66 resultados para Jeans
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Dynamical models of stellar systems represent a powerful tool to study their internal structure and dynamics, to interpret the observed morphological and kinematical fields, and also to support numerical simulations of their evolution. We present a method especially designed to build axisymmetric Jeans models of galaxies, assumed as stationary and collisionless stellar systems. The aim is the development of a rigorous and flexible modelling procedure of multicomponent galaxies, composed of different stellar and dark matter distributions, and a central supermassive black hole. The stellar components, in particular, are intended to represent different galaxy structures, such as discs, bulges, halos, and can then have different structural (density profile, flattening, mass, scale-length), dynamical (rotation, velocity dispersion anisotropy), and population (age, metallicity, initial mass function, mass-to-light ratio) properties. The theoretical framework supporting the modelling procedure is presented, with the introduction of a suitable nomenclature, and its numerical implementation is discussed, with particular reference to the numerical code JASMINE2, developed for this purpose. We propose an approach for efficiently scaling the contributions in mass, luminosity, and rotational support, of the different matter components, allowing for fast and flexible explorations of the model parameter space. We also offer different methods of the computation of the gravitational potentials associated of the density components, especially convenient for their easier numerical tractability. A few galaxy models are studied, showing internal, and projected, structural and dynamical properties of multicomponent galaxies, with a focus on axisymmetric early-type galaxies with complex kinematical morphologies. The application of galaxy models to the study of initial conditions for hydro-dynamical and $N$-body simulations of galaxy evolution is also addressed, allowing in particular to investigate the large number of interesting combinations of the parameters which determine the structure and dynamics of complex multicomponent stellar systems.
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A recent integral-field spectroscopic (IFS) survey, the MASSIVE survey (Ma et al. 2014), observed the 116 most massive (MK < −25.3 mag, stellar mass M∗ > 10^11.6 M⊙) early-type galaxies (ETGs) within 108 Mpc, out to radii as large as 40 kpc, that correspond to ∼ 2 − 3 effective radii (Re). One of the major findings of the MASSIVE survey is that the galaxy sample is split nearly equally among three groups showing three different velocity dispersion profiles σ(R) outer of a radius ∼ 5 kpc (falling, flat and rising with radius). The purpose of this thesis is to model the kinematic profiles of six ETGs included in the MASSIVE survey and representative of the three observed σ(R) shapes, with the aim of investigating their dynamical structure. Models for the chosen galaxies are built using the numerical code JASMINE (Posacki, Pellegrini, and Ciotti 2013). The code produces models of axisymmetric galaxies, based on the solution of the Jeans equations for a multicomponent gravitational potential (supermassive black hole, stars and dark matter halo). With the aim of having a good agreement between the kinematics obtained from the Jeans equations, and the observed σ and rotation velocity V of MASSIVE (Veale et al. 2016, 2018), I derived constraints on the dark matter distribution and orbital anisotropy. This work suggests a trend of the dark matter amount and distribution with the shape of the velocity dispersion profiles in the outer regions: the models of galaxies with flat or rising velocity dispersion profiles show higher dark matter fractions fDM both within 1 Re and 5 Re. Orbital anisotropy alone cannot account for the different observed trends of σ(R) and has a minor effect compared to variations of the mass profile. Galaxies with similar stellar mass M∗ that show different velocity dispersion profiles (from falling to rising) are successfully modelled with a variation of the halo mass Mh.
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A Work Project, presented as part of the requirements for the Award of a Masters Degree in Management from the NOVA – School of Business and Economics.
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In order to shed light on the main physical processes controlling fragmentation of massive dense cores, we present a uniform study of the density structure of 19 massive dense cores, selected to be at similar evolutionary stages, for which their relative fragmentation level was assessed in a previous work. We inferred the density structure of the 19 cores through a simultaneous fit of the radial intensity profiles at 450 and 850 μm (or 1.2 mm in two cases) and the spectral energy distribution, assuming spherical symmetry and that the density and temperature of the cores decrease with radius following power-laws. Even though the estimated fragmentation level is strictly speaking a lower limit, its relative value is significant and several trends could be explored with our data. We find a weak (inverse) trend of fragmentation level and density power-law index, with steeper density profiles tending to show lower fragmentation, and vice versa. In addition, we find a trend of fragmentation increasing with density within a given radius, which arises from a combination of flat density profile and high central density and is consistent with Jeans fragmentation. We considered the effects of rotational-to-gravitational energy ratio, non-thermal velocity dispersion, and turbulence mode on the density structure of the cores, and found that compressive turbulence seems to yield higher central densities. Finally, a possible explanation for the origin of cores with concentrated density profiles, which are the cores showing no fragmentation, could be related with a strong magnetic field, consistent with the outcome of radiation magnetohydrodynamic simulations.
