28,907 research outputs found

    Water and sediments geochemistry and elemental fluxes on a Large Dam: case study of Ridracoli reservoir.

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    Since the study of Large Dam Reservoirs is of worldwide interest, in this PhD project we investigated the Ridracoli reservoir, one of the main water supply in Emilia-Romagna (north-eastern Italy). This work aims to characterize waters and sediments to better understand their composition, interactions and any process that occurs, for a better geochemical and environmental knowledge of the area. Physical and chemical analyses on the water column have shown an alternation of stratification and mixing of water in the reservoir’s water body due to seasonal variations in temperature and density. In particular, it was observed the establishment, in late summer, of anoxic conditions at the bottom, which in turn affects the concentration and mobility of some elements of concern (e.g. Fe and Mn) for the water quality. Sediments within the reservoir and from surrounding areas were analysed for organic matter, total inorganic composition and grain size, assessing the inter-element relationship, grain size, geological background and damming influences on their chemistry, through descriptive statistics, Principal Component Analysis and Cluster Analysis. The reservoir’s area was also investigated by pseudo total composition (Aqua Regia digestion), degree of elements extractability, and enrichment factors, then analysed and compared to limits by law and literature. Sediment cores, interstitial waters, and benthic chamber data from the bottom were of great interest due to organic matter degradation, early diagenesis, mineral formation at water-sediment interface and observed flows. Finally, leaching test and extraction procedures, of environmental interest, showed peculiar partitioning, both regarding spatial and in-depth distribution, and the absence of pollution. Collectively, our results are useful for the comprehension of processes that occur in water and sediments of Ridracoli reservoir, providing important knowledges on the site that could be relevant for the management of the resource and the planning of future interventions

    The structure of incipient coastal counter currents in South Portugal as indicator of their forcing agents

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    The alongshore subtidal water circulation along the South Portugal inner shelf is characterized by the temporal alternation of equatorward (i.e., broadly eastward) flows related to coastal upwelling processes and poleward (i.e., broadly westward) Coastal Counter Currents (CCCs). The objective of this study is to get insights about the main drivers of CCCs based on kinematic parameters describing the structure of the flow at the moment it changes direction. The parameters are derived from an extensive bottom-mounted ADCP dataset (16 deployments; 34,121 hourly records) collected at a single mooring (23 m water depth). Results show that the so-called incipient flows present contrasted general patterns whether they turn from equatorward to poleward or the opposite. Complementary observations at a nearby station indicate that these characteristics are spatially consistent along the studied area. Although 70% of CCCs are generated under favourable wind conditions (Levanter), these flows generally develop through the bed layer, in particular in summer. Hence, the Levanter wind - expected to promote flow setup through the surface layer - is not the main driver of CCCs in most cases. The general structure of incipient CCCs strongly suggests that the dominant force competing with the wind stress is an alongshore pressure gradient (APG). Furthermore, the maximum equatorward flow magnitude before CCCs setup is significantly correlated with the following (poleward) acceleration of incipient CCCs near the bed. Such relation is consistent with the development of CCCs due to the unbalance of an APG (produced during active upwelling) when wind relaxes. This process is further supported by an analysis of the depth-averaged momentum equation which suggests that the coastal circulation is mainly driven by linear dynamics in the region.IF/00661/2014/CP1234, SFRH/BD/140250/ 2018, UID/Multi/04326/2019info:eu-repo/semantics/publishedVersio

