952 research outputs found

    A longitudinal retrospective study on intracranial arterial pulsatility index: its evolution in ten years' time and how it relates to the occurrence of cerebral and systemic ischemic disease

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    BACKGROUND AND AIMS: Intracranial arterial pulsatility index (PI) has been related to old age, hypertension, diabetes and small vessel disease. However, the cross- sectional design of most studies prevents a proper assessment of causality and evolution. We sought to explore how this index changes through time, which conditions affect this evolution and whether or not it can predict the occurrence of future ischemic events. METHODS: Between the years 2001-2006, 1288 patients underwent a transcranial Doppler evaluation in the Department of Neurology of the Hospital Universitario Central de Asturias. PI values for the middle cerebral and basilar arteries were systematically annotated. After exclusion of deceased patients and significant large artery stenoses, 89 patients were recruited for a re-evaluation in 2012. Afterwards, the sample was expanded up to 150 patients, with 61 randomly selected patients –either alive or deceased- who did not undergo a second exploration. Both groups had their clinical files reviewed, with special attention to vascular risk factors and brain or coronary ischemic events. RESULTS AND DISCUSSION: Our results pointed to the following conclusions: • Intracranial arterial PI works as a dynamic measure of both cerebral and systemic vascular disease. • Age is the main factor influencing PI value and variation, but, within a certain age group, PI is able to point subjects at higher long-term risk of future ischemic events. • Basilar artery PI seems to be a better predictor of future cerebral and coronary ischemic disease than middle cerebral artery PI

    Estudio de la cinética de adsorción de Cu y Hg a partir de soluciones binarias usando quitosano

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    pEn este trabajo se estudió la cinética de adsorción de Cu(II) y Hg(II) en quitosano a partir de una solución binaria, a diferentes concentraciones iniciales de los iones metálicos, tamaño de partículas del adsorbente y velocidad de agitación. El quitosano fue extraído por métodos químicos de caparazón de camarón. Soluciones de 1 L de Cu(II) y Hg(II) fueron puestas en contacto con 2 g de quitosano y se agitaron por un período de 8 h. Al final del proceso, las muestras fueron analizadas en un espectrómetro de absorción atómica. Los datos experimentales fueron evaluados aplicando los modelos cinéticos de pseudo-primer orden y pseudo-segundo orden. Los resultados del proceso de adsorción de los iones metálicos Cu(II) y Hg(II) con quitosano, mostraron que en la mayoría de los casos, ambos iones fueron eficazmente adsorbidos por la quitosano, obteniéndose un porcentaje de adsorción entre 44-100 % para Cu(II) y entre 95-100 % para el Hg(II). Para ambos iones, los resultados mostraron que a bajas concentraciones el proceso de adsorción se ajusta mejor al modelo de pseudo-primer orden y a concentraciones altas el modelo que mejor se ajusta a los datos experimentales es el modelo de pseudo-segundo orden; es decir, el paso limitante en la velocidad es la reacción de adsorción y no la transferencia de masa./pp /pp /ppstrongPalabras claves:/strong Caparazón de camarón; Cinética de adsorción; Modelos cinéticos; Solución binaria; Quitosano/p pDOI: a href="http://dx.doi.org/10.5377/nexo.v24i1.591"http://dx.doi.org/10.5377/nexo.v24i1.591/a/p pNexo, Vol. 24, No. 1, pp. 20-32, 2011/

    Thermographic imaging: assessment of drought and heat tolerance in Spanish germplasm of Brachypodium distachyon.

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    The annual grass Brachypodium distachyon has been recently recognized as the model plant for functional genomics of temperate grasses, including cereals of economic relevance like wheat and barley. Sixty-two lines of B. distachyon were assessed for response to drought stress and heat tolerance. All these lines, except the reference genotype BD21, derive from specimens collected in 32 distinct locations of the Iberian Peninsula, covering a wide range of geo- climatic conditions. Sixteen lines of Brachypodium hybridum, an allotetraploid closely related to B. distachyon were used as reference of abiotic-stress well-adapted genotypes. Drought tolerance was assessed in a green-house trial. At the rosette-stage, no irrigation was applied to treated plants whereas their replicates at the control were maintained well watered during all the experiment. Thermographic images of treated and control plants were taken after 2 and 3 weeks of drought treatment, when stressed plants showed medium and extreme wilting symptoms. The mean leaf temperature of stressed (LTs) and control (LTc) plants was estimated based upon thermographic records from selected pixels (183 per image) that strictly correspond to leaf tissue. The response to drought was based on the analysis of two parameters: LTs and the thermal difference (TD) between stressed and control plants (LTs – LTc). The response to heat stress was based on LTc. Comparison of the mean values of these parameters showed that: 1) Genotypes better adapted to drought (B. hybridum lines) presented a higher LTs and TD than B. distachyon lines. 2) Under high temperature conditions, watered plants of B. hybridum lines maintained lower LTc than those of B. distachyon. Those results suggest that in these species adaptation to drought is linked to a more efficient stomata regulation: under water stress stomata are closed, increasing foliar temperature but also water use efficiency by reducing transpiration. With high temperature and water availability the results are less definite, but still seems that opening stomata allow plants to increase transpiration and therefore to diminish foliar temperature

