724 research outputs found

    Hybrid materials based on polyethylene and MCM-41 microparticles functionalized with silanes: catalytic aspects of in situ polymerization, crystalline features and mechanical properties

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    New nanocomposites based on polyethylene have been prepared by in situ polymerization of ethylene in presence of mesoporous MCM-41. The polymerization reactions were performed using a zirconocene catalyst either under homogenous conditions or supported onto mesoporous MCM-41 particles, which are synthesized and decorated post-synthesis with two silanes before polymerization in order to promote an enhanced interfacial adhesion. The existence of polyethylene chains able to crystallize within the mesoporous channels in the resulting nanocomposites is figured out from the small endothermic process, located at around 80 C, on heating calorimetric experiments, in addition to the main melting endotherm. These results indicate that polyethylene macrochains can grow up during polymerization either outside or inside the MCM-41 channels, these keeping their regular hexagonal arrangements. Mechanical response is observed to be dependent on the content in mesoporous MCM-41 and on the crystalline features of polyethylene. Accordingly, stiffness increases and deformability decreases in the nanocomposites as much as MCM-41 content is enlarged and polyethylene amount within channels is raised. Ultimate mechanical performance improves with MCM-41 incorporation without varying the final processing temperature

    Ownership and control in a competitive industry

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    We study a differentiated product market in which an investor initially owns a controlling stake in one of two competing firms and may acquire a non-controlling or a controlling stake in a competitor, either directly using her own assets, or indirectly via the controlled firm. While industry profits are maximized within a symmetric two product monopoly, the investor attains this only in exceptional cases. Instead, she sometimes acquires a noncontrolling stake. Or she invests asymmetrically rather than pursuing a full takeover if she acquires a controlling one. Generally, she invests indirectly if she only wants to affect the product market outcome, and directly if acquiring shares is profitable per se. --differentiated products,separation of ownership and control,private benefits of control

    An Integrated TCGA Pan-Cancer Clinical Data Resource to Drive High-Quality Survival Outcome Analytics

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    For a decade, The Cancer Genome Atlas (TCGA) program collected clinicopathologic annotation data along with multi-platform molecular profiles of more than 11,000 human tumors across 33 different cancer types. TCGA clinical data contain key features representing the democratized nature of the data collection process. To ensure proper use of this large clinical dataset associated with genomic features, we developed a standardized dataset named the TCGA Pan-Cancer Clinical Data Resource (TCGA-CDR), which includes four major clinical outcome endpoints. In addition to detailing major challenges and statistical limitations encountered during the effort of integrating the acquired clinical data, we present a summary that includes endpoint usage recommendations for each cancer type. These TCGA-CDR findings appear to be consistent with cancer genomics studies independent of the TCGA effort and provide opportunities for investigating cancer biology using clinical correlates at an unprecedented scale. Analysis of clinicopathologic annotations for over 11,000 cancer patients in the TCGA program leads to the generation of TCGA Clinical Data Resource, which provides recommendations of clinical outcome endpoint usage for 33 cancer types

    Reconstructing Neutrino Properties from Collider Experiments in a Higgs Triplet Neutrino Mass Model

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    We extend the minimal supersymmetric standard model with bilinear R-parity violation to include a pair of Higgs triplet superfields. The neutral components of the Higgs triplets develop small vacuum expectation values (VEVs) quadratic in the bilinear R-parity breaking parameters. In this scheme the atmospheric neutrino mass scale arises from bilinear R-parity breaking while for reasonable values of parameters the solar neutrino mass scale is generated from the small Higgs triplet VEVs. We calculate neutrino masses and mixing angles in this model and show how the model can be tested at future colliders. The branching ratios of the doubly charged triplet decays are related to the solar neutrino angle via a simple formula.Comment: 19 pages, 4 figures; one formula corrected, two author's names corrected; some explanatory comments adde

    Tracking a recent horizontal transfer event: The P-element reaches Brazilian populations of Drosophila simulans

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    O elemento P “recortar e colar” presente em alguns dípteros ilustra duas importantes habilidades de elementos transponíveis: mover-se dentro dos genomas e ser transmitido entre espécies não acasaladoras, um fenômeno conhecido como transferência horizontal de transposon (HTT). Estudos recentes relataram um HTT do elemento P de Drosophila melanogaster para D. simulans. Os elementos P apareceram pela primeira vez em amostras europeias de D. simulans coletadas em 2006 e se espalharam por várias populações da Europa, África, América do Norte e Japão em sete anos. No entanto, nenhum elemento P foi encontrado em populações sul-americanas de D. simulans coletadas entre 2002 e 2009. Investigamos a presença do elemento P em D. simulans coletados em cinco localidades brasileiras entre 2018 e 2019, usando uma combinação de metodologias como PCR, sequenciamento de DNA e FISH nos cromossomos. Nossos experimentos revelaram a presença do elemento P em todos os indivíduos amostrados nas cinco localidades. O número de elementos P por indivíduo variou de 11 a 20 cópias e também foram observadas cópias truncadas. Ao todo, nossos resultados mostraram que a invasão do elemento P em D. simulans está em um estágio avançado no Brasil e, juntamente com outros estudos recentes, confirmam a notável e rápida invasão de elementos P nas populações mundiais de D. simulans.The “cut-and-paste” P-element present in some Diptera illustrates two important transposable elements abilities: to move within genomes and to be transmitted between non-mating species, a phenomenon known as horizontal transposon transfer (HTT). Recent studies reported a HTT of the P-element from Drosophila melanogaster to D. simulans. P-elements first appeared in D. simulans European samples collected in 2006 and spread across several populations from Europe, Africa, North America and Japan within seven years. Nevertheless, no P-element was found in South American populations of D. simulans collected between 2002 and 2009. We investigated the presence of the P-element in D. simulans collected in five Brazilian localities between 2018 and 2019, using a combination of methodologies such as PCR, DNA sequencing and FISH on chromosomes. Our experiments revealed the presence of the P-element in all sampled individuals from the five localities. The number of P-elements per individual varied from 11 to 20 copies and truncated copies were also observed. Altogether, our results showed that P-element invasion in D. simulans is at an advanced stage in Brazil and, together with other recent studies, confirms the remarkable rapid invasion of P-elements across worldwide D. simulans populations.CNPq - Conselho Nacional de Desenvolvimento Científico e Tecnológic

