11,758 research outputs found

    Random Primordial Magnetic Fields and the Gas Content of Dark Matter Halos

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    We recently predicted the existence of random primordial magnetic fields (RPMF) in the form of randomly oriented cells with dipole-like structure with a cell size L0L_0 and an average magnetic field B0B_0. Here we investigate models for primordial magnetic field with a similar web-like structure, and other geometries, differing perhaps in L0L_0 and B0B_0. The effect of RPMF on the formation of the first galaxies is investigated. The filtering mass, MFM_F, is the halo mass below which baryon accretion is severely depressed. We show that these RPMF could influence the formation of galaxies by altering the filtering mass and the baryon gas fraction of a halo, fgf_g. The effect is particularly strong in small galaxies. We find, for example, for a comoving B_0=0.1\muG, and a reionization epoch that starts at zs=11z_s=11 and ends at ze=8z_e=8, for L0=100pcL_0=100\,\text{pc} at z=12z=12, the fgf_g becomes severely depressed for M<10^7\msun, whereas for B0=0B_0=0 the fgf_g becomes severely depressed only for much smaller masses, M<10^5\msun. We suggest that the observation of MFM_F and fgf_g at high redshifts can give information on the intensity and structure of primordial magnetic fields.Comment: 7 pages, 10 figures, accepted for publication in MNRAS (several improvements after suggestions of the referee

    Lumbar Spinal Stenosis, Clinical Presentation, Diagnosis, and Treatment

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    Lumbar spinal stenosis (LSS), a disease that mainly affects people over 50 years old, may have a dramatic presentation with pain, difficulty in walking, changes in urinary functions in addition to root symptoms, such as numbness, burning, and feeling of heaviness in the legs. The treatment is very varied with several non-surgical and surgical possibilities. With an aging population, this disease becomes increasingly preoccupant for their uncertain evolution and without a well-defined correlation with imaging tests, treatment, and outcome may be troublesome. Moreover, LSS frequently affects patients who have associated comorbidity that can hinder the treatment

    Playing an educational game featuring procedural content generation: which attributes impact players’ curiosity?

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    Understanding which and how attributes impact player experience can contribute to designing more tailored tools, providing concerns on how to improve these. However, there is a gap in the understanding of what impacts learners’ experience when interacting with Educational Games (EG) featuring Procedural Content generation (PCG) as these have been scantly used together. This article presents an empirical study on which attributes impact both math’s and game’s curiosity of players when interacting with an EG that uses PCG. The results show the attributes that led to higher or lower curiosity, as well aswhich of them are associated with it. Hence, advancing the understanding of what drives players’ curiosity, contributing to the design of EG that feature PCG

    Desempenho de aerogeradores de pequeno porte: simulação do fornecimento de energia elétrica a cargas conectadas à rede pública ou isoladas

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    The successful in the implementation of wind turbines depends on several factors, including: the wind resource at the installation site, the equipment used, project acquisition and operational costs. In this paper, the production of electricity from two small wind turbines was compared through simulation using the computer software HOMER - a national model of 6kW and an imported one of 5kW. The wind resources in three different cities were considered: Campinas (SP/BR), Cubatão (São Paulo/BR) and Roscoe (Texas/ USA). A wind power system connected to the grid and a wind isolated system - batteries were evaluated. The results showed that the energy cost (/kWh)isstronglydependentonthewindmillcharacteristicsandlocalwindresource.Regardingtheisolatedwindsystembatteries,thefullsupplyguaranteetothesimulatedelectricalloadisonlyachievedwithabatterybankwithmanyunitsandhighnumberofwindturbines,duetotheintermittencyofwindpower.Osucessonaaplicac\ca~odeaerogeradoresdependedevaˊriosfatores,dentreosquais:orecursoeoˊliconolocaldeinstalac\ca~o,osequipamentosutilizados,oscustosdeaquisic\ca~oeoperacionaisdoprojeto.Nestetrabalho,comparouseaproduc\ca~odeenergiaeleˊtricadedoisaerogeradoresdepequenoporte,sendoummodelonacionalde6kWeumimportadode5kW,pormeiodesimulac\ca~o,utilizandooprogramacomputacionalHOMER.Orecursoeoˊlicodetre^scidadesdiferentesfoiconsiderado:Campinas(SP/BR),Cubata~o(SP/BR)eRoscoe(TX/EUA).Umsistemaeoˊlicoconectadoaˋredeeleˊtricaeumsistemaisoladoeoˊlicobateriasforamavaliados.Osresultadosmostraramqueocustodaenergia(/kWh) is strongly dependent on the windmill characteristics and local wind resource. Regarding the isolated wind system batteries, the full supply guarantee to the simulated electrical load is only achieved with a battery bank with many units and high number of wind turbines, due to the intermittency of wind power.O sucesso na aplicação de aerogeradores depende de vários fatores, dentre os quais: o recurso eólico no local de instalação, os equipamentos utilizados, os custos de aquisição e operacionais do projeto. Neste trabalho, comparou-se a produção de energia elétrica de dois aerogeradores de pequeno porte, sendo um modelo nacional de 6kW e um importado de 5kW, por meio de simulação, utilizando o programa computacional HOMER. O recurso eólico de três cidades diferentes foi considerado: Campinas (SP/BR), Cubatão (SP/BR) e Roscoe (TX/EUA). Um sistema eólico conectado à rede elétrica e um sistema isolado eólico baterias foram avaliados. Os resultados mostraram que o custo da energia (/kWh) é fortemente dependente das características do aerogerador e do recurso eólico local. Em relação ao sistema isolado eólico - baterias, a garantia de suprimento integral à carga elétrica simulada só é alcançada com um banco de baterias com muitas unidades e alto número de aerogeradores, devido à intermitência da fonte eólica.36228129

