196 research outputs found

    Modular evolution of the carnivoran pelvic girdle: a three-dimensional morphometric approach

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    Martín-Serra, A., Figueirido, B., Serrano, F., Palmqvist, P. MODULAR EVOLUTION OF THE CARNIVORAN PELVIC GIRDLE: A THREE-DIMENSIONAL MORPHOMETRIC APPROACH. 75th meeting of Vertebrate Palaeontology. Dallas (Texas). Journal of Vertebrate Palaeontology Supplement (Program and Abstracts) P. 176The pelvic girdle is a key skeletal structure within the appendicular skeleton in quadrupedal mammals. The pelvis anchors many important muscles and connects the hind limb to the axial skeleton. However, unlike other appendicular bones, each hemipelvis is composed of three different girdle bones: ilium, ischium and pubis. Here we investigate if the functional and developmental interactions among these bones accounts for the integration and modularity of the pelvis in mammalian carnivores. We use carnivorous mammals as a case study because our recent work has demonstrated that their appendicular skeleton is also integrated by functional reasons. A series of landmarks in 3D on one half of the pelvic girdle were digitized in a wide sample of living carnivorans. The landmarks were divided into four basic developmental units: illium, ischium, pubis and acetabulum. The latter was considered as a different unit because it interacts with the femoral head during development. Later, we tested different modularity hypotheses that consider all possible modules formed by the combination of these four developmental units. For each hypothesis, we calculated the RV coefficient, a proxy for morphological covariation. We compared each specific hypothesis with a distribution of RV coefficients resulting from randomly-defined modules to assess for statistical significance. One of the hypotheses with more statistical support separates the four original units as modules, which indicates a strong influence of development. Other supported hypotheses clearly point towards an association between the ischium and the pubis, with the illium and acetabulum more or less independent. However, these hypotheses cannot be unequivocally ascribed to functional interactions, because the ischium and the pubis also share some developmental processes. These results clearly indicate that the carnivoran pelvic girdle preserves a developmental modular structure with little modification attributable to functional adaptations, which agrees with previous studies that showed that the pelvis is conservative within each carnivoran family.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tec

    Step-by-step small-signal modeling and control of a light hybrid electric vehicle propulsion system

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    This paper develops step-by-step a complete electric model of a light hybrid electric vehicle propulsion system. This model includes the vehicle mass, the radius and mass of the wheels, the aerodynamic profile of the vehicle, the electric motor and the motor drive, among other elements. Each element of the model is represented by a set of equations, which lead to getting an equivalent electric circuit. Based on this model, the outer and inner loop compensators of the motor drive control circuit are designed to provide stability and a fast dynamic response to the system. To achieve this, the steady-state equations and the small-signal model of the equivalent electric circuit are also obtained. Furthermore, as these elements are the main load of the power distribution system of the fully electric and light hybrid electric vehicle, the input impedance model of the set composed of the input filter, the motor drive, the motor, and the vehicle is presented. This input impedance is especially useful to get the system stability of the entire power distribution system.This work has been partially supported by the Spanish Ministry of Economy and Competitiveness and FEDER (ERDF), through the research project "Storage and Energy Management for Hybrid Electric Vehicles based on Fuel Cell, Battery and Supercapacitors" -ELECTRICAR-AG- (DPI2014-53685-C2-1-R

    Selection and publication of network interface cards in multihomed pervasive computing devices

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    Proceedings of the 8th IEEE International Workshop on Middleware and system support for pervasive computing, march 21-25, 2011, Seattle, USAMany modern devices come with several, heterogeneous, network interface cards (NICs). However, simple operations like transferring data flows to the cheapest NIC or to one with enough Quality of Service (QoS) are awkward tasks on most Operating Systems. In this paper, we discuss the criteria to select the proper NIC for a given data flow. We also present a new Operating System service, called netqos, to publish data and figures of merit for these criteria. The main objective of netqos is providing relevant information to applications and middleware about NIC selection criteria, isolating them from the idiosyncrasies of the many QoS gathering tools and allowing to choose the proper NIC to fit their needs. We have built this new service as a synthetic file system for the Linux kernel. We describe our experiences in using it in a real-world scenario and the practical and inherent limitations of this approachProyecto CCG10-UC3M/TIC-4992 de la Comunidad Autónoma de Madrid y la Universidad Carlos III de Madri

    The development of selective stopping: qualitative and quantitative changes from childhood to early adulthood

