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Search Results: 1 - 10 of 5388 matches for " Gonzalo Rubio "
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The Effects of Systemic Risk on the Allocation between Value and Growth Portfolios  [PDF]
Gabriel Penagos, Gonzalo Rubio
Journal of Mathematical Finance (JMF) , 2013, DOI: 10.4236/jmf.2013.31A016
Abstract:

Given the striking effects of the recent financial turmoil, and the importance of value and growth portfolios for both local and international portfolio allocation, we investigate the effects of systemic jumps on the optimal portfolio investment strategies across value and growth equity portfolios. We find that the cost of ignoring systemic jumps is not substantial, unless the portfolio is highly levered and the average size amplitude of the jump is large enough. From the optimal asset allocation point of view, it seems more important the effects of few but relatively large jumps than highly frequent but small jumps. Indeed, the period in which the value premium is higher coincides with a period of few, but large and positive average size jumps for value stocks, and negative and very large average size jumps for growth stocks.


Portfolio choice and the effects of liquidity
Ana González,Gonzalo Rubio
SERIEs , 2011, DOI: 10.1007/s13209-010-0025-4
Abstract: This paper discusses how to introduce liquidity into the well known mean-variance framework of portfolio selection using a representative sample of Spanish equity portfolios. Either by estimating mean-variance liquidity constrained frontiers or directly estimating optimal portfolios for alternative levels of risk aversion and preference for liquidity, we obtain strong effects of liquidity on optimal portfolio selection. In particular, portfolio performance, measured by the Sharpe ratio relative to the tangency portfolio, varies significantly with liquidity. When the investor shows no preference for liquidity, the performance of optimal portfolios is relatively more favorable. However, it is also the case that, under no preference for liquidity, these portfolios display lower levels of liquidity. Finally, we also study how the aggregate level of illiquidity affects optimal portfolio selection.
Orb-weaving spider diversity in the Iberá Marshlands, Argentina
Rubio, Gonzalo D;Moreno, Claudia E;
Neotropical Entomology , 2010, DOI: 10.1590/S1519-566X2010000400006
Abstract: the iberá marshlands ramsar reserve, in the northeast of argentina, is one of the largest and most important wetlands of america. in this study we assess orb-weaving spider (araneae: orbiculariae) diversity in this reserve, analyzing different facets of local diversity (species richness, diversity, evenness and taxonomic distinctness), and the contribution of species differentiation (beta diversity) among localities and habitat types to the composition of regional diversity. we found 1657 individuals of 59 orb-weaving spider species/morphospecies. local diversity differs among the three sampled localities. at the habitat level, the different facets of biodiversity followed a clear pattern, where woodlands have higher species richness, diversity, evenness and taxonomic distinctness than savannas. savanna sites shared a common spider species composition, while woodland communities have high values of complementarity. thus, beta diversity has a very high contribution to the regional diversity of the orb-weaving spiders in the iberá marshlands. we suggest that conservation management in the reserve should be directed towards promoting natural spatial heterogeneity, giving special protection to habitat mosaics in different localities.
OPTIMIZACION DE UNA TECNICA DE MUESTREO IN SITU: ANáLISIS DE Cu Y Fe EN SISTEMAS ACUáTICOS
PIZARRO,JAIME; RUBIO,M. ANGELICA; LIRA,GONZALO;
Boletín de la Sociedad Chilena de Química , 2001, DOI: 10.4067/S0366-16442001000300007
Abstract: the improvement of the technique of diffusive gradients in thin layers (dgt) and the sampling have been tested for cu and fe ions in two different samples: synthetic (solution) and heterogeneous (sediment-water interface). both analytical determinations showed low relative error and low standard deviation. gel preparation, assembly dgt device, thickness diffusive layer (0.45 mm), time sampling (6 h), time elution (18) , and elution factor (fe: 0.79 ± 0.02; cu: 0.80 ± 0.04) were optimized
The first Symphytognathidae (Arachnida: Araneae) from Argentina, with the description of a new species of Anapistula from the Yungas mountain rainforest
RUBIO,GONZALO D; GONZáLEZ,ALDA;
Revista chilena de historia natural , 2010, DOI: 10.4067/S0716-078X2010000200005
Abstract: the spider family symphytognathidae is reported from argentina for the first time. anapistula yungas, a new species of this family is described and illustrated. the specimen was collected during an ecological study of biodiversity in different sites from northwestern argentina. dichotomous key to neotropical female species of genus anapistula is provided.
