614 research outputs found

    Bonding energetics in alkaline metal alkoxides and phenoxides

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    The bonding energetics in a variety of alkaline metal, alkoxides and phenoxides, MOR, was investigated based on the corresponding enthalpies of formation in the crystalline state determined by reaction-solution calorimetry. The results obtained at 298.15 K were as follows: fHom (MOR, cr)/kJmol-1 = 382.7 ± 1.4 (LiOC6H5), 513.6 ± 2.5 (NaO-nC6H13), 326.4 ± 1.4 (NaOC6H5), 375.2 ± 3.4 (KOCH3), 434.5 ± 2.7 (KOC2H5), 467.1 ± 5.2 (KOnC3H7), 459.3 ± 2.1 (KO-nC4H9), 464.6 ± 5.7 (KO-tC4H9), 464.3 ± 2.5 (KO-nC6H13), 333.3 ± 3.1 (KOC6H5), 380.6 ± 2.9(RbOCH3), 434.1 ± 2.9 (RbOC2H5), 345.3 ± 2.9 (LiOC6H5), 379.1 ± 3.0 (CsOCH3), 432.3 ± 3.1 (CsOC2H5), 466.9 ± 5.0 (CsO-nC3H7), 461.3 ± 3.5 (CsO-nC4H9), 461.9 ± 2.5 (CsO-tC4H9), 349.2 ± 1.4 (CsOC6H5). These results together with revised fH om (MOR, cr) values from the literature, were used to derive a consistent set of lattice energies for the MOR compounds and discuss general trends in the structure-energetics relationship based on the Kapustinskii equation.Fundação para a Ciência e a Tecnologiainfo:eu-repo/semantics/publishedVersio

    Swinging Atwood's Machine: Experimental and Theoretical Studies

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    A Swinging Atwood Machine (SAM) is built and some experimental results concerning its dynamic behaviour are presented. Experiments clearly show that pulleys play a role in the motion of the pendulum, since they can rotate and have non-negligible radii and masses. Equations of motion must therefore take into account the inertial momentum of the pulleys, as well as the winding of the rope around them. Their influence is compared to previous studies. A preliminary discussion of the role of dissipation is included. The theoretical behaviour of the system with pulleys is illustrated numerically, and the relevance of different parameters is highlighted. Finally, the integrability of the dynamic system is studied, the main result being that the Machine with pulleys is non-integrable. The status of the results on integrability of the pulley-less Machine is also recalled.Comment: 37 page

    Impacts of climate changes on risk zoning for cowpea in the Amazonian tropical conditions

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    The climate risk zoning was carried out for cowpea cultivated in northeastern Amazonia, Pará state, Brazil. Système d’Analyse Régionale des Risques Agroclimatologiques (SARRA) crop model was used and calibrated from data obtained in field experiments conducted between 2013 and 2016 in Castanhal, state of Pará. Low climate risk areas were defined as those with water requirement satisfaction index (WRSI) greater than or equal to 0.5 during flowering and early grain development and less than 20 mm of total rainfall during grain maturation and harvest for at least 80% of the simulated sowings of the crop. Simulations of the current and future climate conditions were carried out with the regional climate modelling system version 4 (RegCM4) nested with the HadGEM2 global circulation model with RCP 4.5 IPCC-AR4 scenario. The results show that climate changes are likely to reduce the duration of the optimal period for sowing cowpea in the mentioned regioninfo:eu-repo/semantics/publishedVersio

    Motivation and physical fitness in old people participating in a hydro-gymnastics

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    Introduction: The purpose of the present investigation was to evaluate the motivations and the impact of the hydro-gymnastics in the physical fitness of old people involved in a 16 weeks exercise program. Methods: Participants were 83 old people doing a community hydro-gymnastics exercise program. Motivations were assessed using the Sport Activity Motivation Questionnaire and physical fitness was evaluated using the Functional Fitness Test battery, in two separate moments with a 16 weeks interval. The assumption of normality was checked using the Kolmogorov-Smirnov test. Wilcoxon test was used to compare the group in different time moments. Results: Regarding motivations to hydro-gymnastics the items that scored higher were: “need to exercise”, “be with friends”, “make new friends” and “fun”. In terms of physical fitness variation, improvements in average were found in practically all fitness test between the 1st and 2nd evaluation, with significant statistical differences in 3 of the 5 tests applied. Conclusions: Old people´s major motives to participate in hydro-gymnastics are related to the motivational dimensions of physical fitness, general affiliation and pleasure. Additionally, hydro-gymnastics exercise programs have a positive impact to improve physical fitness in old people and play a determinant role on health promotion and successful aging