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    Although progress has been made in elucidating the behavioral and neural development of global stopping across the lifespan, little is known about the development of selective stopping. This more complex form of inhibitory control is required in real-world situations where ongoing responses must be inhibited to certain stimuli but not others, and can be assessed in laboratory settings using a stimulus selective stopping task. Here we used this task to investigate the qualitative and quantitative developmental changes in selective stopping in a large-scale cross-sectional study with three different age groups (children, preadolescents, and young adults). We found that the ability to stop a response selectively to some stimuli (i.e., use a selective strategy) rather than non-selectively to all presented stimuli (i.e., use a global, non-selective strategy) is fully mature by early preadolescence, and remains stable afterwards at least until young adulthood. By contrast, the efficiency or speed of stopping (indexed by a shorter stop-signal reaction time or SSRT) continues to mature throughout adolescence until young adulthood, both for global and selective implementations of stopping. We also provide some preliminary findings regarding which other task variables beyond the strategy and SSRT predicted age group status. Premature responding (an index of “waiting impulsivity”) and post-ignore slowing (an index of cognitive control) were among the most relevant predictors in discriminating between developmental age groups. Although present results need to be confirmed and extended in longitudinal studies, they provide new insights into the development of a relevant form of inhibitory controlThis work was supported by grants PSI2017-84922-R (Ministerio de Economía y Competitividad (MINECO, Spain) and SI1/PJI/2019-00061 (Comunidad de Madrid, Spain; V PRICIT

    Analysis of location prediction performance of LZ algorithms using GSM Cell-based location data

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    Proceedings of the 5th International Symposium of Ubiquitous Computing and Ambient Intelligence (UCAMI 2011), December 5-8th, 2011, Riviera Maya, MexicoPredictions about users' next locations allow bringing forward their future context, thus having additional time to react. To make such predictions, algorithms capable of learning mobility patterns and estimating the next location are needed. This work is focused on making the predictions on mobile terminals, thus resource consumption being an important constraint. Among the predictors with low resource consumption, the family of LZ algorithms has been chosen to study their performance, analyzing the results drawn from processing location records of 95 users. The main contribution is to divide the algorithms into two phases, thus being possible to use the best combination to obtain better prediction accuracy or lower resource consumption.Proyecto CCG10-UC3M/TIC-4992 de la Comunidad Autónoma de Madrid y la Universidad Carlos III de Madri

    Influence of the Main Design Factors on the Optimal Fuel Cell-Based Powertrain Sizing

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    The design of the optimal power distribution system (PDS or powertrain) for fuel cell-based vehicles is a complex task due to PDS comprising one or more power converters, several types of secondary energy sources, a fuel cell, several control loops, and protections, among others. The optimized powertrain design tries to minimize the mass, volume, and cost, and also to improve system efficiency, fuel economy (both hydrogen and electricity), and vehicle autonomy. This paper analyzes the influence of four different factors that deeply affect the optimal powertrain design, in particular: the minimum power delivered by the fuel cell, the storage of the recovered energy from the regenerative braking periods, the battery technology, and the maximum battery state-of-charge variation. The analysis of these factors is carried out over a set of 9 different fuel cell-based architectures applied to a light vehicle, and a 10th architecture corresponding to a pure electric vehicle. This analysis provides the knowledge of how these design factors affect the mass, volume, and cost of the optimal power distribution architectures, and how they can be considered in the design.This research was funded by the Spanish Ministry of Economy and Competitiveness and ERDF, grant number DPI2014-53685-C2-1-R

    Analysis and Sizing of Power Distribution Architectures Applied to Fuel Cell Based Vehicles

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    The fuel cell based vehicles powertrain is an extensive system that comprises a fuel cell (FC) as the primary energy source, a set of power converters both unidirectional and bidirectional and batteries or supercapacitors as secondary energy sources. Its design is a complex task that affects the mass, volume, cost, efficiency and fuel economy of the vehicle. This paper describes a graphic and straightforward sizing of the secondary energy sources needed to fulfil the vehicle load requirements, as well as the set of equations related to the mass, cost and volume of each one of the power distribution subsystems. Moreover, this paper analysis ten different power distribution architectures to conclude which is the most suitable secondary energy source, the minimum sizing, cost, volume and weight, depending on the amount of power delivered by the fuel cell. Also, a 1.6 kW fuel cell based architecture is implemented and testing. The experimental results confirm the proposed methodology.This research was funded by the Spanish Ministry of Economy and Competitiveness and ERDF, grant number DPI2014-53685-C2-1-R. This work has been partially supported by the Spanish Ministry of Economy and Competitiveness and FEDER (ERDF), through the research project “Storage and Energy Management for Hybrid Electric Vehicles based on Fuel Cell, Battery and Supercapacitors”—ELECTRICAR-AG—(DPI2014-53685-C2-1-R)

