Integridade estrutural de compósitos laminados em fibra de carbono sujeitos a diferentes taxas de desgaste e absorção de água : protótipo de máquina de testes

Trabalho final de mestrado para obtenção do grau de Mestre em Engenharia MecânicaDesde sempre no panorama do ciclismo de alta competição se fizeram todos os esforços para melhorar os resultados dos atletas. Grande parte destes trabalhos está no desenvolvimento das bicicletas e seus componentes. A empresa Morphis Composites que está em fase de desenvolvimento de carretos de desviador em fibra de carbono. Estando estes componentes em material compósito laminado expostos à atmosfera, poderá estar em causa a sua integridade estrutural pois sabe-se que irão absorver água por difusão e se vão desgastar de forma diferente de carretos de outros materiais. Tudo isto poderá levar ao aumento do seu atrito na transmissão, sendo que é necessária a criação de meios para a avaliação desta temática. No presente trabalho faz-se o projecto e construção de um protótipo para medição de atrito em transmissões de bicicleta. Inclui-se uma breve pesquisa bibliográfica sobre correntes de rolos industriais e de ciclismo, o seu funcionamento e mecanismos de atrito. Além disto fez-se também uma breve pesquisa sobre os efeitos da absorção de água na fibra de carbono. Para o dimensionamento do sistema de medição procuraram-se resultados de trabalhos similares de forma a aferir as grandezas a medir e a sensibilidade necessária. O protótipo deve medir a potência conduzida à transmissão para esta rodar em vazio a uma velocidade constante que foi fixada neste caso em 60 rpm, sendo que quanto mais baixa a potencia medida menor o atrito da transmissão. O sensor usado é uma roseta colada a +45 e -45 graus no veio que fornece movimento ao sistema. O sinal é retirado do veio em rotação através de um sistema de anéis deslizantes em bronze onde se usaram escovas de grafite e de filamentos de cobre. Após a construção do protótipo fez-se a calibração estática dos sistemas de medição com bons resultados de sensibilidade e repetibilidade. Estes resultados empíricos também foram comparados com os resultados teóricos não tendo havido discrepâncias relevantes, provando a qualidade das medições de binário obtidas pelos extensómetros. No entanto, devido ao ruído introduzido no sinal pelas escovas em movimento, não foi possível obter resultados de qualidade nos ensaios dinâmicos para a potência e atrito na transmissão em rotação com o presente protótipo. No final apresentam-se sugestões para melhoria em trabalhos futuros.Ever since the beginning of high competition in cycling, that every erffort has been made to improve the results of the athletes. Much of this work is in the development of bicycles and their components. The company Morphis Composites is in the development stage of carbon fiber rear derailleur sprockets. These components made of laminated composite material are exposed to the atmosphere, thus their structural integrity may be affected because it is known that they will absorb water by diffusion and will wear differently from sprockets made of other materials, such as metals. All this can lead to the increase of its friction in the transmission, and it is necessary to create means for the evaluation of this situation. In the present work, the design and construction of a prototype for measuring friction in bicycle transmissions is done. A brief literature review on industrial roller and cycling chains, their operation and friction mechanisms is included. In addition, a brief research was also made on the effects of water absorption on carbon fiber. For the sizing of the measurement system, results of similar work were sought in order to understand the quantities to be measured and the required sensitivity. The prototype shall measure the power delivered to the transmission to idle at a constant speed which has been set at 60 rpm in this case, the lower the measured power the lower the transmission friction. The sensor used is a rosette glued to +45 and -45 degrees in a section of the main shaft before the main sprocket. The signal is drawn from the rotating shaft through a bronze slip ring system where graphite brushes and copper filaments were used. Upon prototype building the static calibration of the measurement systems was made with good results of sensitivity and repeatability. These empirical results were also compared with what would theoretically be expected and there were no relevant discrepancies, proving the quality of the torque measurements obtained by the extensometers. However, due to the noise introduced into the signal by the moving brushes, it was not possible to obtain quality results in the dynamic tests for power and friction in the rotational transmission with the present prototype. At the end, suggestions are presented for improvement in future work.N/

Influence of the length of hospitalisation in post-discharge outcomes in patients with acute heart failure: Results of the LOHRCA study

Objective: To investigate the relationship between length of hospitalisation (LOH) and post-discharge outcomes in acute heart failure (AHF) patients and to ascertain whether there are different patterns according to department of initial hospitalisation. Methods: Consecutive AHF patients hospitalised in 41 Spanish centres were grouped based on the LOH (15 days). Outcomes were defined as 90-day post-discharge all-cause mortality, AHF readmissions, and the combination of both. Hazard ratios (HRs), adjusted by chronic conditions and severity of decompensation, were calculated for groups with LOH >6 days vs. LOH <6 days (reference), and stratified by hospitalisation in cardiology, internal medicine, geriatrics, or short-stay units. Results: We included 8563 patients (mean age: 80 (SD = 10) years, 55.5% women), with a median LOH of 7 days (IQR 4–11): 2934 (34.3%) had a LOH 15 days. The 90-day post-discharge mortality was 11.4%, readmission 32.2%, and combined endpoint 37.4%. Mortality was increased by 36.5% (95%CI = 13.0–64.9) when LOH was 11–15 days, and by 72.0% (95%CI = 42.6–107.5) when >15 days. Conversely, no differences were found in readmission risk, and the combined endpoint only increased 21.6% (95%CI = 8.4–36.4) for LOH >15 days. Stratified analysis by hospitalisation departments rendered similar post-discharge outcomes, with all exhibiting increased mortality for LOH >15 days and no significant increments in readmission risk. Conclusions: Short hospitalisations are not associated with worse outcomes. While post-discharge readmissions are not affected by LOH, mortality risk increases as the LOH lengthens. These findings were similar across hospitalisation departments