    Mechanical properties and coefficient of thermal expansion of β-eucryptite sintered by microwave technique

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    [ES]: La técnica de sinterización no convencional de microondas permite obtener materiales de ß-eucriptita en estado sólido cristalino con densidades cercanas a la teórica (~99 %). Se ha observado una diferencia considerable en estos materiales respecto a la técnica convencional en términos de densificación, microestructura, coeficiente de expansión térmica y propiedades mecánicas. Los valores de dureza y módulo de Young obtenidos mediante sinterización por microondas a 1200 ºC-5 min han sido relativamente altos, 6.8 GPa y 101 GPa, respectivamente, en comparación con el material obtenido mediante horno convencional (3.9 GPa y 58 GPa, respectivamente). Los datos dilatométricos obtenidos, incluyendo el intervalo de temperatura criogénica (-150 ºC a +150 ºC), muestran un coeficiente de expansión térmica controlado y negativo en todo el rango de temperaturas. La combinación de un calentamiento rápido junto con la reducción drástica en el tiempo de ciclo y el ahorro energético, hace que la técnica de microondas sean una clara alternativa a otro tipo de calentamientos.[EN]: Microwave non-conventional sintering technique allows obtaining fully dense glass-free β-eucryptite bulk material (∼99 %). A considerable difference in the densification, microstructure, coefficient of thermal expansion behaviour and mechanical properties, between conventional and non-conventional sintered specimens was observed. The hardness and Young’s modulus values obtained by microwaves at 1200 °C-5min have been relatively high, 6.8 GPa and 101 GPa, respectively, compared to conventional sintering (3.9 GPa and 58 GPa, respectively). Very low thermal expansion materials have been obtained in a wide temperature range including cryogenic temperatures (from -150 ºC to 150 ºC). The high heating rate along with the lower energy consumption makes microwave technique a clear alternative to other types of sintering methods.Los autores desean agradecer el apoyo financiero recibido de la UPV dentro de los proyectos SP20120621 y SP20120677 y, al gobierno español a través del proyecto (TEC2012-37532-C02-01). A. Borrell, agradece al Ministerio de Ciencia e Innovación su contrato de Juan la Cierva (JCI-2011-10498).Peer Reviewe

    Experimental results and modelling of humidity control strategies for greenhouses in continental and coastal settings in the Mediterranean region. II: Modelling of strategies

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    Strategies for humidity control —with and without heating— were evaluated via simulations performed with apreviously developed model (see accompanying paper, this issue, part I). With heating, the best strategy combined theuse of a humidity setpoint with step control of the roof window, increasing the ventilation in line with the outsidetemperature. Without heating, the best strategy again combined the use of a humidity setpoint with step control of theroof window, but required ventilation to be increased in line with the inside air temperatur

    Gulf of Cadiz beaches: A comparative response to storm events

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    The aim of the present paper is to compare the profile response of two mesotidal beaches (Faro, 10 km long, Algarve; La Barrosa, 8 km long, Cadiz) within a single regional physiographic unit (the Gulf of Cadiz) to the same storm event (January, 1996). For this comparison, a series of beach surveys was used, including a total of 10 study sites, five at each study area. The two beaches belong to exposed, mesotidal, sandy shores, and have a similar coastal orientation. However, the response time-scale is different for each one. Faro showed a total amount of 130 000 m³ of erosion due to the storm, with a complete post-storm recovery after one tidal cycle. La Barrosa had a total sand loss of 80 000 m³ due to the storm, with a final recovery of 60 000 m³, 4-6 months after the event. These differences are due to the beaches' different morphodynamic behaviours. Whereas Faro is a reflective beach, with dominant plunging breakers, La Barrosa is mainly dissipative, having spilling breakers. The difference in beach slope and grain size could also be important in determining their response to storm events.El objetivo del presente trabajo es comparar la respuesta, ante un mismo episodio de tormenta (enero de 1996), de dos playas mesomareales de comportamiento distinto (Praia de Faro, de 10 km de longitud en el Algarve, y La Barrosa, de 8 km de longitud en Cádiz) pero pertenecientes a la misma unidad fisiográfica (el golfo de Cádiz). Para esta comparación se han estudiado una serie de levantamientos topográficos que incluyen un total de diez líneas de perfilamiento, cinco en cada área de estudio. Ambas playas se localizan en costas arenosas, expuestas, mesomareales y con una orientación similar. Sin embargo, el tiempo de respuesta es diferente en cada caso. Praia de Faro mostró una erosión total de 130 000 m³ debida a temporales y una recuperación completa tras un único ciclo mareal. La Barrosa presentó una pérdida total de arena de 80 000 m³ asociada a los temporales, con una recuperación final de 60 000 m³ después de 4 a 6 meses de los temporales. Estas diferencias son debidas al desigual comportamiento morfodinámico mostrado por ambas playas. Así, mientras Praia de Faro es una playa reflectiva con rotura dominante de tipo plunging, La Barrosa es predominantemente disipativa y con una rotura de tipo spilling. Del mismo modo, las diferencias en la pendiente y el tamaño de grano pueden ser también importantes a la hora de explicar la respuesta de ambas playas ante la llegada de temporales.Instituto Español de Oceanografí

