748 research outputs found

    Neocortical-hippocampal dynamics of working memory in healthy and diseased brain states based on functional connectivity

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    Working memory (WM) is the ability to transiently maintain and manipulate internal representations beyond its external availability to the senses. This process is thought to support high level cognitive abilities and been shown to be strongly predictive of individual intelligence and reasoning abilities. While early models of WM have relied on a modular perspective of brain functioning, more recent evidence suggests that cognitive functions emerge from the interactions of multiple brain regions to generate large-scale networks. Here we will review the current research on functional connectivity of WM processes to highlight the critical role played by neural interactions in healthy and pathological brain states. Recent findings demonstrate that WM abilities are not determined solely by local brain activity, but also rely on the functional coupling of neocortical-hippocampal regions to support WM processes. Although the hippocampus has long been held to be important for long-term declarative memory, recent evidence suggests that the hippocampus may also be necessary to coordinate disparate cortical regions supporting the periodic reactivation of internal representations in WM. Furthermore, recent brain imaging studies using connectivity measures, have shown that changes in cortico-limbic interactions can be useful to characterize WM impairments observed in different neuropathological conditions. Recent advances in electrophysiological and neuroimaging techniques to model network activity has led to important insights into how neocortical and hippocampal regions support WM processes and how disruptions along this network can lead to the memory impairments commonly reported in many neuropathological populationsThis work was supported by a research grant from the Spanish Ministry of Science and Innovation (Grant PSI2010–16742) to Pablo Campo. Claudia Poch was supported by Spanish Ministry of Science and Education (AP2009–4131). Pablo Campo was supported by a Ramon y Cajal Fellowship from the Spanish Ministry of Science and Innovation (RYC-2010–05748

    Dynamics of exoplanets and exosatellites in binaries

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    This dissertation is the result of the work made under the supervision of J.A. Docobo, Full Professor in Astronomy and Director of the Ramon María Aller Astronomical Observatory of the University of Santiago de Compostela. The core of the dissertation is a compendium of articles published in peer review publications indexed in the Journal Citation Reports, and in the Web of Science. The purpose of this work, suggested by prof. Docobo, is the study of the dynamics planetary systems, focusing on exoplanets and exosatellites in binary stars. The first part of the dissertation is a review of the state of the art in the fields of binary stars and exoplanet research. Then I present the work made in the determination of accurate binary star orbits. The knowledge of precise orbits of these systems is crucial for the determination of the dynamical evolution of the planets in them. The principal part of the dissertation comprises the study of the dynamics of exoplanet systems with exosatellites, and a study of the possible detection of exosatellites by means of the perturbations in the radial velocity signal of the planet

    Architecture, Innovative Human Education and Feeling: Inclusive Projects for People with Disabilities

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    It is feasible to combine teaching innovation and social inclusion, and transcend the academic sphere. At the CEU-San Pablo University, as part of the subject of «Architectural Composition», educational experiments were carried out based on collaboration between students of Architecture and volunteers with intellectual or visual disabilities. The objective was to devise criteria and spatial typologies to design places of human training. The methodology was interdisciplinary, through working sessions of mixed teams, with empathy characterizing the relationship between students and volunteers; the latter enriched the design sensitivity of the future architects by expressing their way of perceiving, interpreting and feeling educational spaces

    Development of a testing protocol for oil solidifier effectiveness evaluation

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    Chemical countermeasures for oil spill remediation have to be evaluated and approved by the U.S. Environmental Protection Agency before they may be used to remove or control oil discharges. Solidifiers are chemical agents that change oil from a liquid to a solid by immobilizing the oil and bonding the liquid into a solid carpet-like mass with minimal volume increase. Currently, they are listed as Miscellaneous Oil Spill Control Agent in the National Contingency Plan and there is no protocol for evaluating their effectiveness. An investigation was conducted to test the oil removal efficiency of solidifiers using three newly developed testing protocols. The protocols were qualitatively and quantitatively evaluated to determine if they can satisfactorily differentiate effective and mediocre products while still accounting for experimental error. The repeatability of the three protocols was 15.9, 5.1, and 2.7 %. The protocol with the best performance involved measuring the amount of free oil remaining in the water after the solidified product was removed using an ultraviolet–visible spectrophotometer and it was adopted to study the effect of solidifier-to-oil mass ratio, mixing energy, salinity, and beaker size (i.e., area affected by the spill) on solidifier efficiency. Analysis of Variances were performed on the data collected and results indicated that the beaker size increased spreading, which reduced removal efficiency. Mixing speed appears to impart a ceiling effect with no additional benefit provided by the highest level over the middle level. Salinity was found to be mostly an insignificant factor on performance

    Is Galea tixiensis Quintana, 2001 a synonym of G. leucoblephara Burmeister, 1861?

