Institutional Uncertainty at Home and Away: The Case of Lemons from Argentina

Resource /Energy Economics and Policy, F13, Q17, Q18,

Economic Evaluation of SPS Regulations: Where Can Progress be Made?

The purpose of this paper is to report on the current state of economic evaluations for sanitary and phytosanitary (SPS) regulations affecting food and agricultural trade. The paper reviews current theoretical and econometric advances and limitations in modeling SPS regulations, particularly in dealing with biological and environmental uncertainty. By systematizing limitations of current approaches for evaluation, and comparing them with approaches used in the public health arena, the paper identifies problematic areas, and suggests steps for immediate analytical and policy progress.

Hacia un peifil de la poética nativista argentina.

Sin resume

Early pregnancy diagnosis and embryo/fetus mortality in cattle

Pregnancy diagnosis by transrectal ultrasonography (using a 5 MHZ linear probe) presented the maximum sensitivity and negative predictive values at day 26 and day 29 after estrus in heifers and cows, respectively. Palpation per rectum using the fetal membrane slip for pregnancy diagnosis did not increase embryo/fetus mortality when compared with a positive control group of non-palpated females. The use of a controlled randomized block design was a useful approach to study this problem. Blocking for category and number of embryos allowed us to remove these confounding factors. Factors that affected pregnancy loss during the first four months of pregnancy were: period of pregnancy, age of the animal, number of previous lactations and number of embryos. Pregnancy loss was higher during the embryonic than fetal periods. Spontaneous embryo/fetal mortality increased with the age of the animal and lactation number. The risk of spontaneous embryo/fetus mortality was higher in twin than in single pregnancies. Two types of embryo/fetus mortality were noted: Type I and Type II. Type I was characterized by presence of positive fetal membrane slip by palpation per rectum, signs of degeneration by transrectal ultrasonography and persistence of a functional corpus luteum. The uterus took approximately 3 weeks to be noted clean by transrectal ultrasonography and the animals showed estrus one month after the conceptus was diagnosed dead. Type II was characterized by absence of positive signs of pregnancy by palpation per rectum, absence of signs of degeneration by transrectal ultrasonography and absence of a functional corpus luteum. Pregnancy loss in nuclear transfer derived embryos was higher compared to in vivo derived embryos produced by artificial insemination. Pregnancy loss occurred mainly during the transition from the embryonic to the fetal period. Embryo/fetus mortality detected was Type I. Progesterone produced by the corpus luteum was noted at pregnancy levels for approximately two weeks after embryo/fetus death. Protein B, a hormonal placental marker, was maintained at pregnancy levels for approximately 3 weeks after embryo/fetus death. No differences in the levels of the two hormones were noted when comparing females with dead or live conceptuses

Application of a Natural Language Interface to the Teleoperation of a Mobile Robot

IFAC Intelligent Components for Vehicles, Seville, Spain, 1998This paper describes the application of a natural language interface to the teleoperation of a mobile robot. Natural language communication with robots is a major goal, since it allows for non expert people to communicate with robots in his or her own language. This communication has to be flexible enough to allow the user to control the robot with a minimum knowledge about its details. In order to do this, the user must be able to perform simple operations as well as high level tasks which involve multiple elements of the system. For this ones, an adequate representation of the knowledge about the robot and its environment will allow the creation of a plan of simple actions whose execution will result in the accomplishment of the requested tas

Modelagem e validação experimental de um atuador baseado em liga de memória de forma

