392 research outputs found

    DISTRIBUTIONS ISOTOPIQUES DES PRODUITS DE TRANSFERTS TRÈS INÉLASTIQUES ENTRE IONS LOURDS

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    On compare les distributions isotopiques expérimentales des produits de transfert très inélastiques obtenus par les réactions 40Ca (284 MeV) + 40Ca et 40Ar (295 MeV) + 232Th

    Self-assembly in solution of a reversible comb-shaped supramolecular polymer

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    We report a single step synthesis of a polyisobutene with a bis-urea moiety in the middle of the chain. In low polarity solvents, this polymer self-assembles by hydrogen bonding to form a combshaped polymer with a central hydrogen bonded backbone and polyisobutene arms. The comb backbone can be reversibly broken, and consequently, its length can be tuned by changing the solvent, the concentration or the temperature. Moreover, we have proved that the bulkiness of the side-chains have a strong influence on both the self-assembly pattern and the length of the backbone. Finally, the density of arms can be reduced, by simply mixing with a low molar mass bis-urea

    Protective role of vitamin B6 (PLP) against DNA damage in Drosophila models of type 2 diabetes

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    Growing evidence shows that improper intake of vitamin B6 increases cancer risk and several studies indicate that diabetic patients have a higher risk of developing tumors. We previously demonstrated that in Drosophila the deficiency of Pyridoxal 5' phosphate (PLP), the active form of vitamin B6, causes chromosome aberrations (CABs), one of cancer prerequisites, and increases hemolymph glucose content. Starting from these data we asked if it was possible to provide a link between the aforementioned studies. Thus, we tested the effect of low PLP levels on DNA integrity in diabetic cells. To this aim we generated two Drosophila models of type 2 diabetes, the first by impairing insulin signaling and the second by rearing flies in high sugar diet. We showed that glucose treatment induced CABs in diabetic individuals but not in controls. More interestingly, PLP deficiency caused high frequencies of CABs in both diabetic models demonstrating that hyperglycemia, combined to reduced PLP level, impairs DNA integrity. PLP-depleted diabetic cells accumulated Advanced Glycation End products (AGEs) that largely contribute to CABs as α-lipoic acid, an AGE inhibitor, rescued not only AGEs but also CABs. These data, extrapolated to humans, indicate that low PLP levels, impacting on DNA integrity, may be considered one of the possible links between diabetes and cancer

    Guías para aplicación de Normas de Calidad para los procesos de Ingeniería de Software en productos desarrollados con Lenguajes de Programación Open Source: relevamiento y aplicación en PYMES de la zona de influencia de la UNER Concordia

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    El Software Libre u Open Source es una forma de licenciamiento que da a los usuarios la libertad de compartir, estudiar y modificar el software. Este paradigma ha tenido impedimentos para su adopción en ambientes empresariales y comerciales debido a concepciones en muchos casos erróneas. En la actualidad, varias de estas ideas se han desmitificado, brindando una dosis de realidad a las oportunidades y obstáculos de esta filosofía. Esto se manifiesta en una evolución y aceptación paulatina de la adopción de software libre como temática central en la Ingeniería de Software. Este contexto plantea la necesidad de contar con estándares de medición y certificación de calidad específicos para productos de Software Libre y de las competencias y desempeño de empresas y profesionales que utilicen, generen y promocionen el Software Libre. Este proyecto de investigación propuso la formulación de marcos metodológicos y modelos de certificación relacionados con software libre y lenguajes de programación open source, tanto para empresas usuarias como desarrolladoras. De esta manera, se pretendió dar valor agregado y ventaja competitiva a las empresas y profesionales que utilicen, desarrollen y/o promuevan el Software Libre y las tecnologías abiertas

    Contribución al desarrollo de ciudades sustentables en la costa del Río Uruguay: diseño de indicadores de responsabilidad y sustentabilidad para gobiernos locales

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    En la última década y especialmente en los últimos años, la evolución en materia de medición y comunicación de información sobre la gestión en material social y ambiental, ha sido fructífera y de un gran impacto mundial. El Proyecto de Investigación PID 7056 con sede en la Universidad Nacional de Entre Ríos, se propuso desarrollar un sistema de indicadores de responsabilidad social y sustentabilidad (RSyS) para gobiernos locales del corredor del Río Uruguay en la provincia de Entre Ríos. Para ello se recurrió al análisis de los principales marcos de referencia en materia de medición y comunicación, a la consulta a expertos referentes y a la indagación de los sistemas de información de los municipios de dicho corredor. Entre los resultados más destacados, pueden mencionarse que ninguno de los modelos ofrece por sí solo, un marco integral que incorpore diferentes materias para la medición de la gestión; a su vez, los municipios estudiados cuentan con una situación muy dispar, fundamentalmente en relación a los sistemas de información que poseen, su grado de integración e inclusión de información socio-ambiental,  y la existencia de áreas específicas dentro de su estructura; encontrándose, los de mayor envergadura, en una posición ventajosa para avanzar en la implementación de un sistema de indicadores de sustentabilidad

    A Switch in the Control of Growth of the Wing Imaginal Disks of Manduca sexta

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    Background: Insulin and ecdysone are the key extrinsic regulators of growth for the wing imaginal disks of insects. In vitro tissue culture studies have shown that these two growth regulators act synergistically: either factor alone stimulates only limited growth, but together they stimulate disks to grow at a rate identical to that observed in situ. It is generally thought that insulin signaling links growth to nutrition, and that starvation stops growth because it inhibits insulin secretion. At the end of larval life feeding stops but the disks continue to grow, so at that time disk growth has become uncoupled from nutrition. We sought to determine at exactly what point in development this uncoupling occurs. Methodology: Growth and cell proliferation in the wing imaginal disks and hemolymph carbohydrate concentrations were measured at various stages in the last larval instar under experimental conditions of starvation, ligation, rescue, and hormone treatment. Principal Findings: Here we show that in the last larval instar of M. sexta, the uncoupling of nutrition and growth occurs as the larva passes the critical weight. Before this time, starvation causes a decline in hemolymph glucose and trehalose and a cessation of wing imaginal disks growth, which can be rescued by injections of trehalose. After the critical weight the trehalose response to starvation disappears, and the expression of insulin becomes decoupled from nutrition. After the critical weight the wing disks loose their sensitivity to repression by juvenile hormone, and factors from the abdomen, bu

    Supramolecular thermoplastics and thermoplastic elastomer materials with self-healing ability based on oligomeric charged triblock copolymers

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    Supramolecular polymeric materials constitute a unique class of materials held together by non-covalent interactions. These dynamic supramolecular interactions can provide unique properties such as a strong decrease in viscosity upon relatively mild heating, as well as self-healing ability. In this study we demonstrate the unique mechanical properties of phase-separated electrostatic supramolecular materials based on mixing of low molar mass, oligomeric, ABA-triblock copolyacrylates with oppositely charged outer blocks. In case of well-chosen mixtures and block lengths, the charged blocks are phase separated from the uncharged matrix in a hexagonally packed nanomorphology as observed by transmission electron microscopy. Thermal and mechanical analysis of the material shows that the charged sections have a T-g closely beyond room temperature, whereas the material shows an elastic response at temperatures far above this T-g ascribed to the electrostatic supramolecular interactions. A broad set of materials having systematic variations in triblock copolymer structures was used to provide insights in the mechanical properties and and self-healing ability in correlation with the nanomorphology of the materials
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