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    El género Galea (Rodentia, Caviidae) incluye cinco especies vivientes y dos extintas de cávidos terrestres y herbívoros, que ocupan pastizales y matorrales rocosos, tanto en áreas altas como bajas de América del Sur. Algunas muestras fósiles del Pleistoceno-Holoceno del centro-este de Argentina han sido referidas como Galea sp., G. musteloides o G. cf. musteloides y finalmente se describieron como una nueva especie bajo el nombre de G. tixiensis. Sin embargo, estudios recientes basados en series grandes de individuos fallaron en encontrar diferencias morfológicas cualitativas entre G. lecucoblephara y G. tixiensis. Sobre la base de estos hallazgos, en esta contribución revisamos el estatus taxonómico de la especie extinta G. tixiensis. Se examinaron 110 individuos de las tres subespecies actualmente reconocidas de G. leucoblephara (i.e., G. l. demissa, G. l. leucoblephara y G. l. littoralis) de Argentina, Bolivia y Paraguay. Se registraron nueve medidas cráneo-dentarias. Los datos cuantitativos se sometieron a un análisis de componentes principales (PCA) con el fin de identificar la contribución de cada medida a la varianza total. Los caracteres cualitativos se evaluaron a través de las comparaciones de los rasgos supuestamente diagnósticos de G. tixiensis con la variabilidad representada por las muestras recientes. Los espacios multivariados de las tres subespecies estudiadas se superpusieron ampliamente en el PCA, lo que sugiere que estos taxones no difieren significativamente en la figura del cráneo. El holotipo de G. tixiensis se ubicó dentro del morfoespacio correspondiente a muestras recientes de G. l. littoralis. Los caracteres cualitativos supuestamente diagnósticos de G. tixiensis también se verificaron en muestras recientes de G. leucoblephara, en particular de G. l. littoralis. Sobre la base de sus rasgos craneanos cualitativos y cuantitativos se sugiere que G. tixiensis es un sinónimo de G. leucoblephara. Los mayores valores para algunos rasgos craneanos cuantitativos en las muestras fósiles –comparadas con las actuales– son reinterpretados en este trabajo como una respuesta ecofenotipica a las condiciones climáticas más severas durante el Holoceno.The genus Galea (Rodentia, Caviidae) includes five living and two extinct species of terrestrial and herbivorous cavies that inhabit grasslandsand rocky scrub areas at both high and low elevations in South America. Fossil samples from the late Pleistocene-Holocene from central-easternArgentina have been referred to as Galea sp., G musteloides or G. cf. musteloides and finally described as a new species under the name of G. tixiensis. However, recent studies based on large series of individuals fail to find qualitative morphological differences between G. leucoblephara and G.tixiensis. Based on these findings, in this contribution we reviewed the taxonomic status of the fossil species G. tixiensis. A total of 110 individualsof the three currently recognized subspecies of G. leucoblephara (i. e., G. l. demissa, G. l. leucoblephara and G. l. littoralis) from Argentina Boliviaand Paraguay were examined. Nine craniodental measurements were recorded. Quantitative data were subjected to a principal component analysis (PCA) in order to identify the contribution of each measurement to the total variance. Qualitative characters were evaluated through the comparisons of the diagnostic traits of G. tixiensis with the variability derived from the recent samples. PCA showed a high overlap of the multivariate spaces of the three subspecies studied, suggesting that they do not differ significantly in terms of cranial shape. The holotype of G. tixiensis was allocated within the morphospace of the recent G. l. littoralis samples. Qualitative traits diagnostic of G. tixiensis were also recorded in recent samples of G. leucoblephara, in particular of G. l. littoralis. Based on both qualitative and quantitative cranial traits, we suggest that G. tixiensis is a synonym of G. leucoblephara. The morphological traits supposedly unique to G. tixiensis were also recorded in specimens of living populations of G. l. littoralis. The large values of some quantitative cranial traits in fossil samples -compared to living ones- are reinterpreted here as an ecophenotypical response to the more severe climatic conditions of the Holocene.Fil: Teta, Pablo Vicente. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales ; ArgentinaFil: Campo, Denise Heliana. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales ; Argentin