    Targeting hypothalamus: diet impact, bacterial composition and memory impair

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    Cholesterol metabolism is critical for neuronal functions such as, myelin formation, neurotransmitters release, membrane repair and also synaptogenesis, in the Central Nervous System (CNS), and its homeostasis is mainly maintained by CYPX. This enzyme catalyses the conversion of cholesterol into X-Hydroxycholesterol (X-HC) and may be a useful marker of neurodegenerative diseases. The X-HC is able to cross the blood-brain-barrier (BBB) into the circulation, having possible roles in the overall bile acid synthesis in the liver, therefore having an indirect impact on intestinal microbiota within human Gastrointestinal tract (GI). In the other hand, a diet mainly rich in fat, carbohydrates and protein, a typical Western diet, have been highly associated with changes in the GI environment, promoting alterations in intestinal microbiota composition, termed as dysbiosis, being associated with early metabolic physiopathological changes, such as increased intestinal barrier permeability and a state of low-grade intestinal inflammation. The main objective of this study was to determine the effects of either Cyp overexpression and silencing treatment and diet on intestinal bacterial groups, cognitive abilities and also on colon health status. C57BL/J6 mice were fed with either chow diet or an High Fat Diet (HFD), for 12 weeks. To determine the effects caused by both Cyp overexpression and silencing and also by the HFD and Control diet on the intestinal bacteriome, the quantification of several intestinal bacterial groups was performed using qPCR. The targeted bacterial groups included Bacteroidetes, Firmicutes, Sulphate-Reducing Bacteria (SRB), Betaproteobacteria, Delta-and Gammaproteobacteria, Actinobacteria and Tenericutes. The exposure of mice to an HFD resulted in variations in the loads of the intestinal bacteria. Interestingly, the Cyp silencing lead to an approximation of intestinal bacterial loads between mice exposed to the different diets. The Cyp silencing resulted in a decreased performance in Y-maze spontaneous alternation test, within subjects with a chow diet. In addition, both Cyp overexpression and silencing in mice exposed to an HFD showed increased signs of intestinal inflammation. Taken together, this study showed that intestinal microbiota is mainly influenced by dietary factors.Numa zona central do cérebro humano encontra-se o hipotálamo, sendo este constituído por quatros divisões principais, a área pré-ótica, hipotálamo anterior, hipotálamo tuberal e hipotálamo posterior. Sendo cada uma destas divisões constituída por diversos núcleos, desempenhando funções fundamentais para a manutenção da homeostasia do nosso organismo, tais como, termorregulação, controlo sobre o metabolismo energético, controlo sobre os estados de sono, respostas ao stress, crescimento, e também exerce o controlo sobre o nosso comportamento social, emocional, cognitivo e reprodutivo. Este pequeno órgão atua como uma central de comunicação entre o sistema nervoso central e a periferia, podendo regular vários órgãos periféricos como, a tiroide, o musculo, o osso e ainda o sistema gastrointestinal. A comunicação entre o sistema nervoso central e a periferia é essencialmente controlada pela barreira hematoencefálica, que para além de controlar a passagem de moléculas em ambos os sentidos, consoante as necessidades do organismo, também controla a entrada de toxinas e agentes patogénicos para o cérebro. Assim sendo, um bom funcionamento da barreira hematoencefálica é essencial tanto para o cérebro, como para os órgãos periféricos e, a sua disfunção, especialmente ao nível das “tight junctions”, resulta num aumento de permeabilidade da barreira, aumento de infiltração de células inflamatórias e ainda uma desregulação dos processos de transporte de nutrientes para ambos os sistemas, sendo estes eventos cada vez mais associados ao desenvolvimento de doenças neurodegenerativas, como também doenças ao nível metabólico, como por exemplo, a doença de Alzheimer ou Diabetes. O cérebro é o órgão mais rico em colesterol do corpo humano, contendo cerca de 23% do colesterol total existente no organismo, e ao contrário da zona periférica em que a homeostasia de colesterol é essencialmente dependente da dieta, a homeostasia de colesterol no cérebro parece ser maioritariamente realizada através de síntese de novo e reciclagem deste, a partir de acetilcoenzima A em astrócitos. Depois da sua síntese, o colesterol é conduzido até aos neurónios onde irá desempenhar funções a nível da formação de mielina, reparação da membrana, e ainda sinaptogênese. Diversos estudos têm sugerido que a acumulação de colesterol nos neurónios está associada a uma disfunção a nível cognitivo, sendo assim, este esterol tem sido associado a doenças neurodegenerativas, como a doença de Huntington ou a doença de Alzheimer. No entanto, apesar da sua importância, este composto não consegue atravessar a barreira hematoencefálica. Dentro da superfamília Citocromo P450, mais propriamente a proteína CYPx, está envolvida no metabolismo de colesterol no cérebro, e a sua ação reside na sua capacidade de converter colesterol a oxisterol, ao introduzir um oxigénio na cadeia altamente