3,043 research outputs found

    Extraordinary transverse magneto-optical Kerr effect in a superlens

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    It has been shown that a slab of a negative index material can behave as a superlens enhancing the imaging resolution beyond the wavelength limit. We show here that if such a slab possesses in addition some magneto-optical activity, it could act as an ideal optical filter and exhibit an extraordinary transverse magneto-optical Kerr effect. Moreover, we show that losses, which spoil the imaging resolution of these lenses, are a necessary ingredient to observe this effect.Comment: 5 pages, 6 figure

    Equity problems in the honduran educative system

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    Los actuales esfuerzos por mejorar la equidad de la educación en América Latina en general y en Honduras en particular, en el contexto de las profundas desigualdades sociales prevalecientes, se enfocan en la búsqueda de intervenciones que, gestionando los escasos recursos disponibles, disminuyan las brechas en el acceso y el desempeño escolar asociados a las diferencias por estratos socioeconómicos, grupos étnicos, género, o por región de residencia de los estudiantes. El presente artículo plantea una panorámica de las brechas de equidad que padece el sistema educativo hondureño, tanto en relación con el acceso como respecto a los niveles de aprendizaje alcanzados por los alumnos en función del estrato socioeconómico del que provienen, de la región (urbano-rural) en que residen y del género o grupo étnico al que pertenecen. La gran conclusión es que, tal como viene operando el sistema educativo hondureño, está reproduciendo e incluso acentuando, las amplias brechas sociales preexistent

    Evaluation of the quality and antioxidant capacity of woodland strawberry biotypes in Sicily

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    In Sicily, the woodland strawberry grows wild in forest glades in the Madonie and Nebrodi mountains and on Mount Etna. In this region, the main cultivated clone is Fragolina di Ribera, named after the towns where the crop originally developed. The cultivated woodland strawberry is different from its wild counterparts not only in vegetative vigour and size, but also in organoleptic quality. Fragolina di Ribera has always been described with sensory analysis as one of the best Sicilian berry. This study was carried out in Sicily and compared two June-bearing Fragaria vesca: Fragolina di Ribera and Fragolina di Maletto, and an everbearing variety Regina delle Valli, in order to determine the production, quality and nutraceutical characteristics of the fruit. Research results provided useful, more detailed information on those fruit compounds with nutritional and health benefits and the June-bearing Fragolina di Ribera was found not only to produce highly sweet, bright red fruits, but also fruits with high antioxidant capacity and high ascorbic acid, polyphenol and anthocyanin levels

    Enzyme prodrug therapy achieves site-specific, personalized physiological responses to the locally produced nitric oxide

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    Nitric oxide (NO) is a highly potent but short-lived endogenous radical with a wide spectrum of physiological activities. In this work, we developed an enzymatic approach to the site-specific synthesis of NO mediated by biocatalytic surface coatings. Multilayered polyelectrolyte films were optimized as host compartments for the immobilized β-galactosidase (β-Gal) enzyme through a screen of eight polycations and eight polyanions. The lead composition was used to achieve localized production of NO through the addition of β-Gal–NONOate, a prodrug that releases NO following enzymatic bioconversion. The resulting coatings afforded physiologically relevant flux of NO matching that of the healthy human endothelium. The antiproliferative effect due to the synthesized NO in cell culture was site-specific: within a multiwell dish with freely shared media and nutrients, a 10-fold inhibition of cell growth was achieved on top of the biocatalytic coatings compared to the immediately adjacent enzyme-free microwells. The physiological effect of NO produced via the enzyme prodrug therapy was validated ex vivo in isolated arteries through the measurement of vasodilation. Biocatalytic coatings were deposited on wires produced using alloys used in clinical practice and successfully mediated a NONOate concentration-dependent vasodilation in the small arteries of rats. The results of this study present an exciting opportunity to manufacture implantable biomaterials with physiological responses controlled to the desired level for personalized treatment