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The indigo blue dye is widely used in the textile industry. When discarded, besides polluting the environment, it affects the appearance and transparency of aquatic bodies, causing damage to flora and fauna. The removal of this dye from industrial effluents is difficult due to its resistance towards degradation. This work proposes the recovery of indigo blue by electroflocculation, as a subsidy for the treatment of effluents from the jeans industry.
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OBJETIVO: Descrever as práticas e cuidados com a área genital de mulheres universitárias. MÉTODOS: Estudo analítico descritivo, que analisou os hábitos e costumes de 364 estudantes de uma universidade pública do Estado de São Paulo quanto ao uso de roupas íntimas, piercings corporais, tatuagens, depilação e práticas sexuais. Um questionário com 42 perguntas avaliou as práticas habituais mais comuns das universitárias. Todas as perguntas foram autorrespondidas e os questionários, sem qualquer identificação, foram colocados em urnas lacradas para garantir o sigilo das informações. As respostas foram tabuladas em planilha Microsoft® Excel 2007 para obtenção de análise univariável. RESULTADOS: A média de idade das universitárias estudadas foi de 21 anos (DP±2,7), sendo 84% brancas. Participaram do estudo voluntárias das áreas de biológicas (50%), exatas (29%) e humanas (21%). Observou-se que 61,8% das entrevistadas usam calcinhas de algodão, porém, ao mesmo tempo, 75,4% usam calças jeans apertadas, e que somente 18,4% deixam de usar calcinha para dormir. Apenas uma participante relatou ter piercing genital e nenhuma tinha tatuagem. A maioria das universitárias faz depilação genital, sendo que aproximadamente um terço delas o faz de forma completa. Após depilar, dois terços usam produtos como anti-inflamatórios e/ou hidratantes na região. Apenas 62% usam camisinha masculina e 17,6% lubrificante na relação sexual. Metade pratica sexo oral receptor; 17,9% sexo anal e 26,6% delas relatam ter dor no ato sexual. Corrimento vaginal foi relatado após a relação sexual em 25,6% dos casos. CONCLUSÃO:Mulheres jovens de universidade pública brasileira têm muitos hábitos inadequados de cuidados relacionados à sua área genital. Não costumam usar piercings ou tatuagens genitais, mas relatam ter dor no ato sexual e corrimento vaginal após o sexo em um grande número de casos.
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Les naines brunes sont, en termes de masse, les objets astrophysiques intermédiaires entre les planètes géantes gazeuses et les étoiles de faible masse. Elles se forment de la même manière que les étoiles, par contraction gravitationnelle d’un fragment de nuage de gaz moléculaire ayant atteint la limite de Jeans, mais se différencient par leur incapa- cité à produire les réactions de fusion de l’hydrogène dans leur cœur. Les naines brunes sont par conséquent des objets qui se refroidissent graduellement, et dont les propriétés spectrales évoluent au cours du temps. Ce mémoire présente la recherche de nouvelles candidates de type spectral T tardif et Y, dans le but de compléter le relevé des naines brunes du voisinage solaire. Cette recherche est motivée par deux objectifs principaux. Premièrement, un échantillon com- plet des objets de faible masse est nécessaire pour contraindre correctement la limite aux faibles masses de la fonction de masse initiale des nuages interstellaires, problème clé en astrophysique actuellement. Deuxièmement, les naines brunes de types spectraux tardifs sont les objets stellaires dont les propriétés atmosphériques sont les plus semblables à celles des planètes géantes gazeuses. Par conséquent, la recherche de nouvelles naines brunes permet indirectement d’améliorer nos connaissances des exoplanètes, sans être contraints par la proximité d’étoiles brillantes. À partir du WISE All-Sky Source Catalog, nous avons établi un échantillon de 55 candidates naines brunes répondant aux critères photométriques attendus. Parmi ces can- didates, 17 ont fait l’objet d’un suivi photométrique en bande J à l’Observatoire du Mont-Mégantic, et 9 ont pu être détectées. De ces 9 détections, 4 objets présentent des mouvements propres cohérents avec ceux de naines brunes.
