Tunisia.     

Experimental investigation of the time-dependent response of unreinforced and reinforced tunnel faces in cohesive soils

In spite of the increasing diffusion of tunnel boring machines, conventional tunnelling is still preferred for economic reasons in case of short tunnels, unconventional cross sections or irregular tunnel trajectories. In conventional tunnelling, the mechanical response of the tunnel front is a main concern and, when tunnels are excavated in cohesive soils, this is dominated by the time factor, related to geometry, to the mean excavation rate and to the hydro-mechanical properties of the materials involved. This is particularly evident during excavation standstill: front displacements progressively increase with time and, in many cases, the system response under long-term conditions becomes unstable. In conventional tunnelling, a common technique employed to improve the system response (under both short- and long-term conditions) is the installation of fibreglass tubes within the advance core. In this paper, the mechanical response of both unreinforced and reinforced deep tunnel fronts in cohesive soils is experimentally analysed. In particular, the results of a series of 1 g small-scale tests, taking into account both the influence of the excavation rate (the unloading time) on the system response and the evolution with time of the tunnel face displacements, induced by a rapid reduction in the horizontal stress applied on the tunnel face, are reported.     

Soil-precipitation feedbacks during the South American Monsoon as simulated by a regional climate model

We summarize the recent progress in regional climate modeling in South America with the Rossby Centre regional atmospheric climate model (RCA3-E), with emphasis on soil moisture processes. A series of climatological integrations using a continental scale domain nested in reanalysis data were carried out for the initial and mature stages of the South American Monsoon System (SAMS) of 1993–92 and were analyzed on seasonal and monthly timescales. The role of including a spatially varying soil depth, which extends to 8 m in tropical forest, was evaluated against the standard constant soil depth of the model of about 2 m, through two five member ensemble simulations. The influence of the soil depth was relatively weak, with both beneficial and detrimental effects on the simulation of the seasonal mean rainfall. Secondly, two ensembles that differ in their initial state of soil moisture were prepared to study the influence of anomalously dry and wet soil moisture initial conditions on the intraseasonal development of the SAMS. In these simulations the austral winter soil moisture initial condition has a strong influence on wet season rainfall over feed back upon the monsoon, not only over the Amazon region but in subtropical South America as well. Finally, we calculated the soil moisture–precipitation coupling strength through comparing a ten member ensemble forced by the same space–time series of soil moisture fields with an ensemble with interactive soil moisture. Coupling strength is defined as the degree to which the prescribed boundary conditions affect some atmospheric quantity in a climate model, in this context a quantification of the fraction of atmospheric variability that can be ascribed to soil moisture anomalies. La Plata Basin appears as a region where the precipitation is partly controlled by soil moisture, especially in November and January. The continental convective monsoon regions and subtropical South America appears as a region with relatively high coupling strength during the mature phase of monsoon development.     

黑龙江省老柞山金矿床毒砂热电性研究

毒砂是老柞山金矿主要载金矿物。早期与晚期成矿作用形成的毒砂 ,其热电性具明显差异 :早期毒砂热电系数为正值 ,平均 2 5 0 .3μV /℃ ,P型导电 ;晚期毒砂热电系数为负值 ,平均- 2 16 .9μV /℃ ,为N型导电。通过对不同成矿期以及同一样品中不同导型毒砂的热电性特征与成分关系的研究得出 :毒砂的热电性特征由As、S相对含量决定 ,若为富As型毒砂 ,则为P型导电 ,若为富S型毒砂 ,则为N型导电。     

A full-scale study of Darcy-Weisbach friction factor for channels vegetated by riparian species

In this article, an open channel flow resistance equation, deduced applying dimensional analysis and incomplete self-similarity condition for the flow velocity distribution, was tested using measurements carried out in a full-scale channel equipped with three types of riparian plants (Salix alba L., Salix caprea L. and Alnus glutinosa L.). In the experimental channel, having banks lined with boulders, the vegetation branches were anchored in a concrete bottom. For each species, the measurements were carried out with plants having different amounts of leaves, different plant density and plant area index. The relationship between the scale factor Γ of the velocity profile and the Froude number was separately calibrated by measurements carried out without and with vegetation. The component of Darcy-Weisbach friction factor corresponding to the riparian vegetation f_v was calculated as the difference between the measured friction factor value (channel grain roughness + vegetation) and that calculated for the channel without vegetation in the same hydraulic conditions. Using these f_v values, the relationship between the scale factor Γ and the Froude number was calibrated. In this last relationship, a scaling coefficient a varying with the investigated vegetation type was introduced. This coefficient, as expected, gives the highest friction factor values for vegetation having branches with leaves. The theoretical flow resistance law, coupled with the relationship for estimating the Γ function having a scaling coefficient different for each investigated vegetation type, allowed an accurate estimate of the Darcy-Weisbach friction factor (errors less than or equal to 20% for 82.6% of the investigated cases). Finally, for the investigated vegetation species that are characterized by a condition with few leaves or leafless, the scaling coefficient a resulted strongly related to the bending stiffness. This analysis demonstrated that the highest Darcy-Weisbach friction factors correspond to vegetation species characterized by the highest values of bending stiffness. The friction factor values calculated for this last condition are characterized by errors that were less than or equal to ±20% for 90.6% of cases.