    The Zero-Removing Property and Lagrange-Type Interpolation Series

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    The classical Kramer sampling theorem, which provides a method for obtaining orthogonal sampling formulas, can be formulated in a more general nonorthogonal setting. In this setting, a challenging problem is to characterize the situations when the obtained nonorthogonal sampling formulas can be expressed as Lagrange-type interpolation series. In this article a necessary and sufficient condition is given in terms of the zero removing property. Roughly speaking, this property concerns the stability of the sampled functions on removing a finite number of their zeros

    Hydrogymnastics training program on physical fitness in elderly women

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    Se evaluó un programa de entrenamiento de hidrogimnasia sobre las capacidades físicas en 26 adultas mayores (grupo experimental n=16, grupo control n=10), determinadas mediante el protocolo senior fitness test, la hidrogimnasia fue 5 veces por semana por 12 semanas, con ejercicios aeróbicos del 50%-60% de la FCmáx. Se utilizó ANOVA 2x2, indicando interacción significativa (p=0.052) entre grupos y mediciones en la prueba de resistencia a la fuerza en extremidades inferiores, la prueba de agilidad de 2.4 metros tuvo interacción significativa (p≤0.01) entre grupos y mediciones, las pruebas de capacidad aeróbica step test de 2 minutos (p=0.02) y caminar 6 minutos indicaron interacción significativa entre grupos y mediciones (p=0.50); Se infiere que la hidrogimnasia en las adultas mayores participantes es eficaz en la mejora de las capacidades físicas principalmente aeróbicas, de resistencia a la fuerza y agilidad de miembros inferioresThe aim of this study was to evaluate the effect of a hydrogymnastics training program on physical fitness in 26 elderly women (experimental group n=16, control group n=10). The physical fitness was determined by the senior fitness test protocol, the hydrogymnastics consisted in aerobic exercise at 50%-60% of maximum heart rate, 5 times a week in a period of 12 weeks. ANOVA 2x2 as statistical test was used, indicating statistically significant interaction (p=0.052) between groups and measurements on test strength endurance in the legs by squatting on chair in 30 s, agility test 2.4 meters was significant interaction (p≤0.01) between groups and measures, testing aerobic capacity test step 2 minutes (p=0.02) and six minutes walk indicated significant interaction between groups and measurements (p=0.50), the results shown that hydrogymnastics in the elderly women participants was effective improving endurance, strength and agility mainly in leg

    Colaboración docente para diseñar materiales de Ciencia y Tecnología Culinaria y, Salud Pública

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    En el presente trabajo se han diseñado materiales de trabajo para utilizar en las asignaturas de Ciencia y Tecnología Culinaria y, Salud Pública del Grado en Nutrición Humana y Dietética (NHyD). Estos materiales han permitido obtener valoraciones nutricionales de platos típicos de la Comunidad Valenciana como son arroces y legumbres y, a partir de estas valoraciones hacer comparaciones nutricionales entre dichos platos. Por otro lado, se ha trabajado el tema de los tamaños de ración estimados por los alumnos para personas adultas y sanas, también se ha realizado una comparación entre de tamaños entre recetas semejantes. Estos conocimientos previos se han aplicado a una asignatura que se imparte posteriormente en el Grado de NHyD que es Salud Pública. En dicha asignatura, se han diseñado unos cuestionarios para averiguar si los tamaños de ración estimados por los alumnos y por familiares son muy diferentes. Los resultados obtenidos muestran que la realización de la valoración nutricional de platos por parte de los alumnos permite añadir conocimientos a los alumnos que no se encuentran en bibliografía y, además también permiten concienciar de la importancia que tiene la educación a los pacientes en cuanto a la importancia que puede tener el tamaño de ración que se consuma