The first Symphytognathidae (Arachnida: Araneae) from Argentina, with the description of a new species of Anapistula from the Yungas mountain rainforest La primera Symphytognathidae (Arachnida: Araneae) para Argentina, con la descripción de una nueva especie de Anapistula para la selva de monta a Yungas
GONZALO D RUBIO,ALDA GONZáLEZ
Revista chilena de historia natural , 2010,
Abstract: The spider family Symphytognathidae is reported from Argentina for the first time. Anapistula yungas, a new species of this family is described and illustrated. The specimen was collected during an ecological study of biodiversity in different sites from northwestern Argentina. Dichotomous key to Neotropical female species of genus Anapistula is provided. La familia de ara as Symphytognathidae es registrada por primera vez en Argentina. Anapistula yungas, una nueva especie de esta familia, es descripta e ilustrada. Los especímenes fueron colectados durante un estudio ecológico de biodiversidad en diferentes sitios del noroeste de Argentina. Se proporciona una clave dicotómica para hembras de las especies neotropicales del género Anapistula.
OPTIMIZACION DE UNA TECNICA DE MUESTREO IN SITU: ANáLISIS DE Cu Y Fe EN SISTEMAS ACUáTICOS
JAIME PIZARRO,M. ANGELICA RUBIO,GONZALO LIRA
Boletín de la Sociedad Chilena de Química , 2001,
Abstract: Se hicieron ensayos con la técnica de gradiente de difusión en capa fina (DGT) y de muestreo. ésta se aplicó en la determinación de Cu y Fe en dos medios distintos: sintético (solución) y heterogéneo (interfaz sedimento-agua). Ambas determinaciones analíticas mostraron un bajo error relativo y estándar. Se optimizó la preparación de geles, montaje del dispositivo DGT, grosor de la capa de difusión (0,45 mm), tiempo de muestreo (6 h), tiempo de elusión (18 h) y factor de elusión (Fe: 0.79 ± 0.02; Cu: 0.80 ± 0.04) The improvement of the technique of diffusive gradients in thin layers (DGT) and the sampling have been tested for Cu and Fe ions in two different samples: synthetic (solution) and heterogeneous (sediment-water interface). Both analytical determinations showed low relative error and low standard deviation. Gel preparation, assembly DGT device, thickness diffusive layer (0.45 mm), time sampling (6 h), time elution (18) , and elution factor (Fe: 0.79 ± 0.02; Cu: 0.80 ± 0.04) were optimized
Aspectos ecológicos de Aglaoctenus lagotis (Araneae: Lycosidae) con énfasis en la preferencia de hábitat. Corrientes, Argentina Ecological aspects of Aglaoctenus lagotis (Araneae: Lycosidae) with emphasis in preference of habitat. Corrientes, Argentina
GONZALO D RUBIO,ESTEBAN I MEZA T,GILBERTO áVALOS
Revista Colombiana de Entomología , 2005,
Abstract: Se analizaron algunos aspectos ecológicos de Aglaoclenus lagotis Holmberg, principalmente su presencia en las especies vegetales Aechmea distichantha Lem. y Bromelia serra Lem. (Bromeliaceae). El estudio se adelantó en la localidad de Laguna Brava. Provincia de Corrientes. Argentina. Se utilizó el método de muestreo por bandeado y registro (taxiado) a lo largo de dos transectos de 300 meada uno. Se encontraron 162 especímenes de A. lagoris sobre un total de 650 Bromelias examinadas. La prueba de comparación de dos proporciones e índice de clectividad comprobó una notable preferencia de las ara as por los rosetones deA. distichuniha. ubicados en el bosque y expuestos a baja intensidad lumínica. Se determinó que el 38,2% dela población deA. distichantha está habitada por A. lagotis. y el 4.3% dela población de B. serra se halló con el mismo tipo de relación. Es menester realizar estudios comparativos en diferentes localidades, a efectos de verificar la presencia de esta ara a en otros géneros de bromeliáceas como Vriesea. Bilihergia y Pseudananas.