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Le présent travail se penche sur le concept de la conscience de l’environnement d’affaires. Ce concept fait référence à l’importance de la prise en compte par l’employé non-cadre d’un ensemble varié d’éléments d’information composant l’environnement d’affaires. La prise en considération de ces éléments d’information par l’employé aiderait ce dernier non seulement à prendre de meilleures décisions d’affaires, mais aussi à résoudre des problèmes dans un milieu de travail prônant la gestion participative. Seulement deux mémoires et un article scientifique se sont penchés sur la conscience de l’environnement d’affaires. Le mémoire d’Ève St-Onge (2007) a justifié l’existence du concept et a établi une première liste d’indicateurs reflétant les éléments d’information de l’environnement d’affaires. Pour sa part le mémoire de Véronique Gauvreau-Jean (2008) s’est plutôt attardé à la validation initiale d’une échelle de mesure de la conscience de l’environnement d’affaires. À ces deux mémoires s’ajoute l’article scientifique de Haines, Rousseau, Brotheridge et St-Onge (2012) lequel a permis de définir un ensemble d’indicateurs et de dimensions de la conscience de l’environnement d’affaires. Le présent mémoire a pour objectif de vérifier le caractère adéquat du contenu de l’échelle de Véronique Gauvreau-Jean (2008), ce type de vérification «consiste essentiellement à examiner le contenu du test pour s’assurer de sa représentativité en tant qu’échantillon du domaine de comportements à évaluer» (Anastasi, 1982, p.132). Considérant la complexité de la conscience de l’environnement d’affaires, cette vérification s’impose pour mettre au point une échelle de mesure qui peut être généralement applicable dans des milieux de travail ayant recours à une gestion participative. Pour vérifier le caractère adéquat du contenu de l’échelle de mesure de Véronique Gauvreau-Jean (2008), il y a eu l’animation de deux panels de discussion avec une entreprise œuvrant dans le placement de personnel ainsi qu’une autre dans la distribution de produits de papier. Avec les propos des participants des panels, une analyse des données a été effectué pour produire une échelle de mesure reformulée. Cette dernière a ensuite eu un avis favorable par deux professeurs, de différentes facultés d’administration québécoises, concernant la facilité de compréhension et sa capacité de refléter les éléments de l’environnement d’affaires. Il y a finalement eu la comparaison du contenu de l’échelle reformulée et du contenu de l’échelle de Gauvreau-Jean (2008) pour déterminer le caractère adéquat de l’échelle existante.
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This thesis deals with some aspects of the Physics of the early universe, like phase transitions, bubble nucleations and premodial density perturbations which lead to the formation structures in the universe. Quantum aspects of the gravitational interaction play an essential role in retical high-energy physics. The questions of the quantum gravity are naturally connected with early universe and Grand Unification Theories. In spite of numerous efforts, the various problems of quantum gravity remain still unsolved. In this condition, the consideration of different quantum gravity models is an inevitable stage to study the quantum aspects of gravitational interaction. The important role of gravitationally coupled scalar field in the physics of the early universe is discussed in this thesis. The study shows that the scalar-gravitational coupling and the scalar curvature did play a crucial role in determining the nature of phase transitions that took place in the early universe. The key idea in studying the formation structure in the universe is that of gravitational instability.
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This article studies some strategic issues on the implementation of structural reforms to public utilities in Colombia, establish on tha law 142 of 1994. The reform was held on a context of political debate where the palance favores a technocratic definition of the law. This jeans that local governments have been excluded from strategic decisions and that the model is characterized by its rigidity.
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As empresas do setor de vestuário estão passando por um novo paradigma influenciado por diversos fatores tais como: acirramento da competitividade resultado da internacionalização das empresas; abertura econômica; novos conceitos gerenciais e de gestão; investimentos em marca; consumidores cada vez mais exigentes e informados e principalmente a questão da moda que, influencia pela necessidade de investimento constante em inovação. Esse dinamismo observado no setor de vestuário induz os agentes participantes desse mercado a desenvolver estratégias competitivas que os diferenciem dos concorrentes e gerem um posicionamento na mente dos consumidores através de ações inovadoras. Neste sentido, este trabalho se concentra em observar como as empresas estão trabalhando no processo de geração e implementação das estratégias genéricas sob a luz das teorias sobre o assunto. O estudo visa ainda, identificar se as organizações estão alinhadas com as principais tendências competitivas e, para tanto, utiliza-se do estudo realizado pela equipe do Núcleo de Gestão da Inovação Tecnológica da Universidade Federal do Rio Grande do Sul (NITEC/UFRGS, 2002) que identificou quatro grandes tendências competitivas, cujas combinações acabam por definir as estratégias operacionais do negócio neste setor. O trabalho utiliza-se do método do estudo de caso e restringe a amostra a empresas gaúchas, produtoras de calças em jeans, que tenham mais de 50% de sua produção no estado do Rio Grande do Sul.
