Testicular histology of Mustelus schmitti springer, 1939 (Elasmobranchii, triakidae)

Mustelus schmitti presenta unos testiculos de desarrollo diametrico en la que espermatocistos forma redonda muestran una disposición zonal. Cada zona tiene espermatocistos que contienen células germinales en una sola fase de desarrollo. Los especímenes adultos mostraron seis etapas diferentes que van desde espermatogonias a espermatozoides maduros. Las mismas etapas morfológicas se encuentran en los animales jóvenes, mientras que algunas etapas adultas se han encontrado en animales inmaduros entre las espermatogonias primarias o secundarias. Etapas similares en el desarrollo espermático se encontraron las descritas para M. manazo, M. griseus y otros elasmobranquiosThe testicles of Mustelus schimitti from a temperate estuary in the South Western Atlantic have a diametric development in which round-shaped spermatocysts show a zonal arrangement. Each zone had spermatocysts containing germ cells in a single development phase. Adult specimens showed six different stages from spermatogonia to mature sperm. The same morphological stages were found in young animals, while some adult stages have been found in immature animals among the spermatogonia, whether primary or secondary. Spermatic stages were found in similar sequences as described for M. manazo, M. griseus and other elasmobranchs.Fil: Rojas, Fernando Oscar. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Bahía Blanca. Instituto Argentino de Oceanografía (i); Argentin

Revisión de la distribución geográfica del genero Cyrtograpsus en Argentina

El género Cyrtograpsus, constituye un género exclusivamente marino, el cual se encuentra representado por cuatro especies hasta la fecha endémicas para Sudamérica. Estos cangrejos en su mayoría son de tamaño pequeño a mediano con respecto a otros miembros de la misma familia son de vital importancia en los ecosistemas costeros donde habitan. Este trabajo presenta una revisión del género respecto a su distribución geográfica, su representación en Argentina, caracterización de los hábitat, ecología, etc.Fil: Rojas, Fernando Oscar. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Bahía Blanca. Instituto Argentino de Oceanografía (i); Argentina. Universidad Nacional del Sur. Departamento de Biología, Bioquímica y Farmacia; Argentin

Evaluation of an acoustic detection algorithm for reactive collision avoidance in underwater applications

Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2013.Cataloged from PDF version of thesis.Includes bibliographical references (page 33).This thesis sought to evaluate a vehicle detection algorithm based on a passive acoustic sensor, intended for autonomous collision avoidance in Unmanned Underwater Vehicles. By placing a hydrophone at a safe distance from a dock, it was possible to record the acoustic signature generated by a small motor boat as it navigated towards, and then away from the sensor. The time-varying sound intensity was estimated by Root Mean Square of the sound amplitude in discrete samples. The time-derivative of the sound intensity was then used to estimate the time to arrival, or collision, of the acoustic source. The algorithm was found to provide a good estimate of the time to collision, with a small standard deviation for the projected collision time, when the acoustic source was moving at approximately constant speed, providing validation of the model at the proof-of-concept level.by Oscar Alberto Viquez Rojas.S.B

¿Las zonas francas, son una opción para America Latina?

En ensayo se hará el análisis del comportamiento de algunas Zonas francas específicas en países de Latino América como Colombia, Costa Rica, Republica Dominicana, Brasil y México lograremos entender el verdadero impacto y si realmente son motor de desarrollo. Por otro lado se observan grandes casos de Zonas Francas de Países como el caso en Malasia donde ha logrado compaginar toda una región completa para el desarrollo de una Zona Franca y el caso de China. Esto con el fin de llegar a evaluar si realmente es el camino a seguir por los países en vía de desarrollo o si es otra estrategia de las grandes multinacionales para disminuir sus costos y arrasar con cuanto encuentren en su camin

Wetting of Nematic Liquid Crystals on Crenellated Substrates: A Frank–Oseen Approach