Growth effort of Sceloporus scalaris (Sauria: Phrynosomatidae) at La Michilía Biosphere Reserve, Mexico
Alfredo Ortega-Rubio,Robert Barbault,Gonzalo Halffter,Aradit Castellanos
Revista de Biología Tropical , 1998,
Abstract: Using Mark-Recapture methods the growth effort of Sceloporus scalaris was studied at La Michilìa Biosphere Reserve, Durango, Mexico. A total of 146 recaptures on 68 individuals were obtained over four years on a 50 000 m 2 transect. To calculate the growth rate of Sceloporus scalaris individuals, we analyzed the data from two sources. The first using the recapture records of the same individuals over different seasons and the second using the records of cohorts during different periods. The growth effort of S. scalaris drastically diminishes as the organism grows. The growth rate of males and females is about equal for individuals from both clutches. In adults, where it is possible to compare among seasons, we measure quicker growth during the spring. The growth pattern of S. scalaris at La Michilìa follows the predictions proposed by the Bertalanffy model. Maximum growth rates are in the younger age classes and these rates decrease as size increases. The growing period of S. scalaris is correlated with the seasons at La Michilìa Biosphere Reserve. Newborn S. scalaris appear when the availability of nourishment is still the most propitious for growth at faster rates. Such adaptations to the environment determine many key population attributes of this species in this zone. The sexual maturity age of S. scalaris is very early at La Michilìa, only 4.5 to 6 months. Undoubtedly, the growth pattern of S. scalaris at La Michilìa Biosphere Reserve can help explain the structure and dynamics of this population. Usando métodos de Marca-Recaptura estudiamos el esfuerzo de crecimiento de Sceloporus scalaris en la Reserva de la Biosfera de La Michilìa, Durango, México. Se analizaron 146 registros de recaptura sobre 68 individuos en cuatro a os de estudio en un transecto de 50 000 m2. El esfuerzo de crecimiento disminuye drasticamente conforme el individuo crece, es casi igual para los machos y hembras de las dos puestas, y en el caso de los adultos se registró un crecimiento más rápido en primavera. El patrón de crecimiento sigue las predicciones propuestas por el modelo de Bertalanffy. Los recién nacidos de S. scalaris eclosionan cuando la disponibilidad de alimento es todavìa la m·s propicia. La madurez sexual de los individuos es muy precoz en La Michilía: de 4.5 a 6 meses. El patrón de crecimiento de S. scalaris en La Michilía ayuda a explicar la estructura y dinámica de esta población.
Tilt Table Test: State of The Art
Gonzalo Barón-Esquivias,Antoni Martínez-Rubio
Indian Pacing and Electrophysiology Journal , 2003,
Abstract: The loss of consciousness has been a subject of wonder and uncertainty in humans, and for this reason it has been the object of medical investigation since the beginning of time. Even actually, it is certainly an unresolved clinical problem. Many centuries ago, complicated exorcisms and remedies were used on these unfortunate patients, who upon regaining consciousness would find themselves soaked in miraculous liquids, ingesting curative potions, and often on the way to be burned accused of being possessed. In the seventeen century, physicians began to relate loss of consciousness and haemodinamic changes. William Harvey was perhaps the first to describe a circulatory response (vasovagal reaction) during a phlebotomy in the year 1628: ...Yet it fear or any other cause, or something do intervene through passion of the mind, so that the heart do beat more faintly, the blood will be no means pass through but drop after drop 1. During the nineteenth century, loss of consciousness was the object of studies and research, and the vagally mediated cardioinhibition, as a primary cause, was noted by Foster who proposed that profound bradycardia diminished cerebral perfusion to a level inadequate to maintain consciousness2. At this time, it was reported the first use of the tilt-table test3. Commonly referred to as fainting or loss of consciousness, from last century the preferred medical term is syncope, which itself is derived from the Greek term syncoptein meaning to cut short . Syncope is defined as the sudden loss of consciousness and postural tone with spontaneous recovery. In 1907, Gowers was the first person to use the term vasovagal syncope4. In 1918 was published the work in which Cotton and Lewis described for the first time the clinical characteristics that are still used today to recognize the syncopal reaction5. However, it was not till 1932 when Lewis described this reaction as being characterized by a combination of bradycardia, hypotension, and syncope, and he coined the term vasovagal syncope for the first time6.
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