2,487 research outputs found

    Rolling/Slipping Motion of Euler's Disk

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    We present an experimental study of the motion of a circular disk spun onto a table. With the help of a high speed video system, the temporal evolutions of (i) the inclination angle α\alpha, (ii) the angular velocity ω\omega and (iii) the precession rate Ω\Omega are studied. The influence of the mass of the disk and the friction between the disk and the supporting surface are considered. %The motions of disks with different masses and over different surfaces are studied. The inclination angle α\alpha and the angular velocity are observed to decrease according to a power law. We also show that the precession rate Ω\Omega diverges as the disk stops. Exponents are measured very near the collapse as well as on long range times. Collapsing times have been also measured. The results are compared with previous theoretical and experimental works. The major source of energy dissipation is found to be the slipping of the disk on the plane.Comment: Submitted for publication (2003) - 6page

    Emergence of supersymmetry on the surface of three dimensional topological insulators

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    We propose two possible experimental realizations of a 2+1 dimensional spacetime supersymmetry at a quantum critical point on the surface of three dimensional topological insulators. The quantum critical point between the semi-metallic state with one Dirac fermion and the s-wave superconducting state on the surface is described by a supersymmetric conformal field theory within ϵ\epsilon-expansion. We predict the exact voltage dependence of the differential conductance at the supersymmetric critical point.Comment: 8 pages, 2 figures; published versio

    MASS TRANSFER CORRELATION FOR THE REMOVAL OF COPPER IONS FROM WASTEWATER

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    One of the biggest problems with ore processing in extractive metallurgical industries is the high toxicity of the heavy metals waste content (e.g., copper, lead, nickel and chrome). This work investigates the copper (II) íons removal from aqueous solutions in concentrations up to 1000 ppm. Therefore, a fluidized bed electrolytic reactor was used with flow-by configuration considered as a hopeful method due to the large specific surface area and the high mass transfer rate. The performance of the electrochemical reactor was investigated by using different porosities. Dimensionless Sherwood and Reynolds numbers were correlated to characterize the mass transport properties of the reactor, and they were fitted to the equation Sh = a.Reb.Sc1/3

    Low Dose Thalidomide for Treatment of Resistant Discoid Lupus Erythematosus. A Case Report

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    Discoid lupus erythematosus (DLE) is a chronic, indolent, disfiguring disease that is characterized by scaly, erythematous, disk-shaped patches and plaques followed by atrophy, scarring and depigmentation. In a small number of patients, it is refractory to standard therapies. In several studies, thalidomide has been reported to be an effective treatment in those cases. The most fearful side effects are teratogenicity and neuropathy. Adequate counseling and vigilance must be given to the patients. We report a 45-year-old Portuguese woman who presented with a 20-year history of severe facial and scalp DLE confirmed by histopathology. For several years, it failed to respond to several therapies, including topical, intralesional and oral corticosteroids, hydroxychloroquine, methotrexate, azathioprine and topical tacrolimus. Thalidomide was initiated at a dosage of 50mg/day and the skin lesions had improved dramatically after three weeks with complete clinical remission. Two months later, the dose was reduced to 50mg, five days per week without disease rebound. The patient´s concomitant medications during the treatment included sunscreen, hydroxycholoroquine, enoxaparin and aspirin to prevent thromboembolic events. Pregnancy testing, routine laboratory and electrocardiography were performed at regular intervals for safety monitoring and the results were within normal limits. Only minor side effects as nausea, constipation and somnolence were noted, however, they improved with dose reduction. Our data confirm that thalidomide therapy is an alternative or adjunctive treatment for patients with severe, chronic DLE that is refractory to standard therapies. In this patient, low-dose thalidomide was an effective treatment with minimal side effects

    Human Mobility in Large Cities as a Proxy for Crime

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    We investigate at the subscale of the neighborhoods of a highly populated city the incidence of property crimes in terms of both the resident and the floating population. Our results show that a relevant allometric relation could only be observed between property crimes and floating population. More precisely, the evidence of a superlinear behavior indicates that a disproportional number of property crimes occurs in regions where an increased flow of people takes place in the city. For comparison, we also found that the number of crimes of peace disturbance only correlates well, and in a superlinear fashion too, with the resident population. Our study raises the interesting possibility that the superlinearity observed in previous studies [Bettencourt et al., Proc. Natl. Acad. Sci. USA 104, 7301 (2007) and Melo et al., Sci. Rep. 4, 6239 (2014)] for homicides versus population at the city scale could have its origin in the fact that the floating population, and not the resident one, should be taken as the relevant variable determining the intrinsic microdynamical behavior of the system.Comment: 17 pages, 8 Figure

    Produção escrita : o processamento de informação medidado pelo estilo cognitivo e pelo nível de inteligência