hidrofóbica do colesterol, sendo fulcral para a sua translocação através da barreira hematoencefálica. Foram reportadas evidências em que cerca de 90% do oxisterol resultante da ação de CYPx (X-HC), atravessa a barreira hematoencefálica para a circulação, onde será conduzido essencialmente para o fígado, onde é utilizado para a síntese de ácidos biliares. Atualmente, são sugeridas duas vias principais para síntese de ácidos biliares no fígado, a via Clássica e a via Alternativa. Resumidamente, a via clássica envolve a hidroxilação do colesterol catalisado pela enzima CYP7A1, contribuindo com cerca de 75% da síntese total de ácidos biliares, enquanto que a via alternativa é catalisada pela ação das enzimas CYP27A1 e CYP7B1, sendo posteriormente conjugados com glicina ou taurina, e armazenados na vesicula biliar. A formação de estruturas micelares por parte dos ácidos biliares, deve-se às suas características anfipáticas, o que facilita a emulsificação, absorção e digestão de lípidos e vitaminas insolúveis. Porém, os ácidos biliares secundários, metabolitos resultantes da atividade microbiana podem ser altamente tóxicos para o organismo, e os seus efeitos têm sido associados a doenças como o cancro do colon e reto. No intestino humano existe uma vasta e complexa comunidade de microrganismos, denominado de “Microbiota Intestinal”. Mantendo uma relação de simbiose, a microbiota intestinal confere diversas vantagens ao hospedeiro, nomeadamente a nível de maturação do sistema imune, proteção contra agentes patogénicos, manutenção da permeabilidade da barreira gastrointestinal, fermentação e absorção de carboidratos e, portanto, manter uma microbiota equilibrada, em eubiose, assegura uma boa função não só digestiva, como também a nível cerebral. Existem várias evidências que mostram uma comunicação bidirecional entre a microbiota gastrointestinal e cérebro, denominado de “microbiota-gut-brain axis”, assim sendo, a atividade da microbiota intestinal pode influenciar o nosso cérebro, e vice-versa. A via de comunicação entre estes sistemas ainda não está completamente compreendida, no entanto pensa-se que seja feita através do nervo Vago, Sistema Entérico nervoso e ainda através de metabolitos bacterianos. De entre todos os fatores que influenciam a microbiota intestinal, a dieta, é o fator que mais se destaca devido ao seu efeito notável. De facto, diversas publicações evidenciam um efeito negativo por parte de uma alimentação rica em gorduras, nomeadamente pela redução da diversidade microbiana no nosso intestino e ainda um aumento da permeabilidade da barreira gastrointestinal, possibilitando a passagem de endotoxinas e outros metabolitos bacterianos para a circulação, levando a um estado de inflamação intestinal de baixo grau. Para além disso, existem evidências que mostram que uma alimentação rica em gorduras pode levar a uma disfunção a nível cognitivo, e ainda a uma desregulação do metabolismo de ácidos biliares, caracterizado pelo aumento dos níveis que ácidos biliares em circulação, podendo ter efeitos a nível da microbiota intestinal. Este trabalho teve como principal objetivo analisar o efeito da sobre-expressão e silenciamento do gene Cyp, e de dois tipos de dieta, uma dieta controlo e uma dieta rica em gordura, na microbiota intestinal de ratinhos. Para além disso, os seus efeitos também foram analisados a nível cognitivo, bem como na inflamação intestinal. Foram selecionados 70 ratinhos da espécie C57BL/J6 que foram divididos em dois grupos. O primeiro grupo foi destinado à sobre-expressão deste gene, enquanto que o segundo grupo foi destinado ao estudo do silenciamento deste. As duas populações de ratinhos foram alimentadas com uma dieta controlo e uma dieta rica em gordura por 12 semanas. A intervenção a nível do hipotálamo (Cyp) teve lugar após as primeiras quatro semanas. A análise da composição da microbiota intestinal foi realizada a partir de amostras fecais, através de qPCR utilizando primers direcionados para diferentes grupos bacterianos, nomeadamente Bacteroidetes, Firmicutes, Bactérias Sulfato-Redutoras (BSR), Betaproteobacteria, Delta-e Gammaproteobacteria, Actinobacteria e Tenericutes. Através dos resultados obtidos da análise da composição da microbiota intestinal, no ensaio da sobre- expressão foi possível distinguir a microbiota intestinal de indivíduos que foram sujeitos a uma dieta controlo, daqueles que foram sujeitos a uma dieta rica em gorduras, o que indica que as suas variações se deveram maioritariamente ao tipo dieta a que foram sujeitos. No entanto, o silenciamento deste gene também mostrou exercer influência, levando a uma aproximação em termos da microbiota intestinal, entre indivíduos com diferentes dietas. A análise a nível cognitivo, utilizando o teste Y-Maze spontaneous alternations, indicou que contrariamente a estudos anteriores, uma alimentação rica em gorduras não afetou a memória a curto prazo dos ratinhos, no entanto, o silenciamento deste gene levou a uma diminuição da memória a curto prazo, em comparação com os ratinhos sujeitos à sobre-expressão. Por último, através da análise de cortes histológicos do intestino, foi possível verificar que, uma desregulação do metabolismo de colesterol no cérebro, bem como uma alimentação rica em gorduras, levou a uma maior ocorrência de inflamação intestinal

