Estudio de la electro-filtración a presión constante de suspensiones sólido-líquido

Debido a que los sistemas de filtración utilizados actualmentesólo pueden eliminar una parte del agua contenida en la suspensión, se han realizado investigaciones con elobjetivo de obtener mayores rendimientos en la filtraciónmediante la aplicación de un campo eléctrico en un filtro presión. Para ello, se han llevado a cabo electro-filtracionesaplicando una diferencia de presión constante de0.4 bar y diferentes valores de intensidad eléctrica (de 0 a2.21 A). Se ha estudiado la influencia del campo eléctricosobre el contenido en agua de la torta, la presión electroosmótica, a resistencia específica de la torta y el pH delfiltrado y del agua retenida en la torta. Se ha analizado elefecto de la electroforesis y de la electro-ósmosis sobreestas propiedades. El estudio de la variación del pH determinaque la operación unitaria de electro-filtración sóloes aplicable en los procesos donde el sólido obtenido seaun residuo o cuyas propiedades puedan ser modificadas.Por fin, se ha definido un nuevo parámetro que tiene encuenta la compresibilidad de la torta según la intensidadeléctrica aplicada y ha convenido en denominarse factorde electro-compresibilidad

Italia: bibliotecas de arte y bibliotecas de museos en Florencia: situación actual y perspectivas de futuro

Las visitas realizadas fueron las siguientes: bibliotecas de Museos (Biblioteca degli Uffizi), bibliotecas de instituciones especializadas de enseñanza (Kunsthistorisches Institut-Max Planck Institut, Biblioteca Berenson); de bibliotecas patrimoniales (Biblioteca Medicea-Laurenziana, Biblioteca Riccardiana) e incluso de una de las dos bibliotecas nacionales centrales italianas. Ésto permitió recabar información referente a aspectos logísticos, procesos técnicos especializados, aplicación de las TIC, análisis de los materiales patrimoniales en bibliotecas especializadas y estudio de las redes de bibliotecas especializadas en arte

The neurobiological foundations of learning disabilities

Learning disabilities constitute a heterogeneous group of disorders that involve significant alterations in different cognitive domains (acquisition and use of language, reasoning, mathematical skills, visuospatial abilities, and so forth) that are not accounted for by a low level of intelligence, inadequate sociocultural development or lack of academic opportunities. They result from an alteration in basic psychological processes, developmentally linked to an alteration in the central nervous system. Current functional neuroimaging techniques have made it possible to develop a new type of approach to the neurofunctional foundations underlying these disorders, especially with regard to difficulties in the realm of reading/writing (developmental dyslexia) and attention deficit hyperactivity disorder (ADHD), which have their highest incidence among the infantile population of school-age children. Development. Neuroimaging studies have revealed a pattern of atypical activity in both kinds of disorders. In the case of dyslexia, alterations have been observed in the perisylvian circuits that underlie the mechanisms involved in reading skills. Studies into ADHD suggest a fronto-striatal dysfunction linked to the difficulties encountered to achieve inhibitory control, as well as alterations in the inferior parietal and posterior temporal cortex. Conclusions. Functional neuroimaging studies have shown that the clinical manifestations of these disorders are not only due to a dysfunction in specific areas of the brain, but also to alterations in the pattern of connectivityLas dificultades de aprendizaje comprenden un grupo heterogéneo de trastornos que implican alteraciones significativas en diferentes dominios cognitivos (adquisición y uso del lenguaje, razonamiento, habilidades matemáticas, visuoespaciales, etc.) no justificadas por bajo nivel intelectual, desarrollo sociocultural inadecuado o falta de oportunidades académicas. Éstas son el resultado de una alteración en los procesos psicológicos básicos, evolutivamente ligados a una alteración del sistema nervioso central. Las actuales técnicas de neuroimagen funcional han permitido un nuevo tipo de acercamiento a las bases neurofuncionales de estos trastornos, particularmente de las dificultades en el ámbito de la lectoescritura (dislexia evolutiva) y del trastorno por déficit de atención e hiperactividad (TDAH), los cuales tienen el mayor nivel de incidencia en la población escolar infantil. Desarrollo. Los estudios de neuroimagen han revelado un patrón de actividad atípico en ambos tipos de trastorno. En el caso de la dislexia, se han observado alteraciones de los circuitos perisilvianos que sustentan los mecanismos de lectura. Los estudios sobre TDAH sugieren una disfunción frontoestriatal ligada a las dificultades para el control inhibitorio, así como alteraciones en la corteza temporal posterior y parietal inferior. Conclusiones. Los estudios de neuroimagen funcional revelan que las manifestaciones clínicas de estos trastornos no se deben sólo a la disfunción de áreas cerebrales concretas, sino también a alteraciones en el patrón de conectividadAs dificuldades de aprendizagem compreendem um grupo heterogéneo de perturbações que implicam alterações significativas em diferentes domínios cognitivos (aquisição e uso da linguagem, raciocínio, habilidades matemáticas, visuo-espaciais, etc.) não justificadas por baixo nível intelectual, desenvolvimento sócio-cultural inadequado ou falta de oportunidades académicas. Estas são o resultado de uma alteração nos processos psicológicos básicos, evolutivamente ligados a uma alteração do sistema nervoso central. As técnicas actuais de neuroimagem funcional permitiram um novo tipo de abordagem às bases neuro-funcionais destas perturbações, particularmente das dificuldades no âmbito da leitura e da escrita (dislexia evolutiva) e da perturbação por défice de atenção e hiperactividade (PDAH), as quais têm o maior nível de incidência na população escolar infantil. Desenvolvimento. Os estudos das neuroimagens revelaram um padrão de actividade atípico em ambos os tipos de perturbação. No caso da dislexia, foram observadas alterações dos circuitos perisilvícos que sustentam os mecanismos de leitura. Os estudos sobre o PDAH sugerem uma disfunção fronto-estriatal ligada às dificuldades no controlo inibitório, assim como alterações no córtex temporal posterior e parietal inferior. Conclusões. Os estudos de neuroimagem funcional revelam que as manifestações clínicas destas perturbações não se devem apenas à disfunção de áreas cerebrais concretas, como também a alterações no padrão de conectividad

