185 research outputs found

    Effects of pulsed electric field on the viscoelastic properties of potato tissue

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    We have investigated whether transient permeabilization caused by the application of pulsed electric field would give rise to transient changes in the potato tissue viscoelastic properties. Potato tissue was subjected to nominal field strengths (E) ranging from 30 to 500 V/cm, with a single rectangular pulse of 10−5, 10−4, or 10−3 s. The changes on the viscoelastic properties of potato tissue during pulsed electric fields (PEF) were monitored through small amplitude oscillatory dynamic rheological measurements. The elastic (G′) and viscous moduli (G″) were measured every 30 s after the delivery of the pulse and the loss tangent change (tan-δ) was calculated. The results were correlated with measurements of changes on electrical resistance during the delivery of the pulse. Results show a drastic increase of tan-δ in the first 30 s after the application of the pulse, followed by a decrease 1 min after pulsation. This response is strongly influenced by pulsing conditions and is independent of the total permeabilization achieved by the pulse. Our results, supported by similar measurements on osmotically dehydrated control samples, clearly show that PEF causes a rapid change of the viscoelastic properties of the tissue that could be attributed to a partial loss in turgor pressure. This would be an expected consequence of electroporation. The recovery of tan-δ to values similar to those before pulsation strongly suggests recovery of cell membrane properties and turgor, pointing at reversible permeabilization of the cells. A slight increase of stiffness traduced by a negative change of tan-δ after application of certain PEF conditions may also give an indication of events occurring on cell wall structure due to stress responses. This study set the basis for further investigations on the complex cell stress physiology involving both cell membrane functional properties and cell wall structure that would influence tissue physical properties upon PEF application.Fundação para a Ciência e a Tecnologia (FCT

    Properties of natural reinforced earth-bases composites: advantages and drawbacks with synthetic reinforcemen

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    The increase of awareness of the need to improve the sustainability of the construction industry and the concurrent development of "Green Technologies" has led to the raise of bio-composite materials with natural reinforcements for building applications. This process has involved the revival of the interest in the use of natural reinforced earth materials. Of these, the earthy materials with natural or synthetic reinforcements belong to a field that hasn’t been very much developed beyond traditional or emergency applications in architecture. The most determining aspect to develop products and systems based on reinforced earth based composites is the huge diversity on its physical and mechanical properties. Composites properties depend on diverse variables, among which are those concerning the type of soil and ground grain, type of reinforcement fibers (natural or synthetic), natural conditions in which were obtained, processing methods and characteristics of the possible matrices used as stabilizers. This paper aims for a comprehensive review of literature of the available natural or synthetic reinforced earth based composites. General characteristics of the mainly used reinforcement agents depending on its origin, type, composition, structure, chemical composition and mechanical properties of the studied material (animal hair, jute, sisal, coir, flax, hemp, pineapple fiber, bamboo, rice husk, oil palm, etc). Moreover, different processing methods to improve physical and chemical characteristics, together with processing systems and factors affecting the production and characteristics of these composites will be considered (moisture content, type of reinforcement, ratios, distribution, coupling agent, etc.). The present review is intended to update the overview the research of these kind products as well as to outline the main objectives and issues addressed in these current lines of research

    Exploring metabolic responses of potato tissue induced by electric pulses

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    In this study, we investigated the metabolic responses of potato tissue induced by pulsed electric field (PEF). Potato tissue was subjected to field strengths ranging from 30 to 500 V/cm, with a single rectangular pulse of 10 μs, 100 μs, or 1 ms. Metabolic responses were monitored using isothermal calorimetry, changes on electrical resistance during the delivery of the pulse, as well as impedance measurements. Our results show that the metabolic response involves oxygen consuming pathways as well as other unidentified events that are shown to be insensitive to metabolic inhibitors such as KCN and sodium azide. The metabolic response is strongly dependent on pulsing conditions and is independent of the total permeabilization achieved by the pulse. Evidence shows that calorimetry is a simple and powerful method for exploring conditions for metabolic stimulation, providing information on metabolic responses that can not be obtained from electrical measurements. This study set the basis for further investigations on defense-related consequences of PEF-induced stress.Sparbanksstiftelsen Färs & Frosta (Sweden).Fundação para a Ciência e a Tecnologia (FCT).Lund University (Sweden).Department of Cell and Organism Biology; Department of Plant Biochemistry

    The Poincaré problem, algebraic integrability and dicritical divisors

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    We solve the Poincaré problem for plane foliations with only one dicritical divisor. Moreover, in this case, we give a simple algorithm that decides whether a foliation has a rational first integral and computes it in the affirmative case. We also provide an algorithm to compute a rational first integral of prefixed genus g≠1 of any type of plane foliation F. When the number of dicritical divisors dic(F) is larger than 2, this algorithm depends on suitable families of invariant curves. When dic(F)=2, it proves that the degree of the rational first integral can be bounded only in terms of g , the degree of F and the local analytic type of the dicritical singularities of F.Supported by the Spain Ministry of Education MTM2012-36917-C03-03 and Univ. Jaume I P1-1B2012-04. The authors would like to thank the anonymous referee for his/her careful reading of the manuscript and for constructive suggestions that have improved it.Galindo Pastor, C.; Monserrat Delpalillo, FJ. (2014). The Poincaré problem, algebraic integrability and dicritical divisors. Journal of Differential Equations. 256(11):3614-3633. https://doi.org/10.1016/j.jde.2014.02.015S361436332561

    Degradation of buried ice and permafrost in the Veleta cirque (Sierra Nevada, Spain) from 2006 to 2013 as a response to recent climate trends