    Informatização do museu de geociências

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    Current and Future Prospects of Nitro-compounds as Drugs for Trypanosomiasis and Leishmaniasis

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    Interest in nitroheterocyclic drugs for the treatment of infectious diseases has undergone a resurgence in recent years. Here we review the current status of monocyclic and bicyclic nitroheterocyclic compounds as existing or potential new treatments for visceral leishmaniasis, Chagas' disease and human African trypanosomiasis. Both monocyclic (nifurtimox, benznidazole and fexinidazole) and bicyclic (pretomanid (PA-824) and delamanid (OPC-67683)) nitro-compounds are prodrugs, requiring enzymatic activation to exert their parasite toxicity. Current understanding of the nitroreductases involved in activation and possible mechanisms by which parasites develop resistance is discussed along with a description of the pharmacokinetic / pharmacodynamic behaviour and chemical structure-activity relationships of drugs and experimental compounds.</p

    Combined aerobic and resistance training: are there additional benefits for older hypertensive adults?

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    OBJECTIVES: The objective of this study was to compare the effects of a combination of aerobic and resistance training to those of isolated aerobic training on blood pressure, body composition, and insulin sensitivity in hypertensive older adults. METHOD: Forty-four patients were randomly assigned to the aerobic group, resistance and aerobic group, and control group. Before and after 10 weeks, the following data were obtained: 24-hour ambulatory blood pressure data, abdominal circumference, waist circumference, body mass index, lean mass, fat mass, and insulin sensitivity. The study was conducted with 3 training sessions per week. RESULTS: Comparison revealed significant reductions in the body mass index, abdominal and waist circumferences, and ambulatory blood pressure (24-hour, wakefulness and sleep systolic/diastolic blood pressures) in both the aerobic group and the resistance and aerobic (combined) group. The fat mass only changed in the combined group. There was no difference in the insulin sensitivity in any group. CONCLUSIONS: The combined treatment and aerobic treatment alone were equally effective in reducing the blood pressure, body mass index, and abdominal and waist circumferences, although the addition of the resistance component also helped reduce the fat mass

    Uso de Tai Chi para la salud del adulto mayor: revisión bibliográfica

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    Introducción: La población de adultos mayores está incrementando y se observa la necesidad emergente de implementar estrategias dirigidas a recuperar o conservar su salud para que puedan gozar de una vejez plena. Técnicas como el Tai Chi podrían contribuir, ya que han mostrado tener múltiples beneficios para quien la práctica, tales como mejoras en la concentración, memoria, marcha, equilibrio, reducción del riesgo de caídas, fortalecimiento del sistema cardiovascular, reducción del estrés y la depresión, entre otros beneficios. Objetivo: Analizar la evidencia científica del uso del Tai Chi para conservar la salud del adulto mayor. Desarrollo: Revisión bibliográfica realizada durante el periodo 2013-2019 en distintas bases de datos como: Pubmed, Dialnet, SciELO, LILACS, ScienceDirect y Google Académico. Se utilizaron las palabras Tai Chi Chuan, Tai Ji Quan, Tai Chi. Aplicando los criterios de elegibilidad se seleccionaron 29 artículos. Resultados: Gran porcentaje de los artículos revisados estudian la atención de síntomas físicos que deterioran la movilidad del adulto mayor, sin embargo, también se encontraron investigaciones dirigidas a la parte psicológica, como el estrés, la ansiedad, el insomnio, la depresión y el enfado-tensión, en las cuales la práctica del Tai Chi demostró mejoría. Conclusiones: El Tai Chi es una terapia alternativa para prevenir y conservar la salud del adulto mayor, fácil de aprender y de bajo costo. En la revisión bibliográfica realizada no se reportan reacciones adversas durante ni después de la práctica de la técnica; el profesional de enfermería puede recomendarla ampliamente para ser implementada como un cuidado dirigido al adulto mayor

    Design and validation of the INCUE questionnaire: assessment of primary healthcare nurses’ basic training needs in palliative care

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    Many instruments have been created to measure knowledge and attitudes in palliative care. However, not only is it important to acquire knowledge, but also that this knowledge should reach patients and their relatives through application in clinical practice. This study aimed to develop and psychometrically test the INCUE questionnaire (Investigación Cuidados Enfermeros/Investigation into Nurses’ Care Understanding of End-of-Life) to assess the basic training needs of primary or home healthcare nurses in palliative care. A questionnaire was developed based on the classical theory of tests and factor analysis models. Initially, 18 experts developed 67 items in two blocks and determined content validity by two rounds of expert panels. Exploratory factor analysis and reliability testing were conducted with a non-probabilistic sample of 370 nurses. Some items were observed to have very low homogeneity indices or presented convergence problems and were eliminated. Questionnaire reliability was 0.700 in the theoretical block (KR20 Index) and 0.941 in the practical block (Cronbach’s alpha). The model converges and shows an adequate fit, specifically CFI = 0.977, TLI = 0.977 and RMSEA = 0.05. The correlation between the two factors in the model is ρ = 0.63. The questionnaire objectively evaluates primary or home healthcare nurses’ knowledge of palliative care and its practical application, thereby facilitating more efficient training plans
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