    A method for the characterisation of microplastics in sludge

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    Microplastics (MP) have become a concern owing to their increasing detection in the environment and potential impact on ecosystems. One of the main MP reservoirs is sludge generated during wastewater treatment. Estimates suggest that, through sludge settling, treatment processes remove between 80 and 90 % of MP present in wastewater. Nevertheless, reliable measurements of actual plastics loads retained by sludge are still lacking for management purposes. Hence, our goal was to validate a quick method for MP quantitation in sludge. Recovery tests were conducted with red low-density polyethylene (LDPE) fragments whose sizes ranged between 5 to 1 mm, 1 to 0.5 mm and 500 to 150 μm. For each size fraction, either 10 or 100 LDPE fragments were spiked into wet sludge (50 mL). Subsequent LDPE analysis involved steps such as freeze-drying, sieving, Fenton purification, visual shorting and FTIR identification. When expressed as number of fragments, quantitative (i.e. percentage values between 80 and 100) were obtained regardless of size fraction or initial spiked number. In terms of total spiked LDPE weight, however, recoveries consistently exceeded 100 % because LDPE fragments retained other materials. Such residues contributed to an overestimation of MP by weight up to 33 % of the 500−150 μm fraction

    Market risk premium used in 2010 by analysts and companies: A survey with 2.400 answers

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    The average MRP used by analysts in the United States and Canada (5.1%) was similar to the one used by their colleagues in Europe (5.0%), and United Kingdom (5.2%). But the average MRP used by companies in the United States and Canada (5.3%) was smaller than the one used by companies in Europe (5.7%), and United Kingdom (5.6%). The dispersion of the MRP used was high, but lower than that of the MRP used by professors: the average range of MRP used by analysts (companies) for the same country was 5.7% (4.1%) and the average standard deviation was 1.7% (1.2%). These statistics were 7.4% and 2.4% for the professors. Most previous surveys have been interested in the Expected MRP, but this survey asks about the Required MRP. The paper also contains the references that analysts and companies use to justify their MRP, and comments from 89 respondents that illustrate the various interpretations of what is the required MRP.market risk premium; required equity premium; expected equity premium; historical equity premium;

    Market risk premium used in 2010 by professors: A survey with 1,500 answers

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    The average Market Risk Premium (MRP) used in 2010 by professors in the United States (6.0%) was higher than the one used by their colleagues in Europe (5.3%). We also report statistics for 33 countries: the average MRP used in 2010 ranges from 3.6% (Denmark) to 10.9% (Mexico). 29% of the professors decreased the MRP in 2010, 16% increased it and 55% used the same MRP. The dispersion of the MRP used was high: the average range of MRP used by professors for the same country was 7.4% and the average standard deviation was 2.4%. Most previous surveys have been interested in the Expected MRP, but this survey asks about the Required MRP. The paper also contains the references that professors use to justify their MRP, and comments from 85 professors that illustrate the various interpretations of what is the required MRP.equity premium puzzle; required equity premium; expected equity premium; historical equity premium;

    Assessment of crude oil bioremediation potential of seawater and sediments from the shore of Lebanon in laboratory microcosms

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    With the planned oil and gas exploration activities off the coast of Lebanon, the risk of shoreline contamination with crude oil spills has become a major concern. This study aimed at assessing the crude oil bioremediation potential of the chronically polluted Lebanese shores in light of the continuous discharge of nutrient-rich sewage into the Mediterranean Sea and the long-lasting absence of proper sewage treatment systems. It was anticipated that, with the high pollution levels of the coastline, background concentrations of nutrients would be sufficient to sustain high intrinsic biodegradation rates without human intervention. Biodegradation experiments were conducted using crude oil-spiked beach sediments and seawater under natural attenuation and biostimulation conditions. The experiments were conducted at 18 and 28 °C to account for seasonal variation in temperature, background nutrient levels, and microbial communities. The biodegradability of oil constituents – namely alkanes and polycyclic aromatic hydrocarbons (PAHs), was monitored over a 42-day period using gas chromatography–mass spectrometry (GC–MS). Under biostimulation conditions, significant enhancement in the overall biodegradation rates of alkanes and PAHs was observed in seawater at 18 and 28 °C, while little to no improvement was measured at both temperatures in sediments where background nutrient levels were sufficient to induce near maximum intrinsic biodegradation rates. Under both natural attenuation and biostimulation treatments, the increase in temperature increased the oil biodegradation rates in sediment and seawater microcosms. In both instances, the overall trend in the biodegradation of individual alkanes and PAHs suggested a typical decrease in biodegradation rates with the increase in carbon number/rings and alkyl groups
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