    Regulation of neutrophil senescence by microRNAs

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    Neutrophils are rapidly recruited to sites of tissue injury or infection, where they protect against invading pathogens. Neutrophil functions are limited by a process of neutrophil senescence, which renders the cells unable to respond to chemoattractants, carry out respiratory burst, or degranulate. In parallel, aged neutrophils also undergo spontaneous apoptosis, which can be delayed by factors such as GMCSF. This is then followed by their subsequent removal by phagocytic cells such as macrophages, thereby preventing unwanted inflammation and tissue damage. Neutrophils translate mRNA to make new proteins that are important in maintaining functional longevity. We therefore hypothesised that neutrophil functions and lifespan might be regulated by microRNAs expressed within human neutrophils. Total RNA from highly purified neutrophils was prepared and subjected to microarray analysis using the Agilent human miRNA microarray V3. We found human neutrophils expressed a selected repertoire of 148 microRNAs and that 6 of these were significantly upregulated after a period of 4 hours in culture, at a time when the contribution of apoptosis is negligible. A list of predicted targets for these 6 microRNAs was generated from http://mirecords.biolead.org and compared to mRNA species downregulated over time, revealing 83 genes targeted by at least 2 out of the 6 regulated microRNAs. Pathway analysis of genes containing binding sites for these microRNAs identified the following pathways: chemokine and cytokine signalling, Ras pathway, and regulation of the actin cytoskeleton. Our data suggest that microRNAs may play a role in the regulation of neutrophil senescence and further suggest that manipulation of microRNAs might represent an area of future therapeutic interest for the treatment of inflammatory disease

    Development and Test of High Temperature Surface Acoustic Wave Gas Sensors

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    The demand for sensors in hostile environments, such as power plant environments, exhaust systems and high-temperature metallurgy environments, has risen over the past decades in a continuous attempt to increase process control, improve energy and process efficiency in production, reduce operational and maintenance costs, increase safety, and perform condition-based maintenance in equipment and structures operating in high-temperature, harsh-environment conditions. The increased reliability, improved performance, and development of new sensors and networks with a multitude of components, especially wireless networks, are the target for operation in harsh environments. Gas sensors, in particular hydrogen gas sensors, operating above 200°C are required in the instrumentation, process control and general safety of a number of industries including coal, natural gas, and nuclear power generation facilities, the aerospace and automotive industries, metallurgical production and defense-related applications. The surface acoustic wave (SAW) platform is a particularly promising option for high-temperature, harsh-environment gas sensing applications since the platform exhibits advantages, such as battery-free and wireless operation, small size, possibility for scale production using well-developed technologies from the semiconductor industry, and low cost of installation and operation. In this work, one-port SAW resonators (SAWRs) operating along five different orientations on a commercially available langasite (LGS) wafer were designed, fabricated, and used as high-temperature H2 sensors. Two of the selected orientations were predicted and confirmed to have temperature-compensated operation above 150°C. A gas sensor test setup was developed, capable of gas cycling between N2, O2 and N2/H2 mixtures under extended high-temperature periods (up to 650°C for over 20 hours). Thin film Pt-Al2O3 was used as the electrode material for transducers and reflectors capable of high-temperature operation, and also as H2 sensing film. In addition, yttria-stabilized zirconia (YSZ) thin films with Pt decoration were tested as sensing films aimed to enhance the SAWR sensor response to H2. The SAW devices were monitored in excess of 1700 hours in real-time during gas cycling sequences up to 600°C, leading to the following findings: i) the Pt-Al2O3 electrodes performed better for H2 sensing than the Pt-decorated YSZ sensing film, showing as much as 50% higher frequency response variation in the 200°C to 400°C range; ii) different crystallographic orientations operating on the same LGS wafer experienced different responses to H2 exposures up to 500°C; iii) the surface oxidation state of the SAWR sensors was shown to have an important impact on subsequent H2 exposure responses. Additionally, the feasibility of a sensor system capable of detecting H2 and determining the ambient temperature simultaneously by employing two different SAWR sensors operating along different LGS orientations was examined. Finally, wireless interrogation of a SAWR sensor was successful within the gas cycling test fixture, and successful wireless H2 detection was achieved above 400°C
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