4,783 research outputs found

    Physical mechanisms of interface-mediated intervalley coupling in Si

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    The conduction band degeneracy in Si is detrimental to quantum computing based on spin qubits, for which a nondegenerate ground orbital state is desirable. This degeneracy is lifted at an interface with an insulator as the spatially abrupt change in the conduction band minimum leads to intervalley scattering. We present a theoretical study of the interface-induced valley splitting in Si that provides simple criteria for optimal fabrication parameters to maximize this splitting. Our work emphasizes the relevance of different interface-related properties to the valley splitting.Comment: 4 pages, revised versio

    Carcinoma da Tiróide em Crianças e Jovens Adultos: Revisão Retrospectiva de 19 Casos

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    Introduction: Thyroid carcinoma is rare in children and young adults. Most of management guidelines are based in data from adult population. Several controversies remain regarding the aggressiveness of clinical presentation and therapeutic approach. Objective: To evaluate all differentiated thyroid carcinoma patients with less than 20 years-old at presentation reflecting the experience of our unit in relation to diagnosis, treatment and follow-up of this clinical entity. Material and Methods: This is a retrospective review of clinical records of all children and young adults followed at Oncology Consultation of Department of Endocrinology of Centro Hospitalar e Universitário de Coimbra between 1996 and 2012. Results: Nineteen patients with mean age of 16 years old were followed, 13 girls and 6 boys. None of the patients had previous neck irradiation. A palpable cervical mass was the presenting complaint in 84.6%. FNA was performed in 15 patients and was diagnostic or suspicious of malignancy in 71.4%. Total thyroidectomy was performed in 18 cases (94.7%). Papillary carcinoma was identified in all. Vascular invasion and multicentry occurred in 21.1%. Mean tumor size was 2.5cm. Cervical lymph node involvement was diagnosed in 31.6% and distant metastases in 5.2%. The majority of patients (18 in 19) were classified as stage I disease. All patients received thyroxine suppressive therapy and postoperative radioiodine ablation was given to 84.2% (mean dose 85.7mCi). During mean follow-up of almost 6 years, 16 patients remain disease free. Conclusion: In our series, cervical lymph node and distant metastases rates were similar to that found in adult population. Overall prognosis was very good

    Análise da acurácia das simulações do modelo BRAMS na Amazônia Ocidental.

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    O objetivo deste estudo é avaliar o modelo de previsão numérica do tempo BRAMS (Brazilian Regional Atmospheric Modelling System), a partir da comparação entre os valores preditos e os observados (dados do NCEP (National Center Environmental Prediction). Foram realizadas comparações entre os valores preditos e os observados através da raiz do erro quadrático médio (RMSE) para os prognósticos de precipitação de 24, 48, 72 e 96 hs, no período de novembro de 2008 a março de 2009. Os resultados mostraram que o modelo BRAMS teve uma performance melhor quando assimilado com dados do modelo global do NCEP

    Aluminization of Scintillating Fibers for the Luminosity Detector of ATLAS

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    We report on tests on 25 cm long squared, 5mmx5mm SCF-3HF optical scintillating fibers, which have been aluminized by the magnetron sputtering technique in Lisbon during 2005. Two groups of fibers were used: 9 isolated fibers (Set I) and 20 stacked inside an acrylic piece (Set II). Fibers in Set I were used to measure the attenuation length of the fibers and were processed in Lisbon but not aluminized. Fibers in Set II were polished in a milling machine with a diamond blade and aluminium coated at one end. The other end was polished at CERN. From this set 10 were cut and polished at 90º with the axis of the fiber and the other 10 the end to be aluminized has been cut at 45º. The reflectivity of the aluminium mirror has been measured in a dedicated test bench. Preliminary results give a value of reflectivity of 51% for the fibers with a 90º cut

    Detecting anomalous energy consumption in android applications

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    The use of powerful mobile devices, like smartphones, tablets and laptops, are changing the way programmers develop software. While in the past the primary goal to optimize software was the run time optimization, nowadays there is a growing awareness of the need to reduce energy consumption. This paper presents a technique and a tool to detect anomalous energy consumption in Android applications, and to relate it directly with the source code of the application. We propose a dynamically calibrated model for energy consumption for the Android ecosystem, and that supports different devices. The model is then used as an API to monitor the application execution: first, we instrument the application source code so that we can relate energy consumption to the application source code; second, we use a statistical approach, based on fault-localization techniques, to localize abnormal energy consumption in the source code

    High pressure effects on the activities of cathepsins B and D of mackerel and horse mackerel muscle