    Physiological Regulation of Isocitrate Dehydrogenase and the Role of 2-Oxoglutarate in Prochlorococcus sp. Strain PCC 9511

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    The enzyme isocitrate dehydrogenase (ICDH; EC 1.1.1.42) catalyzes the oxidative decarboxylation of isocitrate, to produce 2- oxoglutarate. The incompleteness of the tricarboxylic acids cycle in marine cyanobacteria confers a special importance to isocitrate dehydrogenase in the C/N balance, since 2-oxoglutarate can only be metabolized through the glutamine synthetase/glutamate synthase pathway. The physiological regulation of isocitrate dehydrogenase was studied in cultures of Prochlorococcus sp. strain PCC 9511, by measuring enzyme activity and concentration using the NADPH production assay and Western blotting, respectively. The enzyme activity showed little changes under nitrogen or phosphorus starvation, or upon addition of the inhibitors DCMU, DBMIB and MSX. Azaserine, an inhibitor of glutamate synthase, induced clear increases in the isocitrate dehydrogenase activity and icd gene expression after 24 h, and also in the 2-oxoglutarate concentration. Iron starvation had the most significant effect, inducing a complete loss of isocitrate dehydrogenase activity, possibly mediated by a process of oxidative inactivation, while its concentration was unaffected. Our results suggest that isocitrate dehydrogenase responds to changes in the intracellular concentration of 2-oxoglutarate and to the redox status of the cells in Prochlorococcus

    Changes in Alcohol Use during the COVID-19 Pandemic among Young Adults: The Prospective Effect of Anxiety and Depression

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    Versión editorHealth measures instantiated to reduce the spread of COVID-19 have imposed significant constraints for the population and impacted on drinking habits and mental health. This study longitudinally compared changes in alcohol consumption before and after the COVID-19 outbreak and the impact of sociodemographic and mental health variables on such changes among a community sample of young adults. Data were collected in the context of a larger, ongoing longitudinal study. The sample consisted of 305 young adults from Spain aged between 18 and 26 years (mean age = 21.27, (SD = 2.21), female = 53.4%; college students = 61.6%) who completed first (November-2019 and February-2020; i.e., before the outbreak of COVID-19) and second follow-up questionnaires (March 2021, a year after the COVID-19 outbreak). Alcohol use (quantity and drinking frequency), depression and anxiety symptoms were measured. Quantity and frequency of alcohol use decreased from the preto post-COVID-19 period. A decrease in drinking frequency was observed among college students, but not in noncollege peers. Although we found no effect of pre-COVID-19 anxiety on alcohol use changes, those with more depressive symptoms at the pre-COVID assessment were more resistant to decreasing their drinking quantity and frequency after the COVID-19 outbreak. This information will be of value when designing interventions aimed at reducing harmful alcohol use and highlights the role of mental health status when identifying high risk populations of young-adults during this, and future, public health crisesFunding for this study was provided by the Consejería de Salud (Junta de Andalucía, Andalucía, Spain) under Grant Number PI-0503-2018 (Principal Investigator: Fermín Fernández Calderón). BV was supported by Fundación Carolina and SEGIB, and Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET

    Tailoring the thermoelectric properties of Skutterudites by nanocomposites

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    Póster presentado en la 34th Annual International Conference on Thermoelectrics (ICT) y en la 13th European Conference on Thermoelectrics(ECT), celebradas en Dresden del 28 de junio al 2 de julio de 2015.Skutterudites have attracted great attention for their promising potential on thermoelectric applications, such as harvesting the heat generated in industrial processes and automotive operations. To improve their thermoelectric figure of merit ,emphasis has gone into modifying the band structure through doping to enhance the Power Factor and reducing thermal conductivity through increasing phonon scattering by filling and in-situ nanocomposites formation.Depending on the nature of the nanoinclusions and the proportion in the matrix, it is possible to tailor the thermoelectric properties. In this work, different concentrations of oxides were included in a one-step synthesis mechanism, obtaining the Skutterudite phase with nanoinclusions and therefore, achieving lower thermal conductivities than those reported in literature.Peer Reviewe
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