Distribución espacial de copépodos Antárticos en Bahía Fíldes durante el verano de 2012

Indexación: Web of Science; Scielo.The Antarctic Chilean peninsula, is characterized for being stable in its oceanographic conditions. Nevertheless, its coastal zones, such as bays, may have more variable physical conditions, both spatially and temporally. It has been observed that a remarkable interaction between the oceanographic conditions and spatial distribution patterns of zooplankton occurs. However, there is no good understanding of how these interactions affect the horizontal and vertical distribution of zooplankton living in these areas. The present study shows the changes that occur at the level of the zooplankton community structure, specifically in the copepods assembly of Fíldes Bay. The results show that copepods of the Oithonidae family are abundant in coastal areas of the bay meanwhile Calanidae copepods are abundant in zones adjacent to Bransfield Strait and found only in low abundance at the interior of the bay. These findings indicate differences in the ensemble of copepods along the bay with changes in the abundance and distribution of dominant groups of copepods commonly found in the Antarctic Peninsula and Drake Passage waters.La Península Antártica Chilena, se caracteriza por ser estable en su condición oceanográfica, sin embargo sus zonas costeras como bahías pueden presentar condiciones físicas variables tanto espacial como temporalmente. Se ha señalado que existe una importante interacción entre las condiciones oceanográficas y patrones de distribución espacial del zooplancton, sin embargo, no existe mayor evidencia acerca de cómo esta interacción afecta la distribución horizontal y vertical del zooplancton que habita estas zonas. El presente estudio muestra evidencias de los cambios que ocurren a nivel de estructura comunitaria del zooplancton, específicamente en el ensamble de copépodos al interior de Bahía Fíldes. Los resultados muestran que copépodos de la familia Oithonidae son abundantes en zonas costeras de la bahía mientras que copépodos de la familia Calanidae son abundantes en zonas contiguas al Estrecho Bransfield encontrándose en escasa abundancia al interior de la bahía. Estos hallazgos indican que existen diferencias en el ensamble de copépodos a lo largo de la bahía con cambios en términos de abundancia y distribución de grupos dominantes encontrados comúnmente en la Península Antártica y aguas cercanas al paso Drake.http://ref.scielo.org/f3m7x

Present and potential land use mapping in Mexico

The Mexican Water Plan (MWP) conducted studies of present and potential land use in Mexico using LANDSAT-1 satellite imagery. Present land use studies were carried out all over the country (197 million hectares); nine soil uses were mapped according to the first classification level recommended by the U.S. Geological Survey. Also 6.3 million hectares of land with advanced erosion were detected. Work was executed at a rate of 8 million hectares per month; reliability was 90% and the cost of only 0.1 cents/hectare. The potential land use study was performed in 45 million hectares at a rate of 4 million hectares per month and at a cost of 0.33 cents/hectare. Soil units according to FAO classification were delineated scale 1:1 million; interpretative maps were also prepared dealing with potential agricultural productivity carrying capacity for cattle, water, erosion risk, and slope ranges

Cooperative Analysis of Determination of Parts of Speech by Structure in American-English and in Spanish

A monograph presented to the faculty of the Department of English at Morehead State University in partial fulfillment of the requirements for the Degree of Master of Arts by Raul F. Lagos in July of 1971

Surface Effects on the Mechanical Elongation of AuCu Nanowires: De-alloying and the Formation of Mixed Suspended Atomic Chains

We report here an atomistic study of the mechanical deformation of AuxCu(1-x) atomic-size wires (NWs) by means of high resolution transmission electron microscopy (HRTEM) experiments. Molecular dynamics simulations were also carried out in order to obtain deeper insights on the dynamical properties of stretched NWs. The mechanical properties are significantly dependent on the chemical composition that evolves in time at the junction; some structures exhibit a remarkable de-alloying behavior. Also, our results represent the first experimental realization of mixed linear atomic chains (LACs) among transition and noble metals; in particular, surface energies induce chemical gradients on NW surfaces that can be exploited to control the relative LAC compositions (different number of gold and copper atoms). The implications of these results for nanocatalysis and spin transport of one-atom-thick metal wires are addressed.Comment: Accepted to Journal of Applied Physics (JAP