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    6 páginas, 4 figurasWe determined high pressure processing (HPP) effects on the activities of cathepsins B and D in the muscles of mackerel (Scomber scombrus) and horse mackerel (Trachurus trachurus). In mackerel, the cathepsin B activity decrease reached 40% at 450 MPa while in horse mackerel, low and intermediate pressures (150 and 300 MPa) caused an activity increase (30%) but at 450 MPa a decrease of up to 60%. In both species, cathepsin D activity increased after a 300 MPa treatment (up to 2-fold for mackerel and 60% for horse mackerel) and decreased on a 450 MPa treatment. The activity increase is probably due to HPP damage of lysosome releasing enzymes into the fish muscle. Based on the HPP effects on the activities of cathepsins B and D, 450 MPa may be used to reduce the proteolytic activity of cathepsin B prior to chilled or frozen storage of these fish speciesSupported by the Xunta de Galicia, Spain Project 10TAL402001PR, 2010-2012, and FCT (Portugal), European Union, QREN, FEDER and COMPETE thorough QOPNA research unit, Project PEst-C/QUI/UI0062/2013; FCOMP-01-0124-FEDER-037296. Also supported by he USDA National Institute of Food and Agriculture, Grants No. 2011-31200-06041 and 2012-31200-06041Peer reviewe

    Twin twin transfusion and fetomaternal transfusion

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    Introdução: Os autores descrevem um caso de transfusão feto materna (TFM) significativa com repercussão fetal, após ablação de anastomoses vasculares placentares, por síndrome de transfusão feto fetal (STFF). Caso Clínico:31 anos, saudável, primigesta, gravidez espontânea gemelar, monocoriónica biamniótica. A ecografia do 1º trimestre, efetuada às 12 semanas, mostrava concordância dos valores do comprimento crânio caudal (CCC), mas discordância dos valores da medida da translucência da nuca (TN). O rastreio combinado do 1º trimestre foi negativo. Às 16 semanas foi diagnosticado um STFF – estadio II/III de Quintero. A amniocentese revelou um cariótipo normal 46, XY no feto dador e um cariótipo anormal 47, XYY no feto receptor. Às 17 semanas foi efetuada ablação laser das anastomoses vasculares placentares, tendo ocorrido a morte do feto dador às 18 semanas. Às 22 semanas foi diagnosticada anemia fetal, por TFM, confirmada por citometria de fluxo. Às 26 semanas foi constatada dilatação de ansa intestinal - suspeita de atrésia intestinal. Parto por cesariana às 37 semanas. RN: sexo masculino, 2660g, Índice de Apgar 5/8/10. Confirmada atrésia ileal tipo II e efetuada enterectomia segmentar. Evolução clínica favorável. Conclusão: Trata-se de um caso de transfusão feto-fetal seguido de transfusão feto-materna, com atrésia intestinal em provável relação com anemia fetal, em feto com cromossomopati

    Peripheral Attentional Targets under Covert Attention Lead to Paradoxically Enhanced Alpha Desynchronization in Neurofibromatosis Type 1

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    The limited capacity of the human brain to process the full extent of visual information reaching the visual cortex requires the recruitment of mechanisms of information selection through attention. Neurofibromatosis type-1 (NF1) is a neurodevelopmental disease often exhibiting attentional deficits and learning disabilities, and is considered to model similar impairments common in other neurodevelopmental disorders such as autism. In a previous study, we found that patients with NF1 are more prone to miss targets under overt attention conditions. This finding was interpreted as a result of increased occipito-parietal alpha oscillations. In the present study, we used electroencephalography (EEG) to study alpha power modulations and the performance of patients with NF1 in a covert attention task. Covert attention was required in order to perceive changes (target offset) of a peripherally presented stimulus. Interestingly, alpha oscillations were found to undergo greater desynchronization under this task in the NF1 group compared with control subjects. A similar pattern of desynchronization was found for beta frequencies while no changes in gamma oscillations could be identified. These results are consistent with the notion that different attentional states and task demands generate different patterns of abnormal modulation of alpha oscillatory processes in NF1. Under covert attention conditions and while target offset was reported with relatively high accuracy (over 90% correct responses), excessive desynchronization was found. These findings suggest an abnormal modulation of oscillatory activity and attentional processes in NF1. Given the known role of alpha in modulating attention, we suggest that alpha patterns can show both abnormal increases and decreases that are task and performance dependent, in a way that enhanced alpha desynchronization may reflect a compensatory mechanism to keep performance at normal levels. These results suggest that dysregulation of alpha oscillations may occur in NF1 both in terms of excessive or diminished activation patterns
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