    Occupational exposure to ionizing radiation and risk of lymphoma subtypes: Results of the Epilymph European case-control study

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    Background: Evidence linking risk of lymphoma and B-cell lymphoma subtypes to ionizing radiation is inconclusive, particularly at low exposure levels. Methods: We investigated risk of lymphoma (all subtypes), B-cell lymphomas, and its major subtypes, associated with low-level occupational exposure to ionizing radiation, in 2346 lymphoma cases and 2463 controls, who participated in the multicenter EpiLymph case-control study. We developed a job-exposure matrix to estimate exposure to ionizing radiation, distinguishing between internal and external radiation, and we applied it to the lifetime occupational history of study subjects, We calculated the Odds Ratio (OR) and its 95% confidence interval (95% CI) for lymphoma (all subtypes combined), B-cell lymphoma, and its major subtypes using unconditional, polytomous logistic regression adjusting for age, gender, and education. Results: We did not observe an association between exposure metrics of external and internal radiation and risk of lymphoma (all subtypes), nor with B-cell lymphoma, or its major subtypes, at the levels regularly experienced in occupational settings. An elevated risk of diffuse large B cell lymphoma was observed among the most likely exposed study subjects with relatively higher exposure intensity, which would be worth further investigation. Conclusions: Further investigation is warranted on risk of B cell lymphoma subtypes associated with low-level occupational exposure to external ionizing radiation, and to clarify whether lymphoma should be included among the cancer outcomes related to ionizing radiation

    PD-1 is a marker of activation on tumor infiltrating NK cells in head and neck cancer

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    Co-inhibitory immune checkpoint receptors have become important targets for cancer immunotherapy. Programmed death 1 (PD-1) has been well-characterized on T cells in many cancer types, including head and neck cancer (HNC), for its ability to mediate activation and eventually T cell exhaustion in the tumor microenvironment. However, PD-1 expression on NK cells, which are crucial innate immune effector cells against cancer, remains largely undefined. In the setting of HNC, NK cells mediate lysis of EGFR-overexpressing tumor targets via cetuximab-mediated antibody dependent cytotoxicity (ADCC). Indeed, cetuximab has shown to be clinically effective but only to a modest extent. Therefore, it is necessary to investigate how cetuximab modulates activation of immune effector cell infiltrates in the tumor microenvironment in order to improve or extend its therapeutic efficacy. We hypothesized that expression of PD-1 per se on NK cells may constitute a marker of a chronically activated phenotype, which is suppressed only after ligation by its cognate ligand programmed death ligand-1 (PD-L1). Thus, tumor cell-expressing PD-L1 may present as a crucial mediator of immunosuppression in the tumor microenvironment decreasing cytotoxicity of cetuximab activated PD-1 expressing NK cells. Herein, using The Cancer Genome Atlas (TCGA) data for 500 HNC patients' tumors, we found that PD-1 expression correlates with NK activation markers. Indeed, HNC patients also exhibit higher levels of circulating and tumor infiltrating PD-1+ NK cells, and neoadjuvant cetuximab treatment increased this frequency in vitro and in vivo in a prospective Phase II trial. In addition, anti-PD-1 mAb nivolumab enhanced cetuximab mediated NK cell activation and HNC cell lysis. Therefore, blocking PD-L1/PD-1 axis may be a useful approach to reverse immune evasion of HNC tumors to cetuximab therapy by reversing NK cell dysfunction

    (I)Migrantes, diversidades e desigualdades no sistema educativo português : balanço e perspectivas

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    O objectivo do presente artigo consiste em procurar transmitir um olhar sociologicamente informado no que concerne à situação portuguesa no domínio das políticas educativas públicas e investigações produzidas relacionadas com o sistema educativo e a (i)migração, ou seja, com a tentativa de construção de uma educação intercultural. Neste sentido, será realizada uma análise descritiva e compreensivo-interpretativa da evolução desta problemática em Portugal desde que a mesma se tornou objecto de reflexão por parte de investigadores/as e políticos nos finais da década de oitenta, início da década de noventa do século XX. Nesta análise, será dada ênfase às investigações e quadros teóricos produzidos e às medidas legislativas e políticas educativas no domínio do tratamento da diferença cultural dentro do sistema educativo português.The aim of this article consists in attempting to transmit a sociologically informed view in what the Portuguese situation in the field of public policies and research related to the educational system and (im)migration are concerned, that is, in attempting to construct an intercultural education. In this way, a descriptive and comprehensiveinterpretative analysis of the evolution of this problem in Portugal will be realized, since the latter became an object of reflection on the part of researchers and politicians towards the end of the 80s, the beginning of the 90s of the XXth century. In this analysis, emphasis will be given on the research and theoretical frameworks produced and on the legislative measures and educational policies in the field of treating cultural difference in the Portuguese educational system
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