    A glimpse on biological activities of tellurium compounds

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    Tellurium is a rare element which has been regarded as a toxic, non-essential trace element and its biological role is not clearly established to date. Besides of that, the biological effects of elemental tellurium and some of its inorganic and organic derivatives have been studied, leading to a set of interesting and promising applications. As an example, it can be highlighted the uses of alkali-metal tellurites and tellurates in microbiology, the antioxidant effects of organotellurides and diorganoditellurides and the immunomodulatory effects of the non-toxic inorganic tellurane, named AS-101, and the plethora of its uses. Inasmuch, the nascent applications of organic telluranes (organotelluranes) as protease inhibitors and its applications in disease models are the most recent contribution to the scenario of the biological effects and applications of tellurium and its compounds discussed in this manuscript.O telúrio é um elemento não-essencial raro que vem sendo considerado tóxico, e o seu papel biológico é ainda pouco esclarecido. Apesar disso, os efeitos biológicos do telúrio elementar e de alguns derivados inorgânicos e orgânicos que têm sido estudados revelam um conjunto de aplicações diversificadas interessantes e promissoras. Como exemplo, pode-se destacar os usos de teluritos e teluratos de metais alcalinos em microbiologia, o efeito antioxidante de teluretos e diteluretos orgânicos, os efeitos imunomodulatórios e a diversidade de usos correlacionados a este efeito de uma telurana inorgânica denominada AS-101. Ademais, as aplicações de teluranas orgânicas (organoteluranas) como inibidoras de proteases e as aplicações em modelos de doenças compõem a mais recente contribuição ao cenário dos efeitos e aplicações biológicas do telúrio e seus compostos discutidas neste manuscrito.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)UNIFESP Departamento de Ciências Exatas e da TerraUNIFESP Departamento de BiofísicaUNIFESP, Depto. de Ciências Exatas e da TerraUNIFESP, Depto. de BiofísicaSciEL

    A physical approach to modelling large-scale galactic magnetic fields

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    A convenient representation of the structure of the large-scale galactic magnetic field is required for the interpretation of polarization data in the sub-mm and radio ranges, in both the Milky Way and external galaxies. We develop a simple and flexible approach to construct parametrised models of the large-scale magnetic field of the Milky Way and other disc galaxies, based on physically justifiable models of magnetic field structure. The resulting models are designed to be optimised against available observational data. Representations for the large-scale magnetic fields in the flared disc and spherical halo of a disc galaxy were obtained in the form of series expansions whose coefficients can be calculated from observable or theoretically known galactic properties. The functional basis for the expansions is derived as eigenfunctions of the mean-field dynamo equation or of the vectorial magnetic diffusion equation. The solutions presented are axially symmetric but the approach can be extended straightforwardly to non-axisymmetric cases. The magnetic fields are solenoidal by construction, can be helical, and are parametrised in terms of observable properties of the host object, such as the rotation curve and the shape of the gaseous disc. The magnetic field in the disc can have a prescribed number of field reversals at any specified radii. Both the disc and halo magnetic fields can separately have either dipolar or quadrupolar symmetry. The model is implemented as a publicly available software package GalMag which allows, in particular, the computation of the synchrotron emission and Faraday rotation produced by the model's magnetic field. The model can be used in interpretations of observations of magnetic fields in the Milky Way and other spiral galaxies, in particular as a prior in Bayesian analyses. (Abridged.)Comment: 20 pages, 14 figures. Accepted for publication in A&
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