Seismic site effects in a deep alluvial basin: numerical analysis by the boundary element method

The main purpose of the paper is the numerical analysis of seismic site effects in Caracas (Venezuela). The analysis is performed considering the boundary element method in the frequency domain. A numerical model including a part of the local topography is considered, it involves a deep alluvial deposit on an elastic bedrock. The amplification of seismic motion (SH-waves, weak motion) is analyzed in terms of level, occurring frequency and location. In this specific site of Caracas, the amplification factor is found to reach a maximum value of 25. Site effects occur in the thickest part of the basin for low frequencies (below 1.0 Hz) and in two intermediate thinner areas for frequencies above 1.0 Hz. The influence of both incidence and shear wave velocities is also investigated. A comparison with microtremor recordings is presented afterwards. The results of both numerical and experimental approaches are in good agreement in terms of fundamental frequencies in the deepest part of the basin. The boundary element method appears to be a reliable and efficient approach for the analysis of seismic site effects

The K-theoretic Farrell-Jones Conjecture for hyperbolic groups

We prove the K-theoretic Farrell-Jones Conjecture for hyperbolic groups with (twisted) coefficients in any associative ring with unit.Comment: 33 pages; final version; to appear in Invent. Mat

Anthropogenic Space Weather

Anthropogenic effects on the space environment started in the late 19th century and reached their peak in the 1960s when high-altitude nuclear explosions were carried out by the USA and the Soviet Union. These explosions created artificial radiation belts near Earth that resulted in major damages to several satellites. Another, unexpected impact of the high-altitude nuclear tests was the electromagnetic pulse (EMP) that can have devastating effects over a large geographic area (as large as the continental United States). Other anthropogenic impacts on the space environment include chemical release ex- periments, high-frequency wave heating of the ionosphere and the interaction of VLF waves with the radiation belts. This paper reviews the fundamental physical process behind these phenomena and discusses the observations of their impacts.Comment: 71 pages, 35 figure

Local amplification of deep mining induced vibrations - Part.2: Simulation of the ground motion in a coal basin

This work investigates the impact of deep coal mining induced vibrations on surface constructions using numerical tools. An experimental study of the geological site amplification and of its influence on mining induced vibrations has already been published in a previous paper (Part 1: Experimental evidence for site effects in a coal basin). Measurements have shown the existence of an amplification area in the southern part of the basin where drilling data have shown the presence of particularly fractured and soft stratigraphic units. The present study, using the Boundary Element Method (BEM) in the frequency domain, first investigates canonical geological structures in order to get general results for various sites. The amplification level at the surface is given as a function of the shape of the basin and of the velocity contrast with the bedrock. Next, the particular coal basin previously studied experimentally (Driad-Lebeau et al., 2009) is modeled numerically by BEM. The amplification phenomena characterized numerically for the induced vibrations are found to be compatible with the experimental findings: amplification level, frequency range, location. Finally, the whole work was necessary to fully assess the propagation and amplification of mine induced vibrations. The numerical results quantifying amplification can also be used to study other coal basins or various types of alluvial sites

Sapling size influences shade tolerance ranking among southern boreal tree species

1 Traditional rankings of shade tolerance of trees make little reference to individual size. However, greater respiratory loads with increasing sapling size imply that larger individuals will be less able to tolerate shade than smaller individuals of the same species and that there may be shifts among species in shade tolerance with size. 2 We tested this hypothesis using maximum likelihood estimation to develop individual-tree-based models of the probability of mortality as a function of recent growth rate for seven species: trembling aspen, paper birch, yellow birch, mountain maple, white spruce, balsam fir and eastern white cedar. 3 Shade tolerance of small individuals, as quantified by risk of mortality at low growth, was mostly consistent with traditional shade tolerance rankings such that cedar > balsam fir > white spruce > yellow birch > mountain maple = paper birch > aspen. 4 Differences in growth-dependent mortality were greatest between species in the smallest size classes. With increasing size, a reduced tolerance to shade was observed for all species except trembling aspen and thus species tended to converge in shade tolerance with size. At a given level of radial growth larger trees, apart from aspen, had a higher probability of mortality than smaller trees. 5 Successional processes associated with shade tolerance may thus be most important in the seedling stage and decrease with ontogeny

