161 research outputs found

    Morphological Variations of Wild Populations of Brycon dentex (Characidae, Teleostei) in the Guayas Hydrographic Basin (Ecuador). The Impact of Fishing Policies and Environmental Conditions

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    The Guayas, located in Ecuador, is the largest basin in the Pacific Ocean and has an inventory of 123 native freshwater species. Most of these are endemic species that are threatened or at-risk due to anthropogenic activity and the modification, fragmentation, and destruction of habitats. The aim of this study was to determine the morphometric variation in three wild populations of Brycon dentex in the Guayas basin rivers and their connections to fishing management and environmental conditions. A total of 200 mature fish were captured, and 26 morphometric parameters were measured. The fishing policies (Hypothesis 1) and environmental conditions (Hypothesis 2) were considered fixed factors and were validated by t-tests. The morphological variation among the three populations (Hypothesis 3) was validated through a discriminant analysis. Fishing policies and resource management were found to generate morphological differences associated with body development. In addition, the environmental conditions were found to influence the size and structure of Brycon dentex populations. The analyzed populations were discriminated by the generated morphometric models, which differentiated Cluster 1 (Quevedo and Mocache rivers) with high fishing pressure from Cluster 2 (Pintado river) with medium–low fishing pressure. Morphometric differentiation by discriminant analysis is a direct and economic methodology that can be applied as an indicator of diversity maintenance

    Usefulness of Discriminant Analysis in the Morphometric Differentiation of Six Native Freshwater Species from Ecuador

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    The aim of this research was to find out the morphometric differentiation of six native freshwater species in the Guayas Hydrographic Basin (Ecuador) by means of discriminant analysis. A total of 1355 mature fishes (Cichlasoma festae, Andinoacara rivulatus, Dormitator latifrons, Bryncon dentex, Hoplias microlepis and Leporinus ecuadorensis) were captured and 27 morphometric measurements and 20 landmarks were used. Two-way analysis of variance with species and sex as fixed factors and discriminant analysis were applied. The selection of the most discriminant variables was made applying the F of Snedecor, Wilks’-Lambda and the 1-Tolerance. While sex within species had no significant effect on the morphology, differences among species were significant. Twenty-seven morphological variables showed highly significant differences among six native freshwater species. Nine biometric variables with high discriminant power were selected. The six species analyzed were discriminated by the morphometric models generated, thus showing that discriminant analysis was useful for differentiating species. The morphometric differentiation by discriminant analysis is a direct, simple and economic methodology to be applied in situ in rural communities. It favors the implementation of a livestock development program and it could be used with other native freshwater species in the Guayas Hydrographic Basin

    KLaF4 nanocrystallisation in oxyfluoride glass-ceramics

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    Nanocrystallisation of the cubic and hexagonal polymorphs of KLaF 4 in a 70SiO2-7Al2O3-16K 2O-7LaF3 (mol%) glass has been achieved by heat treatment above the glass transition temperature. For treatment at 580°C, only the cubic structure crystallises, with a maximum crystallite size of ~9 nm. At higher temperatures, crystallisation of the hexagonal structure also takes place. The crystallisation process has been analysed using several thermal and structural techniques and is revealed to occur from a constant number of nuclei. The formation of a viscous barrier which inhibits further crystal growth and limits the crystal size to the nanometric range is observed. The title materials doped with lanthanide ions may be good candidates for optical applications

    Phosphate/Silicate Ratio Allows for Fine-Tuning of Bioactive Glass Crystallisation and Glass-Ceramic Microstructure

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    A combination of XRD, solid-state NMR and state-of-the-art imaging techniques were used to investigate how the calcium orthophosphate/calcium silicate ratio affects the crystallisation of bioactive glasses in the system SiO2-P2O5-CaO-CaF2. In the phosphate-free glass, xonotlite, wollastonite and cuspidine crystallised. From 2.4 mol% P2O5, fluorapatite also formed, while the amount of wollastonite decreased. Crystallisation tendency was low for low phosphate contents, while above 3 mol% P2O5 it increased. The phosphate-free glass showed a volume crystallisation mechanism with constant activation energy. By contrast, the glass with the largest phosphate to silicate ratio showed both volume and surface crystallisation, causing a pronounced decrease in activation energy with crystallisation degree. This work shows that by changing the phosphate/silicate ratio we can determine which crystal phases form, obtaining for example fluorapatite-free or wollastonite-free glass-ceramics, depending on the desired application and properties such as mechanical strength or activity in contact with physiological solutions

