On the mean-standard deviation frontier

This paper presents a characterization of the mean standard deviation frontier (MSF) in terms of pricing and averaging securities and explores the geometry of these securities relative to the geometry of the MSF. A summary of already known results is presented along with proof of new results. A measure of the distance between two mean standard deviation frontiers is presented here. This measure is related to asset pricing models which imply that security prices can be represented by a stochastic discount factor, such as the CAPM (Capital Asset Pricing Model) and the APT (Arbitrage Pricing Theory). An application is given in which the distance between two specific frontiers can be interpreted as a measure of model misspecification.

OCT in Applications That Involve the Measurement of Large Dimensions

The application of optical coherence tomography (OCT) technique is not very common when measuring large dimensions is required. This type of measurements can be critical to achieve satisfactory results in the manufacturing process of precision parts. Components and structures ranging from submillimeter to several centimeters size can be found in many fields including automotive, aerospace, semiconductor, and data storage industries to name a few. In this chapter, an interferometric system based on the swept source optical coherence tomography (SS-OCT) technique, which has a wide measurement range and good axial resolution, is presented and its constituent parts are analyzed. The scheme includes a self-calibration stage based on fiber Bragg gratings (FBGs) that allows monitoring the spectral position of the light source in each scan, having the advantage of being a passive system that requires no additional electronic devices. Several applications of the system are described, including measurement of distances up to 17 cm, characterization of multilayer transparent and semitransparent structures, simultaneous determination of thickness of the wall, internal and external diameter of glass ampoules or similar containers, thickness measurements in opaque samples or where the refractive index is unknown, etc

Coeficiente de transmissão de radiação solar em Manaus em junho ()

Global and diffuse solar radiation measurements, obtained by means of an Eppley pyrheliometer, were made two days in June 1975, one was clear day, (June, 11), and the other an overcast day (June, 19). The mean transmission coefficient for global and direct radiation were determined to be 0,81 and 0,70 respectively. The data on daily global solar radiation indicated that the values measured with the actinograph under estimate the real solar radiation values reaching the ground.Medidas de radiação global e difusa foram realizadas com um pirelhiometro Eppley em dois dias característicos, um limpo e outro nublado em junho de 1975. Os valores médios para os coeficientes de transmissão para médias global e direta foram 0,81 e 0,70 respectivamente no dia 11/06/75. Os dados de radiação global diária indicam que os resultados obtidos com actinógrafos instalados na área subestimam o total de energia realmente disponível ao nível do solo

Precipitation In The Central Amazon Basin: - The Isotopic Composition Of Rain And Atmospheric Moisture At Belém And Manaus

In order to improve the understanding of the water in the Amazon Basin, samples of rain and moisture were collected daily at Belém and Manaus from August 78 to January 80. All isotope data are presented. The most depleted values, sometimes lower than - 10‰ in δ18O at Belém or Manaus, were encountered during the rainy season (January-April). Possible causes of the seasonal differences in tne isotope pattern are discussed.No período de agosto de 1978 a janeiro de 1980, foram feitas coletas diárias de amostras de águas de chuva e de vapor d'água do ar em Belém e Manaus, a fim de ampliar os conhecimentos a cerca de parâmetros ligados ao ciclo da água na bacia Amazônica. Estão apresentados os dados isotópicos referentes as amostras. Os valores mais negativos ocorreram durante o período chuvoso (janeiro-abril), atingindo muitas vezes, valores de δ18O menores do que - 10‰. São discutidas as possíveis causas dessas composições.", 'p

Evaluation of the Expression and Protective Potential of Leptospiral Sphingomyelinases

Leptospirosis is a zoonotic disease of global distribution, which affects both animals and humans. Pathogenic leptospires, the bacteria that cause this disease, require iron for their growth, and these spirochetes probably use their hemolysins, such as the sphingomyelinases, as a way to obtain this important nutrient from host red blood cells during infection. We expressed and purified the leptospiral sphingomyelinases Sph1, Sph2, Sph4, and SphH in a heterologous system. However, the recombinant proteins were not able to lyse sheep erythrocytes, despite having regular secondary structures. Transcripts for all sphingomyelinases tested were detected by RT-PCR analyses, but only Sph2 and SphH native proteins could be detected in Western blot assays using Leptospira whole extracts as well as in renal tubules of infected hamsters. Moreover, antibodies present in the serum of a human patient with laboratory-confirmed leptospirosis recognized Sph2, indicating that this sphingomyelinase is expressed and exposed to the immune system during infection in humans. However, in an animal challenge model, none of the sphingomyelinases tested conferred protection against leptospirosis.Instituto de Biotecnología y Biología Molecula

Leptospiral TlyC is an extracellular matrix-binding protein and does not present hemolysin activity