    Microarray in clinical practice – utility vs complexity. Mixed phenotype of duplication 15q11.2q13.1 and deletion 16p11.2

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    Introduction: There’s a consensus to perform chromosomal microarray technique as first-tier clinical diagnostic test for individuals with developmental disabilities. However, given the complexity of clinical presentations, often several diagnostic methods are held before conducting microarray. Method: We report the case of a 5 year-old boy referred to Medical Genetics due to short stature, developmental disabilities and facial dysmorphic features. He was born from eutocic delivery after an uneventful pregnancy. He had psychomotor milestones delayed like sitting at 9 months and walking at 24 months, holding an immature broad-based gait. There was history of learning difficulties from both parents, and the mother has also short stature. On examination it was noted some facial dysmorphic features like high forehead, conical canines and rarefaction of the distal portion of the eyebrows. Due to the history of an episode of transient ataxia, and suspicion of an inherited metabolic disorder, he had already performed various analytical and imaging screenings, all normal. Results: Chromosomal microarray analysis revealed two pathogenic Copy Number Variants (CNV’s): 16p11.2 deletion and 15q11.2q13.1 duplication. The 15q11q13 microduplication syndrome (OMIM # 608636) is a very rare clinical entity with about 30 reported cases with maternal origin, and it is characterized by neurobehavioral disorder, hypotonia, cognitive impairment, epilepsy and short stature. The 16p11.2 microdeletion syndrome (OMIM # 613444) is also a rare clinical entity, with high penetrance, associated with obesity and developmental disabilities. Discussion: Despite the unquestionable utility of microarray, the correlation of the CNV's with the phenotype is often difficult by the rarity of these new microdeletion/duplication clinical entities. In this case the interpretation has increased difficulty because of the simultaneous existence of two distinct clinical entities. Segregation studies, which in the first step include parental analysis, are essential for genetic counseling and determining the risk of recurrence but also for a more accurate correlation genotype-phenotype

    Impacts of climate and land use changes on the hydrological and erosion processes of two contrasting Mediterranean catchments

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    The impacts of climate and land use changes on streamflow and sediment export were evaluated for a humid (São Lourenço) and a dry (Guadalupe) Mediterranean catchment, using the SWAT model. SWAT was able to produce viable streamflow and sediment export simulations for both catchments, which provided a baseline for investigating climate and land use changes under the A1B and B1 emission scenarios for 2071–2100. Compared to the baseline scenario (1971–2000), climate change scenarios showed a decrease in annual rainfall for both catchments (humid: − 12%; dry: − 8%), together with strong increases in rainfall during winter. Land use changes were derived from a socio-economic storyline in which traditional agriculture is replaced by more profitable land uses (i.e. corn and commercial forestry at the humid site; sunflower at the dry site). Climate change projections showed a decrease in streamflow for both catchments, whereas sediment export decreased only for the São Lourenço catchment. Land use changes resulted in an increase in streamflow, but the erosive response differed between catchments. The combination of climate and land use change scenarios led to a reduction in streamflow for both catchments, suggesting a domain of the climatic response. As for sediments, contrasting results were observed for the humid (A1B: − 29%; B1: − 22%) and dry catchment (A1B: + 222%; B1: + 5%), which is mainly due to differences in the present-day and forecasted vegetation types. The results highlight the importance of climate-induced land-use change impacts, which could be similar to or more severe than the direct impacts of climate change alone

    II Ciclo de Conferências : Conselho Técnico-Científico: temas atuais em investigação

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    A obra é constituída pelos resumos das comunicações apresentadas pelos docentes da Escola Superior Agrária do Instituto Politécnico de Castelo Branco e são referentes aos projetos de investigação nos quais estão envolvidos.O atual Conselho Técnico-Científico (CTC) da Escola Superior Agrária de Castelo Branco (ESACB) tomou posse em fevereiro de 2012, tendo decidido dar continuidade ao ciclo de conferências iniciado pelo CTC anterior. Os trabalhos de Investigação, Inovação e Experimentação que foram apresentados demonstram não só o dinamismo e a ligação com a comunidade, como também a preocupação na identificação e resolução de problemas, que acrescentem valor aos produtos e processos que se situam no âmbito das competências desta Escola. Sendo este um objetivo prioritário da missão do IPCB/ESA, a divulgação destas conferências permite chegar a um público mais alargado e abrir caminhos para a concretização de novos projetos, que contribuam de forma efetiva para o desenvolvimento e aumento da competitividade da região e do país
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