As ligas com memória de forma (Shape Memory Alloy - SMA) consistem em um grupo de materiais metálicos que possuem a habilidade de retornar a um formato ou tamanho previamente definido quando submetidas a um ciclo térmico adequado. Os efeitos de memória de forma ocorrem devido a mudanças na estrutura cristalina do material, dependentes da temperatura e da tensão ao qual está sujeito. A fase de Martensita, estado presente a baixas temperaturas, apresenta comportamento plástico, com maior facilidade para deformações permanentes. A fase de Austenita, que ocorre a altas temperaturas, apresenta comportamento elástico com alta rigidez. A mudança na estrutura cristalina do material não é um processo termodinamicamente reversível, apresentando, conseqüentemente, histerese. Portanto, a característica principal destes materiais é a habilidade de sofrer grandes deformações plásticas e, em seguida, recuperar sua forma original quando a carga é removida ou o material é aquecido. Assim, pode-se utilizar esse fenômeno para construir atuadores leves e silenciosos, como verdadeiros músculos metálicos. O desenvolvimento de atuadores com as SMAs apresenta grande atrativo para diversos campos da engenharia, principalmente na área de robótica, substituindo os atuadores convencionais de grande peso e ruidosos, como motores, válvula solenóides, etc. Entretanto, para o bom desempenho de atuadores SMA requer-se um complexo sistema de controle e resfriamento, reduzindo-se o tempo de resposta do atuador e minimizando-se os efeitos da histerese. Nesse trabalho, propõe-se um inovador sistema de resfriamento, baseado em pastilha termo-elétrica (efeito Seebeck-Peltier). Este método possui a vantagem de ser mais compacto e simples que outros métodos de resfriamento forçado. Um modelo matemático completo é também desenvolvido, e um protótipo experimental foi construído. Diversos experimentos foram utilizados para a validação do modelo e para a identificação de todos seus parâmetros. Em um próximo trabalho, um sistema de controle será desenvolvido e implementado no protótipo, baseado no modelo matemático ora proposto.Shape Memory Alloys (SMA) consist of a group of metallic materials that demonstrate the ability to return to some previously defined shape when subjected to the appropriate thermal procedure. The shape memory effect occurs due to a temperature and stress dependent shift in the materials crystalline structure between two different phases. Martensite, the low temperature phase, is relatively soft whereas Austenite, the high temperature phase, is relatively hard. The change that occurs within SMAs crystalline structure is not a thermodynamically reversible process and results in temperature hysteresis. The key feature of these materials is the ability to undergo large plastic strains and subsequently recover these strains when a load is removed or the material is heated. Such property can be used to build silent and light actuators, similar to a mechanical muscular fiber. SMA actuators have several advantages in several engineering fields, mainly in robotics, replacing the conventional actuators like motors or solenoids. However, the good performance of the SMA actuator depends on a complex control and cooling systems, reducing the time constant and minimizing the effects of hysteresis. In the present paper, a novel cooling system is proposed, based on thermo-electric effect (Seebeck-Peltier effect). Such method has the advantage of reduced weight and requires a simpler control strategy compared to other forced cooling systems. A complete mathematical model of the actuator is also derived, and an experimental prototype was implemented. Several experiments were used to validate the model and to identify all parameters. In a next work, a control system will be developed and implemented in the prototype, based on the mathematical model here exposed

¿De dónde surgieron los “nuevos lectores” argentinos, a mediados del siglo XX?

En este artículo, donde se intenta dar respuesta a la pregunta del título (“¿De dónde surgieron los “nuevos lectores” argentinos, a mediados del siglo XX?”), se señala la decisiva intervención de distintas publicaciones, prioritariamente las revistas ilustradas rioplatenses (en el ejemplo de Caras y Caretas) y la colección La novela semanal, ambos formatos y por distintos motivos impulsores de un nuevo lectorado por fuera de las élites. Dentro del estudio se atiende asimismo a la polémica dentro del campo intelectual entre las teorías “alternativistas” de la dependencia y la valoración de estas textualidades populares en su legitimidad simbólica y sus resistencias y negociaciones con las hegemonías

Trayectoria intelectual de Ricardo Rojas 1901-1917

Ricardo Rojas’s (1901-1957) first stage of the intellectual itinerary extends from the end of the 19th century until 1917, from his first publication in Buenos Aires (a short story in Caras y Caretas, 1901) to the first volume of his founder Historia de la literature argentina. In this period, Rojas shows at least two embryonic poetics. With his articles on El País of Carlos Pellegrini and especially the ones on Libre Palabra, as well as some of his reviews –a in particular the one dedicated to Pérez Galdós’ Electra– a liberal reformism surrounding the socialists, which explains his excellent relationship with Nosotros magazine since it was founded in 1907. El país de la selva (1907), Cartas desde Europa (1907-1908), Cosmópolis (1909) Blasón de Plata (1910), La Argentinidad (1916) show some resonances, the line of nativism predominates as we advance in this way that leads into his HIstoria…, where knowledge from different fields(geology, anthropology, philology, folklore, history, etc.) can be found to merge national literature and culture.Una primera etapa de la trayectoria intelectual de Ricardo Rojas (1901-1957) se extiende desde fines del siglo XIX hasta 1917, es decir desde su primera publicación en Buenos Aires (un cuento para Caras y Caretas, en 1901) hasta el primer tomo de su fundadora Historia de la literatura argentina. En ese lapso, adhiere por lo menos a dos poéticas en proceso de gestación. Con sus artículos periodísticos de El país de Carlos Pellegrini y sobre todo los de Libre Palabra, así como algunas de sus críticas –en especial la dedicada al estreno de Electra de Pérez Galdós- a un reformismo liberal cercano al de los socialistas, lo que explica su excelente relación con la revista Nosotros desde que fuera fundada (1907). En El país de la selva (1907), las Cartas desde Europa (1907-1908), Cosmópolis (1909) Blasón de Plata (1910), La Argentinidad (1916) hay resonancias de las mismas, aunque la veta nativista predomina a medida que avanzamos en ese trayecto que desemboca en su Historia..., donde apela a diversos saberes (geología, antropología, filología, folklore, historia, etc.) para engarzar literatura y cultura nacionales