Evaluating synergy between marbofloxacin and gentamicin in Pseudomonas aeruginosa strains isolated from dogs with otitis externa

The aim of this study was to determine antimicrobial susceptibility of Pseudomonas aeruginosa strains to marbofloxacin and gentamicin, and investigate the possible synergistic, additive, indifferent or antagonistic effects between the two agents. P. aeruginosa strains can develop resistance quickly against certain antibiotics if used alone, thus the need emerges to find synergistic combinations. A total of 68 P. aeruginosa strains isolated from dogs were examined. In order to describe interactions between marbofloxacin and gentamicin the checkerboard microdilution method was utilized. The MICs (minimum inhibitory concentrations) for marbofloxacin and gentamicin were in the range 0.25–64 mg/L and 0.25–32 mg/L, respectively. The combination of marbofloxacin and gentamicin was more effective with a MIC range of 0.031–8 mg/L and a MIC90 of 1 mg/L, compared to 16 mg/L for marbofloxacin alone and 8 mg/L for gentamicin alone. The FIC (fractional inhibitory concentration) indices ranged from 0.0945 (pronounced synergy) to 1.0625 (indifference). Synergy between marbofloxacin and gentamicin was found in 33 isolates. The mean FIC index is 0.546, which represents a partial synergistic/additive effect close to the full synergy threshold. In vitro results indicate that marbofloxacin and gentamicin as partially synergistic agents may prove clinically useful in combination therapy against P. aeruginosa infections. Although marbofloxacin is not used in the human practice, the interactions between fluoroquinolones and aminoglycosides may have importance outside the veterinary field

Study of the effects of thermal regime and alternative hormonal treatments on the reproductive performance of European eel males (Anguilla anguilla) during induced sexual maturation

[EN] Since 1960, the European eel (Anguilla anguilla) has suffered a dramatic reduction in natural stocks. Breeding in captivity is considered an alternative, but obtaining high quality sperm seems basic on this regard. The main objective of this study was to assess the effects of three thermal regimes (two of them variable: T10 and T15; and one of them constant: T20) and three hormonal treatments with different hormones (hCG, hCGrec and PSMG) on the induction of maturation in European eel males. In the case of the thermal regimes, our results demonstrated that the onset and progression of spermiation are strongly influenced, and perhaps closely regulated, by water temperature. T20 demonstrated the best results in all the sperm parameters (volume, density, motility, kinetic features, etc.) throughout most weeks of treatment, becoming a reliable and productive method for inducing spermiation in this species. In the case of hormonal treatments, the onset and progression of spermiation in European eel males were influenced by the hormone used. In this respect, hCGrec produced the best results in all the sperm parameters including volume, density, motility, kinetic features, etc., throughout most weeks of treatment, thus becoming an effective alternative treatment to the standard hCG treatment used to induce spermiation in eel species. Moreover, hCGrec gave rise to the best economical profitability, making it possible to obtain good quality sperm samples at a lower price than by using the other two hormonal treatments. © 2012 Elsevier B.V. All rights reserved Guardar / Salir Siguiente >Funded by the European Community's 7th Framework Programme under the Theme 2 "Food, Agriculture and Fisheries, and Biotechnology", grant agreement no. 245257 (PRO-EEL) and Generalitat Valenciana (ACOMP/2012/086). Victor Gallego, Ilaria Mazzeo and M. Carmen Vilchez have predoctoral grants from the Spanish Ministry of Science and Innovation (MICINN), Generalitat Valenciana, and UPV PAID Programme (2011-S2-02-6521), respectively. Paulo C.F. Carneiro had post-doc grants from PAC-EMBRAPA and UPV PAID Programme (PAID-02-11). David S. Penaranda was supported by a contract co-financed by MICINN and UPV (PTA2011-4948-I).Gallego Albiach, V.; Mazzeo, I.; Vilchez Olivencia, MC.; Peñaranda, D.; Carneiro, PCF.; Pérez Igualada, LM.; Asturiano Nemesio, JF. (2012). Study of the effects of thermal regime and alternative hormonal treatments on the reproductive performance of European eel males (Anguilla anguilla) during induced sexual maturation. Aquaculture. 354:7-16. https://doi.org/10.1016/j.aquaculture.2012.04.041S71635