    Grasping nothing: a study of minimal ontologies and the sense of music

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    If music were to have a proper sense – one in which it is truly given – one might reasonably place this in sound and aurality. I contend, however, that no such sense exists; rather, the sense of music takes place, and it does so with the impossible. To this end, this thesis – which is a work of philosophy and music – advances an ontology of the impossible (i.e., it thinks the being of what, properly speaking, can have no being) and considers its implications for music, articulating how ontological aporias – of the event, of thinking the absolute, and of sovereignty’s dismemberment – imply senses of music that are anterior to sound. John Cage’s Silent Prayer, a nonwork he never composed, compels a rerethinking of silence on the basis of its contradictory status of existence; Florian Hecker et al.’s Speculative Solution offers a basis for thinking absolute music anew to the precise extent that it is a discourse of meaninglessness; and Manfred Werder’s [yearn] pieces exhibit exemplarily that music’s sense depends on the possibility of its counterfeiting. Inso-much as these accounts produce musical senses that take the place of sound, they are also understood to be performances of these pieces. Here, then, thought is music’s organon and its instrument

    Preclinical trials in Alzheimer's disease: Sample size and effect size for behavioural and neuropathological outcomes in 5xFAD mice.

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    5xFAD transgenic (TG) mice are used widely in AD preclinical trials; however, data on sample sizes are largely unaddressed. We therefore performed estimates of sample sizes and effect sizes for typical behavioural and neuropathological outcome measures in TG 5xFAD mice, based upon data from single-sex (female) groups. Group-size estimates to detect normalisation of TG body weight to WT littermate levels at 5.5m of age were N = 9-15 depending upon algorithm. However, by 1 year of age, group sizes were small (N = 1 -<6), likely reflecting the large difference between genotypes at this age. To detect normalisation of TG open-field hyperactivity to WT levels at 13-14m, group sizes were also small (N = 6-8). Cued learning in the Morris water maze (MWM) was normal in Young TG mice (5m of age). Mild deficits were noted during MWM spatial learning and memory. MWM reversal learning and memory revealed greater impairment, and groups of up to 22 TG mice were estimated to detect normalisation to WT performance. In contrast, Aged TG mice (tested between 13 and 14m) failed to complete the visual learning (non-spatial) phase of MWM learning, likely due to a failure to recognise the platform as an escape. Estimates of group size to detect normalisation of this severe impairment were small (N = 6-9, depending upon algorithm). Other cognitive tests including spontaneous and forced alternation and novel-object recognition either failed to reveal deficits in TG mice or deficits were negligible. For neuropathological outcomes, plaque load, astrocytosis and microgliosis in frontal cortex and hippocampus were quantified in TG mice aged 2m, 4m and 6m. Sample-size estimates were ≤9 to detect the equivalent of a reduction in plaque load to the level of 2m-old TG mice or the equivalent of normalisation of neuroinflammation outcomes. However, for a smaller effect size of 30%, larger groups of up to 21 mice were estimated. In light of published guidelines on preclinical trial design, these data may be used to provide provisional sample sizes and optimise preclinical trials in 5xFAD TG mice