Virtual Ontogeny of Cortical Growth Preceding Mental Illness

Background: Morphology of the human cerebral cortex differs across psychiatric disorders, with neurobiology and developmental origins mostly undetermined. Deviations in the tangential growth of the cerebral cortex during pre/perinatal periods may be reflected in individual variations in cortical surface area later in life. Methods: Interregional profiles of group differences in surface area between cases and controls were generated using T1-weighted magnetic resonance imaging from 27,359 individuals including those with attention-deficit/hyperactivity disorder, autism spectrum disorder, bipolar disorder, major depressive disorder, schizophrenia, and high general psychopathology (through the Child Behavior Checklist). Similarity of interregional profiles of group differences in surface area and prenatal cell-specific gene expression was assessed. Results: Across the 11 cortical regions, group differences in cortical area for attention-deficit/hyperactivity disorder, schizophrenia, and Child Behavior Checklist were dominant in multimodal association cortices. The same interregional profiles were also associated with interregional profiles of (prenatal) gene expression specific to proliferative cells, namely radial glia and intermediate progenitor cells (greater expression, larger difference), as well as differentiated cells, namely excitatory neurons and endothelial and mural cells (greater expression, smaller difference). Finally, these cell types were implicated in known pre/perinatal risk factors for psychosis. Genes coexpressed with radial glia were enriched with genes implicated in congenital abnormalities, birth weight, hypoxia, and starvation. Genes coexpressed with endothelial and mural genes were enriched with genes associated with maternal hypertension and preterm birth. Conclusions: Our findings support a neurodevelopmental model of vulnerability to mental illness whereby prenatal risk factors acting through cell-specific processes lead to deviations from typical brain development during pregnancy

Global maps of soil temperature.

Research in global change ecology relies heavily on global climatic grids derived from estimates of air temperature in open areas at around 2 m above the ground. These climatic grids do not reflect conditions below vegetation canopies and near the ground surface, where critical ecosystem functions occur and most terrestrial species reside. Here, we provide global maps of soil temperature and bioclimatic variables at a 1-km &lt;sup&gt;2&lt;/sup&gt; resolution for 0-5 and 5-15 cm soil depth. These maps were created by calculating the difference (i.e. offset) between in situ soil temperature measurements, based on time series from over 1200 1-km &lt;sup&gt;2&lt;/sup&gt; pixels (summarized from 8519 unique temperature sensors) across all the world's major terrestrial biomes, and coarse-grained air temperature estimates from ERA5-Land (an atmospheric reanalysis by the European Centre for Medium-Range Weather Forecasts). We show that mean annual soil temperature differs markedly from the corresponding gridded air temperature, by up to 10°C (mean = 3.0 ± 2.1°C), with substantial variation across biomes and seasons. Over the year, soils in cold and/or dry biomes are substantially warmer (+3.6 ± 2.3°C) than gridded air temperature, whereas soils in warm and humid environments are on average slightly cooler (-0.7 ± 2.3°C). The observed substantial and biome-specific offsets emphasize that the projected impacts of climate and climate change on near-surface biodiversity and ecosystem functioning are inaccurately assessed when air rather than soil temperature is used, especially in cold environments. The global soil-related bioclimatic variables provided here are an important step forward for any application in ecology and related disciplines. Nevertheless, we highlight the need to fill remaining geographic gaps by collecting more in situ measurements of microclimate conditions to further enhance the spatiotemporal resolution of global soil temperature products for ecological applications

Subcortical volumes across the lifespan: data from 18,605 healthy individuals aged 3-90 years

Age has a major effect on brain volume. However, the normative studies available are constrained by small sample sizes, restricted age coverage and significant methodological variability. These limitations introduce inconsistencies and may obscure or distort the lifespan trajectories of brain morphometry. In response, we capitalized on the resources of the Enhancing Neuroimaging Genetics through Meta-Analysis (ENIGMA) Consortium to examine age-related trajectories inferred from cross-sectional measures of the ventricles, the basal ganglia (caudate, putamen, pallidum, and nucleus accumbens), the thalamus, hippocampus and amygdala using magnetic resonance imaging data obtained from 18,605 individuals aged 3-90 years. All subcortical structure volumes were at their maximum value early in life. The volume of the basal ganglia showed a monotonic negative association with age thereafter; there was no significant association between age and the volumes of the thalamus, amygdala and the hippocampus (with some degree of decline in thalamus) until the sixth decade of life after which they also showed a steep negative association with age. The lateral ventricles showed continuous enlargement throughout the lifespan. Age was positively associated with inter-individual variability in the hippocampus and amygdala and the lateral ventricles. These results were robust to potential confounders and could be used to examine the functional significance of deviations from typical age-related morphometric patterns.Education and Child Studie