2,655 research outputs found

    Quantum radiation pressure on a moving mirror at finite temperature

    Get PDF
    We compute the radiation pressure force on a moving mirror, in the nonrelativistic approximation, assuming the field to be at temperature T.T. At high temperature, the force has a dissipative component proportional to the mirror velocity, which results from Doppler shift of the reflected thermal photons. In the case of a scalar field, the force has also a dispersive component associated to a mass correction. In the electromagnetic case, the separate contributions to the mass correction from the two polarizations cancel. We also derive explicit results in the low temperature regime, and present numerical results for the general case. As an application, we compute the dissipation and decoherence rates for a mirror in a harmonic potential well.Comment: Figure 3 replaced, changes mainly in Sections IV and V, new appendix introduced. To appear in Physical Review

    Perioral pigmentation: What is your diagnosis?

    Get PDF
    Pigmented spots in the skin and mucosa (lentigines) can be found in various diseases called familial lentiginosis syndromes; Peutz-Jeghers syndrome (PJS) is one of them. It is characterized by the association of mucocutaneous melanin pigmentation and hamartomatous gastrointestinal polyps. Patients with PJS are at increased risk of intussusception and cancer development (gastrointestinal and non-gastrointestinal tumors). We present a 5-year-old girl with pigmented macules of perioral and perinasal skin, lips, and buccal mucosa and review lentiginoses and the surveillance of PJS

    The Differentiation and Promotion of Students’ Rights in Portugal

    Get PDF
    This investigation includes a differential study (Study 1) and a quasi-experimental research (Study 2). In Study 1, the objective was to establish to what extent students’ rights existed and analyse the differentiation between students’ rights with Portuguese and immigrant mothers, throughout school years. The sample consisted of 537 students with Portuguese and immigrant mothers, distributed by different school years (7th, 9th and 11th grades). The Children’s Rights Scale (Hart et al., 1996; Veiga, 2001) was used. In Study 2, the purpose was to analyse the effects on students’ rights of the use by teachers of a communicational intervention program, supervised by school psychologists. The sample involved 7th and 9th grade students, in a total of four classes, two forming the experimental groups (n = 36) and two the control groups (n = 43); as in Study 1, the Children’s Rights Scale was used. The results indicated the effectiveness of the communicational intervention program on students’ rights and are consistent with previous studies. An implication is that psychologists and teachers, working together and taking a human rights perspective, may develop an important role in projects to promote the students’ rights

    Inertial forces in the Casimir effect with two moving plates

    Full text link
    We combine linear response theory and dimensional regularization in order to derive the dynamical Casimir force in the low frequency regime. We consider two parallel plates moving along the normal direction in DD-dimensional space. We assume the free-space values for the mass of each plate to be known, and obtain finite, separation-dependent mass corrections resulting from the combined effect of the two plates. The global mass correction is proportional to the static Casimir energy, in agreement with Einstein's law of equivalence between mass and energy for stressed rigid bodies.Comment: 9 pages, 1 figure; title and abstract changed; to appear in Physical Review

    Measurement of radioactive contamination in the high-resistivity silicon CCDs of the DAMIC experiment

    Full text link
    We present measurements of radioactive contamination in the high-resistivity silicon charge-coupled devices (CCDs) used by the DAMIC experiment to search for dark matter particles. Novel analysis methods, which exploit the unique spatial resolution of CCDs, were developed to identify α\alpha and β\beta particles. Uranium and thorium contamination in the CCD bulk was measured through α\alpha spectroscopy, with an upper limit on the 238^{238}U (232^{232}Th) decay rate of 5 (15) kg1^{-1} d1^{-1} at 95% CL. We also searched for pairs of spatially correlated electron tracks separated in time by up to tens of days, as expected from 32^{32}Si-32^{32}P or 210^{210}Pb-210^{210}Bi sequences of β\beta decays. The decay rate of 32^{32}Si was found to be 8065+11080^{+110}_{-65} kg1^{-1} d1^{-1} (95% CI). An upper limit of \sim35 kg1^{-1} d1^{-1} (95% CL) on the 210^{210}Pb decay rate was obtained independently by α\alpha spectroscopy and the β\beta decay sequence search. These levels of radioactive contamination are sufficiently low for the successful operation of CCDs in the forthcoming 100 g DAMIC detector.Comment: 18 pages, 20 figure

    Search for low-mass WIMPs in a 0.6 kg day exposure of the DAMIC experiment at SNOLAB