    Certified high-efficiency "large-area" perovskite solar cells module for Fresnel lens-based concentrated photovoltaic

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    This is the author accepted manuscript. The final version is available on open access from Cell Press via the DOI in this recordData availability: All data generated or analysed during this study are included in the Supplementary Information article and its data source. Source data are provided in this paper. All data reported in this paper will be shared by the lead contact upon request.The future of energy generation is well in tune with the critical needs of the global economy, leading to more green innovations and emissions-abatement technologies. Introducing concentrated photovoltaic (CPV) is one of the most promising technologies owing to its high photo-conversion efficiency (PCE). While most researchers use silicon and cadmium telluride for CPV, we investigate the potential in nascent technologies, such as perovskite solar cell (PSC). This work constitutes a preliminary investigation into a ‘large-area’ PSC module under a Fresnel lens (FL) with a ‘refractive optical concentrator-silicon-on-glass’ base to minimise the PV performance and scalability trade-off concerning the PSCs. The FL-PSC system measured the solar current-voltage characteristics in variable lens-to-cell distances and illuminations. A systematic study of the PSC module temperature was monitored using the COMSOL transient heat transfer mechanism. The FL-based technique for ‘large-area’ PSC architecture is an unfolded technology that further facilitates the potential for commercialisation.Engineering and Physical Sciences Research Council (EPSRC)Valais Energy Demonstrators FundEuropean Union Horizon 2020Deputyship for Research & Innovation, Ministry of Education, Saudi Arabi

    Weather /Climate Manual for Agriculture

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    Agriculture is an economic activity that produce food necessary for human livelihood and it is highly dependent upon weather and climate; however, agriculture is also likely to be very vulnerable to climate variability and change. Climate variability and climate change are the main causes of stress on food production and availability

    Effects of School Shift Change on Sleep and Academic Performance: A Quasi-Experimental Evaluation for Adolescent Students in Brazil

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    This paper investigates the influence of the school shift change on the academic performance of 6th and 7th graders (lower secondary education) of public schools in the city of Recife, Brazil. The empirical analyses use educational data from a panel of the Brazilian Ministry of Education, with a sample of 4,500 students, 3,468 parents or guardians, 85 principals, and 137 teachers working in 87 public schools that were spatially distributed. The identification strategy explores a quasi-experiment in which some classes of the investigated sample had their school shifts changed between the two years, which occurred exclusively due to the school logistics and regardless of the parents’ preferences. Difference-in-differences models combined with propensity score matching demonstrate that students who shifted from morning to afternoon between the two years analyzed improved their Portuguese test scores, and that those who experienced the opposite change, from afternoon to morning, had a drop in the performance. Estimations in intermediary outcomes also reveal that the changes in the students’ sleeping habits are an important mechanism that explains the relation between the scores and the school shift

    Some Aspects of The Political Modernization of Uzbekistan

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    This article reveals the content, purpose of political modernization and its methodological basis in Uzbekistan. The analysis of the main paradigms about political modernization has been carried out. The ways of Uzbekistan in modernization are considered. A brief description of the process of political modernization in Uzbekistan is considered. The studied experience of socio-political thought is necessary to address issues of political modernization in Uzbekistan

    High-Dimensional Private Empirical Risk Minimization by Greedy Coordinate Descent

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    In this paper, we study differentially private empirical risk minimization (DP-ERM). It has been shown that the worst-case utility of DP-ERM reduces polynomially as the dimension increases. This is a major obstacle to privately learning large machine learning models. In high dimension, it is common for some model's parameters to carry more information than others. To exploit this, we propose a differentially private greedy coordinate descent (DP-GCD) algorithm. At each iteration, DP-GCD privately performs a coordinate-wise gradient step along the gradients' (approximately) greatest entry. We show theoretically that DP-GCD can achieve a logarithmic dependence on the dimension for a wide range of problems by naturally exploiting their structural properties (such as quasi-sparse solutions). We illustrate this behavior numerically, both on synthetic and real datasets
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