Stochastic volatility models and the Taylor effect

It has been often empirically observed that the sample autocorrelations of absolute financial returns are larger than those of squared returns. This property, know as Taylor effect, is analysed in this paper in the Stochastic Volatility (SV) model framework. We show that the stationary autoregressive SV model is able to generate this property for realistic parameter specifications. On the other hand, the Taylor effect is shown not to be a sampling phenomena due to estimation biases of the sample autocorrelations. Therefore, financial models that aims to explain the behaviour of financial returns should take account of this property

Optimizing electron backscatter diffraction of carbonate biominerals—resin type and carbon coating

Electron backscatter diffraction (EBSD) is becoming a widely used technique to determine crystallographic orientation in biogenic carbonates. Despite this use, there is little information available on preparation for the analysis of biogenic carbonates. EBSD data are compared for biogenic aragonite and calcite in the common blue mussel, <i>Mytilus edulis</i>, using different types of resin and thicknesses of carbon coating. Results indicate that carbonate biomineral samples provide better EBSD results if they are embedded in resin, particularly epoxy resin. A uniform layer of carbon of 2.5 nm thickness provides sufficient conductivity for EBSD analyses of such insulators to avoid charging without masking the diffracted signal. Diffraction intensity decreases with carbon coating thickness of 5 nm or more. This study demonstrates the importance of optimizing sample preparation for EBSD analyses of insulators such as carbonate biominerals

Viability study of sailing propulsion combined with a conventional system

For many years now, sails have been used as a propulsion system. At present, they are restricted to recreational/sport crafts since the appearance of the first steam vessels in the beginning of the 19 th century. But in the last years, due to the increase of fuel price and the pollution of the environment, it is being studied the possibility to introduce again the sail as a propulsive method combined with other conventional systems. In this paper, it is studied the viability of using a sail as a propellant with other conventional systems of propulsion. After considering the concept of apparent wind, the range of use of this complementary propulsion is presented. The calculation methodology, the numerical simulations and the wind inputs from a specific route are also included

Single-random phase encoding architecture using a focus tunable lens

We propose a new nonlinear optical architecture based on a focus tunable lens and an iterative phase retrieval algorithm. It constitutes a compact encryption system that uses a single-random phase key to simultaneously encrypt (decrypt) amplitude and phase data. Summarily, the information encoded in a transmittance object (phase and amplitude) is randomly modulated by a diffuser when a laser beam illuminates it; once the beam reaches a focus tunable lens, different subjective speckle distributions are registered at some image plane as the focal length is tuned to different values. This set of speckle patterns constitutes a delocalized ciphertext, which is used in an iterative phase retrieval algorithm to reconstruct a complex ciphertext. The original data are decrypted propagating this ciphertext through a virtual optical system. In this system, amplitude data are straightforwardly decrypted while phase data can only be restored if the random modulation produced in the encryption process is compensated. Thus, an encryption-decryption process and authentication protocol can simultaneously be performed. We validate the feasibility of our proposal with simulated and experimental results.Fil: Mosso Solano, Edward Fabian. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Pontificia Universidad Católica de Valparaíso; ChileFil: Bolognini, Nestor Alberto. Universidad Nacional de La Plata. Facultad de Ciencias Exactas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigaciones Ópticas. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Centro de Investigaciones Ópticas. Universidad Nacional de La Plata. Centro de Investigaciones Ópticas; ArgentinaFil: Pérez, D.G.. Pontificia Universidad Católica de Valparaíso; Chil