    ICT education policies in Spain after School Program 2.0: Emerging Trends

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    En este artículo se analiza la situación actual de las políticas educativas destinadas a laincorporación de las TIC a las escuelas en una muestra de ocho comunidades autónomasde España (Andalucía, Canarias, Cataluña, Extremadura, Madrid, País Valenciano, PaísVasco y Principado de Asturias) después del proceso impulsado por el Programa Escuela2.0. Este programa estuvo vigente durante el periodo 2009­2012 y respondió al modelo 1:1,de un ordenador por estudiante. Este análisis se guió por las siguientes cuestiones: ¿Quéefectos permanecen de las experiencias de políticas educativas del modelo 1:1?; ¿Quénuevos proyectos o programas están vigentes en los sistemas educativos de lascomunidades autónomas? ¿Qué nuevas tendencias con relación a las TIC estánemergiendo en la agenda educativa de las políticas autonómicas? Se concluye que lasnuevas políticas TIC, entre otras acciones, apuntan a centrar su atención en laincorporación de las PDI a todas las aulas, a la dotación de tabletas a los estudiantes envez de miniportátiles, a políticas de sustitución de los libros de texto de papel porplataformas de contenidos digitales y a la creación de portales de recursos en la nube. Seconstata también la ausencia de un programa o política educativa TIC coordinada a nivelde todo el estado como fue la experiencia del Programa Escuela 2.0.In this article the current situation of educational policies for the incorporation of ICT inschools in a sample of eight regions of Spain (Andalusia, Canary Islands, Catalonia,Extremadura, Madrid, Valencia, the Basque Country and the Principality of analyzesAsturias) after the process driven by the Escuela 2.0 program. This program was in effectduring the period 2009­2012 and responded to the 1:1 model of a computer per student.This analysis was guided by the following questions: What effects remain from theexperiences of educational policies of the 1:1 model?; What new projects or programs arein place in the educational systems of the regions? What new trends in relation to ICT areemerging in the educational agenda of regional policies? We conclude that the new ICTpolicy, among other things, aim to focus on the integration of IDPs to all classrooms toequipping students tablets instead of netbooks, a substitution policies textbooks paper fordigital content platforms, to create portals of cloud resources. The absence of aneducational program or policy level ICT coordinated statewide as was the experience ofSchool Program 2.0 has been observed

    The Absence of Caspase-8 in the Dopaminergic System Leads to Mild Autism-like Behavior

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    In the last decade, new non-apoptotic roles have been ascribed to apoptotic caspases. This family of proteins plays an important role in the sculpting of the brain in the early stages of development by eliminating excessive and nonfunctional synapses and extra cells. Consequently, impairments in this process can underlie many neurological and mental illnesses. This view is particularly relevant to dopamine because it plays a pleiotropic role in motor control, motivation, and reward processing. In this study, we analyze the effects of the elimination of caspase-8 (CASP8) on the development of catecholaminergic neurons using neurochemical, ultrastructural, and behavioral tests. To do this, we selectively delete the CASP8 gene in cells that express tyrosine hydroxylase with the help of recombination through the Cre-loxP system. Our results show that the number of dopaminergic neurons increases in the substantia nigra. In the striatum, the basal extracellular level of dopamine and potassium-evoked dopamine release decreased significantly in mice lacking CASP8, clearly showing the low dopamine functioning in tissues innervated by this neurotransmitter. This view is supported by electron microscopy analysis of striatal synapses. Interestingly, behavioral analysis demonstrates that mice lacking CASP8 show changes reminiscent of autism spectrum disorders (ASD). Our research reactivates the possible role of dopamine transmission in the pathogenesis of ASD and provides a mild model of autism.Ministerio de Economía y Competitividad RTI2018-098645-B-I00, PID2019-109569GB-I00, RTI2018-099778-B-I00Junta de Andalucía P18-RT-1372, US-1264806, PI-0080-2017, PI-0009-2017, PI-0134-2018, PEMP-0008-2020, P20_00958, CTS-510Instituto de Salud Carlos III PI18/01691Instituto de Investigación e Innovación en Ciencias Biomédicas de Cádiz-INiBICA LI19/06IN-CO22, IN-C09European Union 95568