Cooking pasta with Lie groups

We extend the (gauged) Skyrme model to the case in which the global isospin group (which usually is taken to be SU(N)) is a generic compact connected Lie group G. We analyze the corresponding field equations in (3+1) dimensions from a group theory point of view. Several solutions can be constructed analytically and are determined by the embeddings of three dimensional simple Lie groups into G, in a generic irreducible representation. These solutions represent the so-called nuclear pasta state configurations of nuclear matter at low energy. We employ the Dynkin explicit classification of all three dimensional Lie subgroups of exceptional Lie group to classify all such solutions in the case G is an exceptional simple Lie group, and give all ingredients to construct them explicitly. As an example, we construct the explicit solutions for G=G2. We then extend our ansatz to include the minimal coupling of the Skyrme field to a U(1) gauge field. We extend the definition of the topological charge to this case and then concentrate our attention to the electromagnetic case. After imposing a \u201cfree force condition\u201d on the gauge field, the complete set of coupled field equations corresponding to the gauged Skyrme model minimally coupled to an Abelian gauge field is reduced to just one linear ODE keeping alive the topological charge. We discuss the cases in which such ODE belongs to the (Whittaker-)Hill and Mathieu types

Job security and long-term investment: an experimental analysis

We investigate an experimental labor market setting in which we introduce the novel aspect that workers have the chance of investing money in a long-term project in order to increase their income. We find a strong relationship between what happens inside the labor market (worker's performance) and what happens outside the labor market (long-term investment). Contrary to the theoretical predictions with selfish preferences, we find that the mere presence of long-term projects acts as an effort-enforcement device; this effect seems to be driven by an increase in long-term employment relationships. In the other direction, long-term labor relationships seem to provide a safer environment for undertaking successful long-term projects. This article also considers three different types of experimental labor contracts. We find that performance-based dismissal barriers, whereby firms are required to retain workers if they have satisfied the effort level required by firms, lead to more long-term employment relationships and higher overall productivity. As theory predicts, the presence of renewable dismissal barriers makes it likely that workers will provide the desired effort level. Firms appear to correctly anticipate this, leading to greater social efficiency

Most EL CVn systems are inner binaries of hierarchical triples

In spite of their importance for modern astronomy, we do not fully understand how close binary stars containing at least one white dwarf form from main sequence binary stars. The discovery of EL CVn binaries, close pre-white dwarfs with A/F main sequence star companions, offers now the unique possibility to test models of close compact binary star formation. Binary evolution theories predict that these EL CVn stars descend from very close main sequence binaries with orbital periods shorter than 3 days. If this is correct, nearly all EL CVn stars should be inner binaries of hierarchical triples because more than 95 per cent of very close main sequence binaries (the alleged progenitor systems) are found to be hierarchical triples. We here present SPHERE/IRDIS observations of five EL CVn binaries, finding in all of them tertiary objects, as predicted. We conclude that EL CVn systems are inner binaries of hierarchical triples and indeed descend from very close main sequence binaries that experience stable mass transfer

Mechanical Deformation Of Nanoscale Metal Rods: When Size And Shape Matter.

Face centered cubic metals deform mainly by propagating partial dislocations generating planar fault ribbons. How do metals deform if the size is smaller than the fault ribbons? We studied the elongation of Au and Pt nanorods by in situ electron microscopy and ab initio calculations. Planar fault activation barriers are so low that, for each temperature, a minimal rod size is required to become active for releasing elastic energy. Surface effects dominate deformation energetics; system size and shape determine the preferred fault gliding directions which induce different tensile and compressive behavior.10605550

The hidden advantage of delegation: pareto-improvements in a gift-exchange game

This paper analyzes the effect on performance and earnings of delegating the wage choice to employees. Our results how that such delegation significantly increases effort levels. Moreover, we observe a Pareto-improvement, as the earnings of both employers and employees increase when employers delegate than when they do not. Interestingly, we also find that the employees’ performance under delegation is higher than under non-delegation, even for similar wages. While there is strong evidence that behavior reflects strategic considerations, this result also holds for one-shot interactions. A possible non-strategic motivation explaining the positive reaction to delegation is a sense of enhanced responsibility