Magnetoencephalographic assessment of changes in brain activity in normal aging when performing a task under interference conditions

Determinar si la realización de una tarea de reconocimiento con interferencia activa, producía cambios en los patrones de activación cerebral con respecto a la presentación de otra con interferencia pasiva. Población y metodología: en veinte ancianos sanos se midió con magnetoencefalografía. Se realizó a cada uno de ellos la escala de Memoria de Wechsler-III (WMS-III), la escala de Inteligencia de Wechsler, el Boston Naming Test, el test de fluidez verbal, el test de clasificación de tarjetas de Wisconsin, el trail Making Test y el test de colores y palabras (STROOP). Los registros se llevaron a cabo mediante un magnetoencefalógrafo de 148 canales capaz de medir la actividad magnética generada en toda la convexidad craneal. Resultados: encontramos una mayor activación en la condición de interferencia activa en las regiones mediales temporales, corteza visual, y región ventral anterior durante los primeros 400 milisegundos en el hemisferio izquierdo y únicamente en el derecho para la corteza visual, mientras que en la condición de interferencia pasiva, se obtuvo una mayor activación en la región ventral anterior durante los 700-800 milisegundos en el hemisferio izquierdo. Conclusión: la presentación de estos dos tipos de interferencia, activa y pasiva, modula los patrones de activación fronto-temporales en el envejecimiento normalTo determine whether performing a recognition task under interference conditions produces changes in brain activity pattern compared with the activity seen under conditions of passive interference. Population and methods: Twenty healthy elderly subjects were subjected to magnetoencephalography. In each patient we applied the Wechsler Memory Scale-III (WMS-III), the Wechsler Intelligence Scale, the Boston Naming Test, the verbal fluency test, the Wisconsin card classification test, the Trail Making Test and the colors and words test (STROOP). The recordings were made using a 148-channel magnetoencephalograph capable of measuring the magnetic activity generated within the entire cranial convexity. Results: Greater activation was recorded under active interference conditions in the medial temporal regions, visual cortex and anterior ventral area in the first 400 ms in the left hemisphere and only in the right hemisphere for the visual cortex, while under passive interference conditions, increased activation was obtained in the anterior ventral region during the 700-800 ms in the left hemisphere. Conclusion: The presentation of both types of interference, active and passive, modulates the fronto-temporal activation patterns in normal agin

Changes in brain activity in normal aging in an interference task tested by magnetoencephalography

La presentación de estímulos que interfieren en el mantenimiento de una información previa dificulta el reconocimiento posterior de ésta. La resistencia a la interferencia disminuye en el envejecimiento normal, aspecto que se traduce en una peor ejecución de tareas que comprometen a la memoria operativa y que podría estar relacionado con una disfunción ejecutiva. Nuestro objetivo consistió en comprobar si la realización de una tarea de reconocimiento con interferencia activa, producía cambios en los patrones de activación cerebral con respecto a la presentación de otra con interferencia pasiva, en una muestra de veinte ancianos sanos y medido con magnetoencefalografía. Los resultados mostraron la presencia de una mayor activación en la condición de interferencia activa en las regiones mediales temporales, corteza visual, y región ventral anterior durante los primeros 400 milisegundos en el hemisferio izquierdo y únicamente en el derecho para la corteza visual, mientras que en la condición de interferencia pasiva, se obtuvo una mayor activación en la región ventral anterior durante los 700-800 milisegundos en el hemisferio izquierdo. Todo ello sugiere que la presentación de estos dos tipos de interferencia, activa y pasiva, modula los patrones de activación fronto-temporales en el envejecimiento normalThe presentation of stimuli interfering with the maintenance of previous information makes difficult the subsequent recognition of it. The interference resistance decreases in normal aging, which is evidenced as a worse performance in tasks affecting working memory and that could be related to an executive dysfunction. Our aim was to establish if performing a recognition task under active interference conditions caused changes in brain activation patterns from the performance of another task under passive interference conditions in a sample of 20 healthy elderly patients, measured with magnetoencephalography. The results evidenced the presence of a greater activation under active interference conditions in the medial temporal regions, visual cortex and anterior ventral area in the first 400 milliseconds in the left hemisphere and only in the right hemisphere for the visual cortex, while under passive interference conditions, a greater activation was obtained in the anterior ventral region during the 700-800 milliseconds in the left hemisphere. All of this suggests that the presentation of both types of interference, active and passive, modulates the fronto-temporal activation patterns in normal agin