Drosophila melanogaster mutant tan

Drosophila melanogaster gene tan was originally discovered in the early 20th century as a mutant strain lacking the dark pi gment pattern of wild-type (wt) f lies and, therefore, showing a light yellowish brown color (McEwen, 1918). Flies lack ing Tan function also exhibited abnormalities in vision (Benzer, 1967; Inoue et al. , 1988; True et al. , 2005), and tan males displayed an abnormal courtship behavior (Cook, 1980; Tomkins et al. , 1982). tan 1 ( t 1 ) and tan 3 ( t 3 ) alleles were found as spontaneous mutations, t 3 mutant being apparently lighter than t 1 (Brehme, 1941). tan is the structural gene for N- β -alanyldopamine hydrolase (NBAD-hydrolase or Tan protein), the enzyme that generates dopamine (DA) from NBAD (Wright, 1987; True et al. , 2005). Tan is expressed as a precursor protein of 43.7 kDa. Th is precursor is clea ved into two subunits of 29.9 and 13.8 kDa that apparently conform together a he terodimeric active protein (Wagner et al. , 2007). The enzyme that generates NBAD from DA, th e opposite reaction to the one catalyzed by Tan, is the NBAD-synthase or E bony protein (Wright, 1987; Pérez et al ., 1997), which is codified by the gene ebony . Since both Tan and Ebony ar e involved in cuticle tanni ng, carcinine re gulation, and NBAD metabolism in nervous tissue (Wright, 1987; Pérez et al. , 1997, 2004; Hovemann et al. , 1998; Borycz et al. , 2002; True et al. , 2005), it has been suggested that they function together in a system regulating the levels of dopamine during cuticle sclerotization a nd histamine in the visual metabolism (Borycz et al. , 2002; Pérez et al. , 2010). During the last few years, several publicati ons appeared regarding NBAD-synthase (Wappner et al ., 1996a, b; Pérez et al ., 1997, 2002, 2004, 2010; Hovemann et al. , 1998; Borycz et al. , 2002; Wittkopp et al., 2002; Schachter et al ., 2007), but very little is known about tan (True et al. , 2005; Wagner et al. , 2007). Thus, it was important to furthe r characterize the NBAD-hydrolase in D. melanogaster wt and in mutants t 1 and t 3.Fil: Badaracco, Alejandra. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Bioquímicas de Buenos Aires. Fundación Instituto Leloir. Instituto de Investigaciones Bioquímicas de Buenos Aires; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Química Biológica de la Facultad de Ciencias Exactas y Naturales. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Química Biológica de la Facultad de Ciencias Exactas y Naturales; ArgentinaFil: Quesada Allue, Luis Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Bioquímicas de Buenos Aires. Fundación Instituto Leloir. Instituto de Investigaciones Bioquímicas de Buenos Aires; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Química Biológica de la Facultad de Ciencias Exactas y Naturales. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Química Biológica de la Facultad de Ciencias Exactas y Naturales; ArgentinaFil: Pérez, Martín Mariano. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Bioquímicas de Buenos Aires. Fundación Instituto Leloir. Instituto de Investigaciones Bioquímicas de Buenos Aires; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Química Biológica de la Facultad de Ciencias Exactas y Naturales. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Química Biológica de la Facultad de Ciencias Exactas y Naturales; Argentin

Gelman y la poesía norteamericana : Los poemas de Sidney West

En la década del sesenta Juan Gelman decidió ensayar otras voces poéticas y ser "traductor" de poetas de otras culturas. Si Leónidas Lamborghini escoge el canto paralelo, la para-oda, la parodia, para distanciarse críticamente (y homenajear) a la poesía nacional, Juan Gelman intenta sumergirse en la subjetividad de poesía rebelde y contestataria norteamericana e imaginar un poeta posible, Sidney West. El género elegido es el lamento, la elegía. Sus personajes son seres rechazados por su cultura, poetas incomprendidos en una sociedad materialista y consumista, que ignora la sensibilidad del poeta y hace de él su víctima. La mirada de Gelman es doble: es una visión de la poesía rebelde norteamericana de los sesenta, y una crítica al capitalismo materialista y al imperialismo destructor. Valiéndose de la ficción de ser el poeta norteamericano Sidney West escapa de la autocensura para liberar su propia imaginación en una poesía elegíaca exaltada, que es a la vez trágica y cómica, lírica y crítica. En mi trabajo analizaré este libro de Gelman, en relación al resto de su obra y a la poesía argentina de la décad

Grid Global Behavior Prediction

Complexity has always been one of the most important issues in distributed computing. From the first clusters to grid and now cloud computing, dealing correctly and efficiently with system complexity is the key to taking technology a step further. In this sense, global behavior modeling is an innovative methodology aimed at understanding the grid behavior. The main objective of this methodology is to synthesize the grid's vast, heterogeneous nature into a simple but powerful behavior model, represented in the form of a single, abstract entity, with a global state. Global behavior modeling has proved to be very useful in effectively managing grid complexity but, in many cases, deeper knowledge is needed. It generates a descriptive model that could be greatly improved if extended not only to explain behavior, but also to predict it. In this paper we present a prediction methodology whose objective is to define the techniques needed to create global behavior prediction models for grid systems. This global behavior prediction can benefit grid management, specially in areas such as fault tolerance or job scheduling. The paper presents experimental results obtained in real scenarios in order to validate this approach