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In recent years, clusters have become a central part in discussions about local and regional economic development, as well as in the elaboration of public policies for generating jobs and income. Concurrent with the discussions about clusters, the subject globalization has also received growing attention from the media in the academic and government fields. Different aspects are considered in the discussions regarding globalization and one of the subjects is the insertion of local economies into international commerce. One of these ways of insertion is by global value chains. This term began to be used at the end of 90s, and refers to the productive value chains dispersed throughout the world, but with integrated production and commercialization. The aim of this thesis is to understand how the exportation process influences the development of fashion clusters, this being done by the insertion of these clusters into the global value chains. Each year, the Brazilian fashion sector seeks to broaden their participation in the global economy by means of insertion into the global value chains. This insertion, however, has caused impacts in specialized clusters of garment manufacturers, such as beach fashion, jeans and women¿s clothing. As a way of identifying these impacts, three cluster manufacturers were studied in the state of Rio de Janeiro, namely Cabo Frio, São Gonçalo and Niterói. The impacts of internationalization on the companies integrated into these three clusters were explored by means of a six-month field study, including semistructured interviews. This internationalization occurs either by direct exportation or by means of inserting these companies into the global value chains. The results of the study points out the opportunities and threats to these companies, as well as shows the importance of more adequate public policies for the development of Brazilian fashion clusters. Among these threats, the possibility of inserting these cluster companies into the global value chains in a captive manner (Gereffi, Humphrey, Sturgeon, 2005) was singled out, placing them ¿under control¿ of the exporting companies. As for opportunities, the participation of government support agencies and improvements in fashion show good alternatives for inserting these companies into the global value chains, making possible autonomous and competitive performance.
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The use of flexible materials for the development of planar circuits is one of the most desired and studied characteristics, lately, by researchers. This happens because the flexibility of the substrate can provide previously impracticable applications, due to the rigidity of the substrates normally used that makes it difficult to fit into the circuits in irregular surfaces. The constant interest in recent years for more lighter devices, increasingly more compacts, flexible and with low cost, led to a new line of research of great interest from both academic and technological views, that is the study and development of textile substrates that can be applied in the development of planar circuits, for applications in the areas of security, biomedical and telecommunications. This paper proposes the development of planar circuits, such as antennas , frequency selective surfaces (FSS) and planar filters, using textile (cotton ticking, jeans and brim santista) as the dielectric substrate and the Pure Copper Polyester Taffeta Fabric, a textile of pure copper, highly conductive, lightweight and flexible, commercially sold as a conductive material. The electrical characteristics of textiles (electric permittivity and loss tangent) were characterized using the transmission line method (rectangular waveguide) and compared with those found in the literature. The structures were analyzed using commercial software Ansoft Designer and Ansoft HFSS, both from the company Ansys and for comparison we used the Iterative Method of Waves (WCIP). For the purpose of validation were built and measured several prototypes of antennas, planar filters and FSS, being possible to confirm an excellent agreement between simulated and measured results
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The time evolution of the matter produced in high energy heavy-ion collisions seems to be well described by relativistic viscous hydrodynamics. In addition to the hydrodynamic degrees of freedom related to energy-momentum conservation, degrees of freedom associated with order parameters of broken continuous symmetries must be considered because they are all coupled to each other. of particular interest is the coupling of degrees of freedom associated with the chiral symmetry of QCD. Quantum and thermal fluctuations of the chiral fields act as noise sources in the classical equations of motion, turning them into stochastic differential equations in the form of Ginzburg-Landau-Langevin (GLL) equations. Analytic solutions of GLL equations are attainable only in very special circumstances and extensive numerical simulations are necessary, usually by discretizing the equations on a spatial lattice. However, a not much appreciated issue in the numerical simulations of GLL equations is that ultraviolet divergences in the form of lattice-spacing dependence plague the solutions. The divergences are related to the well-known Rayleigh-Jeans catastrophe in classical field theory. In the present communication we present a systematic lattice renormalization method to control the catastrophe. We discuss the implementation of the method for a GLL equation derived in the context of a model for the QCD chiral phase transition and consider the nonequilibrium evolution of the chiral condensate during the hydrodynamic flow of the quark-gluon plasma.