    Get PDF
    We present results of a dark matter search performed with a 0.6 kg day exposure of the DAMIC experiment at the SNOLAB underground laboratory. We measure the energy spectrum of ionization events in the bulk silicon of charge-coupled devices down to a signal of 60 eV electron equivalent. The data are consistent with radiogenic backgrounds, and constraints on the spin-independent WIMP-nucleon elastic-scattering cross section are accordingly placed. A region of parameter space relevant to the potential signal from the CDMS-II Si experiment is excluded using the same target for the first time. This result obtained with a limited exposure demonstrates the potential to explore the low-mass WIMP region (<10 GeV/c2c^{2}) of the upcoming DAMIC100, a 100 g detector currently being installed in SNOLAB.Comment: 11 pages, 11 figure

    Criação de abelhas (apicultura).

    Get PDF
    Elaboradas em linguagem simples e objetiva, as publicações abordam temas relacionados à agropecuária e mostram como otimizar a atividade rural. A criação de animais, técnicas de plantio, práticas de controle de pragas e doenças, adubação alternativa e fabricação de conservas de frutas são alguns dos assuntos tratados.bitstream/item/11943/2/00081610.pdfProjeto Minibibliotecas

    Reactivity, performance, color and tenderness of meat from Zebu cattle finished in feedlot.

    Get PDF
    The objective of this study was to study the animal reactivity and correlate it with performance and meat quality of cattle finished in feedlots. A total of 20 animals of the Tabapuã breed and 20 animals of the Nellore breed were confined for 112 days: 28 days of adaptation and 84 days of data collection. Performance was determined by the average daily weight gain (ADG) and average dry matter intake (DMI) estimated through the use of indicators. On the 1st, 42nd and 84th days of the experiment, two methods were used to measure the animal reactivity: animal reactivity in mobile cage and visual reactivity during handling. The characteristics of meat quality were evaluated by the color, shear force and pH24 after slaughter (pH24). Through the study of correlation, the degree and direction of linear association on animal reactivity, performance and meat quality were established. Regression equations were generated for the parameters evaluated according to the values of animal reactivity. Correlations between mobile cage and visual reactivity were 0.77, 0.56 and 0.45 in the 1st, 2nd and 3rd evaluations, respectively. There was no correlation between animal reactivity and DMI. The correlations between ADG, pH24, and color with animal reactivity were -0.31, 0.40, 0.47 and -0.34, and -0.33 for mobile cage, 0.74, 0.71 and -0.51, for visual reactivity, respectively. The parameters of meat quality varied according to the reactivity. Undesirable values of pH24, animal reactivity and color were found when mobile cage reactivity was higher than 780, 590 and 540, respectively. In general, animals that show greater reactivity tend to have lower daily weight gain and lower meat quality. The reactivity can be used in animal breeding programs, in order to improve performance and meat quality of Zebu cattle finished in feedlot

    Diagnóstico socioeconômico-cultural e ambiental dos municípios do Projeto Boa Esperança.

    Get PDF
    A Embrapa Meio-Norte, por iniciativa da Chesf, com a qual estabeleceu uma parceria, vem desenvolvendo o Projeto Boa Esperança, visando resultar na melhoria dos níveis de produtividade e renda da atividade agropecuária, de forma participativa, além da mitigação da degradação ambiental. A importância desse projeto baseia-se na interação entre pesquisadores, extensionistas, agricultores familiares e pescadores organizados das comunidades, objetos de intervenção por intermédio do processo de difusão e transferência de alternativas tecnológicas. O projeto é composto de vários planos de ação, dos quais um pretende avaliar os aspectos sociotécnico-culturaleconômicos dos membros das comunidades, objeto das ações propostas no projeto, bem como levantar e organizar um sistema de informação de mercado da produção agrícola familiar em apoio ao projeto na geração de renda. Para a realização dos objetivos propostos, o projeto prevê que sejam realizados três diagnósticos participativos, no início, no meio e no final da sua execução, nas diversas comunidades da área de sua abrangência, onde se pretende implementar as atividades, com aplicação de questionário sociotécnico-cultural-econômico para identificação dos tipos de sistemas praticados, evolução da adoção das tecnologias e resultados finais obtidos pelos agricultores familiares e pescadores. Este documento traz o resultado do trabalho de prospecção realizado nas comunidades do entorno da Barragem de Boa Esperança, o qual contém dados sobre o agricultor/pescador, sua família e suas atividades, considerando o momento inicial de implementação do projeto.bitstream/item/83619/1/Doc-202-Diagnostico-completo.pd
    corecore