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    O padrão estilístico Dependência-Independência de Campo (DIC) tem sido relacionado com diversos aspectos da personalidade, procedimentos e estratégias utilizadas na resolução de problemas ou ponderado numa agregação de aspectos cognitivos, afectivos e motivacionais, inerentes ao processamento da informação e resolução de problemas. Apesar da subsistência da comedida investigação nesta conjectura, formulada por Witkin, os resultados perduram inconclusivos e pouco consensuais. Neste estudo, relacionou-se a DIC com a Expressão Escrita das crianças, área reveladora de grandes dificuldades no processamento de informação e justificando uma maior atenção de pais e educadores. Esta dificuldade ocorre nos processos de planificação, de tradução e de revisão do texto escrito, que explicam toda a complexidade dos procedimentos na produção de um texto. Participaram neste estudo 92 alunos do 3º e o 4º ano de escolaridade [45 rapazes e 47 meninas], com idades compreendidas entre os 8 e os 11 anos, e a frequentarem escolas públicas da cidade de Braga. Para avaliação do estilo cognitivo (DIC) utilizamos o teste Children’s Embedded Figures Test (CEFT) e para a avaliação da inteligência recorreu-se à prova Matrizes Coloridas Progressivas de Raven. Os resultados deste estudo permitem afirmar uma associação significativa do Estilo Cognitivo (DIC) com a Expressão Escrita das crianças favorecendo os alunos independentes de campo.Faculdade de Psicologia - Universidade de LisboaSociedade Portuguesa de PsicologiaCGD - Caixa Geral de DepósitosCEGOCSHLPSE - Produtos e Serviços de Estatística, Lda.ProfiForm

    Generation of a human iPS cell line from a patient with retinitis pigmentosa due to EYS mutation

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    Retinitis pigmentosa (RP) is an inherited retinal degenerative disease. Mutations in EYS have been associated with autosomal recessive RP. The human iPS cell line, CABi002-A, derived from peripheral blood mononuclear cells from a patient carrying a heterozygous double mutation in EYS gene was generated by non-integrative reprogramming technology, using hOCT3/4, hSOX2, hc-MYC and hKLF4 reprogramming factors. Pluripotency and differentiation capacity were assessed by immunocytochemistry and RT-PCR. This iPSC line can be further differentiated towards the affected cells to understand the pathophysiology of the disease and test new therapeutic strategies.Cellex FoundationFundación Progreso y Salu

    Late Bronze Age metallic depositions in the AssureiraValley. The case study of Moinhos de Golas site (Solveira, Montalegre, Northern Portugal)

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    [PT] Este trabalho tem como objetivo dar a conhecer um conjunto de achados metálicos do Bronze Final, em associação com fragmentos cerâmicos e líticos, encontrados no sítio de Moinhos de Golas, freguesia de Solveira, concelho de Montalegre. A coleção metálica é composta por armas, artefactos de adorno, utensílios, possíveis elementos de produção metalúrgica, entre outros objetos de difícil classificação. As análises de composição química a peças selecionadas, embora preliminares, mostram que a maioria dos artefactos foram produzidos numa liga de bronze binário (Cu-Sn). Pelo facto de terem sido encontradas dispersas por vários lugares do outeiro, este grupo de peças não pode considerar-se um depósito fechado.[EN] This work aims to publish a set of metal findings attributed to Bronze Age, and found in association with ceramic and lithic fragments. These were found in the Moinhos de Golas site, Solveira parish, in the Montalegre council. This set consists of metallic weapons, ornaments, tools, and some objects that might be related to metallurgical processes, among other objects difficult to classify. Preliminary elemental analysis made on selected artefacts point out that most objects were produced in a binary bronze alloy. This set of artefacts, given their finding circumstances, should not be regarded as a closed hoard.Este trabalho foi desenvolvido no âmbito dos projetos Metalurgia Primitiva no Território Português–EARLYME-TAL(PTDC/HIST-ARQ/110442/2008) e Espaços Naturais, Arquiteturas, Arte rupestre e Deposições na Pré-história Recente da Fachada Ocidental do Centro e Norte Português: das Ações aos Significados - ENARDAS (PTDC/HIS-ARQ/112983/2009), financiado pelo Programa Operacional Temático Factores de Competitividade (COMPETE) e comparticipados pelo Fundo Comunitário Europeu FEDER. Os autores agradecem à Fundação para a Ciência e a Tecnologia (FCT) as bolsas individuais (SFRH/BD/65143/2009) e (SFRH/BPD/73245/2010) concedidas a João Fonte e Elin Figueiredo, respetivamente, e o apoio financeiro concedido ao CENIMAT/I3N através do Projecto Estratégico LA25/2013-2014 (PEst-C/CTM/LA0025/2011).Peer Reviewe
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