    Social and environmental aspects of the energy transition

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    The need to promote a swift, efficient and fair energy transition to clean, secure and efficient energy production, storage, transport, and consumption is a major challenge for the future of the planet ( EC 2020 ). Currently, massive emissions of greenhouse gases ( particularly CO2 ) and other pollutants are changing global climate, and the lasts report of the Intergovernmental Panel on Climate Change ( IPCC 2018 ) advised that keeping the temperature increase below 1.5 ºC will require drastic, urgent and internationally coordinated actions. These initiatives will greatly affect advanced economies, characterized by high energy consumption, which should seek for clean and secure local energy sources, but they are also highly relevant for quickly developing countries, whose biodiversity, natural resources and standards of living are at risks due to over exploitation of local resources or to accumulation of waste products of energy production technologies coming from elsewhere. These processes of transition, though, have generated a variety of social and environmental impacts and, at the same time, have triggered complex questions about sustainability and social acceptance ( i.e. Sánchez-Zapata et al. 2019 for wind and solar energy production in Spain ). Social and environmental aspects of the transition to clean, secure and efficient energy production, storage, transport, and consumption should then be fully incorporated into research on new energy sources to ensure its sustainability.Peer reviewe

    Association between maltreatment and polydrug use among adolescents.

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    Different studies have related sexual and physical abuse during childhood and adolescence to the development of substance abuse disorders. Nevertheless, we are not aware of the role that other more common maltreatment types, such as neglect, will play among the most risky pattern of consumption: the polydrug use. A clinical sample of 655 adolescents, divided into two groups: polydrug users and non-polydrug users, were assessed on their pattern of drug consumption, history of childhood maltreatment, current psychopathology and their family history of alcoholism. Polydrug users had a greater prevalence of all types of maltreatment, although the most associated to this group were sexual abuse and emotional neglect. Other relevant variables to adolescent consumption were: the diagnosis of depressive disorder, the presence of anxiety traits and the family history of alcohol dependence. Polydrug users have higher risks of having had problems during infancy and adolescence, such as maltreatment and other psychopathological conditions, with the addition of family history of alcoholism. Accordingly, practitioners should take into account that those variables may influence polydrug abuse because it is the most risky pattern for subsequent dependence of substances, and they should always be considered during treatment.This research was funded by the “Plan Nacional Sobre Drogas” from the Ministry of Health, Social Services and Equality (Spain).Peer reviewe

    Overview of recent TJ-II stellarator results

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    The main results obtained in the TJ-II stellarator in the last two years are reported. The most important topics investigated have been modelling and validation of impurity transport, validation of gyrokinetic simulations, turbulence characterisation, effect of magnetic configuration on transport, fuelling with pellet injection, fast particles and liquid metal plasma facing components. As regards impurity transport research, a number of working lines exploring several recently discovered effects have been developed: the effect of tangential drifts on stellarator neoclassical transport, the impurity flux driven by electric fields tangent to magnetic surfaces and attempts of experimental validation with Doppler reflectometry of the variation of the radial electric field on the flux surface. Concerning gyrokinetic simulations, two validation activities have been performed, the comparison with measurements of zonal flow relaxation in pellet-induced fast transients and the comparison with experimental poloidal variation of fluctuations amplitude. The impact of radial electric fields on turbulence spreading in the edge and scrape-off layer has been also experimentally characterized using a 2D Langmuir probe array. Another remarkable piece of work has been the investigation of the radial propagation of small temperature perturbations using transfer entropy. Research on the physics and modelling of plasma core fuelling with pellet and tracer-encapsulated solid-pellet injection has produced also relevant results. Neutral beam injection driven Alfvénic activity and its possible control by electron cyclotron current drive has been examined as well in TJ-II. Finally, recent results on alternative plasma facing components based on liquid metals are also presented. ISSN:0029-5515 ISSN:1741-432
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