Searches for neutrinoless double beta decay

Neutrinoless double beta decay is a lepton number violating process whose observation would also establish that neutrinos are their own anti-particles. There are many experimental efforts with a variety of techniques. Some (EXO, Kamland-Zen, GERDA phase I and CANDLES) started take data in 2011 and EXO has reported the first measurement of the half life for the double beta decay with two neutrinos of $^{136}$Xe. The sensitivities of the different proposals are reviewed.Comment: 8 pages, prepared for TAUP 201

Searches for neutrinoless double beta decay

Neutrinoless double beta decay is a lepton number violating process whose observation would also establish that neutrinos are their own anti-particles. There are many experimental efforts with a variety of techniques. Some (EXO, Kamland-Zen, GERDA phase I and CANDLES) started take data in 2011 and EXO has reported the first measurement of the half life for the double beta decay with two neutrinos of $^{136}$Xe. The sensitivities of the different proposals are reviewed.Comment: 8 pages, prepared for TAUP 201

Searches for neutrinoless double beta decay

Neutrinoless double beta decay is a lepton number violating process whose observation would also establish that neutrinos are their own anti-particles. There are many experimental efforts with a variety of techniques. Some (EXO, Kamland-Zen, GERDA phase I and CANDLES) started take data in 2011 and EXO has reported the first measurement of the half life for the double beta decay with two neutrinos of $^{136}$Xe. The sensitivities of the different proposals are reviewed.Comment: 8 pages, prepared for TAUP 201

Growth-promoting effects of sustained swimming in fingerlings of glithead sea bream (Sparus aurata L.)

Fish growth is strongly influenced by environmental and nutritional factors and changing culture conditions can help optimize it. The importance of early-life experience on the muscle phenotype later in life is well known. Here, we study the effects of 5 weeks of moderate and sustained swimming activity (5 BL s−1) in gilthead sea bream during early development. We analysed growth and body indexes, plasma IGF-I and GH levels, feed conversion, composition [proximate and isotopic (15N/13C)] and metabolic key enzymes (COX, CS, LDH, HOAD, HK, ALAT, ASAT) of white muscle. Moderate and continuous exercise in fingerlings of gilthead sea bream increased plasma IGF-I, whereas it reduced plasma GH. Under these conditions, growth rate improved without any modification to feed intake through an increase in muscle mass and a reduction in mesenteric fat deposits. There were no changes in the content and turnover of muscle proteins and lipid reserves. Glycogen stores were maintained, but glycogen turnover was higher in white muscle of exercised fish. A lower LDH/CS ratio demonstrated an improvement in the aerobic capacity of white muscle, while a reduction in the COX/CS ratio possibly indicated a functional adaptation of mitochondria to adjust to the tissue-specific energy demand and metabolic fuel availability in exercised fish. We discuss the synergistic effects of dietary nutrients and sustained exercise on the different mitochondrial responses

Eclipsing binaries in open clusters. III. V621 Per in chi Persei

V621 Persei is a detached eclipsing binary in the open cluster chi Persei which is composed of an early B-type giant star and a main sequence secondary component. From high-resolution spectroscopic observations and radial velocities from the literature, we determine the orbital period to be 25.5 days and the primary velocity semiamplitude to be K = 64.5 +/- 0.4 km/s. No trace of the secondary star has been found in the spectrum. We solve the discovery light curves of this totally-eclipsing binary and find that the surface gravity of the secondary star is log(g_B) = 4.244 +/- 0.054 (cm/s). We compare the absolute masses and radii of the two stars in the mass--radius diagram, for different possible values of the primary surface gravity, to the predictions of stellar models. We find that log(g_A) is approximately 3.55, in agreement with values found from fitting Balmer lines with synthetic profiles. The expected masses of the two stars are 12 Msun and 6 Msun, and the expected radii are 10 Rsun and 3 Rsun. The primary component is near the blue loop stage in its evolution.Comment: Accepted for publication in MNRAS (10 pages, 5 figures