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    The Veleta cirque is located at the foot of the Veleta peak, one of the highest summits of the Sierra Nevada National Park (southern Spain). This cirque was the source of a glacier valley during the Quaternary cold periods. During the Little Ice Age it sheltered a small glacier, the most southerly in Europe, about which we have possessed written records since the 17th century. This glacier still had ice residues until the mid-20th century. This ice is no longer visible, but a residue persists along with discontinuous permafrost trapped under strata of rock blocks that make up an incipient rock glacier. From 2006 to 2013, this rock glacier was monitored by measurement of the temperature of the active layer, the degree of snow cover on the ground, movements of the body of the rock glacier and geophysical prospection inside it. The results show that the relict ice and trapped permafrost have been steadily declining. The processes that explain this degradation occur in chain, starting from the external radiation that affects the ground in summer, which is when the temperatures are higher. In effect, when this radiation steadily melts the snow on the ground, the thermal expansive wave advances into the heart of the active layer, reaching the ceiling of the frozen mass, which it then degrades and melts. In this entire linked process, the circulation of meltwaters fulfils a highly significant function, as they act as heat transmitters. The complementary nature of these processes explains the subsidence and continuous changes in the entire clastic pack and the melting of the frozen ceiling on which it rests. This happens in summer in just a few weeks. All these events, in particular the geomorphological ones, take place on the Sierra Nevada peaks within certain climate conditions that are at present unfavourable to the maintenance of snow on the ground in summer. These conditions could be related to recent variations in the climate, starting in the mid-19th century and most markedly since the second half of the 20th century. The work and results highlight the climate sensitivity of the peaks of the Sierra Nevada to the effect of climate change and its impact on the dynamics of ecosystems, which is a benchmark for evaluating the current evolution of landscapes of Mediterranean high mountains.We are grateful to the research projects 018/2007 of the Autonomous Organisation of National Parks and CSO2012-30681 from the Ministry of Economy and Competition

    Hacia la construcción de la plataforma integrada de información para el sector salud de México

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    Objetivo. Estandarizar técnica, funcional y operativamente los principales sistemas de información en salud de la Subsecretaria de Promoción y Prevención de la Salud de México (SPPS) de la Secretaría de Salud Federal (SSA). Metodología. Se realizó el diagnóstico de los sistemas de información de la SPPS y se priorizaron los hallazgos con base en los requerimientos y necesidades, para llevar a cabo las acciones de estandarización, mantenimiento y actualización. Resultados. Se evaluaron y realizaron mejoras a nueve sistemas de información, mismos que se encuentran operando de manera regular o en fase pre-operativa para el apoyo del monitoreo de programas preventivos.Sociedad Argentina de Informática e Investigación Operativ

    Hacia la construcción de la plataforma integrada de información para el sector salud de México

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    Objetivo. Estandarizar técnica, funcional y operativamente los principales sistemas de información en salud de la Subsecretaria de Promoción y Prevención de la Salud de México (SPPS) de la Secretaría de Salud Federal (SSA). Metodología. Se realizó el diagnóstico de los sistemas de información de la SPPS y se priorizaron los hallazgos con base en los requerimientos y necesidades, para llevar a cabo las acciones de estandarización, mantenimiento y actualización. Resultados. Se evaluaron y realizaron mejoras a nueve sistemas de información, mismos que se encuentran operando de manera regular o en fase pre-operativa para el apoyo del monitoreo de programas preventivos.Sociedad Argentina de Informática e Investigación Operativ

    Hacia la construcción de la plataforma integrada de información para el sector salud de México

    Get PDF
    Objetivo. Estandarizar técnica, funcional y operativamente los principales sistemas de información en salud de la Subsecretaria de Promoción y Prevención de la Salud de México (SPPS) de la Secretaría de Salud Federal (SSA). Metodología. Se realizó el diagnóstico de los sistemas de información de la SPPS y se priorizaron los hallazgos con base en los requerimientos y necesidades, para llevar a cabo las acciones de estandarización, mantenimiento y actualización. Resultados. Se evaluaron y realizaron mejoras a nueve sistemas de información, mismos que se encuentran operando de manera regular o en fase pre-operativa para el apoyo del monitoreo de programas preventivos.Sociedad Argentina de Informática e Investigación Operativ

    Multicenter prospective clinical study to evaluate children short-term neurodevelopmental outcome in congenital heart disease (children NEURO-HEART) : study protocol

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    Altres ajuts: RETICS funded by the PN 2018-2021 (Spain).Congenital heart disease (CHD) is the most prevalent congenital malformation affecting 1 in 100 newborns. While advances in early diagnosis and postnatal management have increased survival in CHD children, worrying long-term outcomes, particularly neurodevelopmental disability, have emerged as a key prognostic factor in the counseling of these pregnancies. Eligible participants are women presenting at 20 to < 37 weeks of gestation carrying a fetus with CHD. Maternal/neonatal recordings are performed at regular intervals, from the fetal period to 24 months of age, and include: placental and fetal hemodynamics, fetal brain magnetic resonance imaging (MRI), functional echocardiography, cerebral oxymetry, electroencephalography and serum neurological and cardiac biomarkers. Neurodevelopmental assessment is planned at 12 months of age using the ages and stages questionnaire (ASQ) and at 24 months of age with the Bayley-III test. Target recruitment is at least 150 cases classified in three groups according to three main severe CHD groups: transposition of great arteries (TGA), Tetralogy of Fallot (TOF) and Left Ventricular Outflow Tract Obstruction (LVOTO). The results of NEURO-HEART study will provide the most comprehensive knowledge until date of children's neurologic prognosis in CHD and will have the potential for developing future clinical decisive tools and improving preventive strategies in CHD. , on 4th December 2016 (retrospectively registered)
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