The role of TlyA, TlyB and TlyC proteins in the biology of Leptospira is still uncertain. Although these proteins have been considered as putative hemolysins, we demonstrate that leptospiral recombinant TlyB and TlyC do not possess hemolytic activity. However, further experiments showed that TlyC is a surface-exposed protein that seems to bind to laminin, collagen IV and fibronectin. The expression of both proteins was detected both in vitro and in vivo. Our findings suggest that TlyB and TlyC are not directly involved in hemolysis, and that TlyC may contribute to Leptospira binding to extracellular matrix (ECM) during host infection.Facultad de Ciencias ExactasInstituto de Biotecnologia y Biologia Molecula

Estudio de seroprevalencia de enfermedad de Chagas-Mazza en residentes del Cinturón Hortícola Platense

La Enfermedad de Chagas-Mazza, es silenciosa, frecuentemente ocasiona lesiones sin notables manifestaciones clínicas. Numerosas personas desconocen su condición de afectados por Tripanosoma cruzi. Cuando ellas tienen acceso a diagnósticos clínicos y seroepidemiológicos, puede ocurrir que haga ya muchos años que han sido afectados y haya daños orgánicos. En este estudio se realizaron actividades en territorio, en el cinturón frutihortícola platense en el que habitan personas provenientes de áreas endémicas de Enfermedad de Chagas-Mazza, como parte de un proyecto integral. Con consentimiento informado se realizaron extracciones y diagnósticos. Las personas seropositivas fueron luego estudiadas, seguidas y medicadas según cada caso siguiendo las indicaciones establecidas en los protocolos vigentes consensuados. Ellos no conocían su condición de afectados. Es necesario incrementar las acciones en el territorio a efectos de realizar diagnósticos tempranos y acciones oportunas.Chagas-Mazza disease is silent, frequently causes lesions without manifestations. notable clinical Many people are unaware of their status as affected by Trypanosoma cruzi. When they have access to clinical and seroepidemiological diagnoses, it may happen that they have been affected for years and there is organic damage. In this study, activities were carried out in the territory, in the La Plata fruit and vegetable belt where people from endemic areas of Chagas-Mazza disease live, as part of a comprehensive project. With informed consent, extractions and diagnoses were performed. The seropositive people were then studied, followed up and medicated according to each following the indications established in the current agreed protocols. They did not know their status as affected. It is necessary to increase actions in the territory in order to carry out early and timely actions.Facultad de Ciencias Veterinaria

Alcohol dehydrogenase activities and ethanol tolerance in Anastrepha (Diptera, Tephritidae) fruit-fly species and their hybrids

The ADH (alcohol dehydrogenase) system is one of the earliest known models of molecular evolution, and is still the most studied in Drosophila. Herein, we studied this model in the genus Anastrepha (Diptera, Tephritidae). Due to the remarkable advantages it presents, it is possible to cross species with different Adh genotypes and with different phenotype traits related to ethanol tolerance. The two species studied here each have a different number of Adh gene copies, whereby crosses generate polymorphisms in gene number and in composition of the genetic background. We measured certain traits related to ethanol metabolism and tolerance. ADH specific enzyme activity presented gene by environment interactions, and the larval protein content showed an additive pattern of inheritance, whilst ADH enzyme activity per larva presented a complex behavior that may be explained by epistatic effects. Regression models suggest that there are heritable factors acting on ethanol tolerance, which may be related to enzymatic activity of the ADHs and to larval mass, although a pronounced environmental effect on ethanol tolerance was also observed. By using these data, we speculated on the mechanisms of ethanol tolerance and its inheritance as well as of associated traits

An Analysis of the Myocardial Transcriptome in a Mouse Model of Cardiac Dysfunction with Decreased Cholinergic Neurotransmission

Autonomic dysfunction is observed in many cardiovascular diseases and contributes to cardiac remodeling and heart disease. We previously reported that a decrease in the expression levels of the vesicular acetylcholine transporter (VAChT) in genetically-modified homozygous mice (VAChT KDHOM) leads to decreased cholinergic tone, autonomic imbalance and a phenotype resembling cardiac dysfunction. In order to further understand the molecular changes resulting from chronic long-term decrease in parasympathetic tone, we undertook a transcriptome-based, microarray-driven approach to analyze gene expression changes in ventricular tissue from VAChT KDHOM mice. We demonstrate that a decrease in cholinergic tone is associated with alterations in gene expression in mutant hearts, which might contribute to increased ROS levels observed in these cardiomyocytes. In contrast, in another model of cardiac remodeling and autonomic imbalance, induced through chronic isoproterenol treatment to increase sympathetic drive, these genes did not appear to be altered in a pattern similar to that observed in VAChT KDHOM hearts. These data suggest the importance of maintaining a fine balance between the two branches of the autonomic nervous system and the significance of absolute levels of cholinergic tone in proper cardiac function