We revisit the wetting of nematic liquid crystals in contact with crenellated substrates, studied previously using the Landau–de Gennes formalism. However, due to computational limitations, the characteristic length scales of the substrate relief considered in that study limited to less than 100 nematic correlation lengths. The current work uses an extended Frank–Oseen formalism, which includes not only the free-energy contribution due to the elastic deformations but also the surface tension contributions and, if disclinations or other orientational field singularities are present, their core contributions. Within this framework, which was successfully applied to the anchoring transitions of a nematic liquid crystal in contact with structured substrates, we extended the study to much larger length scales including the macroscopic scale. In particular, we analyzed the interfacial states and the transitions between them at the nematic–isotropic coexistence

El Perú desde 1990: El fin de la restricción externa

The main purpose of this paper is to emphasize the importance of the externa1 imbalances generated by the economic program of the Fujimori government, presenting the circumstances that explain why these imbalances have been accompanied, paradoxically, by a significative increase in foreign reserves. With this purpose in mind, two alternative explanations of exchange overvaluation and the implications of the dollarization of bank deposits are discussed. It is then argued that the "temporary withdrawal" of Peru from the Andean Group can be seen as another manifestation of the seriousness of the country's external imbalances, and, finally, the fiscal consequences of the way in which the commercial liberalization has been carried out are discussed.

Impact of nitrogen fertilization on guinea grass (Panicum maximum, Jacq) in the humid premountain forest in the Department of Tolima.

P?ginas 17-21El objetivo del trabajo de investigaci?n fue evaluar la respuesta de diferentes dosis (0, 100, 150 y 300 kg/ha) de nitr?geno en la producci?n de pasto guinea (Panicum maximum, Jacq). Los resultados servir?n para establecer una recomendaci?n t?cnico-econ?mica viable de fertilizaci?n para la producci?n de esta gram?nea bajo condiciones de bosque h?medo sub-andino. El dise?o experimental utilizado fue bloques completos al azar con las cuatro dosis de nitr?geno mencionadas. Se aplic? 246 y 60 kg ha/a?o de CaCO3 y K2 O, respectivamente para correcci?n del pH. La producci?n y el porcentaje de materia seca en el forraje fueron medidos en los tres cortes realizados a intervalos de 28 d?as. Los cortes presentaron efecto significativo (P<0,01) en la producci?n y porcentaje de materia seca. La mayor producci?n de materia seca se encontr? en el corte dos (56 d?as) con 0,23 kg/m2 y el m?ximo porcentaje de MS se encontr? en el corte tres (84 d?as) con 21,4%; mientras que la fertilizaci?n de 300 kg N/ha/a?o present? el mayor rendimiento productivo de la gram?nea. La mayor rentabilidad financiera fue encontrada en el testigo (0 kg N/ha/a?o).ABSTRACT. The goal of this study was to evaluate different levels of nitrogen fertilization (0, 100, 150 and 300 kg/ha/year) on the production of Guinea grass (Panicum maximum). The results should support a viable technical-economical recommendation of fertilization for the production of this grass under sub-Andean humid forest conditions. An experimental design of randomized blocks was used, with four treatments of nitrogen fertilization. It was also applied to all plots 246 and 60 kg/ha/yearof CaCO3 and K2O as pH corrective inputs. The production and percentage of dry mater were evaluated in all three cuttings, which were carried out every 28 days. The cutting presented a significant effect (P<0.01) in the production and percentage of dry matter. The highest dry matter production was found in the second cutting (56 days) with 0.23 kg/m2; and the highest dry matter percentage was found in the third cutting (84 days) with 21%; whereas, the fertilization with 300kg N/ha/year showed the highest grass productivity. The greatest financial profitability was found in the control treatment (0 kg N/ha/year)

GovernIT: A Software for Decision-making Support on Automated IT Governance Models

We developed a software tool named GovernIT to support the creation and evolution of computer-driven Information Technology (IT) governance models. This software automates the design of decision-making grants to coordinate interactions among IT units. It also allows the assessment of business drivers and IT risks to automate the generation of implementation roadmaps for decision-support mechanisms. The software has been used by students of an IT Governance Course to assess undesirable IT behaviors for 21 organizations, to design their target IT governance model, and to generate their IT process implementation roadmap. The results of this implementation evidences the positive impact of dynamic governance models on IT risks and efficiency